Alwyn George Davies. 13 May 1926 — 1 September 2023

Alwyn Davies was one of the last surviving members of Christopher Ingold (FRS)'s research group, a set of chemists who together transformed our understanding of mechanistic organic chemistry and laid the foundation for modern teaching of the subject. His early independent research on organic peroxides led into organometallic peroxides and thence into organometallic chemistry. His monographs Organic peroxides (1961, Butterworths) and Organotin chemistry (1997, 2004, Wiley) helped to promote the rapid growth of these topics. One route to organometallic peroxides was the reaction of organometallic compounds with dioxygen, and Alwyn Davies showed that these reactions occurred by a free radical chain reaction. Perhaps his greatest contribution was to establish that radical reactions would often occur at the metal centres in main group organometallic compounds, sometimes a million times faster than at hydrogen. He used electron spin resonance (ESR) spectroscopy to monitor the products and rates of these reactions, and to study the properties of the organic radicals that were produced. The theme of metals behaving as hydrogen surrogates permeated much of the work. In his later career, he developed improved methods for generating organic radical cations, and he recorded and analysed their unusual ESR spectra.