Practising organometallic chemistry in nineteenth century Australia: David Orme Masson and diethyl magnesium

Abstract

By the late 1880s, the existence of alkyl derivatives of metals such as zinc and mercury was well established but diethyl magnesium had been poorly characterised and obtaining proof of its existence was a reasonable aim for chemists. Professor David Orme Masson and his student, Norman Wilsmore, at the university in the British colonial capital, Melbourne, accepted the challenge despite their distance from northern hemisphere centres of chemical research. The ‘tyranny of distance’ was tempered by their access to chemical journals and textbooks and by Masson’s connections at the ‘centre’, notably with William Ramsay. Wilsmore repeated the earlier experiments and also used methods that had been successful with other metals, but was unable to prepare diethyl magnesium. Masson rationalised this failure on the basis of the element’s position in the periodic classification of the elements that Mendeleev and Lothar Meyer had published, and on magnesium’s position on the atomic volume curve of Meyer, and concluded that diethyl magnesium could not exist. The weakness of these arguments was revealed when, near-coincidentally with Masson’s and Wilsmore’s publication of the results of their experiments, Philippe Löhr, working in Meyer’s laboratory, published successful syntheses of several alkyl magnesium derivatives by methods that had been unsuccessful in Wilsmore’s hands. Masson’s heuristic use of Meyer’s curve was unusual, and a notable feature of his approach to chemistry.