A Bicyclic P–P‐Bridged 1,3,2,4‐Diphosphadiboretane Cation and an Imino(phosphinidene)borane–AlBr3 Adduct

Abstract

AbstractDepending on reaction conditions the 1,3,2,4‐diphosphadiboretane 1 reacts with AlBr3 to give the unstable adduct tmp=B=P(tBu)AlBr3, 3, and/or the somewhat more stable salt [(tmpB)2(PtBu)P]+[AlBr4], 2. The X‐ray structure determination of 3 shows an almost linear NBP array with BN and BP double bonds resembling an allene type structure. NBO analysis shows the presence of BN‐ and BP‐π‐bonds. On the other hand, the cation of compound 2 has a bicyclic structure with a long P–P bond [2.349(2) Å]. The B–P bonds to the phosphonium type P2 atom [av. 1.939(5) Å] are longer than those to the tri‐coordinated P1 atom [1.889(6) Å]. NBO analysis of the model compound (H2NB)2(PMe)P+, 9, show that the P–P bond in 2 is formed from p‐orbitals.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)