CRYSTAL GROWTH & DESIGN
Three-Dimensional Coordination Polymer of Silver(I) with Bridging Ligand Hexakis(4-pyridyl)[3]radialene Kouzou Matsumoto,* Yukako Harada, Nao Yamada, Hiroyuki Kurata, Takeshi Kawase, and Masaji Oda Department of Chemistry, Graduate School of Science, Osaka UniVersity, Toyonaka, Osaka 560-0043, Japan
2006 VOL. 6, NO. 5 1083-1085
ReceiVed February 13, 2006; ReVised Manuscript ReceiVed March 24, 2006
ABSTRACT: This paper describes the synthesis of hexakis(4-pyridyl)[3]radialene and the crystal structures of its complexes. Due to their structural diversity and fascinating properties, coordination polymers have attracted considerable attention. From the standpoint of crystal engineering, the title compound will be regarded as a useful tecton since the pyridyl groups are attached to the [3]radialene core. The title compound formed a complex with two molecules of resorcinol. In this complex, the double hydrogen bonding between the title compound and resorcinol is observed. Deformation of the title compound is observed because of the binding of resorcinol molecules. A silver(I) complex of the title compound was also obtained as reddish crystals. Notably, the crystal structure of the silver(I) complex features a three-dimensional coordination polymer. The composition of the crystal is 1:1 with respect to the title compound and silver(I) atoms including the solvent molecules of one DMSO and one methanol. Four of the six nitrogen atoms are coordinated to the silver(I) atom and the other two pyridyl groups are free from coordination. The coordination geometry of the silver(I) atom is distorted tetrahedral. To the best of our knowledge, this is the first example of a three-dimensional coordination polymer of a [3]radialene-based bridging ligand. Coordination polymers have infinite frameworks constructed from metal ions and organic ligands.1 Due to their structural diversity and fascinating properties such as porous function, magnetism, and conductivity, coordination polymers have attracted considerable attention in the last two decades. Since the structural diversity of coordination polymers mainly comes from the geometry and topology of the organic ligands, many kinds of organic ligands are synthesized and intensively investigated for supramolecular architecture. Recently, we reported the synthesis of hexakis(2pyridyl)- and hexakis(3-pyridyl)[3]radialene,2 1a and 1b, respectively, in the course of our studies on radialenes (Chart 1).3 Due to its unique structure and remarkable redox properties, [3]radialene4 has attracted considerable attention from both theoretical and experimental points of view.5 When these hexapyridyl[3]radialenes are regarded as tectons in crystal engineering, they are interesting molecules as a component of supramolecular complexes or coordination polymers. Indeed, Steel and Sumby showed three kinds of novel and interesting coordination modes of 1a in its silver(I) complexes, in which the coordination modes are controlled by the counteranion.6 In this context, hexakis(4-pyridyl)[3]radialene 1c would also be a promising molecule as a multiple hydrogen bonding acceptor or bridging ligand to form coordination polymers. In contrast to 1a and 1b, the 4-pyridyl derivative 1c would provide specific directions of the sp2 nitrogen atoms regardless of the rotation of the pyridyl groups; the central [3]radialene core makes the six pyridyl groups take the conformation of three sets of two pyridyl groups where the distance between sp2 nitrogen atoms in each set is about 4 Å. Here we report the synthesis of 1c and the crystal structures of its complexes with resorcinol and with silver(I) perchlorate. The structure of the silver(I) complex of 1c features a three-dimensional (3D) coordination polymer, which has attracted considerable attention in recent years.7 To the best of our knowledge, this is the first example of a three-dimensional coordination polymer of a [3]radialene-based bridging ligand. Similar to other hexaaryl[3]radialenes, the radialene 1c was also synthesized by the reaction of bis(4-pyridyl)methyl anion, generated from bis(4-pyridyl)methane8 by treatment of 1.0 equiv of lithium diisopropylamide (LDA) with tetrachlorocyclopropene (TCCP)9 followed by oxidation with oxygen (Scheme 1).10 Red single crystals appeared from a solution of 1c in methanol-ether in the presence of three molar amounts of resorcinol. An elemental analysis indicated the stoichiometry of 1c and resorcinol to be 1:2.11 Figure * Corresponding author: Phone: +81 6 6850 5386. Fax: +81 6 6850 5387. E-mail:
[email protected].
Chart 1.
Scheme 1.
Hexapyridyl[3]radialenes.
Synthesis of Hexakis(4-pyridyl)[3]radialene
1 shows the ORTEP drawing of the complex of 1c with resorcinol (1c‚(resorcinol)2). The complex has a C2 axis along the C1-C3 bond. The cyclopropane ring C1-C2-C3 is almost an equilateral triangle. Two resorcinol molecules are bound to 1c through double hydrogen bonds. The atomic distances of N1-O2 and N2-O1 are 2.768(1) and 2.802(1) Å, respectively. The formation of the complex of 1c with resorcinol would be due to the favorable geometry of the pyridyl group in 1c for the construction of the double hydrogen bonding with resorcinol. It should be noted that the atomic distance between N1 and N2 is 4.04 Å, whereas the distance between N3 and N3* is 4.64 Å; the deformation of 1c is induced by the complexation of resorcinol. Consequently, N3 and N3* are free from complexation because of this deformation of 1c. Any other short contacts are not observed for N3 and N3* atoms. A single crystal of the silver(I) complex of 1c suitable for X-ray crystallographic analysis was also obtained from an equimolar mixture of 1c and silver(I) perchlorate in a DMSO solution by the technique of slow vapor diffusion with methanol. The ratio of 1c and silver(I) perchlorate in the crystal was 1:1, including the solvent molecules of one DMSO and one methanol molecule per one molecule of 1c, which was also confirmed by elemental analysis.12 The ORTEP drawing of the coordination polymer 1c‚AgClO4‚ DMSO‚MeOH is shown in Figure 2. Radialene 1c acts as a tetradentate ligand: four of the six pyridyl groups are coordinated to the silver(I) ion and other two pyridyl groups are free from coordination. No short contacts are observed between noncoordinated nitrogen atoms and solvate molecules or perchlorate ions. The central cyclopropane ring C1-C2-C3 is almost an equilateral
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1084 Crystal Growth & Design, Vol. 6, No. 5, 2006
Figure 1. ORTEP drawing of the complex 1c‚(resorcinol)2 (50% probability). The other resorcinol molecule is omitted for clarity. Selected bond lengths (Å) and angles (deg): C1-C2 1.435(2), C2-C2* 1.436(2), C1C3 1.360(3), C2-C4 1.359(2), N1‚‚‚O2 2.768(1), N2‚‚‚O1 2.802(1), C2C1-C2* 60.0(1), C1-C2-C2* 59.98(6).
Communications
Figure 3. One-dimensional polymeric chain of the dimeric units [1c2‚Ag2]2+ in silver(I) complex of 1c. Ag1-N2 bonds are shown by ball-and-stick.
Figure 4. Interchain interaction of the dimeric units [1c2‚Ag2]2+ in silver(I) complex of 1c. The dimeric units shown by reddish ball-and-stick are linked with four neighboring dimeric units by Ag1-N5 bond. Ag1-N5 bonds are marked by red arrows.
Figure 2. ORTEP drawing of the silver(I) complex of 1c (50% probability). DMSO and methanol molecules are omitted for clarity. Selected bond lengths (Å) and angles (deg): Ag1-N1 2.300(4), Ag1-N2* 2.462(4), Ag1N5′ 2.378(4), Ag1-N6′′ 2.571(4), C1-C2 1.424(5), C1-C3 1.430(5), C2C3 1.423(5), C1-C4 1.359(5), C2-C5 1.358(5), C3-C6 1.355(5), N1Ag1-N2* 103.3(1), N1-Ag1-N5′ 131.2(1), N1-Ag1-N6′′ 128.8(2), N2*-Ag1-N5′ 101.4(1), N2*-Ag1-N6′′ 89.0(2), N5′-Ag1-N6′′ 92.8(2), C2-C1-C3 59.8(2), C1-C2-C3 60.3(2), C1-C3-C2 59.9(2).
triangle whose sides are approximately 1.42 Å, as observed in 1c‚ (resorcinol)2. Each silver(I) ion is coordinated by four nitrogen atoms, each of which is derived from a different ligand. The coordination geometry of the silver(I) ion can be regarded as distorted tetrahedral. Otherwise, taking a weak contact between Ag1‚‚‚O2 (3.01 Å) into account, it may be regarded as distorted trigonal bipyramidal. The distance between the sp2 nitrogen atoms in the facing pyridyl rings are in the range of 3.92-4.07 Å; no remarkable deformation of 1c is observed. The coordination pattern between 1c and the silver(I) ion is somewhat complicated. At first, two molecules of 1c are bridged by two Ag1-N1 bonds and two Ag1-N6 bonds to form a dimeric unit ([1c2‚Ag2]2+). In this dimeric unit, the distance between the silver atoms (Ag1‚‚‚Ag1′′) is approximately 5.67 Å. The perchlorate ions locate the outside of the dimeric unit neighboring the silver atoms. Second, these dimeric units are linked by two Ag1-N2 bonds to form a one-dimensional polymeric chain along the a axis
(Figure 3). Third, each chain is linked by Ag1-N5 bonds to form a 3D coordination polymer (Figure 4). Consequently, each unit [1c2‚ Ag2]2+ is bound to the six neighboring units with eight coordination bonding to form a three-dimensionally extended coordination polymer. The solvated DMSO and MeOH molecules fill the void within the coordination polymer. In conclusion, we have synthesized hexakis(4-pyridyl)[3]radialene 1c by the application of our procedure for hexaaryl[3]radialenes. Radialene 1c can act as a useful multiple bridging ligand for the silver(I) ion whose coordination polymer forms a 3D framework. The formation of other metal complexes, in which 1c exhibits a different coordination mode, and complexes with the other [3]radialenes involving other heteroaromatics such as thiazole and pyrazole are now in progress. Acknowledgment. This work was supported in part by the 21st Century COE Program, Japanese Government (Creation of Integrated EcoChemistry). Supporting Information Available: Experimental section and crystal data in CIF format. This material is available free of charge via the Internet at http://pubs.acs.org.
References (1) For recent reviews on coordination polymers, see: (a) Janiak, C. Dalton Trans. 2003, 2781-2804. (b) Kitagawa, S.; Noro, S. In ComprehensiVe Coordination Chemistry II; McCleverty, J. A., Meyer, T. J., Eds.; Elsevier: Oxford, England, Tokyo, 2004; Vol. 7, Chapter 5, pp 231-261. (c) Kitagawa, S.; Uemura, K. Chem. Soc. ReV. 2005, 34, 109-119.
Communications (2) Matsumoto, K.; Harada, Y.; Kawase, T.; Oda, M. Chem. Commun. 2002, 324-325. (3) (a) Enomono, T.; Kawase, T.; Kurata, H.; Oda, M. Tetrahedron Lett. 1997, 38, 2693-2696. (b) Enomoto, T.; Nishigaki, N.; Kurata, H.; Kawase, T.; Oda, M. Bull. Chem. Soc. Jpn. 2000, 73, 2109-2114. (4) For reviews on radialene, see: (a) Hopf, H.; Maas, G. Angew. Chem., Int. Ed. Engl. 1992, 31, 931-954. (b) Maas, G.; Hopf, H. In The Chemistry of Dienes and Polyenes; Rappoport, Z., Ed.; J. Wiley & Sons: Chichester, U.K., 1997; Vol. 1, Chapter 21, pp 927-977. (c) Hopf, H. Classics in Hydrocarbon Chemistry; Wiley-VCH: Weinheim, Germany, 2000; pp 290-300. (5) For recent examples, see: (a) Nielsen, M. B.; Schreiber, M.; Baek, Y. G.; Seiler, P.; Lecomte, S.; Boudon, C.; Tykwinski, R. R.; Gisselbrecht, J.-P.; Gramlich, V.; Skinner, P. J.; Bosshard, C.; Gu¨nter, P.; Gross, M.; Diederich, F. Chem.sEur. J. 2001, 7, 3263-3280. (b) Zhao, Y.; Campbell, K.; Tykwinski, R. J. Org. Chem. 2002, 67, 336-344. (c) Tobe, Y.; Umeda, R.; Iwasa, N.; Sonoda, M. Chem.s Eur. J. 2003, 9, 5549-5559. (d) Ho¨pfner, T.; Jones, P. G.; Ahrens, B.; Dix, I.; Ernst, L.; Hopf, H. Eur. J. Org. Chem. 2003, 25962611. (e) Kuwatani, Y.; Yamamoto, G.; Oda, M.; Iyoda, M. Bull. Chem. Soc. Jpn. 2005, 78, 2188-2208. (6) (a) Steel, P. J.; Sumby, C. J. Chem. Commun. 2002, 322-323. (b) Steel, P. J.; Sumby, C. J. Inorg. Chem. Commun. 2002, 5, 323-327. (7) For a review, see: Chen, C.-L.; Kang, B.-S.; Su, C.-Y. Aust. J. Chem. 2006, 59, 3-18. (8) Sepiol, J.; Soulen, R. L. J. Org. Chem. 1975, 40, 3791-3793. (9) Gaus, P. L.; Haim, A.; Johnson, F. J. Org. Chem. 1977, 42, 564565.
Crystal Growth & Design, Vol. 6, No. 5, 2006 1085 (10) Specral data for 1c: C36H24N6; orange crystals; mp > 260 °C (dec); MS (FAB) m/z 541.3 ([M + H]+); 1H NMR (270 MHz, CDCl3) δ 8.24 (dd, J ) 4.2, 1.6 Hz, 12H), 6.70 (dd, J ) 4.2, 1.6 Hz, 12H); 13C NMR (67.8 MHz, CDCl ) δ 148.92, 145.76, 124.27, 124.09, 3 119.41; UV-vis (CH2Cl2) λmax (log ) 450 (4.39). Anal. Calcd for C36H24N6: C, 79.98; H, 4.47; N, 15.55. Found: C, 80.04; H, 4.38; N, 15.52. (11) Crystal data for 1:2 complex of 1c and resorcinol 1c‚(resorcinol)2: C48H36N6O4, MW ) 760.85, monoclinic, space group C2/c (no. 15), a ) 18.001(7), b ) 13.615(6), c ) 16.927(6) Å, β ) 110.83(1)°, V ) 3877(9) Å3, Z ) 4, Dcalc ) 1.303 g‚cm-1, T ) 200 K. Of the 18 858 reflections that were collected, 4397 unique reflections were used in refinement. R1 ) 0.046 (3220 data, I > 2σ(I)), wR2 ) 0.124 (all data), GOF ) 1.10. Anal. Calcd for C48H36N6O4: C, 75.77; H, 4.77; N, 11.05. Found: C, 75.58; H, 4.83; N, 11.04. (12) Crystal data for the coordination polymer of 1c‚AgClO4‚DMSO‚ MeOH: C39H34N6AgClO6S, MW ) 858.12, monoclinic, space group P21/n (no. 14), a ) 11.147(2), b ) 25.605(4), c ) 13.295(3) Å, β ) 107.341(9)°, V ) 3622(4) Å3, Z ) 4, Dcalc ) 1.573 g‚cm-3, T ) 298 K. Of the 33 881 reflections that were collected, 8285 unique reflections were used in refinement. R1 ) 0.064 (6633 data, I > 2σ(I)), wR2 ) 0.174 (all data), GOF ) 1.11. Anal. Calcd for C39H34N6AgClN6O6S: C, 54.59; H, 3.99; N, 9.79. Found: C, 54.16; H, 3.89; N, 9.81.
CG060073F
