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Alfred Stock

Alfred Stock (1876-August 1946) was a German inorganic chemist.

Born in Danzig (now Gdansk, Poland) and educated at Berlin, he became the director of the Chemistry Department at the Technische Hochschule in Karlsruhe from 1926 to 1936. He was renowned by his pioneer research on chelation in organic metal complexes and pursuing similar chemical properties of carbon in other elements, especially boron and silicon.

Stock began studying the boron hydrides - the boron hydrogen chemical compounds with general formula BxHy - since 1909 at Breslau. Due to their extreme reactivity and flammability in air, separation for characterization of each hydride had not been successful until a high-vacuum separation method was developed in 1912. Similar work was performed on silicon. In 1960s boron hydrides found their first practical use as additives to rocket fuel.

In 1921, he first prepared metallic beryllium by electrolyzing a fused mixture of sodium and beryllium fluorides. This method made beryllium available for industrial use, as in special alloys and glasses and for making windows in X-ray tubes.

He also introduced sensitive tests and devised improved laboratory techniques for dealing with mercury with minimized poisoning risk, possibly initiated by his chronic mercury poisoning in 1923. He became more vocal on protesting the mercury usage after realizing the toxicity of its organic derivatives. German dentistry abandoned his warning in 1928 against copper amalgam usage. Nevertheless a paper from Professor Fleischmann, in which removal of mercury in amalgam-related illness had led to complete recovery, supported his idea. (Deutsche Medizinische Wochenschrift 1928, No. 8). A committee was founded in Berlin to investigate cases of possible mercury intoxication and hence the term micromercurialism was first used.

The term ligand (ligare Latin, to bind) was first used by Stock in 1916. First usage of the term in a British journal was by H. Irving and R.J.P. Williams in Nature, 1948, 162, 746. Monodentate, bidentate, tridentate characterized the number of ligands attached to a metal. Given the introduction of ligand concept, he was also able to further derive the idea of bite angle and other aspects of chelation.

Stock system, first published in 1919, was a means of nomenclature on binary compounds. In his own words, he considered the system to be "simple, clear, immediately intelligible, capable of the most general application." In 1924, a German commission recommended Stock system to be adopted with some accommodations. FeCl2, which would have been named iron(2)-chloride according to Stock's original idea, became iron(II) chloride in the revised proposal. In 1934 Stock agreed to the use of Roman numerals but preferred keeping the hyphen and dropping the parentheses. Although this suggestion has not been followed, the Stock system remains in use worldwide.

After retirement in 1936, he moved from Karlsruhe to Berlin.

He died at Aken an der Elbe, a small town near Dessau, in August 1946 at the age of 70.

original text from geocities by a German

For a fascinating review of the origin and dissemination of the term 'ligand' in chemistry see: W.H. Brock, K.A Jensen, C.K. Jorgensen and G.B. Kauffman, Polyhedron, 2, 1983, 1-7.