N -Phosphinoamidinato Silylene- and Phosphine-Borylborylene Complexes.

This work describes a straightforward method to synthesize a borylborylene without proceeding via the rearrangement of a diborene. An amidinato amidosilylene [LSiNMe 2 ] (L = PhC(N t Bu) 2 ) and PMe 3 were reacted with an N -phosphinoamidinato diborane 1 and KC 8 to form a stable silylene-borylborylene 2 and a persistent phosphine-borylborylene 3 , respectively. Compound 2 is stable as the borylene center is well stabilized by the silylene donor and boryl substituent, whereas compound 3 is unstable in solution due to labile PMe 3 . The latter was illustrated by reacting compound 3 with Ar'NC (Ar' = 2,6-Me 2 C 6 H 3 ), where Ar'NC displaced PMe 3 and inserted into the N -phosphinoamidinate ligand and B-B bond to form compound 4 .