Chirantan Roy Choudhury

First report of singly phenoxo-bridged copper(II) dimeric complexes: synthesis, crystal structure and low-temperature magnetic behaviour study

Three singly phenoxo-bridged dinuclear Cu(II) complexes [Cu2(L)2(SCN)(H2O)](ClO4) 1, [Cu2(L)2(N3)(H2O)](ClO4) 2, [Cu2(L)2(NCO)(H2O)](ClO4) 3 (HL is the Schiff base ligand derived from O-vanillin and 2-aminomethyl ethylenediamine) have been synthesised and characterised by infrared, UV-Vis spectra, electrochemical study and single crystal X-ray diffraction study. In all the complexes (1–3), there are two geometrically different square pyramidal copper(II) centres, with N3O2 and N2O3 donor sets for the two Cu(II) centres. In the dimeric unit, the copper atoms are held together by only one distinct rare μ2-phenolate oxygen of one Schiff base. The Cu–Cu distances are 3.291(2), 3.244(1) and 3.244(1) A for complexes 1, 2 and 3, respectively, and the Cu–O–Cu angles are found to be 111.5(1), 109.3(2), 109.6(1)° for complexes 1, 2 and 3, respectively. Variable temperature magnetic susceptibility study on the complexes 1,2 and 3 indicate the presence of antiferromagnetic coupling between the Cu(II) centres with 2J values −109.8, −103.9 and −95.9 cm−1, respectively.

A novel doubly phenoxo-bridged Cu(II) trimer: synthesis, crystal structure and low-temperature magnetic behaviour

A novel doubly phenoxo-bridged Cu(II) trimeric complex, [trinuclear diperchlorato {2,2′-[1,3-propanediylbis (nitriloethylidyne)]bisphenolato}-tricopper] has been synthesised with a tetradentate Schiff base ligand and characterised by IR, electronic spectra, X-ray structure and variable temperature magnetic moments. The Cu1 centre has square pyramidal geometry where as the Cu2 centre achieves square planar geometry. The dihedral angle between the two planes, Cu1 – O1 – O2 and Cu2 – O1 – O2 is 26.50°.

Synthesis and structural characterization of [Ni(Me2NCH2CH2CH2N=CHC6H4O)2]

The synthesis, properties, and X-ray crystal structure of a Ni(II) complex of the tridentate Schiff base ligand Me2NCH2CH2CH2N=CHC6H4OH(LH) are described. The complex crystallizes in the monoclinic space group P21/c, with a = 10.180(2), b = 15.169(3), c = 15.293(4) Å, β = 106.69(2)°, and Z = 4. The Ni atom shows a distorted fac-octahedral geometry, with the two Ni—N(Me2) bonds being significantly longer than the two Ni—N(imino) bonds, 2.284(9), 2.310(9) vs. 2.051(2), 2.055(2) Å.

Two novel Zn(II) helical chain polymers containing both bridging and terminal carboxylato groups

Abstract Two novel carboxylato-bridged Zn(II) polymeric complexes [Zn(L)(CCl3COO)]n and [Zn(L)(CF3COO)]n, where [L=2-N-(2′-pyridylimine)benzoic acid] have been synthesized and structurally characterized. The structures of the two complexes are similar with the Zn(L)(Cl3CCO2) or Zn(L)(F3CCO2) units being repeated to form infinite helical chains. In each structure, the neighbouring Zn atoms are bridged sequentially by syn–anti carboxylate groups of the Schiff base.

Synthesis and structural studies of selenocyanato-bridged polymeric and molecular complexes of cadmium(II): presence of both end-to-end and end-on coordination

Abstract Two new complexes, having one two-dimensional zig–zag polymeric network [Cd2(dmen)2(SeCN)4]n (1) and one molecular packing structure [Cd(dmen)2(SeCN)2] (2) (where dmen=N,N-dimethyl ethylenediamine), have been synthesised and characterised by infrared spectra and single crystal X-ray diffraction study. The different arrangements of selenocyanate anions result in two dimensional zig–zag polymeric sheet with the formation of two different rings, one having an eight-membered nearly hexagonal ring and another having a pseudo 16-membered ring for 1 and a molecular complex 2 with four independent molecules, having a total of 16 molecules per cell. The coordination environment in both the complexes is distorted octahedral. In the selenocyanato-bridged polymeric complex the cadmium(II) ions are linked by end-to-end coordination whereas in the molecular complex the cadmium(II) ions are bridged by end-on coordination only.

Two New Quadridentate Schiff Base Complexes of Nickel(II) and Cobalt(III): Synthesis, Structure and Spectral Characterisation

Two novel quadridentate Schiff base complexes, [NiIILH](ClO4)2・H2O (1) and [CoIIIL]- (ClO4)2・H2O (2) [LH, a Schiff base ligand: Ph(OH)C(Me)=NCH2CH2N(CH2CH2NH2)2] have been synthesised and characterised by elemental analyses, spectroscopic and electrochemical studies. The structures of both have been unequivocally established from single crystal X-ray diffraction studies. 1 and 2 crystallise in the monoclinic space group P21/n having cell parameters a = 8.536(1), b = 13.832(4), c = 18.194(2) Å , β = 100.00(10)°, Z = 4 for 1, and a = 10.819(5), b = 14.301(2), c=14.224(1) Å , β =97.04(2)°, Z =4 for 2. The complexes expose a square planar geometry around the metal centers chelated with three different types of nitrogen donor centers of the ligand.

A new cyanato-bridged polymeric complex [Cd3(NCO)6(NH2CH2C5H4N)3]n with a zig–zag ladder shaped structure

Abstract A new cyanato-bridged polymeric complex [Cd3(NCO)6(NH2CH2C5H4N)3]n has been synthesized and characterized by X-ray crystallography. There are three cadmium atoms, three chelated 2-(aminomethyl)pyridine and six end-on bridging cyanato groups in the asymmetric unit. Each Cd atom is bonded to one chelated C5H4NCH2NH2 base and four μ2-NCO groups in a distorted octahedral environment. Three such independent CdN6 octahedra share their bridging edges to produce a zig–zag ladder shaped polymeric network extending along a.

Synthesis and the crystal structure of a copper(II) complex dervied from novel tridentate ligand: An unexpected one

A novel tridentate ligand C5H4NCONHCOC5H4N (HL) has been formed by Cannizzaro type reaction of pyridine-2-carboxaldehyde and NaNCO in the presence of copper metal ion and its mononuclear distorted square pyramidal complex [Cu(L)(NCO)(H2O)], 1 has been synthesised and characterised.

Two new Mn(II) and Co(II) complexes with the tridentate 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand

Two new complexes of manganese(II) and cobalt(II), [Mn(tptz)(OCH3CO)(H2O)2]ClO4 (1) and [Co(tptz) (OSO3) (H2O)2](H2O)2 (2) {where tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine}, have been prepared and characterised by elemental analyses, spectroscopic, electrochemical studies and single crystal X-ray diffraction. Single crystal X-ray analysis reveals complexes of Mn(II) and Co(II), where tptz remains intact and behaves as a tridentate ligand and forms heptacoordinated Mn(II) and hexacoordinated Co(II) complexes for 1 and 2, respectively.

Isolation and characterisation of a novel thermally stable octahedral bicarbonato complex of bis(2-picolylamine)copper(II): identification of rare monodentate coordination

A novel bicarbonate complex, [Cu(C5H4NCH2NH2)2(OCO2H)2] (1), has been synthesised under controlled pH and characterised by IR, UV-Vis spectroscopy, magnetic moment and thermal analysis; the coordination environment around the metal centre is elongated octahedral with two chelated bidentate amines in the square plane and the axial sites are occupied by two monodentate bicarbonate ligands.