Premium
The reactions of Cr(CO) 6 , Fe(CO) 5 , and Ni(CO) 4 with O 2 yield viable oxo‐metal carbonyls
Author(s) -
Sun Zhi,
Schaefer Henry F.,
Xie Yaoming,
Liu Yongdong,
Zhong Rugang
Publication year - 2014
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23585
Subject(s) - chemistry , metal carbonyl , metal , transition metal , dissociation (chemistry) , bond dissociation energy , inorganic chemistry , catalysis , crystallography , organic chemistry
Transition metal complexes with terminal oxo and dioxygen ligands exist in metal oxidation reactions, and many are key intermediates in various catalytic and biological processes. The prototypical oxo‐metal [(OC) 5 CrO, (OC) 4 FeO, and (OC) 3 NiO] and dioxygen‐metal carbonyls [(OC) 5 CrOO, (OC) 4 FeOO, and (OC) 3 NiOO] are studied theoretically. All three oxo‐metal carbonyls were found to have triplet ground states, with metal‐oxo bond dissociation energies of 77 (CrO), 74 (FeO), and 51 (NiO) kcal/mol. Natural bond orbital and quantum theory of atoms in molecules analyses predict metal‐oxo bond orders around 1.3. Their featured ν (MO, M = metal) vibrational frequencies all reflect very low IR intensities, suggesting Raman spectroscopy for experimental identification. The metal interactions with O 2 are much weaker [dissociation energies 13 (CrOO), 21 (FeOO), and 4 (NiOO) kcal/mol] for the dioxygen‐metal carbonyls. The classic parent compounds Cr(CO) 6 , Fe(CO) 5 , and Ni(CO) 4 all exhibit thermodynamic instability in the presence of O 2 , driven to displacement of CO to form CO 2 . The latter reactions are exothermic by 47 [Cr(CO) 6 ], 46 [Fe(CO) 5 ], and 35 [Ni(CO) 4 ] kcal/mol. However, the barrier heights for the three reactions are very large, 51 (Cr), 39 (Fe), and 40 (Ni) kcal/mol. Thus, the parent metal carbonyls should be kinetically stable in the presence of oxygen. © 2014 Wiley Periodicals, Inc.