Metal dithiocarbamates and related species. Part 2. Reaction of zinc thiuram disulphides with triphenylphosphine and other Lewis bases, and anionic dithiocarbamato-complexes of zinc

Abstract

Reaction of [ZnI₂{(S₂CNMe₂)₂}] with 1, 2, and 3 mol of PPh₃ gives [ZnI₂{S(SCNMe₂)₂}], [PPh₃{C(NMe₂)S}][ZnI₂(S₂CNMe₂)], and [PPh₃{C(NMe₂)S}][ZnI₃(PPh₃)], respectively, together with PPh₃S and small amounts of [ZnI₂(PPh₂)₂]. These reactions can be carried out in steps, and the identity of the products has been confirmed by independent synthesis and spectral methods. The species [ZnX₂{S(SCNMe₂)₂}](X = Cl or Br), [NBuⁿ₄]ZnX₂(S₂CNMe₂)](X = Cl, Br, or I), and [PPh₃{C(NMe₂)S}]X (X = PF₆ or I) have been prepared. The cation [PPh₃{C(NMe₂)S}]⁺ reacts with [S₂CNMe₂]^– giving S(SCNMe₂)₂ and PPh₃. Treatment of [Zn(S₂CNRR′)₂] with [S₂CNRR′]^– affords [Zn(S₂CNRR′)₃]^–(R = R′= Me; R = Me, R′= Ph; isolated as [NEt₄]⁺ or [NBuⁿ₄⁺ salts), while [Zn(S₂CNR₂)₂](R = Et or Buⁿ) react with [S₂CNMe₂]^– affording [Zn(S₂CNEt₂)₂(S₂CNMe₂)]^– or [Zn(S₂CNBuⁿ₂)(S₂CNMe₂)₂]^–, respectively. Treatment of [Zn(S₂CNMe₂)₂] with [NBuⁿ₄][O₂CMe] afforded [NBuⁿ₄][Zn(O₂CMe)(S₂CNMe₂)₂]. Possiblemechanismsfortheattackof PPh₃ on metal-co-ordinated (R₂NCS₂)₂ and S(SCNR₂)₂ are discussed, and brief comments are made on the relation of species such as [Zn(O₂CR′)(S₂CNR₂)₂]^– to the acceleration of vulcanisation of natural rubber.