Reactivity of Disulfidodicopper(II) Complexes and Its Theoretical Study by DFT Calculation

Abstract

Previously, the reactions of three µ-η 2 :η 2 -disulfidodicopper(II) complexes with N-alkylated cis,cis-1,3,5-triaminocyclohexane derivatives, [Cu 2 (S 2 )(R 3 TACH)]X 2 [(R, X) = (Et, CF 3 SO 3 ) (1), (iBu, SbF 6 ) (2), and (Bn, SbF 6 ) (3)], with PPh 3 and BnBr were reported. In order to clarify the relationship between the structures and reactivities, DFT calculations of the two complexes with bent and planar Cu 2 S 2 structures have been performed, and the bond orders around the metals and atomic charges on Cu and S atoms have been estimated. The electron density is localized on Cu and S atoms when the dihedral angle (δ) is decreased; 1.137 and −0.470 for the bent type structure (δ = 156.67 ˚) and 1.107 and −0.450 for the planar one (δ = 175.56 ˚), respectively. The reactivity of disulfidodicopper(II) complexes against PPh 3 has been explained to depend upon the electrophilicity of Cu atoms and the nucleophilicity of S atoms, which are raised up by bending of two CuS 2 planes. These findings show that the disulfides of 1, 2, and 3 are electrophilic against exogenous substrates.

Synthesis and Reactivity of µ-η2:η2-Disulfido Dicopper(II) Complex with N,N ',N''-Trimethyl-1,3,5-cis,cis-triaminocyclohexane

“…The bands at 353 and 462 nm were assigned to the charge transfer (CT) transition from the in-plane disulfido à to copper(II) ion, and the band at 397 nm was assigned to the CT transition from the disulfido à to copper(II) ion. 12) These three CT bands are characteristic for a disulfido dicopper(II) complex. Judging from the X-ray structures of complexes 2, 3, and 4 that gave the same UV-vis spectrum as 1, the compound 1 is considered to form a -2 : 2 -disulfido dicopper(II) complex.…”

“…1), and proposed that their reactivities toward triphenylphosphine (PPh 3 ) are related by the dihedral angles between two planes defined by the CuS 2 plane. 11,12) In this study, we synthesized a new -2 : 2 -disulfido dicopper(II) complex with N,N 0 ,N 00 -trimethyl-1,3,5-cis,cis-triaminocyclohexane (Me 3 TACH) (1) and discussed the reactivity through the comparison with those of disulfido dicopper(II) complexes with R 3 TACH previously reported. 11)…”