Reaction of cis-[Rh2(CH3COO) 2 (CH 3CN) 6](BF4)2 with two equivalents of 2-mesityl-1,8- naphthyridine (Mes-NP) affords trans-[Rh2(CH3COO) 2(Mes-NP) 2](BF4) 2 (1). X-ray structure reveals weak RhC(ipso) interaction, and a short RhRh distance. The same ligand, in contrast, oxidatively cleaves the RuRu bond in cis-[Ru2 (CO) 4 (CH3CN) 6](BF4)2 and results in trans-[Ru(Mes-NP) 2 (CH3CN) 2](BF4)2 (2). Both compounds adopt trans geometry to relieve the steric strain. Compound 2 exhibits moderate activity for the alcohol oxidation and aldehyde olefination reactions. © CSIRO 2011.