Just as with ferrocene, 1 the formula first written for diborane B2H6 was orthodox, in conformity with the usual paradigmatic rules regarding molecular structure. And it was wrong. Correcting the mistake showed an extremely unusual bonding picture for the molecule. Just as in the ferrocene case, it opened up a whole new chapter of chemistry, later recognized with the award of a Nobel prize to William N. Lipscomb in 1976 for “his studies on the structure of boranes illuminating problems of chemical bonding.”
I shall highlight here only a few episodes from the diborane story. In 1937, a former student of Linus Pauling, Simon H. Bauer – incidentally he is still active in research at Cornell, at the age of 88 – applied the technique of electron diffraction, a tool which he had learned to use at Caltech with Pauling, to diborane. He found and he reported a structure analogous to that of ethane, which therefore he wrote as H3B-BH3. 2 In 1942, Bauer reiterated his contention of the ethane-like structure for diborane. 3 At the same time of the early 1940s, H.I. Schlesinger, a chemistry professor at the University of Chicago, was also working on boron compounds. One of the reasons was his involvement in the Manhattan Project: it was thought that an isotope separation could be devised for uranium using such derivatives. In any case, Schlesinger was very much interested in the structure of diborane.