Transition metal complexes with sulfur ligands Part CXIV1. Alkylation, substitution reactions, electrochemistry and structure of nitrosyl and carbonyl complexes with the [Mo(‘S4’)] fragment (‘S4’2− = 1,2-bis(2-mercaptophenylthio) ethane (2−))2

Abstract

Alkylation of [Mo(NO) (Cl) (‘S4’)] (1) (‘S4’2 = 1,2-bis(2-mercaptophenylthio)ethane(2−)) by R3OBF4 (R = Me, Et) yielded the mono alkyl derivatives [Mo(NO) (Cl) (R−‘S4’)]BF4 (R = Me ([2]BF4), Et ([3]BF4)). NMR spectra indicated that in both cases the isolated species contained only one diastereomer. As indicated by v(NO) frequencies, [2]BF4, and [3]BF4 exhibit a lower electron density at the molybdenum centers, and they are reduced electrochemically at less negative potentials when compared to the parent compound [Mo(NO) (Cl) (‘S4’)] (1). Replacement of the chloro ligand in [Mo(NO) (Cl) (‘S4’)] (1) by o-methylthiobenzenethiolate yielded the six-coordinate complex [Mo(NO) (SC6H4SCH3)(‘S4’)] (4), in which the CH3S group does not coordinate. When 4 was treated with HCl or PMe3, the SC6H4SCH3 ligand dissociated and the parent compound 1 or the 17-electron complex [Mo(NO) (PMe3) (‘S4’)] formed. Decarbonylation of yellow [Mo(CO)3(‘S4’)] (5) yielded [Mo(CO)(μ-‘S4’)]2 (6) as a mixture of diastereomers. A centrosymmetric diastereomer of 6 with trans-coordinated CO ligands was characterized by X-ray structure analysis. Crystal data of [Mo(CO)(μ-‘S4’)]2 ·2CH2Cl2: rhombohedral space group R3; a = 31.138(5), b = 31.138(5), c = 12.152(5), A; Z = 9; R/Rw = 6.1/6.1%. Each Mo center is surrounded by five S donors, one C atom, and the neighboring Mo center. The two enantiomeric [Mo(CO)(‘S4’)] fragments are linked to each other via an Mo = Mo double bond and two bridging thiolate donors. The thiolate donors within one metal fragment are coordinated trans to each other.