New cyclopentadienyl molybdenum polynuclear clusters from ring opening of Woollins’ reagent via phosphorus–selenium bond scission, phosphorus–phosphorus coupling and deselenation pathways

Abstract

Cothermolysis of [(Ph)P(Se)(μ-Se)]2 or Woollins’ reagent (WR) with Cp2Mo2(CO)4 (2) in toluene at 110°C led to the isolation of three different metal clusters, [Cp2Mo2{(μ-Se)2(PPh(Se))}{(μ-Se)(PPh)3] (3), Cp4Mo4(CO)3(μ-Se)4 (4) and a pair of isomer complexes of Cp3Mo3(CO)4[Se3(PPh)2] (5a and 5b) in 17.5%, 3.1% and 4.9% yields, respectively. A similar reaction at 70°C gave only 5a and 5b in 2.0% and 4.9% yields, respectively. All complexes have been fully characterized via NMR, IR and ESI mass spectroscopy. Molecular structures of 3, 4 and 5a were confirmed by single crystal X-ray diffraction analyses. A variable temperature 1H NMR study of 4 was carried out. Finally, a free-radical addition pathway by selenation of WR was postulated.