Improved synthesis of the radical source bis[2,2,6,6-tetramethylpiperidyl-(1)]-disulfide and photoinduced reactions with M-2(CO)(10) (M = Mn, Re)

An improved synthesis of bis[2,2,6,6-tetramethylpiperidyl-(1)]-disulfide (( tmps)(2)) in moderate yield is reported. Reaction of N-(trimethylsilyl)- im idazole with S2Cl2 gives N,N'-dithiobisimidazole and trimethylsilylchloride . The disulfide undergoes exchange of the heterocycle wth 2,2,6,6-tetrameth ylpiperidine and yields bis[2.2,6.6-tetramethylpiperidyl-( 1)]-disulfide an d imidazole. This synthesis offers the advantage that only traces of the bi s[2,2,6,6-tetramethylpiperidyl-(1)]-trisulfide are produced. The synthesis and spectroscopic properties of the dimeric compounds [M(CO)(4)tmps] (2) (M = Mn, Re) obtained by UV irradiation of a mixture of (tmps)(2) with M-2(CO )(10) (M = Mn, Re) is described. (C) 2001 Elsevier Science B.V. All rights reserved.