Preparation and Characterization of Halogen-Boron-Phosphorus Compounds. X-ray Crystal Structures of X(3)B.P(SiMe(3))(3) and [X(2)BP(SiMe(3))(2)](2) (X = Cl, Br).
The 1:1 mole ratio reactions of boron trihalides (BX(3)) with tris(trimethylsilyl)phosphine [P(SiMe(3))(3)] produced 1:1 Lewis acid/base adducts [X(3)B.P(SiMe(3))(3), X = Cl (1), Br (2), I (5)]. Analogous 1:1 mole ratio reactions of these boron trihalides with lithium bis(trimethylsilyl)phosphide [LiP(SiMe(3))(2)] produced dimeric boron-phosphorus ring compounds {[X(2)BP(SiMe(3))(2)](2), X = Br (3), Cl (4)}. X-ray crystallographic studies were successfully conducted on compounds 1-4. Compound 1 crystallized in the orthorhombic space group Pbca, with a = 13.420(3) Å, b = 17.044(5) Å, c = 21.731(7) Å, V = 4970.6(25) Å(3), and D(calc) = 1.229 g cm(-3) for Z = 8; the B-P bond length was 2.022(9) Å, Compound 2 crystallized in the orthorhombic space group Pbca, with a = 13.581(6) Å, b = 17.106(7) Å, c = 22.021(9) Å, V = 5116(4) Å(3), and D(calc) = 1.540 g cm(-3) for Z = 8; the B-P bond length was 2.00(2) Å. Compound 3 crystallized in the monoclinic space group P2(1)/n, with a = 9.063(5) Å, b = 16.391(8) Å, c = 9.331(4) Å, V = 1379.2(12) Å(3), and D(calc) = 1.676 g cm(-3) for Z = 2; the B-P bond length was 2.023(10) Å. Compound 4 crystallized in the monoclinic space group P2(1)/n, with a = 9.143(5) Å, b = 16.021(8) Å, c = 9.170(4) Å, V = 1342.2(11) Å(3), and D(calc) = 1.282 g cm(-3) for Z = 2; the B-P bond length was 2.025(3) Å. Thermal decomposition studies were performed on compounds 1-4, yielding colored powders with boron:phosphorus ratios greater than 1:1 and significant C and H contamination indicated by elemental analyses.
Lube
Michael S.
MS
Department of Chemistry, Venable Hall, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514.
Wells
Richard L.
RL
White
Peter S.
PS