Dual-electrospray synthesis: A method of studying unique coordination complexes in the gas phase

Abstract

Tris(2,2′-bipyridine)ruthenium(II) and similar complexes containing the 1,10-phenanthroline ligand were formed by spraying a ligand solution and a ruthenium trichloride solution through two independent electrospray (ESI) emitters. This was confirmed by comparing ion mobility drift time, mass spectra, and energy-resolved collision-induced dissociation (CID) breakdown curves with the corresponding reference standards. The complexes of 2,2′-bipyridine and 1,10-phenantroline with iron(II), and their mixed-ligand complexes formed by dual-spray exhibited two additional hydrogen atoms. By CID, these unique gas phase complexes showed similar initial ligand loss to the reference standards, however the sequential ligand loss showed unique dissociation channels and energetics. Density functional theory calculations of the [Fe(phen)3+2H]2+ complex and its fragment ions suggest that, after the initial loss of one ligand, the additional hydrogen atoms transfer to the central iron atom. The relative energy of the dissociation channels showed good agreement with experimental breakdown curves.