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

The synthesis and spectroscopic properties of the neutral metal(III) h eteroleptic porphyrin-phthalocyanine double-decker sandwich-like compl exes \(TPP)M(III)(Pc)\ (1) are reported (TPP and Pc = dianions of tetr aphenylporphyrin and phthalocyanine, respectively; M = La, Pr, Nd, Eu, Gd, Er, Lu, and Y). The electron transfer reactions of these M(III) c omplexes are presented. They undergo up to four reversible one-electro n transfers in nonaqueous media. The spectroscopic properties of these \(TPP)M(III)(Pc)\ (1) sandwich-like derivatives are consistent with t he 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-electro n reduction and di-pi-radical complexes \(TPP)M(III)(Pc)\(+) 3 contain ing a tetraphenylporphyrin pi-radical and a phthalocyanine pi-radical ligand upon reversible one-electron oxidation. In the neutral complexe s 1 and the di-sc-radical derivatives 3, the energies of the near-infr ared bands are linearily correlated with the ionic radii r(i) of the t ervalent central metals. A decrease of the two reversible one-electron reduction and the first reversible oxidation potentials parallels a d ecrease of the ionic radii and, hence, the ring-ring separations in th ese sandwich double-decker species. A protonated lanthanum derivative, \(TPP)LaH(Pc)\ (1[H](La)), has been isolated which shows an IR spectr al band at 3280 cm(-1), consistent with an N-H stretching vibration co rresponding to a protonated tetrapyrrole ligand. The crystal and molec ular 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) Angst rom, beta = 90.90(2)degrees, Z = 4; 3(Gd)(SbCl6). 2(CH2Cl2),(H2O), tri clinic, 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)de grees, gamma = 107.72(2)degrees, Z = 2. These studies confirm the doub le-decker sandwich-type structures of these derivatives.