Diverse reactivity of stereoisomers containing quadruply bonded dimolybdenum with oxygen: formation of [{Mo(η-N,N′-diisopropylbenzamidinato)oxo}2(μ-acetato)2(μ-oxo)]

The reaction of quadruply bonded dimolybdenum complex, [Mo2(μ-OAc)4] (1), with lithiated amidinato, Li[(NiPr)2CR] (R = tBu; 2a, Me; 2b, Ph; 2c), was investigated. The reaction of 1 with 2a afforded the dark-red solid, whereas the product was so highly unstable that the product was not able to be characterized. In the case of acetamidinato 2b, lantern-type mixed-ligand quadruply bonded dimolybdenum complex, [Mo2(μ-OAc){μ-(NiPr)2CMe}3] (3), was obtained as a yellow solid. In the reaction with benzamidinato 2c, symmetrical lantern-type dimolybdenum complex, [Mo2(μ-OAc)2 {μ-(NiPr)2CPh}2] (4), was isolated as a yellow solid. In the latter reaction, intermediary red compound (5), which is considered to be stereoisomer of 4 possessing non-lantern-type skeleton, was formed. However, isolation of 5 as a single component was not successful due to isomerization to 4. Complex 5 readily reacted with dry oxygen to give dimolybdenum(V) complex, [{Mo(η-(NiPr)2CPh)oxo}2 (μ-OAc)2(μ-oxo)] (6), as a red solid. These complexes were characterized spectroscopically as well as, in some cases, by X-ray analyses.