Studies on transition-metal peroxo complexes. Part 7. Molybdenum(VI) and tungsten(VI) carboxylato peroxo complexes, and the X-ray crystal structure of K2[MoO(O2)2(glyc)]·2H2O

Abstract

New complexes [MoO(O₂)₂L]^2–[L = malate, tartrate (tart), tartronate, quinate, or glycolate (glyc)], [WO(O₂)₂L]^2–(L = citrate, tartrate, malate, or glycolate), and [W₂O₂(O₂)₄(tart)]^4– are reported, and modified preparations given for [MO(O₂)₂L]^2– and [MO₂(O₂)L(H₂O)]^2–(M = Mo or W; L = oxalate). Raman and i.r. spectra of the solid complexes, and Raman, ¹³C and ⁹⁵Mo n.m.r. spectra of their aqueous solutions, have been measured and are used to suggest the structures of the species in the solid state and solution. The X-ray crystal structure of K₂[MoO(O₂)₂(glyc)]·2H₂O has been determined: triclinic, space group P, with a= 7.222(4), b= 7.950(6), c= 10.450(5)Å, α= 67.81(4), β= 73.72(7), γ= 64.84(4)° at 20 °C, and Z= 2; the structure has been refined to R= 0.035.