Reactivity of rhenium(I) pseudo-allyl complexes with heterocumulenes such as RNCS (R = Me or Ph, p-MeC6H4) and PhNCO. Part 1. Crystal structure determination of two isostructural monothio- and dithio-carbamate rhenium(I) complexes co-crystallized as [Re(CO)2(PPh3)2{SC(NHPh)–S}]·[Re(CO)2(PPh3)2{O–C(NHPh)S}]

Abstract

The compounds [Re(CO)₂(PPh₃)₂(OCHNC₆H₄Me-p)] and [Re(CO)₂(PPh₃)₂(amt)][amt = anion of 2-(aminomethyl)thiazole] react with an excess of PhNCO under non-anhydrous conditions to give the displacement of the starting chelate ligand and the formation of the carbamate complex [Re(CO)₂(PPh₃)₂{OC(NHPh)O}]. When the reaction is carried out under the same conditions with an excess of RNCS (R = Ph or p-MeC₆H₄) the monothio- and dithio-carbamate complexes [Re(CO)₂(PPh₃)₂{O–C(NHR)S}](1) and [Re(CO)₂(PPh₃)₂{SC(NHR)–S}](2) are obtained. The formation of complexes (2) proceeds via the intermediate formation of (1). A mixture of complexes (1b) and (2b)(R = Ph) gives rise to a crystallized compound, which X-ray analysis has allowed to be formulated as [Re(CO)₂(PPh₃)₂{SC(NHPh)S}]·[Re(CO)₂(PPh₃)₂{OC(NHPh)S}] where discrete molecules of two isostructural rhenium complexes are co-crystallized in the monoclinic cell, of space group P2₁, with a= 9.314(6), b= 22.976(4)c= 18.662(5)Å, and β= 91.01(3)°. In both molecules the Re is six-co-ordinate in a distorted octahedral environment with trans PPh₃ groups, cis CO groups, and one bidentate ligand. Distances in the co-ordination sphere are: Re–P 2.42 (mean), Re–C 1.90 (mean), Re–S 2.52 (mean), and Re–O 2.37 Å. The ligand moieties are essentially planar in both complexes.