Ligand Isomer Effect on the Formations of Supramolecular Lead(II

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Ligand Isomer Effect on the Formations of Supramolecular Lead(II), Mercury(II), and Copper(II)/Mercury(II) Complexes of Bis-OS-Macrocycle 2

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Seulgi Kim, Arlette Deukam Siewe, Eunji Lee, Huiyeong Ju, InHyeok Park, Jong Hwa Jung, Yoichi Habata, and Shim Sung Lee Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b00052 • Publication Date (Web): 27 Feb 2018 Downloaded from http://pubs.acs.org on March 4, 2018

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Crystal Growth & Design

Ligand Isomer Effect on the Formations of Supramolecular Lead(II), Mercury(II), and Copper(II)/Mercury(II) Complexes of Bis-O2S2-Macrocycle Seulgi Kim,† Arlette Deukam Siewe,† Eunji Lee,† Huiyeong Ju,† In-Hyeok Park,† Jong Hwa Jung,† Yoichi Habata,*,‡ and Shim Sung Lee*,† †

Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, S. Korea Department of Chemistry and Research Center for Materials with Integrated Properties, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan ‡

ABSTRACT: In addition to ortho-isomer (o-bis-L) and meta-isomer (m-bis-L) of bis-O2S2-macrocycle obtained previously, its para-isomer (p-bis-L) was newly isolated and the complete isomer series were structurally characterized by single crystal X-ray analysis. In complexations, borderline (Pb2+) and soft (Hg2+ and Cu+) metal salts were employed to investigate the isomer effect on the coordination modes and topologies of the supramolecular complexes. Lead(II) perchlorate afforded an infinite one-dimensional (1-D) coordination polymer {[Pb2(o-bis-L)(µ-ClO4)2(ClO4)2]}n (1) and a discrete complex [Pb2(m-bisL)(CH3CN)2(H2O)2(ClO4)2](ClO4)2 (2), both of which are based on the endocyclic binuclear complexes mainly due to the oxophilicity of lead(II) ion. Meanwhile, mercury(II) halides showed an endocyclic dinuclear complex [Hg2(o-bis-L)I2][Hg3I8] (3) and an exocyclic 1-D coordination polymer [Hg3(m-bis-L)Br6]n (4) because the differences of sulfur-to-sulfur separation in the free ligand isomers might induce the different coordination modes. When a mixture of mercury(II) iodide and copper(I) iodide was used in the reaction with m-bis-L, a heterometallic 1-D coordination polymer [Cu2Hg2(m-bis-L)(µ-Cu2I2)(CH3CN)2I6]n (5) was obtained. In 5, exocyclic dicopper(I) complex units are linked by -Hg-Cu2I4-Hg- segments to form an infinite zigzag chain. Consequently, unlike the borderline metal, the soft metal ions show the sulfur-to-sulfur separation dependent coordination modes. These results demonstrate how small differences in the ligand isomers impact their self-assembled coordination products in terms of coordination mode and topological structure including dimensionality.

INTRODUCTION Structural isomers of multidentate ligands that have same chemical formula but different chemical structures so often play a key role in influencing the structures of their coordination products.1-12 In practice, changing the substitution position in the aromatic subunit in the ligand system can provide a series of regioisomers not only in linear ligands1-5 but also in cyclic analogues6-12. We have employed the above approach to NS2-macrocycles with a xylyl subunit in ortho-, meta-, and para-positions and their exocyclic soft metal complexes.8-10 In this case, the variation of the macrocyclic ring flexibilities couples with the exocyclic coordination arising from the presence of sulfur donors provides a useful and productive pathway to such new complexes displaying unusual topologies.13 On the other hand, a bis-macrocyclic scaffold is one of the host systems which can occupy two metal ions to form binuclear complexes of interest in diverse area, such as electron transport, charge transfer, and allosteric behavior in biochemical systems.14,15 Practically, 1,2,4,5tetra(bromomethyl)benzene (see Scheme 1) might be considered as an interesting platform molecule to give a series of bismacrocycle isomers depending on cyclization modes.6,11,12 Accordingly, it might be possible to obtain three regioisomers (ortho-, meta-, and para-from) via 1,2-, 1,3-, and 1,4cyclizations with linear diols or dithiols.11,12 Loeb et al reported meta-isomers of bis-thia- and bisoxathia macrocycles derived from 1,2,4,5-

tetra(bromomethyl)benzene and corresponding dithiols.6 In our recent work, the bis-cyclization reaction of 1,2,4,5tetra(bromomethyl)benzene with 3,6-dioxa-1,8-octanedithiol led to the isolation of o-bis-L and m-bis-L which form the controlled endo- and exo-coordinated 1-D polymeric products, respectively.11 More recently, we employed o-bis-L (Wshaped exo-binding site) and m-bis-L (U-shaped exo-binding site) that induce the adaptive formations of the polynuclear [CunIn] clusters as well as photoluminescence properties.12 This result shows that the exocyclic interdonor binding site alteration (S···S) can play decisive roles in the selective selfassemblies of supramolecular materials including clusters. In our previous works, however, no 1,4-bis-cyclization product (p-bis-L) was isolated nor observed in the NMR spectrum of the crude mixture.11 Thus, the detection and isolation of p-bisL have been one of the challenging tasks as a final puzzle in the study of these bis-macrocycle isomers to us. Scheme 1. Three Regioisomers of bis-O2S2-Macrocycle via 1,2-, 1,3-, and 1,4-Cyclizations.

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The continuing interest on the isomer effect of bismacrocycles and no research for p-bis-L have motivated us to extend our synthetic works to the unexplored isomer as well as their binuclear complexes with different topologies. Herein, we report an extension of these studies that form diverse types of complexes, with emphasis on the discriminated complexation behaviors of the bis-macrocycle isomers. Considering the binding affinity to the metal ions with respect to their O2S2donors, we have employed lead(II), mercury(II), and copper(I) salts as borderline and soft metal ions in present work. The isolation of p-bis-L which came in the modified reaction condition and the solid structures of the complete isomers are also reported.

(a)

RESULTS AND DISCUSSION Synthesis and Separation of p-bis-L. In our previous work,11 the reaction in Scheme 1 gave a mixture of o-bis-L and m-bisL in a 1:4 ratio. When the reactant concentration was reduced to 25% (0.55 mM), the coexistence of the three isomers (o-bisL, m-bis-L, and p-bis-L) was detected in a 1:1:4 ratio (Figure S1), indicating the high dependency of the formation of p-bisL and the distribution of the isomers on the reactant concentration. The pure p-bis-L was obtained by the two-step separation process including the solubility-dependent fractionation and the column chromatography (yield 13%, see the details in the Experimental Section). However, the overall yield for the three isomers was decreased in this condition. The 1H NMR spectra of p-bis-L exhibit the complicate coupling patterns due to its intrinsic rigid conformation of the ring cavity via the 1,4cyclization (Figures S2 and S3). However, the 13C NMR spectrum shows a simple pattern (Figure S4). Crystal Structures of the Regio-isomers. Although the crystal structures of some complexes of o-bis-L and m-bis-L have been introduced,11,12 those of the free ligands have not been reported. So, determinations of the crystal structures of the complete isomers including newly isolated p-bis-L were carried out in this work (Figure 1). Colorless crystals of o-bisL, m-bis-L, and p-bis-L were obtained by slow evaporation from the solutions of dichloromethane. It is of interest to compare the structures of the three isomers which show the different symmetries and conformations. Asymmetric unit of o-bis-L and m-bis-L contains a half molecule of the ligand due to an imposed inversion and a C2 axis, respectively. Meanwhile, the absence of symmetry in pbis-L is noted. In o-bis-L and m-bis-L, the oxygen donors are orientated in an endodentate fashion but the sulfur donors are orientated in an exodentate manner. Torsion angles of both OC-C-O and O-C-C-S segments are associated with a gauche arrangement. Unlike o-bis-L and m-bis-L, the O-C-C-S segments in p-bis-L span an anti arrangement with characteristic torsion angles. Notably, the adjacent sulfur-to-sulfur distances between two ring cavities are very different: 5.90 Å (S2···S2A) in o-bis-L, 5.37 Å (S1···S1A) and 4.84 Å (S2···S2A) in mbis-L, and 4.03 Å (S2···S4) and 4.35 Å (S1···S3) in p-bis-L.

(b)

(c) Figure 1. Crystal structures of (a) o-bis-L, (b) m-bis-L, and (c) p-bis-L. Torsion angles (deg) for o-bis-L: O1-C-C-O2 55.77(9), O1-C-C-S1 66.11(7), and O2-C-C-S2 56.79(7)], for m-bis-L: O1-C-C-O2 69.93(19), O1-C-C-S1 71.13(2), O2-CC-S2 69.85(18), for p-bis-L: O1-C-C-O2 85.33(18), O1-C-CS1 169.83(1), O2-C-C-S2 179.72(11), O3-C-C-O4 83.71(6), O3-C-C-S3 173.38(9), and O4-C-C-S4 174.53(8). Lead(II) Complexes (1 and 2). As a borderline metal cation, lead(II) perchlorate was used for the complexation of obis-L and m-bis-L. In these reactions, a dichloromethane solution of each macrocycle isomer was allowed to diffuse into acetonitrile solution of two equivalents of Pb(ClO4)2·3H2O. Slow evaporation of each solution afforded colorless crystalline products 1 for o-bis-L and 2 for m-bis-L that proved suitable for crystallography. In the crystal structures, it was found that the ortho- and meta-substitution induce the different coordination behaviors and topologies of the products as depicted in Scheme 2. The preparation of the corresponding lead(II) perchlorate complex with p-bis-L was not possible. Scheme 2. Lead(II) Complexes of the Regioisomers. O O

S

o-bis-L

O

S

Pb O

Pb

ClO4

O4Cl

Pb

S

S

Pb(ClO4)2.6H2 O S

S

Solvent

O4Cl

ClO4

O

O

Pb

Pb S

S

O

1

m-bis-L

Pb O

O

Solvent

S

S

2


S O

O

O

S

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Crystal Growth & Design The X-ray analysis revealed that 1 crystallizes in the monoclinic space group P21/n and features a one dimensional (1-D) coordination polymer with the formula {[Pb2(o-bis-L)(µClO4)2(ClO4)2]}n (Figure 2 and Table S2). In 1, each o-bis-L ligand forms a dilead(II) complex and these dinuclear complex units are further doubly linked by two bridging perchlorate ions, adopting the 1-D polymeric array. Since there is an imposed inversion at the center of the aromatic ring, the asymmetric unit of 1 contains a half molecule of o-bis-L, one lead(II) ion, and two perchlorate ions which are monodentate and bidentate. Each lead(II) ion in 1 is seven-coordinate being bound to O2S2-donors from one macrocyclic cavity adopting a dinuclear complex unit. The coordination environment is completed by two bridging perchlorate ions and one terminal perchlorate ion to yield the anion-linked 1-D coordination polymer via Pb-(µ-ClO4)2-Pb linkage. The Pb-O bond lengths [Pb1-O1 2.572(5), Pb1-O2 2.596(5) Å] in 1 are typical. While, the Pb-S bonds [Pb1-S1 2.925(2), Pb1-S2 2.962(2) Å] can be considered as weak bonds due to the intermediate behavior of the lead(II) ion between soft and hard acids. The Pb1···Pb1B distance linked by the anions is 4.94 Å which is shorter than that in the same ligand (Pb1···Pb1A 10.75 Å). This is a rare example of a 1-D coordination polymer in which dinuclear macrocyclic complex units are linked by anions.16,17 It is also noteworthy that on complexation a large conformational change of the ligand from twist (S1···S2 5.07 Å in o-bis-L, Figure 1a) to the stairway (S1···S2 4.05 Å in 1, Figure 2a) was observed mainly due to the flexible nature of the ortho-form.

(a)

(b) Figure 2. Lead(II) perchlorate complex of o-bis-L, {[Pb2(obis-L)(µ-ClO4)2(ClO4)2]}n (1) showing a 1-D polymeric structure. (a) core dinuclear coordination unit and (b) 1-D chain linked with the anions. The X-ray analysis revealed that 2 crystallizes in the monoclinic space group C2/c. In marked contrast to the infinite form in 1, compound 2 is a discrete-type 2:1 (metal-to-ligand) complex of the formula [Pb2(m-bisL)(CH3CN)2(H2O)2(ClO4)2](ClO4)2 that involves both coordinating anions and solvent molecules (Figure 3 and Table S3). Since there is an imposed inversion at the center of the aromatic ring, the asymmetric unit of the complex part in 2 contains a half molecule of m-bis-L, one lead(II) ion, one perchlorate ion, one acetonitrile, and one water molecule. The lead(II) ion in 2 is bonded to O2S2 donors of one macrocyclic cavity in

m-bis-L adopting an overall S-shape conformation. The remaining sites are occupied by one bidentate perchlorate ion, one water, and one acetonitrile to yield an overall metal coordination of eight. The bond lengths of Pb-O [2.685(2) and 2.705(2) Å] and Pb-S [3.005(7) and 3.059(7) Å] in 2 are longer than those in 1 probably due to the larger cavity size and more rigid structure of m-bis-L.

Figure 3. Lead(II) perchlorate complex of m-bis-L, [Pb2(mbis-L)(CH3CN)2(H2O)2(ClO4)2](ClO4)2 (2) showing a discrete dinuclear structure. Non-coordinating anions are omitted. The structural comparison of 1 and 2 reveals that two complexes show the similarity as well as the difference. Above all both complexes are based on the endocyclic dinuclear complex unit. In silver(I) complexation,11 o-bis-L forms an endocyclic complex, while m-bis-L allowed to prepare an exocyclic complex, due to the difference of the S···S distances.18,19 However, the same is not true for the lead(II) complexes 1 and 2. To explain this result, the borderline acidity of lead(II) should be into account.20 In the divalent metal complexes of 1,10-dithia-18-crown-6 (L), for example, PbX2 (X = ClO4, NO3) afforded endocyclic complexes [Pb(L)(ClO4)2] and [Pb(L)(NO3)2], respectively.21 In both cases, the lead(II) ion coordinates to four oxygen donors and two anions, while the distances of Pb···S (3.09-3.13 Å) can be considered as weak interactions. Similarly, the lead(II) complexations in this work are also considered to be driven by the Pb-O bond formation rather than that of the Pb-S. Consequently, the endocoordination is enthalpically more favorable for both isomers. Notably, the conformations of two isomers in 1 and 2 are different. In 1, for example, o-bis-L ligand is less folded adopting an elongated stair-shape. Thus, the resulting 1-D network 1 appears to be aided by the flexible and elongated obis-L units which seem to be more favorable for the intermolecular interaction on complexation. While, m-bis-L ligand in 2 is more folded giving a S-shape configuration which is less favorable for the intermolecular interaction. Consequently, the 1-D infinite form in 1 and the discrete form in 2 are mainly associated with the different ring rigidity of the isomers. Mercury(II) Complexes (3 and 4). In the reactions of three equivalents of mercury(II) halides with o-bis-L and m-bis-L, colorless crystalline complexes 3 (iodide) and 4 (bromide) were obtained, respectively. The yields in crystalline materials were ca. 60-70%. Single-crystal X-ray diffraction analysis revealed that two mercury(II) products feature different stoichiometry and topologies depending on their endo- and exocyclic coordination modes associated with the isomerism (Scheme 3). Scheme 3. Mercury(II) Complexes of the Regioisomers.



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S

O

S

Hg

o-bis-L O

(X = I)

O Hg

S

O

S

I

[Hg3I8]2-

Endocyclic dinuclear complex (3) Br

Hg

HgX2

Br

Br

Hg

Br

S

S

Br

Hg

m-bis-L (X = Br)

Hg

O Br

O

S S

Br

Br

S

S

O O

S

O

Br O

O Br

O

S

Hg Br

Br

O

O

O

O

S

Hg

S

Br

S S

Hg

Br

Hg

Br

Br

Exocyclic 1-D coordination polymer (4)

The X-ray analysis revealed that 3 crystallizes in the triclinic space group P-1 and features two separated parts with the formula [Hg2(o-bis-L)I2][Hg3I8]: one part is a dinuclear macrocyclic complex cation and another part is an octaiodotrimercurate(II) cluster [Hg3I8]2− anion (Figure 4 and Table S4). In the complex cation unit, each endocyclic mercury(II) atom is five-coordinate, being bound to O2S2 donors from one macrocyclic unit of o-bis-L in a stair-like arrangement. The fifth coordination site is completed by one iodide ion with the mercury(II) positioned 1.26 Å from the O2S2 plane toward the coordinating anion, adopting a perching conformation. The observed dislocation of the metal ion from the cavity center is mainly due to a smaller cavity size (14-memberd ring) for the mercury(II) ion. In the octaiodotrimercurate(II) anion cluster, three consecutive mercury(II) ions linked by iodo ligands generate a ribbon-type arrangement.22 In this, the coordination geometry of the central mercury(II) ion (Hg3) is square planar while two terminal mercury(II) ions (Hg2 and Hg2A) are tetrahedrally coordinated.

Figure 4. Mercury(II) iodide complex, [Hg2(o-bis-L)I2][Hg3I8] (3), showing two separated units. In the reaction of mercury(II) iodide with m-bis-L, an exocyclic 1-D coordination polymer of the formula [Hg3(m-bisL)Br6]n (4) was obtained (Figure 5 and Table S5). The complex 4 crystallizes in the orthorhombic space group Pnnm with Z = 2 where the asymmetric unit contains a quarter molecule of m-bis-L, one and half mercury(II) ions, and three bromide ions. In 4, there are two crystallographically different mercury(II) atoms (Hg1 and Hg2). The intercyclic Hg1 atom which lies between two macrocycle units in m-bis-L is bonded to two sulfur donors from the two ring cavities and two bromo ligands to form a dinuclear complex unit. Further, the dinuclear complex units are linked by [µ-HgBr4]2- via Hg-Br bonds [Hg2-Br2 2.9952(19) Å] to form a wavy 1-D polymeric structure. The Hg2 atom in the anionic linker unit is also fourcoordinate, being bound to four bromo ligands adopting a square planar geometry. In our previous work, m-bis-L reacts with CuI to form a polymeric chain linked by Cu2I2 cluster.12

Figure 5. Mercury(II) bromide complex of m-bis-L showing a 1-D polymeric structure, [Hg3(m-bis-L)Br6]n (4). Compared with the lead(II) complexes 1 and 2, the isomerdependent mercury(II) complexes 3 and 4 are considered to show more crystal engineering aspect. In practice, we have established several strategies to control the endo- and the exocoordination modes of the macrocycles via ligand design17,24,25 and anions26-30. We have reported the regioisomers-dependent endo- and exocyclic coordination in which the expected differences of sulfur-to-sulfur separation might induce the different coordination modes.11,12 In the present work, it is possible to confirm this hypothesis more directly because we have crystal structures of the free ligand isomers as well as their complexes. For o-bis-L, as can be seen in Figure 6, the sulfur-to-sulfur separation in one macrocycle ring (S1···S2 5.07 Å) is shorter than that between two macrocyclic rings (S1···S2A 5.90 Å). For m-bis-L, however, the sulfur-to-sulfur separation in the macrocycle ring (S1···S2 6.96 Å) is much longer than those between two macrocyclic rings (S1···S1A 4.84 and S2···S2A 5.37 Å). In the preorganized host system, the observed shorter endocyclic (o-bis-L) and exocyclic (m-bis-L) sulfur-to-sulfur distances are entropically favorable to induce the formations of endo- and exo-coordination products, respectively. On complexations with mercury(II) halides, as shown in Figure 6, some conformational changes including the sulfur-to-sulfur separation were observed in both isomers but these are less significant. Consequently, the preferred endocyclic coordination in 3 and the exocyclic coordination based polymeric structure in 4 is a good example of the crystal engineering via the soft-soft acid-base interaction in which the coordination modes might be controlled by the interdonor distances of the regioisomers.

(a)

(b) Figure 6. Comparison of sulfur-to-sulfur distances (Å) before and after dimercury(II) complexation for (a) o-bis-L and (b) m-bis-L.


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Considering the shorter S···S distances between two ring cavities [4.03 Å (S2···S4) and 4.35 Å (S1···S3) in Figure 1c], p-bis-L is expected to form exocyclic coordination products rather than endocyclic ones with soft metal ions. However, our repeated efforts to obtain such coordination products of p-bisL were not successful. In the electrostatic potential diagram of p-bis-L based on the crystal structure (Figure S5), unlike those of other isomers, the sulfur donors which locate outside the ring cavities show a relatively poor electron density. Consequently, the lower reactivity of p-bis-L might be explained by the low basicity of the soft donors together with the intrinsic rigid conformation. Heteronuclear Mercury(II)/Copper(I) Complex (5). After obtaining some homonuclear complexes of the ligand isomers, we proceeded with the reactions to prepare heteronuclear complexes. When a mixture of mercury(II) iodide and copper(I) iodide was used in a one-pot reaction with m-bis-L, a heterometallic 1-D coordination polymer of the formula [Cu2Hg2(m-bis-L)(µ-Cu2I2)(CH3CN)2I6]n (5) was obtained (Figure 7 and Table S6). The X-ray analysis revealed that 5 crystallizes in the hexagonal space group R-3 with Z = 18 where the asymmetric unit contains a half molecule of m-bisL, one mercury(II) ion, two copper(I) ions, four iodide ions, and one acetonitrile molecule. The overall structural topology and the connectivity pattern of 5 is similar to those of the mercury(II) bromide complex 4. For example, two copper(I) (Cu1 and Cu1A) bind to the ligand in the exo-coordination mode as two mercury(II) bind in 4. The major difference between 4 and 5 is a bridging part which links the dinuclear complex units. In 5, the dicopper(I) macrocyclic units are linked by heteronuclear I-Hg-I-(Cu2I2)-IHg-I units via Cu-I bonds (Cu1-I1 2.6438(18) Å) resulting in the formation of a wavy 1-D polymeric structure which are also linked by Cu2I2 square via Cu-S bond (Cu2-S1 2.309(3) Å). In 5, the intercyclic Cu2 atom is bonded to two sulfur donors, one acetonitrile molecule, and one bridging bromo ligand adopting a distorted tetrahedral environment. The distance between two intercyclic cations in 5 (Cu1···Cu1A 8.33 Å) is shorter than that in 4 (Hg1···Hg1B 9.00 Å). The Cu1 atom in the square-type [Cu2I2] cluster is also four-coordinate, being bound to three iodo ligands and one sulfur atom of the macrocycle. The Hg1 atom which links two different copper(I) ions is three-coordinate, being bound to two bridging iodo ligands and one terminal iodo ligand. The exo-coordination mode has been utilized as a powerful tool to link the macrocycles or their complex units to prepare not only the homonuclear infinite complexes but also the heteronuclear ones.13 For instance, our group have reported several heteronuclear type [Na(I)/Cu(I)30, K(I)/Cu(I)31,32, K(I)/Hg(II)31,33,34, K(I)/Cd(II)31, and Ag(I)/Pd(II)35] infinite complexes with a range of macrocyclic ligands. To the best of our knowledge, 5 is the first characterized infinite heteronuclear macrocyclic complex of these two metal ions. As shown in Figure 7b, the 1-D chains are arranged in a parallel manner with the cross section of hexagonal channels to give a pseudo 3-D structure. In 5, total potential solvent area volume obtained by PLATON36-38 is 2750.3 Å3 which is 20.2% of the unit cell volume 13610.1 Å3.

(a)

(b) Figure 7. Heteronuclear Hg(II)/Cu(I) complex of m-bis-L, [Cu2Hg2(m-bis-L)(µ-Cu2I2)(CH3CN)2I6]n (5): (a) 1-D polymeric structure and (b) packing structure showing a pseudo-3D framework with hexagonal channels along the c-axis.

CONCLUSION Since the coordination modes of the proposed bis-O2S2macrocycle isomers are expected to be dictated by the donor arrangement in each isomer, it is challenging to isolate the complete isomer series as well as their complexes. In addition to ortho-isomer (o-bis-L) and meta-isomer (m-bis-L), the para-isomer (p-bis-L) was isolated and the complete isomers were structurally characterized in the solid state. In complexations with lead(II) and mercury(II) salts, the different isomers not only alter the coordination modes but also the topologies. A new type of the heteronuclear infinite complex of m-bis-L was also isolated but no complexes of p-bis-L were obtained. The present study demonstrates how small changes in the structural isomerism impact their overall topological. In particular, the exo-coordination mode has been utilized as a powerful tool to link the complex units to prepare not only the homonuclear infinite complexes but also the heteronuclear ones.

EXPERIMENTAL SECTION General. All chemicals and solvents used in the syntheses were of reagent grade and were used without further purification. NMR spectra were recorded on a Bruker 300 spectrometer (300 MHz). The FT-IR spectra were measured with a Nicolet iS10 spectrometer. The elemental analysis was carried out on a LECO CHNS-932 elemental analyzer. The electrospray ionization (ESI) mass spectra were obtained on a Thermo Scientific LCQ Fleet spectrometer. Synthesis, Separation, and Characterization of p-bis-L. 1,2,4,5-tetra(bromomethyl)benzene (0.50 g, 1.11 mmol) and 3,6-dioxa-1,8-octanedithiol (0.51 g, 2.80 mmol) were dissolved in DMF (50 mL) and added over one day, to a suspen-



sion of Cs2CO3 (2.17 g, 6.67 mmol) in DMF (2000 mL) stirring at 55 °C. Upon completion of addition, the DMF was removed and the resulting yellow residue was dissolved in CH2Cl2 (100 mL) and filtered. The CH2Cl2 solution was washed with 0.1 M NaOH (2 × 100 mL) and deionized water (100 mL) then dried over anhydrous MgSO4. The 1H-NMR spectrum of the crude product revealed the presence of the three isomers (o-bis-L, m-bis-L, and p-bis-L) in a 1:1:4 ratio. However, it was not possible to separate p-bis-L from other isomers by the column chromatography on silica gel (40% ethyl acetate /hexane) directly due to the very similar Rf values (especially with m-bis-L): o-bis-L (0.30), m-bis-L (0.44), and p-bis-L (0.41). So the following two-step process was employed. First, by using the lower solubility of m-bis-L than other isomers in CH2Cl2, the solid mixture was filtrated on the glass filter to separate the CH2Cl2-soluble and insoluble components. The soluble component proved to be a mixture of obis-L and p-bis-L together with a trace amount of m-bis-L (by means of combined TLC and NMR analysis). After m-bis-L was removed from the mixture, then the gradient elution (from 10% ethyl acetate/hexane to 40% ethyl acetate/hexane) of the column chromatography of this mixture on silica gel led to the isolation of pure p-bis-L (70 mg, 13%) as a colorless solid. For p-bis-L. Mp: 188-189 °C. 1H NMR (300 MHz, CDCl3): δ 7.12 (s, 2 H, Ar), 4.30-3.68 (dd, 8 H, ArCH2S), 3.32 (s, 8 H, OCH2CH2O), 3.16-2.99 (m, 8 H, OCH2CH2S), 2.61-2.44 (m, 8 H, SCH2CH2O); 13C NMR (75 MHz, CDCl3) 136.2, 134.0, 70.6, 70.5, 34.1, 30.5; IR (KBr pellet): 3009, 2862, 1500, 1471, 1429, 1369, 1351, 1293, 1228, 1193, 1112, 1033, 977, 917, 907cm-1; Anal. Calcd for [C22H34O4S4]: C, 53.84; H, 6.98; S, 26.13. Found: C, 54.11; H, 7.07; S, 26.17%. ESI Mass spectrum m/z: 394.08 [M+H]+. Preparation of 1, {[Pb2(o-bis-L)(µ-ClO4)2(ClO4)2]}n. Pb(ClO4)2·3H2O (31.5 mg, 0.078 mmol) in acetonitrile (1 mL) was added to a solution of o-bis-L (15.0 mg, 0.031 mmol) in chloroform (1 mL). Slow evaporation of the solution afforded a colorless crystalline product 1 suitable for X-ray analysis. IR (KBr pellet): 2937, 2889, 1618, 1459, 1450, 1381, 1296, 1247, 1127 (ClO4-), 1111, 1044, 1001, 973, 959, 916, 627 cm-1 Anal. Calcd for [C22H34Cl4O20Pb2S4]: C, 20.28; H, 2.63; S, 9.84. Found: C, 20.54; H, 2.61; S, 9.90%. (Explosive!) Preparation of 2, [Pb2(m-bisL)(CH3CN)2(H2O)2(ClO4)2](ClO4)2. Pb(ClO4)2·3H2O (31.5 mg, 0.078 mmol) in acetonitrile (1 mL) was added to a solution of m-bis-L (15.0 mg, 0.031 mmol) in chloroform (1 mL). Slow evaporation of the solution afforded a colorless crystalline product 2 suitable for X-ray analysis. IR (KBr pellet) 2914, 2887, 1595, 1509, 1469, 1351, 1248, 1129 (ClO4), 1105, 1030, 908, 874, 798, 735, 627 cm-1; Anal. Calcd for [C26H44Cl4N2O22Pb2S4]: C, 21.98; H, 3.12; N, 1.97; S, 9.02. Found: C, 21.79; H, 3.12; N, 2.01; S, 8.97%. (Explosive!) Preparation of 3, [Hg2(o-bis-L)I2][Hg3I8]. HgI2 (35.2 mg, 0.077 mmol) in methanol (1 mL) was added to a solution of obis-L (15.0 mg, 0.031 mmol) in chloroform (1 mL). Slow evaporation of the solution afforded a yellow crystalline product 3 suitable for X-ray analysis. Mp: 212-213 °C. IR (KBr pellet) 2883, 2863, 1655, 1397, 1366, 1287, 1243, 1134, 1118, 1100, 1026, 1008, 908, 751 cm-1; Anal. Calcd for [C22H34Hg5I10O4S4]: C, 9.56; H, 1.24; S, 4.64. Found: C, 9.21; H, 1.34; S, 4.36%. Preparation of 4, [Hg3(m-bis-L)Br6]n. HgBr2 (27.9 mg, 0.077 mmol) in methanol (1 mL) was added to a solution of m-bis-L (15.0 mg, 0.031 mmol) in chloroform (1 mL). Slow

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evaporation of the solution afforded a colorless crystalline product 4 suitable for X-ray analysis. Mp: 219-220 °C. IR (KBr pellet) 3036, 2952, 2899, 2862, 1475, 1443, 1399, 1385, 1295, 1278, 1157, 1134, 1106, 1080, 1023, 966, 857, 780 cm-1; Anal. Calcd for [C22H34Br6Hg3O4S4]: C, 16.81; H, 2.18; S, 8.16. Found: C, 16.62; H, 2.51; S, 8.25%. Preparation of 5, [Cu2Hg2(m-bis-L)(µCu2I2)(CH3CN)2I6]n. HgI2 (35.2 mg, 0.077 mmol) in methanol (0.7 mL) and CuI (14.8 mg, 0.078 mmol) acetonitrile (0.7 mL) was added to a solution of m-bis-L (15.0 mg, 0.031 mmol) in chloroform (1 mL). Slow evaporation of the solution afforded a yellow crystalline product 5 suitable for X-ray analysis. Mp: 226-227 °C (decomp.). IR (KBr pellet) 2858, 1655, 1638, 1459, 1439, 1398, 1350, 1130, 1100, 1068, 1030, 860, 805, 733 cm-1; Anal. Calcd for [C13H20Cu2HgI4NO2S2]: C, 13.92; H, 1.80; N, 1.25; S, 5.72. Found: C, 13.68; H, 1.80; N, 1.25; S, 5.72%. X-Ray Crystallographic Analysis. Crystal data were collected on a Bruker SMART APEX II ULTRA diffractometer equipped with graphite monochromated Mo Kα radiation (λ = 0.71073 Å). Data collection, data reduction, and semiempirical absorption correction were carried out using the software package of APEX2.39 All of the calculations for the structure determination were carried out using the SHELXTL package.40 In 4, some ghost peaks were found close to the Hg atoms. Since the lattice water molecule in 5 is highly disordered, the contribution of solvent electron density was removed by the SQUEEZE routine in PLATON.41 Relevant crystal data collection and refinement data for the crystal structures are summarized in Table S1.

ASSOCIATED CONTENT Supporting Information NMR spectra and crystal structural data. CCDC reference numbers 921860 (o-bis-L), 921861 (m-bis-L), 1588397 (p-bis-L), 1588398 (1), 1588399 (2), 1588400 (3), 1588401 (4), 1588402 (5). These materials are available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (S.S.L.) *E-mail: [email protected] (Y.H.)

ORCID Shim Sung Lee: 0000-0002-4638-5466 Yoichi Habata: 0000-0003-0712-6231

Notes The authors declare no competing financial interests.

ACKNOWLEDGMENT This work was supported by NRF (2016R1A2A205918799 and 2017R1A4A1014595), S. Korea, and the Support Program for Strategic Research Foundation at Private Universities (2012-2016) and JSPS KAKENHI Grant Number JP17K05844, Japan.

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For Table of Contents Use Only

Ligand Isomer Effect on the Formations of Supramolecular Lead(II), Mercury(II), and Copper(I)/Mercury(II) Complexes of BisO2S2-Macrocycle Seulgi Kim,† Arlette Deukam Siewe,† Eunji Lee,† Huiyeong Ju,† In-Hyeok Park,† Jong Hwa Jung,† Yoichi Habata,*,‡ and Shim Sung Lee*,†

In order to investigate the ligand isomer effect on the complexations, three regioisomers of bis-O2S2macrocycle (o-bis-L, m-bis-L, and p-bis-L) were employed. The structural characteristics of the resulting homonuclear and heteronuclear supramolecular complexes of the isomers were discussed in terms of controlling factors and coordination modes.

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Ligand Isomer Effect on the Formations of Supramolecular Lead(II

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