Photoreaction of [MoH4(Ph2PCH2CH2PPh2)2] with allyl carbonates to give hydridocarbonatomolybdenum(II) complexes; X-ray crystal structure of a seven-co-ordinate molybdenum(II) complex [MoH(O2COEt)(Ph2PCH2CH2PPh2)2]

Abstract

Reaction of [MoH₄(dppe)₂](1)(dppe = Ph₂PCH₂CH₂PPh₂) with allyl alkyl carbonates R′O₂COCH₂CHCH₂(R′= Me or Et) in benzene under irradiation with a high-pressure mercury lamp afforded [MoH(O₂COR′)(dppe)₂](2) together with propene and H₂. The seven-co-ordinate complexes (2) were characterized spectroscopically as having a pentagonal-bipyramidal structure in solution and the X-ray crystal structure of (2; R = Et) has been determined: triclinic, space group P with a= 16.400(6), b= 18.828(7), c= 11.821 (3)Å, α= 96.22(3), β= 99.47(3), γ= 128.76(2)°, Z= 2, and R= 0.057. It has a very distorted pentagonal-bipyramidal geometry with the two phosphorus atoms, hydride, and two oxygens of the carbonate ligand comprising the pentagonal girdle, in which the last two ligands are mutually trans.