Kandasamy Chinnakali

The crystal structure, equilibrium and spectroscopic studies of bis(dialkyldithiocarbamate) copper(II) complexes [Cu2(R2dtc)4] (dtc=dithiocarbamate)

Abstract Four copper(II) complexes of bis(dialkyldithiocarbamate) [Cd(R2dtc)2] (R=Me, Et, Pr, i-Pr; dtc=dithiocarbamate) have been prepared and characterized by elemental analysis, IR and ESR spectra studies. Their equilibrium constants (K), determined by a UV–vis spectrometry in EtOH, were influenced by the alkyl groups in the following order: i-Pr>n-Pr≈Et>Me. The single crystal structures of complex [Cu2(R2dtc)4] have been determined using X-ray diffraction methods. The compounds [Cu2(Et2dtc)4] and [Cu2(Pr2dtc)4] are built of centrosymmetric neutral dimeric [Cu2(R2dtc)4] entities. The copper atom lies in a distorted square–pyramidal environment. The four equatorial donors are two bidentate chelate sulfur atoms from two dtc ligands. One of the sulfur atoms from the third dtc ligand acts as a bridging ligand occupying the apical position of the symmetry-related copper atom in the dimer structure, which is viewed as two edge-sharing distorted square–pyramids. The structure of [Cu2(i-Pr2dtc)4] is square planar with an exactly planar CuS4 unit and nearly planar NCS2 moieties. The Cu–S distances shows small decreases along the series n-Pr>Et>i-Pr, the biggest change being for the diisopropyl complex. The alkyl substituents at the nitrogen atom affect their coordination number and Cu⋯Cu distance. In the solid, [Cu2(n-Pr2dtc)4] has the shortest Cu⋯Cu distance and [Cu(i-Pr2dtc)2] has the longest one.

Preparation, crystal structure, spectroscopic and magnetic characterisation of acetatobis(di-2-pyridylamine)copper(II) tetrafluoroborate and μ-carbonato-tetrakis(di-2-pyridylamine) dicopper(II) bistetrafluoroborate tetrahydrate

Abstract The crystal structures of [Cu(dpyam)2(O2CCH3)][BF4] (1) and [Cu2(dpyam)4(CO3)][BF4]2·4H2O (2) have been determined by X-ray analysis. 1 involves the distortion of the CuN4O2 chromophore towards a square pyramidal (4+1+1*) stereochemistry which is best described as involving a square-pyramidal distorted octahedral stereochemistry of the six-coordinate CuN4OO′ chromophore. Compound 2 has a dinuclear cation with five-coordinate copper(II) ions bridged asymmetrically by a bidentate carbonate ligand. Both copper(II) ions predominantly involve the distorted square-pyramidal (4+1) stereochemistry of the CuN3ON′ chromophore. The polycrystalline ESR spectra of 1 and 2 are exchange coupled and temperature independent. In 2 the room temperature effective magnetic moment of 1.34 μB indicates the partial spin pairing by antiferromegnetic coupling.

X-ray photoelectron spectral study of the planar NiS4, NiS2PCl and NiS2P2 chromophores and X-ray crystal structure of piperidinedithiocarbamatobis(triphenylphosphine) nickel(II) perchlorate triphenylphosphine monohydrate

Abstract An X-ray photoelectron spectral study on the complexes bis(diethyldithiocarbamato) nickel(II), Ni(dedtc) 2 ( 1 ), bis(diethanoldithiocarbamato) nickel(II), Ni(deadtc) 2 ( 2 ), chlorodiethyldithiocarbamatotriphenylphosphine nickel(II), Ni(dedtc)Cl (PPh 3 ) ( 3 ) and diethyldithiocarbamatobis(triphenylphosphine) nickel(II) perchlorate, [Ni(dedtc)(PPh 3 ) 2 ]ClO 4 ( 4 ) with NiS 4 , NiS 4 (electron-withdrawing alkyl substituent) NiS 2 PCl and NiS 2 P 2 chromophores, respectively was made. All the chromophores except NiS 2 P 2 showed similarity in binding energy values with respect to various core level electrons. The nickel 2p 3 2 binding energy value for the NiS 2 P 2 chromophore was significantly different (854.1 eV), indicating an excessive positive charge on the nickel ion. This observation is in line with solution studies by cyclic voltammetry. A one-electron reduction potential was observed to be the minimum for the NiS 2 P 2 chromophore compared to the others. Alkyl substitution does not alter the binding energy values of the nickel 2p 3 2 level as observed earlier. Highly significant negative ΔE values for sulfur 2 p electron binding energies indicate the localization of electronic charge on sulfur. Also, the crystal structure of the complex [Ni(pipdtc)(PPh 3 ) 2 ]ClO 4 (PPh 3 ) ∗d H 2 O (pipdtc = piperidine dithiocarbamate) prepared by the reaction between Ni(pipdtc) 2 and PPh 3 in CH 2 Cl 2 ue5f8CH 3 OH was determined.

Structure of bis(dipropyldithiocarbamate) cadmium(II), [Cd2(n-Pr2dtc)4] (dtc = dithiocarbamate)

The cadmium complex of bis(dipropyldithiocarbamate), [Cd2(n-Pr2dtc)4] (dtc = dithiocarbamate) was crystallized from ethylether. It crystallizes in the monoclinic system, space group P2I/c, with lattice parameters, a = 8.2532(1), b = 19.4519(1), c = 13.4163(2) Å, β = 99.243(1)°, and Z = 4. The X-ray single-crystal structure of [Cd2(n-Pr2dtc)4] reveals that the complex is binuclear in the solid state and the Cd atom has a distorted square-pyramidal coordination environment and four equatorial donors are the two bidentate chelate sulfur atoms from two dtc ligands, of which the sulfur atom from the bridging dtc ligand occupies the apical position of the symmetry-related Cd atom in the dimer structure.

The crystal structures and electronic properties of bis(di-2-pyridylamine)copper(II), bis(tetrafluoroborate) and bis[bis-aquabis(di-2-pyridylamine)copper(II)] sulfate heptahydrate

Abstract In the [Cu(C 10 H 9 N 3 ) 2 ][BF 4 ] 2 ( 1 ) complex, the Cu(II) ion is in a compressed tetrahedral environment of four N atoms from two di-2-pyridylamine ligands, with an average Cu–N distance of 1.962(7) A; the dihedral angle between the N–Cu–N planes of the two ligands is 55.0(2)°. The asymmetric unit of [Cu(C 10 H 9 N 3 ) 2 (H 2 O) 2 ][SO 4 ]·7H 2 O ( 2 ) contains two units of one-half [Cu(C 10 H 9 N 3 ) 2 ] moieties (the other half is inversion related), one sulfate and nine water molecules. Each Cu(II) ion involves the elongated rhombic octahedral CuN 4 O 2 chromophore, and is surrounded by four N atoms from the two inversion related dpyam ligands, with an average Cu–N distance of 2.019(2) A. The axial positions of Cu(1) are occupied by the centrosymmetrically related O atoms of the two water molecules at 2.496(3) A, giving it a tetragonally distorted Cu(1)N 4 O 2 octahedron. Similarly, the inversion related water oxygens at 2.465(3) A give a Cu(2)N 4 O 2 chromophore. The electronic and ESR spectra of 1 and 2 are consistent with the compressed tetrahedral and the elongated rhombic octahedral stereochemistries, respectively, as reported for other related complexes.

The crystal and molecular structures of di-μ-hydroxy-bis(di-2-pyridylamine)dinitratodicopper(II) and aqua-μ-formato-triformato-bis(di-2-pyridylamine)dicopper(II) monohydrate

Abstract The preparation, magnetic and spectroscopic properties, crystal and molecular structures of binuclear complexes of formulae [Cu2(dpyam)2(OH)2(ONO2)2] (I), [Cu2(dpyam)2(O2CH)4(OH2)].H2O (II) are described. (I) consists of pairs of copper atoms linked by two hydroxo bridges. The co-ordination geometry at each copper atom is distorted square-pyramidal, the basal plane consisting of two hydroxo oxygen atoms and two nitrogen atoms from a dpyam ligand, while the axial co-ordination sites are occupied by nitrate oxygen atoms. The copper(II) ions in (II) are also in a distorted square-pyramidal environment. They are bridged by a formate group in an anti–syn configuration from a basal position to an axial position, while another axial position is occupied by the water oxygen atom. From magnetic susceptibility measurements at room temperature, both complexes are found to exhibit antiferromagnetic interactions and some magneto-structural trends are discussed.

Synthesis, spectroscopic characterisation and X-ray crystal structures of acetato(di-2-pyridylamine)nitritocopper(II) monohydrate and (di-2-pyridylamine)dinitritocopper(II)

Abstract The crystal and molecular structures of the complexes [Cu(dpyam) (O 2 CCH 3 )(NO 2 )].H 2 O (I) and [Cu(dpyam)(NO 2 ) 2 ] (II), dpyam=di-2-pyridylamine, have been determined. Both complexes consist of neutral mononuclear units, the copper(II) environments in (I) and (II) are best described as tetrahedral-distorted octahedral with elongated axial positions (4+2). The equatorial plane in (I) comprises the two dpyam nitrogen atoms at 1.997(2) and 1.963(2) A, and two oxygen atoms of two oxyanions (acetate and nitrite anions) at 2.039(2) and 1.967(2) A, with the axial positions occupied by another two oxygen atoms of the acetate and nitrite anions at the longer Cu–O distances of 2.484(2) and 2.436(2) A. The equatorial plane in (II) is composed of the two dpyam nitrogen atoms at 1.986(1) and 1.966(1) A, and two oxygen atoms of each acetate group at 2.017(1) and 2.003(1) A, with the apical positions filled by the second oxygen atoms of each nitrite group at the longer Cu–O distances of 2.469(2) and 2.431(2) A.

Structure and characterization of hexakis(imidazole) cobalt(II) complexes: [Co(Im)6(OBz)2] and [Co(Im)6(mB)2] (Im = imidazole, OBz = benzoate, mB = p-methoxybenzoate)

AbstractThe crystal and molecular structures of the complexes of [Co(Im)6(OBz)2] and [Co(Im)6(mB)2] (Im = imidazole, OBz = benzoate, mB = p-methoxybenzoate) have been determined by X-ray crystallography. The crystal structures are very similar and consist of discrete molecules of [Co(Im)6(OBz)2] and [Co(Im)6(mB)2], respectively. They both crystallize in the triclinic system, space group n

Crystal Structure Investigations of Inclusion Complexes Between β-cyclodextrin and Alkyl(aqua)cobaloximes (Alkyl=Butyl, Hexyl and Cyclohexyl)

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