Thiosemicarbazones as co-ordinating agents. Part 4. Synthesis, spectroscopic characterization and X-ray structure of two cobalt(III) complexes with pyridoxal thiosemicarbazone
- 1 January 1991
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 8,p. 1951-1957
- https://doi.org/10.1039/dt9910001951
Abstract
Two pyridoxal (3-hydroxy-5-hydroxymethyl-2-methylpyridine-4-carbaldehyde) thiosemicarbazone (H2L) complexes of cobalt have been synthesised and structurally characterized by spectroscopic and X-ray diffraction methods. Crystallographic parameters: [Co(H0.5L)2]·3.5H2O 1 space group C2/c, a= 10.335(1), b= 29.026(3), c= 16.564(2)Å, β= 94.85(3)°, Z= 8, R= 0.053, R′= 0.057; [Co(HL)L]·4.5H2O 2, space group Pa= 11.195(1), b= 12.138(2), c= 11.128(1)Å, α= 103.23(3), β= 99.42(2), γ= 115.49(2)°, Z= 2, R= 0.058. In both compounds the cobalt atom is co-ordinated in a rather distorted octahedron to two molecules of pyridoxal thiosemicarbazone which are not equivalent. They are cobalt(III) complexes although the starting material was a cobalt(II) salt, differing in the H-atom positions of the pyridine nitrogen atoms. In 1 both the pyridine nitrogen atoms are ‘semiprotonated’: this is responsible for a loss of regularity in the arrangement of the water molecules. In 2 only one pyridine nitrogen atom is protonated. A. strong symmetric N H N hydrogen bond [2.685(9)Å] is present in complex 1.Keywords
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