Influence of Anion and Mole Ratio on the Coordination Behavior of an

Feb 22, 2016 - Department of Chemistry and Research Institute of Natural Science, Gyeongsang ... ABSTRACT: Anion and mole ratio dependent formations o...
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Influence of Anion and Mole Ratio on the Coordination Behavior of an NO2S3‑Macrocycle: The Formation of a Dumbbell-Shaped Macrocyclic Cadmium(II) Iodide Complex Hyeong-Hwan Lee, Eunji Lee, Huiyeong Ju, Seulgi Kim, In-Hyeok Park,* and Shim Sung Lee* Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, South Korea S Supporting Information *

ABSTRACT: Anion and mole ratio dependent formations of cadmium(II) complexes with an NO2S3-macrocycle (L) incorporating a pyridine subunit are reported. When the cadmium(II) salts (1−10 equiv) with different halide ions (Br− or I−) were reacted with L, CdBr2 afforded a monomer complex, [Cd(L)Br]2[Cd2Br6]·CH2Cl2 (1), with three separated parts in the whole mole ratio range: two 1:1 stoichiometric complex cation parts and one Cd2Br6 cluster anion part. After separation of 1 by filtration, [Cd(L)Br]2[CdBr4]·CH2Cl2 (2) with similar composition was afforded, except the cluster was isolated from the filtrate. Unlike the CdBr2 complexation, CdI2 afforded the mole ratio dependent products (3−5). Below 2.5 equiv of CdI2, [Cd(L)I]2[CdI4]·CH2Cl2 (3) and [Cd(L)I]2[Cd2I6]·0.5CH2Cl2 (4) with different cadmium(II) iodide clusters were isolated as kinetic (3) and a thermodynamic (4) products. Notably, the use of 3 equiv or above amount of CdI2 gave a dumbbell-shaped complex, {[Cd(L)]2(μ-Cd4I12)} (5), in which two mononuclear macrocyclic complex units are linked by a (μ-Cd4I12)4− cluster. To monitor the mole ratio dependency as well as their reactivities, the systematic powder X-ray diffraction (PXRD) analysis has also been applied.

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INTRODUCTION Over the past four decades, much effort has been given to the preparation of new macrocyclic complexes with supramolecular topologies, involving not only typical endocyclic complexes but also their extended analogues with discrete and continuous forms related to the fascinating complementary structures and applicable properties as nanomaterials.1 Among the macrocyclic ligands, sulfur-bearing analogues, so-called thiamacrocycles, have a tendency to show a trans conformation due to a repulsive interaction between adjacent sulfur donors,2 and this conformation tends to lead to formation of continuous exocyclic networks3,4 in which the metal ions exist outside the macrocyclic cavity. Furthermore, the exocoordination can be adopted as a versatile tool for crystal engineering.4 Due to this reason, the exocyclic networks of soft metal ions with bridging coordinative anions have been our interest.4 In the course of our ongoing studies on the thiamacrocycles, we have also been interested in the extended coordinative species with the discrete forms such as sandwich,3c,5 clubsandwich,3c,6 double decker,7 cyclic oligomer,3b,8 and dumbbell.3a,9 Among them, to the best of our knowledge, few examples on the macrocyclic dumbbells linked with spacer coligands have been reported by us9 and other groups.10 For example, we have tried to interconnect two macrocyclic silver(I) complexes of thiaoxamacrocycles (L′) with spacer coligands (L″: 1,4-diazabicyclo[2,2,2]octane (dabco), 4,4bipyridine (bpy), or 1,4-bis(4-pyridyl)piperazine (bpp)) to obtain dumbbell-shaped complexes with an [(L′Ag)-L″(AgL′)] arrangement (Chart 1a).9a Grant et al. have also reported a dumbbell-shaped diruthenium(II) complex, [{Ru© XXXX American Chemical Society

(12S4)Cl}2(μ-bpy)] (12S4 = 1,4,7,10-tetrathiacyclododecane) linked with bpy.10a Chart 1. Dumbbell-Shaped Macrocyclic Complexes Linked with (a) Coligands, (b) [Hg2Br6]2− Cluster, and (c) Structure of L Used in This Work

Recently, as shown in Chart 1b, we have reported the first cluster-linked dumbbell-shaped complex [(LHg)-(μ-Hg2Br6)(HgL)] via one-pot reaction of HgBr2 with an NO2S3macrocycle L (Chart 1c).11 Motivated by these results, we assumed that some other soft metal halides might have the possibility to form dumbbell-shaped complexes with different stoichiometries or sizes. Thus, in this work, we have coupled the mole ratio approach with employing cadmium(II) bromide Received: January 5, 2016

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DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX

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obtained by slow evaporation for 1 day. The product 1 was separated by filtration. Interestingly, slow evaporation of the filtrate afforded a colorless block type crystalline product 2. When we allowed standing of the reaction mixture without filtration, after 2 weeks, we confirmed that the product obtained was compound 1 by PXRD data (Scheme 1). The SC-XRD analysis revealed that 1 is an anion-coordinated product having three-separated units with the formula [Cd(L)Br]2[Cd2Br6]·CH2Cl2: two macrocyclic complex cation units and one rhomboidal hexabromo dicadmium(II) cluster [Cd2Br6]2− anion unit (Figure 1a). The asymmetric unit

and iodide as guests and bridging cluster sources for the preparation of the dumbbell-shaped polynuclear bis(ligand) complex of L. We here report the five cadmium(II) halide complexes (1− 5) isolated depending on the mole ratio as well as anions (Br− and I−) (Scheme 1). On increasing the mole ratio of CdBr2, the Scheme 1. Cadmium(II) Halides Complexes of L

complexation shows no mole ratio dependency, but two solubility dependent mononuclear bromo species (1 and 2) were isolated, while CdI2 afforded three mole ratio dependent products (3−5). In the lower mole ratio of CdI2, for example, a kinetic (3) and a thermodynamic (4) controlled iodo complexes were isolated, while, in the higher mole ratio (>3 equiv), a unique dumbbell-shaped complex 5 linked with a (μCd4I12)4− cluster was isolated. To our knowledge, this is a first example of this type of cadmium(II) iodide cluster and the longest example of the dumbbell-shaped macrocyclic complexes (Chart 1b).11 The structural characteristics of the products with the different stoichiometries and coordination modes have been probed by single crystal X-ray diffraction (SC-XRD) analysis. Powder X-ray diffraction (PXRD) analysis has also been employed to monitor the mole ratio dependent products.

Figure 1. Crystal structure of 1, [Cd(L)Br]2[Cd2Br6]·CH2Cl2: (a) view of the three-separated parts and (b) the distorted pentagonal bipyramidal geometry of the Cd(II) center in the macrocyclic cation unit [∠Br1−Cd1−S2 167.94(9)°]. Noncoordinating solvent molecule was omitted. Symmetry unit of A: −x+0.5, −y+1.5, −z+1.

contains one macrocyclic complex cation and half of the cluster anion. In 1, the cation unit [Cd(L)Br]+ is a typical endocyclic mononuclear macrocyclic complex, in which a cadmium(II) center is accommodated inside the macrocyclic cavity. The cadmium(II) center is seven-coordinate, being bound to all six donors from L, adopting a twisted and partially folded conformation, due to a larger cavity size of L (20-memberd ring) for the cadmium(II) ion. The remaining coordination site is occupied by one Br atom [Cd1−Br1 2.5882(13) Å]. The coordination geometry of 1 can be described as a distorted pentagonal bipyramid with NO2S2-macrocyclic donors from L defining the pentagonal plane due to the ring strain of the macrocyclic skeleton (Figure 1b). And the axial sites are occupied by one remaining sulfur donor (S2) in the middle of the −S1−S2−S3− segment and one Br atom (Br1) with the Br1−Cd1−S2 axis angle 167.94(9)°. As expected, the pyridine nitrogen binds strongly to the metal center [Cd1−N1 2.395(12) Å], contributing to the endocyclic coordination. The Cd−S bond lengths [2.711(3)−2.838(4) Å] are typical.12 The distance of one Cd−O bond [Cd1−O2 2.624(7) Å] is also normal, but the other [Cd1−O1 2.870(12)] shows somewhat elongated length.

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RESULTS AND DISCUSSION L was prepared as described previously by us.11 In an attempt to examine the dependency of the mole ratio (CdX2/L: 1−10 equiv) on the coordination modes and stoichiometries of the complexes formed with L, a comparative study of the complexation of L with cadmium(II) bromide and iodide has been carried out. In the case of the chloride, no suitable solid product was isolated under the conditions employed. Cadmium(II) Bromide Complexes (1 and 2). The reactions of cadmium(II) bromide with L showed no mole ratio dependency. Instead, CdBr2 afforded two individual products (1 and 2) depending on the separation process (Scheme 1). For example, a colorless needle type product 1 was B

DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX

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10. Unlike the no product for the chloride system and no mole ratio dependency for the bromide system, interestingly, three products have been isolated for cadmium(II) iodide. When the mole ratios were in the range 1−2.5, two products were isolated: a kinetic (3) and a thermodynamic (4) controlled product. However, when the mole ratio increased above 3, a unique dumbbell-shaped product (5) was isolated, as depicted in Scheme 1. As a preliminary condition, when 2 equiv of cadmium(II) iodide was used in the reaction with L in dichloromethane/ acetonitrile, slow evaporation of the solution over 3 h at room temperature afforded a small number of brick type colorless crystals of 3. One single crystal from this batch was selected, and its SC-XRD analysis revealed that 3 shows three-separated parts (except the lattice solvent) with the formula [Cd(L)I]2[CdI4]·CH2Cl2, being similar to that in 2 (Figure 3a). Two

After complex 1 was separated from the mother liquid, as shown in the reaction pathways (Scheme 1), slow evaporation of the filtrate afforded the block type crystalline product 2. The SC-XRD analysis revealed that 2 also has three-separated units with the formula [Cd(L)Br]2[CdBr4]·CH2Cl2: two endocyclic cadmium(II) complex cation units and one tetrabromo monocadmium(II) cluster [CdBr4]2− anion unit (Figure 2a).

Figure 2. Crystal structure of 2, [Cd(L)Br]2[CdBr4]·CH2Cl2: (a) view of the three-separated parts in 2 and (b) the distorted pentagonal bipyramidal geometry of the Cd(II) center in the macrocyclic cation unit [∠Br1−Cd1−S2 164.24(3)° and ∠Br2−Cd2−S5° 168.56(3)°]. Noncoordinating solvent molecule was omitted.

The difference between 1 and 2 is the anion cluster unit with types [CdnBr2n+2]2−:[Cd2Br6]2− (n = 2) for 1 and [CdBr4]2− (n = 1) for 2. Unlike 1, the asymmetric unit of 2 contains all threeseparated units due to the less symmetric structure. The two crystallographically independent mononuclear macrocyclic complex units show somewhat different ligand conformations but their coordination spheres adopting the distorted pentagonal bipyramidal geometry are not significantly different and also similar to that in 1 (Figure 2b). As mentioned, complexes 1 and 2 have been isolated consecutively from the same flask before and after the filtration process. And the bulk purities of both species are confirmed by comparison of the PXRD patterns with the simulated ones based on the SC-XRD analysis (Figures S1 and S2). Furthermore, the straight reaction without the filtration only afforded compound 1 as a pure form (Scheme 1). So, the observed fractional crystallization that resulted in the successful separation of two species is mainly due to the less soluble property of 1 than 2. Cadmium(II) Iodide Complexes (3−5). We also performed a series of experiments in the preparation of CdI2 complexes with L by varying the mole ratio of CdI2/L from 1 to

Figure 3. Crystal structure of 3, [Cd(L)I]2[CdI4]·CH2Cl2: (a) view of the three-separated parts in 3 and (b) the distorted pentagonal bipyramidal geometry of the two Cd(II) centers in the macrocyclic cation units [∠I1−Cd1−S2 169.77(4)° and ∠I2−Cd2−S5 162.55(3)°]. Noncoordinating solvent molecule was omitted.

crystallographically independent macrocyclic complex units show similar coordination environment, adopting a distorted pentagonal bipyramidal geometry (Figure 3b). Attempts to isolate the brick type crystalline product 3 in higher yield were not successful. Interestingly, we found that the brick type product 3 transformed to the needle type crystalline product (4) of the formula [Cd(L)I]2[Cd2I6]·0.5CH2Cl2, when the reaction solution containing 3 was left undisturbed for 3 days (Figure 4); at the end of this period, only needle type crystals of 4 were present, and these had formed in substantially higher yield (70%) than occurred initially for crystalline 3. Similar to 1, the X-ray structure of 4 shows the three-separated units, and the C

DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX

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Figure 4. Crystal structure of 4, [Cd(L)I]2[Cd2I6]·0.5CH2Cl2: (a) view of the three-separated parts in 4 and (b) the distorted pentagonal bipyramidal geometry of the Cd(II) center in the macrocyclic cation unit [∠I1−Cd1−S2 167.61(15)°]. Noncoordinating solvent molecule was omitted. Symmetry unit of A: −x+1.5, −y+0.5, −z+1.

Figure 5. Crystal structure of 5, {[Cd(L)]2(μ-Cd4I12)}: (a) view of the dumbbell type bis(macrocycle) structure with a Cd1···Cd1A distance of 18.31 Å and (b) the distorted pentagonal bipyramidal geometry of the Cd(II) center in the macrocyclic cation unit [∠I1−Cd1−S2 165.79(7)°]. Symmetry units of A: −x+2, −y+1, −z+1; B: −x+1, −y +1, −z+2.

seven-coordinate cadmium(II) center features a distorted pentagonal bipyramidal geometry (Figure 4b). The observed conversion of 3 to 4 in the reaction solution on standing is in accord with the precursor complex 3 being a kinetic product, with the product 4 being a thermodynamic product. Comparison of the PXRD patterns for the synthesized 4 with the simulated data for 3 and 4 confirmed the phase purity of 4 (Figure S3); the purity of 3 was also confirmed by elemental analysis (see Experimental Section). Under the same reaction conditions but at 50 °C, as depicted in Scheme 1, only the needle-shaped crystals of 4 were obtained, suggesting the direct formation of the thermodynamic controlled product. When above 3 equiv of CdI2 was used in the reaction with L, a colorless crystalline product 5 was isolated. Crystal 5 features a dumbbell-shaped complex with the formula {[Cd(L)]2(μCd4I12)} in which two macrocyclic monocadmium(II) units are linked by a (μ-Cd4I12) 4− cluster via a Cd2−I1 bond [2.8291(14) Å] (Figure 5a). Since the inversion center locates at the center of the product molecule, the asymmetric unit contains half of the product. Once again, the endocyclic cadmium(II) center (Cd1) is seven-coordinate, being bound to all six donors from L, and the remaining coordination site is occupied by one I atom [Cd1−I1 2.8748(12) Å], adopting a distorted pentagonal bipyramidal geometry (Figure 5b). In 5, the length between the two metal centers (Cd1···Cd1A distance) in the macrocyclic cavities is 18.31 Å, which corresponds to ten consecutive Cd−I bonds [2.7145(13)− 2.9037(12) Å] in a zigzag form. Several dumbbell-type bis(macrocycle) complexes linked with organic and inorganic parts (bars) have been reported by us9,11 and other groups.10 As we understand it, this is the longest bis(macrocycle) dumbbell complex reported so far. The preferred dumbbell structure linked with the longest cluster is mainly due to the relatively higher coordination ability of I− than Br− toward the cadmium(II) ion as a soft base, which allows formation of the

longer zigzag cluster (μ-Cd4I12)4− to link two macrocyclic units via the Cd−I bonds. Systematic PXRD Studies. In order to monitor the mole ratio effect on the formations of cadmium(II) iodide complexes of L systemically, a series of the PXRD experiments were performed in the preparation of the complexes by varying the mole ratio from 1 to 10. The PXRD patterns of the products obtained in each mole ratio were collected and compared with the simulated PXRD patterns of 4 and 5 (Figure 6). When the mole ratios are in the range of 1.0−2.7, the PXRD patterns of the products (denoted with red color) are coincident with the simulated pattern of 4, indicating that 4 is an only product in this range. When the mole ratio reaches 2.8−2.9, some new peaks (denoted with blue reciprocal triangles) are observed, which corresponds to 5, indicating a mixture of 4 and 5 was formed. In the mole ratio above 3 (to 10), the evidence of 4 disappears and only 5 exists. The observed sudden conversion of the product in the mole ratio range 2.7−3.0 could be associated with the stabilization of the cluster aggregation and the repulsive interaction between two macrocyclic complex units because of the steric hindrance. From these results, it is concluded that the dumbbell-shaped product isolated in this work can be considered as an optimized one with the proper cluster length which shows the reduced steric hindrance. Indeed, nothing longer than the (μ-Cd4I12)4− cluster has been observed or detected both in this work and in the literature. Reactivities and Reversibility of the Complexes. The reversibility between 4 and 5 was examined by analyzing the isolated products for the forward and the reverse reactions in solution (Figure 7). When 4 was reacted with 2 equiv of CdI2 in acetonitrile/dichloromethane, it is found that 4 is not reactive (Figure 7A-b). Oppositely, when 5 was reacted with 2 equiv of L in the same condition, we confirmed that 4 was obtained as a colorless precipitate (Figure 7A-c), suggesting the D

DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX

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reactive. These phenomena might be explained by the theory that to induce the formation of the dumbbell structure 5 from the three-separated species 4, the entropic penalty is too high to undergo further complexation.

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CONCLUSION In summary, five cadmium(II) halide (Br− and I−) complexes of the NO2S3-macrocycle (L) have been prepared and structurally characterized. The results demonstrate that CdBr2 shows no mole ratio dependency and afforded two similar mononuclear bromo-complexes via the fractional crystallization due to the solubility difference. Unlike the bromo-complexes isolated, CdI2 afforded the mole ratio dependent three products, including a dumbbell-shaped complex linked with the (μ-Cd4I12)4− cluster. The systematic PXRD results for the CdI2 complexation support the observed dependency of the mole ratio as a controlling factor on the stoichiometries and coordination topologies of the resulting products. It is also found the the dumbbell-shaped one is reactive with the excess of L to go back to the three-separated species, including mononuclear species, but no reverse reaction occurs. Hence, the combined approach of the SC-XRD and the PXRD analysis has enabled in-depth information on the stoichiometries and topologies of the products, including the optimized condition for the formation of the dumbbell species. Further investigations on the cluster-linked dumbbell systems based on the macrocyclic complex and their potential applications are currently in progress.

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Figure 6. PXRD patterns of the products by varying the mole ratio of the reactants. The data shown in the bottom (4) and the top (5) represent the simulated PXRD patterns.

EXPERIMENTAL SECTION

General. All chemicals and solvents used in the syntheses were of reagent grade and were used without further purification. FT-IR spectra were measured with a ThermoFisher Scientific Nicolet iS 10 FT-IR spectrometer. The elemental analysis was carried out on a ThermoFisher Scientific Flash 2000 elemental analyzer. Mass spectra were obtained using a JEOL JMS-700 spectrometer (FAB) and a Thermo Scientific LCQ Fleet spectrometer (ESI). The NO2S3macrocycle L was prepared as described previously by us.11

irreversible conversion between 4 and 5 in the presence of the corresponding reactants as shown in Figure 7B. From the observed reactivity and the irreversibility, it is found that the three-separated complex 4 is not reactive, but the dumbbell complex 5, which involves a longer (μ-Cd4I12)4− linker, is

Figure 7. (A) PXRD patterns for (a) 4; (b) no reaction monitored from the reaction of 4 and 2.0 equiv of CdI2; (c) the solid product (identified as 4) obtained from the reaction of 5 with 2.0 equiv of L; and (d) 5. (B) The irreversible process between 4 and 5 in the presence of the corresponding reactants. All the reactions were carried out in methanol/dichloromethane. E

DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry Table 1. Crystallographic Data and Structure Refinement for 1−5 formula formula weight temperature crystal system space group Z a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Dcalc (g/cm3) 2θmax (deg) R1, wR2 [I > 2σ(I)] R1, wR2 [all data] goodness-of-fit on F2 no. of reflection used [>2σ(I)]

1

2

3

4

5

C51H56Br8Cd4Cl2N2O4S6 2113.12 173(2) Monoclinic C2/c 4 35.5113(11) 12.8092(4) 14.9514(4) 90 97.508(2) 90 6742.7(3) 2.082 52 0.0518, 0.1213 0.0968, 0.1616 1.089 6616 [Rint = 0.0605]

C102H112Br12Cd6Cl4N4O8S12 3681.80 173(2) Monoclinic P21/c 2 16.3685(2) 13.6176(2) 28.0662(4) 90 95.4100(10) 90 6228.08(15) 1.963 52 0.0339, 0.0757 0.0510, 0.0828 1.025 12248 [Rint = 0.0662]

C51H56Cd3Cl2I6N2O4S6 2122.84 173(2) Monoclinic P21/c 4 16.7160(4) 14.0128(3) 28.7392(7) 90 93.1720(10) 90 6721.5(3) 2.098 52 0.0329, 0.0787 0.0442, 0.0858 0.938 13212 [Rint = 0.0638]

C51H58Cd4Cl2I8N2O4S6 2491.05 173(2) Monoclinic C2/c 4 36.702(4) 12.9782(13) 15.2984(15) 90 96.892(7) 90 7234.4(13) 2.407 52 0.1060, 0.2472 0.1320, 0.2718 1.150 7092 [Rint = 0.1114]

C50H54Cd6I12N2O4S6 3136.51 173(2) Triclinic P1̅ 1 12.3013(4) 12.5433(4) 14.0707(8) 109.015(3) 93.929(2) 114.607(2) 1812.80(13) 2.873 52 0.0889, 0.1392 0.1514, 0.1574 1.035 7125 [Rint = 0.1346]

Preparation of [Cd(L)Br]2[Cd2Br6]·CH2Cl2 (1) and [Cd(L)Br]2[CdBr4]·CH2Cl2 (2). CdBr2 (23.4 mg, 0.0856 mmol) in methanol (1 mL) was added to a solution of L (20.2 mg, 0.0431 mmol) in dichloromethane (1 mL). Slow evaporation of the solution afforded a colorless needle-shaped product 1 suitable for SC-XRD analysis. The product 1 was isolated by filtration. From the slow evaporation of the filtrate for 2 weeks, a colorless block-shaped product 2 was obtained. Phase purity of the both products was confirmed by PXRD patterns. For 1. Yield: 40%. Mp: 230−232 °C. IR (KBr pellet): 3068, 3039, 2969, 2929, 1605, 1492, 1234, 1221, 1103, 1051, 1033, 791, 767 cm−1. Anal. Calc for [C50.2H54.4Br8Cd4Cl0.4N2O4S6] as [Cd(L)Br]2[Cd2Br6]· 0.2CH2Cl2: C, 29.48; H, 2.68; N, 1.37; S, 9.41. Found: C, 29.94; H, 2.77; N, 1.38; S, 9.43%. Mass spectrum m/z (FAB): 662.0 [Cd(L)Br]+. For 2. Yield: 20%. Mp: 166−170 °C. IR (KBr pellet): 3065, 2968, 2925, 1603, 1490, 1456, 1304, 1220, 1182, 1103, 1047, 1026, 765 cm−1. Anal. Calc for [C50.7H55.4Br6Cd3Cl1.4N2O4S6] as [Cd(L)Br]2[CdBr4]·0.7CH2Cl2: C, 33.54; H, 3.08; N, 1.54; S, 10.60. Found: C, 33.91; H, 3.06; N, 1.61; S, 10.21. Mass spectrum m/z (FAB): 662.0 [Cd(L)Br]+. Preparation of [Cd(L)I]2[CdI4]·CH2Cl2 (3) and [Cd(L)I]2[Cd2I6]· 0.5CH2Cl2 (4). A solution of CdI2 (31.1 mg, 0.0849 mmol) in acetonitrile (1 mL) was added to a solution of L (19.9 mg, 0.0423 mmol) in dichloromethane (1 mL). Slow evaporation of the solution afforded two types of crystalline products: initially (within 3 h) two or three drops of the brick-shaped crystals of 3 (below 1% yield) formed on the vial surface, which converted to the needle-shaped crystals of 4 (60% yield) after 1 day. One crystal of 3 was selected for the X-ray crystallographic measurements and its formula was established on the basis of the SC-XRD analysis. For 3. Anal. Calcd for [C51H56N2O4S6Cd3I6Cl2]: C, 28.85; H, 2.66; N, 1.32; S, 9.06. Found: C, 29.14; H, 2.56; N, 1.53; S, 9.21%. For 4. Yield (60%); Mp: 210−214 °C. IR (pellet): 3066, 3034, 2926, 2913, 1603, 1490, 1456, 1405, 1232, 1221, 1101, 839, 759 cm−1. [C50.5H55Cd4ClI8N2O4S6]: C, 24.79; H, 2.27; N, 1.14; S, 7.86. Found: C, 25.00; H, 2.27; N, 1.36; S, 7.83%. Mass spectrum m/z (ESI): 710.0 [Cd(L)I]+. Preparation of {[Cd(L)]2(μ-Cd4I12)} (5). CdI2 (47.5 mg, 0.130 mmol) in acetonitrile (1 mL) was added to a solution of L (20.3 mg, 0.0432 mmol) in dichloromethane (1 mL). Slow evaporation of the solution afforded a colorless crystalline product 5 suitable for SC-XRD analysis (yield: 42%). Mp 221−223 °C. IR (KBr, pellet) 3051, 3032, 2920, 2869, 2359, 2340, 1598, 1492, 1453, 1383, 1241, 1099, 1046, 1007, 753 cm−1. Anal. Calcd for [C50H54N2O4S6Cd6I12]: C, 19.15; H,

1.74; N, 0.89; S, 6.13. Found: C, 19.52; H, 1.69; N, 1.16; S, 6.13%. Mass spectrum m/z (ESI): 3009.7 [Cd6(L)2I11]+. X-ray Crystallographic Analysis. All data were collected on a Bruker SMART APEX II ULTRA diffractometer equipped with graphite monochromated Mo Kα radiation (λ = 0.71073 Å) generated by a rotating anode. Data collection, data reduction, and semiempirical absorption correction were carried out using the software package APEX2.13a All of the calculations for the structure determination were carried out using the SHELXTL package.13b In all cases, all nonhydrogen atoms were refined anisotropically and all hydrogen atoms were placed in idealized positions and refined isotropically in a riding manner along with the their respective parent atoms. Relevant crystal data collection and refinement data for the crystal structures of 1−5 are summarized in Table 1 The CIF files can be obtained free of charge from the Cambridge Crystallographic Data Centre via www. ccdc.cam.ac.uk/data_request/cif CCDC 1444584−1444588 (1−5).

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b00021. PXRD patterns and selected bond distances and angles for 1−5 (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by NRF (2012R1A4A1027750 and 2013R1A2A2A01067771). REFERENCES

(1) (a) Lindoy, L. F. The Chemistry of Macrocyclic Complexes; Cambridge University Press, Cambridge, 1989. (b) Lehn, J.-M. Supramolecular Chemistry, Concept and Perspectives; VCH, Weinheim,

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DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.inorgchem.6b00021 Inorg. Chem. XXXX, XXX, XXX−XXX