Organometallic Complexes of Benzannelated Phospholyls: Synthesis and Characterization of Benzophospholyl and the First iso-Benzophospholyl Metal Complexes

A large-scale synthesis of the benzophospholyl (BP) ligand, 4, has been developed and employed in the synthesis of a series of manganese and iron complexes. Reaction between Li-BP and FeCp(CO)2X (X = Br, I) resulted in the formation of [(μ2-BP)Fe2Cp2(CO)4]X, while reaction of bis(1,1'-benzophospholyl) with [FeCp(CO)2]2 gave a mixture of isomers of (μ2-BP)2Fe2Cp2(CO)2. The phosphine adduct (BP-Ph)Mn2(CO)9 was obtained from BP-Ph and Mn2(CO)10 and converted to (η5-BP)Mn(CO)3 upon reaction with organometallic or organic radicals. A synthesis for phenyl-iso-benzophosphole (iBP-Ph) has been explored. The compound is highly reactive and polymerizes instantaneously and irreversibly. Polymerization of the iBP precursor was avoided in the novel partially hydrogenated derivative iBP-H2-Ph. Manganese complexes of iBP, 5, were obtained by reaction of iBP-H2-Ph with Mn2(CO)10, resulting in the formation of (η5-iBP-H2)Mn(CO)3. Reaction of (η5-iBP-H2)Mn(CO)3 with DDQ gave (η5-iBP)Mn(CO)3, the first metal complex of iBP.