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A range of amines catalyse the oxidative addition (OA) of H 2 to [(Me 3 Si) 2 CH] 2 Sn ( 1 ), forming [(Me 3 Si) 2 CH] 2 SnH 2 ( 2 ). Experimental and computational studies point to 'frustrated Lewis pair' mechanisms in which 1 acts as a Lewis acid and involve unusual late transition states; this is supported by the observation of a kinetic isotope effect for Et 3 N. When DBU is used the energetics of H 2 activation are altered, allowing an equilibrium between 1 , 2 and adduct [ 1 ·DBU] to be established, thus demonstrating reversible oxidative addition/reductive elimination (RE) of H 2 at a single main group centre.

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