H-1 NMR investigations of triphenylporphyrin metal complexes and electronic interactions in iron(III) complexes of meso-meso linked 5,5 '-bis(10,15,20-triphenylporphyrin)

The H-1 NMR spectra of iron(II) complexes of dimeric 5,5'-bis(10,15,20-trip henylporphyrin) [(TrPPH2)(2)], 5,5'-bis(10,15,20-tris(p-methoxyphenyl)porph yrin) [(Tr(p-MeOP)PH2)(2)], and hybrid (TrPPH2)(Tr(p-MeOP)PH2) and the resp ective monomeric 5,10,15-triphenylporphyrin (TrPPH2) and 5,10,15-tris(p-met hoxyphenyl)porphyrin [Tr(p-MeOP)PH2] have been investigated in order to elu cidate an impact of a direct meso-meso linkage on the electronic structure of corresponding high- and low-spin iron(III) porphyrins. The following spe cies, covering the representative spin/oxidation states,have been investiga ted: (TrPP)(2)((FeCl)-Cl-III)(2) (high spin); [(TrPP)(2)(Fe-III(CN)(2))(2)] (2-) (low spin); [(TrPP)(2)((FeCl)-Cl-III)(2)](+) (high-spin iron(III), dip orphyrin radical); [(TrPP.)(2)((FeCl)-Cl-III)(2)](2+) (high-spin iron(III), diradical of diporphyrin). The iron(III) diporphyrins (TrPP)(2)((FeCl)-Cl- III)(2), [(TrPP)(2)(Fe-III(CN)(2))(2)](2-), {[(TrPP)Fe-III(CN)(2)][(Tr(p-Me OP)P)Fe-III(CN)(2)]}(2-), and [(TrPP)(2)((FeCl)-Cl-III)(2)](2+) revealed th e H-1 NMR features which have been typically encountered in the spectra of the relevant monomeric complexes. Thus magnetic interactions between two su bunits via skeleton appear to be minor. The characteristic broadening and/o r paramagnetic shifts of 3-H and 7-H resonances were determined and are dia gnostic features of the meso-meso linkage. One-electron, ligand-based oxida tion of (TrPP)(2)((FeCl)-Cl-III)(2) to produce [(TrPP)(2)((FeCl)-Cl-III)(2) ](+) was observed with the unpaired electron delocalized over both macrocyc les. The structure of (Tr(p-MeOP)P)Zn-II. 0.4CH(2)Cl(2), the fundamental bu ilding block in synthesis of diporphyrins, was determined by X-ray crystall ography. (Tr(p-MeOP)P)Zn-II crystallizes in the monoclinic space group C2/c with a = 47.744(9) Angstrom, b = 9.090(2) Angstrom, c = 15.571(2) Angstrom , beta = 93.770(13)degrees, and Z = 8. The refinement of 494 parameters and 4361 reflections yields R-1 = 0.0756, wR(2) = 0.2169. The (Tr(p-MeOP)P)Zn- II presents characteristic features of zinc(II) tetraphenylporphyrin. The m olecular periphery of (Tr(p-MeOP)P)Zn-II has a fully exposed meso position and two partially exposed pyrrole rings.