The near infrared2Π3/2(aβJ) ¬ X2Σ+(bβS) band systems of TiCo and ZrCo

Abstract

Resonant two-photon ionization spectroscopy has been used to provide the first rotationally resolved work involving multiply-bonded mixed early–late transition metal dimers. The mixed metal dimers TiCo and ZrCo are shown to possess2Σ+ground states, in agreement with a previous matrix isolation ESR (electron spin resonance) study on TiCo. Two previously observed vibronic bands in ZrCo are rotationally resolved, as is one of several newly discovered vibronic transitions in TiCo. Ground-state rotational constants for48Ti59Co and90Zr59Co are measured to be B''0= 0.186 15(8) cm–1and B''0= 0.119 78(5) cm–1, giving r''0= 1.8508(4) and r''0= 1.9883(4) Å, respectively. In both molecules the ground state conforms to the Hund's case (bβ S) coupling scheme, with Fermi contact interactions between the unpaired σ electron and the59Co (I = 7/2) nucleus of b''F= 0.0468(7) cm–1for48Ti59Co and b''F= 0.0549(6) cm–1for90Zr59Co. These values indicate that the unpaired electron occupies a σ orbital having 32% and 37% Co 4s character in TiCo and ZrCo, respectively. All three of the rotationally resolved bands are2Π3/2¬ X2Σ+transitions. For90Zr59Co the 0 ¬ 0 and 1 ¬ 0 bands were resolved at ν0= 10 496.1452(28) and 10 884.3794(25) cm–1, giving B'0= 0.119 82(6) and B'1= 0.121 44(5) cm–1. For48Ti59Co the rotationally resolved band has ν0= 9873.8342(19) cm–1and B' = 0.191 07(6) cm–1. These results are discussed in the context of prior work on these and related molecules. PACS No.: 33.20Eq