Aspects of the inorganic chemistry of rubber vulcanisation. Part 4. Dialkyl- and diaryl-dithiophosphate and -dithiophosphinate complexes of zinc: phosphorus-31 nuclear magnetic resonance spectral studies and structures of [NMe4][Zn{S2P(OC6H4Me-p)2}3] and [NEt4][Zn(S2PPh2)3]
Abstract
The complexes [NMe4][Zn{S2P(OC6H4Me-p)2}3] and [NEt4][Zn(S2PPh2)3] have been prepared by treatment of [Zn(S2PR2)2] with [NR′4][S2PR2](R = OC6H4Me-p or Ph, R′= Me or Et). Preparation of [Znl2{S2P(OPri)2}]– and [Zn(S2PR2)2(S2CNMe2)]–(R = OC6H4Me-p or Ph) is also described. From reactions of [Zn{S2P(OR)2}2](R = Pri or C6H4Me-p) with H2O2 or ButO(OH), zinc phosphates and ZnSO4 have been obtained, and [Zn{S2P(OPh)2}2] and [Zn{S2P(OPh)2}3]– react with ROH (R = Et or Pri) in solution to give amongst other products [Zn{S2P(OR)2}2] and [S2P(OR)2]– with loss of phenol. The 31P n.m.r. spectra of a series of dialkyl- and diaryl-dithiophosphate and -phosphinate complexes have been recorded and used to establish rapid exchange within the equilibrium [Zn{S2P(OR)2}3]–⇌[Zn{S2P(OR)2}2]+[S2P(OR)2]–. The structures of the title compounds have been determined crystallographically: [NMe4][Zn{S2P(OC6H4Me-p)2}3] is monoclinic with a= 29.311(9), b= 11.032(3), c= 17.515(5)Å, β= 106.83(2)°, space group P21/a, Z= 4, and 2 490 reflections give R 0.0532; [NEt4][Zn(S2PPh2)3] is monoclinic with a= 11.160(6), b= 9.962(5), c= 43.11(3)Å, β= 104.73(5)°, space group P21/c, Z= 4, and 3 304 reflections give R 0.0411. Both have slightly distorted tetrahedral geometries in which one S2PR2 ligand is bidentate, and the other two are unidentate.
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