Crystal and Molecular Structures of Novel Metal–Carbene Complexes III. Rh–Carbene Complexes and Cu Complex

Abstract

Abstract 2,3,4,5-Tetrahydro-1,6-dialkyl-3,4-trimethylene-6aλ4-thia-1,3,4,6-tetraazapentalene-2,5-dithiones (1), which contain a hypervalent sulfur atom, have been found to give novel metal–carbene complexes by treating with RhCl(PPh3)3. X-Ray investigations have revealed that the resultant complexes are novel Rh–carbene complexes: trans(P,P′)-(chloro){[3-(methylthiocarbamoyl-κN)perhydropyrimidine-1-yl-κC2](methyliminomethanethiolato-κS)}-bis(triphenylphosphine)rhodium(III) (4a) and trans(P,P′)-(chloro){(perhydropyrimidine-1,3-diyl-κC2)bis[(4-chlorophenylimino)methanethiolato-κ2SS′]}bis(triphenylphosphine)rhodium(III) (4c). In these complexes, the central sulfur atom in 1 was substituted by a Rh atom. In 4a, obtained from 1,6-dimethyl-pentalene (1a), only one of the sulfur atoms of the thioamide groups coordinates the Rh atom, while the other thioamide group coordinates Rh with the N atom. Rh is coordinated by S, N, C, and Cl atoms to form an equatorial plane, and is coordinated by two PPh3 groups axially. In 4c, obtained from the 4-chlorophenyl derivative (1c), two thioamide groups rotated to form an S–Rh–S bond. A reaction of 1a with Cu(ClO4)2 gave a different kind of complex, bis (2,3,4,5-tetrahydro-1,6-dimethyl-3,4-trimethylene-6aλ4-thia-1,3,4,6-tetraazapentalene-2,5-dithione-κ2S4)copper(I) (7). The framework of the starting tetraazathiapentalene 1 remained unsubstituted, and the sulfur atoms of the thiocarbonyl groups of 1 coordinated the Cu atom to form one-dimensional coordination polymers, where the Cu atom is coordinated tetrahedrally by four S atoms. Because of a difference in the changes of the oxidation numbers of the metals during the reactions, metal–carbene complexes could not be obtained in the case of the Cu-complex.