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Infrared Spectra of Phthalocyanine and Naphthalocyanine in Sandwich-Type (Na)phthalocyaninato and Porphyrinato Rare-Earth Complexes. II. The Effects of Rare-Earth Ionic Size on the IR Characteristics of Naphthalocyaninein Bis(naphthalocyaninato) Rare-Earth Complexes
X. Sun, M. Bao, N. Pan, X. Cui, D. P. Arnold and J. Jiang
Abstract
The infra-red (IR) spectroscopic data for a series of 28 homoleptic substituted bis(naphthalocyaninato) rare-earth complexes M(2,3-Nc*)2 [M = Y, La–Lu except Pm; H2Nc* = 3(4),12(13),21(22),30(31)-tetra(tert-butyl)-2,3- naphthalocyanine (H2TBNc) and 3,4,12,13,21,22,30,31-octa(dodecylthio)-2,3-naphthalocyanine (H2ODTNc)] have been collected with a resolution of 2 cm–1. These neutral sandwich complexes are radicals due to their composition (Nc*)2–MIII(Nc*)–, wherein the unpaired electron is delocalized over both macrocycles on the vibrational time scale. Compared to spectra obtained with low resolution, such as 4 cm–1, a larger number of vibrational modes could be distinguished. The IR spectra for M(ODTNc)2 are much simpler than those of M(TBNc)2, revealing the relatively higher symmetry of the former molecules. By analogy with bis(phthalocyaninato) rare-earth counterparts, the pyrrole stretching absorptions at 1314–1317 and 1323–1330 cm–1 for M(TBNc)2 and at 1316–1327 cm–1 for M(ODTNc)2 are assigned to the IR marker bands of the respective naphthalocyanine mono-anion radicals. These marker bands, together with those at 746–753 cm–1 assigned to C–H wagging, 1350–1355 cm–1 attributed to pyrrole stretchings, and 1389–1394 cm–1 due to naphthalene stretchings, have been found to shift slightly to higher energy along with the rare-earth contraction, clearly demonstrating the effect of rare-earth ionic radius.
Australian Journal of Chemistry 55(9) 587 - 595 (2002) doi:10.1071/CH02080
