Detailed electronic description of triple bonds between transition metal atoms and verification by photoelectron spectroscopy.

Using the SCF-Xalpha-SW method the ground state electronic structures of (HO)(3)Mo identical withMo(OH)(3), (H(2)N)(3)Mo identical withMo(NH(2))(3), and (Me(2)N)(3)Mo identical withMo(NMe(2)) have been calculated. The results provide a detailed description of the metal-to-metal triple bonds present; some of the more important molecular orbitals are shown in detail as contour diagrams. The energy levels of all filled valence shell/molecular orbitals and the lower virtual orbitals are presented in diagrams. The pi(e(u)) and sigma(a(1g)) orbitals which have large amounts of metal character can be identified as the orbitals primarily responsible for Mo-Mo bonding. Using the transition state technique to allow for relaxation effects, the photoelectron spectra (up to 12 eV) have been calculated for Mo(2)(OH)(6) and Mo(2)(NH(2))(6) and found to compare very well, after applying a constant downshift to correct for inductive effects, with experimental spectra for Mo(2)[OCH(2)C(CH(3))(3)](6) and Mo(2)[N(CH(3))(2)](6). The experimental photoelectron spectra are reported.