Wide-bite-angle diphosphinines: Design, synthesis, and coordination properties

A wide-bite-angle diphosphinine ligand has been designed and synthesized, which exhibits structural features for a preferred formation of trans complexes. Due to the linear orientation of the lone-pair electrons of the phosphorus donors in combination with an appropriate P-P distance, trans coordination toward a Rh center was observed and the corresponding LRh(CO)I complex could be characterized crystallographically. Although typical reactivities usually observed for trans complexes were found, reaction of the diphosphinine with the cis-enforcing precursor [Rh(nbd)₂]BF₄ did result in the formation of several species at low temperature, to which cis-structures were attributed.