Reactions of rhenium and manganese carbonyl complexes with 1,8-bis(diphenylphosphino)naphthalene: Ligand chelation, C-H and C-P bond-cleavage reactions

Abstract Reaction of [Re 2 (CO) 8 (MeCN) 2 ] with 1,8-bis(diphenylphosphino)naphthalene (dppn) afforded three mono-rhenium complexes fac -[Re(CO) 3 (κ 1 :η 1 -PPh 2 C 10 H 6 )(PPh 2 H)] ( 1 ), fac -[Re(CO) 3 {κ 1 :κ 1 :η 1 -(O)PPh 2 C 10 H 6 (O)PPh(C 6 H 4 )}] ( 2 ) and fac -[ReCl(CO) 3 (κ 2 -PPh 2 C 10 H 6 PPh 2 )] ( 3 ). Compounds 1 – 3 are formed by Re–Re bond cleavage and P–C and C–H bond activation of the dppn ligand. Each of these three complexes have three CO groups arranged in facial fashion. Compound 1 contains a chelating cyclometalated diphenylnaphthylphosphine ligand and a terminally coordinated PPh 2 H ligand. Compound 2 consists of an orthometalated dppn-dioxide ligand coordinated in a κ 1 :κ 1 :η 1 -fashion via both the oxygen atoms and ortho -carbon atom of one of the phenyl rings. Compound 3 consists of an unchanged chelating dppn ligand and a terminal Cl ligand. Treatment of [Mn 2 (CO) 8 (MeCN) 2 ] with a slight excess of dppn in refluxing toluene at 72 °C, gave the previously reported [Mn 2 (CO) 8 (μ-PPh 2 ) 2 ] ( 4 ), formed by cleavage of C–P bonds, and the new compound fac -[MnCl(CO) 3 (κ 2 -PPh 2 C 10 H 6 PPh 2 )] ( 5 ), which has an unaltered chelating dppn and a terminal Cl ligand. In sharp contrast, reaction of [Mn 2 (CO) 8 (MeCN) 2 ] with slight excess of dppn at room temperature yielded the dimanganese [Mn 2 (CO) 9 {κ 1 -PPh 2 (C 10 H 7 )}] ( 6 ) in which the diphenylnaphthylphosphine ligand, formed by facile cleavage of one of the P–C bonds, is axially coordinated to one Mn atom. Compound 6 was also obtained from the reaction of [Mn 2 (CO) 9 (MeCN)] with dppn at room temperature. The XRD structures of complexes 1 – 3 , 5 , 6 are reported.