SPECTRAL STUDIES OF SOME COMPLEXES OF "RIBOFLAVIN-2',3',4',5'-TETRAACETATE

The preparations are reported of complexes of riboflavin-2′,S′,4′,5′-tetraacetate with salts of cobalt(II), nickel(II) and copper(II). Electronic spectra indicate that the flavin is bonded to the metal through O4 and N5, the MN bond being probably rather weak. The CO stretching vibrations are shifted to lower energy on coordination. The electronic spectra of enzyme-substrate complexes involving flavin groups are discussed in the light of results for the metal complexes. © 1979.