Electrospray ionization photoelectron spectroscopy: Probing the electronic structure of inorganic metal complexes in the gas-phase

The coupling of electrospray to photoelectron spectroscopy has allowed a number of negatively charged solution phase transition-metal complexes to be transferred to the gas-phase and studied by photoelectron spectroscopy for the first time. Experiments have been performed on a range of species, including classic square-planar and octahedral transition-metal halide complexes, metal–metal bonded species, transition-metal bis(dithiolene) centers and a variety of mononuclear and polynuclear iron–sulfur clusters that are related to important bioinorganic centers. The studies have provided detailed information about the electronic structure and molecular orbital energy levels of these species, allowing for direct comparison with theoretical calculations, and providing insight into their intrinsic redox properties in the absence of solvation.