On the bonding in transition-metal compounds: A comparison of LDF and HF results for Ni(CO)₄

Assuming tetrahedral symmetry, a geometry optimization for Ni(CO)₄ has been performed using the LCGTO Xα method. The results for various spectroscopic constants are in satisfactory agreement with experiment. However, the values for the metal-carbon bond length, for the frequency of the corresponding stretching motion and for the dissociation energy indicate a slight overestimation of the metal-carbon bond strength. The contrasting findings for the nickel-distance from the HF and the Xα method are correlated with their description of pertinent metal configurations.