Bonhoeffer was a wonderful scientist and man... a person. Many know of the fate of the Bonhoeffer family during the Nazi time. His brother, who was a Protestantic priest, was killed by the Nazis even a few months before the end of the war. They were involved in the uprising of the 20th July against Hitler. Bonhoeffer himself was a wonderful character and he tried to further young people. He was famous for having discovered the two modifications of hydrogen, ortho- and parahydrogen, together with Harteck and with Eucken. Eucken did at that time measurements of the specific heat, and so the three shared this discovery. At that time it was a very important discovery because explanation required quantum mechanics and when Heisenberg received his Nobel Prize in the early '30s, the formulation of his prize was for the discovery... for the explanation of the two modifications of hydrogen, which was ortho- and parahydrogen.

Yes, Bonhoeffer then went on to use... was one of the first in Germany to use D20, heavy water, for following by the isotope... following the course of complicated reactions, and at that time after the war he was very interested in biology. He always tried to persuade me to study reactions. He was especially interested in nerve conduction and made a model of that, but I always had to tell him I first want to study more fundamental reactions to understand better the course of complicated reactions before I would go into such complicated problems, as we know nowadays biological reactions are.

The same was... I was asked when I came to the Faraday meeting in 1954, why we studied magnesium sulphate ‒ such a boring substance. Well, this was just a fact that we started from the sound absorption of sea water, so that was not our choice, magnesium sulphate was given. But, anyway, reactions between metal ions and ligands usually are fast reactions. And there was a complete open field for us to study and many inorganic chemists came into our laboratory during the '50s, and studied fast reactions.  So I almost became a coordination chemist and I was always invited to meetings of coordination chemistry.