Stabilization of Tetrachloride with Mn (II) and Co (II)Complexes and 4-Tert-Butylpyridinium Organic Cation: Elaboration of the Structure and Hirshfeld Surface, Optical, Spectroscopic and Thermal Analyses

[C9H14N]2[MnCl4] (I) and [C9H14N]2[CoCl4] (II) are isostructural compounds produced via gradual evaporation at room temperature. Both compounds consolidate in the tetragonal space group I4¯2d (No. 122), as shown by single-crystal X-ray diffraction observations. A slightly deformed tetrahedral geometry is formed by four chloride atoms around each cation MII (M = Mn or Co). The [C9H14N]+ groups and the isolated [MCl4]2− units are connected via C–H…Cl and N–H…Cl H-bonds to form sheets parallel to the (101¯), (011), (01¯1) and (101) planes. The morphology and the chemical composition of compounds (I) and (II)were determined here using SEM and EDX. The functional groups contained in both compounds were determined using FT-IR spectroscopy. The study of the optical characteristics showed that the two compounds exhibited semiconductor behavior. The thermal analysis (TGA-DTA) was used to determine their thermal stability.

Significant photodegradation of carcinogenic organic dyes by a 1D supramolecular heteroleptic Cu(ii) complex under sunlight irradiation

The crucial role of supramolecular interactions in the self-assembly and architecture of the heteroleptic Cu(II) coordination polymer has been investigated and its ability to degrade organic molecules using sunlight.

Novel primary amide-based cationic metal complexes: green synthesis, crystal structures, Hirshfeld surface analysis and solvent-free cyanosilylation reaction

A new symmetrical and flexible primary amide functionalized ligand, 2,2'-(ethane-1,2-diylbis((pyridin-2-ylmethyl)azanediyl))diacetamide (2-BPEG), has been synthesized and structurally characterized. Using this multidentate ligand, four novel metal complexes, namely [Cu(2-BPEG)](ClO4)2·0.5H2O (1), [Zn(2-BPEG)](ClO4)2 (2), [Zn(2-BPEG)](ZnCl4)·H2O (3) and [Cd(2-BPEG)(H2O)](ClO4)2·H2O (4), have been synthesized under ambient conditions and characterized by elemental, spectroscopic and thermal analysis, and single and powder X-ray diffraction. Complexes 1-3 are hexacoordinated with an N4O2 donor set (provided by the hexadentate 2-BPEG ligand), while complex 4 is heptacoordinated with an additional coordinated water molecule. In all cases, the 2-BPEG ligand acts as a hexadentate ligand. A change in the starting metal salt has resulted in the formation of 2 and 3 with different tetrahedral anions, ClO4- and ZnCl4-, respectively. This has provided an opportunity to showcase anion-directed supramolecular networks for these compounds. Compounds 1, 2 and 4 with perchlorate anions show similar and comparable intermolecular interactions in their 3D networks. On the other hand, the supramolecular self-assembly of 3 is dominated by a variety of intermolecular interactions such as C-HCl, N-HCl, O-HCl and C-HO due to the presence of a tetrachlorozincate(ii) ion. Moreover, the role of weak intermolecular interactions in the crystal packing has been analysed and quantified using Hirshfeld surface analysis. Furthermore, compound 4 exhibiting an open Lewis acid site has been found to be a very efficient and recyclable heterogeneous catalyst for the solvent-free cyanosilylation of various aldehydes with trimethylsilyl cyanide (TMSCN) producing the corresponding trimethylsilyl ether in high yields.

Hydrogen-Bonded Frameworks of Mercury(II) Complexes with Pyridinedicarboxylic Acids

Three novel mercury(ii) coordination compounds, [HgCl(2,4-pydcH2)(2,4-pydcH)]·2H2O (1) and [HgCl(2,6-pydcH)(H2O)]·3H2O (2) that exhibit hydrogen-bonded 3D frameworks, and [Hg(2,6-pydcH)2]·2H2O (3), exhibiting only hydrogen-bonded 1D chains (2,4-pydcH2 = pyridine-2,4-dicarboxylic acid; 2,6-pydcH2 = pyridine-2,6-dicarboxylic acid), were prepared in the reactions of the corresponding pyridinedicarboxylic acid with mercury(ii) chloride or mercury(ii) acetate. Compounds 1–3 were prepared by conventional solution synthesis. Only the hydrogen-bonded 1D chain of 3 was robust enough to be prepared by mechanochemical synthesis. The crystal structures of 1–3 were determined by the single-crystal X-ray diffraction method. Neutral 2,4-pydcH2 and partially deprotonated 2,4-pydcH− act as N,O-bidentate ligands in the structure of 1 whereas crystal structure analysis reveals O,N,O′-tridentate 2,6-pydcH− ligand in the structures of 2 and 3. Compounds 1–3 were characterised by IR spectroscopy in the solid state, and compounds 1 and 2 were also characterised by 1H and 13C NMR spectroscopy in DMSO solution. Thermal properties of 1–3 were also investigated. NMR data support a collapse of the hydrogen-bonded frameworks of 1 and 2 in DMSO solution, and the existence of monomeric species in DMSO solutions.

Testing the limits of halogen bonding in coordination chemistry

To test the limit of halogen bonds fine-tuning of electron density was performedviaintroduction of heteroatoms and metal cations.

(8-Amino-quinoline-κ(2)N,N')bis-(1,1,1,5,5,5-hexa-fluoro-pentane-2,4-dionato-κ(2)O,O')cobalt(II)

In the title compound, [Co(C₅HF₆O₂)₂(C₉H₈N₂)], the Co^II centre exhibits a pseudooctahedral coordination geometry, comprising two N-atom donors from the bidentate amino­quinoline ligand and four O-atom donor atoms from two bidentate chelating 1,1,1,5,5,5-hexafluoropentane-2,4-dionate ligands. In the crystal, molecules are linked via pairs of N—H⋯O hydrogen bonds, forming inversion dimers. These dimers are further connected through π–π interactions between neighbouring quinoline rings [centroid–centroid distance = 3.472 (2) Å], and stack along the c axis.

[(4-Bromo-phen-yl)(2-pyridyl-methyl-idene)amine-κN,N']bis-(1,1,1,5,5,5-hexa-fluoro-pentane-2,4-dionato-κO,O')cobalt(II)

In the title complex, [Co(C₅HF₆O₂)₂(C₁₂H₉BrN₂)], the Co^II atom exhibits a pseudo-octa­hedral coordination geometry, comprising two N-donor atoms from a bidentate chelate (4-bromo­phen­yl)(2-pyridyl­methyl­idene)amine (ppa^Br) ligand [Co—N = 2.098 (2) and 2.209 (2) Å] and four O-donor atoms from two bidentate chelate 1,1,1,5,5,5-hexa­fluoro­pentane-2,4-dionate (hfac) ligands [Co—O range = 2.0452 (19)–2.0796 (19) Å]. The packing of the structure involves weak π–π inter­actions between the pyridyl and benzene rings of neighbouring ppa^Br ligands [centroid–centroid distance = 3.928 (2) Å] and inter­actions between the Br atom on the ppa^Br ligand and the hfac ligand [Br⋯C = 3.531 (2) Å].

Binding mechanisms in supramolecular complexes

Supramolecular chemistry has expanded dramatically in recent years both in terms of potential applications and in its relevance to analogous biological systems. The formation and function of supramolecular complexes occur through a multiplicity of often difficult to differentiate noncovalent forces. The aim of this Review is to describe the crucial interaction mechanisms in context, and thus classify the entire subject. In most cases, organic host-guest complexes have been selected as examples, but biologically relevant problems are also considered. An understanding and quantification of intermolecular interactions is of importance both for the rational planning of new supramolecular systems, including intelligent materials, as well as for developing new biologically active agents.

Establishing amide...amide reliability and synthon transferability in the supramolecular assembly of metal-containing one-dimensional architectures

On the basis of a combination of new structural data (eleven single-crystal structure determinations are presented) and information from the Cambridge Structural Database, it has been shown that self-complementary hydrogen-bond based amide...amide dimers can be relied upon as effective supramolecular synthons for the assembly and organization of acac- and paddle-wheel complexes of a variety of metal(II) ions. The targeted molecular recognition event and intended extended one-dimensional motif appear with a supramolecular yield of 78% (a total of 28 structures were examined). Despite the fact that the hydrogen bonds that give rise to the R2(2)(8) motif can be disrupted by both carboxylate- and acac-ligands, as well as by solvent molecules, they remain remarkably resilient and therefore represent useful synthetic tools in inorganic crystal engineering.

Investigation on the reactivity of dithiophosphonato/dithiophosphato Ni(II) complexes towards 2,4,6-tris-2-pyridyl-1,3,5-triazine: developments and new perspectives

The reactions between tptz and differently substituted dithiophosphonato [Ni(ROpdt)2] [ROpdt = (RO)(4-MeOC6H4)PS2-; R = Et (2); Pr (3); i-Pr (4); Bu (5)] and dithiophosphato [Ni((EtO)2PS2)2] (6) Ni(II) complexes have been investigated, and the characterisation of the resulting neutral mixed complexes (2.tptz)-(6.tptz) is reported. In all these complexes, tptz forces one of the two dithiophosphonato/dithiophosphato ligands to behave as a monodentate ligand, a coordination mode rarely found in analogous Ni(II) phosphorodithioato complexes. A comparison has been performed between the Ni-S bond distances of the new complexes and those of isologous dithiophosphonato, dithiophosphato and dithiophosphito Ni(II) square-planar complexes, and of their penta- and hexa-coordinated adducts. The results, also supported by DFT calculations, are discussed and explained in terms of the structural trans-effect (STE). The reactivity of 2.tptz towards AgNO3 and CuSO4 to yield the complex [Ni(EtOpdt)(tptz)(H2O)]NO3 (7), and the dimer [(Ni(tptz)(mu-SO4)(H2O)]2.6H2O (8), respectively, is consistent with the proposed bonding models.

trans-Tetra-aqua-bis(nicotinamide-κN)cadmium(II) biphenyl-4,4'-disulfonate

In the title compound, [Cd(C₆H₆N₂O)₂(H₂O)₄](C₁₀H₈O₆S₂), the Cd^II ion is located on a crystallographic inversion centre. An octa­hedral coordination geometry is defined by four water mol­ecules in one plane, and two trans N-atom donors of the nicotinamide ligands. The biphenyl-4,4′-disulfonate anion also lies on a crystallographic inversion centre. In the crystal structure, the complex cations are connected to the counter-anions via N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional network.

Aqua-bis(nicotinamide-κN)(thio-cyanato-κN)copper(II)

In the title compound, [Cu(NCS)(2)(C(6)H(6)N(2)O)(2)(H(2)O)], the Cu atom adopts a square-based pyramidal CuN(4)O coordination, with the water O atom in the apical position. The pairs of N-bonded nicotinamide ligands and thio-cyanate anions in the basal plane are in a trans configuration. In the crystal structure, the mol-ecules are connected into sheets by N-H⋯O and O-H⋯O hydrogen bonds.

Investigation into the reactivity of the coordinatively unsaturated phosphonodithioato [Ni(MeOpdt)2] towards 2,4,6-tris(2-pyridyl)-1,3,5-triazine: goals and achievements

The reaction between the coordinatively unsaturated phosphonodithioato complex [Ni(MeOpdt)2] (1) [MeOpdt = (MeO)(4-MeOC(6)H(4))PS2-] and tptz [2,4,6-tris(2-pyridyl)-1,3,5-triazine] has been investigated. Spectrophotometric and conductometric titrations showed the formation of a neutral and an ionic species, i.e. [Ni(MeOdtp)2(tptz)] (2) and [Ni(tptz)2](MeOdtp)2 (3), in correspondence to 1 : 1 and 2 : 1 tptz : ratios, respectively. XRD studies confirmed the formation of both complexes isolated in the compounds 2.MeOH and 3.4H(2)O. In the neutral complex 2 the central Ni(II) ion features a distorted octahedral coordination, achieved through three N-atoms of tptz and three S-atoms belonging to two MeOpdt anions, one of which unexpectedly acts as a monodentate S-donor. In 3.4H(2)O, the two phosphonodithioato anions are non-coordinating and counterbalance the charge of the [Ni(tptz)2](2+) distorted octahedral complex. From the reaction 2 of with I2 and Br2, crystals of [Ni(tptz)2](I3)2 (5) and [Ni(tptz)Br(micro-Br)]2 (6) have been obtained. The dinuclear complex 6 features a structure showing tubular canals with openings of about 6 x 6 A.

Metallotectons: using enantiopure tris(dipyrrinato)cobalt(iii) complexes to build chiral molecular materials

Resolution of a tricarboxylic acid derived from a chiral tris(dipyrrinato)cobalt(III) complex provides a series of enantiopure metallotectons that crystallise as porous hydrogen-bonded networks.