Preparation and structure of 1,4-dichloro-1,1,3,3-tetraphenyl-catena-di-(boraphosphane), BH2Cl·PPh2·BH2·PPh2Cl

Abstract

The title compound has been isolated as an unexpected product of the reaction between [NMe₄][B₃H₈] and PPh₂Cl, and has been examined by ¹H, ³¹P, and ¹¹B n.m.r. spectroscopy and by single-crystal X-ray analysis. The compound crystallizes in colourless prisms in the triclinic space group P with a= 12.15(5), b= 12.151(7), c= 9.523(4)Å, α= 92.60(4), β= 103.48(3), γ= 116.33(4)°, U= 1 207.4(9)ų, and Z= 2. The structure has been solved using diffractometer data on 2 028 independent reflections; all the atoms have been included in the refinement which gives a final R of 0.043 and R′of 0.053. Interatomic distances along the chain are Cl(1)–B(1) 1.877(7), B(l)–P(2) 1.953(6), P(2)–B(3) 1.959(6), B(3)–P(4) 1.907(6), and P(4)–Cl(4) 2.025(2)Å. The angles Cl(1)–B(1)–P(2) 110.1(3), B(1)–P(2)–B(3) 113.6(3), P(2)–B(3)–P(4) 117.1(2), and B(3)–P(4)–Cl(4) 113.5(2)° are all somewhat larger than tetrahedral, presumably due to non-bonded steric interaction.