Magnesium-macrocycle complex

Synthesis. These macrocycles are prepared from seven-membered ring dinitrile complexes, 84a-84c (Scheme 17), which contain either methylene, sulfur or oxygen in the five position (129). These cyclic dinitriles are synthesized by alkylating maleonitrile dithiolate or derivatives thereof with the corresponding dihalide. The dinitriles 84a-84c can be cyclized in magnesium propoxide to form porphyrazines 85a (33%), 85b (19%), and 85c (27%) (Scheme 17), which can be demetalated with trifluoroacetic to form 86a-86c. Additionally, 86a has been remetalated with nickel (87a, 92%), copper (88a, 95%), and zinc (89a, 94%). The sulfur and oxygen derivatives 85b, 85c, 86b, and 86c are of low solubility and are not suitable for further manipulation. 

Analogously, complex 218 was prepared by mixed macrocyclization of 2,5-diiminopyrrolidine (213) with ferf-butylphenylpyrroline (68) in 19% yield. The free base (219) (95%) was obtained by demetalation of magnesium complex 218 with trifluoroacetic acid and subsequent remetalation of 219 with Ni(OAc)2 gave the corresponding nickel complex 220 in 98% yield. 

The phthalocyanine [1-4] system is structurally derived from the aza-[18]-annulene series, a macrocyclic hetero system comprising 18 conjugated n-electrons. Two well known derivatives of this parent structure, which is commonly referred to as porphine, are the iron(III)complex of hemoglobin and the magnesium complex of chlorophyll. Both satisfy the Htickel and Sondheimer (4n + 2)- electron rule and thus form planar aromatic systems. 

Complex 2 decomposes rapidly in air, is only slightly soluble in thf, and is insoluble in many other inert organic solvents. The proton NMR spectrum (thf-d8)5 consists of a singlet at 5 = 1.29 ppm (rel. to SiMe4)(4H, C2H2) and multiplets at 5 = 6.48 and 3 = 6.08 ppm (center of each AA BB multiplet, 4H, CH). The X-ray structure of the magnesium-chloride-free macrocycle 2 has been determined.5... 

The reaction of 2,6-diacetylpyridine with hydrazine in the presence of iron(II) salts yields a macrocyclic azine complex (equation 34).192 Similar complexes of cobalt(II), zinc(II), magnesium ) and scandium(III) have been prepared more recently.193... 

The macrocycle tetrakis(selenadiazole)porphyrazine and its Mg(n) and Cu(n) complexes were prepared <1999MI371>. Reaction of the 3,4-dicyano-l, 2,5-sclcnodiazole 81 with magnesium propylate in propanol gave Mg(ll) complex with water and acetic acid 203 (Scheme 29). The Mg(ll) complex 203 was transformed to compounds 232 and 233 as shown. 

An iron(II) complex of a completely conjugated fourteen-membered hexa-aza ligand has been prepared by the condensation of 2,6-diacetylpyridine with hydrazine in acetonitrile. TTiere are two possible isomers, 134 and 135. X-ray data show that the structure of this complex is best represented by 134 in which the macrocycle is completely planar and the coordination geometry is pentagonal bipyramidal. The iron(II) complex of 134 is extremely labile to nucleophiles 113). The cobalt(II) 113), magnesium(II)114), zinc(II)114), and scandium(III) U5> complexes of this hexa-aza quadradentate ligand have also been prepared. 

In 1978, Vogtle reported the synthesis of a different series of lactam-type macrocycles, which were achieved by the reaction of 2,6-6is(aminomethyl)pyridine with various polyether-fe-acid chlorides138>. Among the coronands reportal were 172 and 173 to date, only the magnesium complex of 173 has been prepared. 

Macrocycles history, 21 metal complexes protonation, 423 Macrocyclic ligands isomerism, 204 Magnesium gravimetry, 528... 

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