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To explore the operational role of noncovalent interactions in supramolecular architectures with designed topologies, a series of solid‐state structures of 2‐ and 4‐formylphenyl 4‐substituted benzenesulfonates was investigated. The compounds are 2‐formylphenyl 4‐methylbenzenesulfonate, C14H12O4S, 3a, 2‐formylphenyl 4‐chlorobenzenesulfonate, C13H9ClO4S, 3b, 2‐formylphenyl 4‐bromobenzenesulfonate, C13H9BrO4S, 3c, 4‐formylphenyl 4‐methylbenzenesulfonate, C14H12O4S, 4a, 4‐formylphenyl 4‐chlorobenzenesulfonate, 4b, C13H9ClO4S, and 4‐formylphenyl 4‐bromobenzenesulfonate, C13H9BrO4S, 4c. The title compounds were synthesized under basic conditions from salicylaldehyde/4‐hydroxybenzaldehydes and various aryl sulfonyl chlorides. Remarkably, halogen‐bonding interactions are found to be important to rationalize the solid‐state crystal structures. In particular, the formation of O…X (X = Cl and Br) and type I X…X halogen‐bonding interactions have been analyzed by means of density functional theory (DFT) calculations and characterized using Bader's theory of `atoms in molecules' and molecular electrostatic potential (MEP) surfaces, confirming the relevance and stabilizing nature of these interactions. They have been compared to antiparallel π‐stacking interactions that are formed between the arylsulfonates. [ABSTRACT FROM AUTHOR]

Two novel Cu(ii) complexes, [Cu2L2(μ1.1-N3)2] (1) and [Cu2L2(μ1.1-CH3COO−)2]·2H2O (2), have been synthesized using a tridentate NNO donor Schiff base ligand, 2-[(piperidin-2-ylmethylimino)-methyl]-phenol (HL) and azide or acetate as the co-ligand. Both the structures exhibit elongated (4 + 1) square pyramidal geometries and are centrosymmetric dimers, in which the metal centers are connected by the double μ1.1-azido and acetate bridges. Both complexes exhibit unconventional C–H…π(chelate) interaction along with conventional C–H…π(aryl) supramolecular interactions in the solid-state assembly. A detailed analysis of Hirshfeld surfaces and fingerprint plots elegantly quantifies the interactions within the crystal structures, revealing significant similarities and differences in the interactions experienced by the complexes. The intricate combinations of C–H…π(chelate) and C–H…π(aryl) interactions are fully described along with the computational studies. The binding energies associated with the noncovalent interactions observed in the crystal structures and the interplay between them have been calculated using theoretical DFT calculations. Moreover, the interactions have been characterized by using both Bader's theory of “atoms-in-molecules” and the noncovalent interaction plot (NCI plot). [ABSTRACT FROM AUTHOR]

Four new Pb(ii) complexes of nicotinoylhydrazone and picolinoylhydrazone-based ligands and three different anionic co-ligands (acetate, thiocyanate and iodide) have been synthesized and characterized by structural, analytical and spectroscopic methods. The ligands coordinate to the Pb(ii) metal center in a tridentate fashion via two nitrogen and one oxygen donor atoms either in mono-deprotonated or in neutral forms. Single-crystal X-ray crystallography reveals that the molecular complexes aggregate into larger entities depending upon the anion coordinated to the metal centre. The Pb(ii) center is hemidirectionally coordinated and, consequently, it is sterically ideal for establishing tetrel bonding interactions. Consequently, in the crystal structures of all the complexes, the Pb participates in short contacts with nitrogen, iodide or sulphur atoms. These contacts are shorter than the sums of the van der Waals radii and larger than the sums of the covalent radii, therefore they can be defined as non-covalent tetrel bonding interactions. They interconnect the covalently bonded units (monomers or dimers) into supramolecular assemblies (1D infinite chains and 3D structures). Hirshfeld surface analysis and fingerprint plots have been used to analyse the contribution of contacts involving the Pb atom. We have analysed the interesting supramolecular assemblies observed in the solid state of all four complexes by means of DFT calculations and characterized them using Bader's theory of atoms-in-molecules. [ABSTRACT FROM AUTHOR]

Four hetero-dinuclear nickel(ii)/lead(ii) complexes have been synthesized and characterized. Their structures have been confirmed by single crystal X-ray diffraction studies. In each complex, nickel(ii) is placed in the inner N2O2 compartment and lead(ii) in the outer O2O2′ compartment of the respective Schiff base. In complexes 1, 3 and 4, lead(ii) centres are hemidirectionally coordinated, and thus are well suited for establishing tetrel bonding interactions which have been investigated thoroughly by means of DFT calculations. [ABSTRACT FROM AUTHOR]

A water molecule is encapsulated in a dimeric assembly of a copper(ii) Schiff base complex with a Cu2(NCS)4 moiety. The structure has been confirmed by single crystal X-ray diffraction analysis. Thermogravimetric analysis has been performed to check the stability of the enclathrated water molecule. This theoretical study is devoted to analyzing the stabilization of the H2O molecule in the cavity generated by the formation of the supramolecular dimer of the copper(ii) Schiff base moiety in the solid state. The Cu2(NCS)4 moiety exists as a bimetallic eight-membered ring, which behaves as a π-system establishing C–H…π interactions with two neighbouring copper(ii) Schiff base moieties. The molecular electrostatic potential (MEP) surface of the complex has been computed to rationalize the interaction from an electrostatic point of view. [ABSTRACT FROM AUTHOR]

In recent years, the crystal engineering library has been enriched with a number of previously unrecognized or unnoticed intermolecular interactions, such as agostic, tetrel, chalcogen, pnicogen bonding and chelate ring stacking – collectively referred to as “unconventional interactions”. Many open questions remain unaddressed regarding their ability to form synthon interactions, specificity, and cooperativity, for example with π–π stacking interactions. In this work, we throw light on the formation of chelate ring stacking in metal–organic assemblies of nicotinohydrazide ligands (N′-(1-(2-pyridyl)ethylidene)nicotinohydrazide (HL) and N′-(phenyl(pyridin-2-yl)methylene)nicotinohydrazide (HL1)) with mercury(ii) halide (HgBr2, HgI2) salts. Their reaction produced five compounds, namely [Hg(μ-L)BrHgBr2]n (1), [Hg(μ-L1)Br]n (2), [Hg(L)I2] (3), [Hg(HL1)I2]·(CH3OH) (4), and [Hg(μ-L1)I]n (5). Crystal structure analysis reveals that chelate ring stackings are formed in four of the reported metal–organic compounds, and are common also in the literature precedents. The energies of chelate ring stackings and π–π heterocycle stackings have been computed and analyzed by means of DFT calculations, and the results were verified using Bader's theory of “atoms in molecules”. These results provide a rationale for preferential formation of both unconventional and conventional stackings and allow us to conclude that chelate ring interaction may be considered as a synthon interaction for nicotinohydrazide metal complexes. Interpretations for packing differences imposed by the substituent effect (substitution of methyl group in HL for phenyl group in HL1) were provided based on the Hirshfeld surface analysis and 2D fingerprint plots of the crystal structures reported here. [ABSTRACT FROM AUTHOR]

Two new Co(II) and Cu(II) coordination polymers, {Co(HL1)2(μ-L2)(H2O)2}n (1) and {[Cu(HL1)2(μ-L2)H2O]·H2O}n (2) (H2L1 = Phthalic acid and L2 = 2-aminopyrazine), have been synthesized by slow evaporation of solvent and characterized by IR spectroscopic, elemental, single-crystal X-ray diffraction and thermal analysis. X-ray results indicate that in both the polymers, phthalate acts as a monodentate ligand and the aminopyrazine ligand is responsible for the formation of the infinite one-dimensional chain structure. The solid-state structures are stabilized through hydrogen bonds and N-H···π interactions by generating two-dimensional layered structures. Finally, the non-covalent interactions have been studied energetically and using Bader's theory of atoms in molecules by means of Density Functional Theory (DFT) calculations. The influence of the metal coordination on the strength of the interaction has been studied using molecular electrostatic potential surface calculations. [ABSTRACT FROM AUTHOR]

Three heteronuclear cobalt(iii)/sodium Schiff base complexes have been synthesized and characterized by elemental and spectral analysis. The structures of all three complexes have been confirmed by single crystal X-ray analyses. Each of these three complexes crystallizes in monoclinic space group P21/c. In each complex, cobalt(iii) is placed in the inner N2O2 compartment and sodium is placed in the outer O2O′2 compartment (O and O′ denote the phenolic and ethoxy/methoxy oxygen atoms, respectively) of the Schiff bases. With decrease in steric hindrance around the O2O′2 compartment by the replacement of ethyl groups with methyl groups, tetranuclear complexes resulted instead of dinuclear ones. Interesting carbon bonding interactions in the solid state of the complexes have been studied by means of DFT calculations using several computational tools such as “atoms-in-molecules” (AIM) and natural bond orbital (NBO) analyses. [ABSTRACT FROM AUTHOR]

Variable temperature magnetic measurements of a novel tetranuclear nickel(ii) complex, consisting of two pseudo-dinuclear entities bridged by an end-to-end azide, indicate the presence of both intra- and inter-dinuclear ferromagnetic interactions (J1 = 16.48 cm−1 and J2 = 24.17 cm−1, respectively), as also corroborated by DFT calculations (J1 = 12.0 cm−1 and J2 = 29.2 cm−1). [ABSTRACT FROM AUTHOR]

Abstract: Two new hetero‐dinuclear nickel(II)/cadmium(II) complexes, [(DMF)1.78(DMSO)0.22NiL1Cd(Cl)(NCS)] (1) and [(DMF)(H2O)NiL2CdCl2]⋅DMF (2) with compartmental Schiff bases, H2L1=N,N′‐bis(3‐ethoxysalicylidene)‐2,2‐dimethylpropane‐1,3‐diamine and H2L2 = N,N′‐bis(5‐bromo‐3‐methoxysalicylidene)‐2,2‐dimethylpropane‐1,3‐diamine, have been prepared and characterized by single crystal X‐ray diffraction analysis. In each complex, nickel(II) and cadmium(II) are placed in the N2O2 and O2O2' compartments of the Schiff base respectively. Both complexes form interesting supramolecular assemblies in the solid state. Energy associated with conventional C−H⋅⋅⋅π interaction in complex 1 and unconventional σ‐hole carbon bonding interaction in complex 2 in the solid state of these complexes are estimated by DFT calculation and characterized by Natural Bond Orbital analysis and molecular electrostatic potential surface analysis as well. [ABSTRACT FROM AUTHOR]

The present report describes the synthesis and structural characterizations of six new manganese(III) complexes with redox-active tetrachlorocatecholate ligand in the presence of different ancillary ligands (pyridines and imidazole). X-ray crystal structure analysis reveals that the geometry of manganese(III) centres in 1 and 2 is essentially square pyramidal, while it is discrete octahedron in compounds 3 – 6 . These preferential structural diversities in these systems have been critically analysed by theoretical calculations. Remarkably, the characterization of both π ⋯ π stacking interactions and Mn Mn bonds in the supramolecular dimeric aggregates in the solid state in 1 and 2 by means of the Bader's theory of “atoms in molecules” (AIM) is quite interesting as that nicely corroborates the experimental fact. All the complexes are active toward the phenoxazinone synthase like activity and the detailed kinetic analysis was performed to get better insight into their catalytic efficiency. Electrochemical property of these complexes as well as different donor property of the ancillary ligands clearly establish that the ease of reduction of the metal centre i.e., the catalytic ability is favoured when the metal centre is bonded to the electron deficient pyridyl systems. EPR spectroscopy and theoretical study are further helpful to get insight into origin of the catalytic activity in these compounds. The present report overall highlights that tuning of the geometry and catalytic activity of manganese(III) complexes with tetrachlorocatecholate ligand can be attained by the introduction of different substitutions in ancillary pyridine ligands. [ABSTRACT FROM AUTHOR]

A novel mononuclear Mn(iii) complex, [MnIII(L1)Cl(H2O)]·H2O (1), and a tetranuclear Zn(ii)–Mn(ii) complex, [{ZnII2(L2)2Cl2}MnII2(μ1,1-N3)2(H2O)2]·2H2O (2), have been synthesized involving azo Schiff base ligands, viz. H2L1 = (E)-6,6′-((1E,1′E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2-methoxy-4-((E)-p-tolyldiazenyl)phenol) and H2L2 = (E)-6,6′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))bis(2-methoxy-4-((E)-p-tolyldiazenyl)phenol), respectively. The solid-state structures were determined by single crystal X-ray crystallography. In complex 1, the Mn(iii) centre adopts slightly distorted octahedral geometry, while in complex 2 the Mn(ii) centre residing in the outer core of the ligand adopts a distorted pentagonal bipyramidal geometry. In complex 1, the chloride ion simply acts as a terminal coligand, while in complex 2, azide ions bind the metal centres in an end-on bridging fashion to produce a tetranuclear complex. The phenoxazinone synthase-like activity of both complexes has been examined and a detailed investigation of the structure–property correlation has been performed. Whereas the mononuclear complex 1 exhibits significant phenoxazinone activity, complex 2 is almost inactive, although in both complexes labile sites are available at manganese centres for substrate binding. The present work therefore highlights the importance of higher oxidation states of manganese over nuclearity for the development of better in vitro catalysts. In addition, extensive efforts have been made to visualize and quantify all supramolecular interactions present in 1 and 2. [ABSTRACT FROM AUTHOR]

Herein we report the first X-ray solid state characterization of a Ag(i) complex with cytidine-5′-monophosphate (HCMP) of the formula Ag(HCMP)·H2O. The coordination of Ag(i) to HCMP is via both the N3 and O2 atoms of two cytosine moieties and the phosphate group. The short Ag(i)–Ag(i) distances (2.99 Å) suggest an interesting argentophilic attraction as a stabilization source of the final solid state structure along with ancillary O…Ag, H-bonding and π…π interactions that have been rationalized using DFT calculations. [ABSTRACT FROM AUTHOR]

Two structurally similar mononuclear vanadium(V) complexes, [VO 2 (L 1 )] ( 1 ) and [VO 2 (L 2 )] ( 2 ) [where HL 1 = 1-(2-(dimethylamino)ethyliminomethyl)naphthalen-2-ol and HL 2 = 1-(2-(diethylamino)ethyliminomethyl)naphthalen-2-ol] have been synthesized and characterized by elemental and spectral analysis. Structures of both complexes have been confirmed by single crystal X-ray diffraction studies. Weak non-covalent interactions lead to the formation of extended supramolecular assemblies in them. The crystal packing in complex 2 is different compared to that in complex 1 due to the presence of ethyl groups instead of methyl groups bonded to the nitrogen atoms in the ligand moieties. The importance of non-covalent C H⋯π, π⋯π (chelate ring) and hydrogen bonding interactions in the solid state of both complexes has been described by means of DFT and MEP calculations and characterized using Bader’s theory of “atoms in molecules” (AIM). Particular attention has been paid to those interactions involving the chelate ring that are referred as uncommon interactions in this manuscript. [ABSTRACT FROM AUTHOR]

Two new 3-aryl-5-(4-nitrobenzylidene)-2-thioxothiazolidin-4-one derivatives ( 1 & 2 ) were synthesized by the Knoevenagel condensation reaction of 3-(4-aryl)-2-thioxo-1,3-thiazolidin-4-ones with 4-nitrobenzaldehyde. Both products were isolated as orange crystalline solids in good yields and were fully characterized by analytical, spectroscopic and structural methods. The interesting supramolecular assemblies of the title compounds observed in the solid state were analyzed by Density Functional Theory (DFT) calculations (M06-2X/def2-TZVP), Molecular Electrostatic Potential (MEP) surfaces and characterized by means of the Bader's theory of “atoms-in-molecules” (AIM) and NCIplot. The computation of the energy features of the diverse noncovalent interactions including C H⋯π, π⋯π and lp⋯π-hole interactions revealed their conspicuous role in the stabilization of the three-dimensional supramolecular frameworks for both compounds in addition to the C H⋯O/S H-bonding interactions. [ABSTRACT FROM AUTHOR]

Three metallamacrocycles and one coordination polymer were obtained by using coordination driven self-assembly of the HgI2 salt with four different ligands: 2,2′-butan-1,4-diylbis(oxy)dianiline (L1), 1,4-bis(2′-formylphenyl)-1,4-dioxabutane bis(isonicotinoylhydrazone) (L2), (E)-N′-(pyridin-3-ylmethylene)isonicotinohydrazide (L3) and (E)-1-(pyridin-3-yl)-N-(pyridin-3-ylmethyl)methanimine (L4). The coordination compounds were studied by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction analyses. Reaction of the HgI2 salt with L1, L2 and L3 yields metallamacrocycles of formula [(HgI2)2(μ-L1)2] (1), [(HgI2)2(μ-L2)2] (2), [HgI2(μ-L3)]4 (3). In contrast, the reaction with L4 under the same conditions yields a coordination polymer of formula [{HgI2(L4)}]n (4). In addition, the X-ray structure of L2 is also reported. The influence of the flexibility of the ligand on the final shape and nuclearity of the macrocycle is also analysed. Hirshfeld surface analysis and fingerprint plots facilitate a comparison of intermolecular interactions in all compounds, which are crucial in the construction of the supramolecular architectures. Finally, some noncovalent interactions have been evaluated energetically using DFT calculations and characterized using Bader's theory of atoms-in-molecules. [ABSTRACT FROM AUTHOR]

Tri(phosphonio)methanide dication 32+, prepared from a trifluoromethylsulfanylphosphonium dication ( 12+) via an intramolecular electrophilic aromatic substitution reaction, is an unexpected P-based, water-resistant Lewis acid that is capable to selectively and reversibly bind fluoride ions from organic/aqueous biphasic solution. The formed complex is an unusual fluorophosphorane ( [3-F]OTf). The multiple donor-acceptor interactions of 32+ that are crucial for the fluoride fixation have been elucidated by quantum chemical calculation. Compound [3-F]OTf can also be used as a convenient anhydrous fluoride ion source and was probed as a suitable catalyst of the silylotrifluoromethylation of various aldehydes. [ABSTRACT FROM AUTHOR]

Tri(phosphonio)methanide dication 32+, prepared from a trifluoromethylsulfanylphosphonium dication ( 12+) via an intramolecular electrophilic aromatic substitution reaction, is an unexpected P-based, water-resistant Lewis acid that is capable to selectively and reversibly bind fluoride ions from organic/aqueous biphasic solution. The formed complex is an unusual fluorophosphorane ( [3-F]OTf). The multiple donor-acceptor interactions of 32+ that are crucial for the fluoride fixation have been elucidated by quantum chemical calculation. Compound [3-F]OTf can also be used as a convenient anhydrous fluoride ion source and was probed as a suitable catalyst of the silylotrifluoromethylation of various aldehydes. [ABSTRACT FROM AUTHOR]

The polarized, cationic diphosphene [(ClImDipp)P=P(Dipp)]+ as the triflate salt 7[OTf](ClImDipp=4,5-dichloro-1,3-bis(Dipp)-imidazol-2-yl; Dipp=2,6-diisopropylphenyl) reacts with azides of type RN3 (R=Dipp or Dmp; Dmp=2,5-dimethylphenyl) in a [2+3] cycloaddition reaction followed by the release of N2 and a subsequent electrocyclic ring-closing reaction to azadiphosphiridine salts [(ClImDipp)P-P(Dipp)-N(R)] 10a,b[OTf] (R=Dipp or Dmp). The reaction of 7[X] (X=OTf, GaCl4) with the electron-rich azides Me3SiN3 and NaN3 give the unusual diphosphenimine derivatives [(ClImDipp)P−P(Dipp)=N(SiMe3)]+ ( 11[OTf]) and [(ClImDipp)P−P(Dipp)=N(GaCl3)] ( 12), respectively, featuring an acyclic P2N moiety. Theoretical calculations provide insights into the reaction mechanisms to the cyclic and acyclic forms, in which the thermodynamic stability of the latter prevents the electrocyclic ring closure. [ABSTRACT FROM AUTHOR]

The polarized, cationic diphosphene [(ClImDipp)P=P(Dipp)]+ as the triflate salt 7[OTf](ClImDipp=4,5-dichloro-1,3-bis(Dipp)-imidazol-2-yl; Dipp=2,6-diisopropylphenyl) reacts with azides of type RN3 (R=Dipp or Dmp; Dmp=2,5-dimethylphenyl) in a [2+3] cycloaddition reaction followed by the release of N2 and a subsequent electrocyclic ring-closing reaction to azadiphosphiridine salts [(ClImDipp)P-P(Dipp)-N(R)] 10a,b[OTf] (R=Dipp or Dmp). The reaction of 7[X] (X=OTf, GaCl4) with the electron-rich azides Me3SiN3 and NaN3 give the unusual diphosphenimine derivatives [(ClImDipp)P−P(Dipp)=N(SiMe3)]+ ( 11[OTf]) and [(ClImDipp)P−P(Dipp)=N(GaCl3)] ( 12), respectively, featuring an acyclic P2N moiety. Theoretical calculations provide insights into the reaction mechanisms to the cyclic and acyclic forms, in which the thermodynamic stability of the latter prevents the electrocyclic ring closure. [ABSTRACT FROM AUTHOR]

Reaction of tetrameric trimethylplatinum(iv) iodide with an excess of 3-substituted pyridines in chloroform afforded mononuclear complexes, [PtMe3L2I] (L = 3-CNpy, 3-Brpy, 3-MeOpy, 3-Mepy and 3-Etpy). The complexes were characterized by 1H NMR, CHN analysis and X-ray single crystal structure analysis. The mononuclear complexes undergo reaction with trimethylplatinum(iv) iodide in chloroform to form the corresponding dinuclear forms (both syn and anti). A comparison of both the mononuclear and dinuclear forms in solution for a particular pyridine substituent has been studied in detail with the help of 1H NMR spectroscopy, ably supported by DFT computational studies. The investigation further shows the influence of the pyridine substituent on controlling the mode of the reaction. The crystal structures of two dinuclear complexes, syn-[PtMe3(3-CNpy)I]2 and anti-[PtMe3(3-Brpy)I]2, have also been described here. [ABSTRACT FROM AUTHOR]

Three new heteronuclear nickel(ii)/cadmium(ii) complexes, [(SCN)(Cl)Cd(L)Ni(DMF)2] (1), [(SCN)(CH3CO2)Cd(L)Ni(CH3OH)2] (2) and [(SCN)(Cl)Cd(L)Ni(NH2CH2CH2CH2NH2)]n (3) {where H2L = N,N′-bis(3-ethoxy-salicylidene)propane-1,3-diamine is a N2O4 compartmental Schiff base}, have been synthesized and characterized. The structures of the complexes have been confirmed by single crystal X-ray diffraction studies. In each complex, nickel(ii) is placed in the inner N2O2 environment and cadmium(ii) is placed in the outer O4 compartment of the compartmental Schiff base. Furthermore, the importance of unconventional C–H…π (chelate) interactions in the solid state of both complexes and C–H…π (thiocyanate) interaction in complex 2 has been described by means of DFT and MEP calculations and characterized using NCI plots. All complexes show photoluminescence at room temperature upon irradiation by ultraviolet light. The lifetimes of excited states are in the range of 2–6 ns. [ABSTRACT FROM AUTHOR]

This paper reports the syntheses and structural characterization of three new Cu(II) coordination polymers, namely [Cu(BAEE)(N 3 ) 2 ] ∝ ( 1 ), [Cu(BAEE)(NCO) 2 ] ∝ ( 2 ) and [Cu(BAEE)(NCS) 2 ] ∝ ( 3 ), where BAEE is 1,2-bis(2-aminoethoxy)ethane. Compound 1 is a one-dimensional (1D) single-stranded normal helical structure, while compounds 2 and 3 are extraordinary single-stranded meso-helical polymers. The influence of pseudohalides in these systems is observed as the azide ions are cis coordinated in 1 and the thiocyanate ions are trans coordinated in 3 , while alternate metal centers are either cis or trans coordinated with cyanate ions in 2 . These geometrical preferences play a crucial role in the diverse helicity in these chain structures, where the cis arrangement (in 1 ) favors a uniform helicity in the structure and the trans arrangement (in 2 and 3 ) of the pseudohalide ligands around the copper(II) center brings meso-helicity in the chains. The energetic difference of the cis / trans isomers and the formation energies of the different assemblies using DFT calculations suggest that the different H-bond acceptor ability of the thiocyanate ion determines the different architecture observed in 3 . Our results highlight how the geometrical preferences of the pseudohalides around the copper(II) center influence the helical diversity in these systems and thereby provide a clue toward the development of uncommon coordination polymers with amazing meso-helical character. [ABSTRACT FROM AUTHOR]

The synthesis of a metalled double-helix containing exclusively silver-mediated C*−C* base pairs is reported herein (C*=N1hexylcytosine). Remarkably, it is the first crystal structure containing infinite and consecutive C*-AgI-C* base pairs that form a double helix. The AgI ion occupies the center between two C* residues with N(3)−Ag bond lengths of 2.1 Å and short AgI−AgI distances (3.1 Å) suggesting an interesting argentophilic attraction as a stabilization source of the helical disposition. The solid-state structure is further stabilized by metal-mediated base-pairs, hydrogen bonding and π-stacking interactions. Moreover, the angle N(3)−Ag-N(3) is almost linear in the [Ag(N1hexylcytosine)2]+ motif and the bases are not coplanar, thus generating a double-strand helical aggregate in the solid state. The noncovalent and argentophilic interactions have been rationalized based on DFT calculations. [ABSTRACT FROM AUTHOR]

A one-dimensional polynuclear end-on azide bridged octahedral cadmium(II) Schiff base complex, [{CdL(μ-1,1-N 3 )} 2 Cd(μ-1,1-N 3 ) 2 ·1.76CH 3 OH] n {HL = 2-(3-(dimethylamino)propyliminomethyl)-6-ethoxyphenol} has been synthesized and characterized by single crystal X-ray crystallography. The complex crystallizes in monoclinic space group C 2/ c with cell dimensions, a = 21.4706(8) Å, b = 9.9542(4) Å, c = 19.3257(7) Å, β = 103.7819(11)°. Extended supra-molecular assemblies were generated through weak non-covalent interactions. The energetic features of these interactions have also been studied by means of DFT calculations. The complex exhibits good photoluminescence in DMSO medium. The application of the complex as a photocatalyst for the decomposition of organic dye in visible light has been explored. [ABSTRACT FROM AUTHOR]

A square planar copper(II) complex has been synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction study. The X-ray structure of the complex is used to analyze the crucial role of the π-interactions in the solid state. The complex also shows significant hydrogen-bonding interactions. Moreover, we have evaluated energetically both interactions by means of high level DFT calculations (BP86-D3/def2-TZVP) and characterized them using the Bader's theory of “atoms-in-molecules”. [ABSTRACT FROM AUTHOR]

Three new copper(II) complexes, [Cu 2 L 2 Cl 2 (4,4′-bpy)]·2.7H 2 O ( 1 ), [CuL(4,4′-bpy)(H 2 O)]NO 3 ( 2 ) and [CuL(4,4′-bpy)(H 2 O)]ClO 4 ( 3 ), where HL = 1-[1-(2-Dimethylamino-ethylimino)-ethyl]-naphthalen-2-ol, have been synthesized and characterized by elemental analysis, IR, UV–Vis spectroscopy and single crystal X-ray diffraction studies. Complex 1 is a centrosymmetric dinuclear species in which 4,4′-bipyridine acts as bridging bidentate linker between the two copper(II) ions whereas, complexes 2 – 3 are rare mononuclear complexes in which the 4,4′-bpy ligand shows monodentate coordination mode stabilized by H-bonding interactions through its electronegative non-coordinated N-atom. These interactions involve imine and methylene hydrogen atoms of the Schiff-base ligand for 2 , whereas a single H-bond with one of the hydrogen atoms of the coordinated water is established in 3 . In addition, several non-covalent interactions like hydrogen bonding and π-based interactions (C–H/π, anion–π and π–π stacking) are also observed in crystal packing of all three complexes. These interactions have been investigated by means of DFT calculations and assigned with discrete interaction energies. The strong influence of the coordination of the 4,4′-bpy ligand to the copper(II) centers upon the binding strength of the π-based interactions has also been demonstrated. [ABSTRACT FROM AUTHOR]

Three new trinuclear hetero-metallic complexes [(CuL)2Zn(NCS)2] (1), [(CuLR)2Zn(NCS)(μ1,1-NCS)] (2) and [(CuLR)2Cd(μ1,3-NCS)2] (4) have been synthesized using [CuL] and [CuLR] as “metalloligands” (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine and H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine). All three complexes are characterized by elemental analysis, spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar “metalloligands” [CuL] are coordinated to a central Zn(ii) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal isothiocyanate ions as is usually found in such complexes. In contrast, in complex 2, the two terminal “metalloligands” [CuLR] are square pyramidal, as one of the SCN− ions makes an unusual μ1,1-NCS bridge between copper centers while the other one coordinates to Zn(ii) through a N atom in a usual fashion making its geometry also square pyramidal. For 4 which possesses an angular trinuclear structure, in addition to double phenoxido bridges from two terminal [CuLR], both the SCN− ions are S-bonded to Cd(ii) and form a bridge (cis-μ1,3-SCN) between Cd(ii) and each of the terminal Cu(ii) ions. This structure is different from its unreduced analogue in which NCS− was N-terminal coordinated to Cd(ii) (3/3′). All the structures have been optimized using density functional theory (DFT) calculations. It has been found that for H2L, optimized structures like 1 and 2 differ only by 0.4 kcal mol−1 but the H2LR structure 2 is more stable by 5.5 kcal mol−1 than the structure resembling 1. For Cd(ii) complexes also, H2L optimized structures such as 3 and 4 do not differ significantly in energy (1.0 kcal mol−1) but the H2LR structure 4 is more stable than that of 3 by 4.6 kcal mol−1. In fact, structure 4 has been found to be the most stable one among the other possible isomers of H2LR. [ABSTRACT FROM AUTHOR]

A new chloride-dimethylsulfoxide-iridium(III) complex with histaminium(1+) trans -[Ir III Cl 4 (DMSO-κS)(Histamine-H)]·2H 2 O ( 1 ) and a precursor mer -[Ir III Cl 3 (DMSO-κO)(DMSO-κS) 2 ] ( 2 ) have been synthesized and characterized by spectroscopic techniques and by single crystal X-ray diffraction studies. The nature of an interesting lp−π/π−π/π−lp assembly found in compound 1 has been deeply studied by means of DFT calculations and several computational tools as NCI (Non-Covalent Interaction) plot and Bader’s theory of “atoms in molecules”. [ABSTRACT FROM AUTHOR]

Three solid materials, [Pb( HL)(SCN)2] ⋅CH3OH ( 1), [Pb( HL)(SCN)2] ( 2), and [Pb( L)(SCN)] n ( 3), were obtained from Pb(SCN)2 and an unsymmetrical bis-pyridyl hydrazone ligand that can act both as a bridging and as a chelating ligand. In all three the lead center is hemidirectionally coordinated and is thus sterically optimal for participation in tetrel bonding. In the crystal structures of all three compounds, the lead atoms participate in short contacts with thiocyanate sulfur or nitrogen atoms. These contacts are shorter than the sums of the van der Waals radii (3.04-3.47 Å for Pb ⋅⋅⋅S and 3.54 Å for Pb ⋅⋅⋅N) and interconnect the covalently bonded units (monomers, dimers, and 2D polymers) into supramolecular assemblies (chains and 3D structures). DFT calculations showed these contacts to be tetrel bonds of considerable energy (6.5-10.5 kcal mol−1 for Pb ⋅⋅⋅S and 16.5 kcal mol−1 for Pb ⋅⋅⋅N). A survey of structures in the CSD showed that similar contacts often appear in crystals of PbII complexes with regular geometries, which leads to the conclusion that tetrel bonding plays a significant role in the supramolecular chemistry of PbII. [ABSTRACT FROM AUTHOR]

Herein we report the use of polyether binders as regulation agents (RAs) to enhance the enantioselectivity of rhodium-catalyzed transformations. For reactions of diverse substrates mediated by rhodium complexes of the α,ω-bisphosphite-polyether ligands 1- 5, a- d, the enantiomeric excess ( ee) of hydroformylations was increased by up to 82 % (substrate: vinyl benzoate, 96 % ee), and the ee value of hydrogenations was increased by up to 5 % (substrate: N-(1-(naphthalene-1-yl)vinyl)acetamide, 78 % ee). The ligand design enabled the regulation of enantioselectivity by generation of an array of catalysts that simultaneously preserve the advantages of a privileged structure in asymmetric catalysis and offer geometrically close catalytic sites. The highest enantioselectivities in the hydroformylation of vinyl acetate with ligand 4 b were achieved by using the Rb[B(3,5-(CF3)2C6H3)4] (RbBArF) as the RA. The enantioselective hydrogenation of the substrates 10 required the rhodium catalysts derived from bisphosphites 3 a or 4 a, either alone or in combination with different RAs (sodium, cesium, or ( R, R)-bis(1-phenylethyl)ammonium salts). This design approach was supported by results from computational studies. [ABSTRACT FROM AUTHOR]

This study reports the synthesis of a new catenane Gd(III) complex using pyridine-2,6-dicarboxylic acid (H 2 pydc) as ligand. The structure of [Gd(pydc)(Hpydc)(H 2 O) 2 ] n ( 1 ) was characterized by IR spectroscopy, X-ray diffraction methods and the elemental analysis to check the purity of the compound. On the basis of crystallographic data, compound 1 contains a Gd(III) metal center that is coordinated to seven oxygen atoms of two tridentate and one monodentate H 2 pydc ligands and two coordinated water molecules. Other lanthanoid complexes involving this ligand are available in the literature; however, this is the first example where a combination of monoanionic (Hpydc − ) and dianionic (pydc 2 − ) forms of the ligand counterbalance the Gd 3 + metal center. The intermolecular interactions in this novel system consist of different kinds of H-bonding and π-stacking interactions in addition to antiparallel CO ⋯ CO interactions which have been analyzed using DFT calculations and the Bader's theory of “atoms in molecules”. [ABSTRACT FROM AUTHOR]

A new solvated complex of the uranyl ion, [UO 2 (quin) 2 (H’quin)]·DMF ( 1 ), (Hquin = 8-hydroxyquinoline and H’quin = quinolinium-8-olate, i.e. the zwitterionic form of H quin ) was synthesized and investigated by means of elemental analysis, IR spectroscopy and X-ray crystallography. Interestingly one coordinated 8-hydroxyquinoline is protonated, thus provoking the simultaneous existence of an electron rich and electron poor ring in the same molecule. This clearly enhances the ability of this ring to form antiparallel stacking interactions that are responsible for the solid state architecture of compound 1 . This aspect has been analyzed by means of density functional theory calculations (DFT), molecular electrostatic potential (MEP) tool and Bader’s theory of “atoms in molecules”. [ABSTRACT FROM AUTHOR]

This paper describes the one-potsynthesis of two CuBr based coordinationpolymers, {[Cu(μ2-L1)Br]·1.87H2O}n(1) and {[Cu(μ2-L2)Br]·C4H10O}n(2), where L1=2,3-dihydro-5,6-bis(4-methoxyphenyl)pyrazine and L2= 5,6-diphenyl-2,3-dihydropyrazine,upon reduction of copper(II) at ambient conditions. The structureshave been confirmed by single crystal X-ray diffraction analysis.Both complexes are found to be highly inert toward oxidation. Finally,a density functional theory (DFT) study of the energetic featuresof several noncovalent interactions observed in the solid state hasbeen analyzed and characterized using Bader’s theory of “atomsin molecules” and the cuprophilic interactions in complex 2using natural bond orbital methodology. [ABSTRACT FROM AUTHOR]

The direct reaction between p -chlorobenzoic acid and metal nitrate salts resulted in the formation of a novel heterometallic μ 3 -oxo trinuclear cluster with the formula [Cr III 2 Mn II O(C 7 H 4 O 2 Cl) 6 (Py) 3 ]C 7 H 5 O 2 Cl ( 1 ), which has been characterized by elemental analysis, electronic and IR spectra, and single-crystal X-ray crystallography. The electronic spectrum of the complex exhibited two spin-allowed bands for Cr III in the regions 17 900 and 22 750 cm −1 , which could be assigned to the transitions from 4 A 2 g (F) to 4 T 2 g (F) and 4 T 1 g (F) , respectively. We have also examined the Cambridge Structural Database to investigate the abundance of this type of complex in terms of the trivalent/divalent metal ions and the hetero/homometallic nature of the trinuclear cluster. We have studied the relative stability of the different cluster situations, calculating the energetic costs of a series of metal substitution reactions by means of high level DFT calculations. Moreover, we have analyzed the effect of the p -chlorine substituent in benzoic acid, since the formation of halogen bonding interactions in the solid state are important in determining the crystal packing of 1. [ABSTRACT FROM AUTHOR]

Three Cu and one Co complexes of three pyridine-2,6-dicarboxylic acid derivatives were synthesized by proton transfer reactions. They are formulated as {Cu[(ampym)(hypyafc)(H2O)]}⋅H2O (1), {[Co(pyzdc)(H2O)2]⋅H2O}n (2), [Cu(d/p/c)(µ-dipic)Cu(ii)(H2O)5]⋅2H2O (3) and [Cu3(dipic)4(en)2]⋅enH2⋅4H2O (4) where ampym = 2-amino-4-methylpyrimidine, hypydc-4-hydroxypyridine-2,6-dicarboxylic acid, pyzdc = pyrazine-2,3-dicarboxylic acid, dipic = pyridine-2,6-dicarboxylic acid, en = ethylenediamine. The complexes have been characterized by single crystal X-ray diffraction. Complex 1 is five-coordinated with a distorted square pyramidal geometry around Cu(II) where hypydc acts as a tridentate ligand, ampym as a monodentate ligand and one water molecule coordinated in the axial position. Complex 2 is a linear polymer containing a six-coordinated Co(II) metal center, which is surrounded by N and O atoms from two pyzdc ligands and two coordinated water molecules. Complex 3 is a binuclear compound containing two six-coordinated Cu(II) ions, one coordinated to two dipic ligands while the other one is coordinated by five water molecules and one oxygen atom belonging to the bridging carboxylate group. Complex 4 is a trinuclear complex where two identical ions are hexa-coordinated to four carboxylate groups belonging to two dipic ligands and central ion is coordinated to two ethylenediamine ligands and two oxygen atoms of the dipic ligands. The non-covalent interactions that play important roles in the stabilization of the crystal structures have been analysed for several compounds by means of Density Functional Theory (DFT) calculations and characterized using the Bader's theory of "atoms in molecules" (AIM). The evaluation of the binding energies associated to each noncovalent interaction is useful for rationalizing their influence in the crystal packing. The formation of an unprecedented lp-π-hole interaction in 1 is remarkable. [ABSTRACT FROM AUTHOR]

Two new trinuclear hetero-metallic copper(II)-cadmium(II) complexes [(CuL)2Cd(NCS)2] (1) and [(CuLR)2Cd(SCN)2] (2) have been synthesized using [CuL] and [CuLR] as ''metalloligands'' (where H2L = N,N'-bis(salicylidene)-1,4-butanediamine and H2LR = N,N'-bis(2-hydroxybenzyl)-1,4-butanediamine) respectively. Both the complexes were characterized by elemental analysis, various spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar ''metalloligands'' [CuL] are coordinated to a central Cd(II) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal thiocyanate ions. In complex 2, which is linear, in addition to the double phenoxido bridge, two SCN- coordinate to the trans positions of the central octahedral Cd(II) via S atoms. Theoretical calculations on the energetic difference between the two possible coordination modes of the thiocyanate anion to the Cd atom reveal that N-coordination is preferred over S-coordination in agreement with the much greater abundance of the reported N-bonded structures. In 2, there is a strong N-H . . . NCS-Cd H-bonding interaction, the binding energy of which is computed to be approximately -9.3 kcal mol-1, which is sufficient to compensate the 9.0 kcal mol-1 of energetic cost due to the unusual Cd-SCN coordination mode. [ABSTRACT FROM AUTHOR]

Two dinuclear [Ni2L2(o-(NO2)C6H4COO)2(H2O)] (1), [Ni2L2(p-(NO2)C6H4COO)2(H2O)]·0.5CH3OH (2) complexes and one trinuclear [Ni3L2(p-(NO2)C6H4COO)4]·C2H5OH (3) Ni(II) complex have been synthesized using a tridentate Schiff base ligand, 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) along with ortho- and para-nitro benzoate as co-ligands. All these three (1–3) complexes have been characterized by spectral analysis, X-ray crystallography and variable temperature magnetic susceptibility measurements. The structural analyses reveal that complexes 1 and 2 are dinuclear in which two μ2-phenoxido and a water molecule bridge the two Ni(II) centers to make the complexes face sharing bioctahedra. Complex 3 is a linear triple bridged (phenoxido and carboxylato) trinuclear Ni(II) complex. Variable-temperature magnetic susceptibility studies indicate the presence of ferromagnetic exchange coupling in complexes 1–3 with J values of 25.4, 28.1 and 6.2 cm–1 respectively. Theoretically obtained J values of 21.4 cm–1 (for 1), 22.0 cm–1 (for 2) and 9.3 cm–1 (for 3) corroborate very well the experimental results. DFT calculation also shows that stronger H-bonding interactions present in the case of carboxylate based coligands stabilise the triple oxido-bridged complexes. [ABSTRACT FROM AUTHOR]

New chlorido-dimethylsulfoxide-iridium(III), ruthenium(III) and rhodium(III) complexes with the 2-(1Hpyrazol- 1-yl)-pyrimidine (pyrapyr) ligand (OC-6-N1)-[RhIIICl3(DMSO-κS)(pyrapyr)] (1a, N = 3 and 1b, N = 4); (OC-6-N1)-[RuIIICl3(DMSO-κS)(pyrapyr)] (2a, N = 3 and 2b, N = 4) and (OC-6-N1)-[IrIIICl3(DMSO-κS)- (pyrapyr)] (3a, N = 3 and 3b, N = 4) have been synthesized and characterized by spectroscopic techniques and by single crystal X-ray diffraction studies (1a, 1b, 2a, 2b, a disordered crystal 3a/3b and a cocrystal 3a·3b). In all cases, the metal centers show octahedral geometry coordinated to three chloride ligands and one S coordinated dimethylsulfoxide (DMSO-κS). The coordination sphere of the metal is completed by the pyrapyr molecule. Two different coordination modes are observed: (i) the DMSO-κS is opposite to the pyrimidinic N atom (IUPAC nomenclature is OC-6-31 denoted herein as trans); (ii) DMSO-κS is opposite to the pyrazolic N atom (IUPAC nomenclature is OC-6-41 denoted as cis). For Rh(III) the kinetic product (cis) yields the thermodynamic (trans) upon heating a solution of the kinetic product and both isomers have been X-ray characterized. Conversely for Ru(III), both kinetic and thermodynamic complexes have been obtained by using different procedures. Both isomers have been characterized by X-ray crystallography and the kinetic product does not yield the thermodynamic upon heating a solution of the former. Furthermore, the Ir(III) behaves differently, since both isomers are energetically equivalent and both isomers co-crystallize in the solid state. The kinetic/thermodynamic mechanism that yields the different isomers has been studied by using theoretical DFT calculations for each metal. Finally, two Ru(II) complexes (OC-6-N1)-[RuIICl2(DMSO-κS)2(pyrapyr)] (4a, N = 3 and 4b, N = 4) are also described and X-ray characterized. They were obtained as minor products during the synthesis of 2a. [ABSTRACT FROM AUTHOR]

A new dinuclear di(μ-alkoxido) bridged complex [Fe2L2] (1) (H3L = N,N′-bis{1-(2-hydroxyphenyl)-ethylidene}-2-hydroxy-1,3-propanediamine) has been synthesized and characterized. The structure of 1 consists of a centrosymmetric dimer where two crystallographically equivalent metal ions are asymmetrically bridged by two alkoxido oxygen atoms. In the structure, each ligand coordinates to one Fe(iii) centre and consequently the imino nitrogen atoms are in cis positions, which is rather unusual for this ligand. Variable-temperature magnetic susceptibility measurements of the complex indicate that the two iron(iii) centres are antiferromagnetically coupled (J = −17.46 cm−1). The exchange mechanism has been investigated by means of DFT calculations. In addition, the theoretical study has been also used to rationalize the unusual coordination mode of the Schiff base ligand. Moreover, the influence of the weak forces or solvent molecules present in the solid-state structure for the conformational change is also analysed theoretically. This theoretical calculation incorporates two more similar structures, [Fe2LSTACKABOVE′/ABOVEBELOW2/BELOW/STACK]·CH2Cl2 (2) and [Fe2L′2]·2CH3CN (3) (H3L′ = N,N′-bis(salicylidene)-1,3,-diaminopropan-2-ol), for a comparative study. Complex 2 has been reported previously in the literature with the usual binding mode of the ligands. We have repeated its synthesis and recrystallized it from another solvent (acetonitrile) to get complex 3 which is isostructural with 2 but has acetonitrile as solvent molecule. [ABSTRACT FROM AUTHOR]

Five heterobimetallic copper(II)--uranium(VI) complexes [(CuL¹)-UO2 (NO3)2] (1), [{CuL¹(CH3CN)}UO2 (NO3)2] (2), [{CuL¹(CH3COCH3)}-UO2 (NO3)J (3), [{CuL²(CH3CN)}U02 (NO3)2](4), and [{CuL²(CH3COCH3)}-UO2 (NO3)2][{CuL²}UO2 (NO3)2] (5) have been synthesized by reacting the Cu(II)-derived metalloligands [CuL¹] and [CuL²] (where, H2L¹ = N,N'-bis(α-methylsalicylidene)-1,3-propanediamine and H2L² - N,N'-bis(salicylidene)-l,3-propanediamine) with UO2 (NO3)2-6H2O in 1:1 ratio by varying the reaction temperature and solvents. Absorption and fluorescence quenching experiments (steady-state and time-resolved) indicate the formation of 1:1 ground-state charge transfer copper(Il)-uranium(VI) complexes in solution. X-ray single-crystal structure reveals that each complex contains diphenoxido bridged Cu(II)--U(VI) dinuclear core with two chelated nitrato coligands. The complexes are solvated (acetonitrile or acetone) in the axial position of the Cu(Il) in different manner or desolvated. The supramolecular interactions that depend upon the coordinating metalloligands seem to control the solvation. In complexes 2 and 3 a rare NO3- ... NO3- weak interaction plays an important role in forming supramolecular network whereas an uncommon U=O...NO3- weak interaction helps to self-assemble heterobinuclear units in complex 5. The significance of the noncovalent interactions in terms of energies and geometries has been analyzed using theoretical calculations. [ABSTRACT FROM AUTHOR]

The synthesis and crystal-structure determination of three zinc(II) complexes with 2-(1 H-imidazol-1-yl)pyrimidine(imipyr) and 2-(1 H-pyrazol-1-yl)pyrimidine (pyrapyr) ligands are reported. Complexes [Zn(imipyr)2Cl2] ( 1) and[Zn(pyrapyr)2Cl2] ( 2) are mononuclear systems, and [Zn2(pyrapyr)2(Cl)4] ( 3) is a dinuclear complex with two chlorido bridging ligands. In complex 3, the coordination numbers of the two differently coordinated Zn ions are four and six. All complexes were characterized by X-ray crystallography. A high-level theoretical study was performed to rationalize the interesting noncovalent interactions observed in the solid state. All three structures show a peculiar π stacking, which is characterized by the absence of π-π ring-plane overlapping. In this slipped stacking mode, the rings are antiparallely displaced, and alternating C ···N interactions are established. Moreover, complex 3 forms infinite 1D columns by means of double anion-π interactions with pyrapyr. The atoms-in-molecules (AIM) theory proposed by Bader was used to characterize the anion-π and π-π interactions observed in the solid state. A high-level ab initio study (RI-MP2/def2-TZVP level of theory) was performed to analyze the anion-π binding affinity of the pyrapyr ligand coordinated to the transition metal atom. Finally, a CSD search demonstrates that the structure of 3 is quite unique, because dinuclear Zn complexes that contain one tetracoordinate and one hexacoordinate metal center are rare, whereas this combination is common in trinuclear, linear complexes. With bridging chlorido ligands, this simultaneous tetra- and hexacoordination is unprecedented. [ABSTRACT FROM AUTHOR]

Electrophilic fluorophosphonium triflates bearing pyridyl (3[OTf]) or imidazolyl (4[OTf])‐substituents act as intramolecular frustrated Lewis pairs (FLPs) and reversibly form 1 : 1 adducts with CO2 (5+ and 6+). An unusual and labile spirocyclic tetrahedral intermediate (72+) is observed in CO2‐pressurized (0.5–2.0 bar) solutions of cation 4+ at low temperatures, as demonstrated by variable‐temperature NMR studies, which were confirmed crystallographically. In addition, cations 3+ and 4+ actively bind carbonyls, nitriles and acetylenes by 1,3‐dipolar cycloaddition, as shown by selected examples. [ABSTRACT FROM AUTHOR]

Bis-pyridazine tectons support the structure of metallosupramolecular cavitand Cu2L44+, which is capable of selective encapsulation of SiF62− anions by a set of multiple host–guest interactions. [ABSTRACT FROM AUTHOR]

A series of pyridinium-carboxylate salts (1–3) were designed, synthesized and structurally characterized to explore the importance of salt-bridge (SB) interactions in building self-assembled structures. We present a comprehensive analysis of the SB interaction in crystal structures of 4,4′-oxybis(benzoic acid) with substituted aminopyridines where the SBs display extremely well defined geometric preferences. In the solid-state, compound (1) exhibits lone-pair (l.p)⋯(SB)/(SB)⋯π+ assemblies while compound (2) shows a C–H⋯(SB)/(SB)⋯π network. Interestingly, compound (3) exhibits two distinct networks π+⋯(SB)/(SB)⋯(SB)/(SB)⋯π+ and C–H⋯(SB)/(SB)⋯H–C. These extended supramolecular networks are studied and described in detail. The duality of the SBs in stabilizing the π-facial interactions with electron rich and/or electron poor moieties is also described. The energetic and geometric features of salt-bridge interaction are studied and its impact on the resultant supramolecular organization is analyzed using theoretical DFT-D3 calculations. The theoretical study combines the energetic features of the noncovalent forces that participate in the extended network and the characterization of the diverse interactions by means of Bader's theory of 'atoms in molecules'(AIM). [ABSTRACT FROM AUTHOR]

Three Cd(II) complexes [Cd(i-mnt)(DMSO)2]n (1), {[Cd(i-mnt)pn]·2H2O} (2), and [Cd(i-mnt)3][Cd(tren)2]2 (3) harvested from 1,1-dicyanoethylene-2,2-dithiolate (i-mnt2−) and polyamine ligand systems have been designed, synthesized and structurally characterized. Single-crystal X-ray diffraction analysis reveals that these complexes exhibit diverse supramolecular architectures primarily thanks to different coordination modes adopted by (i-mnt2−) and polyamine ligands, and also owing to their disparate conformational flexibility. Indeed, polyamines (pn = 1,2-diamino propane, tren = diethylenetriamine) and (i-mnt2−) ligands demonstrate the impact of the directing effect of the ligands' spatial extension, binding abilities and flexibility on the resulting structures of the complexes. Complex 1 is a 2D coordination polymer, whereas discrete complex 2 involves a cadmium center with a distorted octahedral geometry and forms a hydrogen bonding network of an unprecedented topological type ({411698}{4462} point symbol notation). Complex 3 is a cocrystalline aggregate of one anionic [Cd(i-mnt)3]4− unit flanked by two cationic [Cd(tren)2]2+ units. DFT calculations (M06-2X/def2-TZVP level of theory) were performed in order to quantify the energetic contributions of non-covalent interactions. In 2, the energetics of hydrogen bonding interactions is explored while in the case of 3 unidirectional electrostatic interactions between the counterions are studied. Analyses of Hirshfeld surfaces (HSs) and of two-dimensional fingerprint plots provided another means of quantification of intermolecular contacts experienced by the neutral, cationic, and anionic cadmium complexes. It is found that the calculated contact contributions to the HS of neutral complex 2 are similar to the HS properties of cationic complexes in 3, i.e. being dominated predominantly by H⋯H and S⋯H contacts, despite significant differences in their structures. Moreover, the steady-state luminescence properties of dimethylsulfoxide solutions of the ligand (i-mnt2−) and of complexes 1–3 are also examined. [ABSTRACT FROM AUTHOR]

Two self-assembled hosts are formed from Ag(i) salts and bis-pyrimidyl ligands and X-ray characterized. Both are able to incorporate two anions into the structure combining hydrogen bonding and electrostatic interactions. [ABSTRACT FROM AUTHOR]

A tridentate N,N,O-donor ligand, in the form of a Schiff base of aminoguanidine (LH) with salicylaldehyde, and its Cu(II) complex, [Cu2(LH)2](ClO4)2, have been synthesized. The single crystal X-ray structure of the complex is reported. The complex shows strong DNA binding affinity, with a binding constant value comparable to that of classical intercalators like ethidium bromide. Against the human colon cancer cell line HCT116, the complex shows significant in vitro cytotoxicity with a LD50 value of 20 μM. It is shown that the cytotoxicity of the complex follows the apoptosis mechanism. The complex can also be used for selective spectrophotometric or fluorometric determination of histidine. The binuclear Cu(II) complex shows strong intramolecular antiferromagnetic interaction between the Cu(II) atoms mediated by two bridging phenoxide ligands, with 2J = −656 cm−1. DFT calculations are used to explain the magnetic interaction. [ABSTRACT FROM AUTHOR]

Crystal engineering of coordination complexes has become an important research domain of modern inorganic chemistry. Herein, six Hg(II) coordination compounds containing 2-((pyridin-3-ylmethylene)amino)phenol and 4-((pyridin-4-ylmethylene)amino)phenol ligands were synthesized and characterized by single crystal X-ray crystallography and spectroscopic techniques. The crystal structure of these coordination compounds was studied using geometrical and Hirshfeld analyses as well as theoretical calculations. The results revealed the contribution of π-stacking, as well as hydrogen bonding interactions in the supramolecular architecture of these coordination compounds. This study may provide further insight into elucidating the role of weak non-covalent interactions in the supramolecular assembly of metal-containing compounds. [ABSTRACT FROM AUTHOR]

We describe here the utilization of 1,4-naphthoquinone and 3-iodo-1,4-naphthoquinone motifs as new anion binding sites by hydrogen- or halogen-bonding interactions, respectively. These binding sites have been integrated in bidentate ester based receptors. Emission experiments reveal that both receptors selectively recognize sulfate anions, which induced a remarkable increase of a new emission band attributed to the formation of π-stacking interactions between two 1,4-naphthoquinone units. Absorption spectroscopy and mass spectrometry indicate the disruption of the ester group of the 1,4-naphthoquinone based receptor in the presence of HP2O73−, H2PO4−, F−, AcO− and C6H5CO2− and in the halogenated receptor with HP2O73−, F− and AcO− anions, while the presence of sulfate anions showed the clasical complexation behaviour. The 1H-NMR experiment showed a slow exchange process of the receptors with their sulfate complexes. The binding mode of the receptors with sulfate has been studied by DFT calculations along with the Molecular Electrostatic Potential (MEP) surface computational tool that reveals those parts of the receptors which are more suitable for interacting with anions. [ABSTRACT FROM AUTHOR]