Erich Hückel¹ was a German physicist. He is not very famous among non-scientists. Possibly because he never went Nobel. Erich Hückel brought solvation models and quantum mechanics to chemistry. A chemistry student will inevitably bump into some of Hückel's theories or models. While his name is attached to a series of models and methods his biography has remained widely unknown.

Early Years

Erich Armand Arthur Joseph Hückel was born on 9 August, 1896 in Charlottenburg, a suburb of Berlin, Germany. Erich grew up in an intellectually stimulating environment. His father Armand was a physician (internist and psychiatrist) who was on his way up in the academic ranks. He wouldn't have had the time to conduct scientific experiments with his three sons (Walter², Erich and Rudi³) if he hadn't had his academic career blocked. The reason? Armand married outside of his social class to Marie Maier, a peasant's daughter - these were tough times in Germany.

Erich's training years went by smoothly, he went to school in Göttingen, which he finished in 1914. After school he started studying physics. Then, in World War I, he was recruited to help the German military in the department of aerodynamics. Germany lost the war for other reasons, and Erich went back home to finish university. His doctoral thesis (on x-ray diffraction) under physical chemistry bigwig Peter Debye was completed in 1921.

Hard Years, Prolific Years

In the following 16 years Erich went through a difficult period of professional uncertainty. For his scientific work, however, these were his most prolific years. He started out as an assistant to Max Born in Göttingen and worked together with mathematician Dave Hilbert. In 1922 he followed his mentor Peter Debye to Zurich, Switzerland. There he worked on his qualification thesis⁴, on the solvation of electrolytes. This work later lead on to one of the theories that bear Hückel's name: the Debye - Hückel theory. During this period he also published some of his first works on the quantum mechanical description of benzene.

In 1925 Erich married Annemarie Zsigmondy, who was the daughter of chemistry 'top banana' Richard Zsigmondy, who went Nobel in the same year. In 1927 Erich got a grant from the Rockefeller Foundation and was mainly in London for the next two years. He also visited the great Niels Bohr in Copenhagen during that time. It's worth noting, that the whole quantum mumbo-jumbo was a very new concept at that time, and that Niels Bohr, being the quantum chemistry bigwig he was, inspired Hückel to do quantum mechanics on the problem of the chemical double-bond.

Erich's first child, Richard, was born in 1928. In 1930 the Hückel family moved to Leipzig where Erich finished most of the quantum mechanical models he was playing with. Erich did not stay very long in Leipzig. At the end of 1930 he moved to Stuttgart, where he stayed for seven severely underpaid years. In 1931 his second son, Bernhard, was born and in 1933 his third son Manfred. In these years Hückel perfected the so-called Molecular Orbital Theory. It is quite difficult, or irrelevant, to describe what this model is all about in this biography, but let there be the note, that this theory gives some nice information on chemical compounds and is quite fundamental and useful for the understanding of chemical substances. As a nice side effect, it is easy enough for non-physicists, say chemists, to understand.

Ignored and Misunderstood

Maybe no-one paid attention to what Hückel was saying. In the late 1930s Linus Pauling wrote a book about quantum mechanical reasonings concerning the double-bond and the benzene problem using a different (valence bond) approach - this approach is more complicated and a lot less reliable. Linus, however, didn't bother to mention Hückel's work. Hückel got furiously steamed up about this. In his memoirs Hückel wrote:

One can say about Pauling's book [...] that it managed to put science back for 20 years.

In 1937 he became associate professor for theoretical physics in Marburg. Until his retirement in 1962 he did not publish any work with a comparable significance to his previous work (partly, also, because of WW2).

War and Post-war Years

The Nazis didn't like Hückel (and vice-versa). Even with many vacant positions in theoretical physics, resulting from the persecution of Jews, Hückel's promotion was actively blocked. He was not the kind of man to engage in the resistance, but he also refused to chum up with the Nazis. The Nazi period and the first post-war years were full of privations, and hunger. Hückel wrote:

I never got back to the productivity of the early '30s. With 50 in 1946, after the privations of the war period, my memory started fading. It also made no sense to continue [...] working on the problems of benzene.[...] It was not possible for me to follow the innovations in this field, which evolved strongly in England and in the USA.

(Too) Late Recognition

Erich retired from his scientific career silently. Many of his students became relatively well-known professors (in Germany at least⁵). After his retirement the Hückel-Method became more and more widely used in chemistry. The broad implementation of his theory came in the mid-1960s, when Roald Hoffmann (Harvard) used an extension of the Hückel theory (which was now called the 'extended Hückel Theory', or EHT) to calculate chemical reactions. The EHT was in Hoffmann's work, the theoretical basis for the analysis of a certain type of reaction (pericyclic reactions), which until then could not be understood with the standard reaction models.

Using EHT calculations, Roald Hoffmann and Robert Woodward could not only present a mechanistic model for the pericyclic chemical reactions, but also postulate reaction rules for entire families of chemical reactions. These works are today the basis for the understanding of many chemical reactions in organic chemistry. Hoffmann went Nobel in 1981 together with Kenichi Fukui (who used a method similar to the EHT for his calculations). Robert Woodward (who had already received his Nobel chip in 1965) died in the same year. It is possible that Erich Hückel could have been nominated for the Nobel prize in that year. Erich passed away on 16 February, 1980.