Crystal structure of the coordination polymer catena-poly[[[(acetonitrile-κN)copper(I)]-μ3-1,3-dithiolane-κ3 S:S:S′] hexafluoridophosphate]

The polymeric title compound, [Cu2(C2H3N)2(C3H6S2)2](PF6)2, represents an example of a one-dimensional coordination polymer resulting from the reaction of [Cu(MeCN)4][PF6] with 1,3-dithiolane. The cationic one-dimensional ribbon consists of two copper(I) centers each ligated by one acetonitrile molecule and interconnected through two bridging 1,3-dithiolane ligands. One S-donor site of each ligand is κ1-bound to Cu, whereas the second S atom acts as a four-electron donor, bridging two Cu atoms in a κ4-bonding mode. The positive charge of each copper cation is compensated for by a hexafluoridophosphate counter-ion. In the crystal, the polymer chains are linked by a series of C—H...F hydrogen bonds, forming a supramolecular framework.

Metal Complexes Containing Redox-Active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review

Ligands are innocent when they allow oxidation states of the central atoms to be defined. A noninnocent (or redox) ligand is a ligand in a metal complex where the oxidation state is not clear. Dioxygen can be a noninnocent species, since it exists in two oxidation states, i.e., superoxide (O2−) and peroxide (O22−). This review is devoted to oxidations of C–H compounds (saturated and aromatic hydrocarbons) and alcohols with peroxides (hydrogen peroxide, tert-butyl hydroperoxide) catalyzed by complexes of transition and nontransition metals containing innocent and noninnocent ligands. In many cases, the oxidation is induced by hydroxyl radicals. The mechanisms of the formation of hydroxyl radicals from H2O2 under the action of transition (iron, copper, vanadium, rhenium, etc.) and nontransition (aluminum, gallium, bismuth, etc.) metal ions are discussed. It has been demonstrated that the participation of the second hydrogen peroxide molecule leads to the rapture of O–O bond, and, as a result, to the facilitation of hydroxyl radical generation. The oxidation of alkanes induced by hydroxyl radicals leads to the formation of relatively unstable alkyl hydroperoxides. The data on regioselectivity in alkane oxidation allowed us to identify an oxidizing species generated in the decomposition of hydrogen peroxide: (hydroxyl radical or another species). The values of the ratio-of-rate constants of the interaction between an oxidizing species and solvent acetonitrile or alkane gives either the kinetic support for the nature of the oxidizing species or establishes the mechanism of the induction of oxidation catalyzed by a concrete compound. In the case of a bulky catalyst molecule, the ratio of hydroxyl radical attack rates upon the acetonitrile molecule and alkane becomes higher. This can be expanded if we assume that the reactions of hydroxyl radicals occur in a cavity inside a voluminous catalyst molecule, where the ratio of the local concentrations of acetonitrile and alkane is higher than in the whole reaction volume. The works of the authors of this review in this field are described in more detail herein.

Crystal structures of (acetonitrile-κN)tris(pyridine-4-thioamide-κN)bis(thiocyanate-κN)cobalt(II) acetonitrile disolvate and tetrakis(pyridine-4-thioamide-κN)bis(thiocyanate-κN)nickel(II) methanol pentasolvate

Reaction of Co(NCS)2 or Ni(NCS)2 with pyridine-4-thioamide in different solvents led to the formation of two compounds with composition [Co(NCS)2(C2H3N)(C6H6N2S)3]·2CH3CN (1) and [Ni(NCS)2(C6H6N2S)4]·5CH3OH (2), respectively. The asymmetric unit of compound 1 consists of one cobalt(II) cation, two thiocyanate anions, three pyridine-4-thioamide ligands, one coordinating and two solvate acetonitrile molecules. One of the two acetonitrile solvate molecules is disordered over two sets of sites in a 0.62:0.38 ratio. The asymmetric unit of compound 2 comprises of one nickel(II) cation, two thiocyanate anions, four N-bonding pyridine-4-thioamide ligands and five methanol solvate molecules. In compound 1, the cobalt(II) cations are octahedrally coordinated into discrete complexes by two terminal N-bonding thiocyanate anions, the N atoms of three pyridine-4-thioamide ligands and one acetonitrile molecule. Additional acetonitrile solvate molecules are located between the complexes,. The complexes and solvate molecules are linked via intermolecular hydrogen bonding into a three-dimensional framework. In compound 2, the nickel(II) cations are likewise octahedrally coordinated by two terminal N-bonded thiocyanate anions and four N-bonding pyridine-4-thioamide ligands into discrete complexes. From their arrangement cavities are formed, in which the methanol solvate molecules are located. Again, the complexes and solvate molecules are linked into a three-dimensional framework by intermolecular hydrogen bonding.

2-[Tris(pyridin-2-yl)methyl]pyridiniumtrans-bis(acetonitrile)tetrachloridoruthenate(III) acetonitrile monosolvate

The asymmetric unit of the title compound, [(C5H4N)3C(C5H5N)][RuCl4(CH3CN)2]·CH3CN, contains one 2-[tris(pyridin-2-yl)methyl]pyridinium cation, onetrans-bis(acetonitrile)tetrachloridoruthenate(III) anion and one acetonitrile solvent molecule. The RuIIIion is coordinated by four Cl−anions in the equatorial plane and by two acetonitrile ligands in the axial positions, forming a distorted octahedral geometry. The cation, the monoprotonated species of tetrakis(pyridin-2-yl)methane, forms an intramolecular N—H...N hydrogen bond between the pyridinium ring and one of the pyridine rings. The complex anions are linked to each otherviaC—H...Cl hydrogen bonds, forming an undulating sheet parallel to theacplane. A C—H...N hydrogen bond between the cation and the anion is also observed. The solvate acetonitrile molecule forms C—H...N and C—H...Cl hydrogen bonds, respectively, with the cation and the anion.

Crystal structure and electrochemical properties of [Ni(bztmpen)(CH3CN)](BF4)2{bztmpen isN-benzyl-N,N′,N′-tris[(6-methylpyridin-2-yl)methyl]ethane-1,2-diamine}

The mononuclear nickel title complex (acetonitrile-κN){N-benzyl-N,N′,N′-tris[(6-methylpyridin-2-yl)methyl]ethane-1,2-diamine}nickel(II) bis(tetrafluoridoborate), [Ni(C30H35N5)(CH3CN)](BF4)2, was prepared from the reaction of Ni(BF4)2·6H2O withN-benzyl-N,N′,N′-tris[(6-methylpyridin-2-yl)methyl]ethane-1,2-diamine (bztmpen) in acetonitrile at room temperature. With an open site occupied by the acetonitrile molecule, the nickel(II) atom is chelated by five N-atom sites from the ligand and one N atom from the ligand, showing an overall octahedral coordination environment. Compared with analogues where the 6–methyl substituent is absent, the bond length around the Ni2+cation are evidently longer. Upon reductive dissociation of the acetronitrile molecule, the title complex has an open site for a catalytic reaction. The title complex has two redox couples at −1.50 and −1.80 V (versus Fc+/0) based on nickel. The F atoms of the two BF4−counter-anions are split into two groups and the occupancy ratios refined to 0.611 (18):0.389 (18) and 0.71 (2):0.29 (2).

Crystal structure of bis(acetonitrile-κN)bis(4-benzoylpyridine-κN)bis(thiocyanato-κN)cobalt(II)

The crystal structure of the title compound, [Co(NCS)2(C2H3N)2(C12H9NO)2], consists of cobalt(II) cations that are octahedrally coordinated by the N atoms of two terminal thiocyanate anions, two acetonitrile molecules and two 4-benzoylpyridine ligands. The discrete complexes are located on centres of inversion. They are connected by weak intermolecular C—H...O and C—H...S hydrogen-bonding interactions between one of the pyridine H atoms and the carbonyl O atom, and between one of the methyl H atoms of the acetonitrile molecule and the thiocyanate S atoms into layers parallel to (101). No pronounced intermolecular interactions are observed between these layers.

[1–9-NαC]-Linusorb B3 (cyclolinopeptide A) acetonitrile disolvate

The title compound, C57H85N9O9·2C2H3N [systematic name:cyclo-(prolyl-prolyl-phenylalanyl-phenylalanyl-leucyl-isoleucyl-isoleucylleucyl-valyl) acetonitrile disolvate; synonym: cyclolinopeptide acetonitrile disolvate], is a polypeptide with nine amino acids,viz.NαC-(Pro1–Pro2–Phe3–Phe4–Leu5–Ile6–Ile7–Leu8–Val9). It was extracted from flaxseed oil and crystallized from acetonitrile as a disolvate. In the title molecule, there are four intramolecular N—H...O hydrogen bonds. One of the two acetonitrile molecules is hydrogen bonded to Phe3viaan N—H...N hydrogen bond, while the second acetonitrile molecule is located at the other side of the peptide ring and is linked to the title molecule by a C—H...N hydrogen bond. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming chains along thea-axis direction. The chains are linked by C—H...O hydrogen bonds, forming undulating layers parallel to theacplane.

A cadmium(II) coordination polymer formed from a third generation tetratopic tris(pyrazolyl)methane ligand

The reaction of a third generation tetratopic tris(pyrazolyl)methane ligand, namely 1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene {1,2,4,5-C6H2[CH2OCH2C(pz)3]4,L4}, and [Cd2(thf)5](BF4)4(thf is tetrahydrofuran) produces the coordination polymercatena-poly[[[bis[acetonitrilecadmium(II)]-μ4-1,2,4,5-{[2,2,2-tris(1H-pyrazol-1-yl)ethoxy]methyl}benzene] tetrakis(tetrafluoroborate)]–diethyl ether–acetonitrile (1/2/2)], {[Cd2(CH3CN)2(C54H54N24O4)](BF4)4·2C4H10O·2CH3CN}n. The CdIIcenter is coordinated in a κ3-fashion by one tris(pyrazolyl)methane group and in a κ2–κ0fashion by another, while the sixth coordination site on the CdIIcation is occupied by an acetonitrile molecule. This bonding mode of the ligand generates an infinite one-dimensional structure built upon 32-atom metallomacrocycles connected by the C6H2spacer. This compound is isostructural with the silver(I) analogue of this ligand,i.e.{[Ag2(L4)](BF4)2·4CH3CN}n, thus showing the tendency of this system to form metal-based macrocyclic architectures.

Crystal structure of tetrakis[μ2-2-(dimethylamino)ethanolato-κ3N,O:O]di-μ3-hydroxido-dithiocyanato-κ2N-dichromium(III)dilead(II) dithiocyanate acetonitrile monosolvate

The tetranuclear complex cation of the title compound, [Cr2Pb2(NCS)2(OH)2(C4H10NO)4](SCN)2·CH3CN, lies on an inversion centre. The main structural feature of the cation is a distorted seco-norcubane Pb2Cr2O6cage with a central four-membered Cr2O2ring. The CrIIIion is coordinated in a distorted octahedron, which involves two N atoms of one bidentate ligand and one thiocyanate anion, two μ2-O atoms of 2-(dimethylamino)ethanolate ligands and two μ3-O atoms of hydroxide ions. The coordination geometry of the PbIIion is a distorted disphenoid, which involves one N atom, two μ2-O atoms and one μ3-O atom. In addition, weak Pb...S interactions involving the coordinating and non-coordinating thiocyanate anions are observed. In the crystal, the complex cations are linked through the thiocyanate anionsviathe Pb...S interactions and O—H...N hydrogen bonds into chains along thecaxis. The chains are further linked togetherviaS...S contacts. The contribution of the disordered solvent acetonitrile molecule was removed with the SQUEEZE [Spek (2015).Acta Cryst.C71, 9–18] procedure inPLATON. The solvent is included in the reported molecular formula, weight and density.

N,N,N′,N′,N′′,N′′-Hexamethylguanidinium di-μ3-chlorido-tetra-μ2-chlorido-decachloridotetrabismuthate acetonitrile disolvate

The asymmetric unit of the solvated title compound, (C7H18N3)4[Bi4Cl16]·2CH3CN, comprises two cations, one half [Bi4Cl16]4−ion and one acetonitrile molecule. OneN,N,N′,N′,N′′,N′′-hexamethylguanidinium ion shows orientational disorder and two sets of N- and C-atom positions were found, with an occupancy ratio of 0.941 (2):0.059 (2). The second cation is not disordered. The C—N bond lengths in the two guanidinium ions range from 1.334 (17) to 1.341 (17) Å, indicating double-bond character and pointing towards charge delocalization within the NCN planes. The four BiIIIions are coordinated by six chloride ions in distorted octahedral manner. Two [Bi2Cl8]2−dimers are fused together, forming a centrosymmetric tetranuclear [Bi4Cl16]4−cluster. The bond lengths of bismuth to the terminal chlorides [2.4982 (7)–2.5509 (6) Å] are shorter than those of the double and triply bridging ones [2.7052 (6)–3.0320 (6) Å]. The acetonitrile solvent molecule is disordered over two positions, with an occupancy ratio of 0.818 (4):0.182 (4) for the two orientations. The crystal structure is stabilized by a three-dimensional network of C—H...Cl hydrogen bonds.