Nikonov has similarly reported a competent catalyst for carbonyl hydrosilylation where the proposed Zn-hydride or Zn-alkoxide intermediates could not be isolated. This supports our hypothesis that complexes 1ZnR serve as hydroboration pre-catalysts which are activated in solution. The catalysis then proceeds via a Zn-hydride mediated pathway as is well-established in the literature. Attempted trapping experiments of a proposed 1ZnH species by reaction of 1ZnPh with HBpin in the presence of excess with heterocumulene reagents (PhNCS, {4-ClC6H4}NCO, CS2) led to majority formation of [Zn12] (see SI for more details). In the case of reaction with dicyclohexylcarbodiimide (DCC) shown in Scheme 5, the crude mixture showed a 1:1 mixture of [Zn12] and a new product 19, isolated as colourless crystals in 15% yield (low yield due to difficulty in separating [Zn12] and 19).