SYNTHETIC, SPECTROSCOPIC AND X-RAY CRYSTALLOGRAPHIC STUDIES ON COPPER(II) COMPLEXES WITH PYRUVIC-ACID AND PYRIDOXAL THIOSEMICARBAZONES

Reaction of copper sulfate with two ligands, pyridoxal 5-(hydroxymethy l)-2-methylpyridine-3-carbaldehyde] (H2L) and methylpyruvate thiosemic arbazones (Hmpt) leads to the formation of two new complexes [Cu(H2L)( OH2)(2)]SO4 . H2O (1) and [{Cu(Hpt)(OH2)}(2)SO4] (2) (H(2)pt = pyruvic acid thiosemicarbazone) which have been characterized using single-cr ystal X-ray diffraction and IR spectroscopy. Crystals of complex 1 are triclinic, space group P (1) over bar, with a = 10.885(4), b = 10.022 (4), c = 8.721(4) Angstrom, alpha = 87.38(2), beta = 72.14(3), gamma = 64.99(1)degrees and Z = 2. Compound 2 crystallizes monoclinic, space group C2/c, with a = 15.478(2), b = 17.733(2), c = 6.891(1) Angstrom, beta = 106.10(2)degrees and Z = 4. The structure of 1 consists of disc rete [Cu(H2L)(OH2)(2)](2+) cations, SO42- anions and uncoordinated wat er molecules; in complex 2 the sulfate group acts as bridging bidentat e giving rise to dimers produced by a two-fold axis. In both compounds the copper atom is coordinated in a rather distorted square pyramid. The main vibrational bands are also discussed. (C) 1998 Elsevier Scien ce S.A.