N‑Heterocyclic Phosphenium Complexes of Vanadium

Isolable N-heterocyclic phosphenium (NHP) complexes of
vanadium
were prepared by cophotolysis of Na[V(CO)6] and 2-bromo-1,3,2-diazaphospholenes.
Single-crystal XRD studies revealed that the complexes exhibit trigonal
planar coordination at phosphorus and short P–V distances indicative
of phosphorus–metal double bonding. An exemplary reaction with
Li[BEt3H] proceeded via hydride transfer to the phosphorus
atom to yield an anionic secondary phosphine complex, which resisted
protonation by [Et3NH]Cl and differed in this aspect from
a previously reported manganese-based analogue. DFT calculations were
carried out to analyze metal–ligand interactions in the NHP
vanadium complexes and to rationalize the different behavior of the
vanadium- and manganese-based species in H–/H+-transfer reactions.