This refers to the metal-metal distances in the element, as far as possible in environments in which the metal is 12-coordinate and at or near ambient temperatures.
Notes
Some other data is taken direct from the primary literature.
Literature sources
G.W.C. Kaye and T.H. Laby in Tables of physical and chemical constants, Longman, London, UK, 15th edition, 1993.
W.W. Porterfield in Inorganic chemistry, a unified approach, Addison Wesley Publishing Co., Reading Massachusetts, USA, 1984.
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