The catalytic conversion of N to N(SiMe) by homogeneous transition metal compounds is a rapidly developing field, yet few mechanistic details have been experimentally elucidated for 3 d element catalysts. Herein we show that Fe(PP)(N) (PP = RPCHCHPR; R = Me, 1; R = Et, 1) are highly effective for the catalytic production of N(SiMe) from N (using KC/MeSiCl), with the yields being the highest reported to date for Fe-based catalysts. We propose that N fixation proceeds via electrophilic N silylation and 1e reduction to form unstable Fe(NN-SiMe) intermediates, which disproportionate to 1 and hydrazido Fe[N-N(SiMe)] species (3); the latter act as resting states on the catalytic cycle. Subsequent 2e reduction of 3 leads to N-N scission and formation of [N(SiMe)] and putative anionic Fe imido products. These mechanistic results are supported by both experiment and DFT calculations.

The first cationic Fe silyldiazenido complexes, [Fe(PP)2(NN–SiMe3)]+[BArF4]− (PP = dmpe/depe), have been synthesised and thoroughly characterised. Computational studies show the compounds to be useful structural and electronic surrogates for the more elusive [Fe(PP)2(NN–H)]+, which are postulated intermediates in the H+/e− mediated fixation of N2 by Fe(PP)2(N2) species

Effective enantioselective reduction of ketimines has been demonstrated by ‘frustrated’ Lewis pair catalysis using an IBiox-stabilised borenium cation.

Cationic Lewis acids (LAs) are gaining interest as targets for frustrated Lewis pair (FLP)-mediated catalysis. Unlike neutral boranes, which are the most prevalent LAs for FLP hydrogenations, the Lewis acidity of cations can be tuned through modulation of the counteranion; however, detailed studies on such anion effects are currently lacking in the literature. Herein, we present experimental and computational studies which probe the mechanism of H 2 activation using i Pr 3 SnOTf ( 1 -OTf) in conjunction with a coordinating (quinuclidine; qui) and noncoordinating (2,4,6-collidine; col) base and compare its reactivity with { i Pr 3 Sn·base}{Al[OC(CF 3 ) 3 ] 4 } (base = qui/col) systems which lack a coordinating anion to investigate the active species responsible for H 2 activation and hence resolve any mechanistic roles for OTf – in the i Pr 3 SnOTf-mediated pathway.