Binuclear ruthenium(II) complexes with polypyridil bridging ligands: Gas-phase chemistry and ligand structure

Ru(II) binuclear complexes with the general formula [(Ru[9]aneS3Cl)2(μL)](PF6)2, where μL = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), 2,3-bis(2-pyridyl)pyrazine (dpp), and 2,2′-bipyrimidine (bpym), have been studied by electrospray mass spectrometry (ESI/MS) and electrospray mass spectrometry/mass spectrometry (ESI/MS/MS), in the positive ion mode, to investigate their fragmentation patterns in relation to their structural and spectroscopic properties and also to find out the differences with the gas-phase fragmentations patterns of their mononuclear counterparts.We observed that the presence of two connected metal centres leads to the formation of specific ionic species, in particular, for the compound with bptz, gas-phase formation of fluoride anion adducts. These species can be related to the electronic structure of the bptz compound, in particular to its LUMOs (lowest unoccupied molecular orbitals) that lye low than the LUMOs of the other two compounds.