Reversible coordination of N2 and H2 to a homoleptic S = 1/2 Fe(i) diphosphine complex in solution and the solid state

Laurence R Doyle; Daniel J Scott; Peter J Hill; Duncan A X Fraser; William K Myers; Andrew J P White; Jennifer C Green; Andrew E Ashley

doi:10.1039/c8sc01841c

Reversible coordination of N₂ and H₂ to a homoleptic S = 1/2 Fe(i) diphosphine complex in solution and the solid state

Chem Sci. 2018 Jul 18;9(37):7362-7369. doi: 10.1039/c8sc01841c. eCollection 2018 Oct 7.

Authors

Laurence R Doyle¹, Daniel J Scott¹, Peter J Hill¹, Duncan A X Fraser¹, William K Myers², Andrew J P White¹, Jennifer C Green², Andrew E Ashley¹

Affiliations

¹ Department of Chemistry , Imperial College London , London SW7 2AZ , UK . Email: a.ashley@imperial.ac.uk.
² Inorganic Chemistry Laboratory , University of Oxford , Oxford OX1 3QR , UK.

Abstract

The synthesis and characterisation of the S = 1/2 Fe(i) complex [Fe(depe)₂]⁺[BArF4]^- ([1]⁺[BArF4]^-), and the facile reversible binding of N₂ and H₂ in both solution and the solid state to form the adducts [1·N₂]⁺ and [1·H₂]⁺, are reported. Coordination of N₂ in THF is thermodynamically favourable under ambient conditions (1 atm; ΔG ₂₉₈ = -4.9(1) kcal mol^-1), while heterogenous binding is more favourable for H₂ than N₂ by a factor of ∼300. [1·H₂]⁺[BArF4]^- represents a rare example of a well-defined, open-shell, non-classical dihydrogen complex, as corroborated by ESR spectroscopy. The rapid exchange between N₂ and H₂ coordination under ambient conditions is unique for a paramagnetic Fe complex.