Two Isomers with FSC Topology Constructed from Cu6I6(DABCO)4

Oct 3, 2007 - Cite this:Crystal Growth & Design 7, 10, 2066-2070 ... Crystal Growth & Design 2018 18 (1), 22-26. Abstract | Full ... Coordination-Indu...
0 downloads 0 Views 379KB Size
Download PDF
Two Isomers with FSC Topology Constructed from Cu6I6(DABCO)4 and Cu8I8(DABCO)6 Building Blocks Minghui Bi, Guanghua Li, Jia Hua, Yunling Liu, Xiaomin Liu, Yawei Hu, Zhan Shi,* and Shouhua Feng

CRYSTAL GROWTH & DESIGN 2007 VOL. 7, NO. 10 2066-2070

State Key Laboratory of Inorganic Synthesis & PreparatiVe Chemistry, College of Chemistry, Jilin UniVersity, Changchun 130012, P. R. China ReceiVed January 24, 2007; ReVised Manuscript ReceiVed July 16, 2007

ABSTRACT: Two isomers of copper halides of the framework formula (CuI)7(DABCO)2.5 were prepared by solvothermal methods, and their structures were determined by single-crystal X-ray diffraction. Both of the structures contain two types of secondary building units, which are connected differently giving rise to two three-dimensional structures. These two structures both contain FSC topology, which is only predicted by O’Keeffe in theory, and is the first observation, to our knowledge, of FSC topology in coordination polymers. The formations of these structures show a good example of different connectivity between the building units that can form different structures. The compounds have been characterized by powder X-ray diffraction, elemental analysis, thermogravimetric analysis (TGA), and photoluminescence studies. Introduction In the past decades, synthetic coordination chemistry has undergone rapid development. Within this field, molecular architecture1 and metal-organic frameworks are two interesting areas that have been widely studied.2 The former focuses on the shape and size of discrete supramolecular architecture, while the latter concerns the dimension of inorganic-organic frameworks. These two areas differ mainly in the topologies adopted by the structures, either discrete or polymeric. For given building blocks, different arrangements can lead to the formation of a series of structures belonging to these two areas. The structural relationship between polymeric and discrete architectures has recently been described as supramolecular isomerism,3 which is a useful concept for understanding the synthetic processes involved in obtaining these two structural classes with desired topologies. The existence of supramolecular isomerism in metal-organic frameworks has received much attention, and different types have been reported.4 For example, Chen and coworkers reported structural isomerism of three supramolecular isomers of a one-dimensional zigzag chain and two discrete octagonal and decagonal molecular rings by the reactions of Cu(NO3)2 with 2-methylimidazolate in the presence of either methanol, toluene, or p-xylene template molecules.5 Champness et al. used topological isomerism to describe types of supramolecular isomers that are only different in topologies.6 Conformational isomerism, which plays an important role in supramolecular isomers, has also received much attention because the different conformations of a compound will affect its properties. However, the conformational isomerisms reported so far are all induced by the flexibility of ligands. For instance, MacGillivray and co-workers reported an unusual example of conformational isomerism that was built up by C-methylcalix[4]resorcinarene and 4,4′-bipyridine, in which C-methylcalix[4]resorcinarene was in different conformations: one in boat form and the other in bridge form.7 The conversion in the inorganic part of compounds has rarely been investigated. We have been interested in developing neutral metal-organic frameworks and decided to investigate metal-halide aggregation with rigid ligands, the reason being that the flexibility in * To whom correspondence should be addressed. E-mail: zshi@ mail.jlu.edu.cn. Phone: +86-431-85168317. Fax: +86-431-85168624.

semirigid or flexible ligands can lead to subtle or dramatic changes in architectures which may effect investigation on the inorganic part.8 Our previous investigation using dentate 2,2′bipyridyl resulted in some copper halides with novel inorganic clusters but low dimension.9 In contrast, bidentate rigid liner organic ligand can lead to high-dimension framework because of the nodes of the ligand at 180°. Therefore, we consider DABCO (DABCO ) 1,4-diazabicyclo[2.2.2]octane) as suitable ligand candidate to construct high-dimensional frameworks. In this paper we report an unusual case of isomers (CuI)7(DABCO)2.5, r and β, in which both isomers have the same stoichiometry, metal fragment, ligand-linker combinations, ligand conformations, and topology. Compounds r and β differ purely in the arrangement of unequivalent coordination nodes of one inorganic cluster, giving isomers of different symmetry. The thermal analysis of the two compounds reveals that there is no solvent in them. Experiment Section Materials. All reagents and solvents were commercially available and used as received without further purification. Physical Measurements. A Perkin-Elmer TGA 7 thermogravimetric analyzer was used to obtain thermogravimetric analysis (TGA) curves in air with a heating rate of 10 °C/min. Powder X-ray diffraction (XRD) data were collected on a Siemens D5005 diffractometer with Cu KR radiation (λ ) 1.5418 Å). Analyses for C, H, and N were carried out on a Perkin-Elmer analyzer. Synthesis of (CuI)7(DABCO)2.5 (r). Cu(CH3COO)2‚H2O (0.2 g, 0.1 mmol), HIO4‚2H2O (0.1 g, 0.44 mmol), NaClO4‚H2O (0.200 g, 1.42 mmol), NaHCO3 (0.100 g, 1.20 mmol), and C6H12N2‚6H2O (0.200 g, 0.91 mmol) were combined in the presence of ethanol (5.0 mL) under solvothermal conditions. The mixture was stirred in ethanol (5.0 mL) at room temperature for ca. 3 h to give a precipitate, and then this heterogeneous mixture was placed in a 15 mL Teflon-lined steel autoclave and heated to 160 °C for 72 h. The resulting yellow blocks were obtained by filtration, washed by distilled water, and air-dried (yield: 8% based on copper). Anal. Found: Cu, 27.79; I, 54.72; C, 11.08; N, 4.26; H, 2.05. Calcd: Cu, 27.85; I, 54.84; C, 11.12; N, 4.33; H, 1.84. Synthesis of (CuI)7(DABCO)2.5 (β). CuSO4‚5H2O (0.2 g, 0.07 mmol), HIO4‚2H2O (0.1 g, 0.44 mmol), NaClO4‚H2O (0.200 g, 1.42 mmol), NaHCO3 (0.100 g, 1.20 mmol), and C6H12N2‚6H2O (0.200 g, 0.91 mmol) were combined in the presence of ethanol (5.0 mL) under solvothermal conditions. The reaction conditions of β are the same as those of r. The resulting yellow blocks were obtained by filtration,

10.1021/cg0700824 CCC: $37.00 © 2007 American Chemical Society Published on Web 10/03/2007

Two Isomers with FSC Topology

Crystal Growth & Design, Vol. 7, No. 10, 2007 2067

Table 1. Crystal Data and Structural Refinement for r and β r

param empirical formula fw temp (K) wavelength (Å) cryst system space group unit cell dimens (Å, deg)

C15H30N5Cu7I7 1613.52 293(2) 0.710 73 monoclinc C2/m a ) 14.564(3) b ) 17.469(4) c ) 15.039(3) β ) 91.97(3)

V (Å3) Z calcd density (Mg/m3) abs coeff (mm-1) cryst size (mm3) reflcns collcd/unique data/restraints/params goodness-of-fit on F2 final R indices [I > 2σ(I)]a R indices (all data) a

3824.0(13) 4 2.803 9.483 0.32 × 0.28 × 0.24 18 969/4504 (Rint ) 0.0797) 4504/0/166 1.042 R1 ) 0.0529, wR2 ) 0.1321 R1 ) 0.0762, wR2 ) 0.1432

β C15H30N5Cu7I7 358.56 293(2) 0.710 73 triclinic P1h a ) 10.290(2) b ) 11.102(2) c ) 17.022(3) R ) 82.30(3) β ) 88.41(3) γ ) 69.13(3) 1800.2(6) 2 2.977 10.072 0.32 × 0.28 × 0.14 17650/8183 (Rint ) 0.0312) 8183/42/352 1.082 R1 ) 0.0359, wR2 ) 0.0767 R1 ) 0.0483, wR2 ) 0.0826

Figure 1. Experimental and simulated power X-ray diffractions of compounds r (black) and β (red).

R1 ) Σ||Fo| - |Fc||/Σ|Fo|. wR2 ) {Σ[w(Fo2 - Fc2)2]/Σ[w(Fo2)]2}1/2.

washed by distilled water, and air-dried (yield: 15% based on copper). Anal. Found: Cu, 27.73; I, 54.66; C, 11.23; N, 4.24; H, 2.13. Calcd: Cu, 27.85; I, 54.84; C, 11.12; N, 4.33; H, 1.84. X-ray Crystallographic Study. Single-crystal structure determination of r and β was carried out on Rigaku RAXIS-RAPID diffractometer equipped with graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å) at 293 K. The intensity data sets were collected with the w-scan technique and reduced by CrystalClear software. The structures were solved by direct methods and refined with the full-matrix leastsquares technique using the program SHELXTL. Anisotropic thermal parameters were assigned to all non-hydrogen atoms. The hydrogen atoms were set in calculated positions. The crystallographic data for r and β are listed in Table 1.

Results and Discussion Synthesis and Characterization. The pure phase of r can be synthesized in the Cu(CH3COO)2‚H2O, HIO4‚2H2O, NaClO4‚ H2O, NaHCO3, and C6H12N2‚6H2O reaction system. The type of anion from the copper source is important for the crystallization. When Cu(CH3COO)2‚H2O is changed to other copper salts such as CuCl2 or Cu(NO3)2, the product is the unknown phase in the form of brown ball-like powder. So the copper source can affect the final product of r but not that of β. On the other hand, the synthesis of β is significantly influenced by the ratio of water and ethanol, with the optimal ratio of 1:2. Less crystals of β can be obtained by increasing water and mixed crystals by increasing ethanol. It should be pointed out that the role of NaClO4‚H2O is very important because it can increase the oxidation ability of our system. The experimental and simulated X-ray powder diffraction patterns of r and β are in good agreement with each other, proving the phase purity of the as-synthesized products. The difference in reflection intensity is probably caused by the preferred orientation effect in the powder sample. The absence of some reflections might be due to their relatively low intensity (Figure 1). Crystal Structure of r and β. A single-crystal X-ray diffraction study performed on r and β revealed the formation of two extended 2-fold interpenetration three-dimensional coordination frameworks. The structures of r and β are both

Figure 2. Basic building blocks of r and β: (a) double six-membered ring Cu6I6 cluster in r and β; double-cubane Cu8I8 cluster in (b) r and (c) β. The arrows show the directions of the other linking clusters. Color code: orange ) Cu; green ) I.

constructed from the building blocks of Cu6I6(DABCO)4 and Cu8I8(DABCO)6. In r and β, the structure of the hexanuclear Cu6I6 cluster (Figure 2a), which is similar to the double six-membered (D6R, hexagonal prism) rings found in zeolite,10 is constructed by combination of two chair-shaped trinuclear Cu3I3 via six I anions. Until now only three compounds with hexanuclear Cu6X6 have been reported.9,11 In Cu6I6 cluster, there are two types of Cu+ cations. One type of Cu is coordinated to three iodide atoms with bond lengths in the range 2.577(3)-2.782(5) Å in a planar trigonal geometry. The other type of Cu atom, which is in distorted tetrahedral geometry, is coordinated to three

2068 Crystal Growth & Design, Vol. 7, No. 10, 2007

iodide atoms and a nitrogen atom from DABCO. The distances of Cu-I bonds are from 2.6368(16) to 2.7041(17) Å. The bond lengths of Cu-I bonds are in the normal range as reported before. And the Cu-N bond distance is about 2.109(8) Å, which is also within rational range.8,9 In the R and β isomers, every Cu6I6 cluster is linked to four Cu8I8 clusters through four DABCO molecules. The clusters of Cu8I8 (Figure 2b,c), which are different in r and β isomers, have two types of Cu+ cations. One type of Cu atom is coordinated to four iodide atoms with the Cu-I bond length in the range 2.577(3)-2.756(2) Å. The other type of Cu atom is coordinated to three iodide atoms and one nitrogen atom from DABCO. The bond lengths of Cu-I bonds are in the range 2.6644(13)-2.7277(16) Å, similar to those reported in CuxIx. The clusters of Cu8I8 may be seen as a double-cubane core conformed by two Cu4I4 clusters. The two Cu4I4 clusters are linked together through two Cu-I bonds. Several examples of double-cubane clusters have been reported in Fe-S and Mo-O clusters.12 As far as we know, the Cu8I8 cluster we reported here is the first example of double-cubane clusters in copper halides. In r and β isomers, every Cu8I8 cluster is linked to two other Cu8I8 clusters and four Cu6I6 clusters through six DABCO molecules. The Cu8I8 clusters, which make r and β isomers, are a little different in the two compounds. We can see clearly that the locations of nodes linking the two Cu8I8 clusters are different in r and β (Figure 2b,c). If we rotate the Cu8I8 cluster, in Figure 2b, 120°, the coordination nodes of the Cu8I8 clusters in r and β will be accordant. This case is similar to the conformation in ethane, in which each conformation can convert to other conformations by rotation in ethane. However, Cu8I8 is a rigid cluster with two parallel Cu-I bonds, which cannot rotate freely. This is different from T shape isomers in which the same clusters in different arrangements form different frameworks. In r and β, each Cu6I6(DABCO)4 or Cu8I8(DABCO)6 connects four Cu8I8(DABCO)6 or four Cu6I6(DABCO)4 units through four DABCO’s, forming a two-dimension sheet (Figure 3a,c). The other two coordinated nodes of each Cu8I8 join two Cu8I8 clusters, one of which is in one neighbor plane and the other is in another neighbor plane, through two DABCO organic ligands of one Cu8I8(DABCO)6 unit. In this way, Cu6I6(DABCO)4 and Cu8I8 (DABCO)6 form the frameworks of r and β. Two of these nets interlock each other to give rise to the three-dimentional framework of the compounds (Figure 3). The difference between two sheets in R and β can be seen clearly in Figure 3a,c. In R, the distances between Cu8I8 and Cu6I6 are equal with angle of Cu8I8-Cu6I6-Cu8I8 of 74°. In β, the distances between Cu8I8 and Cu6I6 are a little different with angle of Cu8I8-Cu6I6-Cu8I8 of 70°. This fine difference can be attributed to the difference in Cu8I8 clusters in the two compounds. A better insight into the nature of the involved framework can be achieved by the application of a topological approach through reducing multidimensional structures to simple nodeand-connection nets. As described above, each Cu6I6 core can be defined as a planar 4-connected node. Likewise, the Cu8I8 core bridging six clusters can act as a 6-connected node. On the basis of the simplification principle, the resulting structure of single infinite network in the two compounds is a (4,6)connected net.13 In this net, there exist four 4-membered and eight 6-membered circuits through each six-connected node. Four 4-membered and two 6-membered circuits are through each 4-connected node. Thus, the net can be characterized by the long Scha¨fli symbol 4.4.4.4.6(5).6(5).6(5).6(5).6(5).6(5).6(5).6(5).* *. *. for each six-connected node and 4.4.4.4.6(2).6(2)

Bi et al.

Figure 3. Connections in r and β: (a) the single framework in r; (b) the array of Cu6I6 and Cu8I8 in the ac plane in r; (c) the single framework in β; (d) the array of Cu6I6 and Cu8I8 in the ac plane in β. Color code: blue ) N; gray ) C; orange ) Cu; green ) I.

for each four-connection node, and the coordination sequences are 6,18,38,66,102,146,198,258,326,402 for 6-connected node and 4,16,38,66,102,146,198,258,326,402 for 4-conncted node, respectively, which have the same long Scha¨fli symbol and coordination sequence with FSC topology on the basis of 4-connected Cu6I6 and 6-connected Cu8I8.14 In addition, the two identical FSC nets are further interpenetrated in unprecedented 2-fold mode (Figure 4). Thermal Analysis. The TG curves of r and β measured in the temperature range 35-800 °C are shown in Figure 5. The two compounds are stable up to ca. 230 °C. In the range 230455 °C, the weight loss should correspond to the decomposition of DABCO ligands and the sublimation of iodine. Finally, the sample is converted to CuO, which is stable in air.

Two Isomers with FSC Topology

Crystal Growth & Design, Vol. 7, No. 10, 2007 2069

centered” excited state is supported by a Cu‚‚‚Cu nonbonding interaction. The photoluminescence property of the compounds and the mechanism are similar to those of Cu4I4L4 (L ) ligand) clusters.15 Conclusions

Figure 4. 2-Fold-interpenetrated net of r and β constructed from two identical FSC topologies.

Two isomers containing the same stoichiometry, metal fragment, ligand-linker combinations, ligand conformations, and topology have been successfully synthesized under solvothermal conditions. The anion has an important effect on the formation of R and β, and the solvent favors the formation of high-quality large single crystals of R and β. The structures of the two isomers are built up from the alternation of two clusters of Cu6I6 and Cu8I8, the former being a novel cluster in CuX and the latter a new double-cubane cluster in CuX system. Two isomers containing no solvent can be seen as an example of isomers in high-dimension compounds. The structures contain FSC topology, which is the first example of FSC in crystals. Acknowledgment. This work was supported by the National Natural Science Foundation of China (Grants No. 20121103, 20671040, and 20601010), the National High-tech R&D Program (863 program) of China, and the Fox Ying Tong Education Foundation. Supporting Information Available: X-ray crystallographic files in CIF format for r and β. This material is available free of charge via the Internet at http://pubs.acs.org.

References Figure 5. TGA curves of (a) r and (b) β.

Figure 6. (a) Solid-state emission spectra of r excited at 390 nm with emission at 588 nm. (b) Solid-state emission spectra of β excited at 390 nm with emission at 592 nm.

Photoluminescent Properties. It is interesting to note that the two compounds show the same photoluminescence at room temperature in the solid state. The intermixture displays a single excitation peak with maximum at 390 nm that leads to a broad yellow emission at 588 nm of r and 592 nm of β (Figure 6). The emissions observed in the intermixture cannot be assigned to MLCT (metal-to-ligand charge transfer) or LMCT (ligandto-metal charge transfer) in nature and can be attributed to a triplet “cluster-centered” (3CC*) excited state, which involves both the Cu cations and I ions and has mixed iodide-to-metal charge transfer (3XMCT*) and “metal cluster centered” (3MCC*, d10Cu f d9s1Cu) character. The existence of a “metal cluster

(1) (a) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2002, 100, 853. (b) Maverick, A. W.; Buckingham, S. C.; Yao, Q.; Bradbury, J. R.; Stanley, G. G. J. Am. Chem. Soc. 1986, 108, 7430. (c) Hartshorn, C. M.; Steel, P. J. Inorg. Chem. 1996, 35, 6902. (d) Swiegers, G. F.; Malefetse, T. J. Chem. ReV. 2000, 100, 3483. (e) Linton, B.; Hamilton, A. D. Chem. ReV. 1997, 97, 1669. (f) Chopra, D.; Thiruvenkatam, V.; Guru Row, T. N. Cryst. Growth Des. 2006, 6, 843. (g) Su, C. Y.; Goforth, A. M.; Smith, M. D.; zur Loye, H. C. Inorg. Chem. 2003, 42, 5685. (2) (a) Eddaoudi, M.; Moler, D. B.; Li, H.; Chen, B.; Reineke, T. M.; O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2001, 34, 319. (b) Cotton, F. A.; Lin, C.; Murillo, C. A. Chem. Commun. 2001, 11. (c) Hagrman, D.; Hagrman, P. J.; Zubieta, J. Angew. Chem., Int. Ed. 1999, 38, 3165. (d) Horike, S.; Matsuda, R.; Tanaka, D.; Mizuno, M.; Endo, K.; Kitagawa, S. J. Am. Chem. Soc. 2006, 128, 4222. (e) Vishweshwar, P.; Beauchamp, D. A.; Zaworotko, M. J. Cryst. Growth Des. 2006, 6, 2429. (f) Fang, Q. R.; Zhu, G. S.; Xue, M.; Sun, J. Y.; Wei, Y.; Qiu, S. L.; Xu, R. R. Angew. Chem., Int. Ed. 2005, 44, 3845. (g) Zeng, Y. F.; Liu, F. C.; Zhao, J. P.; Cai, S.; Bu, X. H.; Ribas, J. Chem. Commun. 2006, 2227. (h) Liu, Y.; Kravtsov, V. Ch.; Larsena, R.; Eddaoudi, M. Chem. Commun. 2006, 1488. (3) Moulton, B.; Zaworotko, M. J. Chem. ReV. 2001, 101, 1629. (4) (a) Fujita, M.; Kwon, Y. J.; Sasaki, O.; Yamaguchi, K.; Ogura, K. J. Am. Chem. Soc. 1995, 117, 7287. (b) Abourahma, H.; Moulton, B.; Kravtsov, V.; Zaworotko, M. J. J. Am. Chem. Soc. 2002, 124, 9990. (c) Dong, Y. B.; Smith, M. D.; Layland, R. C.; zur Loye, H. C. Chem. Mater. 2000, 12, 1156. (d) Masaoka, S.; Tanaka, D.; Nakanishi, Y.; Kitagawa, S. Angew. Chem., Int. Ed. 2004, 43, 2530. (e) Tong, M. L.; Hu, S.; Wang, J.; Kitagawa, S.; Ng, S. W. Cryst. Growth Des. 2005, 5, 837. (f) Novozhilova, I. V.; Coppens, P.; Lee, J.; RichterAddo, G. B.; Bagley, K. A. J. Am. Chem. Soc. 2006, 128, 2093. (g) Ragavan, A.; Khan, A. I.; O’ Hare, D. J. Mater. Chem. 2005, 16, 602. (h) Bowes, K. F.; Cole, J. M.; Husheer, S. L. G.; Raithby, P. R.; Savarese, T. L.; Sparkes, H. A.; Teat, S. J.; Warren, J. E. Chem. Commun. 2006, 2448. (i) Gong, Y.; Hu, C. W.; Li, H.; Huang, K. L.; Tang, W. J. Solid State Chem. 2005, 178, 3152. (5) Huang, X. C.; Zhang, J. P.; Chen, X. M. J. Am. Chem. Soc. 2004, 126, 13218. (6) Blake, A. J.; Brooks, N. R.; Champness, N. R.; Crew, M.; Deveson, A.; Fenske, D.; Gregory, D. H.; Hanton, L. R.; Hubberstey, P.; Schro¨der, M. Chem. Commun. 2001, 1432.

2070 Crystal Growth & Design, Vol. 7, No. 10, 2007 (7) (a) MacGillivray, L. R.; Diamente, P. R.; Reid, J. L.; Ripmeester, J. A. Chem. Commun. 2000, 359. (b) MacGillivray, L. R.; Spinney, H. A.; Reid, J. L.; Ripmeester, J. A. Chem. Commun. 2000, 517. (c) MacGillivray, L. R.; Reid, J. L.; Ripmeester, J. A. Chem. Commun. 2001, 1034. (8) (a) Hu, S.; Tong, M. L. Dalton Trans. 2005, 1165. (b) Lee, I. S.; Shin, D. M.; Chung, Y. K. Chem. Eur. J. 2004, 10, 3158. (c) Zhou, Y. F.; Jiang, F. L.; Yuan, D. Q.; Wu, B. L.; Wang, R. H.; Lin, Z. Z.; Hong, M. C. Angew. Chem,. Int. Ed. 2004, 43, 5665. (d) Zhang, Z. M.; Li, Y. G.; Wang, E. B.; Wang, X. L.; Qin, C.; An, H. Y. Inorg. Chem. 2006, 45, 4313. (e) Wang, X. L.; Qin, C.; Wang, E. B.; Su, Z. M.; Li, Y. G.; Xu, L. Angew. Chem., Int. Ed. 2006, 45, 7411. (9) Li, G. H.; Shi, Z.; Liu, X. M.; Dai, Z. M.; Feng, S. H. Inorg. Chem. 2004, 43, 6884. (10) Baerlocher, C.; Meier, W. M.; Olson, D. H. Atlas of Zeolite Structure Types, 5th ed.; Elsevier: London, 2001. (11) (a) Xue, X.; Wang, X. S.; Xiong, R. G.; You, X. Z.; Abrahams, B. F.; Che, C. M.; Ju, H. X. Angew. Chem., Int. Ed. 2002, 41, 2944. (b)

Bi et al.

(12)

(13)

(14) (15)

Adam, D.; Herrschaft, B.; Hartl, H. Z. Naturforsch., B 1991, 46, 738. (a) Hauser, C.; Bill, E.; Holm, R. H. Inorg. Chem. 2002, 41, 1615. (b) Koutmos, M.; Coucouvanis, D. Inorg. Chem. 2004, 43, 6508. (c) Zuo, J. L.; Zhou, H. C.; Holm, R. H. Inorg. Chem. 2003, 42, 4624. (d) Zhang, Y. G.; Holm, R. H. J. Am. Chem. Soc. 2003, 125, 3910. (e) Zhang, Y. G.; Zuo, J. L.; Zhou, H. C.; Holm, R. H. J. Am. Chem. Soc. 2002, 124, 14292. (a) Wells, A. F. Three-dimensional Nets and Polyhedra; Wiley: New York, 1977. (b) Wells, A. F. Further Studies of Three-dimensional Nets; American Crystallographic Association Monograph 8; American Crystallographic Association: Buffalo, NY, 1979. http://okeeffe-ws1.la.asu.edu/RCSR/home.htm. (a) Ford, P. C.; Vogler, A. Acc. Chem. Res. 1993, 26, 220. (b) Kyle, K. R.; Ryu, C. K.; DiBenedetto, J. A.; Ford, P. C. J. Am. Chem. Soc. 1991, 113, 2954. (c) Ford, P. C.; Cariati, E.; Bourassa, J. Chem. ReV. 1999, 99, 3625.

CG0700824