Porphyrazine ligands

In this chapter, the porphyrazines are named in one of two ways. For simple substitution patterns, substituents will be denoted directly for example, Cu(II) oc-taethylporphyrazine can be written Cu[pz(Et)g], When the pattern is more complex, or general concepts are discussed, the porphyrazines are systematically named based on the nature of their substituents, using the general formula, M[pz (AmB4 ), where M represents the metal ion and its axial ligands (or two hydro-... 

Sandwich complexes of porphyrazines are prepared by direct intercalation of lanthanides between two pz ligands, the route commonly utilized for the preparation of porphyrin sandwich complexes. Interestingly, the synthetic method used for the preparation of bis(phthalocyanines), starting from the dinitrile or the dilithium substituted monophthalocyanine, has never been successfully implemented for the synthesis of porphyrazines (77). 

Optical Properties. The double-decker complexes of porphyrazines have characteristic electronic absorption spectra (Table V). The intense Soret bands of the double-decker complexes are blue shifted with respect to the single pz ligand as a consequence of the strong n-n interactions. Another characteristic of sandwich compounds is the additional appearance of absorption bands shifted to the red (termed Q ) and to the blue (termed Q") of the normal g-band region. These new transitions are thought to result from orbitals delocalized over the two macrocyclic ligands (33, 82). 

M[pz(A4)] A = S2ML2. The octakis(.V-R)porphyra/,ines reported by Schramm and Hoffman (2), M[pz(S-R)8 (M = Ni, Cu), (60), can be converted to the octathiolate M[pz(S )g] (Scheme 11) via reductive cleavage of the sulfur-carbon bond when R = benzyl (Bn), and this tetra-bis(dithiolate) can then be peripherally capped with metal-ligand systems to yield peripherally tetrametalated star porphyrazines. The benzyl dinitrile 57 can be macrocyclized around magnesium butoxide to form [Mg[pz(S-Bn)8] (58) (35-40%), which can then be demetalated with trifluoroacetic acid to form 59 (90%), which is subsequently remetalated with nickel or copper acetate to form 60a (95%) and 60b (70%) (Scheme 11) (3, 23, 24). Deprotection of 60a or 60b with sodium in ammonia yields the Ni or Cu tetra-enedithiolates, 61a or 61b to which addition of di-ferf-butyl or n-butyl tin dinitrate produces the peripherally metalated star porphyrazines 62a (37%), 62b (80%), and 62c (41%). 

As Table XVIII shows, the solitaire pzs, 66a and 67b have reductions very close to those reported for H2(pc) and are more negative than those reported for 47. Additionally, for solitaire porphyrazines 67b-67d, which have a [l,T-(diphenylphosphino) ferrocene] palladium(II) peripheral ligand, a reversible one-electron oxidation due to the ferrocene was measured at +0.18 V. 

Electrochemistry-EPR. The redox potentials of the porphyrazines, 69a, 69b, 70a, and 70b were measured using cyclic voltammetry (Table XX). The redox potentials of the molybdocene appended porphyrazines 70a and 70b showed marked changes from that observed for the parent ligands 69a or 69b suggesting that the peripheral metalation by molybdocene profoundly alters the physiochemical properties of the macrocycle by more than just the sum of the two parts (6). 

Subsequent reaction of porphyrazines 170 and 171 with Cu(OAc)2 resulted in the selective metalation within the macrocyclic cavity to provide the corresponding copper complexes 166 (62%) and 172 (47%). Treatment of pz 170 with manganese acetate and iron sulfate in dimethyl sulfate gave the dmso adducts 173 (70%) and 174 (85%), respectively (168). Axial ligation was also observed when other metals were incorporated such as cobalt acetate, nickel acetate, and zinc acetate to give the metal complexes 175 (83%), 176 (70%), and 177 (90%) as the hydrates. The axial ligand of... 

Porphyrazines have also been used to prepare metal-metal bonded dimers with ruthenium and osmium, specifically homometallic dimers comprised of two metallic octaethylporphyrazine and heterometallic dimers comprised of one metallic oc-taethylporhyrazine ligand and one metallic octaethylporphyrin ligand have been reported (189-191). The major bonding interactions that occur in these systems are directly between the two metal centers. 

Keywords Ligand, oktakis, 3-Phenylproply bromide, porphyrazine, spectroscopy, synthesis... 

Following the formation of novel ligand, Mg-porphyrazine will be prepared by using magnesium butanolate. Then treating Mg-Pz with CH COOH is produced... 

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