Preparation, Crystal Structure and Spectroscopic Properties of Dimeric [Zn(2-bromobenzoato)2(phenazone)]2 and Monomeric [Zn(2-bromobenzoato)2(thiourea)2]•2H2O

The binuclear zinc complex bis(2-bromobenzoato- O)-bis(mu(2)-2-bromobenzoato-O,O')-bis(phenazone-O) -dizinc(II) (I) and the mononuclear dihydrate bis(2-bromobenzoato- O)-bis(thiourea-S)-zinc(II) (II) have been synthesized and characterized by means of elemental analysis and spectroscopic methods (IR, H-1 and C-13 NMR, EDS). The solid state structures of both compounds were determined by single-crystal X-ray diffractometry. Compound [Zn(2-BrC6H4COO)(2)(phen)](2) (phen-phenazone) (I) crystallized as a dimeric compound with a triclinic lattice (space group P - 1), where both zinc atoms, inter-connected by two carboxylate groups, possess a distorted tetrahedral coordination environment. The crystallographic data of complex I: a = 9.9410(3) angstrom, b = 10.7309(3) angstrom, c = 12.9237(4) angstrom, alpha = 93.6004(17)degrees, beta = 92.5898(11)degrees, gamma = 116.2192(16)degrees, V = 1230.26(6) angstrom(3), Z = 1. Complex [Zn(2-BrC6H4COO)(2)(tu)(2)]center dot 2H(2)O (tu-thiourea) (II) crystallized with an orthorhombic lattice (space group Aba2) as a monomeric compound, where the coordination environment of the central zinc atom is a distorted tetrahedron. The crystallographic data of complex II are: a = 9.8595(3) angstrom, b = 19.7052(5) angstrom, c = 12.5908(3) angstrom, V = 2446.18(11) angstrom(3), Z = 4. The modes of the carboxylate binding were assigned from the IR spectra using the magnitude of the separation between the carboxylate stretches (Delta), which correlated well with the crystal structures. The computed theoretical IR spectrum agreed well with the experimental data.