BOND STRENGTHS OF TRANSITION-METAL DIATOMICS - ZR-2, YCO, YNI, ZRCO, ZRNI, NBCO, AND NBNI

The observation of an abrupt predissociation threshold in an extremely congested electronic spectrum, has been used to measure the bond diss ociation energies of the mixed early-late transition metal molecules Y Co, YNi, ZrCo, ZrNi, NbCo, and NbNi. In these systems it is argued tha t predissociation occurs as soon as the ground separated atom limit is exceeded, providing values of D-0(0)(YCo) = 2.591 +/- 0.001 eV, D-0(0 )(YNi) = 2.904 +/- 0.001 eV, D-0(0)(ZrCo) = 3.137 +/- 0.001 eV, D-0(0) (ZrNi) = 2.861 +/- 0.001 eV, D-0(0)(NbCo) = 2.729 +/- 0.001 eV, and D- 0(0)(NbNi) = 2.780 +/- 0.001 eV. In addition, the bond strength of dia tomic zirconium has been measured as D-0(0)(Zr-2) = 3.052 +/- 0.001 eV . A discussion of the Chemical bonding in the mixed early-late transit ion metal dimers and Zr-2 is presented;based on the measured bond ener gies of these species.