"The purpose of this project is to extend the chemistry of ruthenium and osmium clusters derived from N-heterocyclic carbenes (NHC) to the silicon, germanium and tin analogues (NHM, M = Si, Ge, Sn). The interest of this proposal is based on: (a) the absence of this kind of polymetallic compounds, (b) the interesting Ru3-NHC and Os3-NHC chemistry reported recently by Cabeza, Whittlesey, Cooke and Cole, amongst others, which cannot be replicated by mononuclear derivatives, and (c) the fact that Ru-NHC complexes are among the most active catalysts for key reactions in organic syntheses; for example olefin metathesis (including ring opening and closing processes) and a battery of cross-coupling reactions (Heck, Suzuki, Sonogashira, Stille and Kumada).The project will be divided in two main parts: (A) Stoichiometric reactions, including studies on: (i) the synthesis and characterisation of new Ru-NHM and Os-NHM cluster complexes, (ii) the ability of NHM ligands to promote intramolecular C–H, C–C, C–N, Si–N, Ge–N and Sn–N bond activations, (iii) the reactivity of the aforementioned derivatives toward unsaturated organic substrates, aiming C–C, C–N and M–heteroatom coupling reactions to form novel functionalised organic molecules, and (iv) theoretical calculations (DFT) to rationalize the transformations observed; and (B) Catalytic processes (olefin metathesis and coupling reactions) using the complexes outlined in part A or modified systems containing hemilabile ligands, able to promote the necessary coordination vacancies onto which the organic substrates can be fixed and transformed.This work will be developed in Cabeza´s Organometallic Cluster group (University of Oviedo-Spain), which its great experience in the area of ruthenium and osmium carbonyl clusters (derived from N-donor and NHC ligands), along with the promising possibilities that the fusion of NHM ligands and polymetallic compounds offer, provides all the necessary ingredients for a successful project."