TERVALENT-METAL PORPHYRIN-PHTHALOCYANINE HETEROLEPTIC SANDWICH-TYPE COMPLEXES - SYNTHESIS, STRUCTURE, AND SPECTROSCOPIC CHARACTERIZATION OF THEIR NEUTRAL, SINGLY-OXIDIZED, AND SINGLY-REDUCED STATES

摘要

The synthesis and spectroscopic properties of the neutral metal(III) heteroleptic porphyrin-phthalocyanine double-decker sandwich-like complexes (TPP)M(III)(Pc) (1) are reported (TPP and Pc = dianions of tetraphenylporphyrin and phthalocyanine, respectively; M = La, Pr, Nd, Eu, Gd, Er, Lu, and Y). The electron transfer reactions of these M(III) complexes are presented. They undergo up to four reversible one-electron transfers in nonaqueous media. The spectroscopic properties of these (TPP)M(III)(Pc) (1) sandwich-like derivatives are consistent with the presence of a one-electron-oxidized pi-radical phthalocyanine ring, Pc(.-), as a ligand. Accordingly, these pi-radical complexes 1 yield monoanionic species (TPP)M(III)(Pc)(-) 2 upon reversible one-electron reduction and di-pi-radical complexes (TPP)M(III)(Pc)(+) 3 containing a tetraphenylporphyrin pi-radical and a phthalocyanine pi-radical ligand upon reversible one-electron oxidation. In the neutral complexes 1 and the di-sc-radical derivatives 3, the energies of the near-infrared bands are linearily correlated with the ionic radii r(i) of the tervalent central metals. A decrease of the two reversible one-electron reduction and the first reversible oxidation potentials parallels a decrease of the ionic radii and, hence, the ring-ring separations in these sandwich double-decker species. A protonated lanthanum derivative, (TPP)LaH(Pc) (1[H](La)), has been isolated which shows an IR spectral band at 3280 cm(-1), consistent with an N-H stretching vibration corresponding to a protonated tetrapyrrole ligand. The crystal and molecular structures of the lanthanum derivative (TPP)La(Pc). 2CH(2)Cl(2) (1(La). 2CH(2)Cl(2)) and the singly-oxidized gadolinium species (TPP)Gd(Pc)SbCl6. 2(CH2Cl2),(H2O) (3(Gd)(SbCl6). 2(CH2Cl2),(H2O)) have been established. Crystal data: 1(La). 2CH(2)Cl(2), monoclinic, P2(1)/c, a = 12.935(5) Angstrom, b = 18.674(6) Angstrom, c = 26.114(9) Angstrom, beta = 90.90(2)degrees, Z = 4; 3(Gd)(SbCl6). 2(CH2Cl2),(H2O), triclinic, P (1) over bar, a = 18.190(5) Angstrom, b = 16.100(5) Angstrom, c = 14.130(4) Angstrom, alpha = 104.87(2)degrees, beta = 104.17(2)degrees, gamma = 107.72(2)degrees, Z = 2. These studies confirm the double-decker sandwich-type structures of these derivatives. [References: 48]