Stereochemical Consequences of the Bismuth Atom Electron Lone Pair, a Comparison between MX(6)E and MX(6) Systems. Crystal and Molecular Structures of Tris[N-(P,P-diphenylphosphinoyl)-P,P-diphenylphosphinimidato]bismuth(III), [Bi{(OPPh(2))(2)N}(3)], -indium(III), [In{(OPPh(2))(2)N}(3)].C(6)H(6), and -gallium(III), [Ga{(OPPh(2))(2)N}(3)].CH(2)Cl(2).

The tetraphenylimidodiphosphinate [N-(P,P-diphenylphosphinoyl)-P,P-diphenylphosphinimidate] ion forms stable tris-chelates with the Bi(III), In(III), and Ga(III) cations. The crystal and molecular structures of [M{(OPPh(2))(2)N}(3)] (M = Ga, In, Bi) were determined by X-ray diffractometry. The geometry around the bismuth atom in compound 3 displays an approximately C(3)(v)() symmetry. This arrangement suggests the presence of a stereoactive lone pair of electrons, which is located in one of the triangular octahedral faces. Derivative 3 crystallizes in the triclinic space group P&onemacr; with Z = 2, a = 14.006(6) Å, b = 14.185(4) Å, c = 17.609(8) Å, alpha = 88.45(2) degrees, beta = 79.34(2) degrees, and gamma = 78.23(2) degrees. The structures of the gallium(III) and indium(III) tris-chelate oxygen-based complexes (1 and 2, respectively) were compared with the bismuth analogue in order to determine the ligand steric bulk influence on the coordination sphere in the absence of the electron lone pair. Complex 1 crystallizes as the [Ga{(OPPh(2))(2)N}(3)].CH(2)Cl(2) solvate in the triclinic space group P&onemacr;; Z = 2, a = 13.534(4) Å, b = 13.855(4) Å, c = 18.732(7) Å, alpha = 95.48(2) degrees, beta = 98.26(2) degrees, and gamma = 97.84(2) degrees. Crystal data for the benzene solvate of 2, [In{(OPPh(2))(2)N}(3)].C(6)H(6): triclinic space group P&onemacr;, Z = 2, a = 13.542(9) Å, b = 15.622(3) Å, c = 18.063(5) Å, alpha = 98.21(1) degrees, beta = 104.77(0) degrees, and gamma = 92.260(0) degrees.