Vanadium oxo-alkoxides

The formation of 3-methyl-2-buten-l-ol, 4, and of 3-methyl-2-butenal, 5, in some experiments can be related to the isomerization of la and subsequent oxidation of product 4, thus formed, to 5. We observed that the vanadium oxo-alkoxide, [OV(OC3H7)3], is a good precursor for the catalytic epoxidation of substrates la, lb and Ic with systems involving tert-butyl hydroperoxide and tertiary allylic alcohols. These systems proved to be more active than those involving [VO(acac)2] usually associated with anhydrous r-BuOOH in benzene or toluene (Figure 1 and Table 2). 

Although synthesis of VO(OR)3 by the reaction of V2O5 with alcohols was described as early as 1913, " only a few more vanadium oxo-alkoxides " appear to have been synthesized as shown by Eqs (2.77) and (2.78) ... 

The chemistry of vanadium is replete with 0x0 vanadium complexes including a large number of vanadium oxo-alkoxides. 

Vanadium Sub-group Metal-containing Oxo-alkoxides (Including Heterometallic Compounds) (Table 5.5)... 

Table 5.5 Vanadium sub-group metal-containing oxo-alkoxides (including heterometallic compounds)... 

A vanadium(v)-molybdenum(vi) heterometallic oxo-alkoxide [V2Mo2(0)g (0Me)2 (0CH2)3C(CH20H) 2] has also been characterized. The V2M02O16 core involving octahedral metals is reminiscent of the Ti40ie core of titanium tetraUcoxides. ... 

The X-ray crystal structures of a terminally oxo-bonded vanadium alkoxide [VO(OCH2CH2Cl)3]2 (496), shown in Fig. 73, reveals dimeric association of molecules belonging to adjacent unit cells via long V—OCH2CH2Cl bonds [2.261(2) A], and a trigonal bipyramidal geometry for each vanadium atom in the dimeric molecule. 

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