锂盐冠醚络合物的红外光谱研究

INFRARED SPECTRA OF CROWN ETHER COMPLEXES OF LUTHIUM SALTS

制备了两种新的锂盐冠醚络合物:LiBr·(15-C-5)·H_2O和LiTFA·(18-C-6)·3H_2O。测定了二种锂盐LiCl、LiBr的(15-C-5)络合物和四种锂盐LiCl、LiBr、LiClO_4LiTFA的(18-C-6)络合物的中红外光谱,对主要吸收峰进行了指认,表明各种锂盐上的Li^+都直接与醚环上的氧络合。由于不同锂盐的配位水形成氢键的差异,锂盐(15-C-5)络合物中配位的V_(OH)波数大小顺序为,LiClO_4>LiCl>LiBr,而锂盐(18-C-6)络合物中配位的V_(OH)波数大小的顺序为LiClO_4>LiTFA>LiBr>LiCl。此外,LiTFA盐中TFA^-的构型属Cs点群,呈双齿配体,但与Li^+配位后,由于构型变化,发生谱带分裂和频率移动。

Two new complexes, LiBr·(CH_2CH_2O)_5·H_2O and CF_3COOLi·(CH_2CH_2O)_6·3H_2O, wereprepared and their in frated spectra(400 - 4000cm^(-1))were examined. The infrared study includeda similar (CH_2CH_2O)_5 complex of LiCl, and also similar (CH_2CH_2O)_6 complexes of LiCl,LiBr and LiClO_4, but with 5H_2O, 5H_2O and 2THF·3H_2O respectively. Assignment of thevarious absorption bands was performed. Evidence was found for the splitting of the OHband due to two different modes of dentation(bridge and terminal) of the water molecule,and also for the splitting of the FCF_2 and OCO bands due to the conformational transfor-mation of CF_3COO^- while entering coordination.