Computational Studies of the Electronic Structures and Mechanisms of Late Transition Metal Systems

Abstract

Late transition metal species are heavily studied because of their diverse applications in industrial, synthetic, and biological processes. Transition metals can alter the thermodynamic aspects of a reaction by creating an alternative, lower-energy pathway, which is not accessible without a metal. Numerous investigations have been performed to better understand the elementary steps within these reactions. The significant increase in available computing power coupled with the further development of transition-metal friendly quantum chemical methods has assisted in making computational chemistry an important method in predicting transition-metal mechanisms. This dissertation is divided into four parts, one for each of the transition-metal systems that were studied.

The first system focuses on the formation of a carbon-bromine bond from the reaction of Ni(Ar)(Br)(pic) (Ar = 2-phenylpyridine, pic = 2-picoloine) with Br2. Unlike the typical behavior of heavier group 10 metals that have a wider range of stable oxidation states, Ni was found to undergo a change multiplicity during this reaction. The mechanism proceeds through a triplet state pathway that is stabilized by a Br2-/NiIII interaction instead of the NiIV singlet state pathway. The second two systems are concerned with inter- and intramolecular carbon-hydrogen bond activation, respectively. In the second system the lifetimes of carbon-hydrogen activation of four cycloalkanes with the Cp’Rh(CO) fragments (Cp’= η5-C5H5 or η5-C5Me5) were calculated. The lifetimes were found to be dependent of the size of the cycloalkane reacting and the number of possible reaction paths associated with the specific cycloalkane. A intramolecular carbon-hydrogen bond activation mechanism was calculated for the RuII(SC6H3Me2-2,6-κ1S)2(PMe3)3 species for the third system. The dominant pathway was predicted to be the equatorial mechanism which proceeds through a σ-bond metathesis reaction. The final transition-metal system involves the transfer of CuI from the Atox1 metal binding site to a metal binding domain on the ATP7A or ATP7B proteins. This system was found to proceed through a dissociative pathway wich each two-coordinate and three-coordinate species stabilized by adopting the optimized the S lone pair/Cu 3d π-overlap.