[(thf)Li2{H2CS(NtBu)2}]2: Synthesis, Polymorphism, and Experimental Charge Density to Elucidate the Bonding Properties of a Lithium Sulfur

详细信息    查看全文

• 作者：Stephan Deuerlein ; Dirk Leusser ; Ulrike Flierler ; Holger Ott ; Dietmar Stalke
• 刊名：Organometallics
• 出版年：2008
• 出版时间：May 26, 2008
• 年：2008
• 卷：27
• 期：10
• 页码：2306 - 2315
• 全文大小：1208K
• 年卷期：v.27,no.10(May 26, 2008)
• ISSN：1520-6041

文摘

Sulfur ylides (RB>2S⁺−⁻CR₂) are widely used in organic synthesis for stereoselective epoxidations, cyclopropane formations, and ring expansion reactions. Nevertheless, their electronic properties are still under debate, because their ylenic textbook formulation (R₂S<img src="http://pubs.acs.org/images/entities/dbd_2.gif">CR₂) contradicts the reactivity. In order to elucidate the electronic situation in a sulfur ylide, we present an experimental charge density study via multipole refinement and subsequent topological analysis based on high-resolution X-ray data of [(thf)Li₂{H₂CS(N^tBu)₂}]₂ (1). The title compound is of special interest, since additionally the formal hypervalency can be investigated along with the controversial interaction between a carbanion with a Li₃ triangle. As a prerequisite for these studies, the polymorphism and synthesis of 1 were investigated. The findings clearly support the ylidic, non-hypervalent description of the molecule. The ylidic carbanion was determined to be 6-fold coordinated with three single bonds to the sulfur atom and both hydrogen atoms and three closed-shell interactions to the lithium atoms of the Li₃ triangle.