Mixed chloride–phosphine complexes of the dirhenium core: 9. The first mixed monodentate phosphine complex, 1,2,7,8-Re 2Cl 4(PMe 2Ph) 3(PEt 2H)

Abstract

The reduction of the Re 2 5+ core in 1,2,7-Re 2Cl 5(PR 3) 3 molecules, followed by addition of 1 equiv. of a different phosphine ligand, PR 3′, allows the preparation of the mixed monodentate phosphine compounds of the Re 2 4+ type, namely 1,2,7,8-Re 2Cl 4(PR 3) 3(PR 3′). The stereochemistry of the starting materials dictates the stereochemistry of the final products. The one-electron reduction of the 1,2,7-isomer of Re 2Cl 5(PMe 2Ph) 3 with KC 8 to the corresponding anion, [1,2,7-Re 2Cl 5(PMe 2Ph) 3] − ( 1), followed by non-redox substitution of one chloride ion by one diethylphosphine, PEt 2H, afforded the first mixed monodentate phosphine compound of the dirhenium(II) core, Re 2Cl 4(PMe 2Ph) 3(PEt 2H) ( 2), in good yield. Crystal structure determination as well as other physical methods and elemental analysis unambiguously confirmed the formation of 2. The related system 1,2,7-Re 2Cl 5(PMe 3) 3Co(C 5H 5) 2PEt 2H leads to several products, one of which is 1,2,7,8-Re 2Cl 4(PMe 3) 3(PEt 2H) ( 3).