Reactivity of molybdenum and rhenium hydroxo complexes toward organic electrophiles: reactions that afford carboxylato products

The reactions of the hydroxo complexes [Mo(OH)(eta(3)-methallyl)(CO)(2)(phen)] (1) and [Re(OH)(CO)(3)(Me-2-biPY)] (2) (phen = 1,10-phenanthroline, Me-2-bipy= 4,4'-dimethyl-2,2'-bipyridine) with maleic anhydride, phenyl(ethyl)ketene, diphenylketene, and rac-lactide afford new carboxylato complexes. The molybdenum and rhenium hydroxo complexes react in the same way, and their reactions are quantitative. The products, some of which have been characterized by X-ray diffraction, feature monodentate O-bonded carboxylato ligands, and their treatment with triflic acid yields the triflato complexes [Mo(OTf)(eta(3)-methallyl)(CO)(2)(phen)] and [Re(OTf)(CO)(3)(Me-2-bipy)] and the corresponding free carboxylic acid.