"Computational analysis of the unusual lability of Ru (xantsil) (CO) (n6-C6H5CH3) using semi-empirical PM3 calculations"

Date

10-2005

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Jim Josephus G. Minglana

Co-adviser

Emily V. Castriciones

Abstract

The extremely facile arene exchange of Ru(xantsil)(C0)(toluene) (complex 3) at room temperature was analyzed using Semi-empirical Parametrization Method 3 (PM3) Calculations with Spartan 2002. The bond distances and bond angles o the said complex were constrained according to the XRD data. To be able to compare the effect of the presence of the silicon atoms, the carbon analog of complex 3 was also studied. Analysis of bond distances and bond angles, the IR v(CO), the minimum energy for the optimized geometry; and the electronic factors such as atomic charges, and the molecular orbital analysis, suggests that the presence of the strong a- donating silyl groups is the main contributing factor for the unusual lability of the Ru-toluene bond. The silyl groups donate electron density to Ru and this increases back-donation of the metal to the empty n'-orbitals of CO and toluene. The Electrostatic Potential Surfaces (EPS) of complex 3 clearly reveals the susceptibility of the toluene ligand to nucleophilic attack. This was also verified by the atomic charges on the toluene carbons. This was not seen in the carbon analog 3-C. Trans influence was not included in the analysis performed here but it is highly recommended to further study the trans-effect on the lability of the toluene ligand using this approach. It is also recommended to study by computational methods reaction mechanisms of the facile arene exchange and other related reactions of complex 3 to get a better understanding of the effect of silicon on the lability of toluene in the complex

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2005 C4 H57

Document Type

Thesis

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