LOUIS J. FARRUGIA

Senior Lecturer

My major areas of research interest are:

• the determination of the molecular structure of inorganic complexes by X-ray diffraction and EXAFS spectroscopy.
• the synthesis, structure and reactivity of transition metal cluster compounds, especially heterometallic clusters and
• the coordination chemistry of pendant-arm macrocyclic complexes.

Synthesis and structural variability in heteroplatinum clusters

We have prepared a number of examples of small heteroplatinum and palladium clusters which exhibit a remarkable diversity in the structure of the metal skeleton. One example is the cluster Ru₃Pt(mu-H)(mu₄-NO)(CO)₁₀(P-Pr₃) which contains an highly unusual mu-eta2-nitrosyl group. Standard electron counting rules cannot account for this variability, but we believe it is due to the flexibility of platinum with regard to its electronic environment. We use both standard single crystal X-ray diffraction techniques as well as EXAFS studies (in collaboration with Professor A. G. Orpen, Bristol). See here for further details of this project. The EXAFS technique is one of the few ways of studying metal-core geometries in solution phase

Solid state migration of metals in clusters

We have recently studied the disordered structures of simple carbonyls of the type M₃(CO)₁₂ for M=Fe, Ru, Os. We find that the disorder in the mixed metal triangles is dynamic in nature, and that at low temperatures, the three systems we have investigated sofar Fe₂Ru(CO)₁₂ , Fe₂Os(CO)₁₂ and FeRu₂(CO)₁₂ are perfectly ordered. The structure of FeRu₂(CO)₁₂ is particularly interesting, in that it provides the first example of a homoleptic M₃(CO)₁₂ with the D₃ structure Through variable temperature X-ray crystallographic and solid state ¹³C MAS NMR we have shown that the most likely mechanism is one where the metal triangles move round in 60 degree steps, with the carbonyl ligands remaining relatively fixed. In particular the disordered structure of FeRu₂(CO)₁₂ provides a vivid picture of this migration pathway. See J.Chem.Soc. Dalton Trans. 1997 1783.

Solution fluxionality of hydrocarbyl ligands in clusters

We have investigated the fluxional properties of hydrocarbyl ligands such as sigma-(pi-vinyl) and alkynyl in small clusters using quantitative magnetisation transfer techniques such as DANTE and 2D EXSY. The EXSY experiment provides a "map" of all the site-to-site exchanges, and we have used this to investigate the migration of carbonyl ligands in a number of heterometallic clusters. These studies should provide insight into the mobility of ligands on metal surfaces, and under catalytic conditions.

Coordination chemistry of pendant arm macrocyclic ligands

In collaboration with Dr R. D. Peacock, we have been investigating the coordination chemistry of triaza-macrocycles with pendant arms bearing "soft" donor functionalities. A considerable number of such ligands with either one, two or three pendants arms with phosphine, alkene, alkyne or activated aryl donors have been prepared, and the coordination chemistry of these is being elaborated. The structure of one of these phosphine containing macrocycles is shown here.

I am also responsible for the software from
Chemical Crystallography, Glasgow including

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

Ten Recent Publications Illustrating Research Interests

1. A Structural Redetermination of Co₄(CO)₁₂ : Evidence for Dynamic Disorder and the Pathway of Metal Atom Migration in the Crystalline Phase. L. J. Farrugia, J. Organomet. Chem., 1999, 573, 60-66.

2. Metal Complexes of New, Chiral, N₂O₂ Tetradentate Ligands and their use as Asymmetric Oxidation Catalysts, R. J. Cross, L. J. Farrugia, P. D. Newman, R. D. Peacock and D. Stirling. Inorg. Chem., 1999, 38, 1186-1192.

3. N,N’,N"-1,4,7-triazacyclononane with pendant alkyne arms: Crystal structures of [CuL’₂][PF₆]₂, [NiL’₂][ClO₄]₂ and CuL"Cl₂ (L’ = N-(4-but-2-yne)-1,4,7-triazacyclo-nonane, L" = N-(5-pent-2-yne)-1,4,7-triazacyclononane). D. Ellis, L. J Farrugia and R. D. Peacock. Polyhedron 1999, 18,1229-1234.

4. Syntheses, crystal structures and CD spectra of simple heterobimetallic transition metal binaphtholates. R.J. Cross, L.J. Farrugia, D.R. McArthur, R.D. Peacock and D.S.C Taylor, Inorg. Chem. 1999, 38, 5698-5702.

5. WinGX Suite for Single Crystal Small Molecule Crystallography. L. J. Farrugia, J. Appl. Cryst. 1999, 32, 837-838.

6. Dynamic Disorder and Fluxionality in M₃(CO)₁₂ Clusters: Variable Temperature X-Ray Diffraction Studies on Fe_nRu_3-n(CO)₁₂ (n=1,2), and the Low Temperature Phase of Fe₃(CO)₁₂. L. J. Farrugia, A. L. Gillon, D. Braga and F. Grepioni, Organometallics, 1999 , 18, 5022-5033.

7. Structure and absolute configuration of exo-syn-syn-h⁵-cyclopentadienyl-dicarbonyl h³-(1R,2S,3S)-1-phenyl-2-buten-1-yl)-molybdenum (II). A. Kuhl, L.J. Farrugia and P.J. Kocienski, Acta. Cryst Sect C. 1999 .C55, 2041-2043.

8. Re-determination of the structure of the double salt D-[bis{tris(ethylene-diammine) cobalt(III) chloride}] sodium chloride hexa-hydrate. L. J. Farrugia, R. D. Peacock and B. Steward, Acta Cryst Sect. C 2000, C56, 149-151.

9. Structural Re-determination of Rh₄(CO)₁₂ at 293 and 173 K, and Analysis of the Thermal Motion in Relation to the Dynamical Behavior. L. J. Farrugia J. Clust. Sci. 2000, 11, 39-53.

10. A general route for the synthesis of triazacyclononane functionalised with one, two or three pendant phosphine arms. Crystal structures of [Zn₂L¹₂Cl₃] [ClO₄], [NiL¹Cl(HOEt)] [ClO₄] and [NiL¹(NCS)₂], L¹ = N-(diphenylphosphinopropyl)-1,4,7-triazacyclononane. D. Ellis, L. J. Farrugia, P. A. Lovatt and R. D. Peacock, Eur. J. Inorg. Chem. 2000, in the press.