A computational investigation of inorganic systems using ab initio methods

Advances in computer technology have allowed computational chemists to apply ab initio techniques to more complicated chemical systems. The complicated systems under investigation here are a rhodium (III) complex and heteroclusters of the form WN-(NH3)n. Employing a pseudopotential basis set and standard computational methods, a configurational investigation of RhCl2(222-S4)+ where 222-S4 = (RCH2S(CH2)2S(CH2) 2S(CH2)2SCH2R)+ was conducted. Computational results suggest that the configurational preference of this system is a result of both steric crowding of terminal groups and ligand bite-size. Results obtained using the ONIOM method also support this conclusion provided an acceptable chemical model was used. In the heterocluster study, results obtained using density functional theory were found to be comparable to MP2(full) data. It was found that the subsequent addition of NH3 to HCN exhibited cooperative hydrogen bonding, lengthening of the C-H bond, shortening of the H3N...H-CN interaction, and a movement of negative charge away from the acidic hydrogen. Results obtained using solvation models show the same trends as gas phase results when the first hydrogen bond between solute and solvent is included.