The results of a Raman study of liquid NH3, ND3, and ND3H and of Nal and NaC104 solutions in liquid NH3 are reported. The resolution of the experimental envelopes in the N-H and N-D stretching regions suggests a two-species model for the solvent structure. Band positions for the pure liquids and solutions at different temperatures are discussed in terms of the proposed liquid structure model.
correct, its ESR spectrum should have #u and g, values comparable to the electronically analogous We would also anticipate that such a species should exhibit marked solvent dependence in both its ESR spectrum and its electrochemistry because of the presence of an unpaired electron in the z2 orbital. Indeed it is most likely to be fivecoordinate (low-spin d7, cf. Pc2_FeIS3b). The ESR spectrum of the dianion is in fact very similar to that of the six-coordinate low-spin d6 Pc2"Mnn precursor. The reversibility observed in the electrochemistry of this species and the absence of any following reaction led us to assume that the coordination number probably remains six with two coordinated solvent molecules. The species is therefore assigned as Pc4~MnnS2.
ConclusionWithin the range studied, the manganese phthalocyanine system gives rise to the species [Pc~MnmS2]2+, [Pc2"MnmS2]+, Pc2"MnnS2, Pc3"MnIIS2]', and [Pc4-MnnS2]2\ where in the case of the manganese(III) species, a solvent molecule may be displaced by an anion X. No evidence of manganese (I) was observed in distinction to the iron and cobalt series.3,17The electron-transfer rates of the PcMn11 electron-transfer steps are similar in magnitude to those usually found in analogous porphyrin series.24 Unlike (TPP)MnIUCl, however, the rate is not profoundly changed by either choice of anion or coordinating ligands. The Pc2~Mnm/Pc2~Mnn couple appears at a slightly more anodic potential than in the porphyrin (24) Kadish.'K. M.; Davis, D. G. Anal. N.Y. Acad. Sci. 1973, 206, 495. series. Reduction of the phthalocyanine ring, however, to form [Pc3~MnnS2]~appears 0.5-0.8 V anodic of the corresponding porphyrin reduction.25 These trends are consistent with earlier views of the comparative electrochemistry of porphyrins and phthalocyanines.3,26 This comparison illustrates the variation in coordination electronic and geometric structure accessible within the MN4 class of compounds and its effect upon electrochemical properties.Acknowledgment. This is part of a joint investigation with Professor A. J. Bard (The University of Texas at Austin) supported by the U.S. Office of Naval Research, to whom we are indebted. We also thank the Natural Science and Engineering Research Council (Ottawa) for financial support. Finally, we thank Dr. S. Ma for the donation of a sample of (tetra-Zerf-butylphthalocyaninato)manganese(III) hydroxide.
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