Cationic ruthenium-sulfine complexes: Synthesis and dynamic behaviour [1]

Cationic ruthenium sulfine complexes [CpRu(PR'(3))(2)(O=S=CHR)]PF6 have been obtained by a variety of methods. Oxidation of the thioaldehyde complexes [CpRu(PR'(3))(2)(S=CHR)]PF6 with either 2-tosyl-3-phenyl-oxaziridine (PR'(3) = PMe3) or magnesium-monoperoxyphthalate (PR'(3) = (1)/(2) dppm) gave complexes of arylsulfines (R = Ph, 3-C6H4F, 4-C6H4Cl, 4-C6H4OMe) selectively in their thermodynamically less stable E form. Siloxane elimination from the suffinato complexes [CpRu(PMe3)(2)(SO2CHRSiMe3)] yielded complexes of aliphatic sulfines, [CpRu(PMe3)(2)(O=S=CHR)]PF6 (R = H, Me). Treatment of [CpRu(dppm)(SO2CH2R)] with acetyl chloride led to an oxygen redistribution giving complexes of thioaldehydes [CpRu(dppm)(eta(2)-S=CH2)]PF6 and [CpRu(dppm)(eta(1)-S=CHR)]PF6 (R = Ph, 4-C6H4Cl). The structure of the latter was determined by X-ray crystallography. The loss of oxygen can be suppressed by performing the acylation-elimination sequence in the presence of poly-(4-vinylpyridine). This provided a selective access to complexes of Z-sulfines, [CpRu(PMe3)(2)(O=S=CHR)]PF6 (R = Ph, 4-C6H4Cl) and [CpRu(dppm)(O=S=CHR)]PF6 (R = Ph, 4-C6H4Cl, COOEt, Cl). Complexes of the parent sulfine O=S=CH2 were also obtained by SO transfer to the methylene complex [CpRu(PMe3)(2)(CH2)]PF6 and methylene transfer to the sulfur monoxide complex [Cp*Ru(PMe3)(2) (SO)]PF6. Most of the new sulfine complexes exhibit dynamic behaviour in solution, i.e. ligand rotation, ligand inversion, and eta(2)/eta(up arrow) hapticity change. O-Alkylation provided the dicationic complex [CpRu(PMe3)(2) (EtO-S=CHMe)](PF6)(2), and S-oxidation gave the sulfene complexes [(C5R5)Ru(PMe3)(2) (O2S=CH2)]PF6 (R = H, Me).