Production of Ammonia and Search for a Catalytic System

At that time Alan Pearman was working with me as a D. Phil, student and I set him the task of looking at the chemistry of the NNH2 compounds. He examined their deprotonation to give NNH complexes and the displacement of the three-electron donor NNH ligand by the isoelectronic NO ligand to give nitrosyl complexes, as illustrated in Equations (8) and (9).  

Having exhausted our enthusiasm for the dppe system, we decided to move on to monophosphine complexes, expecting to observe similar behaviour, perhaps with more lability in the products. It was our habit to run these reactions in sealed flasks and measure the gas evolved to give a mass balance. 

We now set out with high optimism first to characterise our system as far as possible, and then to use this knowledge to design a commercial catalyst, not realising at the time that attainment of a catalytic system that would work even under laboratory conditions was to prove elusive for some ten years. 

Using this chemistry as the basis, Chris Pickett and Jean Talarmin were later able to develop later an electrochemically-driven cycle for the reduction of N2 to NH3, thus establishing in principle the vision that Joseph had held from early days in the UNF, that a low-technology electrochemical process for generating ammonia for agriculture could be achieved. 

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