Synthesis of zinc and cadmium O-alkyl thiocarbonate and dithiocarbonate complexes and a cationic zinc hydrosulfide complex

Abstract

Treatment of Zn(II) and Cd(II) hydroxide complexes of the tris(2-pyridylmethyl)amine (TPA) ligand with COS or CS 2 in protic solvents (MeOH or EtOH) resulted in [(TPA)Zn-SC(S)OCH 3]ClO 4 (1), [(TPA)Zn-SC(O)OCH 3]BF 4 (2), [(TPA)Zn-SC(O)OCH 3]ClO 4 (3), [(TPA)Zn-SC(O)OCH 2CH 3]BF 4 (4), [(TPA)Cd-SC(S)OCH 3]ClO 4 (5) and [(TPA)Cd-SC(O)OCH 3]ClO 4 (6). The molecular structures of 1, 2, 5 and 6 were determined by X-ray crystallography. Complexes 2, 3 and 4, unlike 1, 5 and 6, are easily hydrolyzed upon treatment with water in CH 3CN to give zinc hydrosulfide complexes of the form [(TPA)Zn-SH]X (X = BF 4- (7) and ClO 4- (8)), as evidenced by spectroscopic methods and the crystal structure of 7. These complexes may be prepared more directly by (a) reacting equimolar amounts of TPA, Zn(ClO 4) 2·6H 2O and Me 4NOH·5H 2O with COS in CH 3CN or (b) treating [((TPA)Zn) 2(μ-OH) 2](ClO 4) 2 with H 2S. Moreover, reactivity and density functional theory computational studies comparing the cationic hydrosulfide complexes 7 and 8 with the neutral zinc hydrosulfide complexes supported by tris(pyrazolyl)borate ligands have been conducted and subtle differences between the two types of hydrosulfide complexes have been determined. © 2012 Elsevier Inc. All rights reserved.