Reduced-Dimensionality Quantum Dynamics Study of the 3Fe(CO)4 + H2 → 1FeH2(CO)4 Spin-inversion Reaction

Abstract

Many chemical reactions of transition metal compounds involve a change in spin state via spin inversion, which is induced by relativistic spin-orbit coupling. In this work, we theoretically study the efficiency of a typical spin-inversion reaction, 3Fe(CO)4 + H2 → 1FeH2(CO)4. Structural and vibrational information on the spin-inversion point, obtained through the spin-coupled Hamiltonian approach, is used to construct three degree-of-freedom potential energy surfaces and to obtain singlet-triplet spin-orbit couplings. Using the developed spin-diabatic potential energy surfaces in reduced dimensions, we perform quantum nonadiabatic transition state wave packet calculations to obtain the cumulative reaction probability. The calculated cumulative reaction probability is found to be significantly larger than that estimated from the one-dimensional surface-hopping probability. This indicates the importance of both multidimensional and nuclear quantum effects in spin inversion for polyatomic chemical reaction systems.

Spin‐inversion mechanisms in O2 binding to a model heme compound: A perspective from nonadiabatic wave packet calculations

“…1 FeH 2 (CO) 4 spin-inversion reaction. [52] These theoretical studies along with the present study indicate that coupling between the nonadiabatic spin-inversion motion and other nuclear motions plays an essential role leading to multidimensional nonlocal transitions. Thus, we qualitatively conclude that the multidimensional and nuclear quantum effects play an important role in spin-inversion processes for polyatomic systems although more systematic dynamics studies should be performed to understand the effect of missing nuclear degrees of freedom.…”

“…In Figure The SOC values are calculated at some selected points because it is expected that the magnitude of SOC does not depend substantially on the structure. [52] In this work, the SOCs are determined within the Breit-Pauli approximation (with the SOMF approximation) [53] using the state-interacting method at the state-averaged CASSCF/ def2-TZVP level of theory. These electronic structure calculations are performed using the ORCA program.…”

Photochemistry of transition metal carbonyls

“…97,138 A multidimensional method reports better agreement with experiment for the reaction with H 2 but does not calculate the rate constant. 139 Baerends et al 133 have also addressed the preference for PH 3 dissociation for ax-Fe(CO) 4 (PH 3 ) and shown by quantum dynamics that there is a strong preference for dissociation of PH 3 over CO on population of the lowest excited state, but the details are different from those described for Cr(CO) 5 PH 3 . The theory of H 2 dissociation from Fe(CO) 4 (H) 2 has been addressed by Daniel 140 by CASSCF methods.…”

“…97,138 A multidimensional method reports better agreement with experiment for the reaction with H 2 but does not calculate the rate constant. 139…”