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Chiral 1D tin iodides EBASnI 3 were synthesized while incorporating enantiomerically pure and racemic ethylbenzylammonium (EBA) cations between the 1D shared inorganic corners. The dimensionality was reduced to 0D when replacing iodine with bromine. In all the cases, the presence of hydrogen bonds was observed between the organic part and the inorganic part, while transfer of chirality was evidenced for the EBASnI 3 enantiomerically pure compounds.

Herein, initially, we present a general overview of the global financial support for chemistry devoted to materials science, specifically intercalation layered compounds (ILCs). Subsequently, the strategies to synthesise these host structures and the corresponding guest-host hybrid assemblies are exemplified on the basis of some families of materials, including pillared clays (PILCs), porous clay heterostructures (PCHs), zirconium phosphate (ZrP), layered double hydroxides (LDHs), graphite intercalation compounds (GICs), graphene-based materials, and MXenes. Additionally, a non-exhaustive survey on their possible application in the field of energy through electrochemical storage, mostly as electrode materials but also as electrolyte additives, is presented, including lithium technologies based on lithium ion batteries (LIBs), and beyond LiBs with a focus on possible alternatives such XIBs (X = Na (NIB), K (KIB), Al (AIB), Zn (ZIB), and Cl (CIB)), reversible Mg batteries (RMBs), dual-ion batteries (DIBs), Zn-air and Zn-sulphur batteries and supercapacitors as well as their relevance in other fields related to (opto)electronics. This selective panorama should help readers better understand the reason why ILCs are expected to meet the challenge of tomorrow as electrode materials.

Intercalation compounds represent a unique class of materials that can be anisotropic (1D and 2D-based topology) or isotropic (3D) through their guest/host superlattice repetitive organisation. Intercalation refers to the reversible introduction of guest species with variable natures into a crystalline host lattice. Different host lattice structures have been used for the preparation of intercalation compounds, and many examples are produced by exploiting the flexibility and the ability of 2D-based hosts to accommodate different guest species, ranging from ions to complex molecules. This reaction is then carried out to allow systematic control and fine tuning of the final properties of the derived compounds, thus allowing them to be used for various applications. This review mainly focuses on the recent applications of intercalation layered compounds (ILCs) based on layered clays, zirconium phosphates, layered double hydroxides and graphene as heterogeneous catalysts, for environmental and health purposes, aiming at collecting and discussing how intercalation processes can be exploited for the selected applications.

Spin-state switching in iron(II) complexes composed of ligands featuring moderate ligand-field strength-for example, 2,6-bi(1 H -pyrazol-1-yl)pyridine (BPP)-is dependent on many factors. Herein, we show that spin-state switching in isomeric iron(II) complexes composed of BPP-based ligands-ethyl 2,6-bis(1 H -pyrazol-1-yl)isonicotinate (BPP-COOEt, L1) and (2,6-di(1 H -pyrazol-1-yl)pyridin-4-yl)methylacetate (BPP-CH 2 OCOMe, L2)-is dependent on the nature of the substituent at the BPP skeleton. Bi-stable spin-state switching-with a thermal hysteresis width (Δ T 1/2 ) of 44 K and switching temperature ( T 1/2 ) = 298 K in the first cycle-is observed for complex 1·CH 3 CN composed of L1 and BF 4 - counter anions. Conversely, the solvent-free isomeric counterpart of 1·CH 3 CN-complex 2a, composed of L2 and BF 4 - counter anions-was trapped in the high-spin (HS) state. For one of the polymorphs of complex 2b·CH 3 CN-2b·CH 3 CN-Y, Y denotes yellow colour of the crystals-composed of L2 and ClO 4 - counter anions, a gradual and non-hysteretic SCO is observed with T 1/2 = 234 K. Complexes 1·CH 3 CN and 2b·CH 3 CN-Y also underwent light-induced spin-state switching at 5 K due to the light-induced excited spin-state trapping (LIESST) effect. Structures of the low-spin (LS) and HS forms of complex 1·CH 3 CN revealed that spin-state switching goes hand-in-hand with pronounced distortion of the trans-N {pyridyl}-Fe-N{pyridyl} angle ( ϕ ), whereas such distortion is not observed for 2b·CH 3 CN-Y. This observation points that distortion is one of the factors making the spin-state switching of 1·CH 3 CN hysteretic in the solid state. The observation of bi-stable spin-state switching with T 1/2 centred at room temperature for 1·CH 3 CN indicates that technologically relevant spin-state switching profiles based on mononuclear iron(II) complexes can be obtained.

In order to prepare self-standing and flexible slow neutron reflectors made of graphite fluoride (GF) with high contents of (C 2 F) n structural phase, graphite foils of different thicknesses were used as starting materials for gas (F 2 )/solid fluorination. The maximal interlayer distance of GF was obtained with this phase thanks to the stacking sequence FCCF/FCCF; this is mandatory for the efficient reflection of slow neutrons. 71 and 77% of the (C 2 F) n phase were achieved for graphite foils with thicknesses of 1.0 and 0.1 mm, respectively. The interlayer distances were 8.6 Å as expected. The fluorination conditions (static mode, a long duration of 24 h, annealing in pure F 2 gas for 24 h, and temperatures in the 390-460 °C range) were adapted to large pieces of graphite foils (7 × 7 cm 2 ) in order to both avoid exfoliation and achieve a homogeneous dispersion of fluorine atoms. This process was also efficient for thinner (0.01 mm thick) graphitized graphene oxide foil. 56% of the (C 2 F) n phase and an interlayer of 8.6 Å were achieved for this foil when fluorination was performed at 430 °C. Whatever the nature and the thickness of the foil, their flexibilities are maintained.

The impact of isomerism of pyrimidine-based ligands and their rhodium(III) complexes with regard to their structures and properties was investigated. Two isomeric ligands, 4-(3,5-dimethyl-1 H -pyrazol-1-yl)-2,5-diphenylpyrimidine (HL2,5) and 4-(3,5-dimethyl-1 H -pyrazol-1-yl)-2,6-diphenylpyrimidine (HL2,6), were synthesized. The ligands differ by the degree of steric bulk: the molecular structure of HL2,5 is more distorted due to presence of pyrazolyl and phenyl groups in the neighbouring positions 4 and 5 of the pyrimidine ring. The complexation of HL2,5 and HL2,6 with RhCl 3 leads to the sp 2 C-H bond activation, resulting in the isolation of two complexes, [RhL2,5(Solv)Cl2]·nEtOH and [RhL2,6(Solv)Cl2]·nEtOH (Solv = H 2 O, EtOH), with the deprotonated forms of the pyrazolylpyrimidine molecules which coordinate the Rh 3+ ion as N^N^C-tridentate ligands. According to DFT modelling, the mechanism of the deprotonation involves (i) the C-H bond breaking in the 2-phenyl group followed by the coordination of the C atom to the Rh atom, (ii) the protonation of coordinated chlorido ligand, (iii) the ejection of the HCl molecule and (iv) the coordination of the H 2 O molecule. The ligand isomerism has an impact on emission properties and cytotoxicity of the complexes. Although the excited states of the complexes effectively deactivate through S 0 /T 1 and S 0 /S 1 crossings associated with the cleavage of the weak H 2 O ligands upon excitation, the [RhL2,5(Solv)Cl2]·nEtOH complex appeared to be emissive in the solid state, while [RhL2,6(Solv)Cl2]·nEtOH is non-emissive at all. The complexes show significant cytotoxic activity against cancerous HepG2 and Hep2 cell lines, with the [RhL2,6(Solv)Cl2]·nEtOH complex being more active than its isomer [RhL2,5(Solv)Cl2]·nEtOH. On the other hand, noticeable cytotoxicity of the latter against HepG2 is supplemented by its non-toxicity against non-cancerous MRC-5 cells.

In this study, the insertion of fluorine into LiFePO 4 was carried out under molecular fluorine F 2 at different temperatures. The reactivity strongly depends on the applied fluorination temperature, leading to very different products: core delithiation of the material is observed at low temperatures with the formation of a LiF shell around particles, while the material decomposes to gradually form a mixture of α-FeF 3 and α-Li 3 FeF 6 iron fluorides at higher temperatures. A second thermal treatment under N 2 leads to the formation of LiFePO 4 F in a new way that has not been reported before. Supported by X-ray diffraction, Raman, infrared, Mössbauer spectroscopies, 7 Li nuclear magnetic resonance and electrochemical characterization of the different materials, this report demonstrates various fluorination mechanisms for LiFePO 4 , from chemical delithiation to the stable pure fluorinated form LiFePO 4 F and illustrates an innovative method that can be extended to obtain the triphylite form of NaFePO 4 .

The advancement of lithium-ion batteries (LIBs) with high performance is crucial across various sectors, notably in space exploration. This advancement hinges on the development of innovative cathode materials. Our research is dedicated to pioneering a new category of cathodes using fluorinated multimetallic materials, with a specific focus on diverging from the traditional Ni, Co, and Mn-based NMC chemistries by substituting nickel and manganese with copper and iron which are more sustainable elements. Our goal is also to enhance the robustness of cathodes upon cycling by substituting oxygen with fluorine as the metal-ligand. To achieve this, an intimate composite blend of CuF 2 and FeF 3 , through the multi-metallic template fluorination (MMTF) methodology using a layered double hydroxide (LDH) as a precursor has been designed. Each of these components was carefully selected for its distinct attributes, including high redox potential, elevated energy density, substantial theoretical capacity, and improved cyclability. The composition denoted as (Cu 1.5 Co 0.5 ) 2+ (Fe 0.75 Al 0.25 ) 3+ has been selected for fluorination because it maximizes Fe 3+ and Cu 2+ amount in the screened LDHs. Subsequently, this particular LDH was fluorinated through solid-gas fluorination at different temperatures (200, 350, and 500 °C) using gaseous molecular fluorine (F 2 ). A comprehensive characterization of these materials using various techniques, including X-ray diffraction (XRD), 57 Fe Mössbauer spectrometry, scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), and inductively coupled plasma analyses (ICP-AES) was conducted, and the evolution of LDH upon fluorination has revealed an intermediate porous texture particularly sensitive to hydration. Two original crystallographic phases are else obtained by fluorination: one formed by the hydration of the amorphous intermediate compound: Cu 3 Fe 1.5 Al 0.5 F 12 (H 2 O) 12 an anti-perovskite structure and another stabilized through the combination of solid gas fluorination and LDH precursor yielding an original CoFeF 5 -type phase. Raman operando during cyclic voltammetry measurement applied on a sample fluorinated at 500 °C and used as a cathode in front of lithium metal was finally conducted to validate redox activity and mechanism.

Two different alkynyl-substituted C 3 -symmetric cyclotribenzylenes (CTB) were synthesized in racemic and enantiomerically pure forms, and six gold(I) phosphine complexes differing by the nature of the CTB and the phosphine were prepared and characterized, in particular by NMR spectroscopy, DOSY, electronic circular dichroism (ECD), and electrospray ionization mass spectrometry (ESI-MS). Their ECD patterns depended on the substitution of the starting CTBs and were shifted bathochromically by comparison with the latter. ESI-MS in the presence of HCO 2 H allowed us to detect the complexes as proton adducts. The intensities of the signals were stronger when the phosphine was more electron-rich. This technique was also used to investigate the exchange of phosphine betweeen pairs of CTB complexes. The scrambling reaction was demonstrated by the higher intensity of the signals of the complexes subjected to the exchange of a single phosphine ligand by comparison with the intensity of the signals of the starting complexes.

The chelator diacetyl-bis( N 4-methylthiosemicarbazone) (ATSM) and its complexes with Cu II and Zn II are becoming increasingly investigated for medical applications such as PET imaging for anti-tumour therapy and the treatment of amyotrophic lateral sclerosis. However, the solubility in water of both the ligand and the complexes presents certain limitations for in vitro studies. Moreover, the stability of the Cu II and Zn II complexes and their metal exchange reaction against the potential biological competitor human serum albumin (HSA) has not been studied in depth. In this work it was observed that the ATSM with an added carboxylic group into the structure increases its solubility in aqueous solutions without altering the coordination mode and the conjugated system of the ligand. The poorly water-soluble Cu II - and Zn II -ATSM complexes were prevented from precipitating due to the binding to HSA. Both HSA and ATSM show a similar thermodynamic affinity for Zn II . Finally, the Cu II -competition experiments with EDTA and the water-soluble ATSM ligands yielded an apparent log  K d at pH 7.4 of about -19. When ATSM was added to Cu II - and Zn II -loaded HSA, withdrawing of Zn II was kinetically favoured, but this metal is slowly substituted by the Cu II afterwards taken from HSA so that this protein could be considered as a source of Cu II for ATSM.

The conformational preference of a cavity-based biaryl phosphine, namely 5-(2-diphenylphosphinyl-phenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (L) has been investigated by density functional theory calculations. The analysis showed that the barrier to rotation about the C-C axle of the biaryl unit is only 10.7 kcal mol -1 , this rendering possible access to conformers of two types, those in which the P lone pair sits at the cavity entrance and points to the calixarene interior, others with a more open structure where the P atom is located outside the cavity. As revealed by a single crystal X-ray diffraction study, the biaryl phosphine appears virtually as an atropisomer in the solid state in which the phosphorus atom lies totally out of the cavity defined by the four phenoxy rings.

Metal ions play a very important role in nature and their homeostasis is crucial. A lot of metal-related chemical research activities are ongoing that concern metal-based drugs or tools, such as chelation therapy, metal- and metabolite sensors, metallo-drugs and prodrugs, PET and MRI imaging agents, etc . In most of these cases, the applied chelator/ligand (L) or metal-ligand complex (M-L) has at least to pass the blood plasma to reach the target. Hence it is exposed to several metal-binding proteins (mainly serum albumin and transferrin) and to all essential metal ions (zinc, copper, iron, etc .). This holds also for studies in cultured cells when fetal calf serum is used in the medium. There is a risk that the applied compound (L or M-L) in the serum is transformed into a different entity, due to trans-metallation and/or ligand exchange reactions. This depends on the thermodynamics and kinetics. For kinetically-labile complexes, the complex stability with all the ligands and all metal ions present in serum is decisive in evaluating the thermodynamic driving force towards a certain fate of the chelator or metal-ligand complex. To consider that, an integrative view is needed on the stability constants, by taking into account all the metal ions present and all the main proteins to which they are bound, as well as the non-occupied metal binding site in proteins. Only then, a realistic estimation of the complex stability, and hence its potential fate, can be done. This perspective aims to provide a simple approach to estimate the thermodynamic stability of labile metal-ligand complexes in a blood plasma/serum environment. It gives a guideline to obtain an estimation of the plasma and serum complex stability and metal selectivity starting from the chemical stability constants of metal-ligand complexes. Although of high importance, it does not focus on the more complex kinetic aspects of metal-transfer reactions. The perspective should help for a better design of such compounds, to perform test tube assays which are relevant to the conditions in the plasma/serum and to be aware of the importance of ternary complexes, kinetics and competition experiments.

Metal ions (Ag + , Cd 2+ , Eu 3+ , Sm 3+ ) and protons can, through coordination and protonation, modulate in three specific ways the structural information contained in the pyrazine-based heterocyclic strand L (obtained from 2,5-bis(methylhydrazino)pyrazine and 2 equivalents of 2-pyridinecarboxaldehyde), thus generating two linear rod-like conformations and a bent one. This conformational diversity is associated with a structural one that consists of two diprotonated forms (H 2 L(PF 6 ) 2 and H 2 L(CF 3 SO 3 ) 2 ), a polymeric architecture [AgL] n (CF 3 SO 3 ) n , two rack-like complexes ([Eu 2 H 2 L 3 (CF 3 SO 3 ) 6 ](PF 6 ) 2 and [Sm 2 H 2 L 3 (CF 3 SO 3 ) 6 ](PF 6 ) 2 ) and a grid-like structure ([Cd 4 L 4 ](CF 3 SO 3 ) 8 ).

The presence of a permethylated α-cyclodextrin (α-CD) cavity in a chelating P,N ligand promotes exclusive formation of 1 : 1 ligand/metal complexes. In MX 2 complexes, one of the two halido ligands is forced to reside inside the CD hollow while the second one is pointing outside. Unlike its cavity-free analogue, a Ni(II) complex of the CD ligand is a highly selective precatalyst for ethylene dimerisation (96% C 4 selectivity with up to 95% of 1-butene within the C 4 fraction).

The one-dimensional coordination polymers {[Cu II (hfac) 2 ] 3 ( m -BNN)} n · n CH 2 Cl 2 (1 ·CH 2 Cl 2 , P 1̄) and {[Cu II (hfac) 2 ] 3 ( m -BNN)} n (1', P 2/ n ), hfac = hexafluoroacetylacetonate and m -BNN = meta -phenylene bis(nitronyl-nitroxide), were obtained from CH 2 Cl 2 and CHCl 3 , respectively. 1 ·CH 2 Cl 2 is transformed to 1 at 335 K. Their magnetic susceptibilities differ in both magnitude and temperature dependence behavior. 1 and 1' undergo a ferroelastic-like phase transition at 110 K and an unidentified one at 37 K. There is a subtle long relaxation of this ferroelastic-like ordered state.

The fate of HKUST-1 (Cu 3 (BTC) 2 , BTC = 1,3,5-benzenetricarboxylate) in the green Deep Eutectic Solvent (DES) reline (choline chloride/urea 1 : 2) was investigated, highlighting that not only reline can be used to make this MOF but also to transform it into another crystalline material. The synthesis of HKUST-1(reline) showing good textural properties and a particular rose morphology was indeed successfully achieved in this solvent. However, upon optimizing the reaction conditions such as concentration and metal/ligand ratio, it was found that another structure Cu 2 (BTC)Cl also forms. It was unequivocally demonstrated that, upon heating in reline, HKUST-1 converts to the non-porous chloride-incorporating material. Hence, a novel feature of DES in MOF synthesis is uncovered: its role as a structure-directing agent, triggering the transformation between two different MOF structures.

Sometimes named half-porphyrins, bis-pyrrolic dipyrrin ligands endow their metal complexes with unique properties such as the potential to functionalize the heterocyclic backbone or the meso position and the ability to catalyze interesting chemical transformations. Thus, strategies towards the derivatization of or at the meso group and the use of dipyrrin metal complexes for the formation of a broad range of polypyrrolic derivatives such as 2,2'-bis-dipyrrins, nor-/hetero-corroles and porphynoids have been elaborated. Furthermore, the chelating ability of dipyrrins and the possibility of modifying their steric and electronic characteristics by functionalization can be exploited for the development of numerous complexes featuring appealing properties. Hence, C-H activation/amination, polymerization or oxidation reactions can be catalyzed by dipyrrin metal complexes and classical reagents such as Grignard species, Rh-based or Suzuki-Miyaura catalysts have been revisited by incorporation of dipyrrins in the coordination sphere of the metal cations. This contribution aims to review and illustrate all these aspects, highlighting the potential of these complexes for the design and synthesis of valuable organic compounds and metallo-organic architectures.

Photochemical reactions of (PPh4)[OsVI(N)(L)(CN)3] (NO2-OsN) with piperidine and pyrrolidine afforded two osmium(v) hydrazido compounds, (PPh4)[OsV(L)(CN)3(NNC5H10)] ([PPh4]1) and (PPh4)[OsV(L)(CN)3(NNC4H8)] ([PPh4]2), respectively. Their structures consist of isolated, mononuclear distorted octahedral osmium anions that are well-separated from each other by PPh4+. Their low spin S = 1/2 and L = 1 ground state was confirmed by magnetometry and DFT calculations. Interestingly, both compounds exhibit slow magnetic relaxation under a bias dc-field. These osmium(v) complexes are potentially useful building-blocks for the construction of molecule-based architectures with interesting magnetic properties. In contrast, the structurally related (PPh4)[OsIII(L)(CN)3(NH3)] ([PPh4]3), which also has a low-spin S = 1/2 ground state but with a different electronic configuration (5d5), does not exhibit slow magnetic relaxation, due to the absence of any orbital moment (L = 0). Furthermore, the structurally different osmium(v) hydrazido compound reported by Meyer, [OsV(tpy)(Cl)2(NNC5H10)](PF6) (4[PF6]), also does not exhibit slow magnetic relaxation due possibly to a change in magnetic anisotropy from axial for [PPh4]1 and [PPh4]2 to planar.

Bi-stable charge-neutral iron(ii) spin-crossover (SCO) complexes are a class of switchable molecular materials proposed for molecule-based switching and memory applications. In this study, we report on the SCO behavior of a series of iron(ii) complexes composed of rationally designed 2-(1H-pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine (ptp) ligands. The powder forms of [Fe 2+ (R-ptp - ) 2 ] 0 complexes tethered with less-bulky substituents-R = H (1), R = CH 2 OH (2), and R = COOCH 3 (3; previously reported)-at the 4-position of the pyridine ring of the ptp skeleton showed abrupt and hysteretic SCO at or above room temperature (RT), whereas complex 5 featuring a bulky pyrene substituent showed incomplete and gradual SCO behavior. The role of intermolecular interactions, lattice solvent, and electronic nature of the chemical substituents (R) in tuning the SCO of the complexes is elucidated.

Reversible turn-on fluorescent sensors of Cu(ii) are of high interest for biological studies. We re-investigate a reported sensor, showing that turn-on occurs via irreversible Cu(ii)-induced sensor oxidation only in the presence of acetonitrile. This prevents its application in biological studies and highlights the challenge of establishing a reversible Cu(ii) turn-on sensor.

A series of new Pd-PEPPSI complexes containing imidazolylidene ligands with a mixed 9-alkyl-9-fluorenyl/aryl N,N'-substitution pattern have been synthesised. Single crystal X-ray diffraction studies were carried out for four complexes, which revealed that the N-heterocyclic carbene ligands display a semi-open, unsymmetrical space occupancy about the metal. Despite their particular unsymmetrical shape, the new complexes were found to perform as well in Suzuki-Miyaura cross coupling (dioxane, 80 °C) as previously reported, highly active analogues bearing two sterically protecting 9-alkylfluorenyl substituents. They were further found to be considerably more active than the standard Pd-PEPPSI complexes [PdCl 2 IMes(pyridine)] and [PdCl 2 IPr(pyridine)]. Surprisingly, unlike the latter, the unsymmetrical complexes of this study were practically inactive in isopropanol at 80 °C. Under these conditions the complexes appear to decompose with formation of non-stabilised nanoparticles.

Analyses of the structural information of molecular fragments from the mass spectra of the solid-state products and their reaction solutions allow for the understanding of their formation and of their diverse properties. The reaction of CuCl 2 and (1-methyl-1H-benzo[d]imidazole-2-yl)methanol (HL) led only to crystals containing molecular dimers of [Cu 2 (L) 2 Cl 2 ] (Cu2). The Cu II -Cu II distance and Cu-OR-Cu angle in the structure are 3.044 Å and 104.8°, respectively. The magnetic susceptibility (3-400 K) is characterized by a very strong intradimer antiferromagnetic interaction of J = -465 and interdimer zj = -0.83 cm -1 . But mass spectrometry of a dissolved single crystal in different source energies identifies both its fragmentation and oligomerization to [Cu] and [Cu]. DFT calculations give the relative stabilization energies of the fragments observed in ESI-MS to provide a formation process.

With their N-amine and N'-imine substituents, the imidazolium chlorides [(ImH){C(Me)[double bond, length as m-dash]NDipp}(C 2 NMe 2 )]Cl (1) and [(ImH){C(Me)[double bond, length as m-dash]NDipp}(C 3 NMe 2 )]Cl (2) are suitable precursors to pincer-type tritopic N imine C NHC N amine ligands for various transition metals and allow an investigation of the influence of (i) the functionalities associated with the NHC donor and (ii) the length of the spacer connecting the amine group to the heterocycle. The mononuclear Cu(i) complexes [CuCl{Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 1 C NHC }] (3) and [CuCl{Im[C(Me)[double bond, length as m-dash]NDipp](C 3 NMe 2 )-κ 1 C NHC }] (4) were prepared by the reaction of 1 and 2 with mesitylcopper(i), respectively. The reactions of 1 and 2 with Ag 2 O, in the presence of molecular sieves, afforded the Ag(i) complexes [AgCl{Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 1 C NHC }] (5) and [AgCl{Im[C(Me)[double bond, length as m-dash]NDipp](C 3 NMe 2 )-κ 1 C NHC }] (6), respectively. A dinuclear Cu(i) complex containing a ladder-type skeleton formed by copper and iodine atoms, [Cu 4 (μ 2 -I) 2 (μ 3 -I) 2 {μ-κ 2 -C NHC ,N amine (Im){C(Me)[double bond, length as m-dash]NDipp}(C 3 NMe 2 )} 2 ] (7), was obtained by deprotonation of 2 using sodium trimethylsilylamide/CuI. A transmetallation reaction from 5 to [NiBr 2 (dme)] afforded an unexpected mixed-metal tetranuclear, centrosymmetric complex [NiCl{Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 1 C NHC }{μ 2 -κ 3 -N imine ,C NHC ,N amine Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )}AgBr 2 ] 2 (8), which contains two mononuclear Ni(ii) units, one with a κ 1 C NHC donor and the other with a κ 2 -N imine ,C NHC chelating and μ 2 -C NHC ,N amine bridging ligand. These two monocationic complexes are connected by the dianonic, disilver unit [Ag 2 Br 4 ] 2- . Furthermore, the mononuclear tritopic Ni(ii) pincer complexes [Ni(NCMe){Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 3 N imine ,C NHC ,N amine }][BF 4 ] 2 (9) and [Ni(NCMe){Im[C(Me)[double bond, length as m-dash]NDipp](C 3 NMe 2 )-κ 3 N imine ,C NHC ,N amine }][BF 4 ] 2 (10) were obtained when [Ni(NCMe) 6 ](BF 4 ) 2 was used as a precursor in transmetallation reaction with 9 and 10, respectively. Transmetallation from the silver complexes 5 and 6 was also applied to the synthesis of chromium complexes and whether [CrCl 2 (THF) 2 ] or [CrCl 3 (THF) 3 ] was used as a precursor, the same chromium(iii) complexes, mer-[CrCl 3 {Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 3 N imine ,C NHC ,N amine }] (11) and mer-[CrCl 3 {Im[C(Me)[double bond, length as m-dash]NDipp](C 3 NMe 2 )-κ 3 N imine ,C NHC ,N amine }] (12), respectively, were isolated. Moreover, silver transmetalation reactions from 5 and 6 were successfully applied to the Ir(i) precursor [Ir(μ-Cl)(cod)] 2 (cod = 1,5-cycloocadiene) and the Ir(i) complexes [IrCl(cod){Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 1 C NHC }] (13) and [IrCl(cod) {Im[C(Me)[double bond, length as m-dash]NDipp](C 3 NMe 2 )-κ 1 C NHC }] (14), respectively, containing a monodentate NHC ligand were isolated as yellow crystals in good yields. The cationic, N imine ,C NHC -chelated Ir(i) complexes [Ir(cod){Im[C(Me)[double bond, length as m-dash]NDipp](C 2 NMe 2 )-κ 2 N imine ,C NHC }]BF 4 (15) and [Ir(cod){Im[C(Me)[double bond, length as m-dash]NDipp](C 3 NMe 2 )-κ 2 N imine ,C NHC }]BF 4 (16) were obtained by halide abstraction from 13 and 14, respectively. The following 10 complexes 3, 6, 7, 8·2Et 2 O, 9-11, 12·2C 7 H 8 , 14 and 16·THF were characterized by X-ray diffraction analysis. In catalytic ethylene oligomerization, the Ni complex 10 showed a productivity of 14 600 gC 2 H 4 per (gNi h), giving 65% butenes and 30% hexenes. With the Cr complex 12, the productivity was up to 9200 gC 2 H 4 per (gCr h) and a very high selectivity for α-olefins was observed, from C 4 to C 8 .

The development of bifunctional non-noble metal electrocatalysts demonstrating high activity and stability for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for renewable and clean energy. In this work, we report hierarchically structured integrated Fe-MoS 2 /Ni 3 S 2 /NF (NF = nickel foam) materials prepared by a facile in situ solvothermal method, and among them, the Fe-doped MoS 2 was assembled into spine-like nanorods. The optimized electrocatalyst (denoted as Fe-MoS 2 /Ni 3 S 2 /NF-2) demonstrated excellent activity and durability for performing the HER and OER in an alkaline electrolyte (pH = 14) with low overpotentials of 130.6 mV and 256 mV (vs. RHE) at a current density of 10 mA cm -2 , as well as no significant loss in catalytic performance even after 2000 cyclic voltammetry (CV) cycles. An outstanding durability of 180 h could be achieved for OER. The overall water splitting made up of the two-electrode system with Fe-MoS 2 /Ni 3 S 2 /NF-2 as both the anode and the cathode required a voltage of only 1.61 V to drive a current density of 10 mA cm -2 along with an outstanding long-term stability of 20 h, displaying its great potential for application in water splitting. The effective construction of multi-component synergistic structures shows a good pathway for high-performance electrocatalysis and energy storage.

A molecular tweezer incorporating two acridinium moieties linked by a 1,3-dipyridylbenzene spacer was synthesized in three steps. The formation of its self-complementary dimer in water was demonstrated as a result of π-π stacking and hydrophobic interactions. Moreover, a 1 : 1 mixture of this bis-acridinium tweezer with one built on a 2,6-diphenylpyridyl spacer evidenced its narcissistic self-sorting behaviour in water.

Stable complexes [Ti(1a)(2)2] and [Ti(1b)(2)2], where 2 is the 6,6'-diphenyl-2,2'-biphenolato ligand and 1a and 1b ligands are 2,2'-bipyrimidine derivatives, are synthesized. The complex [Ti(1b)(2)2] containing a diimine ligand substituted with long alkyl chains (C16) exhibits a liquid crystal behaviour. This property and self-assembling in the crystalline state are explained by the particular molecular conformation of the complexes.

In this work we investigate how the crystal packing affects the spin crossover (SCO) of [FeII(2-pic)3]Cl2. Four alcohol solvatomorphs of this compound have been reported to present a transition from a singlet low spin (LS, S = 0) to a quintet high spin (HS, S = 5) state at different temperatures, whereas two other solvatomorphs remain in the HS state along the entire range of temperatures explored. Given that all these solvatomorphs are isostructural, this behavior hints at crystal packing effects playing an important role in the spin transition. With the aim of deciphering their origin, we performed periodic DFT+U+D2 computations on the crystal lattices of the six solvatomorphs to quantify the importance of all possible molecular and intermolecular contributions to their spin-state energetics. We demonstrate that the spin crossover of the alcohol solvatomorphs of [FeII(2-pic)3]Cl2 (1) is strongly influenced by the change of intermolecular interactions. We prove that isolated molecules of 1 would not undergo SCO, whereas intermolecular interactions are crucial to allow the spin transition in the solid state. The key interactions are those between (i) different SCO molecules (stabilizing the LS) and (ii) between SCO molecules and counterions (stabilizing the HS). Moreover, we show that these contributions are proportional to the crystal expansion associated with the phase change, in a way that larger volume expansions imply larger changes in these contributions, with the overall effect of stabilizing the LS state of the material. Finally, we discuss how our results challenge the common perspective that associates the cooperativity of a spin transition with the number- and strength- of intermolecular contacts in the crystal.

The present study first describes the reactivity of low valent Al(ii) and Ga(ii) complexes of the type (dpp-bian)M-M(dpp-bian) (1, M = Al; 2, Ga; dpp-bian2- = 1,2-bis-(2,6-iPr2-C6H3)-acenaphthenequinonediamido) with cyclic esters/carbonates such as ε-caprolactone (CL) and trimethylene carbonate (TMC). CL and TMC both readily coordinate to the Al(ii) species 1 to form the corresponding bis-adducts (dpp-bian)Al(L)-(L)Al(dpp-bian) (3, L = CL; 4, L = TMC), which were structurally characterized confirming that the Al(ii)-Al(ii) dimetallic backbone retains its integrity in the presence of such cyclic polar substrates. In contrast, the less Lewis acidic Ga(ii) analogue 2 shows no reaction in the presence of stoichiometric amounts of CL and TMC at room temperature. In combination with BnOH, the dinuclear Al(ii) species 1 revealed to be an extremely active Al(ii) initiator for the controlled ROP of CL at room temperature, outperforming all its Al(iii) congeners reported thus far. Detailed DFT studies on the ROP mechanism are consistent with a process occurring thanks to the metallic cooperativity between the two Al(ii) proximal (since directly bonded) metal centers in 1, which undoubtedly favors the ROP process through bimetallic activation and thus rationalizes the unusually high CL ROP activity at room temperature.

A coordination chemistry involving trans-TiO4N2 motifs is described, where the oxygen ligands are 2,2'-biphenolato derivatives (L1 or L2) and the nitrogen ligands are pyridine (Pyr), 2,3-dihydro-7-azaindole (DHA) or 2-(methylamino)pyridine (MePyr). Monomeric complexes and double-stranded helicates incorporating this set of ligands are characterized. The monomeric species are obtained from the precursor [Ti(L1)2(HOiPr)2] whereas the helical dinuclear architectures are synthesized following a multicomponent self-assembly approach starting from L2H4, Ti(OiPr)4 and two equivalents of the nitrogen ligand. It is proposed that the trans isomerism in TiO4N2 observed in these structures results from the destabilisation of the cis isomer by the trans influence of the Ti-N bonds. The crystal structures and infra-red analysis demonstrate hydrogen bonding interactions occurring between the NH group of DHA or MePyr and the oxygens belonging to the titanium coordination sphere. The strength of these interactions is estimated using the PACHA (Partial Atomic Charges Analysis) software.

The double aminolysis reaction of [Co{N(SiMe3)2}2] by the salt 1-(6-((dicyclohexylphosphaneyl)methyl)pyridin-2-yl)-3-(2,6-diisopropylphenyl)-1H-imidazol-3-ium bromide, which contains one phosphane, one pyridine and one imidazolium groups, of formula [o-Cy2PCH2(C5H3N)(o-C3H3N2DiPP)]Br and abbreviated as (CyPNpyrCim)Br, was previously shown to afford the Co(ii) complex [Co(CyP*NaCNHC)Br] (1) containing a dearomatised picolyl moiety in the tridentate, anionic donor ligand CyP*NaCNHC (Na = anionic amido, P* = vinylic P donor). We now report that formation of 1 is preceded by an intermediate tentatively assignable to the 5-coordinate Co(ii) complex [Co(CyPNpyrCNHC){N(SiMe3)2}Br] (2). The reaction of 1 with LiCH2SiMe3 afforded the dark purple, paramagnetic [Co(CyP*NaCNHC)CH2SiMe3] (3) with a low spin d7 CoII; the electronic configurations of 1 and 3 were corroborated by EPR spectroscopy. Addition of excess (≥4 equiv.) H2SiPh2 to a solution of 1 gave the diamagnetic [Co(CyP(SiHPh2)NCNHC)Br] (4) following Si-H activation and silylation of the ligand backbone at the α-CHP. Reduction of CoII to CoI by silanes is uncommon.

A novel preparation route for layered hydroxide based hybrid phases has been investigated combining the polyol route with the in situ generation of inorganic platelets, in the presence of an amphiphilic polymer as well as bola-amphiphiles. The polyol route consists of hydrolysis in an alcoholic medium containing acetate metal cations as precursor(s), to yield an LDH Zn 2 Al cation composition or LSH-Zn (layered single hydroxide). A bola amphiphile is described as hydrophobic polymer segment-telechelic-chains terminated by two anionic hydrophilic end groups, using volatile ammonium cations as counter ions. The impact of both process conditions as well as the chosen system with regard to the metal hydroxide framework on the morphology of the obtained hybrid phases is scrutinized by X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and compared to that of the corresponding physical mixture. For the ex situ approach, the diffusion of large cumbersome polymers or amphiphilic bolas between the inorganic platelets was found to be efficient, mostly driven by an anion exchange reaction between interleaved acetate anions and carboxylate functions of the molecular backbones, and keeping intact the inner sheet integrity through a topotactic process. In particular with LSH-Zn, a multi-stratified assembly has been observed combining an acetate pristine structure and a partly bola diffused structure, leading to a biphasic structure, aggregated and intercalated. To the best of our knowledge, observation of LSH-Zn single platelets has never been reported, making the combined process polyol/in situ an interesting new route to reach exfoliation. Indeed, it leads to the generation of either LSH or LDH platelets of lateral size ranging from 10 up to 200 nm. However, the platelets were found to be porous; it is considered as a drawback for barrier properties. It is our belief that such porosity may open new insights in "tectonic" architecture by intertwining 2D and 1D-type fillers. Rather counterintuitively, the ex situ approach based on a topotactic exchange reaction matches the in situ templating reaction in many cases as a function of the dispersion state regardless of the polymer or bolas as well as the platelet cation composition.

The advancement of molecular electronics and spintronics requires novel hybrid materials with synergistic magnetic and electrical properties. The non-covalent functionalization of highly conductive graphene with magnetically bistable spin crossover (SCO) complexes may yield such a multifunctional material. In this regard, a graphene-Fe(ii) SCO complex hybrid (Gr-SCO) has been prepared by non-covalently anchoring a pyrene decorated SCO complex with solution phase pre-exfoliated few-layer graphene sheets. SQUID magnetometry revealed the preservation of SCO in the Gr-SCO hybrid material exhibiting more gradual spin state switching characteristics than in the bulk molecular complex. This persistence of SCO of a molecular Fe(ii) complex upon anchoring on the graphene surface has consequences towards the realization of SCO based applications: in (i) reversible spin state dependent band gap tuning of graphene with an SCO complex analogous to chemical doping of graphene, and (ii) to probe the spin state dependence of electrical conductivity modulation by wiring the anchoring group (pyrene) tethered SCO complex between chemically robust few-layer graphene electrodes.

The design and synthesis of a novel family of molecular turnstiles T1-T5 were achieved. All five turnstiles are based on a stator and a rotor covalently interconnected. While turnstiles T1-T2 are based on a symmetric stator equipped with two coordinating pyridyl units and a rotor bearing either a pyridyl or p-dimethylaminopyridyl coordinating moiety, the two non-symmetric turnstiles T4 and T5 are based on a stator bearing only a single pyridyl unit and the same rotor as T1 and T2 mentioned above. The switching between the open (T1-T5) and the closed (T-M) states of the turnstiles by metal cations (M = Ag + or Pd 2+ ) was investigated in solution by using 1D and 2D NMR techniques. The locking of the rotational movement leading to the closed state of the turnstile was achieved upon addition of the Ag + cation through its simultaneous binding by both pyridyl moieties of the stator and the rotor. The unlocking process leading back to the open state was achieved by the addition of Et 4 NBr. For the symmetric turnstiles T1 and T2, bearing two pyridyl units on the stator, the binding of the Ag + cation leads to an oscillating phenomenon between the two energetically equivalent closed states. However, in the case of turnstile T1, the oscillating process could be prevented by blocking the rotational movement using PdCl 2 as the locking agent. Owing to the emissive nature of the stator, the open and closed states of the turnstiles were investigated by steady state and time-resolved photophysical methods. The photo-excitation of the turnstiles in their open state leads to an intense near-UV to deep-blue emission with short-lived excited states and a singlet intra-ligand charge transfer ( 1 ILCT) character. Upon binding of the Ag + cation, sizeable bathochromic shifts and a substantial decrease of PLQY were observed. Finally, the coordination of PdCl 2 , which possesses lower-lying excited states with metal-centered (MC) and ligand-to-metal charge transfer (LMCT) character, completely quenches the photoluminescence.

A series of mononuclear salen-supported gallium amido/alkoxide derivatives were prepared and structurally characterized and subsequently used as initiators in rac-lactide ring-opening polymerisation (ROP). The reaction of variously substituted salen ligands (1a-1f) with 0.5 equiv. of Ga 2 (NMe 2 ) 6 allowed the isolation of the corresponding (salen)Ga-NMe 2 chelates (2b-2d, 2f) via an amine elimination route, as poorly soluble compounds in common solvents. The (salen)Ga-OBn derivatives (3a-3e) may be readily accessed by an amine-elimination/alcoholysis sequence and the molecular structures of 3a, 3d and 3e were confirmed through X-ray crystallography diffraction analysis. The present (salen)Ga-X species may effectively mediate the iso-selective ROP of rac-LA in a controlled manner (P m up to 0.77 using a 1/1 2f/BnOH mixture as ROP initiator), with a ROP activity greatly dependent upon steric hindrance and geometrical constraints imposed by the variously substituted salen ligands. Based on the present study, salen ligands with limited steric hindrance and a certain degree of flexibility appear best suited for iso-selective ROP by (salen)Ga chelates. The salen-gallium complex 3a is also effective for the controlled ROP of ε-caprolactone (CL) and the production of PCL-b-PLA copolymers.

Complexes (bmim) 2 [Cu 3 (μ 3 -Cl) 2 (μ-pz) 3 Cl 3 ] (1), (bmim)[Cu 3 (μ 3 -OH)(μ-pz) 3 Cl 3 ] (2) and (bmim) 2 [Cu 3 (μ 3 -OH)(μ-Cl)(μ-pz) 3 Cl 3 ] (3) were synthesized (bmim + = 1-butyl-3-methylimidazolium, pz - = pyrazolato anion). Dianionic complexes 1 and 3 were obtained as crystalline solids, whereas the monoanionic complex 2 was obtained as a viscous paste. Magnetic susceptibility and X-band EPR studies revealed intramolecular ferromagnetic interactions for 1 with small magnetoanisotropy in its ground state (D 3/2 ∼ 10 -3 cm -1 ) and intramolecular antiferromagnetic interactions for 2 and 3 (-285 and -98 cm -1 average J, respectively) with important magnetic anisotropy in their ground states stemming from a combination of low magnetic symmetry and antisymmetric exchange interactions. Thermal studies revealed a clear melting point of 140 °C for 1, which is lower than that of its PPN + and Bu 4 N + analogues (1PPN and 1Bu 4 N, respectively, PPN + = bis(triphenylphosphine)iminium). Upon cooling, 1 remains molten down to 70 °C. Mixtures of the salts 1, 1PPN and 1Bu 4 N, exhibited modified melting behaviours, with the mixtures exhibiting lower melting points than those of either of their pure components.

An upper rim, o-(diphenylphosphinyl)phenyl-substituted calix[4]arene has been prepared and its coordinative properties investigated. When heated in the presence of palladium, the new biarylphosphine undergoes conversion into two diastereomeric, calixarene-fused phospholes. In both, the P lone pair adopts a fixed orientation with respect to the calixarene core. The more hindered phosphole (8), i.e. the one with the endo-oriented lone pair (cone angle 150°-175°), forms complexes having their metal centre positioned very near the calixarene unit but outside the cavity, thus inducing an unusual chemical shift of one of the methylenic ArCH 2 Ar protons owing to interactions with the metal centre. As expected for dibenzophospholes, the complex [Rh(acac)(CO)·8], when combined with one equivalent of free 8, efficiently catalyses the hydroformylation of styrene, the catalytic system displaying high regioselectivity in favour of the branched aldehyde (b/l ratio up to 30). The optical and redox properties of the derivatives have also been investigated.

Coordination cages obtained upon complexation of pyridyl functionalized porphyrins by Ag + disassemble when overtaking a 1 : 2 stoichiometric amount of silver salt. An excess of Ag + then leads to unusual chemical processes, here analyzed in detail, which permanently transform the monomeric porphyrins. The observed processes, discussed with reference to model compounds devoid of polyether substituted pyridyl residues, evidence a peculiar reactivity for meso 2,6-dimethylphenyl substituted porphyrins.

Kinetically unstable heteroleptic trans-bispalladacycles were isolated by using hemichelation. Three structures of trans isomers and five of cis isomers were characterized by X-ray diffraction analysis. The ready trans-to-cis isomerization of such hemichelates that was monitored by variable temperature NMR experiments is facilitated dynamically because the Pd(ii) center can preserve its square planar coordination in a rather low lying transition state, which was localized by methods of the density functional theory. This process is not achievable in the isomerization of conventional homoleptic trans-bispalladacycles since it involves the preliminary partial chelate decoordination and an unfavorable high-lying planar trigonal coordinated - or Y-shaped-Pd(ii) transition state according to DFT investigations.

New non-symmetrical, redox-active imino NHC pyridine pincer ligands, 2-(R 1 -imidazol-2-ylidene)-6-(R 2 N[double bond, length as m-dash]CH)-pyridine (R 1 = 2,6-diisopropylphenyl (DiPP), R 2 = 2,4,6-trimethylphenyl (Mes), 4B; R 1 = R 2 = DiPP, 4C), have been accessed by a Zn II -promoted modular synthesis involving the quaternization of R 1 -imidazole by [Zn(κN imine κN pyridine )(2-(R 2 N[double bond, length as m-dash]CH)-6-bromo-pyridine)Cl 2 ], followed by Zn II removal and deprotonation of imidazolium pro-ligands. Redox active forms of 4B were implicated in the two complexes obtained by its reaction with FeBr 2 /KC 8 ; metrical data analysis pointed to the occurrence of radical anionic and dianionic redox states of 4B.

The reactivity of the N-functionalized DPPA-type ligands (Ph 2 P) 2 N(p-Z)C 6 H 4 [Z = H (1a), SMe (1b), OMe (1c)] with AgBF 4 was investigated and revealed an unexpected influence of the para substituent Z of the N-aryl ligand. In acetone, the mononuclear bis-chelated [Ag{(1a-1c)-P,P} 2 ]BF 4 (2a·BF 4 -2c·BF 4 ) and dinuclear bridged [Ag 2 {μ 2 -(1a-1c)-P,P} 2 ](BF 4 ) 2 [3a·(BF 4 ) 2 -3c·(BF 4 ) 2 ] complexes were obtained with a 1 : 2 and 1 : 1 AgBF 4 /ligand molar ratio, respectively. While the molecular structures of 2a·BF 4 and 2b·BF 4 determined in the solid-state by X-ray diffraction revealed their mononuclear nature and the absence of cation/anion interaction, complexes 3b·(BF 4 ) 2 and 3c·(BF 4 ) 2 form 2D coordination polymers through intermolecular Ag-S or Ag-O interactions, respectively, involving the N-function of the respective DPPA-type ligand, and display direct interactions between one BF 4 anion and both Ag(i) cations. Surprisingly, the equimolar reaction between ligands 1a-1c and AgBF 4 in CH 2 Cl 2 led to different proportions of the dinuclear complexes 3a·(BF 4 ) 2 -3c·(BF 4 ) 2 and clusters [Ag 3 (μ 3 -Cl) 2 {μ 2 -(1b-1c)-P,P} 3 ]BF 4 (4b·BF 4 -4c·BF 4 ), depending on the nature of the para substituent Z of the N-aryl ligand. The trinuclear complexes resulted from C-Cl bond activation of the chlorinated solvent and were characterized by NMR spectroscopy and X-ray diffraction, and could be selectively produced by addition of 2/3 equiv. of [NMe 4 ]Cl to the corresponding dinuclear complexes or by a one-pot procedure involving the correct amount of each reagent. A series of experiments and kinetic NMR investigations were performed to gain further insight into the formation of the trinuclear Ag 3 Cl 2 core clusters.

Three Fe(iii) dimers, [Fe 2 (L-H) 2 ]·2CH 3 CN (1), [Fe 2 (L-OCH 3 ) 2 ] (2) and [Fe 2 (L-OC 2 H 5 ) 2 ]·2CH 3 CN (3), containing the pentadentate O,N,N,O,O-donor Schiff-base ligands with variable size pendants, were synthesized and structurally characterized. The three ligands were generated in situ from 2-(iminomethyl)phenol, 2-methoxy-6-(iminomethyl)phenol and 2-ethoxy-6-(iminomethyl)phenol, respectively. All three crystal structures contain centrosymmetric dimers of edge-sharing octahedra of Fe(iii) ions through a pair of μ 2 -phenoxido bridges. The exchange coupling is ferromagnetic for 1 (J = +0.47(1) cm -1 , ∠Fe-O-Fe = 98.02°) and 2 (J = +0.86(1) cm -1 , ∠Fe-O-Fe = 97.17°), but antiferromagnetic for 3 (J = -0.72(1) cm -1 , ∠Fe-O-Fe = 98.53°), which are correlated by high-field electron paramagnetic resonance revealing moderate magneto-anisotropy of D = -0.24(3) cm -1 , E = 0.08(1) cm -1 for 1, D = -0.38(1) cm -1 , E = 0.11(1) cm -1 for 2, and D = 0.30(3) cm -1 , E = 0.02(1) cm -1 for 3. The exchange couplings were further estimated by DFT calculations, which gave the finest Fe-O-Fe angle of 97.83° for the ferromagnetic-antiferromagnetic crossover.

The linear, two-coordinate and isostructural heteroleptic [M(IPr){N(SiMe 3 ) 2 }] (IPr = 1,3-bis(diisopropylphenyl)-imidazol-2-ylidene), formally M I complexes (M = Co, 3; Fe, 4) were obtained by the reduction of [M(IPr)Cl{N(SiMe 3 ) 2 }] with KC 8 , or [Co(IPr){N(SiMe 3 ) 2 } 2 ] with mes*PH 2 , mes* = 2,4,6-tBu 3 C 6 H 2 . The magnetism of 3 and 4 implies Co II and Fe II centres coupled to one ligand-delocalized electron, in line with XPS and XANES data; the ac susceptibility of 4 detected a pronounced frequency dependence due to slow magnetization relaxation. Reduction of [Fe(IPr)Cl{N(SiMe 3 ) 2 }] with excess KC 8 in toluene gave the heteronuclear 'inverse-sandwich' Fe-K complex 7, featuring η 6 -toluene sandwiched between one Fe 0 and one K + centre.

This manuscript describes the synthesis of a series of neutral titanium(iv) monomeric complexes constructed around a TiO 4 N 2 core. The two nitrogen atoms that compose the coordination sphere of the metallic center belong to 2,2'-bipyrimidine ligands homo-disubstituted in the 4 and 4' positions by methyl (2a), phenylvinyl (2b), naphthylvinyl (2c) or anthrylvinyl (2d) groups. The crystal structures of these complexes named [Ti(1) 2 (2a)], [Ti(1) 2 (2b)], [Ti(1) 2 (2c)] and [Ti(1) 2 (2d)] (where 1 is a 2,2'-biphenolato ligand substituted in the 6 and 6' positions by phenyl groups) are reported. The hydrolytic stability of the four complexes is evaluated by monitoring the evolution of the free 2a-d signals by 1 H NMR spectroscopy. For the conditions tested (6 mM, DMSO-d 6 /D 2 O: 8/1), a rather good stability with t 1/2 ranging from 180 to 300 min is determined for the complexes. In the presence of an acid (DCl), the hydrolysis of [Ti(1) 2 (2a)] is faster than without an acid. The cytotoxic activity against gastric cancer cells of the titanium-based compounds and the free disubstituted 2,2'-bipyrimidine ligands is tested, showing IC 50 ranging from 6.2 ± 1.2 μM to 274 ± 56 μM. The fluorescence studies of the ligands 2a-d, and the complexes [Ti(1) 2 (2a-d)] reveal an important fluorescence loss of the ligands 2c and 2d upon coordination with the Ti(1) 2 fragment. Frontier orbitals obtained by DFT calculations permit us to explain this fluorescence quenching.

A ligand derived from 1,3bpp (2-(pyrazol-1-yl)-6-(pyrazol-3-yl)-pyridine) has been prepared to prove that the spin crossover (SCO) of an Fe(ii) complex can be blocked by means of intramolecular interactions not related to the crystal field. Calculations show that the blocking is caused by the energy penalty incurred by the rotation of a phenyl ring, needed to avoid steric hindrance upon SCO.

A series of deep-red colored nano-sized titanium oxo-clusters bearing catecholato ligands is reported. These architectures are produced via post-synthetic modification of the Ti10O12(cat)8(py)8 (cat = catecholato, py = pyridine) complex through quantitative substitution of labile pyridine ligands by three substituted pyridines (pico, 4-Phpy and pyrald). The crystal structure analysis reveals a common Ti10O12(cat)8 backbone for the three isolated molecular architectures. Partial charge analysis indicates two types of titanium atoms within these complexes with one resembling titanium(iv) found in TiO2. These complexes strongly absorb visible light in solution (λmax = 411 nm, ε = 10 800 for Ti10O12(cat)8(py)8 in CHCl3) and in the solid-state. The band gaps estimated from the reflectance spectra are between 1.85 eV and 1.97 eV. The present work also details the HOMO and LUMO representations obtained via DFT calculation for Ti10O12(cat)8(py)8 and a virtual Ti10O12(cat)8 complex as well as the DOS (density of states) plots calculated for those structures. This computational study highlights an impact of the pyridine ligand on the DOS plots.

A series of P-NHC-type hybrid ligands containing both PR2 and N-heterocyclic carbene (NHC) donors on meta-bis-substituted phenylene backbones, L(Cy), L(tBu) and L(Ph) (R = Cy, tBu, Ph, respectively), was accessed through a modular synthesis from a common precursor, and their coordination chemistry with coinage metals was explored and compared. Metallation of L(Ph)·n(HBr) (n = 1, 2) with Ag2O gave the pseudo-cubane [Ag4Br4(L(Ph))2], isostructural to [Ag4Br4(L(R))2] (R = Cy, tBu) (T. Simler, P. Braunstein and A. A. Danopoulos, Angew. Chem., Int. Ed., 2015, 54, 13691), whereas metallation of ·HBF4 (R = Ph, tBu) led to the dinuclear complexes [Ag2(L(R))2](BF4)2 which, in the solid state, feature heteroleptic Ag centres and a 'head-to-tail' (HT) arrangement of the bridging ligands. In solution, interconversion with the homoleptic 'head-to-head' (HH) isomers is facilitated by ligand fluxionality. 'Head-to-tail' [Cu2Br2(L(R))2] (R = Cy, tBu) dinuclear complexes were obtained from L(R)·HBr and [Cu5(Mes)5], Mes = 2,4,6-trimethylphenyl, which also feature bridging ligands and heteroleptic Cu centres. Although the various ligands L(R)l ed to structurally analogous complexes for R = Cy, tBu and Ph, the rates of dynamic processes occurring in solution are dependent on R, with faster rates for R = Ph. Transmetallation of both NHC and P donor groups from [Ag4Br4(L(tBu))2] to AuI by reaction with [AuCl(THT)] (THT = tetrahydrothiophene) led to L(tBu) transfer and to the dinuclear complex [Au2Cl2L(tBu)] with one L(tBu) ligand bridging the two Au centres. Except for the silver pseudo-cubanes, all other complexes do not exhibit metallophilic interactions.

Attempts to evaluate experimentally the donor characteristics of the N,N'-bis(di-tert-butylphosphanyl)-imidazole-2-ylidene (PC(NHC)P) hybrid ligand are described. Thus, reactions of PC(NHC)P with [Rh(μ-Cl)(COD)]2 and [Rh(μ-Cl)(CO)2]2 led to the formation of the mononuclear and dinuclear complexes, [Rh(PC(NHC)P,κP,κC(NHC))2]Cl (PC(NHC)P-RhCl) and [Rh(CO)(PC(NHC),κP,κC(NHC),κN)]2 (PC(NHC)-RhCO), respectively, the latter resulting after in situ cleavage of one (t-Bu)2P-Nimid bond of PC(NHC)P. With ligands acting as a P,C-chelate, a straightforward evaluation of the Tolman electronic parameter (TEP) of the C(NHC) donor is problematical; the viability of dangling P- and bound C(NHC)-donors (i.e.κC(NHC)) has been observed in the trinuclear Fe(ii) chain complex [Fe3Cl2(μ-Cl)4(THF)2(PC(NHC)P,κC(NHC))2] (PC(NHC)P-Fe), obtained by the reaction of PC(NHC)P with [Fe4Cl8(THF)6] and, recently, established on Cr(II), Co(II) and Au(I) centres. Evaluation of the π-accepting properties of the PC(NHC)P (and the related Dipp-PC(NHC)) was based on the (77)Se NMR chemical shifts of the corresponding NHC-Se adducts, PC(NHC)P-Se (and Dipp-PC(NHC)-Se), which were prepared from the free PC(NHC)P (and Dipp-PC(NHC)) and Se. The π-acidity of PC(NHC)P is found to be higher than that of Dipp-PC(NHC) but lower than that of SIPr. The donor ability of the C(NHC) in PC(NHC)P was explored by its reaction with the Lewis acids tris(pentafluorophenyl)borane (B(C6F5)3) and tris(pentafluorophenyl)boroxine ([(C6F5)BO]3), which resulted in stable donor-acceptor adducts with no FLP reactivity. The steric properties of PC(NHC)P and Dipp-PC(NHC) are conformation dependent, with the percent buried volume (%Vbur) of PC(NHC)P in the structurally characterised conformer calculated at 67.6, the largest value currently reported for NHC ligands.

Double deprotonation of 2,6-bis-(di-tert-butylphosphinomethyl)-pyridine ((tBu)PN(tBu)P), with KCH2C6H5 afforded K2((tBu)P*Na(tBu)P*), Na = anionic amido N, (tBu)P* = di-tert-butyl vinylic P donor. The analogous [Li2((tBu)P*Na(tBu)P*)]2 (1) was reacted with [CrCl2(THF)2] and [ZrCl4(THT)2] to give the helical [Cr{Cr((tBu)P*Na(tBu)P*)Cl}2] (2) and [Zr((tBu)P*Na(tBu)P*)Cl2] (3), respectively. DFT calculations support dearomatisation of P*NaP* and its high donor ability.

In organometallic chemistry the commonly known Sidgwick-Langmuir 18 electron rule is constantly being probed for further discovery of molecular compounds that arise as exceptions. The present study examines the formation and the structure of three novel hemichelates of Pd(ii) derived from the reaction of in situ-formed indene and hydrophenanthrene-based organometallic anions with three different μ-chloro-bridged palladacycles. Electronic structure and interaction behavior have been calculated with methods of the density functional theory at the (ZORA) MetaGGA-D TPSS-D3(BJ), GGA-D PBE-D3(BJ), and hybrid PBE0-dDsC dispersion corrected levels, all with the implementation of all electron triple zeta single polarization basis set. A particular focus of the theoretical investigation was made on the nature of the interaction between the [Cr(CO)3] moiety and the Pd(ii) centers, which according to X-ray diffraction analyses lack significant incipient bridging COPd character. Structures were further assessed - Natural Bonding Orbitals (NBO), Quantum Theory of Atoms in Molecules (QTAIM), and Extended Transition State with Natural Orbitals for Chemical Valence (ETS-NOCV) analysis methods. As a result, intramolecular interactions of interest, primarily around the Pd atom, were analyzed as a measure of natural atomic orbital (NAO) contributions to the natural bonding orbital (NBO) formation, QTAIM analysis with special attention to the bonding critical points (BCPs), as well as energetic analysis of intramolecular interaction forces by Energy Decomposition Analysis (EDA). Theoretical analyses confirm that attractive electrostatics dominate the stabilization of Pd(ii) hemichelates. In the case of complexes , and we expand the known amount of 14 electron transition metal complexes that can be synthesized via reliable synthetic methods. However, complex presented some means of stability but was more reactive to moisture and air under laboratory conditions and escaped thorough analytical characterization.