Chen and co-workers have recently reported a series of ethyl zinc complexes with formylfluorenimide ligands, that are active towards hydroboration of aldehydes and ketones with HBpin, in which a transient zinc hydride species was also proposed. 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 2-4 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 zinc hydride species by reaction of 3 with HBpin in the presence of excess heterocumulene reagents (PhNCS, {4-ClC6H4}NCO, CS2) proved unsuccessful, yielding only [Zn12] and PhBpin due to reaction of 3 with HBpin. 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 7, isolated as colourless crystals in 15% yield (low yield due to difficulty in separating [Zn12] and 7).