A Convenient Route to Mixed Pnictogenylboranes.

We report on the synthesis and characterization of mixed pnictogenylboranes. The substitution of the Lewis base SMe2 in (OC)5 W-PH2 BH2 -SMe2 (2) by different pnictogenylboranes ER2 BH2 -LB (E=P, As, Sb) leads to the Lewis acid/base stabilized butane analogue (OC)5 W-PH2 BH2 ER2 BH2 -LB (3 a, b: E=P; R=H, SiMe3 ; LB=NMe3 ; 4 a, b: E=As; R=H, SiMe3 ; LB=NMe3 ; 5: E=Sb; R=SiMe3 ; LB=NHCMe ). All of these compounds were characterized by single-crystal X-ray structure analysis, mass spectrometry, NMR, and IR spectroscopy. In addition, the very unstable phosphanylborane chain PH2 BH2 PH2 BH2 -NMe3 (1) was synthesized. DFT calculations provide insight into the thermodynamics of these reactions.