Mass spectral and theoretical characterisation of non-symmetric Mo(V) dithiolene complexes

The gas phase fragmentations of a family of three anionic complexes of molybdenum(V), [Mo2(O)2([mu]-S)2([eta]2-S2)2]2-, [Mo2(O)2([mu]-S)2([eta]2-S2) ([eta]2-S2C2H2)]2-, [Mo2(O)2([mu]-S)2([eta]2-S2)([eta]2-S2C2(C6H5)2)]2- were studied as a function of the collision energy used in the collision cell of a triple quadrupole analyser. The main fragment ion for the three anions was Mo2S4O2- at low collision energies, while higher collisional activation led to cleavage of the "metal-metal" bond. Topological analyses of the electronic domains using the electron localisation function (ELF) showed that non-symmetric fragmentation behaviour could be interpreted according to the least topological change principle. Fragmentation induced a slight shift of the electron density towards the remaining ligands and an increase of the electron population on the Mo atom that undergoes a decrease of its coordination sphere.