Experiments to reduce the phosphine and silane loadings (Table , entries 8-10) showed that using a close to stoichiometric (in terms of hydride equivalents) amount of Ph2SiH2 still allowed good conversion to 2 (87%), although the reaction was slower and a small amount of 3 (2 %) was formed alongside the desired product (Table , entry 8). Reduction of the phosphine loading to 5 mol% was still very effective, albeit slower (93% 2 after 1h), and at 1 mol% selective formation of 2 was still possible, but reaction times were much longer (83% yield after 18h) and some unreacted 1 (11%) was present after this time. Given the low cost of both P n Bu3 and Ph2SiH2 it was decided to use the reaction conditions in Table , entry 6 for further studies, as these led to fast reactions without a significant increase in cost.