HYPERVALENT BOND FORMATION IN HALOGENO(2-ACYLPHENYL)BISMUTHANES

Hypervalent bond formation has been found to occur at bismuth as the h ypervalent center. The transformation of (2-acetylphenyl)bis(4-methylp henyl)bismuthane (2b) to (2-acetylphenyl)bromo(4-methylphenyl)bismutha ne (3b) brings about a noticeable change in the electronic nature of t he carbonyl function in the 2-acetylphenyl group, which is sensitively reflected in the IR, H-1, and C-13 NMR spectra of compound 3b. These spectral changes may be rationalized in terms of the formation of a hy pervalent O-Bi-Br bond through intramolecular coordination of the carb onyl oxygen atom to the bismuth center. X-ray crystallography of 3b ha s confirmed this interpretation.