Box-like Heterometallic Macrocycles Derived from Bis-Terpyridine

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Box-like Heterometallic Macrocycles Derived from Bis-Terpyridine Metalloligands Jing-Jing Liu, Yue-Jian Lin, and Guo-Xin Jin* Shanghai Key Laboratory of Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, Shanghai 200433, China S Supporting Information *

ABSTRACT: A series of [4+2] hexanuclear heterometallic macrocycles, {[Cp*2Ir2(μ-DHNA)]2[Zn(pyterpy)2]2(OTf)2}·(OTf)6 (1a), {[Cp * 2 Ir 2 (μ-DHNA)] 2 [Zn(pyterpy) 2 ] 2 }·(SbF 6 ) 8 (1a′), {[Cp* 2 Rh 2 (μ-DHNA)] 2 [ Z n ( p y t er py ) 2 ] 2 }· (OTf) 8 (1 b ), {[Cp* 2 Ir 2 (μ-DHNA)] 2 [Ni(pyterpy) 2 ] 2 (OTf) 2 }·(OTf) 6 (2a), { [ Cp * 2 R h 2 ( μ- DH NA) ] 2 [ N i ( p y t e r p y ) 2 ] 2 } · (O Tf) 8 ( 2 b ) , {[Cp*2Ir2(μ-DHNA)]2[Cu(pyterpy)2]2}·(PF6)4(OTf)4 (3a), and {[Cp*2Rh2(μ-DHNA)]2[Cu(pyterpy)2]2}·(PF6)4(OTf)4 (3b), have been constructed by the self-assembly of half-sandwich organometallic units [(Cp*2M2(μ-DHNA)Cl2] (M = Ir and Rh; Cp* = η5pentamethylcyclopentadienyl; DHNA = 6,11-dihydroxy-5,12-naphthacenedione) and the metalloligands [M(pyterpy)2]2+ (M = Zn, Ni, and Cu; pyterpy = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine). Confirmed by single-crystal X-ray analysis, complexes 1a−3b display hexanuclear heterometallic macrocycles with two box-like cavities. Interestingly, on the basis of the different combinations of metals, complexes 1a and 2a have the ability to encapsulate two OTf − guest anions in the molecular cavities, but differ from that of the other complexes in which all counteranions exist outside the molecular backbones. In addition, the reaction of [Cp*MCl2]2 (M = Ir and Rh) and [Ni(pyterpy)2](NO3)2 leads to the formation of [2+1] trinuclear heterometallic linear molecules {Cp*2Ir2[Ni(pyterpy)2]Cl4}(NO3)2 (4a) and {Cp*2Rh2[Ni(pyterpy)2]Cl4}(NO3)2 (4b), which could be used as a kind of precursor.

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INTRODUCTION

Organometallic macrocycles have attracted increasing attention due to the aesthetic appeal of their triangles, squares, cages, and other polyhedra and great potential applications in the area of catalysis, selective recognition, and host−guest chemistry.1−5 The incorporation of metal centers or organic linkers into these macrocycles could impart novel functionality and complexity to these systems.6,7 Moreover, the design of molecular materials and devices based on multimetallic arrays supported by polydentate ligands has seen explosive growth, particularly in the formation of various heterometallic macrocycles derived from rich metalloligands.8−13 Generally, substituted pyridines are prominent building blocks with rich coordination properties.14−16 4′-(4-Pyridyl)-2,2′:6′,2″-terpyridine (pyterpy) has been intensively explored due to its interesting properties and multifunctional coordination modes, and it has a strong ability to chelate metal centers to form ideal precursors [M(pyterpy)2]n+.17 On the other hand, many researchers including us have extensively explored half-sandwich organometallic {Cp*M} (M = Ir and Rh; Cp* = η5-pentamethylcyclopentadienyl) fragments acting as metal corners in the construction of macrocycles for their advantages in solubility, thermal stability, and flexibility with a three-legged piano-stool shape. A variety of halfsandwich Ir- and Rh-based organometallic macrocycles such as © 2014 American Chemical Society

tetranuclear rectangular molecules, hexanuclear prisms, and octanuclear organometallic boxes have been designed.4,18−21 Recently, our group has developed a range of functional macrocyclic architectures by various half-sandwich organometallic units and metalloligands drived by the self-assembly approach.7 Herein, we report on the synthesis and characterization of the novel [4+2] hexanuclear heterometallic macrocycles employing [M(pyterpy)2]2+ (M = Zn, Ni, and Cu) species and half-sandwich organometallic [(Cp* 2M 2 (μDHNA)Cl2] (M = Ir and Rh; DHNA = 6,11-dihydroxy-5,12naphthacenedione) units (see Figure 1). Characterized by single-crystal X-ray diffraction, complexes 1a−3b possess a boxlike structure, which successfully extends rectangular frameReceived: January 26, 2014 Published: February 25, 2014 1283

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further study the templating effect of different anions in the system, based on the complex 1a under similar conditions, but with AgBF4 or AgSbF6 salts,22 we observed that much larger SbF6− ions favored the formation of hexanuclear heterometallic macrocycles such as complex {[Cp*2Ir2(μ-DHNA)]2[Zn(pyterpy)2]2}·(SbF6)8 (1a′). Then they were further verified by 1H NMR, IR, and elemental analysis. In addition, complexes {Cp*2Ir2[Ni(pyterpy)2]Cl4}(NO3)2 (4a) and {Cp*2Rh2[Ni(pyterpy)2]Cl4}(NO3)2 (4b) are [2+1] trinuclear heterometallic linear molecules supported by [Cp*MCl2]2 (M = Ir and Rh) and [Ni(pyterpy)2](NO3)2 ligands.

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Figure 1. [M(pyterpy)2]2+ species and half-sandwich organometallic [(Cp*2M2(μ-DHNA)Cl2] units.

RESULTS AND DISCUSSION Synthesis and Characterization of Heterometallic Macrocycle Assemblies. As a part of an ongoing project to study half-sandwich organometallic macrocycles or cages, our efforts began by exploring substituted polypyridine ligands in this system to acquire some novel results. Then we used a series of [M(pyterpy)2]2+ metalloligands as starting reactants, whereby two terpyridine ligands chelate the M2+ ion (M = Zn, Ni, and Cu) using tridentate pyridyl sites to form a monomer, leaving the pendant monodentate pyridyl site for further coordination. Also we continued to explore the extended aromatic ring systems. Luckily, when 6,11-dihydroxy-5,12naphthacenedione (H2DHNA) as bridging ligand and halfsandwich organometallic {Cp*M} (M = Ir and Rh) fragments as metal corners were used, a series of novel [4+2] hexanuclear heterometallic macrocycles with two box-like cavities were

works to the third dimension by introducing the H2DHNA ligand. Complexes {[Cp*2Ir2(μ-DHNA)]2[Zn(pyterpy)2]2(OTf)2}·(OTf)6 (1a) and {[Cp*2Ir2(μ-DHNA)]2[Ni(pyterpy)2]2(OTf)2}·(OTf)6 (2a) have the ability to selectively encapsulate two OTf− guest anions in the box-like cavities. However, for complexes {[Cp*2Rh2(μ-DHNA)]2[Zn(pyterpy)2]2}·(OTf)8 (1b) and {[Cp*2Rh2(μ-DHNA)]2[Ni(pyterpy)2]2}·(OTf)8 (2b), eight counteranions all exist in the outer pockets, but also differ from those of complexes {[Cp*2Ir2(μ-DHNA)]2[Cu(pyterpy)2]2}·(PF6)4(OTf)4 (3a) and {[Cp*2Rh2(μ- DHNA)]2[Cu(pyterpy)2]2}·(PF6)4(OTf)4 (3b), in which four OTf− and four PF6− anions as cobalanced counteranions are outside the molecular backbone. In order to

Scheme 1. Synthetic Route of Hexanuclear Heterometallic Macrocycles 1a−3b

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of its polycrystallinity. In this system, other complexes were fully characterized by single-crystal X-ray diffraction. Complexes 1a−3b are [4+2] hexanuclear heterometallic macrocycles with a box-like structure. Complexes 1a and 2a both encapsulate two OTf− anions as guests in the molecular cavities. However, for complexes 1a′, 1b, and 2b, all eight counteranions (SbF6− for 1a′; OTf− for 1b and 2b) exist outside the molecular backbones. Complexes 3a and 3b involve four OTf− and four PF6− anions as cobalanced counteranions out of the macrocycles. Complexes 4a and 4b are [2+1] trinuclear heterometallic linear molecules. Complex 1a is a hexanuclear heterometallic macrocycle based on a [4Ir+2Zn] core with two box-like cavities. It is crystallized in the monoclinic space group P2(1)/c. As shown in Figure 2, four Ir atoms in 1a are located in the four vertices of the rectangular structure assembled by [Zn(pyterpy)2]2+ and DHNA2− edges. The {Cp*Ir} fragments adopt a classical threelegged piano-stool geometry, in which Ir atoms are coordinated by one Npyridyl atom from [Zn(pyterpy)2]2+ and two O atoms from the DHNA2− bridging ligands. Also, complex 1a has a distorted “ZnN6” octahedron environment. The Zn center is chelated by Npyridyl atoms from the central terpy units. The distances of the adjacent Ir atoms along the edges are 8.41 (Ir(1)−Ir(2)) and 22.29 (Ir(1)−Ir(2A)) (A 1−x, −y, 1−z) Å, respectively, and the lengths of Ir(1)−Zn(1) and Zn(1)− Ir(2A) are 11.15 and 11.18 Å, which lead to the formation of two cavities of 9.69 × 8.41 × 11.15 (11.18) Å. Moreover, the three pyridine rings coordinated with the Zn center are close to planar, and the pendant pyridine rings are twisted away from the terpy plane by about 31.3° and 38.9°, respectively. The DHNA2− ligands as building blocks are distorted inward by about 18.2°. Importantly, the hydrogen bonds between the three O atoms from the OTf− guest anions and hydrogens from the pyridine rings in the molecular backbone are in the range of 2.284−2.967 Å. Relevant bond distances and angles for 1a are summarized in Table S1. In addition, complex 1a′ also shows a box-like structure consistent with that of complex 1a, which is separated by pyterpy ligands to form two cavities of 9.71 × 8.35 × 11.18 (11.16) Å, while the DHNA2− ligands are twisted inward by about 18.0° and the pendant pyridine rings are not coplanar with the central terpy units but twisted by 30.8° and 56.8°, respectively (see Figure S2 and Table S2). From the viewpoint of the size of the cavities, they are a little narrower than those of complex 1a. It is of note, compared with 1a, that eight SbF6− counterions from complex 1a′ are in the outer hosts. Complex 1b displays a [4Rh+2Zn] hexanuclear heterometallic macrocycle formed by [Cp*2Rh2(μ-DHNA)Cl2] and [Zn(pyterpy)2]2+ building blocks. Similarly, as shown in Figure 3, all of the Rh atoms show three-legged piano-stool geometries with O2N donor sets and one Cp* fragment. The zinc center exists in a “ZnN6” core, coordinated by the tridentate terpy domains of two pyterpy ligands. Four {Cp*Rh} vertices reside on the edges of the rectangular structure with distances of 8.44 (Rh(1)−Rh(2)) and 22.39 (Rh(1)−Rh(2A)) (A 1−x, 1−y, 1− z) Å, respectively. The Rh(1)−Zn(1) and Zn(1)−Rh(2A) distances along the edges average 11.20 and 11.19 Å, respectively. The pendant pyridine rings are twisted by 23.2° and 49.3° out of the plane of the terpy unit. Relevant bond distances and angles for 1b are summarized in Table S3. The size of the box-like cavities in 1b is 9.81 × 8.44 × 11.20 (11.19) Å, which is much larger than those of complexes 1a and 1a′. Instead of SbF6− anions from complex 1a′, eight OTf−

obtained in moderate yields. In detail, following a stepwise formation method, as shown in Scheme 1, the reactions of [Cp*MCl2]2 (M = Ir and Rh) and H2DHNA ligands with the assistance of CH3ONa in a 1:1:2 ratio in methanol at room temperature gave the binuclear [Cp*2M2(μ-DHNA)Cl2] complexes, and then the coordination-unsaturated intermediates were formed with addition of excess, different silver salts to the bimetallic complexes in methanol, which allowed them to adopt syn geometry to coordinate with the [M(pyterpy)2]2+ (M = Zn, Ni, and Cu) in a 1:1 molar ratio. Suitable crystals for the X-ray crystallography of complexes 1a−3b were obtained by slow diffusion of ether into a solution of these complexes in acetonitrile. For complexes 4a and 4b, as shown in Scheme 2, they were synthesized by [Cp*MCl2]2 (M = Ir and Rh) reacting with [Ni(pyterpy)2](NO3)2 in a 1:1 molar ratio in mixed solvents (4a: MeOH/CH3CN; 4b: MeOH/CH2Cl2), respectively. Scheme 2. Synthetic Route of Trinuclear Heterometallic Linear Molecules 4a and 4b

In the IR spectrum, for complexes 1a−3b, they all exhibit a strong band of μ-CO from the DHNA2− ligand near 1542 cm−1 4 and a group of characteristic bands near 1384 and 794 cm−1 attributed to the pyterpy ligand.17,23 Also strong absorptions of OTf− anions appeared at 1260, 1030, and 639 cm−1, respectively.22−26 In contrast, the absorptions of SbF6− counteranions from complex 1a′ are observed at 1248 and 1015 cm−1, but complexes 3a and 3b both have an extra peak near 845 and 558 cm−1 attributed to PF6− anions.27 All IR analyses are in good agreement with their compositions. While complexes 1a, 1a′, and 1b with a Zn center are further confirmed by 1H NMR spectra, the features of these complexes are signals of Cp* fragments at δ 1.77, 1.77, and 1.82 ppm, respectively. Obviously, the 1H NMR spectrum of complex 1a is qualitatively very similar to those of the corresponding complexes 1a′ and 1b, which indicates that they have similar backbone structures (see Figure S1). Molecular Structures. Single crystals were obtained for all compounds except for complex 4a. In the case of 4a, we failed to collect a suitable set of data for full characterization because 1285

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Figure 2. (a) Crystal structure of the cationic backbone [1a⊃2OTf]6+ (1a6+). H atoms, anions, and solvent molecules were omitted for clarity. (b) View of 1a6+ in space-filling mode, showing a crowded environment. (c) Perspective image showing the rectangular structure of 1a6+. (d) Hydrogen bonds between the OTf− guest anions and hydrogens from the pyridyl rings in the molecular backbone (pink for Ir, orange for Zn, blue for N, red for O, yellow for S, green for F, gray for C).

Figure 3. (a) Crystal structure of complex 1b. H atoms, anions, and solvent molecules were omitted for clarity. (b) Simplified view of 1b in wires mode. (c) View of 1b in space-filling mode. (d) Perspective image showing the rectangular structure of 1b (violet for Rh, orange for Zn, blue for N, red for O, gray for C).

counterions exist outside the molecular backbone in 1b. We reasoned that the size of the cavity and the guest size match could be the determining factors for the ability to enclose guest anions in these pores. In an attempt to determine the effects of the metal centers, we also studied other substrates and whether the formation of heterometallic macrocycles and the encapsulation of guests occurred or not, and when the Zn center was displaced by Ni

and Cu centers under similar conditions, we obtained all [4+2] hexanuclear heterometallic macrocycles with two “boxes” as expected. For 2a and 2b, with Ni centers, their structures and the ability of encapsulating guests are identical to those of complexes 1a and 1b, with Zn centers, whereas with Cu centers, complexes 3a and 3b both have a similar box-like structure, but possess two kinds of OTf− and PF6− counteranions outside the backbones. 1286

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Figure 4. Crystal structure of the complex 3a. H atoms and solvent molecules were omitted for clarity (pink for Ir, turquiose for Cu, blue for N, red for O, yellow for S, green for F, brown for P, gray for C).

Figure 5. Crystal structure of complex 4b. H atoms, anions, and solvent molecules were omitted for clarity (violet for Rh, green for Ni, blue for N, rose for Cl, gray for C).

X-ray structural analysis reveals that complexes 2a and 2b crystallize in the monoclinic space groups P2(1)/c. They have a box-like structure with cavities of 9.69 × 8.40 × 11.06 (1.08) Å (2a) and 9.80 × 8.44 × 11.12 (11.10) Å (2b), respectively. Further, {Cp*Ir} and {Cp*Rh} have identical coordination geometries to those of complexes 1a and 1b, with Zn centers. The Ni centers in 2a and 2b are chelated by six Npyridyl atoms from two pyterpy ligands in a distorted octahedron with a “NiN6” core. The distances of the adjacent Ir or Rh atoms in 2a and 2b are 22.10 (Ir(1)−Ir(2A)) (A 1−x, −y, 1−z) Å and 22.22 (Rh(1)−Rh(2A)) (A 1−x, 1−y, 1−z) Å, respectively. In contrast to complex 1a, the hydrogen bonds between O atoms from the OTf− guest anions and hydrogens from the pyridyl rings in the molecular backbone of 2a are in the range of 2.267−2.947 Å. The DHNA2− ligands are twisted inward about 18.1° and the pendant pyridine rings are twisted by 30.2° and 39.1° out of the terpy planes in 2a, respectively. However, for complex 2b, the pendant pyridine rings are twisted away from the plane of the central pyridine rings by 23.9° and 48.3°, respectively (for details see the Supporting Information). X-ray structural analysis also reveals that complexes 3a and 3b crystallize in the monoclinic space groups P2(1)/c. As shown in Figure 4, the {Cp*Ir} fragments in 3a adopt a classical three-legged piano-stool geometry in which Ir atoms are coordinated by one Npyridyl atom from [Cu(pyterpy)2]2+, and two O atoms from the DHNA2− ligand. The Cu centers are also six-coordinate, bonded by the tridentate terpy domains of two pyterpy ligands. Complexes 3a and 3b have a similar chemistry environment (see Figure S5 and Figure S6). The Ir··· Ir distances along the edges in 3a are 8.43 (Ir(1)−Ir(2)) and 22.12 (Ir(1)−Ir(2A)) (A −x, 2−y, 1−z) Å, respectively. For complex 3b, the distances of the adjacent Rh atoms are 8.43 (Rh(1)−Rh(2)) and 22.18 (Rh(1)−Rh(2A)) (A −x, 1−y, −z) Å, respectively. The pendant pyridine rings are twisted by 22.7° and 45.0° out of the terpy plane in 3a (3b: 25.3° and 44.0°), respectively (see Table S6 and Table S7). It is noteworthy that complexes 3a and 3b both have four OTf− and four PF6−

anions as exterior cobalanced counteranions. The resulting assembly method could, we hypothesized, be that Cu(pyterpy)2(PF6)2 as starting materials introduce PF6− anions into the system, which are much larger than NO3− anions from Zn(pyterpy)2(NO3)2 and Ni(pyterpy)2(NO3)2. In contrast to small anions such as NO3−, large anions such as PF6− and OTf− anions, existing as counteranions, have a templating effect on the formation of heterometallic macrocycles and also a different binding capacity of anions, which all result in complexes 3a and 3b, contain two different counteranions. However, the size of PF6− and OTf− anions does not match the molecular cavities (3a: 9.74 × 8.43 × 11.04 (11.08) Å; 3b: 9.78 × 8.43 × 11.11 (11.06) Å). Complex 4b crystallizes in the monoclinic space groups C2/ c. It is a [2Rh+Ni] trinuclear heterometallic linear molecule. As shown in Figure 5, the {Cp*Rh} fragments adopt a classical three-legged piano-stool geometry in which Rh atoms are coordinated by one Npyridyl atom from the [Ni(pyterpy)2]2+ group and two Cl atoms. The distance between the adjacent Rh atoms is 22.19 Å. The lengths of Rh(1)−Ni(1) and Rh(2)− Ni(1) are 11.08 and 11.15 Å, respectively. The pendant pyridine rings are twisted by 7.1° and 29.2° out of the terpy plane, which is much smaller than that of hexanuclear heterometallic macrocycles mentioned above. Relevant bond distances and angles for 4b are summarized in Table S8. Templating Effect of Anions. To determine the effects of different anions on the formation of hexanuclear heterometallic macrocycles with a box-like structure and the ability of encapsulating guests within the cavities, we chose complex 1a for the following studies because the corresponding compounds with a Zn center were easier to characterize by 1H NMR. Then following the titration of different silver salts such as AgBF4 and AgSbF6 in the process of preparing them under identical conditions, we found that when BF4− anions were introduced to the system, the structure of heterometallic macrocycles with two “boxes” could not be formed, as confirmed by 1H NMR. In contrast to complex 1a, 1H NMR indicated that no new peaks 1287

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filtrate, and the mixture continued to stir for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 40 mg (65%). 1H NMR (400 MHz, CD3OD, ppm): 8.93−8.97 (m, 16H; H1, H3), 8.86−8.88 (q, 8H4), 8.52 (d, J = 8 Hz, 8H1′), 8.15 (d, J = 6.4 Hz, 8H2), 8.00−8.02 (q, 8H2′), 7.68−7.72 (m, 16H; H5, H7), 6.86−6.89 (m, 8H6), 1.82 (s, 60H; Cp*). IR (KBr disk): 3074(w), 2922(w), 1605(m), 1575(w), 1542(s), 1477(w), 1452(w), 1384(vs), 1283(s), 1257(s),1224(m), 1161(m), 1078(w), 1056(w), 1030(s), 934(w), 831(w), 794(m), 733(m), 657(w), 639(s), 574(w), 516(w) cm−1. Anal. Calcd (%) for C164H132N16O32S8F24Rh4Zn2: C 48.12, H 3.25, N 5.47. Found: C 48.38, H 3.01, N 5.74. Crystals of 1b suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 1b in acetonitrile after several days. Synthesis of 2a. A mixture of [(Cp*2Ir2(μ-DHNA)Cl2] (0.03 mmol, 30.4 mg) and AgOTf (0.12 mmol, 30.8 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Ni(pyterpy)2](NO3)2 (0.03 mmol, 24.1 mg) was added to the filtrate, and the mixture was stirred for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 41 mg (62%). IR (KBr disk): 3073(w), 2921(w), 1614(m), 1573(w), 1541(vs), 1475(m), 1453(m), 1410(s), 1385(vs), 1339(w), 1274(vs), 1258(vs), 1224(m), 1158(s), 1078(w), 1059(w), 1030(vs), 936(m), 833(w), 794(m), 754(w), 733(m), 639(vs), 574(w), 517(w) cm−1. Anal. Calcd (%) for C164H132N16O32S8F24Ir4Ni2: C 44.39, H 3.00, N 5.05. Found: C 44.24, H 3.07, N 5.24. Crystals of 2a suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 2a in acetonitrile after several days. Synthesis of 2b. A mixture of [(Cp*2Rh2(μ-DHNA)Cl2] (0.03 mmol, 25.1 mg) and AgOTf (0.12 mmol, 30.8 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Ni(pyterpy)2](NO3)2 (0.03 mmol, 24.1 mg) was added to the filtrate, and the mixture was stirred for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 39.8 mg (65%). IR (KBr disk): 3070(w), 2923(w), 1605(m), 1572(w), 1542(vs), 1475(w), 1451(w), 1384(vs), 1333(w), 1271(m), 1259(m), 1223(w), 1158(m), 1056(w), 1030(s), 934(m), 830(w), 795(m), 733(m), 657(w), 638(s), 574(w), 517(w) cm−1. Anal. Calcd (%) for C164H132N16O32S8F24Rh4Ni2: C 48.27, H 3.26, N 5.49. Found: C 48.01, H 3.56, N 5.29. Crystals of 2b suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 2b in acetonitrile after several days. Synthesis of 3a. A mixture of [(Cp*2Ir2(μ-DHNA)Cl2] (0.03 mmol, 30.4 mg) and AgOTf (0.12 mmol, 30.8 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Cu(pyterpy)2](PF6)2 (0.03 mmol, 29.2 mg) was added to the filtrate, and the mixture was stirred for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 50.4 mg (76%). IR (KBr disk): 3076(w), 2924(w), 1613(m), 1574(w), 1540(vs), 1477(m), 1454(m), 1410(s), 1385(s), 1340(w), 1273(s), 1257(s), 1225(w), 1162(m), 1059(w), 1031(s), 936(m), 845(vs), 794(m), 732(m), 657(w), 639(s), 558(s), 517(w) cm−1. Anal. Calcd (%) for C160H132N16O20S4P4F36Ir4Cu2: C 43.37, H 3.00, N 5.06. Found: C 43.50, H 2.84, N 5.24. Crystals of 3a suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 3a in acetonitrile after several days. Synthesis of 3b. A mixture of [(Cp*2Rh2(μ-DHNA)Cl2] (0.03 mmol, 25.1 mg) and AgOTf (0.12 mmol, 30.8 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Cu(pyterpy)2](PF6)2 (0.03 mmol, 29.2 mg) was added to the filtrate, and the mixture was stirred for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 35.0 mg (57%). IR (KBr disk): 3072(w), 2974(w), 2924(w), 1610(m), 1574(w), 1541(vs), 1477(m), 1452(m), 1400(s), 1379(s), 1334(w), 1258(s), 1223(w), 1158(m), 1056(w), 1030(s), 934(m), 843(vs), 793(m), 732(m), 657(w), 638(s), 557(s), 516(w) cm−1. Anal. Calcd (%) for

were observed due to the addition of AgSbF6 (see Figure S1). The much larger SbF6− ions favored the formation of hexanuclear heterometallic macrocycles. It was further proved by single-crystal X-ray diffraction that complex 1a′ has a boxlike structure, as expected.

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CONCLUSIONS In summary, a series of novel [4+2] hexanuclear heterometallic macrocycles with a box-like structure were synthesized via a metalloligand approach with [M(pyterpy)2]2+ (M = Zn, Ni, and Cu) and half-sandwich organometallic [(Cp*2M2(μ-DHNA)Cl2] (M = Ir and Rh) units, and their templating effects of metals and anions were studied. The results illustrate that the tetradentate 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine has the potential to be used as a building block for the formation of heterometallic macrocycles through the pendant pyridine rings. Moreover, based on the different combinations of metals, they have the ability to encapsulate guest anions within the cavities.

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EXPERIMENTAL SECTION

General Considerations. All reactions and manipulations were carried out under a nitrogen atmosphere by using standard Schlenk techniques. MeOH, CH2Cl2, and CH3CN solvents were purified by standard methods prior to use. [Cp*MCl2]2 (M = Ir and Rh), [(Cp*2M2(μ-DHNA)Cl2] (M = Ir and Rh), pyterpy, [Zn(pyterpy)2](NO3)2, [Ni(pyterpy)2](NO3)2, and [Cu(pyterpy)2](PF6)2 were all prepared according to the literature methods.4,17,27−30 Synthesis of 1a. A mixture of [(Cp*2Ir2(μ-DHNA)Cl2] (0.03 mmol, 30.4 mg) and AgOTf (0.12 mmol, 30.8 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Zn(pyterpy)2](NO3)2 (0.03 mmol, 24.3 mg) was added to the filtrate, and the mixture was stirred for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 41 mg (61%). 1H NMR (400 MHz, CD3OD, ppm): 8.96−9.00 (m, 16H; H1, H3), 8.82−8.85 (q, 8H4), 8.54 (d, J = 8 Hz, 8H1′), 8.19 (d, J = 6 Hz, 8H2), 8.06−8.08 (q, 8H2′), 7.67−7.73 (m, 16H; H5, H7), 6.87−6.90 (m, 8H6), 1.77 (s, 60H; Cp*). IR (KBr disk): 3074(w), 2927(w), 1613(m), 1575(w), 1541(vs), 1478(m), 1453(m), 1410(s), 1384(vs), 1340(w), 1277(vs), 1259(vs), 1223(w), 1157(m), 1080(w), 1059(w), 1030(vs), 936(m), 834(w), 795(m), 733(m), 658(w), 639(s), 574(w), 517(w) cm−1. Anal. Calcd (%) for C164H132N16O32S8F24Ir4Zn2: C 44.26, H 2.99, N 5.03. Found: C 44.50, H 2.85, N 5.36. Crystals of 1a suitable for an Xray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 1a in acetonitrile after several days. Synthesis of 1a′. A mixture of [(Cp*2Ir2(μ-DHNA)Cl2] (0.03 mmol, 30.4 mg) and AgSbF6 (0.12 mmol, 41.2 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Zn(pyterpy)2](NO3)2 (0.03 mmol, 24.3 mg) was added to the filtrate, and the mixture was stirred for 24 h. Then, the solution was concentrated to give a dark red solid, which was washed by diethyl ether and dried under vacuum. Yield: 25.6 mg (33%). 1H NMR (400 MHz, CD3OD, ppm): 8.95−8.98 (m, 16H; H1, H3), 8.81−8.84 (q, 8H4), 8.50 (d, J = 8 Hz, 8H1′), 8.16 (d, J = 6.8 Hz, 8H2), 8.05−8.07 (q, 8H2′), 7.66−7.71 (m, 16H; H5, H7), 6.87−6.90 (m, 8H6), 1.77 (s, 60H; Cp*). IR (KBr disk): 3076(w), 2921(w), 1613(m), 1575(w), 1540(vs), 1477(m), 1453(m), 1411(s), 1386(vs), 1340(w), 1303(w), 1271(w), 1248(vs), 1226(w), 1164(m), 1077(w), 1058(w), 1015(m), 936(m), 832(w), 794(m), 732(m), 658(vs), 513(w) cm−1. Anal. Calcd (%) for C156H132N16O8Sb8F48Ir4Zn2: C 36.42, H 2.59, N 4.36. Found: C 36.52, H 2.71, N 4.31. Crystals of 1a′ suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 1a′ in acetonitrile after several days. Synthesis of 1b. A mixture of [(Cp*2Rh2(μ-DHNA)Cl2] (0.03 mmol, 25.1 mg) and AgOTf (0.12 mmol, 30.8 mg) in MeOH (10 mL) was stirred at room temperature for 5 h. After filtration to remove AgCl, [Zn(pyterpy)2](NO3)2 (0.03 mmol, 24.3 mg) was added to the 1288

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Article

Crystal data for 2a. C164H132F24Ir4N16Ni2O32S8, Mr = 4437.56, T = 173(2) K, monoclinic space group P2(1)/c, a = 26.365(5) Å, b = 15.193(3) Å, c = 23.581(5) Å, α = 90°, β = 109.085(3)°, γ = 90°, V = 8926(3) Å3, Z = 2, ρcalcd = 1.651 g cm−3. A total of 62 318 reflections, of which 20 352 were independent (Rint = 0.0716). The structure was refined to final R1 = 0.0679 [I > 2σ(I)], wR2 = 0.1935 for all data, GOF = 1.011, and residual electron density max./min. = 3.835 and −1.771 e Å−3. Crystal data for 2b. C164H132N16O32S8F24Rh4Ni2·4CH3OH·2Et2O· 4H2O, Mr = 4428.87, T = 173(2) K, monoclinic space group P2(1)/c, a = 16.164(2) Å, b = 28.838(4) Å, c = 20.845(3) Å, α = 90°, β = 102.916(2)°, γ = 90°, V = 9471(2) Å3, Z = 2, ρcalcd = 1.553 g cm−3. A total of 54 997 reflections, of which 16 600 were independent (Rint = 0.0497). The structure was refined to final R1 = 0.1246 [I > 2σ(I)], wR2 = 0.3301 for all data, GOF = 1.057, and residual electron density max./min. = 2.367 and −1.964 e Å−3. Crystal data for 3a. C160H132N16O20S4P4F36Ir4Cu2·4Et2O, Mr = 4727.30, T = 173(2) K, monoclinic space group P2(1)/c, a = 16.1245(18) Å, b = 29.342(3) Å, c = 20.812(2) Å, α = 90°, β = 104.224(2)°, γ = 90°, V = 9544.7(19) Å3, Z = 2, ρcalcd = 1.645 g cm−3. A total of 56 481 reflections, of which 16 756 were independent (Rint = 0.0428). The structure was refined to final R1 = 0.0655 [I > 2σ(I)], wR2 = 0.2007 for all data, GOF = 1.071, and residual electron density max./min. = 6.183 and −1.824 e Å−3. Crystal data for 3b. C160H132N16O20S4P4F36Rh4Cu2·2CH3CN· 4Et2O, Mr = 4452.23, T = 173(2) K, monoclinic space group P2(1)/c, a = 16.1031(4) Å, b = 29.3824(7) Å, c = 20.8407(5) Å, α = 90°, β = 104.0760(10)°, γ = 90°, V = 9564.7(4) Å3, Z = 2, ρcalcd = 1.546 g cm−3. A total of 46 244 reflections, of which 16 243 were independent (Rint = 0.0609). The structure was refined to final R1 = 0.0905 [I > 2σ(I)], wR2 = 0.2690 for all data, GOF = 1.055, and residual electron density max./min. = 3.275 and −0.634 e Å−3. Crystal data for 4b. C60H58N10O6Cl4Rh2Ni·CH3OH·2H2O, Mr = 1489.57, T = 173(2) K, monoclinic space group C2/c, a = 53.4454(9) Å, b = 8.8419(2) Å, c = 33.7700(6) Å, α = 90°, β = 112.0290(10)°, γ = 90°, V = 14793.3(5) Å3, Z = 8, ρcalcd = 1.338 g cm−3. A total of 32 720 reflections, of which 10 090 were independent (Rint = 0.0416). The structure was refined to final R1 = 0.0506 [I > 2σ(I)], wR2 = 0.1489 for all data, GOF = 1.066, and residual electron density max./min. = 0.890 and −0.637 e Å−3.

C160H132N16O20S4P4F36Rh4Cu2: C 47.17, H 3.27, N 5.50. Found: C 47.02, H 3.08, N 5.24. Crystals of 3b suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of 3b in acetonitrile after several days. Synthesis of 4a. A mixture of [Cp*IrCl2]2 (0.03 mmol, 23.9 mg) and Ni(pyterpy)2(NO3)2 (0.03 mmol, 24.1 mg) in a 1:1 mixture of MeOH/CH3CN (5 mL/5 mL) was stirred at room temperature for 12 h, and a clear yellow solution was obtained. Crystals of 4a suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 4a in MeOH/CH3CN after several days. Yield: 22.5 mg (47%). IR (KBr disk): 3061(w), 2962(w), 2916(w), 1605(s), 1571(w), 1541(w), 1473(s), 1409(s), 1384(vs), 1359(vs), 1337(vs), 1247(w), 1160(w), 1079(w), 1015(m), 829(m), 791(m), 750(w), 658(w), 514(w) cm−1. Anal. Calcd (%) for C60H58N10O6Cl4Ir2Ni: C 45.04, H 3.65, N 8.75. Found: C 45.18, H 3.58, N 8.64. Synthesis of 4b. A mixture of [Cp*RhCl2]2 (0.03 mmol, 18.6 mg) and Ni(pyterpy)2(NO3)2 (0.03 mmol, 24.1 mg) in a 1:1 mixture of MeOH/CH2Cl2 (5 mL/5 mL) was stirred at room temperature for 12 h, and a clear red solution was obtained. Crystals of 4b suitable for an X-ray diffraction study were obtained by slow diffusion of diethyl ether into a solution of complex 4b in MeOH/CH2Cl2 after several days. Yield: 36.4 mg (85%). IR (KBr disk): 3060(w), 2911(w), 1605(s), 1571(w), 1474(s), 1409(s), 1384(vs), 1248(w), 1160(w), 1078(w), 1016(m), 832(w), 794(m), 750(w), 657(w), 514(w) cm−1. Anal. Calcd (%) for C60H58N10O6Cl4Rh2Ni: C 50.70, H 4.11, N 9.85. Found: C 50.53, H 4.28, N 9.64. X-ray Crystal Structure Determinations. All the determinations of unit cell and intersity data were performed with graphitemonochromated Mo Kα radiation (λ = 0.71073 Å) and expecially Cu radiation (λ = 1.541 84 Å) for complexes 3b and 4b, respectively. All the data were collected at 173(2) K using the ω scan technique. These structures were solved by direct methods, using Fourier techniques, and refined on F2 by a full-matrix least-squares method. All the calculations were carried out with the SHELXTL program.31 Data of complexes 3b and 4b were collected by Cu Kα radiation, which results in the completeness and _diffrn_measured_fraction_theta_full being low. In the asymmetric unit of all data, the SQUEEZE algorithm was used to omit the disordered anions and/or solvents. Because the given molecular formula and weight contain these disordered fragments, it is quite different from such values calculated by software. The high residual peaks of almost all complexes may be thought of as tail effects because they were found near the metal centers. A summary of the crystallographic data and selected experimental information are given in the following. Crystal data for 1a. C164H132N16O32S8F24Ir4Zn2·2CH3OH, Mr = 4514.96, T = 173(2) K, monoclinic space group P2(1)/c, a = 26.557(4) Å, b = 15.194(2) Å, c = 23.626(3) Å, α = 90°, β = 108.783(2)°, γ = 90°, V = 9026(2) Å3, Z = 2, ρcalcd = 1.661 g cm−3. A total of 64 221 reflections, of which 20 654 were independent (Rint = 0.0757). The structure was refined to final R1 = 0.0608 [I > 2σ(I)], wR2 = 0.1791 for all data, GOF = 0.969, and residual electron density max./min. = 3.407 and −1.579 e Å−3. Crystal data for 1a′. C156H132N16O8Sb8F48Ir4Zn2·4CH3CN·2Et2O, Mr = 5456.98, T = 173(2) K, monoclinic space group P2(1)/c, a = 17.5422(18) Å, b = 26.9683(2) Å, c = 25.609(3) Å, α = 90°, β = 108.671(2)°, γ = 90°, V = 114792 (2) Å3, Z = 2, ρcalcd = 1.778 g cm−3. A total of 83 628 reflections, of which 26 423 were independent (Rint = 0.0880). The structure was refined to final R1 = 0.1152 [I > 2σ(I)], wR2 = 0.3425 for all data, GOF =1.071, and residual electron density max./min. = 9.267 and −2.857 e Å−3. Crystal data for 1b. C164H132N16O32S8F24Rh4Zn2·4CH3OH·2Et2O· 4H2O, Mr = 4442.19, T = 173(2) K, monoclinic space group P2(1)/c, a = 16.1642(18) Å, b = 29.018(3) Å, c = 20.852(2) Å, α = 90°, β = 102.507(2)°, γ = 90°, V = 9548.8(18) Å3, Z = 2, ρcalcd = 1.545g cm−3. A total of 56 233 reflections, of which 16 744 were independent (Rint = 0.0313). The structure was refined to final R1 = 0.1131 [I > 2σ(I)], wR2 = 0.2889 for all data, GOF = 1.086, and residual electron density max./min. = 3.001 and −1.730 e Å−3.

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ASSOCIATED CONTENT

S Supporting Information *

Figures, tables, and CIF files giving details for X-ray data collection and the refinements of complexes 1a−3b and 4b and the 1H NMR spectra (CD3OD) of complexes 1a, 1b, and 1a′. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Tel: +86-21-65643776. Fax: +86-21-65641740. E-mail: gxjin@ fudan.edu.cn. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS

This work was supported by the National Science Foundation of China (91122017, 21374019), the Shanghai Science and Technology Committee (13JC1400600, 13DZ2275200), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT1117). 1289

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(29) Ding, Y.; Wang, F.; Ku, Z.-J.; Wang, L.-S.; Zhou, H.-B. J. Struct. Chem. 2009, 50 (6), 1212. (30) (a) Bennett, M. A.; Huang, T.-N.; Matheeson, T. W.; Smith, A. K. Inorg. Synth. 1982, 21, 74. (b) White, C.; Yates, A.; Maitlis, P. M. Inorg. Synth. 1992, 29, 228. (31) Sheldrick, G. M. SHELXL-97; Universität Göttingen: Germany, 1997.

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