Fluoro-complexes of ruthenium, iridium and rhodium
The experimental work presented in this Thesis details the synthesis and characterisation of a range of low-valent fluoro-complexes of ruthenium, rhodium and iridium, and appraises the compatibility of a metal-bound fluoride with a range of different ligand architectures. Phosphorus- and nitrogen-based ligands form the bedrock of the research. In addition, NHCs (N-heterocyclic carbenes) have been extensively exploited in this Work, and the assimilation of both fluoride and NHC within a ligand manifold has been realised. This Work illustrates that cleavage of the fluoride-bridged tetramer [RuF[subscript 2](CO)[subscript 3] ][subscript 4] with an appropriate monodentate ligand is a reliable route into fluoro-complexes of the generic form [RuF[subscript 2] (CO)[subscript 2] (L)[subscript 2]]. The scope of this methodology is wide-ranging; reaction of [RuF[subscript 2](CO)[subscript 3] ][subscript 4] with sterically demanding NHCs is facile, providing the first well-defined examples of transition metal fluoro-complexes incorporating NHCs within the co-ordination sphere. The spacial properties of the NHC play a crucial role in determining the fate of the fluoro-complex; when employing sterically unencumbered NHCs, double cyclometallation was observed, affording two novel cyclometallated fragments. This Work also demonstrates that direct oxidative addition of XeF[subscript 2] across a neutral or cationic Ir[superscript (I)] centre, with the desired ligand scaffold already in place, is a valid preparative technique for the generation of some novel Ir[superscript (III)] fluoro-complexes. This synthetic protocol is not limited solely to iridium chemistry, and a brief foray into the chemistry of rhodium fluorocomplexes is also presented. By judicious manipulation of the ligand scaffold, a number of Ir[superscript (III)] and Rh[superscript (III)] fluoro-complexes incorporating NHCs within the ligand architecture have been isolated. The complexes have been analysed using a variety of techniques, including multinuclear NMR spectroscopy, IR spectroscopy and mass spectrometry. Where possible, molecular compositions have been confirmed through elemental analyses. In addition, many of the complexes have been subject to an X-ray diffraction study, and detailed discussions of representative molecular structures are given at relevant points in the text.