Who was the inventor of the 18-electron rule?

Question

According to Wikipedia, the first person who proposed 18-electron rule was American chemist Irving Langmuir, but the rule is widely known by the name Sidgwick's rule. I cannot find any information about Sidgwick, was he a scientist?

Answer 1

History of the rule is traced in Jensen, The Origin of the 18-Electron Rule. Langmuir proposed the original version in Types of Valence (1921). Nevil Sidgwick (1873-1952) refined it using Bohr-Bury configurations in 1923, see his Electronic Theory of Valency (1927).

Detailed Sidgwick's biography is available from the Royal Society. He was born in Oxford on 8 May 1873. In 1892 he entered Christ Church college at Oxford to study natural sciences, and in the late 1890-s worked in Ostwald’s laboratory in Leipzig, where he learned modern techniques of studying organic compounds. From 1901 and for the rest of his life Sidgwick stayed in the Lincoln college. In 1914 he met Rutherford, whose work and personality had a deep influence on him. From then on he turned to atomic chemistry. Aside from the 18-electron rule, he is remembered for the inert-pair effect (1927) and ideas that led to the VSEPR theory (1940).

Here is from Jensen:

"The 18-electron rule, much beloved of the organometallic chemist, was first formulated in 1921 by the American chemist, Irving Langmuir (1881–1957), as part of his program to extend the Lewis static-atom model beyond argon in the periodic table... An alternative electron counting procedure, based on the newer electronic configurations of Bohr and Bury, was introduced by the British chemist, Nevil Sidgwick (1873– 1952), in 1923. Known as the effective atomic number (EAN) rule, it focused not just on the valence-shell electron count, but on the total atom electron count. Attainment of an octet or an 18-electron outer configuration was equivalent to attaining the total electron count (or atomic number) of the nearest noble gas.

Sidgwick’s counting procedure was first applied to transition-metal carbonyls and nitrosyls by the German chemist, F. Reiff, in 1931; in 1934 Sidgwick extended its use to include bridged, as well as mononuclear, complexes. By 1940 Blanchard was also using Sidgwick’s version of the rule and the same is true of many inorganic texts published in the 1950s. In the late 1960s, however, there was a reversion to the earlier electron counting procedure of Langmuir, no doubt because Sidgwick’s procedure, which includes the chemically inactive core electrons, results in a separate numerical stability standard for each row of the transition block, whereas Langmuir’s procedure, like the octet rule, makes use of a single numerical standard applicable to the entire block."

Answer 2

I imagine the reference is to Nevil Sidgwick The Wiki entry does not specifically mention that rule but he clearly worked in related areas. Note that scientific discoveries are often named after someone other than their discoverer, a phenomenon known as Stigler's law of eponymy