Rhenium-Oxygen and Rhenium-Phosphorus Multiple Bonds in High Valent, π-Loaded Complexes

We report several complexes of rhenium with oxo and phosphinidene groups supported by a bulky BDI ligand (BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate). A monomeric rhenium oxo-phosphinidene complex was found to be accessible via successive dehydrohalogenation reactions from an oxo-phosphine precursor. The primary phosphine and phosphido complexes formed en route to this oxo-phosphinidene complex were also characterized, as was an isomeric decomposition product of the oxo-phosphinidene complex. The oxo-phosphinidene complex was employed in the synthesis of rhenium-Group 9 heterobimetallic bridging phosphinidene complexes. Proceeding in a complementary direction, a BDI rhenium tris-oxo species was synthesized from the bis THF adduct of chlorotrioxorhenium. This complex proves to be competent for the stoichiometric oxidation of 1,3-cyclohexadiene, forming a diolato complex. The tris-oxo species was determined to be unstable in solution. One of the decomposition products was crystallographically characterized; it features an α-ketoimine ligand derived from the oxidation of the γ-carbon in the backbone of the BDI ligand.