Unexpected B/Al Transelementation within a Rh Pincer Complex

Abstract

We report the synthesis of PAlP and PBP pincer complexes of Rh with a central bis(<i>N</i>-pyrrolyl)aluminyl or -boryl unit. Complex (PAl^pyP)Rh(CO)₂ possesses an aluminyl site stabilized by coordination of pyridine, resulting in a four-coordinate Al. Attempts to access the three-coordinate aluminyl by abstraction of pyridine with BF₃·Et₂O unexpectedly led to a B/Al metathesis with the preservation of the pincer structure in the product (PBP)Rh(CO)₂. Abstraction of pyridine was carried out using B(C₆F₅)₃, but the desired (PAlP)Rh(CO)₂ underwent dimerization via isocarbonyl bridging.