Coordination Polymers of 2, 5-Dihydroxybenzoquinone and

Jun 16, 2011 - 2,5-Dihydroxybenzoquinone (I, hereafter H2dhbq) and chloranilic acid (II, hereafter H2can) upon deprotonation provide dianionic ligands...
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Coordination Polymers of 2,5-Dihydroxybenzoquinone and Chloranilic Acid with the (10,3)-a Topology Brendan F. Abrahams,* Timothy A. Hudson, Laura J. McCormick, and Richard Robson* School of Chemistry, University of Melbourne, Victoria 3010, Australia

bS Supporting Information ABSTRACT: Crystalline compounds of general composition (NBu4)2[MII2(dhbq)3] (where M = Mn, Fe, Co, Ni, Zn, and Cd and dhbq2 is the dianion of 2,5dihydroxybenzoquinone) are obtained by reaction of the divalent metal acetate (or the sulfate in the case of Fe) with 2,5-diaminobenzoquinone and an excess of NBu4Br in aqueous solution at 115 °C in sealed tubes. The dhbq2 ligand is generated in situ by hydrolysis of the 2,5-diaminobenzoquinone. We have been unable to obtain these compounds in a crystalline form suitable for single crystal X-ray diffraction studies directly from H2dhbq itself. A structural feature common to this series is the presence of two interpenetrating [MII2(dhbq)3]2 coordination networks, each with the chiral (10,3)-a topology, with the two independent nets being of opposite hand—unprecedented circumstances for dhbq-based coordination polymers. Crystals of the same zinc compound as that obtained above from 2,5-diaminobenzoquinone can alternatively be obtained by in situ aerial oxidation of 1,2,4,5-tetrahydroxybenzene in the presence of Zn(OAc)2 and NBu4Br in aqueous methanol at room temperature. Analogous in situ aerial oxidation of 1,2,4,5tetrahydroxy-3,6-dichlorobenzene in the presence of Mn(OAc)2 and NBu4Br affords crystalline samples of the chloranilate (NBu4)2[MnII2(can)3], which contains two interpenetrating (10,3)-a [MnII2(can)3]2 networks of opposite hand.

2,5-D

ihydroxybenzoquinone (I, hereafter H2dhbq) and chloranilic acid (II, hereafter H2can) upon deprotonation provide dianionic ligands capable of chelating a single metal center to give mononuclear complexes.

They are capable also of bridging two metal centers to yield binuclear and oligomeric complexes as well as 1D, 2D, and 3D polymers. A feature of major interest in these systems is their ability to exist, after deprotonation, not only as the 2 anion but also as the relatively stable 1 or 3 radical anions, as well as r 2011 American Chemical Society

the 4 anion. Electrochemical studies of dhbq-bridged and canbridged binuclear complexes reveal that radical oxidation states of the organic bridges are easily achieved.1 Some of the longer term objectives of our group are to discover dhbq-based or canbased coordination polymers in which (a) some or all of the bridging ligands are in a radical state, or (b) both the metal centers and the bridging ligands carry unpaired electrons, or (c) both metal and ligand components are amenable to facile electron transfer. These various circumstances may lead to interesting and possibly useful electronic/magnetic properties. On the basis of the many structural studies of dhbq2 -based and can2 -based coordination polymers in the literature, we present here a very brief overview of the major structural types known at present. A number of 1D polymers (generally M2+/ can2 or M2+/dhbq2 ) are known in which the octahedral metal components of the chain carry two monodentate ligands such as H2O. If these two ligands are trans, a linear polymer results in which the dhbq2 or can2 components are essentially coplanar,2 whereas if the two are cis, a zigzag conformation is adopted.2c,3 Related zigzag polymers are formed when a single bidentate ligand occupies two cis positions.4 In some cases, neutral bridging ligands (other than can2 or dhbq2 ) link M/can or M/dhbq Received: May 10, 2011 Revised: June 8, 2011 Published: June 16, 2011 2717

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Figure 1. The (10,3)-a net.

chains together to generate sheets.2g,4c,5 Many 2D (Mn+)2(can2 )3 and (Mn+)2(dhbq2 )3 (n = 2 or 3) networks with the (6,3) topology (resembling chicken wire) have been described.6,7 Another structural type, that could legitimately be regarded as intermediate between the 1D chain and the 2D sheet, is the ladder-like arrangement, as seen in (LaIII)2(can)3(H2O)6 3 7H2O.7 We know of only three structures containing 3D M/can or M/ dhbq networks. One is AgI2(can), consisting of planar AgI2(can) strips, each connected to an infinite number of other identical strips, all inclined at ∼121° to the first.8 The remaining examples, viz., (H3O)[YIII(can)2] 3 8MeOH and ThIV(can)2(H2O)2 3 4H2O, have the diamond topology. 7 The reduced form of dhbq2 , C6H2O44 , acts as a bridge between HoIII centers in anionic coordination polymers of composition Na5[HoIII(C6H2O4)2] 3 7H2O;9 this network also has the diamond topology. It was noted some time ago10 that the topology adopted by networks consisting of octahedral metal centers that are tris chelated by planar bridging ligands such as dhbq2 or can2 is dictated by the distribution of their absolute configurations. If there is a regular alternation so that every Δ center is connected by dhbq2 or can2 bridges to three Λ centers and every Λ center is likewise connected to three Δ centers, a network with the 2D (6,3) topology must result. If, on the other hand, all the metal centers have the same absolute configuration, a 3D network with the intrinsically chiral (10,3)-a topology, shown in Figure 1, is favored. In this paper we report the formation and structural characterization of a new class of dhbq2 -based and can2 -based coordination polymers that have this (10,3)-a topology. We have so far been able to obtain these compounds in crystalline form suitable for single crystal X-ray diffraction studies only by in situ generation of dhbq2 and can2 from precursors such as 2,5diaminobenzoquinone (III), 1,2,4,5-tetrahydroxybenzene (IV), and 1,2,4,5-tetrahydroxy-3,6-dichlorobenzene (V). Under the reaction conditions used to generate the coordination polymers, III suffers in situ hydrolysis to dhbq2 , and IV or V are oxidized by air to dhbq2 or can2 , respectively. Crystalline compounds containing [MII2(dhbq)3]2 networks with (10,3)-a topology (M = Mn, Fe, Co, Ni, Zn, and Cd) are obtained by reaction of the divalent metal acetate (or the sulfate in the case of Fe) with III and an excess of NBu4Br in aqueous solution at 115 °C in sealed tubes.11 Crystals of the same compound containing [ZnII2(dhbq)3]2

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(10,3)-a networks such as that obtained above from III can alternatively be obtained by reaction in air of IV with Zn(OAc)2 and NBu4Br in aqueous methanol at room temperature;11 crystals containing [MnII2(can)3]2 (10,3)-a networks can similarly be obtained from V and NBu4Br in the presence of air.11 All of these compounds contain two independent (10,3)-a networks that interpenetrate in the manner discussed in more detail below. As already mentioned, the (10,3)-a net is intrinsically chiral; inspection of Figure 1 will reveal 4-fold helices, all in this case right-handed (or left as the case may be), running parallel to each of the cubic axes. We describe here in some detail the [FeII2(dhbq)3]2 system, which is representative of the entire group except for the Mn compound, which differs in only a minor respect described below. Figure 2a shows one of the two (10,3)-a [FeII2(dhbq)3]2 networks, as seen, for comparative purposes, from the same angle as that seen for the parent net of the same hand shown in Figure 1. The two independent [FeII2(dhbq)3]2 (10,3)-a networks are of opposite hand and interpenetrate as shown in Figure 2b. The NBu4+ cations, which are highly disordered, occupy regions close to but not exactly midway between the metal centers from two independent networks. A carbon atom adjacent to the nitrogen center is disordered over two symmetry-related sites, both of which lie on a 3-fold axis (or, in the case of the Mn network, pseudo-3-fold axes). The nitrogen center is therefore disordered over six equivalent sites, and the disorder associated with the remaining atoms (except for the single carbon atom lying on the axis) consequently becomes very complex (see Supporting Information). It appears as though the NBu4+ cations are playing an important stabilizing role in keeping the anionic networks as far apart as possible; we note that there are no close contacts between the two interpenetrating networks. All the compounds reported here are cubic (a = 22.1 22.8 Å) except for (NBu4)2[Mn2(dhbq)3], which is tetragonal (a = 23.4246(6), c = 21.3264(12) Å).12 The metal ligand connectivity in the Mn case is the same as that in all the cubic examples, with the Mn structure differing from the others in that there is minor compression along the tetragonal axis and expansion in the a and b directions. The reason for this distortion, albeit minor, of the network in (NBu4)2[Mn2(dhbq)3] remains a mystery to us, a mystery compounded by the fact that the Mn/ can compound is cubic. Elemental and thermogravimetric analyses indicate that (NBu4)2[M2(dhbq)3] (M = Mn or Cd) upon removal from the mother liquor is solvent-free while the other members of the group contain 1 1.5 molecules of water or 1 molecule of methanol (in the Mn/can case) per formula unit. The results presented here open the way for the generation of an extensive range of solid materials containing two independent, enantiomeric, and interpenetrating (10,3)-a nets of composition [(MII)2(can)3]2 and [(MII)2(dhbq)3]2 , where the framework metal M, as well as the countercation, can be varied widely. Preliminary work using the synthetic approaches described above and using countercations other than (NBu4)+ has yielded a number of products in the form of small crystals with the cubic unit cell and the cell dimensions (a = ∼22.2 Å) characteristic of the structure containing two interpenetrating (10,3)-a networks. The synthetic and structural results presented here represent a step on the way to the goal of using redox intercalation to generate frameworks in which all or a fraction of the bridging ligands (as well as the metal centers themselves) formally carry unpaired electrons. As an example illustrative of much wider general possibilities, we could envisage diffusing Na vapor into the network, thereby reducing some or all of the dhbq2 or can2 2718

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’ ACKNOWLEDGMENT The authors gratefully acknowledge support from the Australian Research Council. ’ REFERENCES

Figure 2. (a) One of the two [FeII2(dhbq)3]2 networks with (10,3)-a topology seen from the same angle as that for the parent net in Figure 1. (b) Two independent, enantiomeric, interpenetrating [FeII2(dhbq)3]2 networks.

components to the 3 radical state, while the Na+ cations formed concomitantly could be satisfactorily accommodated by favorable association with the readily accessible anionic oxygen centers of the framework ligands.

’ ASSOCIATED CONTENT

bS

Supporting Information. Crystallographic details, X-ray crystallographic information files (CIF), TGA, and selected figures. This material is available free of charge via the Internet at http://pubs.acs.org.

’ AUTHOR INFORMATION Corresponding Author

*B.F.A.: e-mail, [email protected]; phone, +61 3 8344 0341; fax, +61 3 9347 5180. R.R.: e-mail, [email protected]; phone, +61 3 8344 6469; fax, +61 3 9347 5180.

(1) (a) Ghumaan, S.; Sarkar, B.; Maji, S.; Puranik, V.; Fiedler, J.; Urbanos, F. A.; Jimenez-Aparicio, R.; Kaim, W.; Lahiri, G. K. Chem.— Eur. J. 2008, 14, 10816–10828. (b) Han, Y.-F.; Lin, Y.-J.; Jia, W.-G.; Jin, G.-X. Organometallics 2008, 27, 4088–4097. (c) Li, B.; Tao, J.; Sun, H.L.; Sato, O.; Huang, R.-B.; Zheng, L.-S. Chem. Commun. 2008, 2269–2271. (d) Ishikawa, R.; Kabir, M. K.; Adachi, K.; Nozaki, K.; Kawata, S. Chem. Lett. 2007, 36, 1116–1117. (e) Guo, D.; McCusker, J. K. Inorg. Chem. 2007, 46, 3257–3274. (f) Min, K. S.; DiPasquale, A. G.; Golen, J. A.; Rheingold, A. L.; Arif, A. M.; Miller, J. S. J. Am. Chem. Soc. 2007, 129, 2360–2368. (2) (a) Morikawa, S.; Yamada, T.; Kitagawa, H. Chem. Lett. 2009, 38, 654–655. (b) Yamada, T.; Morikawa, S.; Kitagawa, H. Bull. Chem. Soc. Jpn. 2010, 83, 42–48. (c) Kawata, S.; Kitagawa, S.; Kumagai, H.; Ishiyama, T.; Honda, K.; Tobita, H.; Adachi, K.; Katada, M. Chem. Mater. 1998, 10, 3902–3912. (d) Kawata, S.; Kitagawa, S.; Kumagai, H.; Kudo, C.; Kamesaki, H.; Ishiyama, T.; Suzuki, R.; Kondo, M.; Katanda, M. Inorg. Chem. 1996, 35, 4449–4461. (e) Cueto, S.; Straumann, H.-P.; Rys, P.; Petter, W.; Gramlich, V.; Rys, F. S. Acta Crystallogr., Sect C: Cryst. Struct. Commun. 1992, 48, 458–460. (f) Kawata, S.; Kitagawa, S.; Kondo, M.; Katanda, M. Synth. Met. 1995, 71, 1917–1918. (g) Kawata, S.; Kitagawa, S.; Kondo, M.; Furuchi, I.; Munakata, M. Angew. Chem., Int. Ed. 1994, 33, 1759–1761. (3) Abrahams, B. F.; Lu, K. D.; Moubaraki, B.; Murray, K. S.; Robson, R. J. Chem. Soc., Dalton. Trans. 2000, 1793–1797. (4) (a) Zheng, L.-M.; Schmalle, H. W.; Huber, R.; Decurtins, S. Polyhedron 1996, 15, 4399–4405. (b) Papadimitriou, C.; Veltsistas, P.; Marek, J.; Novosad, J.; Slawin, A. M. Z.; Woolins, J. D. Inorg. Chem. Commun. 1998, 1, 418–420. (c) Decurtins, S.; Schmalle, H.; Zheng, L.-M.; Ensling, J. Inorg. Chim. Acta 1996, 244, 165–170. (d) Kabir, M. K.; Kawahara, M.; Kumagai, H.; Adachi, K.; Kawata, S.; Ishii, T.; Kitagawa, S. Polyhedron 2001, 20, 1417–1422. (5) Kumagai, H.; Kawata, S.; Kitagawa, S. Inorg. Chim. Acta 2002, 337, 387–392. (6) Robl, C.; Weiss, A. Mater. Res. Bull. 1987, 22, 497–504. (7) Abrahams, B. F.; Coleiro, J.; Ha, K.; Hoskins, B. F.; Orchard, S. D.; Robson, R. J. Chem. Soc., Dalton. Trans. 2002, 1586–1594. (8) Frenzer, W.; Wartchow, R.; Bode, H. Z. Kristallogr. 1997, 212, 237. (9) Nakabayashi, K.; Ohkoshi, S.-I. Inorg. Chem. 2009, 48, 8647–8649. (10) Robson, R. Comprehensive Supramolecular Chemistry; Lehn, J.-M., Ed.;Pergamon Press: U.K., Vol. 6, Chapter 22, pp 733 755. (11) Preparation of (NBu4)2[MII2(dhbq)3] 3 solvate (M = Mn, Fe Co, Ni, Zn, and Cd) from 2,5-diaminobenzoquinone. Suspensions of 2,5-diaminobenzoquinone (∼25 mg) and an equimolar amount of the metal acetate (or the sulfate in the case of FeII) together with an excess of NBu4Br (∼250 mg) in water (5 7 mL) were loaded into thick walled glass tubes, which were sealed off and heated at 115 °C for 1 2 days to yield crystalline products. Crystals large enough for structural determination by single crystal X-ray diffraction were obtained in all cases except for M = Cd, for which only unit cell data could be obtained. Anal. Calc for (NBu4)2[MnII2(dhbq)3]: C, 59.2; H, 8.3; N, 2.8%. Found: C, 59.1; H, 8.0; N, 2.9%. Calc for (NBu4)2[FeII2(dhbq)3] 3 H2O: C, 57.0; H, 8.4; N, 2.7%. Found: C, 57.2; H, 7.7; N, 2.7%. Calc for (NBu4)2[ZnII2(dhbq)3] 3 1.5H2O: C, 55.1; H, 8.3; N, 2.6%. Found: C, 55.1; H, 7.3; N, 2.6%. Calc for (NBu4)2[CdII2(dhbq)3]: C, 53.1; H, 7.5; N, 2.5%. Found: C, 53.1; H, 6.8; N, 2.6%. (NBu4)2[ZnII2(dhbq)3] 3 2MeOH from 1,2,4,5-tetrahydroxybenzene. A crystalline product identical to that prepared above from 2,5-diaminobenzoquinone was obtained by reaction of Zn(OAc)2 3 2H2O (21 mg, 0.096 mmol) in water (1 mL) with 1,2,4,5-tetrahydroxylbenzene (20 mg, 0.14 mmol) and NBu4Br (45 mg, 0.14 mmol) in methanol (6 mL). After several days, red hexagonal plate 2719

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crystals formed on the walls of the reaction vial: (NBu4)2[MnII2(can)3] 3 MeOH from 1,2,4,5-tetrahydroxy-3,6-dichlorobenzene. A saturated aqueous solution of Mn(NO3)2 (1 drop) was diluted in water (1 mL) and added to a solution of 3,6-dichloro-1,2,4,5-tetrahydroxybenzene (30 mg, 0.14 mmol) and NBu4Br (46 mg, 0.14 mmol) in methanol (1 mL). Upon addition of lithium acetate monohydrate (38 mg, 0.45 mmol) in methanol (1 mL), a deep purple color appeared at the solution surface and gradually diffused throughout the reaction mixture over a day. Brown rod crystals of (NBu4)2Mn2(can)3 3 MeOH (8 mg, 6.4 μmol, 14% yield) formed upon standing at room temperature for 2 days. Anal. Calc for (NBu4)2[MnII2(can)3] 3 MeOH: C, 49.1; H, 6.1; N, 2.3; Cl, 17.1%. Found: C, 48.8; H, 6.2; N, 2.3; Cl, 17.0%. (12) Crystal data and refinement details for the following: (a) (NBu4)2[Fe2(dhbq)3] 3 9H2O: C50H96Fe2N2O21, Mr 1172.99, cubic, Ia3d, a = 22.1408(10) Å, V = 10853.8(8) Å3, Z = 8, μ = 4.960 mm 1, T = 130(2) K, no. of measured (and independent) reflections 4098 (916), wR2 (all data) = 0.3104, R1 [I > 2σ(I)] = 0.0991. (b) (NBu4)2[Zn2(dhbq)3] 3 6H2O: C50H90N2O18Zn2, Mr 1137.98, cubic, Ia3d, a = 22.266(5) Å, V = 11039(4) Å3, Z = 8, μ = 1.663 mm 1, T = 130(2) K, no. of measured (and independent) reflections 4630 (982), wR2 (all data) = 0.2795, R1 [I > 2σ(I)] = 0.0978. (c) (NBu4)2[Ni2(dhbq)3] 3 4H2O: C50H86N2Ni2O16, Mr 1088.63, cubic, Ia3d, a = 22.1014(13) Å, V = 10795.9(11) Å3, Z = 8, μ = 1.429 mm 1, T = 130(2) K, no. of measured (and independent) reflections 2524 (498), wR2 (all data) = 0.4083, R1 [I > 2σ(I)] = 0.1048. (d) (NBu4)2[Co2(dhbq)3] 3 7H2O: C50H92Co2N2O19, Mr 1143.12, cubic, Ia3d, a = 22.2434(11) Å, V = 11005.3(9) Å3, Z = 8, μ = 5.341 mm 1, T = 130(2) K, no. of measured (and independent) reflections 3814 (909), wR2 (all data) = 0.3805, R1 [I > 2σ(I)] = 0.1250. (e) (NBu4)2[Mn2(dhbq)3] 3 13H2O: C50H104Mn2N2O25, 1243.23, tetragonal, I41/acd, a = 23.4246(6) Å, c = 21.3264(12) Å, V = 11702.0(8) Å3, Z = 8, μ = 4.219 mm 1, T = 130 (2) K, no. of measured (and independent) reflections 11635 (2892), wR2 (all data) = 0.3675, R1 [I > 2σ(I)] = 0.1252. (e) (NBu4)2[Cd2(dhbq)3]; a = 22.78(8) Å. (f) (NBu4)2[Mn2(can)3] 3 6MeOH: C58H104Cl6Mn2N2O20, Mr 1472.01, cubic, I43d, a = 22.7292(6) Å, V = 11742.3(5) Å3, Z = 8, μ = 6.700 mm 1, T = 130(2) K, no. of measured (and independent) reflections 2274 (962), wR2 (all data) = 0.2441, R1 [I > 2σ(I)] = 0.0954. (g) (NBu4)2[Zn2(dhbq)3] 3 2MeOH: C52H86N2O14Zn2, Mr 1093.97, cubic, Ia3d, a = 22.215(3) Å, V = 10963(3) Å3, Z = 8, μ = 1.599 mm 1, T = 130(2) K, no. of measured (and independent) reflections 2248 (501), wR2 (all data) = 0.2317, R1 [I > 2σ(I)] = 0.0873. Structures were solved and refined using SHELX9713 within the WinGX system of programs.14 Attempts to model the highly disordered cations and solvent molecules were unsuccessful, and as a result, the SQUEEZE routine within PLATON15 was employed. Details relating to the use of SQUEEZE are included in the Supporting Information. (13) Sheldrick, G. M. SHELX97—Programs for Crystal Structure Analysis, release 97-2; Institut fur Anorganische Chemie der Universitat Gottingen: Gottingen, Germany, 1998. (14) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837–838. (15) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool; Utrecht University: Utrecht, The Netherlands, 2005.

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