The Versatility of Lithium Reagents in Synthetic Organometallic Chemistry: Their differing reactions with [Cp*Mo(NO)(CH2SiMe3)2]
✍ Scribed by Prof. Dr. Peter Legzdins; Prof. Stephen F. Sayers
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 978 KB
- Volume
- 3
- Category
- Article
- ISSN
- 0947-6539
No coin nor oath required. For personal study only.
✦ Synopsis
Cp*Mo(NO)(CH,SiMe,),] exhibits three principal types of reaction with the various lithium reagents investigated during this study, namely: regioselective deprotonation, reduction, and addition. Deprotonation of the reactant, achieved by treatment with lithium amide reagents, leads ultimately to the formation of the alkylidene "ate" complex [Cp*Mo(NO)(CH,SiMe,)( =CHSiMe,)],-[Li,(thf),] (1). While LiN(SiMe,), effects this conversion directly with no detectable intermediates, reaction with 1 equiv of LDA in T H F for 15min deprotonates the Cp* ligand to form the lithium salt of the "tucked-in'' ate complex [(q5,q1-C,Me,CH,)Mo(NO)(CH,SiMe,),l-[Li(thf),] (2) in 40 % isolated yield. Complex 2 slowly converts to the thermodynamically more stable 1 when left as a THF or C,D, solution at ambient tem-perature for 48 h. Reaction of the dialkyl starting material with either tBuLi or PhLi leads to the production of the alkylidene complex 1 in irreproducible yields (10-50% NMR; not isolable). A kinetic analysis of the reaction of [Cp*Mo(NO)-(CH,SiMe,),] with LiN(SiMe,), indicated that the reaction was first-order in both the lithium and molybdenum reagents, and the activation parameters of A H * =7.3+1.Okcdmol-' and A S * = -34 3 e.u. suggest an associative process. Treatment of the neutral dialkyl with 1 equiv of LiPPh, in T H F results in a S * lithium * ic oxidestungsten