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

Abstract

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.

Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

“…The distance between the alkylidene carbon and the lithium center is compatible with a covalent bond. 58,59 Scheme 6. Reactivity of [Ta(CH 2 tBu) 3 IrH 2 (Cp*)], 1, with alkali metal alkyls.…”

Growth and Property Investigations of Two Organic–Inorganic Hybrid Molecular Crystals with High Thermal Stability: 4-Iodoanilinium perchlorate 18-crown-6 and 4-Iodoanilinium Borofluorate 18-crown-6

“…Recently, much attention has been drawn to organic-inorganic hybrid molecular crystals materials [1][2][3][4][5][6][7][8][9][10][11]. These materials are frequently characterized by their various physical and chemical properties, such as structural phase transition, ferroelectric, semiconductor, photovoltaic effect, nonlinear optical response and pyroelectricity, which have potential applications in molecular sensors, switches, data storage, electro optical modulators, light emitting, photo-detector, energy-efficient memories, filtering devices, high-performance insulators and so on [12][13][14][15][16][17][18][19][20][21][22]. Among them, an interesting class is the organic-inorganic hybrid crown type, owing to their large group of structural diversities as well as unique properties (such as dielectric anomaly, ferroelectric, second harmonic generation, nonlinear optical properties, etc.)…”