Infra-red studies on charge-transfer complexes. Part 1.—A comparison of the vibrational intensities of pyridine with those of pyridine-ICl

Abstract

Integrated infra-red intensity meaurements are reported for the vibrational fundamental bands of pyridine and of the pyridine-ICl charge-transfer complex in chloroform and benzene solutions. An attempt has been made to interpret the large intensity changes which occur on complexation in terms of the charge-transfer model proposed by Mulliken. Intensity perturbations arise in addition to those expected for the “weak” complex approximation and several interesting anomalies in the intensity data are discussed.