Octaethylporphyrin, OEP

Porphyrin complexes have been the most intensively studied macrocyclic complexes of these metals [129]. They are formed in a wide range of oxidation states (II-VI) and they are, therefore, treated together under this heading, though most of the chemistry for ruthenium lies in the II-IV states. Octaethylporphyrin (OEP) complexes are typical. 

The octaethylporphyrin (OEP) complex cocrystalline with C60, namely Pdn(OEP)-C6o 1.5C6H6 is one of the first examples of the anti-formed macrocyclic metal complexes of OEPs.180,181... 

In 1988, Ono and Maruyama reported a very simple synthesis of octaethylporphyrin (OEP) from 3,4-diethylpyrrole-2-carboxylate, as shown in Eq. 10.44 49 Reduction of this pyrrole with LiAlH4 gives 2-hydroxyethylpyrrole, which is converted into OEP on treatment with acid and an oxidizing agent. This route is very convenient for synthesis of porphyrins. This method is now used extensively for synthesis of P-substituted porphyrins.50 For example, a highly conjugated porphyrin, shown in Eq. 10.45, has been prepared by this route.51 The requisite pyrroles are prepared from nitro compounds or sulfones thus, various substituents are readily introduced into porphyrins. 

A prime example of this is the crucial ease of such oxidation in the magnesium(II) complex of the chlorin system present in chlorophyll during photosynthesis. Table 8 shows the half-wave potentials for the first ring oxidation of some metalloporphyrins, the examples chosen being based on 5,10,15,20-tetraphenyl porphyrin, TPP (2) and on 1,2,7,8,12,13,17,18-octaethylporphyrin, OEP (16). 

Couples are shown in volts. Measurements were done in CH2C12 with 0.1 MTBAPFg as the electrolyte using a Pt working electrode, Ag/AgCl reference electrode and are reported versus Fc+/Fc. Octaethylporphyrin = oep. 

A range of neutral, singly and doubly oxidized heteroleptic double-decker complexes of the type [M(IV)(P)(Pc)](n), where n = 0, +1, or +2, M=Zr or Hf, P = the dianion of octaethylporphyrin (OEP) or tetraphenylporphyrin (TPP), and Pc = the dianion of phthalocyanine, has been reported. Each oxidized or reduced compound was characterized by UV-visible and/or EPR spectroscopy. The neutral compounds all undergo two reversible ring-centered oxidations and two reversible ring-centered reductions. The redox potentials were found to depend upon the type of macrocycle. They also vary with the size of metal ion in the case of oxidation but not in reduction, where E° values are relatively unaffected and shift by only 20-40 mV upon going from Hf(P)(Pc) to Th(P)(Pc), as compared to a much larger 220-280 mV shift between E° for the first oxidation of the same compounds [27]. 

Titanium(III) octaethylporphyrin (OEP) has been found to react with dioxygen at low temperatures to give a titanium(IV) /i-peroxo species. Characterization was based on a comparison with the reaction product from H202 oxidation of (OEP)TiO. This compound was shown to have a U-peroxo group by a single crystal X-ray study, O—O = 1.445 A, v0 o = 895 cm-1.13... 

Octaethylporphyrin (OEP) affords three osmium nitrosyl complexes Os(NO)(OMe)(OEP), made from Os(CO)py(OEP), methanol and NO 232 with HF this yields Os(NO)F(OEP)232 and with HC104 it gives 0s(N0)(0C103)(0EP).2SS The nitrosyl carbonyl complex [Os(NO)(CO)Cl2(PPh3)2]BF4 is made by reaction of Os(NO)(CO)Cl(PPh3)2 with HBF4.223... 

There is now a very elegant method to prepare certain MoW4+ compounds, Eq. 18-C-ll, discovered by Luck and Morris,110 and since heavily utilized,111 with some modifications. In the case of octaethylporphyrin (OEP) compounds, it is even possible to make heteronuclear species that combine Mo with metal atoms in other groups, e.g., (OEP)MoRu(OEP) and (OEP)MoOs(OEP).112... 

Relatively few complexes of N-donor ligands are known. One of the best characterized is with the tridentate ligand terpyridyl, which reacts with scandium nitrate to form Sc(terpy )(N03 )s here scandium is connected to 9 atoms, but one Sc-O bond is considerably longer than the others, so a coordination number of 8.5 has been assigned. A range of porphyrin and phthalocyanine complexes exist syntheses often involve the high-temperature routes typical of the transition metals but recently a high-yield low-temperature route has been utilized to make octaethylporphyrin (OEP) complexes ... 

In the context of the preparation of novel arsenic hypervalent species and the systematic stndy of mffling in porphyrins by the influence of axially coordinated ligands to a central element, complexes with arsenic and porphyrins were isolated and fully characterized. The porphyrins used are octaethylporphyrin, (OEP) and tetraphenylporphirin (TPP). Reaction of OEPH2 or TPPH2 with ASCI3 in the presence of lutidine give [(OEP)AsCl] (53) or [(TPP)AsCl] (54) according to equation (35). ... 

Whereas a large number of model heme complexes are derived from the tetraphenylporphyrin moiety, another very important class of porphyrins bearing substituents only at the -pyrrole carbon atoms, has been extensively investigated as models of heme proteins. One of the models most studied is octaethylporphyrin (OEP), which was originally synthesized fi om 2-dimethylaminomethyl-3,4-diethylpyrrole in an acid-catalyzed medium. b378 similar approach is described by Ono et in which OEP, copropor-... 

Large metal ions such as thorium or uranium were also employed in order to combine a porphyrin, octaethylporphyrin (OEP), with a phthalocyanine (Pc) chromophore in face-to-face or double-decker orientation. and Th compounds could be electrogenerated in up to seven different oxidation states. The first two reductions occurred mainly on the Pc ring while the first two oxidations of the same heteroleptic compounds involved primarily orbitals of the porphyrin macrocycle. In contrast, the homoleptic (MP)2 and (MPc)2 derivatives undergo initial one-electron oxidations and reductions which are localized not at a single ring, but involve both macrocycles. ... 

Porphyrins, hydroporphyrins, azaporphyrins, phthalocyanines, corroles, corrins, and related macrocycles were discussed in CCC (1987).144 The octaethylporphyrin complexes of scandium were also previously mentioned in CCC (1987).1 The octaethylporphyrin (oep) scandium chloride complex (oep)ScCl, prepared by the reaction of the dilithium porphyrin with ScCl3(thf)3, has proved... 

Related Zr carborane complexes ZrfeorX -l -CyigHn) (por = TPP, octaethylporphyrin (OEP)) that incorporate porphyrin ligands were readily synthesized from reaction of the... 

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