A Quest for Ligand-Unsupported Li plus -p Interactions in Mono-, Di-, and Tritopic Lithium Arylborates

作者：Franz Daniel; Ilkhechi Alireza Haghiri; Bolte Michael; Lerner Hans Wolfram; Wagner Matthias^*

来源：European Journal of Inorganic Chemistry, 2011, (35): 5414-5421.

DOI：10.1002/ejic.201100824

• Lithium
• Polyanions
• Borates
• Bridging ligands
• Coordination modes

The lithium salts of selected mono-, di-, and tritopic arylborates have been synthesized and their solid-state structures have been analyzed by X-ray crystallography with focus on the occurrence of Li+aryl p interactions. The solvated salts of the monotopic arylborate [Li(thf)4][(p-BrC6H4)BPh3] as well as the ditopic borates [Li(12-crown-4)2]2[p-C6H4(BMe3)2] and [Li(tetraglyme)]2[p-C6H4(BPh3)2] exist as solvent-separated ion pairs in the crystal lattice. The attachment of two moderately coordinating monohydridoborate functionalities on a benzene ring leads to Li+hydride interactions. In the case of [Li(thf)3]2[p-C6H4{9-BBN(H)}2] [9-BBN(H) = 9-borabicyclo[3.3.1]nonane], this additional attractive force is not sufficient to promote Li+aryl p interactions, however, the 1,2-dimethoxyethane (DME) solvate [Li(dme)2]2[p-C6H4{9-BBN(H)}2] shows a remarkably short contact between the Li+ cation and the adjacent phenylene ipso carbon atom [LiC 2.366(2) angstrom]. The targeted structural motif ofLi+arene ?6 coordination was finally observed in the solid-state structures of the tritopic borates [{Li(12-crown-4)2}2Li(thf)][1,3,5-C6H3(BMe3)3] and [{Li(thf)2}2Li][1,3,5-C6H3(BH3)3]. In the latter complex, an extensive network of LiHB bonds is observed in addition to the Li+p interaction.

• 出版日期2011-12