Synthesis of Tris (2, 5-dialkynylthieno) cyclotriynes, Tris (4, 5

With the attachment of long side chains, tris(4,5-dialkoxyphenyl)cyclotriynes and tris(2,5-dialkynylthieno)cyclotriynes are structurally similar to he...
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Chem. Mater. 1999, 11, 3050-3057

Synthesis of Tris(2,5-dialkynylthieno)cyclotriynes, Tris(4,5-dialkoxyphenyl)cyclotriynes, and Tetrakis(4,5-dialkoxyphenyl)cyclotetraynes with Long-Chain Alkyl Substituents, and the Nickel and Cobalt Complexes of Tris[4,5-(didodecyloxy)phenyl]cyclotriyne Daming Zhang, Claire A. Tessier,* and Wiley J. Youngs* Department of Chemistry, The University of Akron, Akron, Ohio 44325-3601 Received January 25, 1999. Revised Manuscript Received August 9, 1999

This report focuses on the synthesis of materials designed to be discotic mesogens based on a cyclotriyne core with alkyl side chain substituents. With the attachment of long side chains, tris(4,5-dialkoxyphenyl)cyclotriynes and tris(2,5-dialkynylthieno)cyclotriynes are structurally similar to hexasubstituted triphenylene discotic mesophases. The syntheses of four tris(2,5-dialkynylthieno)cyclotriynes, two tris(4,5-dialkoxyphenyl)cyclotriynes, and two tetrakis(4,5-dialkoxyphenyl)cyclotetraynes are described. The interaction of one of the tris(4,5-dialkoxyphenyl)cyclotriynes with Ni(0) and Co2(CO)8 to form a mononuclear Ni(0) complex and a tetranuclear cobalt cluster are reported. Evidence is also presented to explain why the systems reported herein are not liquid crystals and suggestions for correcting this are made.

Introduction The first examples of discotic liquid crystals were reported in the late 1970s.1 A variety of discotic mesogens and discotic metallomesogens have been reported as summarized in a review article by Chandrasekhar.2 Examples of discotic mesogens include derivatives of benzene,1a triphenylene,3 phthalocyanines,4 1,3,5-triazines,5 and self-assembled trimeric supramolecular disks of 2,3-dihydrophthalazine-1,4-diones.6 Discotic mesogens typically consist of planar or nearly planar central cores surrounded by flexible side chains. Many discotic mesogens form columnar phases, but smectic, lamellar, and cholesteric phases are also known. Discotic liquid crystals and, especially, discotic metalcontaining liquid crystals have attracted a great deal of attention because of their unusual photoelectric, electric, and magnetic properties.2,7 The presence of metals in mesogens opens many exciting possibilities for the preparation of new electronic and magnetic materials. (1) (a) Chandrasekhar, S.; Sadashiva, B. K.; Suresh, K. A. Pramana 1977, 7, 471. (b) Billard, J.; Dubois, J. C.; Tinh, N. H.; Zann, A. Nouv. J. Chim. 1978, 2, 535. (c) Destrade, C.; Mondon, M. C.; Malthete, J. J. Phys., Paris 1979, 40, C3. (2) Chandrashekhar, S. Liq. Cryst. 1993, 14, 3. (3) (a) Tinh, N. H.; Gasparoux, H.; Destrade, C. Mol. Cryst. Liq. Cryst. 1981, 68, 101. (b) Rego, J. A.; Kumar, S.; Dmochowski, I. J.; Ringsdorf, H. Chem. Commun. 1996, 1031. (4) (a) Van Der Pol, J. F.; Neeleman, E.; Zwikker, J. W.; Nolte, R. J. M.; Drenth, W.; Aerts, J.; Visser, R.; Picken, S. J. Liq. Cryst. 1989, 6, 577. (b) Cho, I.; Lim, Y. Mol. Cryst. Liq. Cryst. 1988, 154, 9. (c) Knawby, D. M.; Swager, T. M. Chem. Mater. 1997, 9, 535. (5) Goldmann, D.; Janietz, D.; Festag, R.; Schmidt, C.; Wendorff, J. H. Liq. Cryst. 1996, 21, 619. (6) Sua´rez, M.; Lehn, J.-M.; Zimmerman, S. C.; Skoulios, A.; Heinrich, B. J. Am. Chem. Soc. 1998, 120, 9526.

This report focuses on the synthesis of materials designed to be discotic mesogens based on a cyclotriyne (cyclic trialkyne8) core with alkyl side chain substituents. Due to their extensively conjugated antiaromatic planar structure8k and cavity that is large enough to fit some low oxidation state first-row transition metals, TBC (tribenzocyclyne),8 TTC (trithienocyclotriyne), and other cyclotriynes might be useful as discotic cores for metallomesogens. Cyclotriynes are versatile ligands and the interaction of cyclotriynes with metal moieties has led to the synthesis of a wide variety of novel complexes.9 As part of a rational approach to finding new discotic liquid crystalline materials and to provide new ligands for metal complexes, derivatives of cyclotriynes substituted with long-chain alkoxy groups on the thio(7) (a) Giroud-Godquin, A.-M.; Maitlis, P. M. Angew. Chem., Int. Ed. Engl. 1991, 30, 375. (b) Adam, D.; Closs, F.; Frey, T.; Funhoff, D.; Haarer, D.; Ringsdorf, H.; Schuhmacher, P.; Siemensmeyer, K. Phys. Rev. Lett. 1993, 70, 457. (c) Simon, J.; Sirlin, C. Pure Appl. Chem. 1989, 61, 1625. (d) Adam, D.; Schuhmaclen, P.; Simmerer, J.; Ha¨ussling, L.; Siemensmeyer, K.; Etzbach, K. H.; Ringsdorf, H.; Haarer, D. Nature 1994, 371, 141. (8) (a) Nakagawa, M. In The Chemistry of the Carbon-Carbon Triple Bond-part 2; Patai, S., Ed.; Wiley: New York, 1978; pp 635712 and references therein. (b) Sondheimer, F. Acc. Chem. Res. 1972, 5, 81. (c) Campbell, I. D.; Eglinton, G.; Henderson, W.; Raphael, R. A. J. Chem. Soc., Chem. Commun. 1966, 87. (d) Meier, H. Synthesis 1972, 235. (e) Staab, H. A.; Graf, F. Tetrahedron Lett. 1966, 7, 751. (f) Staab, H. A.; Graf, F. Chem. Ber. 1970, 103, 1107. (g) Staab, H. A.; Bader, R. Chem. Ber. 1970, 103, 1157. (h) Untch, K. G.; Wysocki, D. C. J. Am. Chem. Soc. 1966, 88, 2608. (i) Staab, H. A.; Mack, H.; Wehinger, E. Tetrahedron Lett. 1968, 12, 1465. (j) Barkovitch, A. J.; Vollhardt, K. P. C. J. Am. Chem. Soc. 1976, 98, 2667. (k) Irngartinger, H.; Leiserowitz, L.; Schmidt, G. M. Chem. Ber. 1970, 103, 1119. (l) Huynh, C.; Linstrumelle, G. Tetrahedron 1988, 44, 6337. (m) Solooki, D.; Kennedy, V. O.; Tessier, C. A.; Youngs, W. J. Synlett 1990, 427. (n) Kinder, J. D.; Tessier, C. A.; Youngs, W. J. Synlett 1993, 149. (o) Solooki, D.; Ferrara, J. D.; Malaba, D.; Bradshaw, J. D.; Tessier, C. A.; Youngs, W. J. Inorg. Synth. 1997, 31, 122.

10.1021/cm990046v CCC: $18.00 © 1999 American Chemical Society Published on Web 10/28/1999

Synthesis and Complexation of Cyclotriynes

phene or benzo rings have been synthesized. With the attachment of the long side chains, tris(4,5-dialkoxyphenyl)cyclotriynes and tris(2,5-dialkynylthieno)cyclotriynes are structurally similar to hexasubstituted triphenylenes,10 the traditional discotic liquid crystalline materials. The attachment of long alkoxy side chains to the thiophene or benzo rings of a cyclotriyne should affect the reactivity of the derived metallocyclynes and improve the solubility with respect to the unsubstituted cyclotriyne. In comparison with substituted triphenylenes, cyclotriyne derivatives provide a metal chelating site in the center of the molecule and thereby create the possibility for the preparation of metallomesogens. With the incorporation of a zerovalent metal, such mesogens may provide properties different from the reported metal-containing liquid crystals.

Here we report the synthesis of tris(2,5-dialkynylthieno)cyclotriynes, tris(4,5-dialkoxyphenyl)cyclotriynes, and tetrakis(4,5-dialkoxyphenyl)cyclotetraynes and the interaction of one of the tris(4,5-dialkoxyphenyl)cyclotriynes with Ni(0) and Co2(CO)8 to form a mononuclear Ni(0) complex and a tetranuclear cobalt cluster. Evidence is also presented to explain why the systems reported herein are not liquid crystals and suggestions for correcting this are made. Results and Discussion The combination of tetraiodothiophene11 with the terminal alkynes, 1-octyne, 1-tetradecyne, 2-methyl3-butyn-2-ol, and (trimethylsilyl)acetylene, in the presence of bis(benzonitrile)palladium(II)dichloride, copper(9) (a) Ferrara, J. D.; Tessier-Youngs, C. A.; Youngs, W. J. J. Am. Chem. Soc. 1985, 107, 6719. (b) Ferrara, J. D.; Tessier-Youngs, C.; Youngs, W. J. Organometallics 1987, 6, 676. (c) Ferrara, J. D.; Djebli, A.; Tessier-Youngs, C. A.; Youngs, W. J. J. Am. Chem. Soc. 1988, 110, 647. (d) Ferrara, J. D.; Tessier-Youngs, C.; Youngs, W. J. J. Am. Chem. Soc. 1988, 110, 3326. (e) Ferrara, J. D.; Tessier-Youngs, C.; Youngs, W. J. Inorg. Chem. 1988, 27, 2201. (f) Djebli, A.; Ferrara, J. D.; TessierYoungs, C.; Youngs, W. J. J. Chem. Soc., Chem. Commun. 1988, 548. (g) Ferrara, J. D.; Tanaka, C.; Fierro, C.; Tessier-Youngs, C. A.; Youngs, W. J. Organometallics 1989, 8, 2089. (h) Youngs, W. J.; Kinder, J. D.; Bradshaw, J. D.; Tessier, C. A. Organometallics 1993, 12, 2406. (i) Dunbar, R. C.; Uechi, G. T.; Solooki, D.; Tessier, C. A.; Youngs, W. J.; Asamoto, B. J. Am. Chem. Soc. 1993, 115, 12477. (10) (a) Dubois, J. C. Annl. Phys. 1978, 3, 131. (b) Destrade, C.; Mondon, M. C.; Malthete, J. J. Phys. Paris 1979, 40, C3. (c) Destrade, C.; Mondon, M. C.; Tinh, N. H. Mol. Cryst. Liq. Cryst. Lett. 1979, 49, 169. (11) Gronowitz, S.; Vilks, V. Ark. Kemi 1963, 21, 191.

Chem. Mater., Vol. 11, No. 11, 1999 3051 Scheme 1

(I) iodide, and triphenylphosphine in diisopropylamine gave the 2,5-dialkynyl-3,4-diiodothiophenes 2a-d, respectively (Scheme 1)12 Compounds 2a and 2b are light yellow oils which turn darker gradually on standing. Compounds 2c and 2d are white solids. The combination of 2a or 2b with trimethylsilylacetylene in the presence of the same Pd-Cu catalyst produced the 2,5diakynyl-3-[(trimethylsilyl)ethynyl]-4-iodothiophenes 3a or 3b. Both 3a and 3b are sticky oils and their colors changed from yellow to brown on standing. Most of the thiophene-alkyne conjugated compounds reported here are somewhat light sensitive. Deprotection of 3a or 3b with KF in a mixture of THF and methanol resulted in the formation of the 2,5-dialkynyl-3-ethynyl-4-iodothiophenes 4a or 4b. Compounds 4a and 4b are yellowbrown colored and are more light sensitive than their 2 or 3 analogues, presumably because of the terminal alkyne. (Note: All of the deprotected ethynyl thiophenes mentioned in this paper should be treated as potentially explosive materials.)12 Compound 4c was synthesized in a fashion similar to 4a or 4b except that intermediate 3c was not isolated and purified. The cross-coupling of organotin reagents with organic electrophiles, catalyzed by palladium, provides an efficient method for forming a carbon-carbon bond.13 The reaction of 2d with ethynyltributyltin in THF catalyzed by bis(triphenylphosphine)palladium(II) chloride provided 4d in one step. Cyclization of 4a-d in the presence of Pd-Cu catalyst (12) Neenan, T. X.; Whitesides, G. M. J. Org. Chem. 1988, 53, 2489. (13) (a) Boldi, A. M.; Anthony, J.; Knobler, C. B.; Diederich, F. Angew. Chem., Int. Ed. Engl. 1992, 31, 1240. (b) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508.

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Chem. Mater., Vol. 11, No. 11, 1999 Scheme 2

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CuCl in pyridine to form the cuprous acetylide in situ. Refluxing the cuprous acetylides in pyridine followed by chromatography gave tris(4,5-dialkoxyphenyl)cyclotriynes (9a, 17%; and 9b, 16%), and the nonplanar tetrakis(4,5-dialkoxyphenyl)cyclotetraynes (10a, 12%; and 10b, 16%). The combination of tris[3,4-bis(decyloxy)phenyl]cyclotriyne 9a and Ni(COD)2 in benzene gave the Ni(0) complex 11 (eq 1). The ligand 9a has absorptions at 6.72

(1)

in diisopropylamine led to the formation of tris(2,5dialkynylthieno)cyclotriynes 5a-d in 25%, 13%, 1%, and 5% yields, respectively. These cyclotriynes are white solids, but turned yellow and eventually brown on standing in the air, especially when subjected to light. Compounds 5c and 5d decomposed gradually upon heating. The synthesis of tris(4,5-dialkoxyphenyl)cyclotriyne and tetrakis(4,5-dialkoxyphenyl)cyclotetraynes is shown in Scheme 2. The combination of catechol with 1-bromododecane or 1-bromotetradecanane in DMSO catalyzed by K2CO3 provided 1,2-bis(dialkoxy)benzene 6a or 6b.14 The iodination of 6a or 6b with iodine, catalyzed by mercuric acetate in CH2Cl2, gave 4,5-bis(dialkoxy)1,2-diiodobenzene 7a or 7b.15 Pure 7a was obtained by chromatography on silica gel with hexane/CH2Cl2 as eluant and 7b was obtained by crystallization from EtOH. The palladium-catalyzed coupling of 7a or 7b with trimethysilylacetylene in the presence of Pd(PhCN)2Cl2, CuI, and Ph3P in diisopropylamine at 70 °C gave 4,5-bis(alkoxyphenyl)-1-iodo-2-[(trimethylsilyl)ethynyl]benzene. Because the electron-donating properties of dialkoxy groups lower the reactivity of dialkoxybenzene toward the nucleophile, relatively higher temperatures and longer reaction times were needed to give good yields. Without purification, the products were deprotected with KF in THF/methanol to give 8a and 8b, respectively. The cyclization of 8a or 8b was carried out by a modified Stephens-Castro coupling reaction.16 The terminal alkyne reacted with t-BuOK and then (14) Van der Pol, J. F.; Neeleman, E.; Zwikker, J. W.; Nolte, R. J. M.; Drenth, W. Rec. Trav. Chim. Pays-Bas 1988, 107, 615. (15) Zhou, Q.; Carroll, P. J.; Swager, T. M. J. Org. Chem. 1994, 59, 1294. (16) Kinder, J. D. Ph.D. Dissertation, Case Western Reserve University, 1992.

ppm for the aromatic protons, 119.90 ppm for the ipsobenzo carbons and 92.05 ppm for the alkyne carbons in the 1H and 13C NMR spectra, respectively. These absorptions were shifted to 7.36, 136.32, and 108.54 ppm upon complexation of Ni, respectively. These shifts are consistent with those observed when TBC forms a complex with Ni(0).9a,g Compound 11 gives IR absorptions at 1953 cm-1 for the Ni(0)-complexed triple bonds. The molecular ion peak was observed in the FD-MS spectra. The combination of tris(3,4-didecanoxyphenyl)cyclotriyne 9a with dicobaltoctacarbonyl in diethyl ether gave the tetracobalt cluster 12 (eq 2). Characterization of this

(2)

unusual 66-electron cluster is based on elemental analysis and the comparison of the infrared spectra of 12 with that of (Co)4(CO)9TBC.9 The (Co)4(CO)9TBC complex has been previously characterized by X-ray crystallography. The triple-bond IR absorption (1864 cm-1) is the same as that of (Co)4(CO)9TBC (1865 cm-1).17 Due to the presence of a paramagnetic substance, the NMR spectra are not helpful to the characterization. The FD-MS spectra only gave an ion peak of a tricobalt complex (C93H132O15Co3). We assume that the fourth cobalt was lost in the process of measurement. The cyclotriynes and metallocylcotriynes reported in this paper all have sharp melting points and further examination of these materials by optical and X-ray techniques indicated that, in the pure form, these compounds do not possess liquid crystal properties. For the rational design of liquid crystals based on cyclotri(17) Djebli, A. Ph.D. Dissertation, Case Western Reserve University, 1991.

Synthesis and Complexation of Cyclotriynes

Chem. Mater., Vol. 11, No. 11, 1999 3053

Figure 1. Packing down c axis.

ynes, it is necessary to understand why the systems reported here do not have liquid crystal properties. It is well-known that the thermotropic liquid crystalline state is very delicate. Very different phase behaviors and the appearance or disappearance of mesophases can result from slight changes in structure.18 Many factors can influence the properties of a potential mesogen. These factors include dipole-dipole interactions, dispersion forces and molecular shape.19 Molecular shape is especially important for discotic liquid crystals. The magnitude of dipolar interactions and dispersion forces is also crucial. The mesogenic properties could be lost when they are either too strong or too weak. A comparison of the structures of 5a, 5b, 9a, 9b, and 11 to the structures of known liquid crystals was considered. Most discotic mesophases are formed from molecules which have relatively planar aromatic core with four, six, or eight side chains.18b The tris(4,5dialkoxyphenyl)cyclotriynes with long-chain alkyl and alkoxy substituents reported here meet this first requirement. However few publications report the ratio of the diameter of the rigid core to that of the whole molecule. We have considered this aspect and have found that this ratio varies from 1:2 to 1:4 in the systems reported herein, within the range of ratios 1:2 to 1:4 for known benzene,20 triphenylene,21,22 and phthalocyanine23 liquid crystals. Other structural as(18) (a) Collings, P. Liquid Crystals- Nature’s Delicate Phase of Matter; Princeton University Press: Princeton, 1990. (b) Thermotropic Liquid Crystals; Gray, G. W., Ed.; John Wiley: New York, 1987. (19) Demus, D. Liq. Cryst. 1989, 5, 75. (20) Frank, F. C.; Chandrasekhar, S. J. Phys. 1980, 41, 1285. (21) Safinya, C. R.; Liang, K. S.; Varady, W. A. Phy. Rev. Lett. 1984, 53, 1172. (22) Gramsbergen, E. F.; Hoving, H. J.; de Jeu, W. H.; Praefcke, K.; Kohne, B. Liq. Cryst. 1986, 1, 397. (23) Guillon, D.; Skoulios, A.; Piechocki, C.; Simon, J.; Weber, P. Mol. Cryst. Liq. Cryst. 1986, 100, 275.

pects in which 5a, 5b, 9a, 9b, and 11 differ from known discotic liquid crystals are more difficult to quantify. m-Phenylacetylene hexamers, termed phenylacetylene macrocycles, have been reported to have liquid crystal properties at greater than 100 °C.24 The liquid crystalline properties of the phenylacetylene macrocycles are reported to be very dependent on the types of substituents on the rings with very minor changes in the substituents making the difference between having and not having liquid crystal properties. The crystal structure of 5a in the solid state was determined by X-ray crystallography.25 This crystal structure has a large R value (20%) due to disorder. Because of the thermal motion and random orientation of the alkyl chains, only the location of the atoms within the cyclyne core (including the thienyl ring atoms and the pendant alkynes) and a few short alkyl fragments were found. Therefore the crystal structure is of limited use to determine intramolecular distances and angles. However, this structure can provide information on the packing of 5a, Figure 1. Even with the high R value this information is of higher accuracy than that obtained from powder pattern studies. The packing of 5a may be the key to understanding why this molecule and, by extrapolation, the other cyclotriynes discussed in this paper, do not exhibit discotic mesophase properties. The unit cell contains two molecules which lie on the mirror planes and are related by an inversion center. Each molecule is centered about a 3-fold axis so that the (24) (a) Zhang, J.; Moore, J. S. J. Am. Chem. Soc. 1994, 116, 2655. (b) Mindyuk, O. Y.; Stetzer, M. R.; Heiney, P. A.; Nelson, J. C.; Moore, J. S. Adv. Mater. 1998, 10, 1363. (25) X-ray crystal data for tris(2,5-dioctynylthieno)cyclotriyne (5a): hexagonal space group P63/m, a ) 22.478(3) Å, c ) 7.340(1) Å, V ) 3212.2(7) Å3, Z ) 2, T ) 130 K, 1655 unique reflections and 710 observed (F >4.0σ(F)), R ) 0.29, wR(F) ) 0.20. Although the structure could not be solved completely, it is adequate to determine the packing.

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Figure 2. Packing down a axis.

asymmetric unit is defined as 1/3 of the entire molecule. When the packing is viewed down the unique axis (c), see Figure 1, the cyclotriyne portion of the molecules stack one on top of another with an intercyclotriyne spacing distance of 7.340(1) Å. This very large intercyclotriyne spacing distance is filled with the disordered alkyl chains from an adjacent stack of cyclotriynes as shown when the packing diagram is viewed looking down the a axis, see Figure 2. Figures 1 and 2 show that in compound 5a the cyclotriyne core does not interact with another cyclotriyne core but instead is “solvated” by the disordered alkyl chain of molecules from an adjacent column. Comparison with the triphenylene liquid crystals indicates that there is a stronger interaction between an alkyne and an alkyl chain than there is between an aromatic ring and an alkyl chain. In general, discotic liquid crystals form because the planar or nearly planar portion of the molecules, such as the triphenylene core of the triphenylene liquid crystals, interact most strongly with each other and not with the side chain. This results in molecules stacking in a columnar or slipped stacked fashion with a close discotic core to discotic core interaction. To promote the stacking of the cyclotriyne cores it will be necessary to decrease the strength of the interaction between the cyclotriyne core and the side chain. One possible way of doing this is to make the side chain less miscible with the cyclotriyne core by incorporating polar functionality, such as carboxylic acids, in the side chains. Fluorocarbons are highly immiscible with aliphatic hydrocarbons and have been found useful in promoting liquid crystalline properties.26 We are currently synthesizing analogues to 5, 9, and 10 with either polar groups or fluorocarbons present in the side chains. Experimental Section All reactions were performed using standard inert atmosphere techniques unless otherwise specified. All organic workups were conducted in air. Melting points were determined on a Thomas-Hoover melting point apparatus and are uncorrected. 1H NMR spectra were recorded at 300 MHz and 13C NMR spectra were recorded at 75 MHz. FD-MS data were provided by Dr. Robert Lattimer of BFGoodrich Company. Elemental analyses were obtained by Midwest Microlab, Indianapolis, IN. Optical and X-ray powder studies were done a the Kent State Liquid Crystal Institute. (Trimethylsilyl)acetylene (TMSA), octyne, tetradecyne, and 2-methyl-3-butyn-2-ol were obtained from Farchan Laboratories and were used after purification by fractional distillation. Copper(I) iodide, thiophene, palladium dichloride, bis(triphenylphosphine)palladium dichloride, ethynyltributyltin, iodic acid, iodine, 1-bromodecane, and 1-bromotetradecan were obtained from Aldrich and were used without further purifica(26) Arehart, S. V.; Pugh, C. J. Am. Chem. Soc. 1997, 119, 3027.

tion. Diisopropylamine (ACROS) and pyridine (Aldrich) were distilled from KOH before use. Tetrahydrofuran (THF) was distilled from purple sodium benzophenone solutions before use. Bis(benzonitrile)palladium dichloride27 and bis(dibenzylideneacetone)palladium(0)28 were prepared according to literature procedures. Synthesis of Tetraiodothiophene (1). In air, thiophene (16.8 g, 0.2 mol), I2 (89.4 g, 0.352 mol), and iodic acid (31 g, 0.716 mol) were added to a solution of acetic acid (170 mL) air, water (78 mL), carbon tetrachloride (64 mL), and sulfuric acid (4.5 mL). The mixture was refluxed for one week. CCl4 (100 mL) and H2O (50 mL) were added, and the mixture was heated to reflux. After the mixture was cooled to room temperature, the solid was filtered out and washed with H2O, 5% Na2S2O3 solution, and H2O successively and dried in air. Recrystallization twice from dioxane resulted in a yellow solid 1 (88.4 g, 75.2%), mp 201-202 °C.11 Synthesis of 2,5-Dialkynyl-3,4-diiodothiophenes (2). To a 1000-mL flask were added tetraiodothiophene (10.2 g 17.4 mmol), bis(benzonitrile)palladium dichloride (0.324 g, 0.84 mmol), triphenylphosphine (0.444 g, 1.68 mmol), CuI (0.168 g, 0.84 mmol), and freshly distilled diisopropylamine (500 mL). The mixture was cooled to 0 °C. Degassed alkyne (35.68 mmol) was added via syringe. The mixture was stirred at 0 °C for 1 h and at room temperature for 20 h and refluxed for 1 h. After cooling to room temperature, the mixture was filtered. The solid was washed with CH2Cl2 (3 × 25 mL), and the washings were combined. The solvent was removed in vacuo, and the residue was dissolved in methylene chloride, washed consecutively with dilute HCl and water, and dried over MgSO 4. After filtration, the solvent was removed. The residue was chromatographed on silica gel. 2,5-Dioctynyl-3,4-diiodothiophene (2a). Hexane was used as the eluant. A yellow-brown oil (8.24 g, 85.8%) was obtained: IR (neat) 2903, 2224, 1455, 1376, 1323, 1276, 830, 730 cm-1;1H NMR (CDCl3) δ 2.46 (t, 4 H), 1.59 (m, 4 H), 1.46 (m, 4 H), 1.30 (m, 8 H), 0.89 (t, 6 H); 13C NMR (CDCl3) δ 126.41, 99.47, 98.70, 75.19, 31.27, 28.51, 28.23, 22.54, 19.83, 14.07. Anal. Calcd for C20H26SI2 (552.27): C, 43.49; H, 4.75. Found C, 43.69; H, 4.82. 2,5-Ditetradecynyl-3,4-diiodothiophene (2b). Petroleum ether was used as the eluant. A yellow-brown oil (10.45 g, 85.3%) was obtained: 1H NMR (CDCl3) δ 2.49 (t, 4 H), 1.63 (m, 4 H), 1.48 (m, 4 H), 1.27 (s, br, 32 H), 0.89 (t, 6 H); 13C NMR (CDCl3) δ 126.70, 99.75, 98.92, 75.45, 32.16, 29.89, 29.76, 29.59, 29.32, 29.08, 28.52, 22.93, 20.07, 14.36. Anal. Calcd for C32H50SI2 (720.58): C, 53.33; H, 6.99. Found: C, 53.49; H, 6.97. 2,5-Di(2-hydroxy-2-methyl-3-butynyl)-3,4-diiodothiophene (2c). A mixture of methylene chloride and acetone (30: 1) was used as the eluant. A white solid (7.0 g, 82%) was obtained: mp 140-141 °C; IR (neat) 3563, 3239, 2980,2931, 2520, 2289, 2211, 1710, 1450, 1386, 1245, 1154, 959, 896 cm-1; 1H NMR (CDCl ) δ 1.65 (s, 12H), 2.08 (s, 2H); 13C NMR (CDCl ) 3 3 δ 126.15, 102.36, 100.87, 76.95, 66.07, 31.35. Anal. Calcd for C14H14I2O2S (500.11): C, 33.62; H, 2.82. Found: C, 33.85; H, 2.83. 2,5-Di[(trimethylsilyl)ethynyl]-3,4-diiodothiophene (2d). Hexane was used as eluant. A white solid (7.0 g, 78%) was obtained: mp 151-152 °C; 1H NMR (CDCl3) δ 0.286 (s, 18H). (27) Anderson, G. K.; Lin, M. Inorg. Synth. 1990, 28, 60. (28) Louise, E. C.; John, L. S. Inorg. Synth. 1990, 28, 126.

Synthesis and Complexation of Cyclotriynes 13C

NMR (CDCl3) δ 126.69, 104.91, 101.32, 98.09, 0.13. Anal. Calcd for C14H18I2SSi2 (528.32): C, 31.82; H, 3.43. Found: C, 32.38; H, 3.57. Synthesis of 2,5-Dialkynyl-3-[(trimethylsilyl)ethynyl]4-iodothiophenes (3). To a solution of diisopropylamine (500 mL) were added 2,5-dialkynyl-3,4-diiodothiophene (10 g), bis(benzonitrilepalladium dichloride) (0.05 equiv), triphenylphosphine (0.1 equiv), and CuI (0.05 equiv). Degassed TMSA (1.1 equiv) was added to the solution at 0 °C. The mixture was stirred at 0 °C for 1 h and at room temperature for 20 h and refluxed for 1 h. Workup was the same as in the synthesis of 2. The mixture was separated by silica gel chromatography with hexane as eluant. 2,5-Dioctynyl-3-[(trimethylsilyl)ethynyl]-4-iodothiophene (3a). A yellow-brown colored oil (3.2 g, 34%) was obtained. IR 2906, 2224, 2156, 1450, 1448, 1350, 1322, 1251, 1003, 851, 766, 700, 655 cm-1; 1H NMR (CDCl3) δ 2.65 (t, 2 H), 2.43 (t, 2 H), 1.59 (m, 4 H), 1.45 (m, 4 H), 1.30 (m, 8 H), 0.892 (t, 3 H), 0.887 (t, 3 H), 0.25 (s, 9 H); 13C NMR (CDCl3) δ 130.97, 127.16, 124.84, 100.76, 100.73, 99.40, 98.97, 90.91, 74.54, 72.58, 31.28, 28.49, 28.35, 28.23, 22.54, 22.48, 19.91, 19.86, 14.06, 0.10. Anal. Calcd for C25H35ISSi (522.58): C, 57.50; H, 6.75. Found: C, 58.47; H, 7.07. 2,5-Ditetradecynyl-3-[(trimethylsilyl)ethynyl]-4-iodothiophene (3b). A yellow-brown oil (3.2 g, 34%) was obtained: 1H NMR (CDCl3) δ 2.49 (t, 2 H), 2.46 (t, 2 H), 1.61 (m, 4 H), 1.45 (m, 4 H), 1.27 (s, br, 32 H), 0.29 (t, 6 H), 0.28 (s, 9 H); 13C NMR (CDCl3) δ 131.23, 127.40, 125.08, 101.01, 99.65, 99.20, 91.13, 74.78, 72.83, 32.15, 29.88, 29.75, 29.71, 29.59, 29.34, 29.28, 28.63, 28.51, 22.92, 20.16, 20.09, 14.35, 0.15. Anal. Calcd for C37H59ISSi (690.89): C, 64.32; H, 8.61. Found: C, 64.14; H, 8.58. 2,5-Dioctynyl-3-ethynyl-4-iodothiophene (4a). To a mixture of methanol (100 mL), THF (100 mL), and H2O (1 mL) were added 10 g of 3a and KF (1.2 g). The solution was stirred at room temperature overnight, then diluted by H2O (100 mL), and extracted with methylene chloride (3 × 150 mL). The organic phases were combined and dried over MgSO4. After filtration the solvent was removed in vacuo, and the residue was separated by chromatography on silica gel with hexane. A yellow-brown oil (8.2 g 95.3%) was obtained: IR 3295, 2904, 2224, 2110, 1495, 1448, 1377, 1346, 1322, 1226, 1110, 775, 725, 654, 609 cm-1; 1H NMR (CDCl3) δ 3.39 (s, 1 H), 2.43 (t, 2 H), 2.47 (t, 2 H), 1.58 (m, 4 H), 1.43 (m, 4 H), 1.28 (m, 8 H), 0.88 (t, 3 H), 0.86 (t, 3 H); 13C NMR (CDCl3) δ 129.87, 128.40, 125.40, 101.23, 99.44, 90.59, 82.84, 78.72, 72.55, 31.50, 28.74, 28.68, 28.50, 28.44, 22.75, 20.14, 20.07, 14.27. Anal. Calcd for C22H27IS (450.40): C, 58.66; H, 6.04. Found: C, 59.32; H, 6.28. 2,5-Ditetradecynyl-3-ethynyl-4-iodothiophene (4b). Compound 3b (2.8 g) and KF (1 g) were added to the solution of methanol (50 mL), THF (50 mL), and H2O (1 mL). The mixture was stirred at room temperature for 48 h and worked up and separated like 4a. A yellow-brown oil (2.31 g, 89%) was obtained: 1H NMR (CDCl3) δ 3.42 (s, 1 H), 2.48 (m, 4 H), 1.62 (m, 4 H), 1.46 (m, 4 H), 1.26 (s, br, 32 H), 0.90 (t, 6 H); 13C NMR (CDCl3) δ 129.99, 128.46, 125.46, 101.30, 99.49, 90.59, 82.84, 78.80, 74.68, 72.57, 32.16, 29.89, 29.85, 29.75, 29.59, 29.32, 29.09, 29.04, 28.57, 28.50, 22.92, 20.17, 20.09, 14.35. Anal. Calcd for C34H51IS (618.70): C, 66.00; H, 8.31. Found: C, 66.10; H, 8.45. 2,5-Bis(2-hydroxy-2-methyl-3-butynyl)-3-ethynyl-4-iodothiophene (4c). To a solution of diisopropylamine (250 mL) were added 2c (5 g, 0.01mol), bis(benzonitrile)palladium dichloride (0.08 g, 0.02 equiv), triphenylphosphine (0.11 g, 0.04 equiv), and CuI (0.04 g, 0.02 equiv). Trimethylsilylacetylene (1.5 mL, 1.04 equiv) was added by syringe to the above solution at 0 °C. The mixture was stirred at 0 °C for 1 h, at room temperature for 24 h and at 60 °C for 8 h. After cooling to room temperature, the mixture was filtered. The solvent was removed in vacuo. The residue was dissolved in a mixture of THF (100 mL), methanol (100 mL), and H2O (1 mL). Excess KF was added, and the mixture was stirred at room temperature for 20 h. The solution was diluted by adding H2O (100 mL) and extracted with methylene chloride (3 × 100 mL). The extracts were combined and dried over MgSO4. The crude

Chem. Mater., Vol. 11, No. 11, 1999 3055 product was purified on silica gel column with hexane/ethyl acetate (2/1) as the eluant. White solid 4c (1.478 g, 37%) was obtained: mp 134-135 °C; 1H NMR (CDCl3) δ 3.48 (s, 1H), 2.08 (s, br, 2H), 1.63-1.64 (d, 12H); 13C NMR(CDCl3) δ 131.33, 127.64, 124.94, 103.82, 102.16, 92.46, 83.77, 83.72, 78.22, 76.24, 73.90, 66.11, 66.05, 31.38. Anal. Calcd for C16H15ISO2 (398.24): C, 48.25; H, 3.80. Found: C, 48.16; H, 3.70. 2,5-Bis[(trimethylsilyl)ethynyl]-3-ethynyl-4-iodothiophene (4d). To 50 mL of THF were added 2d (0.5 g, 0.95 mmol), bis(triphenylphosphine)palladium dichloride (0.033 g, 0.05 equiv), and ethynyltributyltin (0.29 mL, 0.95 mmol). The mixture was stirred at room temperature for 24 h and at 50 °C for 24 h. A light yellow solid (0.179 g, 44.2%) was obtained: mp 153-154 °C; 1H NMR (CDCl3) δ 3.49 (s, 1H), 0.27-0.29 (d, 18H); 13C NMR (CDCl3) δ 131.85, 128.06, 125.53, 106.37, 104.69, 97.44, 95.22, 92.83, 83.89, 78.24, 0.06. Anal. Calcd for C16H19ISSi2 (426.45): C, 45.06; H, 4.49. Found: C, 45.11; H, 4.52. Tris(2,5-dialkynylthieno)cyclotriynes (5). To a solution of diisopropylamine (50 mL) were added 2,5-dialkynyl-3ethynyl-4-iodothiophene (1 g), bis(dibenzyldeneacetone)palladium(0), Pd(dba)2 (0.05 equiv), triphenylphosphine (0.1 equiv), and CuI (0.05 equiv). The mixture was stirred at 0 °C for 1 h and refluxed for 6 h. The white solid was filtered out and washed with CH2Cl2 (3 × 10 mL). The filtrates were combined and the solvent was removed in vacuo. The residue was dissolved in methylene chloride (50 mL) and washed with dilute HCl, water and dried over MgSO4. Tris(2,5-dioctynylthieno)cyclotriyne (5a). The mixture was chromatographed on silica gel using hexane/CH2Cl2 (20/ 1) as eluant. A white solid (0.184 g, 25.6%) was obtained: mp 74-75 °C; IR (neat) 2219, 1461, 1263, 737 cm-1; 1H NMR (CDCl3) δ 2.47 (t, 12 H), 1.64 (quintet, 12 H), 1.43 (m, 12 H), 1.33 (m, 24 H), 0.90 (t, 18 H); 13C NMR (CDCl3) δ 126.68, 125.45, 100.35, 88.94, 72.94, 31.58, 29.03, 28.84, 22.77, 20.45, 14.25. C66H78S3 (967.46): FD-MS m/z ) 966 (M+). Anal. Calcd for C66H78S3: C, 81.93; H, 8.12. Found: C, 82.88; H, 8.72. Tris(2,5-ditetradecynylthieno)cyclotriyne (5b). Preparative TLC was used to separate the mixture with hexane/ benzene (5:1) as eluant. A white solid (0.115 g, 13%) was obtained: mp 26 °C; IR (neat) 2220, 1463, 1264, 730 cm-1; 1H NMR (CDCl3) δ 2.46 (t, 12 H), 1.65 (quintet, 12 H), 1.43 (m, 12 H), 1.27 (s, br, 96 H), 0.89 (t, 18 H); 13C NMR (CDCl3) δ 126.71, 125.65, 100.35, 88.95. 72.96, 32.17, 29.89, 29.78, 29.71, 29.61, 29.37, 28.88, 22.93, 20.45, 14.36. (1472.4); FDMS found 1470 (M+). Anal. Calcd for C102H150S3: C, 83.20; H, 10.27. Found: C, 83.09; H, 10.23. Tris[2,5-bis(2-hydroxy-2-methyl-3-butynyl)thieno]cyclotriyne (5c). The product was purified by chromatography on silica gel with ethyl acetate/hexane (2:1) as eluant. A white solid (0.065 g, 1%) was obtained, which decomposed on heating: IR (neat) 3314, 2913, 2863, 2198, 1458, 1373, 732 cm-1; 1H NMR (DMSO) δ 5.89 (s, 6H), 1.51 (s, 36H); 13C NMR (DMSO) δ 125.36, 124.68, 107.13, 88.44, 71.75, 64.24, 31.15. (811.03 for C48H42S3O6); FDMS found 810 (M+); C48H42S3O63H2O (865.06): Anal. Calcd for C48H42S3O63H2O: C, 66.64; H, 5.59. Found: C, 66.61; H, 5.17. Tris[2,5-bis[(trimethylsilyl)ethynyl]thieno]cyclotriyne (5d). The mixture was separated on a silica gel column with hexane/CH2Cl2 (100:1). A white solid (0.0339 g, 5%) was obtained: IR (neat) 2948, 2150, 1513, 1401, 1252, 854 cm-1; 1H NMR (CDCl ): δ 0.24 (s, 54H); 13C NMR (CDCl ) δ 126.97, 3 3 125.87, 106.77, 95.93, 89.41, 0.06; FDMS found 894 (m+). Anal. Calcd for C48H54S3Si6 (895.63): C, 64.37; H, 6.08. Found: C, 63.98; H, 6.34. 1,2-Didodecenoxybenzene (6a). A solution of DMSO (30 mL) containing catechol (8.8 g, 0.08 mol) was deoxygenated by three freeze, pump, thaw, and fill cycles with nitrogen. Deoxygenated 1-bromododecane (40 mL, ∼0.168 mol) and K2CO3 (25 g, 0.18 mol) were added. The mixture was stirred at 100 °C under a nitrogen atmosphere for 9 h. After the mixture was cooled to room temperature, 100 mL of water and 40 mL of methylene chloride were added. The organic layer was separated out, and the aqueous layer was extracted with CH2Cl2 (3 × 10 mL). The combined organic solutions were washed

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Chem. Mater., Vol. 11, No. 11, 1999

with water (2 × 50 mL) and dried over MgSO4. After filtration, the mixture was concentrated under vacuum and the excess 1-bromododecane was removed by distillation (65 °C, 0.1 mmHg). The resulting light-brown solid was crystallized from acetone. White needle crystals (14.6 g, 46.7%) of 5d were obtained: mp 40-41 °C; 1H NMR (CDCl3) δ 6.90 (s, 4H), 4.00 (t, 4H), 1.88-1.76 (m, 4H), 1.52-1.41 (m, 4H), 1.41-1.20 (s, br, 24H), 0.95-0.83 (t, 6H); 13C NMR (CDCl3) δ 149.48, 121.21, 114.35, 69.50, 32.14, 29.86, 29.81, 29.67, 29.58, 26.28, 22.90, 14.32. Anal. Calcd for C26H46O2: C, 79.94; H, 11.87. Found: C, 79.87; H, 11.80. 4,5-Didodecenoxy-1,2-diiodobenzene (7a). Mercuric acetate (6.52 g, 20.46 mmol) and 1,2-didodecenoxybenzene (4 g, 10.26 mmol) were added to methylene chloride (140 mL). The solution formed when 5 g of iodine (20.52 mmol), combined with 40 mL of CH2Cl2, was added dropwise to the above mixture at room temperature. To avoid using more solvent the remaining solid I2 was added to the reaction mixture directly. The resulting mixture was stirred at room temperature overnight and then filtered through Celite 545. The insoluble salts were washed with additional CH2Cl2. The combined filtrates were washed with an aqueous solution of Na2S2O3, a solution of NaHCO3 (saturated), H2O, brine, and H2O and then dried over MgSO4 overnight. After filtration, the solvent was removed in vacuo. A brown oil was obtained which solidified when cooled. White plate crystals could be obtained after recrystallized from ethanol or ethanol-acetone mixture. Purer product could only be obtained by silica chromatography (hexane/CH2Cl2 25:1). The yield is 70.3% (4.6 g): mp 52.553.5 °C; 1H NMR (CDCl3) 7.25 (s, 2H), 3.93 (t, 4H), 1.85-1.72 (m, 4H), 1.5-1.37 (m, 4H), 1.37-1.1 (s, br, 24H), 0.89 (t, 6H); 13C NMR (CDCl ) δ 150.02, 124.08, 96.19, 69.72, 32.13, 29.80, 3 29.76, 29.55, 29.27, 26.14, 22.90, 14.32. Anal. Calcd for C26H44I2O2: C, 48.61; H, 6.90. Found: C, 48.57; H, 6.95. 4,5-Didodecenoxy-2-ethynyl-1-iodobenzene (8a). 4,5Didodecenoxy-1,2-diiodobenzene (1.28 g, 2 mmol), Ph3P (0.021 g, 0.08 mmol), Pd(PhCN)2Cl2 (0.016 g, 0.04 mmol), and CuI (0.19 g, 1 mmol) were added to a 100-mL flask. Diisopropylamine (25 mL) and degassed trimethysilylacetylene (1.08 mL, 2.08 mmol) were added to the mixture via syringe. The mixture was stirred at room temperature for 1 h and 70 °C for 17 h. After the mixture was filtered, the solution the solvent was removed by vacuum. The residue was dissolved in a mixture of THF (50 mL), MeOH (100 mL), and H2O (0.5 mL). Excess KF was added, and the mixture was stirred overnight in the dark. Water (100 mL) and CH2Cl2 (50 mL) were added, and the pH of the solution was adjusted to about 7 with HCl. The aqueous portion was separated and washed with CH2Cl2 (2 × 15 mL). The combined organic extracts were washed with H2O (2 × 50 mL) and then dried over MgSO4. The solids were filtered out, and the solvent was removed in vacuo. The product was chromatographed on a column of silica gel (hexane/CH2Cl2 10:1) to give the white solid 8a (0.55 g, 50%): mp 46-47 °C; 1H NMR (CDCl3) δ 7.22 (s, 1H), 7.00 (s, 1H), 4.0-3.93 (m, 4H), 1.88-1.75 δ 150.63, 149.14, 123.09, 120.88, 117.99, 89.85, 85.71, 79.22, 69.56, 32.12, 29.80, 29.76, 29.55, 29.25, 26.15, 22.89, 14.32. Anal. Calcd for C28H45IO2: C, 62.25; H, 8.33. Found: C, 62.55; H, 8.58. Tris(4,5-didodecenoxyphenyl)cyclotriyne (9a) and tetrakis(4,5-didodecenoxyphenyl)cyclotetrayne (10a). Under an atmosphere of argon, 4,5-didodecenoxy-2-ethynyl-1iodobenzene (1.08 g, 2 mmol) and t-BuOK (0.25 g, 2.2 mmol) were mixed in pyridine (25 mL). The mixture was stirred at room temperature for 1 h and then CuI (0.25 g, 2.5 mmol) was added. The mixture was refluxed for 24 h and filtered. Solvent was removed by vacuum. The organic residue was taken up in CH2Cl2 (50 mL), washed with water (2 × 50 mL), and dried over MgSO4. After the solids were filtered out, the solvent was removed in vacuo. The product was chromatographed with silica gel (hexane/CH2Cl2 5:1) to give the yellow trimer 9a (0.17 g, 17%) and the light brown sticky tetramer 10a (0.12 g, 12%). Data for tris(4,5-didodecenoxyphenyl)cyclotriyne (9a): Mp 65 °C; IR (neat) 2919, 2849, 2204, 1590, 1500, 1488, 1348, 1224, 1067, 1012, 858, 722 cm-1; 1H NMR (CDCl3) δ 6.73 (s, 6H), 3.95 (t, 12H), 1.80 (quintet, 12H), 1.45 (m, 12H), 1.30 (s,br,

Zhang et al. 72H), 0.89 (t, 18H); 13C NMR (CDCl3) δ 149.27, 119.87, 115.81, 92.06, 69.21, 32.12, 29.78, 29.57, 29.32, 26.19, 22.90, 14.33; 1 H NMR (C6D6) δ 7.04 (s, 6H), 3.67 (t, 12H), 1.64 (quintet, 12H), 1.28 (s, br, 84H), 0.93 (t, 18H); 13C NMR (C6D6) δ 150.35, 121.12, 116.53, 93.50, 69.26, 32.72, 30.42, 30.19, 29.94, 26.79, 23.50, 14.74. FDMS found 1236 (M+). Anal. Calcd for C84H132O6: C, 81.50; H, 10.75. Found: C, 80.96; H, 10.75. Data for tetrakis(4,5-didodecenoxyphenyl)cyclotetrayne (10a): IR (neat) 2924, 2853, 2211, 1594, 1511, 1467, 1372, 1228, 1091, 860, 721 cm-1; 1H NMR (CDCl3) δ 7.00 (s, 8H), 3.98 (t, 16H), 1.82 (quintet, 16H), 1.45 (m, 16H), 1.30 (s, br, 96H), 0.88 (t, 24H); 13C NMR (CDCl3) δ 149.09, 118.94, 116.67, 89.91, 69.35, 32.13, 29.78, 29.56, 29.30, 26.18, 22.90, 14.33. FDMS found 1548 (M+). Anal. Calcd for C112H176O8: C, 81.50; H, 10.57. Found: C, 81.52; H, 10.85. 1,2-Ditetradecenoxybenzene (6b). A solution of DMSO (30 mL) containing catechol (8.8 g, 0.08 mol) was deoxygenated by three freeze, pump, thaw, and fill cycles. Deoxygenated 1-bromotetradecane (50.6 mL, ∼0.17 mol) and K2CO3 (25 g, 0.18 mol) were added to the above solution. The mixture was stirred at 100 °C under a nitrogen atmosphere for 8 h. After the mixture was cooled to room temperature, 100 mL of water and 40 mL of methylene chloride were added. The organic layer was separated and the aqueous layer was extracted with CH2Cl2 (3 × 10 mL). The combined organic solutions were washed with water (2 × 50 mL) and dried over MgSO4. After filtration, the mixture was concentrated under vacuum. The product was recrystallized twice from acetone. White needlelike crystals of 6b (23.5 g, 58.5%) were obtained: mp 53.554.5 °C; 1H NMR (CDCl3) δ 6.90 (s, 4H), 4.00 (t, 4H), 1.8 (m, 4H), 1.55-1.42(m, 4H), 1.42-1.2 (s, br, 40H), 0.90(t, 6H); 13C NMR (CDCl3) δ 149.49, 121.22, 114.38, 69.51, 32.16, 29.93, 29.82, 29.68, 29.59, 26.28, 22.92, 14.33. Anal. Cald for C34H62O2: C, 81.29; H, 12.34. Found: C, 81.39; H, 12.41. 4,5-Ditetradecenoxy-1,2-diiodobenzene (7b). 1,2-Ditetradecenoxybenzene (15.07 g, 30 mmol) and mercuric acetate (20.1 g, 63 mmol) were added to methylene chloride (350 mL). The solution formed when 16 g of iodine (63 mmol) is combined with 250 mL of CH2Cl2 was added dropwise to the above mixture at room temperature. To avoid using more solvent the remaining solid I2 was added to the reaction mixture directly. The resulting mixture was stirred at room temperature for 5 h and then filtered through Celite 545. The insoluble salts were washed with additional CH2Cl2. The combined filtrates were washed with aqueous Na2S2O3, aqueous NaHCO3 (saturated), H2O, brine, and H2O and then dried over MgSO4 overnight. After filtration, the solvent was removed in vacuo. A brown oil was obtained which solidified when cooling. White plate crystals of 7b (16.85 g, 74.45%) were obtained after two recrystallizations from ethanol: mp 67-68 °C; 1H NMR (CDCl3) δ 7.25 (s, 2H), 3.93 (t, 4H), 1.8 (m, 4H), 1.52-1.4 (m, 4H), 1.4-1.25 (s, br, 40H), 0.89 (t, 6H); 13C NMR (CDCl3) δ 149.96, 123.93, 96.17, 69.66, 32.15, 29.93, 29.82, 29.6, 29.26, 26.14, 22.92, 14.35. Anal. Calcd C34H60I2O2: C, 54.11; H, 8.01. Found: C, 54.20; H, 8.05. 4,5-Ditetradecenoxy-2-ethynyl-1-iodobenzene (8b). 4,5Ditetradecenoxy-1,2-diiodobenzene (11.3 g, 15 mmol), Ph3P (0.24 g, 0.9 mmol), Pd(PhCN)2Cl2 (0.12 g, 0.3 mmol), and CuI (2.86 g, 15 mmol) were added to a 500-mL flask. Diisopropylamine (300 mL) and degassed trimethysilylacetylene (2.2 mL, 15.6 mmol) were added to the mixture via syringe. The mixture was stirred at room temperature for 1 h and at 70 °C for 14 h. After the mixture was filtered, the solvent was removed by vacuum. The residue was dissolved in a mixture of THF (150 mL), MeOH (300 mL), and H2O (2 mL). Excess KF was added and the mixture was stirred overnight in the dark. Water (150 mL) and CH2Cl (150 mL) were added and the pH of the solution was adjusted to about 7 with HCl. The aqueous portion was separated and washed with CH2Cl2 (2 × 30 mL). The combined organic extracts were washed with H2O and then dried over MgSO4. The solids were filtered out and the solvent was removed in vacuo. The product was chromatographed on a column of silica gel (hexane/CH2Cl2 40:1) to give the white solid 8b (2.5 g, 25%): mp 68-69 °C; 1H NMR (CDCl3) δ 7.21 (s, 1H), 6.99 (s, 1H), 3.9-3.29 (m, 4H), 1.9-1.75 (m,

Synthesis and Complexation of Cyclotriynes 4H), 1.52-1.4 (m, 4H), 1.4-1.2 (s, br, 40H), 0.89 (t, 6H); 13C NMR (CDCl3) δ 150.58, 149.09, 122.98, 120.82, 117.88, 89.84, 85.70, 69.55, 32.15, 29.93, 29.83, 29.6, 29.26, 26.14, 22.92, 14.35. Anal. Calcd for C36H61IO2: C, 66.29; H, 9.43. Found: C, 66.14; H, 9.15. Tris(4,5-ditetradecenoxyphenyl)cyclotriyne (9b) and Tetrakis(4,5-ditetradecenoxyphenyl)cyclotetrayne (10b). Under an atmosphere of argon, 4,5-ditetradecenoxy-2-ethynyl1-iodobenzene (0.98 g, 1.5 mmol) and t-BuOK (0.185 g, 1.65 mmol) were mixed in pyridine (25 mL). The mixture was stirred at room temperature for 1 h and then CuI (0.17 g, 1.65 mmol) was added. The mixture was refluxed for 24 h and filtered. Solvent was removed by vacuum. The organic residue was taken up by CH2Cl2 (50 mL) and washed with water (2 × 50 mL), and dried over MgSO4. After the solids were filtered out, solvent was removed in vacuo. The product was chromatographed with silica gel (hexane/CH2Cl2 3;1) to give the yellow trimer 9b (0.115 g, 16%) and the light brown sticky tetramer 10b (0.13 g, 16.5%). Data for tris(4,5-ditetradecenoxyphenyl)cyclotriyne 9b: Mp 67-68 °C; FT-IR (neat) 2921, 2850, 2210, 1591, 1511, 1350, 1229, 1072, 856, 720 cm-1; 1H NMR (CDCl3) δ 6.72 (s, 6H), 3.96 (t,12H), 1.81 (quintet, 12H), 1.45 (m, 12H), 1.27 (s, br, 120H), 0.89 (t, 18H); 13C NMR (CDCl3) δ 149.29, 119.90, 115.87, 92.05, 69.23, 32.16, 29.94, 29.85, 29.61, 26.21, 22.92, 14.34; FDMS found 1572 (M+). Anal. Calcd for C108H180O6: C, 82.38; H, 11.52. Found: C, 82.43; H, 11.64. Data for tetrakis(4,5-ditetradecenoxyphenyl)cyclotetrayne 10b: FT-IR (neat) 2923, 2852, 2208, 1594, 1511, 1467, 1372, 1228, 1090, 861, 720 cm-1; 1H NMR (CDCl3) δ 7.00 (s, 8H), 3.98 (t, 16H), 1.82 (quintet, 16H), 1.45 (m, 16H), 1.27 (s, br, 160H), 0.89 (t, 24H); 13C NMR (CDCl3) δ 149.12, 118.97, 116.73, 89.93, 69.40, 32.16, 29.93, 29.85, 29.60, 29.33, 26.20, 22.92, 14.34; FDMS found 2096 (M+). Anal. Calcd for C144H240O8: C, 82.38; H, 11.52. Found: C, 82.21; H, 11.43. Synthesis of The Ni(0) Complex of Tris[4,5-bis(dodecyloxy)phenyl]cyclotriyne 11. A solution containing 0.124 g (0.1 mmol) of tris[4,5-bis(dodecyloxy)phenyl]cyclotriyne in 15 mL of benzene and a solution containing 0.28 g Ni(COD)2 in 15 mL of benzene were combined in the drybox. A deep blue

Chem. Mater., Vol. 11, No. 11, 1999 3057 solution was obtained. The reaction mixture was stirred overnight and filtered. The volatiles were removed in vacuo leaving the purple solid 11: yield 0.121 g, 93%; mp 81-82 °C; IR (Nujol) 1963, 1584, 1213, 1042, 722 cm-1; 1H NMR (C6D6) δ 7.36 (s, 6H), 3.76 (t, 6.4 Hz, 12H), 1.69 (m, 12H), 1.29 (br, 84H), 0.94 (t, 6.1-6.7 Hz, 18H); 13C NMR (C6D6) δ 149.69, 136.32, 113.57, 108.54, 69.34, 32.73, 30.43, 30.20, 29.97, 26.85, 23.49, 14.74; FDMS found 1294 (M+). Anal. Calcd for C84H132O6Ni: C, 77.81; H, 10.26. Found: C, 76.28; H, 10.25. Synthesis of the Nonacarbonyltricobalt Complex of Tris[4,5-bis(dodecyloxy)phenyl]cyclotriyne 12. An ether solution (15 mL) of tris[3,4-bis(dodecyloxy)phenyl]cyclotriyne (0.124 g, 0.1 mol) was added to an ether solution (15 mL) of Co2(CO)8 (0.072 g, 0.2 mol) in the drybox, and the mixture was stirred overnight. The reaction mixture was filtered and the volatiles were removed in vacuo leaving a black sticky solid: yield 0.16 g, 92.7%; IR (Nujol) 2096, 2052, 2027 (sh), 1973, 1864, 1045, 724 cm-1. The FDMS spectra only gave an ion peak of a tricobalt complex (C93H132O15Co3) at 1665. Anal. Calcd for C93H132O15Co4: C, 64.72; H, 7.71. Found: C, 64.84; H, 8.03.

Acknowledgment. This material is based upon work supported by the National Science Foundation under grant CHE 97-08181, the NASA Lewis Research Center, and The Ohio Board of Regents. We thank Satyendra Kumar of the Kent State Liquid Crystal Institute for evaluation of liquid crystal properties by optical and X-ray techniques and David B. McConnville and Richard S. Simons for the partial X-ray crystal structure of 5a. D.Z. thanks Lan Li for help with NMR measurements. W.J.Y. and C.T. thank Professors Franc¸ ois Diederich and Peter Chen for the opportunity to spend their sabbaticals at ETH Zurich, the Swiss National Science Foundation for support and Jessica Tessier Youngs for useful discussions. CM990046V