Tetra acetato dimolybdenum II

Submitted by RICHARD A. WALTON, PHILLIP E. FANWICK, and GREGORY S. GIROLAMf 

In 1960, Wilkinson discovered that several carboxylic acids, HO2CR, react with molybdenum hexacarbonyl, Mo(CO)e, at elevated temperatures to form complexes of the type Mo(02CR)2 . The tme nature of these bright yellow molyb-denum(II) complexes was established in 1964 with the publication by Lawton and Mason of the X-ray crystal stmcture of tetra(acetato)dimolybdenum, which is depicted schematically in Fig. 1The Mo—Mo distance of 2.11A is considerably shorter than the Mo—Mo distance of 2.78 A in molybdenum metal, and this fact is evidence that the Mo—Mo bond in Mo2(02CCH3)4 has considerable multiple bond character. 

In fact, because Mo(II) is isoelectronic with Re(III), Cotton proposed that Mo2(02CCH3)4 contains a molybdenum-molybdenum quadruple bond. A vast 

Department of Chemistry, Purdue University, West Lafayette, IN 47907. 

Inorganic Syntheses, Volume 36, First Edition. Edited by Gregory S. Girolami and Alfred P. Sattelberger. 

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