Diversity of Catalysis by an Imido-Hydrido Complex of Molybdenum. Mechanism of Carbonyl Hydrosilylation and Silane Alcoholysis

Abstract

New Imido hydride complex 1 catalyzes a variety of silylation reactions that proceed via initial substrate activation but not silane addition.

Catalytic hydroboration by an imido-hydrido complex of Mo(iv)

“…9 However, no transfer hydrogenation was observed in reactions of 3 with acetone or acetophenone even upon heating up to 60 1C. Such a difference in the reactivity of 3 towards aldehydes and ketones allows us to explain the difference in chemoselectivity of the stoichiometric reactions of 1 with 4-acetylbenzonitrile and 4-formylbenzonitrile to give 5 and 7, respectively.…”

“…8 We have recently reported catalytic and mechanistic studies on hydrosilylation reactions mediated by the imido-hydrido complex (ArN)Mo(H)(Cl)(PMe 3 ) 3 (1; Ar = 2,6-i Pr 2 C 6 H 3 ), including one of the first examples of nitrile hydrosilylation. 9 Believing that HBCat may exhibit even superior reactivity patterns due to its enhanced Lewis acidity, we elected to study the hydroboration catalysed by 1. Here we report the results of these efforts, including an insight into the mechanism and observation of unusual B-HÁ Á ÁM agostic and borylimino intermediates.…”

“…The 1 H NMR spectrum of 11 revealed an upfield imine proton at 5.00 ppm (dd, 3 J H-P = 3.1 Hz), diagnostic for the Z 2 -NQCHPh moiety, which is further supported by a significant upfield shift of the 13 C NMR resonance for the imine carbon (62.9 ppm, found by as in the parent complex 1. 9 The downfield 11 B NMR signal at 10.1 ppm indicates a 3-coordinate boron.…”

Coordinatively Saturated Tris(oxazolinyl)borato Zinc Hydride-Catalyzed Cross Dehydrocoupling of Silanes and Alcohols

“…To provide further support for the proposed mechanism, the concentrations of species in the catalytic reactions were monitored by 1 6 .…”

Reduction of Aromatic and Aliphatic Esters Using the Reducing Systems MoO2(acac)2 or V(O)(OiPr)3 in Combination with 1,1,3,3‐Tetramethyldisiloxane

“…Since then, other molybdenum complexes have been employed for hydrosilylation. [36,37,38] In our laboratory, TMDS has already been employed to efficiently reduce a range of functions such as phosphane oxides, [39] nitriles, [40] amides, [41] nitro, [42] acetals, [43] and ketones [44] depending on the nature of the metal catalyst. We report herein a new method for the reduction of aromatic or aliphatic esters into alcohols using TMDS as reducing agent in association with two different metal sources to compare their reactivity.…”