New molecular architectures containing low-valent cluster centres with di- and trimetalated 2-vinylpyrazine ligands: synthesis and molecular structures of Ru 5 (CO) 15 (μ 5 -C 4 H 2 N 2 CH[double bond, length as m-dash]CH)(μ-H) 2 and Ru 8 (CO) 24 (μ 7 -C 4 H 2 N 2 CH[double bond, length as m-dash]C)(μ-H) 3 .

Reaction of 2-vinylpyrazine with Ru 3 (CO) 12 results in multiple C-H bond activations to afford penta- and octa-ruthenium clusters, Ru 5 (CO) 15 (μ 5 -C 4 H 2 N 2 CH[double bond, length as m-dash]CH)(μ-H) 2 (2) and Ru 8 (CO) 24 (μ 7 -C 4 H 2 N 2 CH[double bond, length as m-dash]C)(μ-H) 3 (3), in which a Ru 3 sub-unit is linked to Ru 2 and Ru 5 centres via 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.