Unique µ-Arene-dimolybdenum Complexes with a Mo–Mo Multiple Bond

Abstract

Novel dimolybdenum complexes bridged with aromatic rings (toluene, anisole), [Mo2(L')2(C7H8)] (1C7H8) and [Mo2(L')2(C7H8O)] (1C7H8O), have been synthesized and characterized by FT-IR and X-ray analysis. Their X-ray structures revealed that the two molybdenum ions were bridged with aromatic rings in unique cis-µ-η2(1,2):η2(4,5) or cis-µ-η2(2,3):η2(5,6) mode to form a Mo–Mo bond; 2.1876(5) and 2.1867(5) Å for 1C7H8 and 2.1886(11) and 2.1904(11) Å for 1C7H8O, respectively. The metal-bound carbon atoms of the bridged aromatic rings were deviated toward the metal atoms from the mean plane and the C–C bonds were shortened and elongated alternately. Judging from the valences of molybdenum ions and the short metal–metal bond distances, it is concluded that the two molybdenum ions are formed a quadruple bond, and also suggested that this bond distance is shortened by µ-arene molecules linked with the electron-releasing substituent group.