Two isomorphous ZnII/CoII complexes with tri-tert-butoxysilanethiol and histamine, and (4-hydroxymethyl-1H-imidazole-kappaN)bis(tri-tert-butoxysilanethiolato-kappa2O,S)zinc(II)

Abstract

The complexes [2-(1H-imidazol-4-yl-kappaN(3))ethylamine-kappaN]bis(tri-tert-butoxysilanethiolato-kappaS)cobalt(II), [Co(C(12)H(27)O(3)SSi)(2)(C(5)H(9)N(3))], and [2-(1H-imidazol-4-yl-kappaN(3))ethylamine-kappaN]bis(tri-tert-butoxysilanethiolato-kappaS)zinc(II), [Zn(C(12)H(27)O(3)SSi)(2)(C(5)H(9)N(3))], are isomorphous. The central Zn(II)/Co(II) ions are surrounded by two S atoms from the tri-tert-butoxysilanethiolate ligand and by two N atoms from the chelating histamine ligand in a distorted tetrahedral geometry, with two intramolecular N-H...O hydrogen-bonding interactions between the histamine NH(2) groups and tert-butoxy O atoms. Molecules of the complexes are joined into dimers via two intermolecular bifurcated N-H...(S,O) hydrogen bonds. The Zn(II) atom in [(1H-imidazol-4-yl-kappaN(3))methanol]bis(tri-tert-butoxysilanethiolato-kappa(2)O,S)zinc(II), [Zn(C(12)H(27)O(3)SSi)(2)(C(4)H(6)N(2)O)], is five-coordinated by two O and two S atoms from the O,S-chelating silanethiolate ligand and by one N atom from (1H-imidazol-4-yl)methanol; the hydroxy group forms an intramolecular hydrogen bond with sulfur. Molecules of this complex pack as zigzag chains linked by N-H...O hydrogen bonds. These structures provide reference details for cysteine- and histidine-ligated metal centers in proteins.