Reversible coordination of N<inf>2</inf>and H<inf>2</inf>to a homoleptic: S = 1/2 Fe(i) diphosphine complex in solution and the solid state

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 N2and H2in both solution and the solid state to form the adducts [1·N2]+and [1·H2]+, are reported. Coordination of N2in THF is thermodynamically favourable under ambient conditions (1 atm; ΔG298= -4.9(1) kcal mol-1), while heterogenous binding is more favourable for H2than N2by 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 N2and H2coordination under ambient conditions is unique for a paramagnetic Fe complex