naphthalene: Syntheses, Crystal Structures, and Theoretical Inve

2-7 possess similar (4,4) 2-D sheet structures containing one type of quadrangle ... 8 also displays a (4,4) 2-D network structure but with two kinds ...
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CRYSTAL GROWTH & DESIGN

Metal Coordination Architectures of 1,4-Bis(imidazol-1-ylmethyl)naphthalene: Syntheses, Crystal Structures, and Theoretical Investigations on the Coordination Properties of the Ligand

2007 VOL. 7, NO. 2 286-295

Cai-Yun Li, Chun-Sen Liu, Jian-Rong Li, and Xian-He Bu* Department of Chemistry, Nankai UniVersity, Tianjin 300071, P. R. China ReceiVed June 14, 2006; ReVised Manuscript ReceiVed October 3, 2006

ABSTRACT: Eight new metal complexes of an imidazole-based ligand 1,4-bis(imidazol-1-ylmethyl)naphthalene (L), {[Ag(L)](ClO4)}∞ (1), {[Cd(L)2(H2O)2](NO3)2}∞ (2), {[Mn(L)2(H2O)2](Cl)2}∞ (3), {[Zn(L)2(H2O)2](NO3)2}∞ (4), {[Co(L)2(H2O)2](NO3)2}∞ (5), {[Co(L)2(H2O)(SO4)](H2O)2}∞ (6), {[Mn(L)2(SCN)2]}∞ (7), and {[Zn(L)(L1)](H2O)1.5}∞ (8, H2L1 ) fumaric acid), were synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction analyses. 1 has a square-wave-like one-dimensional (1-D) chain structure, which further assembled into a two-dimensional (2-D) layer through an interchain π‚‚‚π interaction. 2-7 possess similar (4,4) 2-D sheet structures containing one type of quadrangle grid, and the adjacent sheets are further interlinked by intersheet π‚‚‚π stacking interaction to form a three-dimensional (3-D) supramolecular network. 8 also displays a (4,4) 2-D network structure but with two kinds of different quadrangle grids, being different from that of 2-7. The structural differences of the eight complexes mainly depend on the geometrical requirement of the different metal ions and the influence of anions, as well as the presence of auxiliary ligand (in 8). Our research also demonstrates that intra- and/or intermolecular π‚‚‚π stacking play important roles in the formation of these coordination networks, especially in the aspect of linking the low-dimensional entities into high-dimensional supramolecular frameworks. Moreover, a brief analysis of the coordination properties of L has been carried out by density functional theory, combining experimental results. The construction of coordination architectures, based on the interactions of metal ions and organic ligands, has been rapidly developed because of their fascinating structural diversities and potential applications as functional materials, such as moleculebased magnets,1 optical materials,2 host-guest chemistry,3 electronic materials,4 catalytic materials,5 and so on. In this regard, a remarkable variety of polymers have been synthesized by assembling organic ligands bearing N-donors, such as pyridine-based ligands,6 benzimidazole-based ligands,7 and imidazole-based ligands8 and transition metal ions. The formation of coordination architectures mainly depends on the combination of the coordination geometry of metal ions and the nature of ligands.9 However, the methodologies to use transition metal ions as connecting nodes to hold together organic ligands in predefined patterns within self-assembled oligomeric or polymeric aggregates still remain a great challenge,10 and such studies still attract great attention.11 Also, besides coordination bonding,13 some weak interactions, such as H-bonding14 and π‚‚‚π15 interactions, often affect the structures of complexes, and they can further link discrete subunits or low-dimensional entities into high-dimensional supramolecular networks.9-12 Fan et al. has initially reported two phosphate complexes of 1,4-bis(imidazol-1-yl-methyl)-naphthalene (L).16a,18a To investigate the influences of the nature of ligand and/or anions on the formations of metal complexes of this ligand, we carried out the reaction of L and several transition metal salts with different anions under different reaction conditions. Eight new complexes, {[Ag(L)](ClO4)}∞ (1), {[Cd(L)2(H2O)2](NO3)2}∞ (2), {[Mn(L)2(H2O)2](Cl)2}∞ (3), {[Zn(L)2(H2O)2](NO3)2}∞ (4), {[Co(L)2(H2O)2](NO3)2}∞ (5), {[Co(L)2(H2O)(SO4)](H2O)2}∞ (6), ({[Mn(L)2(SCN)2]}∞ (7), and {[Zn(L)(L1)](H2O)1.5}∞ (8), (L1 ) fumarate) were obtained and structurally characterized. * To whom correspondence should be addressed. Fax: +86-2223502458. E-mail: [email protected].

Furthermore, to explore the relationship between the nature of L ligand and its coordination properties with metal ions, we analyzed the different conformations of L in these complexes and performed density functional theory (DFT) calculations on the energies of three selected conformations.

Experimental Section Materials and General Methods. All the solvents and reagents for synthesis were commercially available and used as received or prepared by reported procedures. 1,4-Bis-bromomethyl-naphthalene was synthesized by a literature method.17 Elemental analyses (C, H, N) were performed on a Perkin-Elmer 240C analyzer, and IR spectra were measured on a Tensor 27 OPUS (Bruker) FTIR spectrometer with KBr pellets. Thermal stability [thermogravimetric-differential thermal analysis (TG-DTA)] studies were carried out on a Dupont thermal analyzer from room temperature to 800 °C. The emission/excitation spectra were recorded on a JOBIN YVON (HORIBA) FLUOROMAX-P fluorescence spectrophotometer. Preparation of 1,4-Bis(imidazol-1-ylmethyl)naphthalene (L). The ligand 1,4-bis(imidazol-1-ylmethyl)naphthalene (L) was first synthesized by Zou et al.,18b but it can be more conveniently obtained by a slightly modified procedure for the preparation of 1,4-bis(imidazol-1ylmethyl)benzene.19 A solution containing imidazole (0.021 mol) and 1,4-bis-bromomethyl-naphthalene (0.002 mol) in methanol (17 mL) was heated under reflux for ca. 16 h. Then, anhydrous K2CO3 (2.74 g) was added, and the mixture was continuously stirred and refluxed for 2 h. After cooling, the mixture was filtered, and the filtrate was evaporated to dryness. An oily crude product was obtained, then dissolved in CHCl3, and washed with water for several times. The organic phase was separated, dried with anhydrous MgSO4, and evaporated to dryness

10.1021/cg0603570 CCC: $37.00 © 2007 American Chemical Society Published on Web 12/24/2006

1,4-Bis(imidazol-1-ylmethyl)naphthalene

Figure 1. View of (a) the coordination environment of Ag(I) ions in 1 with the intrachain C-H‚‚‚O H-bonding interactions; (b) the 2-D layer of 1 formed by the interchains π‚‚‚π stacking interactions (H atoms omitted for clarity); and (c) the 3-D network structure of 1 linked by C-H‚‚‚O H-bonds. with a rotary evaporator. The white product was obtained, which was further recrystallized from chloroform/hexane to give a white powder of 1,4-bis(imidazol-1-ylmethyl)naphthalene. Yield: ∼50%. Synthesis of Complexes 1-8. {[Ag(L)](ClO4)}∞ (1). A buffer solution (6 mL) of acetone and water (1:1) was carefully layered over an aqueous solution (3 mL) of AgClO4‚H2O (0.05 mmol). Then a solution (3 mL) of L (0.05 mmol) in acetone was layered over the buffer layer. Colorless crystals were obtained after ca. three weeks with a yield of ∼40%. Anal. Calcd for C18H16AgClN4O4: C 43.62, H 3.25, N 11.30; Found: C 43.12, H 3.45, N 11.13. IR (KBr, cm-1): 3131m, 1603w, 1518m, 1467w, 1388w, 1341w, 1301w, 1238s, 1099vs, 950s, 847s, 805w, 767m, 656m, 621m.

Crystal Growth & Design, Vol. 7, No. 2, 2007 287 The synthesis methods of 2-6 are similar to that of 1 except for Cd(NO3)2‚4H2O, MnCl2‚4H2O, Zn(NO3)2‚6H2O, Co(NO3)2‚6H2O, and CoSO4‚7H2O as the substitutes of AgClO4‚H2O, respectively. Among them, 2, 4, and 5 were also obtained under hydrothermal conditions as follows. {[Cd(L)2(H2O)2](NO3)2}∞ (2). A mixture of Cd(NO3)2‚4H2O (0.15 mmol), L (0.3 mmol), and H2O (10 mL) was sealed in a 25 mL stainless steel reactor with Teflon liner and directly heated to 180 °C for 2 days and then cooled to room temperature during 1 day. Colorless single crystals suitable for X-ray diffraction were obtained in ∼35% yield. Anal. Calcd for C36H36CdN10O8: C 50.92, H 4.27, N 16.49; Found: C 50.71, H 4.24, N 16.55. IR (KBr, cm-1): 3108m, 2361w, 2049vs, 1653w, 1618w, 1518s, 1441s, 1235m, 1109m, 1098m, 1081m, 932.8w, 880w, 832w, 781w, 763w, 657m, 622w. {[Mn(L)2(H2O)2](Cl)2}∞ (3). Yield: ∼40%. Anal. Calcd for C36H36MnCl2N8O2: C 58.54, H 4.91, N 15.17; Found C 58.24, H 4.98, N 14.87. IR (KBr, cm-1): 3119m, 3084m, 1649m, 1603w, 1520s, 1439m, 1383w, 1347w, 1287w, 1255w, 1232s, 1108s, 1084vs, 934s, 834s, 784s, 746s, 699m, 662s. {[Zn(L)2(H2O)2](NO3)2}∞ (4). Yield: ∼50%. Anal. Calcd for C36H36ZnN10O8: C 53.91, H 4.52, N 17.46; Found: C 53.44, H 4.50, N 17.64. IR (KBr, cm-1): 3116w, 1650w, 1602w, 1522m, 1406vs, 1384vs, 1320vs, 1290m, 1236m, 1109m, 1089vs, 1044w, 937m, 833w, 775m, 742m, 662s, 621w. {[Co(L)2(H2O)2](NO3)2}∞ (5). Yield: ∼30%. Anal. Calcd for C36H36CoN10O8: C 54.34, H 4.56, N 17.60; Found: C 54.39, H 4.33, N 17.74. IR (KBr, cm-1): 3116m, 2059w, 1663w, 1521s, 1406vs, 1384vs, 1320vs, 1290s, 1236s, 1109m, 1088vs, 1044w, 938m, 833m, 801m, 775m, 663s. {[Co(L)2(H2O)(SO4)](H2O)2}∞ (6). Yield: ∼40%. Anal. Calcd for C36H38CoN8O7S: C 55.03, H 4.84, N 14.26; Found: C 55.49, H 4.66, N 14.13. IR (KBr, cm-1): 3090w, 1600w, 1521m, 1441w, 1384w, 1350w, 1292w, 1237m, 1086s, 935m, 830m, 788m, 765m, 740m, 659m, 625m. {[Mn(L)2(SCN)2]}∞ (7). An aqueous mixture (10 mL) containing L (0.2 mmol), MnSO4‚H2O (0.2 mmol) and KSCN (0.4 mmol) were added into a Teflon-lined stainless steel vessel (25 mL), and the vessel was sealed and heated to 140 °C for 2 days and then cooled to room temperature during 8 h. Colorless single crystals suitable for X-ray diffraction were obtained in ∼30% yield. Anal. Calcd for C38H32MnN10S2: C 61.04, H 4.31, N 18.73; Found: C 61.47, H 4.37, N 18.45. IR (KBr, cm-1): 3113w, 2071vs, 1599w, 1513m, 1435w, 1282w, 1231m, 1105m, 1081s, 1032s, 931m, 832m, 788m, 763m, 658m. {[Zn(L)(L1)](H2O)1.5}∞ (8). An aqueous mixture (10 mL) containing fumaric acid (0.2 mmol) and enough ZnO powder was stirred and heated under reflux for 2 h. After the reaction was finished, the mixture was cooled and filtered. A portion of the filtrate was placed in the bottom of the tube, and then a buffer solution (6 mL) of methanol and water (1:1) was carefully added. Finally, a methanol solution (3 mL) containing L (0.05mmol) was layered above the buffer solution. Two months later, colorless single crystals suitable for X-ray diffraction were obtained in ca. 40% yield. Anal. Calcd for C22H21N4O5.50Zn: C 53.40, H 4.28, N 11.32; Found: C 53.14, H 4.11, N 11.52. IR (KBr, cm-1): 3128w, 1588vs, 1520m, 1438w, 1346s, 1292w, 1242w, 1109m, 1097m, 988w, 951w, 830w, 799w, 751m, 695m, 655m. X-ray Data Collection and Structure Determinations. X-ray single-crystal diffraction data for 1-8 were collected on a Bruker Smart 1000 CCD diffractometer at 293(2) K with Mo-KR radiation (λ ) 0.71073 Å) by ω scan mode. The program SAINT20 was used for integration of the diffraction profiles. Semiempirical absorption corrections were applied using SADABS program. All the structures were solved by direct methods using the SHELXS program of the SHELXTL package and refined by full-matrix least-squares methods with SHELXL.21 Metal atoms in each complex were located from the E-maps and other non-hydrogen atoms were located in successive difference Fourier syntheses and refined with anisotropic thermal parameters on F2. Hydrogen atoms of carbon were included in calculated positions and refined with fixed thermal parameters riding on their parent atoms. The hydrogen atoms of part of water were located from Fourier difference maps with suitable restraint, and part of those could not be located in the difference map. Crystallographic data and experimental details for structural analyses are summarized in Table 1. Selected bond lengths and angles for 1-8 are listed in Tables 2 and 4-8, respectively, and the H-bonding geometry of 1 are summarized in Table 3.

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Table 1. Crystallographic Data and Structure Refinement Summary for Complexes 1-8

formula formula weight crystal system space group T/K a/Å b/Å c/Å R/deg β/deg γ/deg V/Å3 Z D/g cm-3 µ/mm-1 F(000) reflns measured obsd reflns Ra/wRb

formula formula weight crystal system space group T/K a/Å b/Å c/Å R/deg β/deg γ/deg V/Å3 Z D/g cm-3 µ/mm-1 F(000) reflns measured obsd reflns Ra/wRb a

1

2

3

4

C18H16AgClN4O4 495.67 triclinic P1h 294(2) 9.1610(17) 10.100(2) 11.595(2) 68.680(3) 72.598(3) 78.865(3) 949.4(3) 2 1.734 1.235 496 5042 3491 0.0463/0.1279

C36H36CdN10O8 849.15 orthorhombic Pbcn 294(2) 14.1135(17) 15.6079(18) 16.4276(19) 90 90 90 3618.7(7) 4 1.559 0.671 1736 18004 3365 0.0475/0.1621

C36H36Cl2MnN8O2 738.57 orthorhombic Pbcn 294(2) 14.1119(4) 15.0528(5) 15.4885(5) 90 90 90 3290.12(18) 44 1.496 0.612 1532 17347 3853 0.0391/0.1083

C36H36ZnN10O8 802.12 orthorhombic Pbcn 294(2) 14.026(2) 15.486(3) 16.261(3) 90 90 90 3532.2(11)

5

6

7

8

C36H36CoN10O8 795.68 orthorhombic Pbcn 294(2) 14.0403(2) 15.5071(2) 16.1866(3) 90 90 90 3524.22(9) 4 1.500 0.556 1652 15587 3255 0.0350/0.1107

C36H38CoN8O7S 785.75 orthorhombic Pna2(1) 294(2) 16.0252(18) 16.1862(18) 13.4509(15) 90 90 90 3489.0(7) 4 1.496 0.615 1636 19021 7005 0.0408/0.0948

C38H32MnN10S2 747.80 orthorhombic Pbcn 294(2) 13.788(3) 15.602(4) 16.016(4) 90 90 90 3445.3(13) 4 1.442 0.550 1548 17328 3214 0.0462/0.1149

C22H21N4O5.50Zn 494.80 triclinic P1 294(2) 8.3073(13) 11.3775(19) 12.1610(19) 102.724(2) 106.377(2) 94.634(3) 1063.1(3) 2 1.546 1.201 510 6066 4290 0.0357/0.0954

R ) ∑(||F0| - |FC||)/∑|F0|. b wR ) [∑w(|F0|2 - |FC|2)2/∑w(F02)]1/2. Table 2. Selected Bond Distances (Å) and Angles (°) for Complex 1a

Ag(1)-N(2) N(2)#1-Ag(1)-N(2) a

1.508 0.765 1664 17616 3287 0587/0.1642

2.110(4) 180.0(2)

Ag(2)-N(3) N(3)#2-Ag(2)-N(3)

2.108(4) 180.0

Symmetry codes: #1 -x + 1, -y, -z; #2 -x + 1, -y - 1, -z + 1. Table 3. H-Bonding Geometry (Å, °) for 1a D-H‚‚‚A

D-H

H‚‚‚A

D‚‚‚A

D-H‚‚‚A

C(16)-H(16A)···O(4)i C(15)-H(15A)···O(4)ii C(15)-H(15B)···O(2)iii

0.930 0.970 0.970

2.43 2.51 2.54

3.2378 3.4359 3.4969

146 161 171

a Symmetry code: i: 1 - x, 1 - y, 1 - z; ii: -x, 1 - y, 1 - z; iii: x, -1 + y, z.

X-ray Powder Diffraction. The X-ray powder diffraction (XRPD) patterns of 1-8 were recorded on a Rigaku D/Max-2500 diffractometer, operated at 40 kV and 100 mA, using a Cu-target tube and a graphite monochromator. The intensity data were recorded by continuous scan in a 2θ/θ mode from 3 to 80° with a step size of 0.02° and a scan speed of 8° min-1. Simulation of the XRPD spectra was carried out by the single-crystal data and diffraction-crystal module of the commercially available Cerius2 program.22 Computational Details. We carried out ab initio molecular quantum mechanical methods at the B3LYP/6-31+G** level to conduct the optimizations. All zero-gradient conformations had been optimized using the eigenvector following algorithm, continued by a vibrational analysis to characterize the stationary points, and all the conformations

we had studied had no imaginary frequency. All calculations were carried out with the Gaussian03 program.23

Results and Discussion Complexes 1-6 and 8 were prepared at room temperature by diffusion methods, in which 2, 4, and 5 may also be prepared under hydrothermal conditions at 180 °C. However, 7 was synthesized under hydrothermal conditions at 140 °C. Meanwhile, the XRPD spectra data of 1-8 indicated that the pure phase of these complexes may always be obtained. Description of Crystal Structures. {[Ag(L)](ClO4)}∞ (1). 1 consists of the cationic square-wave-like24 1-D chains [Ag(L)]nn+ and ClO4- anions. As shown in Figure 1a, each Ag(I) ion locates at an inversion center and coordinated by two N donors from two distinct L ligands. Each L ligand in turn displays cis conformation to connect two Ag(I) ions to form an infinite 1-D chain. All the Ag-N bond distances range from 2.108(4) to 2.110(4) Å (Table 2), being a normal Ag-N coordination bond. The uncoordinated ClO4- anions serving as counter anions locate at the cavities of the chain and form C-H‚‚‚O and Ag‚‚‚O weak interactions with the cationic chain. The distances of H(16A)‚‚‚O(4) and Ag(1)‚‚‚O(2) are 2.426 and 3.236 Å, respectively, and the angle of C(16)-H(16A)‚‚‚O(4)i is 146° [symmetry code i: 1 - x, 1 - y, 1 - z; Table 3]. It is noteworthy that two naphthalene rings from adjacent layers are parallel to each other, and the centroid-centroid

1,4-Bis(imidazol-1-ylmethyl)naphthalene

Crystal Growth & Design, Vol. 7, No. 2, 2007 289

Figure 2. View of (a) the coordination environment of Cd(II), Zn(II), Co(II), and Mn(II) ions in 2-5, respectively; (b) (1) a (4,4) 2-D grid layer and (2) a smallest ring constructed by four L and four metal ions and intralayers π‚‚‚π stacking interactions exist in such ring; (c) the 3-D network of 2-4 formed through the interlayers and intralayers π·‚‚‚π stacking interactions between two adjacent layers, and (d) the 3-D network of 5 formed through the interlayers and inner layers π‚‚‚π stacking interactions between two adjacent layers (H atoms omitted for clarity).

separation is 3.756 Å and the dihedral angle is 0°, respectively. Therefore, such chains assemble by the π‚‚‚π interaction between the naphthalene rings to form an infinite 2-D supramolecular network (Figure 1b). Furthermore, in addition to the (π···π interaction, weak C-H‚‚‚O hydrogen-bonding interactions also play an important role in forming the supramolecular network (Figure 1c). The O atoms of the uncoordinated ClO4anions and the H atoms of methylene form C(15)-H(15A)‚‚‚

O(4)ii and C(15)-H(15B)‚‚‚O(2)iii H-bonds [symmetry code ii: -x, 1 - y, 1 - z; iii: x, -1 + y, z; see also Table 3]. These hydrogen bonds link the 2-D layers to a 3-D network; the related data are listed in Table 3. {[M(L)2(H2O)2](NO3)2}∞ M ) Cd (2), M ) Zn (4), M ) Co (5), and {[Mn(L)2(H2O)2](Cl)2}∞ (3). In contrast to the twocoordinated Ag(I) ions in 1, metal ions such as Cd(II), Mn(II), Zn(II), and Co(II) have a coordination number of 4-7.25 To

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Table 4. Selected Bond Lengths (Å) and Angles (°) for Complexes 2, 4, and 5a 2

4

5

M(1)-N(1) M(1)-N(4) M(1)-O(1W)

2.315(3) 2.325(3) 2.343(4)

2.138(4) 2.170(3) 2.168(4)

2.1460(17) 2.1541(18) 2.1336(17)

N(1)#1-M(1)-N(1) N(1)#1-M(1)-N(4) N(1)-M(1)-N(4) N(4)#1-M(1)-N(4) N(1)#1-M(1)-O(1W) N(1)-M(1)-O(1W) N(4)#1-M(1)-O(1W) N(4)-M(1)-O(1W) O(1W)-M(1)-O(1W)#1

180.00(11) 93.27(11) 86.73(11) 180.00(11) 93.48(13) 86.52(13) 92.64(13) 87.36(13) 179.99(13)

180.0 92.23(13) 87.77(13) 180.00(10) 92.62(16) 87.38(16) 92.36(16) 87.64(17) 180.00(14)

180 92.00(7) 88.00(7) 180 92.69(7) 87.31(7) 92.19(8) 87.81(8) 180

a

Symmetry codes: #1 -x, -y, -z + 1.

evaluate the role of metal ions with different geometrical requirements in crystal engineering of metal-organic complexes, the reactions of L with Cd(II), Mn(II), Zn(II), and Co(II) metal ions were carried out to afford complexes 2-5, respectively. Structural analyses were carried out, and similar cell parameters of them (Table 1) indicate that they are isomorphous and isostructural. Compounds 2, 4, and 5 have the general formula of {[M(L)2(H2O)2](NO3)2}∞. In 3, the coordination environment of Mn(II) ion is also the same as that of 2, 4, and 5, only with different counter anions located at the cavities of the interlayers. Therefore, we use M instead of Cd(II), Mn(II), Zn(II) and Co(II) to describe their structures later in this text. Figure 2a shows the coordination environments of the metal ion. Each metal ion resides at an inversion center and is sixcoordinated in a distorted octahedral environment. Two O atoms occupy the axial position with M-O(water) distances ranging from 2.1336(2) to 2.343(4) Å. The equatorial plane is defined by four N donors from four distinct L ligands with M-N(imidazolyl) distances ranging from 2.138(4) to 2.325(3) Å (Table 4). Each L in turn as a bridging ligand connects two metal ions to form a (4,4) 2-D grid layer in ab-plane [Figure 2b(1)]. All metal ions in each layer are completely coplanar. The M‚‚‚M separations are 10.521(1), 10.317(0), 10.447(1), and 10.459(0) Å for 2-5 with M(2)‚‚‚M(1)‚‚‚M(4) corner angles of 84.24°, 86.30°, 84.34°, and 84.32°, respectively. In each (4,4) grid, four L ligands connect four metal ions to form a 52-membered ring, and two naphthalene rings from two opposite L ligands are almost parallel to form the weak intralayer π‚‚‚π interaction [Figure 2b(2)]. The centroid-centroid separations are 3.953, 3.774, 3.890, and 3.884 Å for 2-5, respectively, and the dihedral angles are 0°. In addition, the uncoordinated anions (NO3- for 2, 4, 5, and Cl- for 3) are located in the voids between two 2-D layers to balance the charge. It is interesting that these 2-D layers are further extended into 3-D supramolecular networks by interlayer π‚‚‚π stacking interactions between the naphthyl rings from adjacent layers (Figure 2c). The centroid-centroid separations are 3.686, 3.524, 3.663, and 3.654 Å for 2-5 with dihedral angles of 2.0°, 0.7°, 3.0°, and 3.2°, respectively. In conclusion, with the decrease of the radii of the central metal ions Cd(II) (1.490 Å), Mn(II) (1.370 Å), Zn(II) (1.330 Å), and Co(II) (1.250 Å) in 2-5, the axial M-O(water) distances [2.343(4) for 2, 2.257(2) for 3, 2.167(5) for 4, and 2.134(2) Å for 5] and the equatorial M-N(imidazolyl) distances [2.325(3) and 2.315(3) Å for 2, 2.264(2) and 2.242(2) Å for 3, 2.138(3) and 2.170(3) Å for 4, 2.154(2) and 2.146(2) Å for 5] become shorter, and the M-O(water) distances become shorter faster than those of the equatorial M-N(imidazolyl). Further-

Figure 3. View of (a) the coordination environment of Co(II) ions in 6, (b) a (4,4) 2-D grid layer, and (c) the 3-D network of 6 formed by the interlayers and intralayers π‚‚‚π stacking interactions.

more, the centroid-centroid separations of the interlayer π‚‚‚π stacking interactions also become shorter from 2 to 5. Besides the radii of metal ions, the counter anions also play an important role in the strength of such π‚‚‚π stacking interactions. The radius of Mn(II) in 3 is larger than that of Zn(II) in 4; generally, the intralayer and interlayer centroid-centroid separation in 3 should be larger than that of 4, respectively. However, the smaller volume of chloride ions in 3 lead to shorter intralayer

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Crystal Growth & Design, Vol. 7, No. 2, 2007 291

Table 5. Selected Bond Lengths (Å) and Angles (°) for Complex 3a

a

Mn(1)-N(1)#1 Mn(1)-O(1W) Mn(1)-N(4)#2

2.2420(16) 2.2571(15) 2.2637(15)

Mn(1)-N(4)#3 N(4)-Mn(1)#4

2.2637(15) 2.2637(15)

N(1)#1-Mn(1)-N(1) N(1)#1-Mn(1)-O(1W) N(1)-Mn(1)-O(1W) O(1W)-Mn(1)-O(1W)#1 N(1)#1-Mn(1)-N(4)#2 N(1)-Mn(1)-N(4)#2 O(1W)-Mn(1)-N(4)#2

180.00(8) 91.93(6) 88.07(6) 180.0 92.24(6) 87.76(6) 90.83(6)

O(1W)#1-Mn(1)-N(4)#2 N(1)#1-Mn(1)-N(4)#3 N(1)-Mn(1)-N(4)#3 O(1W)-Mn(1)-N(4)#3 O(1W)#1-Mn(1)-N(4)#3 N(4)#2-Mn(1)-N(4)#3

89.17(6) 87.76(6) 92.24(6) 89.17(6) 90.83(6) 180.0

Symmetry codes: #1 -x, -y, -z + 1; #2 -x + 1/2, y - 1/2, z; #3 x - 1/2, -y + 1/2, -z + 1; #4 x + 1/2, -y + 1/2, -z + 1.

Table 6. Selected Bond Lengths (Å) and Angles (°) for Complex 6 Co(1)-O(1) Co(1)-N(7) Co(1)-N(1)

2.089(2) 2.094(3) 2.106(3)

Co(1)-N(3) Co(1)-N(5) Co(1)-O(1W)

2.161(3) 2.165(3) 2.200(3)

O(1)-Co(1)-N(7) O(1)-Co(1)-N(1) N(7)-Co(1)-N(1) O(1)-Co(1)-N(3) N(7)-Co(1)-N(3) N(1)-Co(1)-N(3) O(1)-Co(1)-N(5) N(7)-Co(1)-N(5)

87.46(12) 94.15(12) 177.56(13) 89.02(11) 86.28(12) 91.91(12) 92.01(11) 95.85(12)

N(1)-Co(1)-N(5) N(3)-Co(1)-N(5) O(1)-Co(1)-O(1W) N(7)-Co(1)-O(1W) N(1)-Co(1)-O(1W) N(3)-Co(1)-O(1W) N(5)-Co(1)-O(1W)

85.94(11) 177.67(14) 175.37(13) 87.90(12) 90.48(12) 90.60(11) 88.53(11)

Table 7. Selected Bond Lengths (Å) and Angles (°) for Complex 7a Mn(1)-N(4) Mn(1)-N(5)

2.246(3) 2.249(3)

Mn(1)-N(2)

2.268(2)

N(4)-Mn(1)-N(4)#1 N(4)-Mn(1)-N(5)#1 N(4)-Mn(1)-N(5) N(5)#1-Mn(1)-N(5) N(4)-Mn(1)-N(2)#1

180.00(14) 89.99(11) 90.01(11) 180.0 94.69(9)

N(4)-Mn(1)-N(2) N(5)#1-Mn(1)-N(2) N(5)-Mn(1)-N(2) N(2)#1-Mn(1)-N(2)

85.31(9) 92.61(10) 87.39(10) 180.00(8)

a

Symmetry code: #1 -x, -y, -z + 1.

Table 8. Selected Bond Lengths (Å) and Angles (°) for Complex 8 Zn(1)-O(2) Zn(1)-O(3)

1.9578(18) 1.9744(18)

Zn(1)-N(4) Zn(1)-N(2)

2.006(2) 2.028(2)

O(2)-Zn(1)-O(3) O(2)-Zn(1)-N(4) O(3)-Zn(1)-N(4)

104.11(8) 115.49(9) 117.09(9)

O(2)-Zn(1)-N(2) O(3)-Zn(1)-N(2) N(4)-Zn(1)-N(2)

116.72(8) 97.47(8) 105.02(9)

(3.774 Å) and interlayer (3.524 Å) centroid-centroid separations than those of 4. {[Co(L)2(H2O)(SO4)](H2O)2}∞ (6). To investigate the influence of counter anions in constructing coordination frameworks, 6 was obtained by the reaction of L with CoSO4‚7H2O instead of Co(NO3)2‚6H2O used for 5. As shown in Figure 3a, 6 has a similar structure to 5 and consists of a 2-D neutral coordination network with the coordination geometry around Co(II) ion being similar to that in 5, replaced by one sulfate ion instead of one water molecule coordination in 5. All coordinated bonds are also within the normal range26,27 (Table 6). For the π‚‚‚π stacking interactions, the centroid-centroid separations of intralayer and interlayer π‚‚‚π stacking interactions in 6 are 3.621 and 3.597 Å, and the dihedral angles are 4.7° and 3.0°, respectively. Obviously, in comparison with 5, the distances of intralayer and interlayer π‚‚‚π stacking interactions in 6 are much shorter. Such a change may be attributed to the weak electrostatic repulsion between layers in 6. {[Mn(L)2(SCN)2]}∞ (7). Complex 7 also displays (4,4) 2-D grid layer structure, but the introduction of NCS- ions leads to some differences in the metal coordination environment. Each Mn(II) ion resides in a N6 binding set, with four N donors from

Figure 4. View of (a) the coordination environment of Mn(II) ions in 7, (b) the 3-D supramolecular network of 7 formed by π‚‚‚π stacking interactions between 2-D layers (H atoms omitted for clarity).

four distinct L ligands in the equatorial plane, and two NCSions instead of two water molecules of 3 at the axial positions (Figure 4a). The Mn-N(NCS-) distances [2.249(3) Å] and MnN(imidazolyl) distances [2.246(3) and 2.268(2) Å] are all within the normal range,28,29 and N(imidazolyl)-Mn-N(NCS-) angles range from 85.31(9) to 94.69(9)° (Table 7). In comparison with

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Li et al.

Figure 5. View of (a) the coordination environment of Zn(II) ions in 8, (b) the (4,4) 2-D planar network with two different types of channel, (c) top view showing the packing of the grid layers in 8, and (d) topological view of 8 and Zn(II) ions are taken as nodes, and L ligands are substituted by white sticks and fumaric acids by purple sticks.

3, the different coordination environment of metal ions in 7 also leads to different strengths of intralayer and interlayer π‚‚‚π stacking interactions. The intra- and interlayer centroidcentroid separations for 7 are 3.788 and 3.597 Å, and the dihedral angles are 0.0° and 0.5°, respectively (Figure 4b). {[Zn(L)(L1)](H2O)1.5}∞ (8). 8 also has a 2-D structure, but the local coordination geometry around the Zn(II) ion is a distorted tetrahedron with N2O2 donor set (Figure 5a). Two N donors from two different L ligands coordinate to Zn(II) ions with the Zn(1)-N(4) and Zn(1)-N(2) bond distance of 2.006(2) and 2.028(2) Å, respectively. The N(4)-Zn(1)-N(2) bond angle is 105.02(9)°. The other two positions are occupied by two O atoms from two different fumarate ligands with the

Zn(1)-O(2) and Zn(1)-O(3) bond distance of 1.9578(2) and 1.9744(2) Å, respectively. The O(2)-Zn(1)-O(3) bond angle is 104.11(8)°, and O-Zn-N bond angles range from 97.47(8) to 117.09(9)° (Table 8). Each L ligand and fumarate in turn bridge two Zn(II) ions. The salient structural feature of compound 8 is that each L possesses trans conformation linking two Zn(II) ions. The bridged Zn‚‚‚Zn distance along µ-L is 11.377(2) Å, and two different Zn‚‚‚Zn distances along µ-fumarate are 8.813(2) and 8.888(1) Å, which are longer than the Mn‚‚‚Mn distances (linked by fumarate) in the complex {[Mn(fumarate)(µ-4,4′-bipy)-(H2O)]‚0.5(4,4′-bipy)}∞.30 Four Zn(II) ions, two L ligands, and two fumarates form a 40-membered ring (Figure 5b). Such linkages lead to the formation of a wave-

1,4-Bis(imidazol-1-ylmethyl)naphthalene

Crystal Growth & Design, Vol. 7, No. 2, 2007 293

Figure 7. Emission spectra of 1, 2, 4, and 8 as well as the free ligand L in the solid state at room temperature (λex ) 383 nm for L, 381 nm for 1, 378 nm for 2, 374 nm for 4, and 379 nm for 8).

Figure 6. (a) Theoretical view of cis and trans conformations of L and (b) actual conformations of L in 1, 2, and 8.

like (4,4) 2-D network structure with the grids having the dimensions of 11.377(2) × 8.888(1) and 11.377(2) × 8.813(2) Å2, respectively. Interestingly, there is no obvious intralayer or interlayer π‚‚‚π stacking interactions in 8, but the grid layers are closely stacking in an offset way with the cavity of each layer being occupied by the groups from the adjacent ones16b (Figure 5c). The 2-D network is further represented in a schematic representation for clarity in Figure 5d. It should be noted that, in comparison with 1-7, no π‚‚‚π stacking interactions are observed in the structure of 8, and meanwhile the bivalent metal ion Zn(II) in 8 is four-coordinated, which suggests that weak π‚‚‚π stacking interactions play an important role in the crystal structure of this system. It is also clear that owing to the existence of such weak interactions, the 2-D layer structure is linked into 3-D network, and the crystal structures are stabilized. Analysis of the Coordination Ability of L. In recent years, much attention has been paid to the importance of different conformations of flexible ligands in metal compounds;16b,31 however, to our knowledge, less attention has been paid to the influences of weak π‚‚‚π stacking interactions on ligand conformations in the crystal structures of metal complexes. In this regard, we performed some analyses on this aspect. As shown in Figure 6a, the conformational flexibility of L mainly arises from the relative rotation of the two imidazole rings about the line (denoted Csp3‚‚‚Csp3) connecting the two methylene carbon atoms (Csp3), which may be represented by the NCsp3‚‚‚Csp3-N torsion angle.16b In theory, this motion makes the conformation highly flexible and variable and finally affects the conformations and leads to intricate crystal structures. On the basis of the N-Csp3‚‚‚Csp3-N torsion angle, all conformations could be divided into cis (N-Csp3‚‚‚Csp3-N < 90°) and trans (N-Csp3‚‚‚Csp3-N > 90°). The N-Csp3‚‚‚Csp3-N torsion angles of L in 1-8 are 6.6°, 81°, 83°, 85°, 95°, 104°, 81°, and

154°, respectively. Thus, L has cis conformation in 1 and trans conformation in 8 but sits on the fence between cis and trans conformation in 2-7. According to the structural analysis of 1-8, we found that 1-7 all have interlayer π‚‚‚π stacking interactions between two parallel naphthyl rings from two adjacent layers, and some have intralayer π‚‚‚π stacking interactions, whereas 8 has neither interlayer nor intralayer π‚‚‚π stacking interactions. This result suggests that cis-L and the transitional conformation-L are more propitious to the formation of π‚‚‚π stacking interactions than trans-L. Therefore, L is apt to assume cis and transitional conformations rather than trans in coordination frameworks. This may be explained as the formation of interlayer and intralayer π‚‚‚π stacking interactions can lower the energy of the whole system and stabilize the crystal structure, to some extent. To make the question clear, we also did some DFT theoretical calculations on the energies of the three selected conformations of L (that in 1, 2, and 8). From the energies of these conformations, we found that cis-L in 1 is the most stable, followed by trans-L in 8, and then transitional conformation-L in 2 last. The energy of each transitional conformation-L in 2 is 4.5 kJ mol-1 higher than that of cis-L in 1, and 2 kJ mol-1 higher than that of trans-L in 8. This result again suggests that it is the π‚‚‚π stacking interactions that lower the energy of the whole system and stabilize the crystal structure and make the high-energy transitional conformations popular with M(II) ions. In other words, the interlayer and intralayer π‚‚‚π stacking interactions limit the conformations of L in cis or transitional ones in forming coordination complexes unless other strong interactions change them. As a result, a main crystal structural mode is formed. XRPD Results. To confirm whether the analyzed crystal structures are truly representative of the bulk materials, XRPD experiments were carried out for complexes 1-8. The XRPD experimental and computer-simulated patterns of the corresponding complexes are shown in Figure S1 of Supporting Information. Although the experimental patterns have a few unindexed diffraction lines and some are slightly broadened in comparison with those simulated from the single-crystal modes, it still can be considered that the bulk synthesized materials and the as-grown crystals for 1-8 are homogeneous. Thermogravimetric Analysis. TGA of complexes 1-8 was performed by heating the corresponding complexes from 20 to

294 Crystal Growth & Design, Vol. 7, No. 2, 2007

800 °C under N2. The TGA results of 1 and 7 showed that these two complexes decomposed upon 300 °C, which indicates that they have high thermal stability. Complexes 2, 4, and 5 lose two coordinated water molecules below 262 °C, and the corresponding weight losses were 4.62% (calcd. 4.24%) below 257 °C for 2, 4.91% (calcd. 4.49%) below 161 °C for 4, and 5.34% (calcd. 4.52%) below 262 °C for 5, respectively. Complex 6 loses one coordinated and two noncoordinated water molecules below 162 °C with the first weight loss of 7.32% (calcd. 6.87%). The TGA curve for complex 3 showed that the first major weight loss of the 10.12% (calcd. 9.61%) occurred between 128 and 190 °C (peaking at 183 °C), which corresponds to two noncoordinated Cl- anions. The decomposition of the residue started around 300 °C (peaking at 350 °C). The TGA curve for complex 8 showed that the first major weight loss of 5.76% (calcd. 5.46%) occurred between 100 and 158 °C (peaking at 156 °C), which corresponds to 1.5H2O. The second weight loss of 23.81% (calcd. 23.04%) occurred between 306 and 424 °C (peaking at 336 °C), which corresponds to loss of the L1 ligand. The rest gradually decomposed at higher temperatures (see Figure S2 in Supporting Information). Luminescent Properties. The luminescent properties of complexes 1, 2, 4, and 8 as well as free L ligand were investigated in the solid state at room temperature. As indicated in Figure 7, the emission spectra of the free ligand L and its complexes 1, 2, 4, and 8 exhibit strong blue emission. The emission maxima (λmax) are 406 (L), 429 (1), 427 (2), 430 (4), and 424 nm (8) (λex ) 383 nm for L, 381 nm for 1, 378 nm for 2, 374 nm for 4, and 379 nm for 8), respectively (see also Figure S3 in Supporting Information). Compared with the case of the free ligand L, 1, 2, 4, and 8 in the solid state all have a similar red shift. In light of previous studies, this red shift may be caused by a ligand-to-metal charge-transfer (LMCT) transition.32 The emission spectra of complexes 2 and 4 both show a broad emission. In comparison with 2 and 4, however, complex 1 has nearly overlapped dual emissions, which may also be caused by the different coordination environment of the metal ions. Complex 8 has interesting dual emissions, which may be attributed to the different structural topology of 8.33 These complexes might be potential materials for blue-light emitting diode devices and also be candidates for thermally stable and solvent-resistant blue fluorescent material.34 Conclusion Eight coordination polymers with 1,4-bis(imidazol-1-ylmethyl)naphthalene have been synthesized and structurally analyzed. Their coordination architectures have a systematic structural variation by the employment of different metal ions and counter-anions. The result shows that the structures of such complexes could be adjusted by geometrical requirement of the metal ions and/or counter anions (or auxiliary ligands). More importantly, in this system π‚‚‚π stacking interactions have an important influence in linking the low-dimensional entities into high-dimensional supramolecular network and limiting the flexibility of the ligand. Complexes 1, 2, 4, and 8 as well as the free ligand L all display blue emissions at room temperature. Acknowledgment. This work was financially supported by the National Science Funds for Distinguished Young Scholars of China (No. 20225101) and NSFC (Nos. 20373028 and 20531040). Supporting Information Available: Crystallographic information files (CIF) of eight complexes, XRPD patterns of the 1-8 (Figure S1),

Li et al. thermogravimetric analysis of the complexes 1-8 (Figure S2), the excitation/emission spectra of free ligand L and the complexes 1, 2, 4, and 8 (Figure S3) are available free of charge via the Internet at http:// pubs.acs.org.

References (1) For example: Li, X. J.; Wang, X. Y.; Gao, S.; Cao, R. Inorg. Chem. 2006, 45, 1508. (2) For example: Niu, Y.; Song, Y.; Hou, H.; Zhu, Y. Inorg. Chem. 2005, 44, 2553. (3) For example: Dapporto, P.; Formica, M.; Fusi, V.; Micheloni, M.; Paoli, P.; Pontellini, R.; Romani, P.; Rossi, P. Inorg. Chem. 2000, 39, 2156. (4) For examples: (a) Bordiga, S.; Lamberti, C.; Ricchiardi, G.; Regli, L.; Bonino, F.; Damin, A.; Lillerud, K.-P.; Bjorgen, M.; Zecchina, A. Chem. Commun. 2004, 2300. (b) Shi, J. M.; Xu, W.; Liu, Q. Y.; Liu, F. L.; Huang, Z. L.; Lei, H.; Yu, W. T.; Fang, Q. Chem. Commun. 2002, 756. (5) For example: Legros, J.; Bolm, C. Chem. Eur. J. 2005, 11, 1086. (6) For examples: (a) Fujita, M.; Sasaki, O.; Watanabe, K.-Y.; Ogura, K.; Yamaguchi, K. New J. Chem., 1998, 189. (b) Ghumaan, S.; Sarkar, B.; Patra, S.; Parimal, K.; Slageren, J. V.; Fiedler, J.; Kaim, W.; Lahiri, G. K. Dalton Trans. 2005, 706. (7) For examples: (a) Li, L. K.; Song, Y. L.; Hou, H. W.; Fan, Y. T.; Zhu, Y. Eur. J. Inorg. Chem. 2005, 3238. (b) Ma, J. F.; Liu, J. F.; Liu, Y. C.; Xing, Y.; Jia, H. Q.; Lin, Y. H. New J. Chem. 2000, 24, 759. (8) For examples: (a) Wang, X. Y.; Li, B. L.; Zhu, X.; Gao, S. Eur. J. Inorg. Chem. 2005, 3277. (b) Li, F. F.; Ma, J. F.; Song, S. Y.; Yang, J. Cryst. Growth Des. 2006, 6, 209. (c) Ma, J. F.; Yang, J.; Zheng, G. L.; Li, L.; Liu, J. F. Inorg. Chem. 2003, 42, 7531. (d) Yang, J.; Ma, J. F.; Liu, Y. Y.; Li, S. L.; Zheng, G. L. Eur. J. Inorg. Chem. 2005, 2174. (9) For examples: (a) Sun, W. Y.; Kusukawa, T.; Fujita, M. J. Am. Chem. Soc. 2002, 124, 11570. (b) Schneider, R.; Hosseini, M. W.; Planeix, J. -M.; Cian, A. D.; Fischer, J. Chem. Commun. 1998, 1625. (c) Hall, J. S.; Loeb, J. G.; Shimizu, K. H.; Yap, G. P. A. Angew. Chem., Int. Ed. 1998, 37, 121. (d) Schnebeck, R. -D.; Freisinger, E.; Lippert, B. Angew. Chem., Int. Ed. 1999, 38, 168. (10) For examples: (a) Fujita, M. ComprehensiVe Supramol. Chem., Pergamon Press: Oxford, 1996, 9, 253. (b) Sun, W. Y.; Fan, J.; Okamura, T.; Xie, J.; Yu, K. B.; Ueyama, N. Chem. Eur. J. 2001, 7, 2557. (c) Chifotides, H. T.; Catalan, K. V.; Dunbar, K. R. Inorg. Chem. 2003, 42, 8739. (d) Berlinguette, C. P.; Galan-Mascaros, J. R.; Dunbar, K. R. Inorg. Chem. 2003, 42, 3416. (e) Fiedler, D.; Pagliero, D.; Brumaghim, J. L.; Bergman, R. G.; Raymond, K. N. Inorg. Chem. 2004, 43, 846. (11) For examples: (a) Zaworotko, M. J. Angew. Chem., Int. Ed. 2000, 39, 3052. (b) Melcer, N. J.; Enright, G. D.; Ripmeester, J. A.; Shimizu, G. K. H. Inorg. Chem. 2001, 40, 4641. (c) Liu, S. X.; Lin, S.; Lin, B. Z.; Lin, C. C.; Huang, J. Q. Angew. Chem., Int. Ed. 2001, 40, 1084. (12) For examples: (a) Huang, X. C.; Zhang, J. P.; Lin, Y. Y.; Yu, X. L.; Chen, X. M. Chem. Commun. 2004, 1100. (b) Cao, R.; Sun, D. F.; Liang, Y. C.; Hong, M. C.; Tatsumi, K.; Shi, Q. Inorg. Chem. 2002, 41, 2087. (c) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Porta, F. Angew. Chem., Int. Ed. 2003, 42, 317. (d) Oh, M.; Carpenter, G. B.; Sweigart, D. A. Angew. Chem., Int. Ed. 2003, 42, 2026. (e) Tong, M. L.; Wu, Y. M.; Ru, J.; Chen, X. M.; Chang, H. C.; Kitagawa,S. Inorg. Chem. 2002, 41, 4846. (f) Wu, C. D.; Lu, C. Z.; Lin, X.; Wu, D. M.; Lu, S. F.; Zhuang, H. H.; Huang, J. S. Chem. Commun. 2003, 1284. (g) Sekiya, R.; Nishikiori, S. Chem. Eur. J. 2002, 8, 4803. (h) Bu, X. H.; Tong, M. L.; Chang, H. C.; Kitagawa, S.; Batten, S. R. Angew. Chem., Int. Ed. 2004, 43, 192. (13) For examples: (a) Ockwig, N. W.; Delgado-Friedrichs, O.; O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2005, 38, 176. (b) Rosi, N. L.; Kim, J.; Eddaoudi, M.; Chen, B.; O’Keeffe, M.; Yaghi, O. M. J. Am. Chem. Soc. 2005, 127, 1504. (c) Yaghi, O. M.; Li, G.; Li, H. Nature 1995, 378, 703. (d) Yaghi, O. M.; Li, H. J. Am. Chem. Soc. 1995, 117, 10401. (e) Yaghi, O. M.; Li, H.; Groy, T. L. J. Am. Chem. Soc. 1996, 118, 9096. (f) Fujita, M.; Oka, H.; Yamaguchi, K.; Ogura, K. Nature 1995, 378, 469. (g) Losier, P.; Zaworotko, M. J. Angew. Chem., Int. Ed., Engl. 1996, 35, 2779. (h) Power, K. N.; Hennigar, T. L.; Zaworotko, M. J. Chem. Commun. 1998, 595.

1,4-Bis(imidazol-1-ylmethyl)naphthalene (14) For examples: (a) Alekseyeva, E. S.; Batsanov, A. S.; Boyd, L. A.; Fox, M. A.; Hibbert, T. G.; Howard, J. A. K.; MacBride, J. A. H.; Mackinnon, A.; Wade, K. J. Chem. Soc., Dalton Trans. 2003, 475. (b) Juan, C. M. R.; Lee, B. Coord. Chem. ReV. 1999, 183, 43. (c) Guru, Row: T. N. Coord. Chem. ReV. 1999, 183, 81. (d) Desiraju, G. R. Acc. Chem. Res. 1996, 29, 441. (15) For examples: (a) Kuduva, S. S.; Craig, D. C.; Nangia, A.; Desiraju, G. R. J. Am. Chem. Soc. 1999, 121, 1936. (b) Khlobystov, A. N.; Blake, A. J.; Champness, N. R.; Lemenovskki, D. A.; Majouga, A. G.; Zyk, N. V.; Schro¨der, M. Coord. Chem. ReV. 2001, 222, 155. (c) Unamuno, I.; Gutie´rrez-Zorrilla, J. M.; Luque, A.; Roma´n, P.; Lezama, L.; Calvo, R.; Rojo, T. Inorg. Chem. 1998, 37, 6452. (d) Tse, M. C.; Cheung, K. K.; Chan, M. C. W.; Che, C. M. Chem. Commun. 1998, 2295. (16) (a) Fan, J.; Yee, G. T.; Wang, G.; Hanson, B. E. Inorg. Chem. 2006, 45, 599. (b) Gao, E. Q.; Xu, Y. X.; Yan, C. H. CrystEngComm 2004, 6, 298. (17) G. Lock and R. Schneider, Chem. Ber. 1958, 91, 1770. (18) (a) Fan, J.; Hanson, B. E. Inorg. Chem. 2005, 44, 6998. (b) Zou, R. Y.; Xu, F. B.; Li, Q. S.; Zhang, Z. Z. Acta Crystallogr. 2003, E59, o1451. (19) Hoskins, B. F.; Robson, R.; Slizys, D. J. Am. Chem. Soc. 1997, 119, 2952. (20) SAINT Software Reference Manual; Bruker AXS: Madison, WI, 1998. (21) Sheldrick, G. M. SHELXTL NT, Version 5.1. Program for Solution and Refinement of Crystal Structures: University of Go¨ttingen, Germany, 1997. (22) Cerius2; Molecular Simulations Incorporated: San Diego, CA, 2001. (23) Gaussian 03, Revision C.01, Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.; Jr., Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.;

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(24) (25) (26) (27) (28) (29) (30) (31)

(32) (33) (34)

Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P. J.; Dannenberg, J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J .V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; and Pople, J. A.; Gaussian, Inc., Wallingford CT 2004. Fan, J.; Sun, W. Y.; Okamura, T.-A.; Zheng, Y. Q.; Sui, B.; Tang, W. X.; Ueyama, N. Cryst. Growth Des. 2004, 4, 579. Fan, J.; Sun, W. Y.; Okamura, T.-A.; Tang, W. X.; Ueyama, N. Inorg. Chem. 2003, 42, 3168. Zhou, Z. H.; Deng, Y. F.; Wan, H. L. Cryst. Growth Des. 2005, 5, 1109. Henson, N. J.; Hay, P. J.; Redondo, A. Inorg. Chem. 1999, 38, 1618. Liu, X. H.; Krott, M.; Mu1ller, P.; Hu, C. H.; Lueken, H.; Dronskowski, R. Inorg. Chem. 2005, 44, 3001. Lal, T. K.; Mukherjee, R. Inorg. Chem. 1998, 37, 2373. Shi, Z.; Zhang, L. R.; Gao, S.; Yang, G. Y.; Hua, J.; Gao, L.; Feng, S. H. Inorg. Chem. 2000, 39, 1990. For example: (a) Sui, B.; Zhao, W.; Ma, G. H.; Okamura, T. A.; Fan, J.; Li, Y. Z.; Tang, S. H.; J. Mater. Chem. 2004, 14, 1631. (b) Tan, H. Y.; Zhang, H. X.; Ou, H. D.; Kang, B. S. Inorg. Chim. Acta 2004, 357, 869. (c) Zhao, W.; Fan, J.; Okamura, T. a.; Sun, W. Y.; Ueyama, N. J. Solid State Chem. 2004, 177, 2358. Wei, K. J.; Xie, Y. S.; Ni, J.; Zhang, M.; Liu, Q. L. Cryst. Growth Des. 2006, 6, 1341. Wang, Y.; Yi, L.; Yang, X.; Ding, B.; Cheng, P.; Liao, D. Z.; Yan, S. P. Inorg. Chem. 2006, 45, 5822. Zou, R. Q.; Bu, X. H.; Zhang, R. H. Inorg. Chem. 2004, 43, 5382.

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