17341-24-1Relevant academic research and scientific papers
Relaxation Kinetics and Infrared Spectra of the Complexation of Lithium Ion by Triethylene Glycol and by Tetraethylene Glycol in Acetonitrile
Cobranchi, Daryl P.,Garland, Ben A.,Masiker, Marilyn C.,Eyring, Edward M.,Firman, Paul,Petrucci, Sergio
, p. 5856 - 5865 (1992)
Ultrasonic absorption relaxation spectra are reported covering the frequency range ca. 1-500 MHz for the complexation of LiClO4 by the open-chain polyethers triethylene glycol (EG3) and tetraethylene glycol (EG4) in acetonitrile at 25 deg C and at a molar ratio R = / or R = / = 1.The ultrasonic spectra can be described by the sum of two Debye relaxation processes which were interpreted according to the Eigen-Winkler mechanism Li+ + EG Li+...EG Li+EG (Li+EG) (where EG denotes either EG3 or EG4), giving the rateconstants k1, k-1, k2, and k-2.The first step is taken to be a preequilibrium step for which K0 is calculated from classical statistical theory.The rate constants are compared with those of the corresponding process involving triglyme and poly(ethylene oxide) (PEO) previously reported.Infrared data for the 3800-3200-cm-1 region show a shift of 70 cm-1 to lower energy, indicating a strong interaction between the ethanolic oxygen of EG3 and the Li+ ion.
Li12Si7, a Compound with Trigonal Planar Si4 Clusters and Isometric Si5 Rings
Nesper, Reinhard,Schnering, Hans Georg von,Curda, Jan
, p. 3576 - 3590 (2007/10/02)
Li12Si7 is the silicon richest compound of the binary system Li/Si, which does not contain a MX phase contrary to the other I-IV systems.Li12Si7 is formed by direct synthesis from the elements.The compound reacts like an alkali metal forming silanes under hydrolysis and amorphous silicon in the reaction with benzophenone (THF), respectively.The metallic grey phase grows in form of orthorhombic rod-shaped crystals (a = 860.0, b = 1975.5, c = 1433.5 pm at 290 K; Pnma, Z = 8).The crystal structure (at 290 K, R = 0.04, and at 140 K, R = 0.02) exhibits two novel Sin clusters, namely a trigonal planar Si4 star and a planar cyclopentadienyl-like Si5 ring (Si-Si = 237.8 and 236.8 pm, resp.) which are enveloped by Li atoms (Li-Si = 259-309 pm).Li12Si7 is a diamagnetic semiconductor (Eg = 0.6 eV), which however does not fulfil in a simple way the classical electron counting rules for Zintl phases.The complicated 3D structure can be separated into two well chosen one dimensional partial structures Li12Si4 and Li6Si5, which allow for a quantum mechanical treatment.The resulting electronic structure gives rise to a reasonable improvement of the Zintl rules for elements of the higher periods.Li6Si5 = Li5(LiSi5) (26e) is in fact an infinite 1D sandwich stack, a lithiosilacen.In the Li12Si4 fragment (28e) a cage orbital occurs, which has amplitudes at all lithium sites.The stabilisation of the CO32- like geometry and the silicon backbone is mainly due this additional state.
