Solid-State and Theoretical Model Structures of Monolithiated (Organosulfonyl)acetonitriles and the Characterization and Reactivity of Their Geminated Dilithio Derivatives
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- 作者：Kenneth W. Henderson ; Alan R. Kennedy ; Dugald J. MacDougall ; and David Shanks
- 刊名：Organometallics
- 出版年：2002
- 出版时间：February 18, 2002
- 年：2002
- 卷：21
- 期：4
- 页码：606 - 616
- 全文大小：184K
- 年卷期：v.21,no.4(February 18, 2002)
- ISSN：1520-6041
文摘
Two monolithiated (organosulfonyl)acetonitriles [PhSO2CHCNLi·TMEDA], 1, and [t-BuSO2CHCNLi·THF], 2, have been synthesized and, in turn, characterized in the solid state byX-ray crystallography. The complexes form novel chain and sheet polymeric structures inpreference to the more common (SO2Li)2 or Li2N2 ring dimers associated with lithiatedsulfones or nitriles. The X-ray crystal structures of the parent ligands RSO2CH2CN, whereR = Ph 5 or t-Bu 6, were also elucidated to allow a direct evaluation of the effects ofmetalation on the bonding within the complexes. Ab initio calculations at the HF/6-31G*level of theory support the view that the simple dimers are not formed due to the inflexibilityof the ligand backbone, precluding chelation and consequently destabilizing these structures.In contrast, polymer formation allows the metal to bridge between separate ligands,eliminating the need for internal chelation. Both 1 and 2 contain "naked" anions wherethere is no direct bond between the anionic C atoms and the metal centers. The anionic Catom in 2 is essentially planar, whereas in 1 this center is distinctly pyramidylized. Crystalstructure and solution 1H and 13C NMR data, in combination with ab initio (HF/6-31G*)and density functional (B3LYP/6-31++G**) calculations on model systems, indicate thatboth the sulfonyl and the nitrile units of the ligands participate in delocalizing the chargeof the anions throughout the S
CC
N linkage. In addition, the dilithiated salts [PhSO2CCNLi2·THF], 3, and [t-BuSO2CCNLi2·0.75THF], 4, have been prepared by the reaction of2 equiv of MeLi with 5 or 6 in THF solution. Both complexes have been characterized by 1Hand 13C NMR spectroscopy and found to be authentic geminal organodimetallic species, withthe methylene group being doubly deprotonated. Complexes 3 and 4 react cleanly with excessMeI to form the dialkylated products PhSO2CMe2CN, 7, and t-BuSO2CMe2CN, 8, respectively,in a single step.
CCN linkage. In addition, the dilithiated salts [PhSO2CCNLi2·THF], 3, and [t-BuSO2CCNLi2·0.75THF], 4, have been prepared by the reaction of2 equiv of MeLi with 5 or 6 in THF solution. Both complexes have been characterized by 1Hand 13C NMR spectroscopy and found to be authentic geminal organodimetallic species, withthe methylene group being doubly deprotonated. Complexes 3 and 4 react cleanly with excessMeI to form the dialkylated products PhSO2CMe2CN, 7, and t-BuSO2CMe2CN, 8, respectively,in a single step.