Metal aryloxides mixed alkyl

This method has been used to produce a variety of homoleptic aiyloxide complexes and has also been applied to the synthesis of mixed alkyl, aryloxide derivatives of metals. Partial substitution is typically achieved by simple control of the stoichiometry or by using sterically demanding aryloxides (Eqs 6.49, 6.50, and 6.51 ). 

Table 6.1 Metal-ligand bond lengths for mixed alkyl, aryloxides of niobium and tantalum...

The reaction of mixed alkyl, aryloxides of the group 4 metals with CO has not yielded simple insertion products. However, final products are clearly the result of subsequent reactivity of y/ -acyl intermediates. The compound [(ArO)2Ti(t/ -R NCR)(R)] undergoes reaction with CO to produce the non-planar oxa-aza-metallacycle [(ArO)2Ti OC(R)=C(R)N(R ) ]. Carbonylation of [(ArO)2MR2] in the presence of pyridine remarkably leads to pyridine-di-melhoxide complexes. The threo and erythro isomeric mixture can be rationahzed on the basis of nucleophilic attack of acyl groups on coordinated pyridine figands. ... 

A large number of mixed alkyl, aryloxides of aU four metals have been obtained by reacting [MR3] with phenols. Monomeric bis(aryloxides) of aluminium, e.g. 

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