Static Influence of Ligands: Comparison of DFT Calculations with Experimental Data

Abstract

The possibility of reproducing regularities of static mutual influence of ligands in complexes of Period V and VI elements of the Periodic Table (Pd, Sn, Sb, Pt, Pb) using the density functional theory (DFT) calculations is studied. Relativistic effects are taken into account by means of the Dirac equation approximation (zero-order regular approximation, ZORA). The calculations reproduced trans-influence in Pt complexes and trans-shortening and cis-elongation in the nontransition metal complexes. At the same time, Pb chloride complexes and Sn iodide complexes exhibit substantial differences between experimental and calculation bond lengths. When solvation was accounted for by COSMO method, DFT calculations reproduce the relative stability of the cis- and trans-Pt(NH3)2X2 complexes (X is halogen) and of the sulfur-containing Ni and Pd chelate complexes. The calculated geometry of the cis-Pt(NH3)2X2 molecule noticeably differs from the experimental geometry due to the overestimated strength of intramolecular N-H···X hydrogen bonds.