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Quantification of the Ligand effects in transition metal coordination compounds using electronic structure calculation methods


EMSL Project ID
12700a

Abstract

The ligand bonding effects described by the σ-donor and π-acceptor capacities of the ligands in relation to the π-donor and σ-acceptor capacities of the molecular fragments containing the central metal atoms or ions are the key to the understanding of the structural, energetic, electronic and catalytic properties of transition metal coordination compounds. Therefore, all attempts to quantify these effects either by experimental or theoretical parameters are of a great potential interest, for it could help us to design coordination compounds with novel properties and technological applications. Our summer research project proposal would be focused on the calculation of the redox potentials of a series of closed shell octahedral Cr(CO)5L and Ru(NH3)5L complexes in the gas as well as in the liquid phase. The ligands L will be selected on the basis of their position in the entire spectrochemical series, ranging from the pure σ-donors to the strong π-acceptors. State-of-the-art computational techniques (ab initio and DFT) combined with a reliable, flexible and accurate basis sets, should be used to calculate the redox potentials, as well as other structural and electronic properties of the transition metal coordination compounds. These properties will subsequently be used as descriptors of the ligand bonding effects in order to develop quantitative relationships between the redox potentials and the molecular parameters, such as the HOMO eigenvalue, the vibrational frequencies, the atomic charges, the hardness, etc. as well as with experimental data such as the PL and pKa constants. Moreover another goal of our study will be the generation of a database of DFT-calculated descriptors either for donor or acceptor ligands in a range of representative complexes. Prototype ligand knowledge base (LKB), resulting from various statistical analysis methods should be used for the study of specific properties, as well as for the prediction of properties concerning novel or untested ligands.
We believe that the proposal to be successfully performed collaboration with the highly qualified staff and the use of the state-of-the-art research facilities at PNNL is a prerequisite. Through such collaboration our training and experience with advanced theoretical techniques would indeed be maximized.

Project Details

Project type
Exploratory Research
Start Date
2006-12-01
End Date
2007-10-02
Status
Closed

Team

Principal Investigator

Constantinos Tsipis
Institution
Aristotle University of Thessaloniki

Team Members

Christos Kefalidis
Institution
Aristotle University of Thessaloniki