The Synthesis and Reactivity of a Molybdenum (IV) Stretched-Dihydrogen Complex

Reaction of [Mo(NPh)(PMe3)3(o-(Me3SiN)2C6H4)] (1) with molecular hydrogen (ca. 1 atm) at -10 degrees C in toluene-d8 results in the formation of dihydrogen complex [Mo(NPh)(PMe3)2(H2)(o-(Me3SiN)2C6H4)] (2) by 1H and 31P NMR spectroscopy. In solution at -50 degrees C 1 and 2 are present in a 1:3 ratio, respectively. The nature of dihydrogen ligand bonding in 2 was probed by T1 analysis and analysis of the JH-D coupling constant in the deuterium hydride isotopomer of 2 giving H-H distances of 1.18 A and 1.17 A, respectively. When allowed to warm to 30 degrees C, 2 reacts affording [Mo(NPh)(PMe3)3(o-(Me3SiN)(NH)C6H4)] (3) over a 1 h period. The X-ray structures of 1 and 3 are reported.