A Scandium Complex Bearing Both Methylidene and Phosphinidene Ligands: Synthesis, Structure, and Reactivity

Abstract

The scandium complex bearing both methylidene and phosphinidene ligands, [(LSc)2(μ2-CH2)(μ2-PDIPP)] (L = [MeC(NDIPP)CHC(NDIPP)Me]−, DIPP = 2,6-(iPr)2C6H3) (2), has been synthesized, and its reactivity has been investigated. Reaction of scandium methyl phosphide [LSc(Me){P(H)DIPP}] with 1 equiv of scandium dimethyl complex [LScMe2] in toluene at 60 °C provided complex 2 in good yield, and the structure of complex 2 was determined by single-crystal X-ray diffraction. Complex 2 easily undergoes nucleophilic addition reactions with CO2, CS2, benzonitrile, and tert-butyl isocyanide. In the above reactions, the unsaturated substrates insert into the Sc–C(methylidene) bond to give some interesting dianionic ligands while the Sc–P(phosphinidene) bond remains untouched. The bonding situation of complex 2 was analyzed using DFT methods, indicating a more covalent bond between the scandium ion and the phosphinidene ligand than between the scandium ion and the methylidene ligand.