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Structural Chemistry of Lithium Tetrahydroborate Ether Solvates ☆
Author(s) -
Giese HansHermann,
Nöth Heinrich,
Schwenk Holger,
Thomas Steffen
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199807)1998:7<941::aid-ejic941>3.0.co;2-y
Subject(s) - chemistry , molecule , dimethoxyethane , crystallography , ether , lithium atom , lithium (medication) , dimethyl ether , crystal structure , hydrogen bond , stereochemistry , ion , organic chemistry , methanol , medicine , electrode , electrolyte , ionization , endocrinology
LiBH 4 · OEt 2 ( 1 ) and LiBH 4 · O(Me)CMe 3 ( 2 ) form double‐stranded chains in the solid state. While 3 hydrides of the BH 4 group in 1 bind to three different Li atoms through Li···H–B interactions, the fourth H atom interacts with three adjacent Li centers. In contrast, in compound 2 there are two single Li···H–B bonds and two doubly bridging hydrogen atoms, the latter again interacting with three lithium centers. Moreover, the arrangements of the ether molecules in 1 and 2 are different. LiBH 4 · 2 DME ( 3 ) (DME = dimethoxyethane) forms a molecular lattice, in which the BH 4 – anions are present in Li···H 2 BH 2 bridges. The same structural feature is present in LiBH 4 · TG ( 4 ) (TG = triglyme = triethylene glycol dimethyl ether), but the TG molecule coordinates to two Li centers through two of its four oxygen atoms in such a manner that a chain structure results. The compound LiBH 4 · 3 THF ( 5 ) exists as discrete molecules in the lattice. Its BH 4 – anion is triply bridging to the Li center. In contrast, LiBH 4 ·C 3 H 6 O 2 ( 6 ) (1,3‐dioxolane) is polymeric. Due to the presence of two μ 2 2 ‐BH 4 groups, a chain of the type ···Li(H 2 BH 2 )Li(H 2 BH 2 )··· is formed, and the 1,3‐dioxolane molecules connect the chains through Li–O coordination to form a three‐dimensional array. In spite of the variations in the bonding of the BH 4 group to Li centers, the Li atoms are hexacoordinated in 3 to 6 but are heptacoordinated in 1 and 2 .