Reactivity of acetone oxime towards oxomolybdenum(VI) complexes. Part 1. Syntheses and crystal structures of tetranuclear molybdenum(VI) complexes

Abstract

Reaction of acetone oxime with [NBuⁿ₄]₄[α-Mo₈O₂₆] in refluxing methanol yielded [NBuⁿ₄]₂[Mo₄O₁₂(Me₂CNO)₂]1 while that with [MoO₂(acac)₂](acac = acetylacetonate) at room temperature resulted in the formation of [Mo₄O₁₀(OMe)₄(Me₂CNHO)₂]2. The crystal structures of 1 and 2 have been determined [1, space group P, a= 9.009(1), b= 17.860(1), c= 16.769(1)Å, α= 91.624(5), β= 101.158(7), γ= 91.983(7)°, R= 0.037 for 7429 reflections with I > 3σ(I); 2, space group P2₁/c, a= 9.437(1), b= 8.827(1), c= 13.727(3)Å, β= 92.15(1)°, R= 0.029 for 2821 reflections with I > 3σ(I)]. The anion of 1 displays a cyclic (MoO₂)₄(µ-O)₄ ring while 2 displays a Mo^VI₄(µ₃-OMe)₂ central core. The µ₄-κ²N:κ²O co-ordination mode exhibited by the acetone oximate in 1 is unprecedented for such a ligand, so is the end-on co-ordination mode of zwitterionic acetone oxime in 2. The reactivity of 1 and 2 respectively towards hydrochloric acid and tetrabutylammonium hydroxide was studied.