2006/03/10 by T. Tsuchiya, Takashi Tsuchiya, B. O. Roos +1 · 15 citations
Chemistry · Engineering · Materials Science · Physics and Astronomy · #Advanced Chemical Physics Studies #Atomic physics #Bond length #Catalytic Processes in Materials Science #Chemistry #Computational chemistry #Crystal structure #Crystallography #Double bond #Excited state #Ground state #Hessian matrix #Inorganic chemistry #Molecular Junctions and Nanostructures #Molecule #Physics #Potential energy #Singlet state #Spin (aerodynamics) #Spin states #Thermodynamics #Triple bond #Triplet state
paper · doi:10.1080/00268970500417135
published in Molecular Physics 104(5-7), 1123-1131 (Taylor & Francis)
openalex publication_date 2006/03/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
The spin-forbidden reaction of Fe(CO)4 + CO → Fe(CO)5 has been investigated with multiconfigurational quantum chemical methods (CASSCF/CASPT2). The structure of the minimum energy crossing point (MECP) between the singlet and triplet energy surfaces as well as the equilibrium structures of Fe(CO)5 (a singlet state) and Fe(CO)4 (a triplet state) has been determined. The partition rational function (RF) method has been used for the geometry optimization together with approximate numerical gradient vectors and Hessian matrices. The Fe–CO bond angles of the MECP are between those of the equilibrium structures of the ground states of Fe(CO)5 and Fe(CO)4, while a considerable extension of the Fe–CO bonds have been shown to occur at the MECP when transferring from the triplet (reactant) PES to the singlet (product) PES. It has also been shown that the MECP prefers to have a C s symmetry structure with the incoming CO tilted rather than a C 2v structure with Fe and the incoming CO on a straight line.