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Positively charged ligands are scarce. Here, we report the synthesis of unprecedented cationic selenium-containing triazapentadiene ligand framework. The reaction between 2-pyridylselenyl reagents and NaN(CN)2in a 2:1 ratio produces the sodium complexes featuring the cationic selenium-containing triazapentadiene (SeTAP) ligand. The sodium-to-metal transmetalation allows facile preparation of SeTAP metal complexes, as exemplified by the reactions with CuCl2, AgNO3, NaAuCl4, and FeCl3. Density functional theory calculations have been used to analyze and characterize the chalcogen bonding interactions observed in the solid state for these compounds. Moreover, antifungal properties of the SeTAP ligand and its metal complexes were screened for in vitro activity against several phytopathogenic fungi. Phoma eupyrenaexhibited prominent sensitivity against the action of most of the tested compounds.

Four manganese(III) complexes, [MnL1Cl] (1), [MnL2Cl] (2), [Mn2(L2)2(N3)2] (3), and [Mn2(L1)2(NCS)2] (4){H2L1= N,N′-bis(5-chlorosalicylidene)-1,3-diaminopropane, H2L2= N,N′-bis(5-chlorosalicylidene)-2,2-dimethyl-1,3-diaminopropane} have been synthesized and characterized. The structures of the complexes were confirmed by single-crystal X-ray diffraction analysis. All four complexes showed a tendency to form supramolecular dimers in the solid state. Density functional theory (DFT) calculations have been used to investigate the supramolecular assemblies observed in the solid state of these complexes and to characterize the Mn···O interactions in terms of covalent/noncovalent nature and their importance for the formation of self-assembled dimers in complexes 1–4. QTAIM and NCIPlot calculations have been used to disclose the noncovalent nature of the Mn···O contacts in complexes 1–4, which can be considered as matere bonds (MaBs) instead of coordination bonds. Such a type of matere bond is unprecedented in square pyramidal Mn complexes. Energetically, the MaBs exhibit values ranging from −8 to −11 kcal/mol across these complexes. Therefore, this research highlights the attractive interactions between group 7 Mn(III) derivatives and Lewis bases involving a π-hole formed opposite one of the apical coordination bonds.

Through the interaction of a halogen bond donor (1,4-diiodotetrafluorobenzene; 1,4-FIB) with isomers of pyridyl-substituted nitronyl nitroxides (Py-NN), five novel cocrystals were constructed via halogen bonding. The cocrystals (pPy-NN)n·1,4-FIB (n= 1, 2, 4) and (mPy-NN)n·1,4-FIB (n= 1, 2) are represented by the discrete clusters Py-NN·1,4-FIB·NN-Py, cyclic tetrameric structures (pPy-NN)4·(1,4-FIB)4, or one-dimensional (1D) zigzag chains. Density functional theory calculations were used to analyze the nature of the halogen bonds and to compare the strengths of I···NPy and I···ONO interactions. The halogen bonds were shown to be quite strong, ranging from 6.4 to 9.0 kcal/mol, according to the QTAIM analysis. In addition, quantum chemical analyses revealed relatively weak exchange interactions of both ferromagnetic and antiferromagnetic nature, indicating a modulating effect of the halogen bonding on magnetic properties. These findings point to the potential usefulness of halogen bonding interactions for promoting the self-assembly of stable organic radicals for further use in the preparation of exchange-coupled organic spin systems.

In parallel to the nature of the chalcogen atom (Ch) and nucleophile (Nu), the strength and directionality of chalcogen bonding (ChB) are also dependent on the electron donor or acceptor character of the functional group (R) at ∠R–Ch···Nu. Although Hammett’s para-substituent constant (σp) can be used for the quantitative description of substituent effects, herein, we found that due to participation of the substituents in various types of intermolecular interactions, there is no linear relationship between the σpof the substituent in R (X = −CH3, −H, −F, −Cl, −Br, and −NO2) and the experimental Se···N distance or ∠N–Se···N angle in 5-substituted benzo[c][1,2,5]selenadiazoles and their copper(II) complexes. Such a relationship is also not observed theoretically, which is rationalized by taking into consideration the formation of intramolecular hydrogen and chalcogen bonds in the Cu complexes. The chalcogen bonds have been analyzed using the quantum theory of “atoms in molecules” combined with the noncovalent interaction plot and energy decomposition analysis.

Noncovalent interactions and the coordination bond-assisted capture of Pd(0) in supramolecular cavities of bis(2,4-bis(trichloromethyl)-1,3,5-triazapentadienato)-Pd(II) is reported. It was determined that the cooperation of a coordination bond and noncovalent interactions in the Pd(II)-mediated activation of a nitrile group at 2,2,2-trichloroacetonitrile or 2,2-dihaloacetonitrile in the presence of NH4OH or propan-2-one oxime in acetone, DMF, DMSO, or MeOH leads to various organic, supramolecular, and coordination compounds.

The design of the secondary coordination sphere of metal complexes has emerged as a powerful synthetic strategy in their application/function in catalysis, molecular recognition, and crystal engineering. In contrast to traditional approaches, herein, the secondary coordination sphere of copper(II) complexes was designed by using chalcogen (sulfur) bond donor auxiliary ligands (5-substituted-1,3,4-thiadiazol-2-amines) in one-pot activation of one nitrile group in an arylhydrazone ligand. The chalcogen bond donor ability of the auxiliary ligands markedly increases with the electron-withdrawing character of the substituents, as disclosed by X-ray diffraction and theoretical studies.

Progress with fluorescent flippers, small-molecule probes to image membrane tension in living systems, has been limited by the effort needed to synthesize the twisted push–pull mechanophore. Here, we move to a higher oxidation level to introduce a new design paradigm that allows the screening of flipper probes rapidly, at best in situ. Late-stage clicking of thioacetals and acetals allows simultaneous attachment of targeting units and interfacers and exploration of the critical chalcogen-bonding donor at the same time. Initial studies focus on plasma membrane targeting and develop the chemical space of acetals and thioacetals, from acyclic amino acids to cyclic 1,3-heterocycles covering dioxanes as well as dithiolanes, dithianes, and dithiepanes, derived also from classics in biology like cysteine, lipoic acid, asparagusic acid, DTT, and epidithiodiketopiperazines. From the functional point of view, the sensitivity of membrane tension imaging in living cells could be doubled, with lifetime differences in FLIM images increasing from 0.55 to 1.11 ns. From a theoretical point of view, the complexity of mechanically coupled chalcogen bonding is explored, revealing, among others, intriguing bifurcated chalcogen bonds.

The synthesis of fluorescein propargyl diether (L) and two different dinuclear gold(I) derivatives containing a water-soluble phosphane [1,3,5-triaza-7-phosphatricyclo[3.3.1.13.7]decane (PTA) for complex 1and 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) for complex 2] has been successfully performed. All compounds display intrinsic emission from fluorescein, being less intense for gold(I) complexes due to the heavy-atom effect. All compounds aggregate in acetonitrile/water mixtures with the formation of larger aggregates for those samples containing more water content, as evidenced by dynamic light scattering and small-angle X-ray scattering experiments, in agreement with the absorption and emission data. The emission of the samples increases when they are used to obtain luminescent materials with four different organic matrices [poly(methyl methacrylate, polystyrene (PS), cellulose, and Zeonex]. The compounds display very high values of singlet oxygen (1O2) production in dichloromethane. Singlet oxygen production was also evaluated in the doped matrices, being the highest in PS and with an exciting increase on PS microspheres. Density functional theory (BP86-D3) and GFN2-xTB calculations were used to model the assembly of Land complexes 1and 2with the different organic matrices and rationalize the experimental findings based on the geometries, molecular electrostatic potential surfaces, and complementarity and HOMO–LUMO gaps.

Cationic imidazoliumyl(phosphonio)-phosphanides [LC–P–PR3]+(1a–e+, LC= 4,5-dimethyl-1,3-diisopropylimidazolium-2-yl; R = alkyl, aryl) are obtained via the nucleophilic fragmentation of tetracationic tetraphosphetane [(LC–P)4][OTf]4(2[OTf]4) with tertiary phosphanes. They act as [LC–P]+transfer reagents in phospha-Wittig-type reactions, when converted with various thiocarbonyls, giving unprecedented cationic phosphaalkenes [LC–P═CR2]+(5a-f[OTf]) or phosphanides [LC–P–CR(NR2′)]+(6a-d[OTf]). Theoretical calculations suggest that three-membered cyclic thiophosphiranes are crucial intermediates of this reaction. To test this hypothesis, treatment of [LC–P–PPh3]+with phosphaalkenes, that are isolobal to thioketones, permits the isolation of diphosphirane salts 11a,b[OTf]. Furthermore, preliminary studies suggest that the cationic phosphaalkene [LC–P═CPh2]+may be employed to access rare examples of η2–P═C π-complexes with Pd0and Pt0when treated with [Pd(PPh3)4] and [Pt(PPh3)3] for which analogous complexes of neutral phosphaalkenes are scarce. The versatility of [LC–P]+as a valuable P1building block was showcased in substitution reactions of the transferred LC-substituent using nucleophiles. This is demonstrated through the reactions of 5a[OTf] and 6c[OTf] with Grignard reagents and KNPh2, providing a convenient, high-yielding access to MesP═CPh2(16) and otherwise difficult-to-synthesize 1,3-diphosphetane 17and P-aminophosphaalkenes.

The simultaneous binding of a molecular entity through two interactions is a frequently pursued recognition mode due to the advantages it offers in securing molecular self-assembly. Here, we report how the planarity of the benzothienoiodolium (BTI) cation allows for preorganizing in the cation plane the hydrogen, halogen, and chalcogen bonds (HBs, XBs, and ChBs, respectively) formed by the phenyl hydrogen, iodolium iodine, and thienyl sulfur. Crystallographic analyses of some BTI salts show how this interaction coplanarity enables their coupling to point toward a single anion that is coordinated via the supramolecular and heteroditopic synthon XB/HB or XB/ChB, the latter observed here for the first time. These synthons adopt a Janus-like arrangement around iodine. Crystallographic information suggests that interactions of the synthons act synergistically, e.g., when resulting in the unusually short ChBs formed by the thienyl sulfur. Determination of the molecular electrostatic potential, Bader’s quantum theory of “atoms-in-molecules” analysis, and natural bond orbital investigations give information on the nature and energetic aspects of the short contacts observed in crystals.

The importance of tetrel bonds (TtBs) in spontaneous self-assembly has been highlighted in two new lead(II) complexes: i.e. Pb[S2P{OC6H4(4-C(CH3)3)}2]2(1) and Pb[S2P{OC6H4(4-C2H5)}2]2(2), which were successfully isolated and characterized by FT-IR, UV–vis and multinuclear NMR (31P, 1H and 13C) spectroscopy. The structures of both complexes have been confirmed by single-crystal X-ray diffraction analyses. Interestingly, lead is coordinated by three sulfur atoms in 1but by four sulfur atoms in 2, due to stereochemically active lone pair electrons, thus leading to trigonal-pyramidal and tetragonal-pyramidal geometries, respectively. Complex 1is the first example of a lead(II) dithiophosphate wherein the lead(II) center is coordinated to three S atoms. These complexes are stabilized at a lower coordination number and display hemidirected structures that allow forming σ-hole bonds. The lead(II) center establishes short contacts with sulfur atoms to form Pb···S TtBs that contribute to the construction of a self-assembled dimer in 1but to a supramolecular polymer in 2. The supramolecular assemblies are further stabilized by Pb···π TtB interactions. The attractive nature of TtBs has been studied by DFT calculations and characterized using a combination of Bader’s quantum theory of atoms-in-molecules (QTAIM) and noncovalent interaction plot (NCI plot) index based on a reduced density gradient (NCI-RDG) analysis. A systematic Hirshfeld surface analysis facilitates a comparison of intermolecular interactions such as C–H···π, π···π, Pb···S, and Pb···π in both complexes, which play a crucial role in the crystal engineering.

A novel [3+2] cycloaddition reaction between 2-pyridylselenyl halides or trifluoroacetates and isocyanates is described herein. This new convenient methodology allows the synthesis of novel 3-oxo-1,2,4-selenodiazolium scaffolds, which are inaccessible by the known methods. The coupling proceeds efficiently for a broad scope of substrates under mild conditions and allows preparation of cationic 3-oxo-1,2,4-selenodiazolium salts in high yields. The mechanism was analyzed using DFT calculations, evidencing the concerted nature of the novel cycloaddition reaction. The new Se-containing heterocycles were demonstrated to be structurally easily tunable donors of the chalcogen bonding (ChB). Noncovalent interactions in the solid state were studied using DFT calculations, molecular electrostatic potential surfaces and the quantum theory of atoms-in-molecules.

A typical halogen bond (HaB) donor, 1,4-dibromo-2,3,5,6-tetrafluorobenzene (FBB), was cocrystallized with the isocyanide CNMes and the cyanide NCMes to give two isostructural cocrystals, (CNMes)·FBB and (NCMes)·FBB. Their solid-state architecture exhibits a close similarity between the isocyanide and cyanide groups in their HaB-accepting role. This similarity and particular bonding features of the HaBs were additionally verified by theoretical calculations (molecular electrostatic potential analysis, electron density/electrostatic potential profiles, atoms-in-molecules charge analysis, and calculations of pKavalues and binding energies). Remarkably, both cocrystals form unusual heterohexamers where one Br atom of FBB simultaneously forms four contacts with two C (or N) and two Br atoms of neighboring molecules. On the basis of the geometric parameters and the theoretical data, these contacts can be defined as five-center tetrafurcated μ4-Br···(C, Br, C, Br) and μ4-Br···(N, Br, N, Br) HaBs; this is the first observation of the tetrafurcated HaB involving four disunited HaB acceptors.

Four new heterometallic Cu(II)–U(VI) species, [{(CuL1)(CH3CN)}UO2(NO3)2] (1), [{(CuL2)(CH3CN)}UO2(NO3)2] (2), [{(CuL3)(H2O)}UO2(NO3)2] (3), and [UO2(NO3)2(H2O)2]·2[CuL4]·H2O (4), were synthesized using four different metalloligands ([CuL1], [CuL2], [CuL3], and [CuL4], respectively) derived from four unsymmetrically dicondensed N,O-donor Schiff bases. Single-crystal structural analyses revealed that complexes 1, 2, and 3have a discrete dinuclear [Cu–UO2] core in which one metalloligand, [CuL], is connected to the uranyl moiety via a double phenoxido bridge. Two chelating nitrate ions complete the octa-coordination around uranium. Species 4is a cocrystal, where a uranyl nitrate dihydrate is sandwiched between two metalloligands [CuL4] by the formation of strong hydrogen bonds between the H atoms of the coordinated water molecules to U(VI) and the O atoms of [CuL4]. Spectrophotometric titrations of these four metalloligands with uranyl nitrate dihydrate in acetonitrile showed a well-anchored isosbestic point between 300 and 500 nm in all cases, conforming with the coordination of [CuL1], [CuL2], [CuL3], and the H-bonding interaction of [CuL4] with UO2(NO3)2. This behavior of [CuL4] was utilized to selectively bind metal ions (e.g., Mg2+, Ca2+, Sr2+, Ba2+, and La3+) in the presence of UO2(NO3)2·2H2O in acetonitrile. The formation of these Cu(II)–U(VI) species in solution was also evaluated by steady-state fluorescence quenching experiments. The difference in the coordination behavior of these metalloligands toward [UO2(NO3)2(H2O)2] was studied by density functional theory calculations. The lower flexibility of the ethylenediamine ring and a large negative binding energy obtained from the evaluation of H bonds and supramolecular interactions between [CuL4] and [UO2(NO3)2(H2O)2] corroborate the formation of cocrystal 4. A very good linear correlation (r2= 0.9949) was observed between the experimental U═O stretching frequencies and the strength of the equatorial bonds that connect the U atom to the metalloligand.

Two phosphorescent PtII-based cyclometalated complexes were co-crystallized with perfluorinated arenes to give 1:1 co-crystals. The X-ray study revealed that each of the complexes is embraced by arenesFto give infinite reverse sandwich structures. In four out of six structures, a dz2orbital of PtIIis directed to the arenesFring via π-hole···dz2[PtII] interactions, whereas in the other two structures, the filled dz2orbital is directed toward the arene C atoms. Computed molecular electrostatic potential surfaces of the arenesFand the complexes, noncovalent interaction indexes for the co-crystals, and natural bond orbital calculations indicate that π-hole···dz2[PtII] contacts (and, generally, the stacking) are of electrostatic origin. The solid-state photophysical study revealed up to 3.5-fold luminescence quantum yield and 15-fold lifetime enhancements in the co-crystals. This increase is associated with the strength of the π-hole···dz2[PtII] contact that is dependent on the π-acidity of the areneFand its spatial characteristics.

Salts and ionic cocrystals simultaneously comprising N-oxide and carboxylic acid functional groups constitute a very fertile ground for the investigation of various proton transfer phenomena. This is because such compounds combine two types of proton transfer: that is, inter- and intramolecular hydrogen bonding in acid–base systems. To this end, a series of novel salts based on pyridine-2,5-dicarboxylic acid N-oxide (H2pydco) as an organic acid and 2,4,6-triamino-1,3,5-triazine (tata), 2-aminopyrimidine (2a-pym), 2-amino-6-methylpyridine (2a-6mpy), 1,10-phenanthroline (phen), and 9-aminoacridine (9a-acr) as organic bases have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction: (Htata)+(Hpydco)−(1), (H2a-pym)+(Hpydco)−(2), (H2a-6mpy)+(Hpydco)−(3A,B), [(Hphen)+(Hpydco)−](H2pydco) (4), and [(H9a-acr)+(Hpydco)−]·EtOH (5). The unit cells of 3Aand 3Bdiffer slightly; however, 3Acrystallizes in a chiral orthorhombic space group P212121, while 3Bcrystallizes in the achiral space group P21/n. In both cases, the asymmetric unit comprises one cation and one anion. The influence of different organic cations on the packing of Hpydco–in the crystal lattice is studied. The most important feature of these crystals is the presence of extensive O–H···O, N–H···O, N–H···N, and C–H···O hydrogen bond networks, which form base-dependent supramolecular synthons: 1, 2, and 3A,Bcomprise an α-aminopyridinium moiety, and all involve the hydrogen-bonded motif R22(8) with the Hpydco–anion. Compounds 4and 5, which lack the α-aminopyridinium moiety, reveal different hydrogen-bonding patterns. The interaction energies of each individual hydrogen bond have been estimated using the quantum theory of “atoms-in-molecules”, which led us to the identification of the energetically favorable antielectrostatic N–H···N hydrogen bonds (stabilization energy of 4.0 kcal/mol) between positively charged melaminium species in 1. It has been also established that charge-assisted hydrogen bonding does not always offer an energetic advantage over “noncharged” hydrogen bonds. With the use of Hirshfeld surface (HS) analysis we have also explored the influence of the protonation state of pydco species on the composition of contact contributions, as well as established specific properties of their 2D fingerprint plots. Finally, a comment is provided on the applicability of HS analysis for the exploration of polymorphs featuring intramolecular proton transfer.

A novel nanosized porous supramolecular nonanuclear complex [Pb9(HL)12Cl2(ClO4)](ClO4)3·15H2O·a(solvent) (1·15H2O·a(solvent)) is reported that was synthesized by electrochemical oxidation of a Pb anode under the ambient conditions in a CH3CN:MeOH solution of N′-phenyl(pyridin-2-yl)methylene-N-phenylthiosemicarbazide (H2L), containing [N(CH3)4]ClO4as a current carrier. The supramolecular aggregate of 1is enforced by a myriad of Pb···S tetrel bonds (TtBs) established with the thiocarbonyl sulfur atoms of adjacent species, which have been also analyzed by DFT calculations via 2D maps of ELF, Laplacian and RDG properties. Moreover, Pb···Cl TtBs with the central Cl–anion, and Pb···O TtBs with the three oxygen atoms of the ClO4–anion, were revealed. Notably, the molecular structure of 1differs significantly from that recently reported by us [Pb2(HL)2(CH3CN)(ClO4)2]·2H2O (2·2H2O), which was obtained using a conventional synthetic procedure by reacting Pb(ClO4)2with H2Lin the same CH3CN:MeOH solution, thus highlighting a crucial role of the electrochemical conditions. The optical characteristics of the complex were investigated using UV–vis spectroscopy and spectrofluorimetry in methanol. The complex was found to be emissive when excited at 304 nm, producing a broad emission band ranging from approximately 420 to 600 nm with multiple peaks. The CIE-1931 chromaticity coordinates, calculated as (0.33, 0.24), suggest that the emission lies in the white region of the chromaticity diagram. Further investigation is needed to fully characterize the origin of this emission.

The isolation of isomeric complexes trans-[RuIILPyHPQ(CO)(PPh3)Cl] 2and cis-[RuIILPyHPQ(CO)(PPh3)Cl] 3, (Cl and PPh3are trans in 2and they are cis in 3respectively) as well as [RuIILPyHPQ(CO)(PPh3)2Cl] 4and [RhIIILPyHPQ(PPh3)Cl2] 5disclose the flexidentate nature of the multifunctional ligand, HLPyHPQ2-pyridylhydrazinophenanthrenequinone, 1. These complexes are maneuvered as molecular templates for understanding the role of halogen bonds (XB) in M–Cl bond activation and subsequent cleavage processes. Both isomeric forms 2and 3furnish trans-[RuIILPyHPQ(CO)(PPh3)(I3)] 6(where PPh3and I3–in trans position) when they are treated separately with I2in a hydrocarbon solvent. Nonetheless, complex 5is converted to 7upon similar treatment but 4remains unreacted. Crystal structure of 7revealed that it is composed of 62% trans-[RhIIILPyHPQ(PPh3)Cl(I3)] and 38% trans-[RhIIILPyHPQ(PPh3)Cl(ClI2)] (where PPh3and I3–/ClI2–are trans). The I3–/ClI2–gets coordinated to metal centers exclusively in an end-on fashion in all cases. Since the valence state of metal centers remains unaltered in due course of the reaction, the emergence of M–I3/M–ClI2from M–Cl in the absence of any reductant in solution is indicative of prior activation of M–Cl bond viathe formation of Halogen Bond (XB) of type [M–Cl–I–I] in an intermediate step. The geometrical fluctuations around the coordination sphere during the transformation of cis-[RuIILPyHPQ(CO)(PPh3)Cl] 3to trans-[RuIILPyHPQ(CO)(PPh3)(I3)] 6is reminiscent of the active influence of XB, triggering the isomerization of 3to 2owing to steric encumbrance, before it is being converted to 6. Electrochemical behavior and optoelectronic properties of the complexes have been complimented by theoretical analysis and the structures were characterized by SCXRD. Repeated π-stacking motifs in the crystalline phase architecture of the complexes have been scrutinized using DFT calculations.

The experimental realization of a variety of multimetallic systems composed by transition metals (TM) and heavier pnictogens has been widely explored via σ-bond activation of dipnictanes (Pn2R4), or even poly pnictanes (cyclo-(RnPn)n, Pn = Sb and Bi and R = any substituent). In contrast, isolation of stable metallacyclic rings viaTM-mediated activation of Sb and Bi multiple bonds are underexplored. Here, we reported the reactivity of “Sb = Sb” and “Bi = Bi” compounds with Jonas’ complex (CpCo(C2H4)2, Cp = C5H5) as the key electrophile to generate the “Co-Pn2” unit. Further exploiting of the synthetic potential of complex 2using various reagents led to a series of stable multimetallic compounds (5, 6, and 7) containing low-valent heavy pnictogens. These findings have been supported by a thorough investigation of the electronic features of these multimetallic complexes.

Cocrystallization of CuI with NCNMe2in the presence of 1,4-diiodotetrafluorobenzene (1,4-FIB) and 1,4-dibromotetrafluorobenzene (1,4-FBrB) in MeCN gave cocrystals [Cu4I4(NCNMe2)4]·1,4-FIB, [Cu4I4(NCNMe2)2(NCMe)2]·1,4-FIB, and [Cu4I4(NCNMe2)4]·1,4-FBrB, whose solid-state structures were studied by X-ray diffraction. In these three cases, the perfluorinated haloarenes function as combined σ- and π-hole donors, and their crystal structures exhibit intermolecular contacts, including halogen bonding (HaB) and π-hole interactions with the iodine ligands of the copper clusters. Analysis of the theoretical calculation data indicated that the formation of (cubane)·(perfluorinated haloarene) π–hole dimer is slightly energetically more favorable than (cubane)·(perfluorinated haloarene) HaB-based σ-hole dimer. The π-hole contacts and HaBs are accompanied by additional hydrogen bonding and also π-hole(NCN)···X (X = Br, I) contacts. Altogether, these interactions lead to the occurrence of moderately strong noncovalent binding between copper clusters and the aromatic HaB donors.

Cocrystallization of the dimeric [Cu2(μ-I)2(CNXyl)4] (Xyl = 2,6-Me2C6H3, 1) and polymeric catena-[Cu(μ-I)(CNC6H3-2-Cl-6-Me)2] (2) complexes with I2at different molar ratios between the reactants resulted in a series of (RNC)2CuI-based crystal polyiodides formed along with gradual accumulation of iodine, namely the cocrystals [1·I2]·[Cu(μ1,1-I3)(CNXyl)2]2followed by the generation of [Cu(μ1,3-I3)(CNXyl)2]2·2I2(5·2I2) or [Cu(μ1,1-I3)(CNC6H3-2-Cl-6-Me)2]2and then [Cu(μ1,3-I3)(CNC6H3-2-Cl-6-Me)2]n·n/2I2. The polyiodide 5·2I2exhibits a novel supramolecular motif─a purely inorganic halogen-bonded Cu2(μ1,3-I3)2core in the chair conformation. The X-ray structure of 5·2I2featuring I···I contacts was analyzed by a set of theoretical methods and attributed to moderately strong halogen bonding (from −3.2 to −3.9 kcal/mol); these interactions determine the supramolecular architecture of 5·2I2.

Co-crystallization of the push–pull nitriles NCNR2(R2= Me21, C4H82, C5H103, and C4H8O 4) with iodo-substituted perfluorobenzenes (1,4-diiodotetrafluorobenzene − 1,4-FIB and 1,3,5-triiodotrifluorobenzene − 1,3,5-FIB) gave cocrystals 1·1,3,5-FIB, 2·1,3,5-FIB, 3·1/2(1,4-FIB), 4·1/2(1,4-FIB), and 4·2(1,3,5-FIB), which were studied by single-crystal X-ray diffractometry (XRD). The structure-directing I···sp-Nnitrilehalogen bond (HaB) in all cocrystals was identified based on the consideration of the XRD geometrical (bond length and angles) parameters and also by Hirshfeld surface analysis, whereupon the observed HaBs were analyzed theoretically. The HaB-accepting role of the push–pulling dialkylcyanamides NCNR2and conventional nitriles NCR (R = Alk) was examined and compared in detail using, as model examples, the structures of cocrystals 3·1/2(1,4-FIB) (this work) and AdCN·1/2(1,4-FIB) (CSD refcode: KIHROL). These two cocrystals, which display similar supramolecular organization, were studied by several quantum chemistry methods including molecular electrostatic potential surface analysis, the natural bond orbital analysis, the quantum theory of atoms in molecules combined with the NCIPlot approach, and also by the Kitaura–Morokuma energy decomposition approach. While AdCN is a slightly poorer sp-N electron donor than the push–pull nitrile 3, HaBs in the cocrystals exhibit similar interaction energies. Although in the covalent chemistry the two types of nitriles often exhibit strikingly different reactivity patterns, the σ-hole-based I···sp-Nnitrilenoncovalent interaction provided the leveling effect, resulting in significant similarities between the HaB situations for both nitrile species.

A mononuclear uranyl complex, [UO2L] (1), has been synthesized with the ligand N,N′-bis(3-methoxy-2-hydroxybenzylidene)-1,6-diamino-3-azahexane (H2L). The complex showed a reversible U(VI)/U(V) redox couple in cyclic voltammetric measurements. The reduction potential of this couple showed a positive shift upon the addition of redox-inactive alkali- and alkaline-earth Lewis acidic metal ions (Li+, Na+, K+, Ca2+, Sr2+, and Ba2+) to an acetonitrile solution of complex 1. The positive shift of the reduction potential has been explained on the basis of the Lewis acidity and internal electric-field effect of the respective metal ions. The bimetallic complexes [UO2LLi(NO3)] (2), [UO2LNa(BF4)]2(3), [UO2LK(PF6)]2(4), [(UO2L)2Ca]·(ClO4)2·CH3CN (5), [(UO2L)2Sr(H2O)2]·(ClO4)2·CH3CN (6), and [(UO2L)2Ba(ClO4)]·(ClO4) (7) have also been isolated in the solid state by reacting complex 1with the corresponding metal ions and characterized by single-crystal X-ray diffraction. Density functional theory calculations of the optimized [UO2LM]n+complexes have been used to rationalize the experimental reduction and electric-field potentials imposed by the non-redox-active cations.

A discrete π-hole···σ-hole dimer is synthesized and X-ray characterized. It presents a perfect thumbtack geometry where the σ-hole of the linear [AuI2]−anion points to the π-hole located above the central Au-atom of the [AuI4]−anion. Such discrete π-hole···σ-hole dimers are unprecedented in literature, since all mixed-valence gold(I/III) iodide compounds reported to date form infinite ···([AuI4]−···[AuI2]−)n·· chains in the solid state. If an excess of iodine is used for the synthesis, triiodide [I3]−ions are partially incorporated into the [AuI2]−sites, forming infinite chains. The nature of the anion···anion interaction has been studied considering two possibilities: (i) a π-hole coinage bond or (ii) σ-hole halogen bond using high-level density functional theory calculations, the quantum theory of atoms in molecules, and the noncovalent interaction plot index.

Three isomeric zinc bisporphyrins have been prepared by covalently linking together two aminoporphyrins with an isophthalic acid derivative. The porphyrins differ in the substitution pattern on the mesophenyl groups, that is, ortho, meta, or para. Titrations carried out by UV‐visible and 1H NMR spectroscopy have been used to map out the stabilities and the stoichiometries of the complexes formed with 1,4‐diazabicyclo[2.2.2]octane (DABCO) in chloroform. The ortho‐and meta‐substituted bisporphyrins form 1:1 intramolecular sandwich complexes. The para‐substituted bisporphyrin cannot adopt the cofacial conformation required for this type of complex and forms a higher order 2:2 intermolecular assembly, which is stable over a wide range of DABCO concentrations.

This communication describes a self assembled porphyrin sphere. The globular macromolecular assembly contains 12 terminal porphyrins and has a molecular mass in excess of 15000 g mol−1.