Ni(CO)4 - A test of the Hartree-Fock approximation for transition-metal compounds

✍ Scribed by K. Fægri Jr.; J. Almlöf

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 431 KB
• Volume: 107
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(84)85684-5

✦ Synopsis

Thegeometry of Ni(CO), has been optimized with basis sets of varying size, the larger ones being of near-Haruee-Fock quaIity.The best basis sets give a metal-&and bond distance 0.097 .S longer than experiment. Relativistic corrections have been obtained at the level of first-order pertubation theory, and yield a N-C bond contraction of 0.026 A.

1. ~n~oducrion

Recent work has shown that molecular-orbital calculations using finite basis sets of Gaussian functions in the Hartree-Fock appro~in~arion may suffer from severe shortcomings when used for geometry optimization with transition-metal compounds. Relevant cases are ferrocene and Fe(CO), , both of which yield bond lengths along the principal axis of sy!nmetry which are far too long. For ferrocene the optimised metal-ring distance is 0.23 a longer than what is found experimentally, an error that persists even as