Terminal imido rhodium complexes

Abstract

Compounds of the late transition metals with M=X multiple bonds (X=CR2, NR, O) represent a synthetic challenge, partly overcome by preparative chemists, but with noticeable gaps in the second- and third-row elements. For example, there are no isolated examples of terminal imido rhodium complexes known to date. Described herein is the isolation, characterization, and some preliminary reactivity studies of the first rhodium complexes [Rh(PhBP3)(NR)] (PhBP3=PhB{CH2PPh2}3) with a multiple and terminal Rh=N bond. These imido compounds result from reactions of organic azides with the corresponding rhodium(I) complex having a labile ligand, and display a pseudo-tetrahedral core geometry with an almost linear Rh-N-C arrangement [177.5(2)°] and a short Rh-N bond [1.780(2) Å]. We also show that the Rh=N bond undergoes protonation at the nitrogen atom or addition of H2 , and also engages in nitrene-group transfer and cycloaddition reactions.

Keywords: azides; cycloaddition; multiple bonds; rhodium; structure elucidation.