DFT-SQM force field for cobalt corrinoids

This Letter introduces a systematic development of a quantitative vibration al force field (FF) capable of modeling vibrational spectra of cobalt corri noids (B-12 derivatives). The scaled quantum mechanical (SQM) method is use d to refine density functional theory (DFT) based force constants calculate d at the B3LYP level of theory. The reliability of the DFT-SQM FF for cobal t corrinoids is tested on a six-coordinate methylcobalamin Im-[Co-III-corri n]-CH3 model. It is shown that the computed frequencies and Raman intensiti es permit detailed vibrational assignment. This analysis illustrates the ut ility of DFT-SQM FF in making detailed connections between the structure of cobalt corrinoids and their vibrational spectra, (C) 2000 Elsevier Science B.V. All rights reserved.