Comparative Study of Mono- and Dinuclear Complexes of Late 3d-Metal Chlorides with N,N-Dimethylformamide in the Gas phase

Mono- and binuclear complexes of N,N-dimethylformamide (DMF) with chlorides of the divalent, late 3d metals M = Co, Ni, Cu, and Zn are investigated by means of electrospray ionization (ESI). Specifically, ESI leads to monocations of the type [(DMF)(n)MCl](+) and [(DMF)(n)M2Cl3](+), of which the species with n = 2 and 3 were selected for in-depth studies. The latter include collision-induced dissociation experiments, gas-phase infrared spectroscopy, and calculations using density functional theory. The mononuclear complexes [(DMF)(n)MCI](+) almost exclusively lose neutral DMF upon collisional activation with the notable exception of the copper complex, for which also a reduction from Cu-II to Cu-I concomitant with the release of atomic chlorine is observed. For the dinuclear clusters, there exists a competition between loss of a DMF ligand and cluster degradation via loss of neutral MCl2 with decreasing cluster stability from cobalt to zinc. For the specific case of [(DMF)(n)ZnCl](+) and [(DMF)(n)Zn2Cl3](+), ion-mobility mass spectrometry indicates the existence of two isomeric cluster ions in the case of [(DMF)(2)Zn2Cl3](+) which corroborates parallel theoretical predictions.