用~(119)Sn、~(121)Sb及~(13)C NMR研究无水SnCl_4、SbCl_5与Lewis碱的相互作用

无水SnCl_4及SbCl_5是典型的Lewis酸,是有机反应中常用的催化剂。它们的溶剂化热效应早已受到人们的关注,然而用NMR方法来研究它们的溶剂化作用至今未见报道。本工作用~(119)Sn、~(121)Sb及(13)C NMR考察了典型Lewis酸无水SnCl_4、SnCl_5与二十几种Lewis碱的相互作用,直接证实了Lewis酸碱反应为电子的授受过程。

STUDY ON LEWIS ACID-BASE INTERACTION OF ANHYDROUS SnCl_4 AND SbCl_5 WITH COMMON SOLVENTS BY Sn-119,Sb-121 AND C-13 NMR SPECTROSCOPY

Sn-119,Sb-121 and C-13 NMR study of Lewis acid-base interaction of anhydrous SnCl4and SbCl5with some common solvents is reported. In non-Lewis base solvents , Sn-119 and Sb-121 signals remain unchanged as in neat liquids.In Lewis base solutions , SnCl4 and SnCl, accept electrons from the solvent donor ,and Sn-119 and Sb-121 signals all shift to high field significantly. Some slow exchanging C-13 spectra have been obtained,when coordinated solvent molecules donate electrons to the acceptor , C-13 signals shift to low field. C-13 spectrum of DMF solution of SbCl5 shows evidently that the donating atom is nitrogen and the two methyl signals coincide in coordinated species.