Organometallic Mo-O-Bi complexes

The reaction between Ph₃BiBr₂ and wet [NBu₄]₂[MoO₄] leads to a white solid that according to Klemperer and Liu analyses as [NBu₄]₂[BiPh₃(MoO₄)₂] · 3H₂O (1^aq). Working under strictly anhydrous conditions allowed us the isolation of the solvate-free complex [NBu₄]₂[BiPh₃(MoO₄)₂] (1), which in contrast to 1^aq could also be characterised by means of single crystal X-ray diffraction. The results reveal a structure with a Bi^V ion being surrounded by three phenyl substituents and two molybdate units. Remarkably the resulting two Mo^VI-O-Bi^V linkages are linear and according to a DFT investigation this is due to a predominantly ionic interaction between the O and Bi atoms. Moreover a novel Mo^VI-O-Bi^III complex, NBu₄[{Cp∗Mo(O)₂-μ-O-}₂(Bi(o-tolyl)₂)] (2), has been prepared via reaction of the coordination polymer [(Cp∗Mo(O)₂)-μ-O-(Bi(o-tolyl)₂)]_n with [NBu₄][Cp∗MoO₃] and the crystal structure of 2 has been investigated. According to DFT results the character of the bonds within the bent Mo-O-Bi unit is described most appropriately as covalent. The structure of 2 is discussed also with respect to corresponding Mo-O-Bi moieties occurring in bismuthmolybdate catalysts, for which it could represent a molecular structural model.