The interaction of trans-W(N-2)(2)(dppe)(2) (1; dppe = 1,2-bis(diphenylphosphino)ethane) with relatively weak acids (p-nitrophenol, fluorinated alcohols, CF3COOH) was studied by means of variable temperature IR and NMR spectroscopy and complemented by DFT/B3PW91-D3 calculations. The results show, for the first time, the formation of a hydrogen bond to the coordinated dinitrogen, W-N equivalent to N center dot center dot center dot H-O, that is preferred over H-bonding to the metal atom, W center dot center dot center dot H-O, despite the higher proton affinity of the latter. Protonation of the core metal-the undesirable side step in the conversion of N-2 to NH3-can be avoided by using weaker and, more importantly, bulkier acids.