Bonding in bis(pentalene)dimolybdenum: Density functional calculations on Mo-2(C8H6)(2) and photoelectron spectroscopy of Mo-2(C8H4(1,4-SiPr3i)(2))(2)

He I and He II photoelectron spectra are reported for Mo-2[C8H4(1,4-SiPr3i) (2)](2). Density functional calculations on the model compound Mo-2(C8H6)(2 ) give a structure with bond lengths and ionization energies in good agreem ent with those found for Mo-2[C8H4(1,4-SiPr3i)(2)](2) Fragment analysis of the bonding in Mo-2(C8H6)(2) indicates a double bond between the two Mo ato ms. The bonding to the pentalene ligands is very covalent and resembles tha t found for simple metallocenes.