A preparative and multinuclear nuclear magnetic resonance spectroscopic study of As(SPh)x(SePh)3−x(x = 0−3), Sb(SPh)x(SePh)3−x (x = 0−3), Bi(SPh)3, Bi(SePh)3, [Sn(SPh)x(SePh)3−x]−(x = 0−3), Pb(SePh)3−, and Pb(SPh)3− and some related thiolatoplumbates(II)

Abstract

The phenyl selenolates of tin(II), lead(II), arsenic(III), antimony(III), and bismuth(III), M(SePh)n (M = Sn(II) or Pb(II), n = 2; M = As(III), Sb(III), or Bi(III), n = 3), have been synthesized by acid–base reaction of the appropriate metal acetate (for M = Sn(II) or Pb(II)) or thiophenolate (for all five elements) with PhSeH, and characterized by elemental analysis and, for the Group V elements, 77Se and 13C nmr spectroscopy.M(SPh)2 and M(SePh)2 (M = Sn(II) or Pb(II)) are poorly soluble in MeOH but dissolve in the presence of an equimolar or greater amount of PhS− or PhSe−. The soluble stannate(II) complexes are triligated as shown by the slow exchange 119Sn and, where appropriate, 77Se nmr spectra of the series [Sn(SPh)x(SePh)3−x]− (x = 0−3) measured for the supernatant liquor of mixtures in which {Sn(EPh)2}total/PhE−total > I. The corresponding plumbate(II) complexes are probably triligated also, but are labile on the nmr timescale; the parent complexes Pb(Eph)3− have been characterized in solution by 207Pb and 13C (E = S and Se) and 77Se (E = Se) nmr spectroscopy. For both Pb(II) and Sn(II), the order of chemical shifts in the metal nmr spectra is δ(MSe3) > 5(MS3). The metal nmr spectra of the mixtures M(SePh)2:PhSe−:PhS− ≈ 1:2:4 (M = Sn(II) or Pb(II)) show that the coordination of PhSe− occurs in preference to coordination of PhS− for both tin(II) and lead(II).Thiolatoplumbates(II) might be formed during some antidotal treatments for lead poisoning, so "fingerprint" 207Pb nmr spectra have been measured for a range of model soluble species formed in Pb(SR)2−(excess)RS− mixtures in MeOH, including some mixtures containing newly synthesized and characterized lead thiolates derived from dithiolate anions. For RS− = MeS−, EtS−, PhS−, C6H11S− (for which "Pb(SR)2" has been shown to be Pb(SC6H11)(OAc)),−S(CH2)2S−/2, −SCH2CHS−Me/2, and −SCH2CHS−CH2OH2, δPb (from PbMe4 in toluene as reference) falls in the comparatively short range 2518–2999 ppm.The redistribution of ligands between M(SPh)3 and M(SePh)3 in chloroform to give equilibrium mixtures of M(SPh)x(SePh)3−x, occurs slowly on the preparative timescale for M = As, rapidly on the preparative timescale but slowly on the 13C and 77Se nmr timescales for M = Sb, and rapidly on the 13C and 77Se nmr timescales for M = Bi. Thus 13C and, where appropriate, 77Se nmr data are reported for M(SPh)x(SePh)3−x (M = As or Sb) and Bi(EPh)3 (E = S or Se). In addition, it has been possible, using 13C nmr assessment of species distribution in the systems Sb(SPh)3–As(SePh)3 and Bi(SPh)3–As(SePh)3, to deduce that for the trivalent Group V elements the order of preference for PhSe− over PhS− as ligands is Bi > Sb > As.Trends in the 13C nmr data for M(SPh)x(SePh)3−x (M = As or Sb) and 77Se nmr data for a range of metal complexes of PhSe− have been discussed. The selenium chemical shifts are influenced primarily by the acceptor atom and are in the order Cd(II) < Zn(II) < Pb(II) < Sn(II) < As(III) < Bi(III) < Sb(III).