Mono- and Bimetallic Cyclometalated Transition Metal NHC Complexes

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In the last years part of our research program involved the synthesis of cyclometalated NHC-complexes of different transition metals (Ag, Au, Ir, Pt, Ru). We focused on metalorganic compounds for use as phosphorescent emitters for OLEDs and catalytically active complexes. In the course of this research we noticed several compounds, which should possess a specific potential for photo-catalysis based on their absorption spectra and decay times of the excited state. One example might be a heteroleptic ruthenium complex [Ru(bpy)2(C^C*)](PF6) where the comparison with the analogous [Ru(bpy)3]2+ complex in appropriate test reactions should allow for insight into the active species. Furthermore we could synthesize bimetallic platinum(II) complexes with amidinate/pyrazolate ligands. Their metal-metal-distance is, according to a first assessment by quantum chemical calculations, strongly dependent from the groups at the amidinate/pyrazolate and the resulting geometry of the ligands, which should exert a strong influence on the formation of the excited state. This allows us to correlate the reactivity with the formation of the excited states. One important goal of this project therefore is the synthesis on new mono- and bimetallic cyclometalated C^C*-platinum(II) and –ruthenium complexes as well as the thorough study of already existing complexes with strikingly long decay times and suitable absorption spectra.Studying these compounds in model reactions will allow us to draw conclusions on the active species. The experimental work will be complemented by CV measurements and high-level DFT calculations with dispersion correction to evaluate the frontier orbitals and the excited states. For the very advanced spectroscopic investigations of the new compounds we hope that collaborations within the SPP will give access to that instrumentation.