15min:

MELISSA A. BAUDHUIN, PRAVEENKUMAR BOOPALACHANDRAN, SRIJAY S. RAJAN AND DOREEN G. LEOPOLD, Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 .

We report the 488 nm photoelectron spectrum of the NbCr^- anion. For the ² ground state of neutral NbCr, the short bond length (1.894 Å) and high bond energy (D₀ 3.0263(6) eV) measured by R2PI spectroscopy indicate high order multiple bonding. We find that the NbCr^- anion has a ^{1 +} ground state, in which the "extra" electron occupies the (4d) bonding orbital, giving a 1 ²1 ⁴1 ⁴2 ² valence electron configuration and a formal bond order of 6. Low-lying excited states of NbCr (assigned as two ^{2 +} states) and NbCr^- (³ ) are also observed. The spectra provide the electron affinity of NbCr, energies of the ^{2 +} and the ³ excited states, vibrational frequencies for the NbCr and NbCr^- ground states and for the ^{2 +} excited states, and (from Franck-Condon analyses) differences among the bond lengths of the observed states. These results are compared with our previous data for the Group 5/6 congeners NbMo, VCr, and VMo, and with DFT predictions. We also report results for ongoing experiments on the flow tube reactions of the Group V metals Nb and Ta with butadiene, and the vibrationally-resolved photoelectron spectra of some of the organometallic reaction product anions.