Neutral transition metal complexes with the tridentate ligand 4-(5-methyl-4-imidazolyl)-3-thiabutanoic acid. A series of isostructural octahedral compounds
作者:Elisabeth Bouwman、Jan Reedijk
DOI:10.1016/0020-1693(93)03681-y
日期:1994.1
The synthesis and spectroscopic properties of the iron, cobalt, nickel and copper complexes with the ligand 4-(5-methyl-4-imidazolyl)-3-thiabutanoic acid (abbreviated Hitba) are described. The compound Co(itba)(2) (A) crystallizes in the triclinic space group P $$($) over bar 1 with a = 7.600(1), b = 7.697(1), c = 8.2696(5) Angstrom, alpha = 86.745(8), beta = 71.321(7), gamma = 69.538(12)degrees, V = 428.5 Angstrom(3), D-x = 1.65 g/cm(3) for Z = 1. The compound Cu(itba)(2) (B) crystallizes in the triclinic group P $$($) over bar 1 with a = 7.789(3), b = 7.794(4), c = 8.138(4) Angstrom, alpha = 71.448(4), beta = 86.905(4), gamma = 67.805(4)degrees, V = 432.4 Angstrom(3), D-x = 1.66 g/cm(3) for Z = 1. In both structures the metal ion is located on the inversion centre because of symmetry considerations. The non-hydrogens were located using Fourier methods and the structures were refined by least-squares methods to residual R(w) values of 0.089 (A) and 0.050 (B). The coordination geometry of the metal ion in both compounds A and B is octahedral with the donor atoms of the two ligands in mutual irans positions. The bond distances in the cobalt compound are significantly different from those in the Jahn-Teller distorted copper compound (Co-N = 2.109(7), Cu-N = 1.986(3); Co-O = 2.065(6), Cu-O = 1.988(2); Co-S = 2.501(2), Cu-S = 2.7146(8)). The geometry of the cobalt ion can be described as a rather regular octahedron compared with the elongated octahedral copper structure. The obtained compounds M(itba)(2) are all isostructural according to their X-ray powder patterns and IR spectra, and all show remarkably strong ligand field spectra.