Syntheses of Heteronuclear Molybdenum/Bismuth Alkoxides Stabilized by Organic Ligands

Reaction of [((CH3)C3H4)Mo(CO)2(CH3CN)2Cl], 2, with [Bi(OEt)3]x provides the heterotetranuclear complex [((CH3)C3H4)Mo(CO)2(μ-OEt)3Bi(μ-OEt)2Bi(μ-OEt)3Mo(CO)2((CH3)C3H4)], 3, in good yields. If 2 is reacted with [Bi(OCH2CH2OCH3)3]2, a dinuclear chloro alkoxide [((CH3)C3H4)Mo(CO)2(μ-κO,2κO‘-OCH2CH2OCH3)2(μ-Cl)BiCl], 4, is obtained, while pretreatment of 2 with AgBF4 and subsequent reaction with [Bi(OCH2CH2OCH3)3]2 leads to
the chloride-free complex [((CH3)C3H4)Mo(CO)2(μ-κO,2κO‘-OCH2CH2OCH3)3Bi(thf)][BF4], 6,
with a Bi center surrounded by seven oxygen donors. All compounds have been characterized
by NMR and IR spectroscopy as well as elemental analysis, and their crystal structures
were determined by means of single-crystal X-ray diffraction. 3, 4, and 6 belong to the few
compounds known (there is only one other precedent) where Mo and Bi centers are bridged
by oxygen-containing ligands and can therefore be considered as cornerstones on the way to
the synthesis of yet unknown molecular compounds with Mo−O−Bi functions resembling
those occurring on the surface of nMoO3−Bi2O3 catalysts.