π-Excess aromatic σ2P ligands: Unprecedented reductive C–C coupling of neopentylbenzazaphosphole at the PCH–N group by Fe3(CO)12 to an heterocyclic 1,2-bis(phosphido)-Fe2(CO)6 complex

Abstract The aromatic P CH–N heterocycle 1 with dicoordinated phosphorus (σ 2 P) reacts with Fe 3 (CO) 12 in toluene or benzene under reductive C–C coupling and coordination of the [Fe 2 (CO) 6 ] 2+ fragment to the μ 2 -bridging 1,2-bis(phosphido)Fe 2 (CO) 6 chelate complex 2 (rac/ meso 4:1 to 2:1). This reaction illustrates the potential of Fe 3 (CO) 12 for C–C coupling reactions of easily reducible unsaturated heterocycles which may act as both, substrate and ligands for coordination of the resulting Fe 2 (CO) 6 fragment. The products were identified by characteristic NMR data of the bis(dihydrobenzazaphospholide) ligands and rac - 2 ·1.5 CDCl 3 by crystal structure analysis.