Theoretical Studies on the Mechanisms of Chemical Reactions

             

Principal Investigator

Brian Yates

School of Chemistry,

University of Tasmania

Powerful computers and the most modern algorithms are being used to help design better
catalytic systems for the synthesis of industrially important products such as polyketones, plastic polymers which provide a photodegradeable alternative to polyethylenes. The ANUSF computer facilities are being used to improve the organometallic catalysts in a systematic manner and to provide a theoretical basis and understanding for many of the experimental observations.
In our School, experimental and theoretical work has focussed on using Pd(II) complexes containing pyridine carboxylate (NC5H4COO­) and di-nitrogen ligands to explore the fundamental mechanistic steps. With the use of the VPP300 and the Power Challenge we have been able to carry out calculations on model complexes approaching the complexity of the experimental systems. These calculations would not have been possible without access to these high performance computing facilities.

As a result of this ongoing research we have

· obtained detailed descriptions of possible reaction mechanisms for the copolymerisation of CO and ethene using prototype neutral and cationic catalysts

· determined the effect of different phosphine ligands (PF3, and PH3)

· obtained information for different chelating ligands (NO and NN donors)

· provided a theoretical basis for the observation that a trans N­donor activates CO and a trans P­donor activates an alkyl group for migratory insertion

· determined precise changes in activation energies as a function of several electronic and steric effects

· determined a rationale that can be applied to similar ligands and metals.

This project was supported by both small and large ARC grants.

 

Co-Investigators

     

Katrina Frankcombe

Trent Wale

School of Chemistry,

University of Tasmania

     

Projects

g29 - VPP, PC

     
           
             
Appendix -

             
         
         
   

- Appendix B
 
       

What computational techniques are used?

We have used quantum chemistry techniques (mainly conventional ab initio SCF and MP2 methods together with density functional methods) as implemented in the Gaussian 94 program. This package has been well-vectorised and makes good use of the VPP and PC. We have employed large basis sets together with relativistic effective core potentials to enable geometry optimisations and wavefunction analyses to be carried out reliably.

Publications

K. E. Frankcombe K. J. Cavell, R.B. Knott, B. F. Yates, Competing Reaction Mechanisms for the Carbonylation of Neutral Palladium(II) Complexes Containing Bidentate Ligands: a Theoretical Study, Organometallics, 16, 1997, 3199-3206.

       
Appendix -