ContentsI. Introduction 563 II. Synthesis 564 A. Hemiporphyrazines 564 B. Triazolehemiporphyrazines 569 C. Other Hemiporphyrazines 570 III. Molecular Organization of Hemiporphyrazines in Condensed Phases 571 IV. Hemiporphyrazines as Units for Molecular Organic Materials 573 V. Concluding Remarks 574 VI. Acknowledgments 574 VII. References 574

The specific synthesis of a metal-free bisdienophilic phthalo-ability of 3 to undergo Diels-Alder reactions was tested by cyanine 3, suitable for repetitive Diels-Alder reactions, is re-reaction with an excess of 1,2,3,4-tetraphenylcyclopentadieported. This was achieved by condensation of 1,3,3-trichloro-none (5). Experimental data of the hemiporphyrazines 9, 10, 6/7-nitroisoindolenine (1) and 4,9-dibutoxy-2,3,5,8-tetrahy-and 11, which can be used as precursors for the synthesis of dro-1,3-diimino-1H-5,8-epoxybenz[flisoindoline (2). The ladder polymers, are also given in the Experimental Section.

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The bisdienophilic (hemiporphyrazinato)nickel complexes la-d bearing various alkoxy groups were synthesized from diiminoisoindoles 9a-d, diaminopyridines 10a, d, and nickel acetate. Reaction of la-d with a n excess of pentaene 3 delivered the macrocyclic bisdienes 2a-d. The hemiporphyrazines were characterized by 'H-and 13C-NMR spectroscopy. The NMR spectra of the 1,6,16,21-tetrabutoxy-substituted compounds l b and 2b are discussed with respect to the presence of synlanti isomers.Recently, we reported on the (hemiporphyrazinato)nickel-(11) complexes (HpNi) 1, 2['1 and the pentaene 3['] as building blocks for the synthesis of ladder oligomers and polymers, e.g. the conversion of equimolar amounts of 1 and 2 (with R' = C4H9, R2 = H) in a repetitive Diels-Alder reaction delivered the polymer 4. The compounds 1 and 2 can be classified as macrocyclic bisdienes and bisdienophiles. We now describe the synthesis of the nickel hemiporphyrazines 1 and 2 bearing various peripheral alkoxy groups. The 1,6: 16,21-tetrasubstituted HpNi as 1 are superior to the related 2,5 : 17,2O-tetrasubstituted compounds concerning their reactivity in Diels-Alder reactions"]. This fact may be due to steric reasons.The synthetic route started with tetrabromohydroquinone (5)r4], which was obtained from hydroquinone and bromine in acetic acid. Treatment of the disodium salt of 5 with alkyl halidesL51 [RX = CH31 (a); C4H9Br (b); C6H13Br (c)] led to the corresponding tetrabromohydroquinone bisalkyl ethers 6a-c. Compounds 6a-c were subsequently converted at -50°C with a 1.2 molar amount of nBuLi to the corresponding monoarynes, which in situ underwent with furan a Diels-Alder reaction[q with formation of 5,sdialkoxy-6,7-dibromo-1,4-dihydro-1,4-epoxynaphthalenes 7a-c. A Rosenmund-von Braun of 7a-c using CuCN in DMF afforded 6,7-dicyanonaphthalenes 8a-c. The reaction of 8a-c with NH3 in MeOH (catalyzed by CH30-, 7 days) delivered the corresponding diiminoisoindoles 9a-c. To synthesize the hemiporphyrazines la-d[*], the isoindoles 9a-c were stirred in n-butanol at 100°C with 2,6-diaminopyridine or 2,6-diamino-4-butoxypyridine, respectively. The subsequent addition of Ni(OAc), . 4 HzO at 100°C led to a strong evolution of ammonia. The metalation was finished after an additional heating at 120 "C for 2 hours. The products were purified by column chromatography (alumina and silica gel). The yields of the macrocycles la-d increase with increasing chain length of the peripheral alkoxy substituents.The excellent solubility of the HpNi la-d in solvents like chloroform, dichloromethane, or toluene allows their characterization by 'H-and "C-NMR spectroscopy. Figure 1 shows as an example the 'H-NMR spectrum of lb.Characteristic of the 'H-NMR spectra of hemiporphyrazines are the signals resulting from 9-H (triplet, 6 = 7.37) and 8-H (doublet, 6 = 6.47) of the pyridinc fragment. The resonances of 1-H and 2-H appear as singlets at 6 = 7.00 and 5.90, respectively. The HpNi la-d are present as a mixture of synlanti isomers due to the relative orientation of the oxy...

Macrocyclic bis-dienes and a diendienophile were prepared in Diels-Alder reactions starting from the bis-dienophilic (hemiporphyrazinato)nickel complex 1. 1 was reacted either with the tetraene 2 or with tetraphenylcyclopentadienone (4). By combination of macrocyclic bisdienes and bis-dienophiles, ladder-type oligomers were synthesized. They are precursors to the corresponding conjugated molecules, which are of interest as potential organic conductors. Monofunctional and bifunctional dienophilic macrocycles were also allowed to react with [60]fullerene to give the corresponding mono- and bis-fullerene adducts.