Author(s): Errington RJ; Clegg W; Tombul M; Coxall RA
Abstract: The title compound, bis(borato)dodeca(tert-butoxo)octadecalithium, [Li18(BO3)2(C4H9O)12], is formulated conveniently as [{(tBuOLi)3(Li3BO3)}2(tBuOLi)6]. A central 12-membered ring and two outer six-membered rings are formed by alternating Li+ cations and alkoxide O atoms. Sandwiched between the central ring and each of the outer rings is a planar array of three further Li+ cations surrounding a [BO3]3- anion. Thus, the molecule consists of a cationic [Li18(OtBu)12]6+ cage encapsulating two borate anions. This compound is the first example of a structurally characterized polynuclear lithium borate, and a rare case of a lithium alkoxide cage with nuclearity greater than eight. All the alkoxide ligands are triply bridging, and the lithium ions have trigonal-planar, trigonal-pyramidal and fourfold coordination, all with major distortions from regular coordination geometry.
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Dr John Errington
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