Synthesis and spectroscopic studies of cobalt(III) complexes with 5-methyl-3-formylpyrazole-N(4)-diethylthiosemicarbazone (HMPzNEt2): X-ray crystallography of [Co(MPzNEt2)2]ClO4·2H2O (I) and [Co(MPzNEt2)2]BF4·2H2O (II)
摘要:
The co-ordination mode of the title ligand, HMP2NEt2 (synthesised for the first time and characterised by elemental analyses, mass, IR and H-1 NMR spectral parameters), is reported by solid state isolation and physico-chemical identification of cobalt(III) complexes, [Co(MPzNEt2)(2)]X.2H(2)O (X=Cl, Br, ClO4, BF4, and NO3). Electronic spectral features of these diamagnetic Co(III) species classify them as six co-ordinate distorted octahedral ones. IR spectra (4000-200 cm(-1)) indicate that the Co(III) complexes have monoanionic tridentate NNS co-ordination of the title ligand through the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulfur atoms. H-1 NMR data (in CDCl3 at 300 MHz) for the uncomplexed ligand and those of its Co(III) complexes are commensurate with the NNS function of the monodeprotonated HMPzNEt2, as ascertained from downfield shift of the relevant protons adjacent to the bonding sites. X-ray crystallographic data of I and II (both P (1) over bar, triclinic) have authenticated a CoN4S2 octahedral co-ordination in both the complex ions. (C) 2002 Elsevier Science Ltd. All rights reserved.