α-CC agostic structures and aggregation diversity in cyclopropyllithium derivatives

Dufrois, Quentin; Vendier, Laure; Etienne, Michel

doi:10.1039/c6cc02638a

Cited by 8 publications

(9 citation statements)

References 38 publications

(9 reference statements)

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“…As observed for 2, [16] this non-symmetric situation is accompanied by a marked a-CC agostic distortion of the cyclopropyl group A with Li1. Indeed, the structure of 3 presents a conspicuously acute LiÀCaÀCb angle [Li1ÀC1ÀC2 79.47(13)8 vs. Li2ÀC1ÀC3 114.62(13)8] together with a short Li···Cb distance [Li1···C2 2.392(4) ] and an elongated Ca À Cb bond [C1 À C2 1.561(2) vs. C1 À C3 1.524 (2) ].…”

Section: Angewandte Chemiesupporting

confidence: 61%

“…Up to now there are only two examples of tetramers crystallizing as squares, unknown for unsupported Li + (Scheme 1, below): 1) a benzyllithium derivative, where the lithium cations are coordinated to a bidentate O,N-donor base in [{m-CH 2 Ph}Li-{k 2 -Me 2 N(CH 2 ) 2 OMe}] 4 , [14] and 2) an aryllithium derivative, 2,4,6-tri(isopropyl)phenyllithium in which lithium-p-arene interactions complement the Li À C s-bonds. [15] Capitalizing on previous work on [Li(thf) 2 (m-c-CPhC 2 H 4 ) 2 Li(thf)], [16] we now report that seemingly weaker secondary interactions in the form of CC agostic interactions may support Lewis basefree two-coordinate lithium cations in cyclopropyl derivatives arranged as a square in [{m-c-C(SiMe 3 )C 2 H 4 }Li] 4 .…”

supporting

confidence: 59%

“…The importance of CC agostic interactions was further investigated when 1-(phenylthio)cyclopropyllithium was synthesized. This target was chosen as it bears similarities with both the recently reported [16] a-CC agostic 1-phenylcyclopropyllithium [Li(thf) 2 (m-c-CPhC 2 H 4 ) 2 Li(thf)] 2 and 1. With a soft S atom in the a-position, there is the potential for intramolecular coordination to a hard lithium cation-which could compete with a CC agostic interaction.…”

Section: Angewandte Chemiementioning

confidence: 99%

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Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives

Dufrois

Daran

Vendier

et al. 2017

Angew. Chem. Int. Ed.

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Understanding and controlling the aggregation state is germane to alkyllithium chemistry. Lewis base-free alkyllithium compounds normally form tetrahedral tetramers or octahedral hexamers in the solid state with the lithium cations being three-coordinate. We report that the unsupported cyclopropyl derivative 1-(trimethylsilyl)cyclopropyllithium [{μ-c-C(SiMe )C H }Li] (1), synthesized by the reduction of 1-(phenylthio)-1-(trimethylsilyl)cyclopropane, crystallizes as a tetramer in the space group I-4 with the two-coordinate lithium atoms forming a square. CC agostic interactions complete the coordination sphere around each lithium. The aggregate is preserved in hydrocarbon solution. Furthermore, CC agostic interactions compete intra- and intermolecularly with Lewis base donation as in the unsaturated dimer of 1-(phenylthio)cyclopropyllithium [Li(thf) {μ-c-C(SPh)C H } Li (thf)] (3) which is also fully characterized.

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Section: Angewandte Chemiesupporting

confidence: 61%

supporting

confidence: 59%

Section: Angewandte Chemiementioning

confidence: 99%

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Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives

Dufrois

Daran

Vendier

et al. 2017

Angew. Chem. Int. Ed.

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show abstract

“…Up to now there are only two examples of tetramers crystallizing as squares, unknown for unsupported Li + (Scheme , below): 1) a benzyllithium derivative, where the lithium cations are coordinated to a bidentate O,N‐donor base in [{μ‐CH 2 Ph}Li{κ 2 ‐Me 2 N(CH 2 ) 2 OMe}] 4 , and 2) an aryllithium derivative, 2,4,6‐tri(isopropyl)phenyllithium in which lithium‐π‐arene interactions complement the Li−C σ‐bonds . Capitalizing on previous work on [Li(thf) 2 (μ‐ c ‐CPhC 2 H 4 ) 2 Li(thf)], we now report that seemingly weaker secondary interactions in the form of CC agostic interactions may support Lewis base‐free two‐coordinate lithium cations in cyclopropyl derivatives arranged as a square in [{μ‐ c ‐C(SiMe 3 )C 2 H 4 }Li] 4 .…”

Section: Methodsmentioning

confidence: 99%

Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives

et al. 2017

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Understanding and controlling the aggregation state is germane to alkyllithium chemistry. Lewis base‐free alkyllithium compounds normally form tetrahedral tetramers or octahedral hexamers in the solid state with the lithium cations being three‐coordinate. We report that the unsupported cyclopropyl derivative 1‐(trimethylsilyl)cyclopropyllithium [{μ‐c‐C(SiMe3)C2H4}Li]4 (1), synthesized by the reduction of 1‐(phenylthio)‐1‐(trimethylsilyl)cyclopropane, crystallizes as a tetramer in the space group I‐4 with the two‐coordinate lithium atoms forming a square. CC agostic interactions complete the coordination sphere around each lithium. The aggregate is preserved in hydrocarbon solution. Furthermore, CC agostic interactions compete intra‐ and intermolecularly with Lewis base donation as in the unsaturated dimer of 1‐(phenylthio)cyclopropyllithium [Li(thf)2{μ‐c‐C(SPh)C2H4}2Li (thf)] (3) which is also fully characterized.

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“…Quantum chemical calculations are valuable tools to elucidate the agostic and π-interactions between the s-block metal ions and multiple bonds [25,26]. Isoelectronic ion pairs such as Na + /Mg 2+ , K + /Ca 2+ /Sc 3+ , Rb + /Sr 2+ /Y 3+ , and Cs + /Ba 2+ /La 3+ allow one to deduce the influence of electronegativity, size and hardness on reactivity and bonding parameters.…”

Section: Toxicity Of Elementmentioning

confidence: 99%

Kudos and Renaissance of s-Block Metal Chemistry

Krieck¹,

Westerhausen²

2017

Inorganics

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Abstract:In recent years, the organometallic and coordination chemistry of the alkali and alkaline earth metals has experienced tremendous progress to tackle the needs of today's society. Enhanced ecological awareness and global availability favor research on the chemistry of the essential s-block metals. Nowadays, the s-block metals are conquering new chemical fields based on sophisticated theoretical and preparative achievements. Recent investigations show a huge impact of the s-block elements on stoichiometric and catalytic processes.Keywords: s-block metals; catalysis; Grignard reagents; alkali metals; alkaline earth metals The s-block metals subsume the elements of the first two groups of the periodic table-the alkali and alkaline earth metals. The non-radioactive elements were all discovered by the middle of the 19th century [1] (Table 1), initiating a profound s-block metal-based chemistry with a very long tradition. Generally, the toxicity is low and highly toxic congeners are limited to the radioactive metals and beryllium [2], justifying the underrepresented extent of their chemistry.

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α-CC agostic structures and aggregation diversity in cyclopropyllithium derivatives

Cited by 8 publications

References 38 publications

Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives

Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives

Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives

Kudos and Renaissance of s-Block Metal Chemistry

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