Crystal structures of two (5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)iron(III) complexes

Reported in this contribution are the synthesis and crystal structures of two new FeIII complexes of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (HMC), namely, dichlorido(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)iron(III) chloride, [FeCl2(C16H36N4)]Cl or cis-[FeCl2(rac-HMC)]Cl (1), and dichlorido(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)iron(III) tetrachloridoferrate, [FeCl2(C16H36N4)][FeCl4] or trans-[FeCl2(meso-HMC)][FeCl4] (2). Single-crystal X-ray diffraction studies revealed that both 1 and 2 adopt a pseudo-octahedral geometry, where the macrocycles adopt folded and planar geometries, respectively. The chloride ligands in 1 are cis to each other, while those in 2 have a trans configuration. The relevant bond angles in 1 deviate substantially from an ideal octahedral coordination geometry, with the angles between the cis substituents varying from 81.55 (5) to 107.56 (4)°, and those between the trans-ligating atoms varying from 157.76 (8) to 170.88 (3)°. In contrast, 2 adopts a less strained configuration, in which the N—Fe—N angles vary from 84.61 (8) to 95.39 (8)° and the N—Fe—Cl angles vary from 86.02 (5) to 93.98 (5)°.

HYDROLYSIS OF RHENIUM(III) CLUSTER COMPOUNDS

Study of hydrolysis of cis-tetrachlorodi-m-carboxylates of dirhenium (III) was carried out due to the electronic adsorption and IR spectroscopy and pHmeter. As a result, itwas shown that the hydrolysis is a multistage process which can be attributed to the reactions of the pseudo-first order. It is also shown that the electronic absorption spectroscopy (EAS) is a reliable method of investigation to study the hydrolysis of rhenium (III) complex compounds. This conclusion is based on the fact that in the systems with halide and carboxylic ligands, each of the five structural types can be clearly identified by the EAS in the region of both d–d* electron transition and charge transfer transition of L*Hal ®Re type. It is shown that with the increase in the length of the alkyl group and in its branching, the hydrolysis rate decreases, as a result of a change in the positive inductive effect of these groups and, consequently, an increase in the strengthening of quadruple Re–Re bond. In addition, with the help of the EAS, a transition of the chloride ligands to OHgroups can be observed. As a result of the study, a hydrolysis route, which initially leds to the gradual replacement of the chloride ligands of a complex compound with OH groups, and subsequently to the conversion of Re(III) compounds into the derivative of Re(IV) was proposed. The dependence of resistance to hydrolysis on the structure of the complex compound, the temperature and pH was determined. It allowed to predict the stability of the investigated compounds while their usage as biologically active substances and reagents in the synthesis of new compounds. The obtained results allow us to presence of anticancer, cytostabilizing and other biological activities is the coordination of Re(III) complex compounds with the components of biomolecules (proteins, DNA).

HYDROLYSIS OF RHENIUM(III) CLUSTER COMPOUNDS

Study of hydrolysis of cis-tetrachlorodi-m-carboxylates of dirhenium (III) was carried out due to the electronic adsorption and IR spectroscopy and pHmeter. As a result, itwas shown that the hydrolysis is a multistage process which can be attributed to the reactions of the pseudo-first order. It is also shown that the electronic absorption spectroscopy (EAS) is a reliable method of investigation to study the hydrolysis of rhenium (III) complex compounds. This conclusion is based on the fact that in the systems with halide and carboxylic ligands, each of the five structural types can be clearly identified by the EAS in the region of both d–d* electron transition and charge transfer transition of L*Hal ®Re type. It is shown that with the increase in the length of the alkyl group and in its branching, the hydrolysis rate decreases, as a result of a change in the positive inductive effect of these groups and, consequently, an increase in the strengthening of quadruple Re–Re bond. In addition, with the help of the EAS, a transition of the chloride ligands to OHgroups can be observed. As a result of the study, a hydrolysis route, which initially leds to the gradual replacement of the chloride ligands of a complex compound with OH groups, and subsequently to the conversion of Re(III) compounds into the derivative of Re(IV) was proposed. The dependence of resistance to hydrolysis on the structure of the complex compound, the temperature and pH was determined. It allowed to predict the stability of the investigated compounds while their usage as biologically active substances and reagents in the synthesis of new compounds. The obtained results allow us to presence of anticancer, cytostabilizing and other biological activities is the coordination of Re(III) complex compounds with the components of biomolecules (proteins, DNA).

Stability of cubic tin sulphide nanocrystals: role of ammonium chloride surfactant headgroups

Ammonium chloride ligands reduce surface energies, bind preferably to the cubic π-phase and destabilize the orthorhombic phase of SnS.

Changes in the oxidation state of Pt single-atom catalysts upon removal of chloride ligands and their effect for electrochemical reactions

The activity of Pt single-atom catalysts can be maximized by controlling the oxidation state of the single-atoms.

Crystal structure of [{FeCl3}2(μ-PCHP)2] [PCHP = 1,3-bis(2-diphenylphosphanylethyl)-3H-imidazol-1-ium] with an unknown solvent

The crystal structure of the title compound, bis{μ-1,3-bis[2-(diphenylphosphanyl)ethyl]-1H-imidazole-κ2 P:P′}bis[trichloridoiron(III)], [Fe2Cl6(C31H31N2P2)2] or [{FeCl3}2(μ-PCHP)2] (PCHP = C31H31N2P2), consists of dinuclear complexes that are located about centres of inversion. The FeIII cation is in a distorted trigonal–bipyramidal coordination with three chloride ligands located in the trigonal plane and two P atoms of symmetry-related PCHP ligands occupying the axial positions. Within the centrosymmetric complex, a pair of intramolecular C—H...Cl hydrogen bonds between aromatic CH groups and chloride ligands are found. Individual complexes are linked into layers parallel to (\overline{1}01) by intermolecular C—H...Cl hydrogen bonds. No pronounced intermolecular interactions occur between these layers. This arrangement leaves space for disordered solvent molecules. Electron density associated with these additional solvent molecules was removed with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s).

Crystal structure of the [(1,3-dimesityl-1H-imidazol-3-ium-2-yl)methanolato]copper(II) chloride dimer: insertion of formaldehyde into a copper–carbene bond

The crystal structure of bis[μ-(1,3-dimesityl-1H-imidazol-3-ium-2-yl)methanolato-κ2 O:O]bis[dichloridocopper(II)], [Cu2Cl4(C22H26N2O)2], is reported. The complex is assumed to have formed via the insertion of formaldehyde into the copper–carbon bond in an N-heterocyclic carbene complex of copper(I) chloride. The structure of the binuclear molecule possesses a crystallographically centrosymmetric Cu2O2 central core with the O atoms bridging between the CuII atoms and thus Z′ = 0.5. The copper centres are further ligated by two chloride ligands, resulting in the CuII atoms residing in a distorted square-planar environment. The Cu—O bond lengths are shorter than those previously reported in structures with the same central Cu2O2 motif. The complex displays C—H...Cl interactions involving the H atoms of the heterocycle backbone and the chloride ligands of a neighbouring molecule.