New molecular architectures containing low-valent cluster centres with di- and trimetalated 2-vinylpyrazine ligands: synthesis and molecular structures of Ru(CO)(μ-CHNCH[double bond, length as m-dash]CH)(μ-H) and Ru(CO)(μ-CHNCH[double bond, length as m-dash]C)(μ-H).

Reaction of 2-vinylpyrazine with Ru(CO) results in multiple C-H bond activations to afford penta- and octa-ruthenium clusters, Ru(CO)(μ-CHNCH[double bond, length as m-dash]CH)(μ-H) (2) and Ru(CO)(μ-CHNCH[double bond, length as m-dash]C)(μ-H) (3), in which a Ru sub-unit is linked to Ru and Ru centres di- and tri-metalated 2-vinylpyrazine ligands, exhibiting novel coordination modes including the loss of ring aromaticity in 2. The bonding of 2 and the mechanism for the fluxional behaviour of the hydrides have been examined by electronic structure calculations.