Zhou, Wen and Platel, Rachel H. and Tasso, Thiago Teixeira and Furuyama, Taniyuki and Kobayashi, Nagao and Leznoff, Daniel B. (2015) Reducing zirconium(IV) phthalocyanines and the structure of a Pc4-Zr complex. Dalton Transactions, 44 (31). pp. 13955-13961. ISSN 1477-9226
Full text not available from this repository.Abstract
The synthesis and characterization of the ring-unsubstituted zirconium phthalocyanine PcZrCl2 (1; Pcx- = phthalocyaninato(x-)) and its reduction products are described. X-ray analysis of 1 (crystallized from hot 1-chloronaphthalene) reveals that 1 is a chloride-bridged dimer [PcZrCl](2)(mu-Cl)(2) in the solid-state; 1 was also characterized by UV-vis/MCD spectroscopy and cyclic voltammetry, which indicated reduction potentials at -0.55, -0.95 and -1.28 V. Although attempts to access these Pc-ring reduced species with KC8 led to mixtures of reduced products due to the insolubility of both starting materials, one equivalent of the reducing agent KEt3BH reacted with 1 to generate Pc3--containing species, as indicated by visible Q-band spectral changes (from lambda(max) = 686 for 1 to 589/611 nm), a single ESR peak (g = 2.001) and paramagnetically shifted H-1 NMR resonances consistent with the presence of a Pc-radical anion. Addition of two equivalents of KEt3BH to 1 generated Pc4--containing species, confirmed by a shift in lambda(max) to 522 nm and upfield-shifted H-1 NMR peaks relative to 1. Reaction of 1 with one and two equivalents of LiCp* did not generate Cp*-substituted products but also effected reduction to analogous Pc-3 and Pc-4 species. This latter material, the air-sensitive ring di-reduced "ate"-complex Pc4-Zr(LiCl)(1.5)(DME)(3), of the form [LiCl(DME)(4)](0.5)[Pc4-ZrClLi(DME)] was structurally characterized, illustrating partial bond localization in the Pc4- ring, which also adopts a saddle-shape vs. the more typical dome-configuration found in 1. This represents a rare example of an isolated and structurally characterized Pc4- complex.