Catalytic processes leading to the functionalization of organic molecules by boron-containing reagents are highly topical ¿ ranging from transition metal catalysed hydro- and diboration of multiple bonds to direct hydrocarbon C-H activation. We have been investigating the use of metal borylene complexes [LnM(BNR2)] in related functionalization chemistry, a goal which necessitates the direct synthesis of such compounds from readily available borane reagents, of the types H3B.NHR2 or H2BNR2. In attempting to determine mechanistic details for the conversion of H3B.NHR2 to LnM(BNR2) we have uncovered a reversible ¿hydrogen shuttling¿ process, and are seeking access to neutron diffraction experiments in order to unambiguously define the structures of key intermediate species.