ab initio calculations of co shielding in model complexes从头开始计算模型有限公司屏蔽的复合物.pdfVIP

Int. J. Mol. Sci. 2002, 3, 873-887 International Journal of Molecular Sciences ISSN 1422-0067 © 2002 by MDPI /ijms/ Ab Initio Calculations of Co Shielding in Model Complexes Elaine A. Moore Department of Chemistry, The Open University, Milton Keynes, MK7 6AA, UK Tel.: +44 (0) 1908 655028, Fax: +44 (0) 1908 858327, E-mail: e.a.moore@open.ac.uk URL: http://www.open.ac.uk/science/chemistry Received: 26 November 2001 / Accepted: 10 May 2002 / Published: 31 August 2002 Abstract: Recent ab initio calculations of cobalt NMR shielding show that DFT-GIAO calculations using hybrid functionals are found to reproduce experimental values well. This method is used to calculate the variation of the cobalt NMR shielding tensor of sqaure pyramidal nitrosyl complexes with respect to the CoNO geometry and to differing basal ligands. The isotropic shielding is shown to have a large negative derivative with respect to CoX distance where X is a ligating atom.; the derivative with respect to NO distance is smaller but still significant. The zz component where z is along the CoN(NO) bond is more sensitive to the basal ligands but the other two principal components are sensitive to the CoNO geometry. Keywords: 59Co, NMR shielding, DFT, ab initio calculations, NO Introduction The scope