Retrosynthetic approach to the design of molybdenum–magnesium oxoalkoxides

Abstract

The reaction of MoCl₅ methanolysis in the presence of magnesium ions was shown to produce an extensive row of heterobimetallic Mg–Mo(V, VI) oxomethoxides of different nuclearity ranging from 4 for [Mg₂(CH₃OH)₄Mo₂O₂(OCH₃)₁₀] (1) to 26 for [Mg(DMF)₃(CH₃OH)₃]₂[Mo₂₂Mg₄O₄₈(OCH₃)₂₈(DMF)₆] (2) with the latter possessing a ring morphology. Examination of [Mo₆O₁₂(OCH₃)₁₆Mg₄(CH₃OH)₆] (3), [Mo₆O₁₂(OCH₃)₁₂Mg₂(DMF)₄] (4a), and [Mo₆O₁₆(OCH₃)₄Mg₂(DMF)₈] (5a) X-ray structures revealed the presence of the well known tetranuclear core {Mo₄O₈(OCH₃)₂}²⁺ thus similar reactivity patterns leading to their formation were assumed. For convenient synthesis of such heterobimetallic oxoalkoxides, the retrosynthetic approach based on speculative deconstruction of a target molecule onto simpler fragments was suggested and successfully employed. Namely, the reaction of the stoichiometric amounts of appropriately chosen Mo(V), Mo(VI) and Mg²⁺ synthons led to their assembling resulting in the formation of heterometallic clusters 3, 5a and [Mo₆O₁₂(OCH₃)₁₂Mg₂(CH₃OH)₄]·2CH₃OH (4b) characterized by means of elemental analysis, UV-Vis, IR spectroscopy, and X-ray crystallography.