Raman spectroscopic characteristics of phthalocyanine and naphthalocyanine in sandwich-type phthalocyaninato and porphyrinato rare earth complexes. Part 3. The effect of rare earth ionic size on the Raman characteristics of naphthalocyanine in bis(naphthalocyaninato) rare earth complexes

Raman spectroscopic data of a series of 13 sandwich double-decker bis(naphthalocyaninato) rare earth complexes M(2,3-Nc*)(2) [M = (CeLu)-Lu-... except Nd and Pm, Y; Nc* = Nc(t Bu)(4)] were collected using laser excitation sources emitting at 632.8 and 785 nm and systematically compared. The Raman characteristics for substituted naphthalocyaninato monoradical anion Nc*(.-) under these two laser excitations are thus comparatively described. The strongly enhanced Raman band at approximately 1592 cm(-1) which is assigned to the naphthalene stretches of the Nc ring, is a typical feature of the monoanion radical, Nc*(.-) under excitation with the 632.8 nm laser line. With laser excitation at 785 nm, which is nearly coincident with the Q band absorption of bis(naphthalocyaninato) rare earth complexes, the band at 1512-1530 cm(-1) due to the C=N (aza group) stretch is a good Raman marker band for the naphthalocyanine anion Nc*(.-). This band and the Nc breathings, naphthalene stretchings, isoindole stretchings, and coupling of pyrrole C=C ring and aza C=N stretches all shift to higher frequency with decreasing ionic radius (the rare earth contraction). (C) 2002 Elsevier Science Ltd. All rights reserved.