Use of a two-sequential radical reaction scheme to rationalise the high-oxidation-state carbene species detected under confinement conditions for the interactions Fe(⁵D) + CH_4−n F_n (n = 2−4)

ABSTRACT

Results obtained from CASSCF–MRMP2 calculations are used to explain the carbene products observed under matrix conditions for the interactions Fe(⁵D) + CH_4–nF_n (n = 2–4) in terms of two sequential reactions involving the radical species ·FeF + CH_4–nF_n–1. For the CH₂F₂ and CHF₃ molecules, the first reaction leads to the radical fragments ·FeF + CH₂F (or ·CHF₂). As these species remain trapped in the matrix, they can recombine themselves to form the inserted complex CH₂F–Fe–F (or CHF₂–Fe–F). The carbene H₂C = FeF₂ (or HFC = FeF₂) is reached from the inserted structure by α-migration of an additional fluorine atom to the metal centre. The rebounding reactions can take place along both the quintuplet and triplet asymptotes varying only in the spin of the non-metal fragment. This model explains the triplet compound H₂C=FeF₂ detected for the interaction Fe + CH₂F₂ and allows theoretically assigning as quintuplet the complex HFC=FeF₂ observed for the reaction Fe + CHF₃.

KEYWORDS:

• Spin-flip
• radicals
• iron–fluorocarbons

Acknowledgments

This research was supported by the Universidad Nacional Autónoma de México (DGAPA-PAPIIT). We would like to thank DGCTIC–UNAM for the use of the Miztli supercomputer. G. Castro gratefully acknowledges CONACYT for her graduate scholarship (288877).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México [grant number IN113515]