Bypassing a highly unstable frustrated Lewis pair: dihydrogen cleavage by a thermally robust silylium-phosphine adduct

The thermally robust silylium complex [iPr(3)Si-PtBu3](+)[B(C6F5)(4)](-) (1) activates H-2/D-2 at 90 degrees C (PhCl); no evidence for dissociation into the separated Lewis pair is found. DFT calculations show H-2 cleavage proceeds via Si-P bond elongation to forman encounter complex directly from the adduct, thus avoiding the non-isolable iPr(3)Si(+)-PtBu3 FLP.