Synthesis and Chemistry of Bis(borylphosphino)silanes and -germanes

The reactions of Me(2)SiCl(2), Ph(2)SiCl(2), and Ph(2)GeCl(2) with LiP(H)B(N(i)Pr(2))(2) in a 1:2 ratio and the reaction of Ph(2)SiCl(2) with LiP(H)B(N(i)Pr(2))[N(SiMe(3))(2)] in a 1:2 ratio give good yields of the respective diphosphinosilanes, Me(2)Si[P(H)B(N(i)Pr(2))(2)](2), Ph(2)Si[P(H)B(N(i)Pr(2))(2)](2), Ph(2)Ge[P(H)B(N(i)Pr(2))(2)](2), and Ph(2)Si[P(H)B(N(i)Pr(2))[N(SiMe(3))(2)]](2). These species, when combined with BuLi in a 1:2 ratio, give lithium diphosphinosilanes and -germanes of the general type (DME.Li)(2){[PB(NR(2))(2)](2)ER'(2)}. All of the species have been characterized by spectroscopic methods. The molecular structures of three of the lithio compounds, (DME.Li)(2){[PB(N(i)Pr(2))(2)](2)SiPh(2)} (11), (DME.Li)(2){[PB(N(i)Pr(2))N(SiMe(3))(2)](2)SiPh(2)} (15), and (DME.Li)(2){[PB(N(i)Pr(2))(2)](2)GePh(2)} (13), have been determined by X-ray diffraction techniques. 11 crystallized in the triclinic space group P&onemacr; with a = 11.071(2) Å, b = 14.937(3) Å, c = 18.080(4) Å, alpha = 91.31(3) degrees, beta = 101.23(3) degrees, gamma = 109.95(3) degrees, and Z = 2, and 13 crystallized in the triclinic space group P&onemacr; with a = 11.083(1) Å, b = 14.978(2) Å, c = 18.134(2) Å, alpha = 91.17(1) degrees, beta = 101.43(1) degrees, gamma = 110.05(1) degrees, and Z = 2. 15 crystallized in the monoclinic space group P2(1)/n with a = 11.939(2) Å, b = 24.516(3) Å, c = 21.572(3) Å, beta = 101.52(1) degrees, and Z = 4. The reactions of the lithio compounds were surveyed with R(2)ECl(2) reagents. The metathesis reactions are sluggish, but the 1:1 reaction of (DME.Li)(2){[PB(N(i)Pr(2))(2)](2)GePh(2)} with (t)Bu(2)SnCl(2) gave the four-membered-ring compound The 1:2 reaction of Me(2)(Cl)SiSi(Cl)Me(2) with LiP(H)B(N(i)Pr(2))(2) yielded the (borylphosphino)silane [Me(2)SiP(H)B(N(i)Pr(2))(2)](2).