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 2C 10H 6)(PPh 2H)] ( 1), fac-[Re(CO) 3{κ 1:κ 1:η 1-(O)PPh 2C 10H 6(O)PPh(C 6H 4)}] ( 2) and fac-[ReCl(CO) 3(κ 2-PPh 2C 10H 6PPh 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 2H 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 2C 10H 6PPh 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 10H 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.