| Abstract
| - 1H NMR investigations of high-spin and low-spin iron(III) complexes of 5,10,15-triphenylporphyrin and its dehydrodimerization product, bis(10,15,20-triphenylporphyrin), were performed to explore the effect of a direct meso−meso linkage on the electronic structure.
- The 1H NMR spectra of iron(III) complexes of dimeric 5,5‘-bis(10,15,20-triphenylporphyrin) [(TrPPH2)2], 5,5‘-bis(10,15,20-tris(p-methoxyphenyl)porphyrin) [(Tr(p-MeOP)PH2)2], and hybrid (TrPPH2)(Tr(p-MeOP)PH2) andthe respective monomeric 5,10,15-triphenylporphyrin (TrPPH2) and 5,10,15-tris(p-methoxyphenyl)porphyrin [Tr(p-MeOP)PH2] have been investigated in order to elucidate an impact of a direct meso−meso linkage on the electronicstructure of corresponding high- and low-spin iron(III) porphyrins. The following species, covering the representativespin/oxidation states, have been investigated: (TrPP)2(FeIIICl)2 (high spin); [(TrPP)2(FeIII(CN)2)2]2- (low spin);[(TrPP)2(FeIIICl)2]+ (high-spin iron(III), diporphyrin radical); [(TrPP•)2(FeIIICl)2]2+ (high-spin iron(III), diradicalof diporphyrin). The iron(III) diporphyrins (TrPP)2(FeIIICl)2, [(TrPP)2(FeIII(CN)2)2]2-, {[(TrPP)FeIII(CN)2][(Tr(p-MeOP)P)FeIII(CN)2]}2-, and [(TrPP)2(FeIIICl)2]2+ revealed the 1H NMR features which have been typicallyencountered in the spectra of the relevant monomeric complexes. Thus magnetic interactions between two subunitsvia skeleton appear to be minor. The characteristic broadening and/or paramagnetic shifts of 3-H and 7-H resonanceswere determined and are diagnostic features of the meso−meso linkage. One-electron, ligand-based oxidation of(TrPP)2(FeIIICl)2 to produce [(TrPP)2(FeIIICl)2]+ was observed with the unpaired electron delocalized over bothmacrocycles. The structure of (Tr(p-MeOP)P)ZnII·0.4CH2Cl2, the fundamental building block in synthesis ofdiporphyrins, was determined by X-ray crystallography. (Tr(p-MeOP)P)ZnII crystallizes in the monoclinic spacegroup C2/c with a = 47.744(9) Å, b = 9.090(2) Å, c = 15.571(2) Å, β = 93.770(13)°, and Z = 8. The refinementof 494 parameters and 4361 reflections yields R1 = 0.0756, wR2 = 0.2169. The (Tr(p-MeOP)P)ZnII presentscharacteristic features of zinc(II) tetraphenylporphyrin. The molecular periphery of (Tr(p-MeOP)P)ZnII has a fullyexposed meso position and two partially exposed pyrrole rings.
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