Bidentate Phosphanyl- and Arsanylboranes.

A new class of neutral bidentate ligands with pnictogenyl-functional sites has been obtained. The reaction of tmeda⋅(BH I) (1, tmeda=tetramethylethylendiamine) with different phosphanides yields the corresponding bidentate phosphanylboranes tmeda⋅(BH PH ) (2 a), tmeda⋅(BH PPh ) (2 b), and tmeda⋅(BH tBuPH) (2 c). This reaction strategy could be further extended to synthesize the first bidentate arsanylborane tmeda⋅(BH AsPh ) (3). Depending on the substituents on the phosphorus, these compounds form different Au complexes, to build either polymeric tmeda⋅(BH PH AuCl) (4 a), or monomeric tmeda⋅(BH PPh AuCl) (4 b) products. These compounds form also neutral oligomeric group 13/15 chain-like molecules by coordination to a boron moiety such as tmeda⋅(BH PH BH ) (5 a) and tmeda⋅(BH AsPh BH ) (5 b). DFT calculations provide insight into the differences between the syntheses of mono- and bidentate pnictogenylboranes.