Louis J. Farrugia - Research Interests

My current areas of research interest are:

• charge density studies on transition metal complexes
• the determination of the molecular structure of inorganic complexes by X-ray diffraction.
• software for Chemical Crystallography

Charge density studies involve the direct experimental measurement of the electron distribution in molecules and hence provide detailed information about the chemical bonding between atoms. In Glasgow we have superb experimental facilities to undertake this work, including three state-of-the-art single crystal X-ray diffractometers, a Nonius KappaCCD, Bruker-Nonius APEX-II and a Rigaku R-Axis Rapid. The Atoms in Molecules (AIM) topological approach of Richard Bader and coworkers has revolutionised the analysis of charges densities and is being increasingly applied to experimental results. The AIM theory attempts to explain chemical bonding in molecules directly from the electronic charge density, in contrast to most theoretical approaches which utilise analysis of the wavefunction and associated molecular orbitals. Our experimental charge density study on manganese carbonyl was recently highlighted in an IUCr newletter.

I am a member of the XD programming team, which produces the XD computer program for the AIM analysis of experimental charge densities, used in 100 laboratories worldwide. I was involved as a tutor in the last XD Workshop in Buffalo, NY in 2003.

Here in Glasgow we are investigating the topologies of the experimental charge densities in coordination complexes and organometallic complexes, with a view to obtaining a profounder understanding of metal-metal and metal-ligand interactions. We have now completed charge density studies on manganese decacarbonyl (pdf reprint here), on the binary carbonyls Cr(CO)6, Fe(CO)5 and Ni(CO)4 (pdf reprint here), and on tricobalt alkylidyne clusters (pdf reprint here). We are currently focusing on the nature of the delocalised interaction between a metal and pi-bonded hydrocarbyl ligands. These interactions are proving difficult to characterise through examination of the bond critical points alone.

Laplacian of the charge density through the Mn-Mn bond in Mn2(CO)10) Atomic graph of the Mn atom in Mn2(CO)10) The interatomic surfaces of the C atom in (a) CO and (b) Cr(CO)6

Software for Chemical Crystallography

I am also responsible for much of the software from Chemical Crystallography, Glasgow of which the most utilised software are the MS-Windows programs Ortep for Windows and WinGX.

	Ortep-3 for Windows with new POV-Ray interface
	WinGX - crystallographic program system for Windows

Other research topics

Some previous reseach areas are illustrated here