Structural evolution and magnetic properties of a series of coordination polymers featuring dinuclear secondary-building units and adamantane-dicarboxylato ligands

Polyhedron 52 (2013) 1159–1168

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Structural evolution and magnetic properties of a series of coordination polymers featuring dinuclear secondary-building units and adamantane-dicarboxylato ligands Yan-Zhen Zheng a,b,⇑, Zhiping Zheng a,c, Ming-Liang Tong b, Xiao-Ming Chen b a b c

Centre for Applied Chemical Research, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry & Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ 85721, USA

a r t i c l e

i n f o

Article history: Available online 28 June 2012 Dedicated to Alfred Werner on the 100th Anniversary of his Nobel prize in Chemistry in 1913. Keywords: Coordination polymer Adamantane dicarboxylate Dinuclear Magnetic property

a b s t r a c t A series of coordination polymers, [Cu2(1,3-adc)2(H2O)2] (1), [Cu2(1,3-ada)2(H2O)2] (2), [M2(1,3-ada)2 (4,40 -bpy)] M = Cu (3), Co (4), [Ni2(1,3-ada)2(4,40 -bpy)2] (5), [Mn2(1,3-ada)2(4,40 -bpy)2](1,3-adaH2) (H2O)0.5 (6), and [Ni2(1,3-adc)2(4,40 -bpy)] (7) (1,3-adcH2 = 1,3-adamantanedicarboxylic acid, 1,3adaH2 = 1,3-adamantanediacetic acid, 4,40 -bpy = 4,40 -bipyridine) were synthesized under hydrothermal conditions. Single-crystal X-ray diffraction studies revealed that a majority of these complexes feature a laminated structure based on the cross-linking of dinuclear metal units and organic connectors. Both compounds 1 and 2 feature a CuII2 paddle-wheel secondary-building unit that can be linked by the rigid 1,3-adc or flexible 1,3-ada, forming a linear chain structure in 1 and a rhomboidal net structure in 2. Substituting the apical aqua ligands of 2 for 4,40 -bpy afforded a (4,4) square layer of 3. Replacing CuII for CoII yielded isostructural compound 4. The uses of NiII and MnII ions in the synthesis of compounds 5 and 6 significantly altered the rhomboidal layer into a different kind of layered structure that features double-helix metal-dicarboxylate chains circumambulating the central 4,40 -bpy pillar. On the other hand, the use of rigid 1,3-adc in replacement of 1,3-ada led to the formation of the 2-fold interpenetrated layer of 7. Magnetic measurements indicated that there exist weak antiferromagnetic interactions in the dinuclear units of compound 5. Ó 2012 Elsevier Ltd. All rights reserved.

1. Introduction The design and synthesis of molecular materials according to the principles of crystal engineering continue to enjoy much interest in recent years [1–4]. Of particular note are coordination polymers self-assembled under hydro- and solvo-thermal conditions. A great variety of compounds have been reported in the literature, many of which possessing not only complex and aesthetically pleasing structures [5–10] but also interesting and potentially useful properties [11–15]. Inspired by the work of Yaghi et al. who constructed metal–organic frameworks (MOFs) [11b] equipped with coordinatively unsaturated metal sites using 1,3,5,7-adamantane-tetracarboxylate as ligand, we have recently explored the use of two related ligands, 1,3-adamantanediacetate(1,3-ada) and 1,3-adamantanedicarboxylate(1,3-adc) (Fig. 1a and b), in a similar capacity. With the use of 4,40 -bipyridine(4,40 -bpy) as a potential auxiliary pillar ligand, we

⇑ Corresponding author at: Centre for Applied Chemical Research, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710054, China. E-mail address: [email protected] (Y.-Z. Zheng). 0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.poly.2012.06.051

hoped to prepare porous materials that may be useful for gas storage or catalysis. Our work, however, produced seven non-porous coordination polymers: [Cu2(1,3-adc)2(H2O)2] (1), [Cu2(1,3-ada)2(H2O)2] (2), [M2(1,3-ada)2(4,40 -bpy)] M = Cu (3), Co (4), [Ni2(1,3-ada)2(4,40 bpy)2] (5), [Mn2(1,3-ada)2(4,40 -bpy)2](1,3-adaH2)(H2O)0.5 (6), and [Ni2(1,3-adc)2(4,40 -bpy)] (7), each featuring dinuclear secondary building units (SBUs), the adamantine-carboxylate ligands, and 4,40 -bpy (if used in the synthesis). One of these compounds, 5, has been shown to possess antiferromagnetic exchange–coupling interactions within the dinuclear unit. 2. Experimental 2.1. Materials and instrumentation The reagents and solvents were commercially available and used as received. The C, H, and N microanalyses were carried out with an Elementar Vario-EL CHNS elemental analyzer. The FT-IR spectra were recorded using KBr pellets using a Bio-Rad FTS-7 spectrometer. Magnetic susceptibility measurements were

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Y.-Z. Zheng et al. / Polyhedron 52 (2013) 1159–1168

O

OH

2.2. Synthesis 2.2.1. [Cu2(1,3-adc)2(H2O)2] 1 A mixture of Cu(NO3)24H2O (0.242 g, 1.0 mmol), 1,3-adcH2 (0.112 g, 0.5 mmol), NaOH (0.04 g, 1.0 mmol) in de-ionized water (15 mL) was stirred for 15 min in air. The resulting mixture was sealed in a 25-mL Teflon-lined reactor, heated at 180 °C for 3 days and then cooled to room temperature at a rate of 5 °C h1. The crude product was isolated as green plate-shaped crystals, washed with water and ethanol, and dried under vacuo (yield 35% based on Cu). Elemental analysis (%): C12H15O5Cu (302.78): calc. C, 47.60; H, 4.99. Found: C, 47.36; H, 5.08. IR (KBr, cm1): m = 3440s, 2930s, 2857m, 1660w, 1587s, 1499w, 1465w, 1394s 1341w, 1313m, 1260w, 1119w, 998w, 880w, 824w, 775w, 748w, 696m, 677w, 617w, 507m, 437m.

O OH Fig. 1a. Structure of the 1,3-adcH2 ligand.

O OH O

2.2.2. [Cu2(1,3-ada)2(H2O)2] 2 Compound 2 was prepared analogously with 1,3-adaH2 (0.126 g, 0.5 mmol) replacing 1,3-adcH2 in the synthesis of 1. The product was isolated as plate-like green crystals in 75% yield (based on Cu). Elemental analysis (%): C14H20O5Cu (331.69): calc. C, 50.67; H, 6.07. Found: C, 50.61; H, 6.09. IR (KBr, cm1): m = 3645m, 3296m, 3204w, 2904s, 2847m 2677w, 1602s, 1449m, 1408s, 1363m, 1342w, 1316w, 1277w, 1239w, 1170w, 1151w, 1049w, 987w, 792w, 757w, 718w, 680m, 542w, 457w.

OH Fig. 1b. Structure of the 1,3-adaH2 ligand.

O

O

O O O

M

M

O O

O

2.2.3. [Cu2(1,3-ada)2(4,40 -bpy)] 3 A mixture of Cu(NO3)24H2O (0.242 g, 1.0 mmol), 1,3-adaH2 (0.126 g, 0.5 mmol), 4,40 -bpy (0.078 g, 0.5 mmol), NaOH (0.04 g, 1.0 mmol) in de-ionized water (15 mL) was stirred for 15 min in air. It was then sealed in a 25-mL Teflon-lined reactor, heated at 180 °C for 3 days, and then cooled to room temperature at a rate of 5 °C h1. The crude crystalline product was collected by filtration, washed with water and ethanol, and dried in vacuo (yield 85% based on Cu). Elemental analysis (%): C19H22O4NCu (391.92): calc. C, 58.23; H, 5.66; N.3.57. Found: C, 58.19; H, 5.68; N.3.51. IR (KBr, cm1): m = 3430w, 3050w, 2896s, 2845m, 1969w, 1602s, 1541m, 1413s, 1391m, 1361w, 1342w, 1310m, 1245w, 1220m, 1175w, 1136w, 1106w, 1077w, 1043w, 1007w, 865w, 824m, 758w, 733w, 712w, 679m, 629w, 593w, 571w, 521w and 462w.

Fig. 1c. The four l-carboxylate dinuclear SUB in 1–4 and 7.

O

O

O

M

O O

M

O

O

O

Fig. 1d. The four l-carboxylate dinuclear SUB in 5 and 6.

2.2.4. [Co2(1,3-ada)2(4,40 -bpy)] 4 Compound 4 was prepared using a procedure similar to the synthesis of 3 with the use of CoCl26H2O (0.238 g, 1.0 mmol) in place of Cu(NO3)24H2O. The product was isolated as purple plate-shaped

performed with poly-crystalline samples on a Quantum Design MPMS-XL7 SQUID, and the data were corrected for the diamagnetic contribution calculated using Pascal constants. Table 1 Crystallographic data for 1, 2, 3, 4, 5, 6 and 7. Complex

1

2

3

4

5

6

7

Formula Formula weight T (K) Space group

C24H32Cu2O10 607.60 293(2) C2/m (No. 12) 19.907(6) 8.641(3) 6.947(2) 90 93.33(8) 90 1193.0(6) 2 1.686 1.841 0.0689 0.1884

C28H40Cu2O10 663.38 293(2) P21/n (No. 14) 11.872(1) 7.379(6) 16.728(1) 90 102.16(2) 90 1432.5(2) 2 1.529 1.540 0.0421 0.1120

C38H44Cu2N2O8 783.84 293(2) C2/c (No. 15) 22.414(1) 14.044(8) 11.270(7) 90 113.72(1) 90 3247.9(3) 4 1.603 1.517 0.0333 0.0888

C38H44Co2N2O8 774.62 293(2) C2/c (No.15) 22.624(2) 13.906(1) 11.289(1) 90 113.41(2) 90 3259.2(5) 4 1.579 1.078 0.0468 0.1065

C48H52N4Ni2O8 930.36 293(2) P21/c (No.14) 13.40(1) 11.317(9) 15.13(1) 90 107.59(2) 90 2188(3) 2 1.412 0.920 0.0629 0.1832

C62H73Mn2N4O12.5 1184.12 293(2)  P1 (No. 2) 11.640(5) 15.256(6) 17.666(7) 109.28(6) 107.94(6) 93.88(7) 2767(2) 1 1.429 0.528 0.1013 0.3087

C34H36Ni2N2O8 718.07 293(2) Pmma (No. 51) 28.135(3) 8.546(3) 14.020(1) 90 90 90 3371.0(5) 4 1.415 1.169 0.1139 0.2583

a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dcalc. (g cm3) l (mm1) R1 [I  2r(I)]a wR2 (all data)b a b

R1 = Fo  Fc/Fo. wR2 = [w(Fo2  Fc2)2/w(Fo2)2]1/2.

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Y.-Z. Zheng et al. / Polyhedron 52 (2013) 1159–1168 Table 2 Selected bond lengths (Å) and angles (o). 1 Cu(1)  Cu(1a) Cu(1)–O(2a) Cu(1)–O(2b) Cu(1)–O(1) Cu(1)–O(1c) Cu(1)–O(1w) O(2a)–Cu(1)–O(2b) O(2a)–Cu(1)–O(1) O(2b)–Cu(1)–O(1) O(2a)–Cu(1)–O(1c)

2.582(2) 1.965(5) 1.965(5) 1.988(5) 1.988(5) 2.104(7) 92.6(4) 169.3(2) 88.0(2) 88.0(2)

O(1)–Cu(1)–O(1c) O(2a)–Cu(1)–O(1w) O(2b)–Cu(1)–O(1w) O(1)–Cu(1)–O(1w) O(1c)–Cu(1)–O(1w) O(2a)–Cu(1)–Cu(1a) O(2b)–Cu(1)–Cu(1a) O(1)–Cu(1)–Cu(1a) O(1c)–Cu(1)–Cu(1a) O(1w)–Cu(1)–Cu(1a)

89.4(3) 97.6(2) 97.6(2) 92.9(2) 92.9(2) 85.7(2) 85.7(2) 83.7(2) 83.7(2) 175.2(2)

2 Cu1  Cu(1a) Cu(1)–O(1) Cu(1)–O(2a) Cu(1)–O(3b) Cu(1)–O(4c) Cu(1)–O(1w) O(2a)–Cu(1)–O(3b) O(2a)–Cu(1)–O(1) O(3b)–Cu(1)–O(1) O(2b)–Cu(1)–O(4c) O(3b)–Cu(1)–O(4c)

2.5976(6) 1.966(2) 1.943(2) 1.962(2) 1.991(2) 2.175(2) 88.61(8) 169.43(8) 91.02(8) 88.73(8) 168.93(7)

O(2a)–Cu(1)–O(3b) O(1)–Cu(1)–O(4c) O(2a)–Cu(1)–O(1w) O(3b)–Cu(1)–O(1w) O(1)–Cu(1)–O(1w) O(4c)–Cu(1)–O(1w) O(2a)–Cu(1)–Cu(1a) O(3b)–Cu(1)–Cu(1a) O(1)–Cu(1)–Cu(1a) O(4c)–Cu(1)–Cu(1a) O(1w)–Cu(1)–Cu(1a)

88.61(8) 89.63(8) 104.94(8) 97.09(8) 85.58(9) 93.97(8) 87.80(6) 87.46(6) 81.64(6) 81.70(5) 166.51(6)

3 Cu(1)  Cu(2) Cu(1)–O(1) Cu(1)–O(1a) Cu(1)–O(4b) Cu(1)–O(4c) Cu(1)–N(1) Cu(2)–O(3b) Cu(2)–O(3c) Cu(2)–O(2) Cu(2)–O(2a) Cu(2)–N(2d) O(1a)–Cu(1)–O(1) O(1a)–Cu(1)–O(4b) O(1)–Cu(1)–O(4b) O(4b)–Cu(1)–O(4c)

2.6633(5) 1.946(2) 1.946(2) 2.068(2) 2.068(2) 2.171(2) 1.926(2) 1.926(2) 2.024(1) 2.024(1) 2.153(2) 176.37(8) 90.25(7) 89.08(7) 158.90(8)

O(1)–Cu(1)–N(1) O(4b)–Cu(1)–N(1) O(1)–Cu(1)–Cu(2) O(4b)–Cu(1)–Cu(2) N(1)–Cu(1)–Cu(2) O(3b)–Cu(2)–O(3c) O(3b)–Cu(2)–O(2) O(3c)–Cu(2)–O(2) O(2)–Cu(2)–O(2a) O(3b)–Cu(2)–N(2d) O(2)–Cu(2)–N(2d) O(3b)–Cu(2)–Cu(1) O(2)–Cu(2)–Cu(1) N(2d)–Cu(2)–Cu(1)

91.82(4) 100.55(4) 88.18(4) 79.45(4) 180.0 175.59(9) 88.64(6) 90.51(7) 157.94(9) 92.21(4) 101.03(4) 87.79(4) 78.97(4) 180.0

4 Co(1)  Co(2) Co(1)–O(1a) Co(1)–O(4b) Co(1)–O(4c) Co(1)–N(1) Co(2)–O(3b) Co(2)–O(3c) Co(2)–O(2) Co(2)–O(2a) Co(2)–N(2d) O(1a)–Co(1)–O(4b) O(1)–Co(1)–O(4b) N(1)–Co(1)–O(4c)

2.6989(7) 2.023(2) 2.105(2) 2.105(2) 2.082(3) 1.997(2) 1.997(2) 2.059(2) 2.059(2) 2.067(3) 88.94(8) 89.80(8) 98.99(5)

O(4b)–Co(1)–O(4c) O(1)–Co(1)–Co(2) N(1)–Co(1)–Co(2) O(4b)–Co(1)–Co(2) O(3b)–Co(2)–O(3c) O(3b)–Co(2)–O(2) O(3c)–Co(2)–O(2) O(2)–Co(2)–O(2a) O(3b)–Co(2)–N(2d) O(2)–Co(2)–N(2d) O(3b)–Co(2)–Co(1) O(2)–Co(2)–Co(1) N(2d)–Co(2)–Co(1)

162.0(1) 85.96(5) 180.0 81.01(5) 170.3(1) 90.18(8) 88.16(8) 160.2(1) 94.85(5) 99.89(5) 85.15(5) 80.11(5) 180.0

5 Ni(1)  Ni(1d) Ni(1)–O(4a) Ni(1)–O(3b) Ni(1)–N(1) Ni(1)–N(2c) Ni(1)–O(1) Ni(1)–O(2) O(4a)–Ni(1)–O(3b) O(4a)–Ni(1)–N(1) O(3b)–Ni(1)–N(1) O(4a)–Ni(1)–N(2c)

4.152 2.020(5) 2.021(4) 2.093(5) 2.109(5) 2.131(5) 2.147(5) 114.1(2) 91.9(2) 93.9(2) 87.1(2)

O(3b)–Ni(1)–N(2c) N(1)–Ni(1)–N(2c) O(4a)–Ni(1)–O(1) O(3b)–Ni(1)–O(1) N(1)–Ni(1)–O(1) N(2c)–Ni(1)–O(1) O(4a)–Ni(1)–O(2) O(3b)–Ni(1)–O(2) N(1)–Ni(1)–O(2) N(2c)–Ni(1)–O(2) O(1)–Ni(1)–O(2)

86.9(2) 178.9(2) 153.4(2) 92.1(2) 90.6(2) 90.1(2) 91.4(2) 153.9(2) 90.5(2) 89.1(2) 62.1(2)

6 Mn(1)  Mn(1a) Mn(1)–O(2a) Mn(1)–O(1) Mn(1)–O(8b) Mn(1)–N(1) Mn(1)–N(2b) Mn(1)–O(7b)

4.060 2.075(6) 2.094(6) 2.248(6) 2.252(7) 2.278(7) 2.310(7)

N(1)–Mn(1)–N(2b) O(2a)–Mn(1)–O(7b) O(1)–Mn(1)–O(7b) O(8b)–Mn(1)–O(7b) N(1)–Mn(1)–O(7b) N(2b)–Mn(1)–O(7b) O(6c)–Mn(2)–O(5)

176.6(3) 91.4(2) 146.0(2) 57.2(2) 90.4(2) 89.1(2) 120.7(3)

Mn(2)–O(6c) Mn(2)–O(5) Mn(2)–O(4) Mn(2)–N(3) Mn(2)–N(4b) Mn(2)–O(3) O(2a)–Mn(1)–O(1) O(2a)–Mn(1)–O(8b) O(1)–Mn(1)–O(8b) O(2a)–Mn(1)–N(1) O(1)–Mn(1)–N(1) O(8b)–Mn(1)–N(1) O(2a)–Mn(1)–N(2b) O(1)–Mn(1)–N(2b) O(8b)–Mn(1)–N(2b)

2.083(6) 2.095(6) 2.248(6) 2.280(6) 2.284(7) 2.287(6) 122.3(3) 148.4(3) 88.9(2) 90.4(2) 93.2(2) 92.6(2) 86.3(2) 89.0(2) 89.9(2)

O(6c)–Mn(2)–O(4) O(5)–Mn(2)–O(4) O(6c)–Mn(2)–N(3) O(5)–Mn(2)–N(3) O(4)–Mn(2)–N(3) O(6c)–Mn(2)–N(4b) O(5)–Mn(2)–N(4b) O(4)–Mn(2)–N(4b) N(3)–Mn(2)–N(4b) O(6c)–Mn(2)–O(3) O(5)–Mn(2)–O(3) O(4)–Mn(2)–O(3) N(3)–Mn(2)–O(3) N(4b)–Mn(2)–O(3)

148.3(2) 89.2(2) 90.3(2) 92.0(2) 99.5(2) 86.9(2) 87.5(2) 84.1(2) 176.4(3) 93.4(2) 145.9(2) 57.3(2) 88.1(2) 94.3(2)

7 Ni(1)  Ni(2) Ni(3)  Ni(3f) Ni(1)–O(1) Ni(1)–O(1a) Ni(1)–O(1b) Ni(1)–O(1c) Ni(1)–N(2d) Ni(2)–O(2) Ni(2)–O(2b) Ni(2)–O(2c) Ni(2)–N(1) Ni(3)–O(3) Ni(3)–O(3e) Ni(3)–O(4f) Ni(3)–O(4g) Ni(3)–N(3) O(1a)–Ni(1)–O(1) O(1a)–Ni(1)–O(1b) O(1)–Ni(1)–O(1b) O(1a)–Ni(1)–O(1c) O(1)–Ni(1)–O(1c) O(1b)–Ni(1)–O(1c) O(1a)–Ni(1)–N(2d) O(1)–Ni(1)–N(2d) O(1b)–Ni(1)–N(2d) O(1c)–Ni(1)–N(2d) O(1a)–Ni(1)–Ni(2) O(1)–Ni(1)–Ni(2) O(1b)–Ni(1)–Ni(2) O(1c)–Ni(1)–Ni(2) N(2d)–Ni(1)–Ni(2)

2.610(3) 2.625(3) 1.974(6) 1.974(6) 1.974(6) 1.974(6) 2.15(1) 1.954(6) 1.954(6) 1.954(6) 2.18(1) 1.966(6) 1.966(6) 1.970(6) 1.970(6) 2.19(1) 89.8(4) 88.9(4) 167.9(4) 167.9(4) 88.9(4) 89.8(4) 96.1(2) 96.1(2) 96.1(2) 96.1(2) 84.0(2) 84.0(2) 84.0(2) 84.0(2) 180.00(2)

O(2)–Ni(2)–O(2a) O(2)–Ni(2)–O(2b) O(2a)–Ni(2)–O(2b) O(2)–Ni(2)–O(2c) O(2a)–Ni(2)–O(2c) O(2b)–Ni(2)–O(2c) O(2)–Ni(2)–N(1) O(2a)–Ni(2)–N(1) O(2b)–Ni(2)–N(1) O(2c)–Ni(2)–N(1) O(2)–Ni(2)–Ni(1) O(2a)–Ni(2)–Ni(1) O(2b)–Ni(2)–Ni(1) O(2c)–Ni(2)–Ni(1) N(1)–Ni(2)–Ni(1) O(3)–Ni(3)–O(3e) O(3)–Ni(3)–O(4f) O(3e)–Ni(3)–O(4f) O(3)–Ni(3)–O(4g) O(3e)–Ni(3)–O(4g) O(4f)–Ni(3)–O(4g) O(3)–Ni(3)–N(3) O(3e)–Ni(3)–N(3) O(4f)–Ni(3)–N(3) O(4g)–Ni(3)–N(3) O(3)–Ni(3)–Ni(3f) O(3e)–Ni(3)–Ni(3f) O(4f)–Ni(3)–Ni(3f) O(4g)–Ni(3)–Ni(3f) N(3)–Ni(3)–Ni(3f)

90.2(5) 167.5(4) 88.4(5) 88.4(5) 167.5(4) 90.2(5) 96.2(2) 96.2(2) 96.2(2) 96.2(2) 83.8(2) 83.8(2) 83.8(2) 83.8(2) 180.00(2) 89.6(4) 167.7(3) 89.0(3) 89.0(3) 167.7(3) 89.8(4) 98.6(3) 98.6(3) 93.7(3) 93.7(3) 84.3(2) 84.3(2) 83.4(2) 83.4(2) 175.8(3)

Symmetry codes: for 1, (a) = x, y, z + 1; (b) = x, y, z + 1; (c) = x, y, z; (d) = x, y  1, z; for 2, (a) = x + 2, y + 2, z + 1; (b) = x + 1/2, y + 5/2, z + 1/2; (c) = x + 3/2, y  1/2, z + 1/2; (d) = x  1/2, y + 5/2, z  1/2; (e) = x + 3/2, y + 1/ 2, z + 1/2; for 3, (a) = 1 x, y, z + 1/2; (b) = x + 1/2, y + 1/2, z + 1; (c) = x  1/ 2, y + 1/2, z  1/2; (d) = x, y  1, z; (e) = x, y + 1, z; for 4, (a) = x, y, z + 1/2; (b) = x  1/2, y + 1/2, z  1/2; (c) = x + 1/2, y + 1/2, z + 1; (d) = x, y  1, z; (e) = x, y + 1, z; for 5, (a) = x, y + 3/2, z  1/2; (b) = x + 1, y + 1/2, z + 3/2; (c) = x, y  1, z; (d) = x + 1, y  1/2, z + 3/2; (e) = x, y + 3/2, z + 1/2; (f) = x, y + 1, z; for 6, (a) = x, y  1, z; (b) = x + 1, y, z; (c) = x  1, y, z; (d) = x  1, y, z; for 7, (a) = x + 3/2, y + 3, z; (b) = x, y + 3, z; (c) = x + 3/2, y, z; (d) = x, y, z  1; (e) = x, y + 2, z; (f) = x + 1, y + 2, z + 2; (g) = x + 1, y, z + 2; (h) = x, y, z + 1; (i) = x + 1/2, y + 2, z.

crystals in 75% yield (based on Co). Elemental analysis (%): C19H22O4NCo (386.12): calc. C, 58.92; H, 5.73; N.3.62. Found: C, 58.89; H, 5.68; N.3.66. IR (KBr, cm1): m = 3431m, 3101w, 3053w, 2894s, 2845s, 1971w, 1602s, 1539m, 1485m, 1424s, 1392m, 1362w, 1342w, 1308m, 1244w, 1220m, 1173w, 1133w, 1107w, 1079w, 1011w, 868w, 828m, 757w, 730w, 707w, 674m, 646m, 587w, 520w, 440w. 2.2.5. [Ni2(1,3-ada)2(4,40 -bpy)2] 5 Compound 5 was prepared using a procedure similar to the synthesis of 3 with NiCl26H2O (0.238 g, 1.0 mmol) in place of Cu(NO3)24H2O. The product was isolated as pale green plate-shaped crystals in 55% yield (based on Ni). Elemental analysis (%): C24H26O4N2Ni (465.17): calc. C, 61.97; H, 5.63; N.6.02. Found: C,

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61.69; H, 5.95; N.5.96. IR (KBr, cm1): m = 3639w, 3101w, 3383w, 3047w, 2894s, 2847m, 1679w, 1606s, 1548s, 1488m, 1450s, 1420s, 1359w, 1312w, 1254w, 1221w, 1151w, 1070w, 1044w, 1009w, 882w, 816m, 718w, 677w, 634m, 577w, 533w, 475w.

2.2.7. [Ni2(1,3-adc)2(4,40 -bpy)] 7 Compound 7 was prepared using a procedure similar to the synthesis of 5 with the use of 1,3-adcH2 (0.126 g, 0.5 mmol) in place of 1,3-adaH2. The product was isolated as pale green plate-shaped crystals in 45% yield (based on Ni). Elemental analysis (%): C34H36O8N2Ni (387.08): calc. C, 58.96; H, 5.73; N.3.62. Found: C, 58.82; H, 5.98; N 3.55. IR (KBr, cm1): m = 3426m, 3101w, 2939s, 2906s, 2858m, 1602s, 1535m, 1487w, 1450w, 1400s, 1339w, 1314w, 1286w, 1219m, 1227w, 1070w, 1042w, 1003w, 953w, 881w, 810m, 774w, 710m, 628w, 507m, 435w.

2.2.6. [Mn2(1,3-ada)2(4,40 -bpy)2](1,3-adaH2)(H2O)0.5 6 Compound 6 was prepared analogously with MnCl24H2O (0.198 g, 1.0 mmol) replacing Cu(NO3)24H2O in the synthesis of 3. The product was isolated as pale yellow plate-shaped crystals in 40% yield (based on Mn). Elemental analysis (%): C62H74O13N4Mn2 (1193.15): calc. C, 62.41; H, 6.25; N.4.70. Found: C, 62.45; H, 6.19; N.4.66. IR (KBr, cm1): m = 3380w, 3063w, 2899s, 2845s, 1712s, 1589s, 1549s, 1487w, 1447s, 1410s, 1360w, 1314m, 1252m, 1222m, 1150m, 1076w, 1005w, 950w, 899w, 812m, 725w, 676w, 627m, 572w, 530w, 484w.

2.3. X-ray Crystallography The single crystal reflection data of 1, 2, 3, 4, 5, 6, and 7 were collected on a Bruker Apex CCD diffractometer with the graphite-

Cu 2+

2

2 + ), 2+ (C o

L2

4 4 '- b

py

3 (4)

Cu

2+ Ni2+(Mn ), 44'-bpy

5 (6)

Cu2+

L1

Ni2+, 44'-bpy

1

7

L1 = 1,3-adc L2 = 1,3-ada

=

O O O O M

M O

O O O

=

O O O O M O M O O O

=

44'-bpy

=

Fig. 2. A general synthesis route for the seven compounds and simplified structures based on the SUB node (water molecules are omitted for clarity).

Y.-Z. Zheng et al. / Polyhedron 52 (2013) 1159–1168

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Fig. 3a. Perspective view of the coordination environments of the metal atoms with labels in 1.

Fig. 4a. Perspective view of the coordination environments of the metal atoms with labels in 2.

monochromated Mo Ka (k = 0.71073 Å) radiation at 298 K. The program SAINT [16] was used to integrate the diffraction profiles. All the structures were solved by direct methods with the SHELXS program of the SHELXTL package and refined by full-matrix least-squares methods with SHELXL (semi-empirical absorption corrections were applied with the SADABS program) [17]. Anisotropic thermal parameters were assigned to all non-hydrogen atoms. The hydrogen atoms were generated geometrically with isotropic temperature factors. Data collection parameters and structure solution details are listed in Table 1. Selected bond distances and angles are listed in Table 2. X-ray powder diffraction studies were carried using a D/max – IIIA diffractometer using Cu Ka1 (k = 1.54056 Å) radiation; the data were collected over 2h range of 4–55o.

syntheses at a lower temperature (i.e. 100 °C and 140 °C), but only non-crystalline product mixtures with unknown identities were obtained.

3. Results and discussions 3.1. Syntheses Compounds 1–7 were prepared hydrothermally in moderate to good yields (Fig. 2). For each, the molecular composition was verified by satisfactory elemental analyses and consistent with the crystallographically determined formula (see below). The purity of the bulk samples was suggested by the agreement of the experimental observed and calculated powder X-ray diffraction patters for all compounds (Fig. S1). Under hydrothermal conditions, thermodynamic products are anticipated. Indeed, layered structures characterized by high packing density were found for 2–7. Lending support to the compact structures is the unsuccessful attempts to produce porous structures by adding the commonly used ‘‘pillar ligand’’ 4,40 -bpy in the synthesis of 3–7. Suspecting that the relatively high reaction temperature may be responsible [7,18], we carried out the

3.2. Structural descriptions A majority of the compounds (1–4, 7) reported in this work feature paddle-wheel like secondary building units (SBUs) composed of a dimetallic core coordinated by four bridging carboxylate groups. Such motifs are prevalent in carboxylate complexes of Cu(II), Rh(II), and Ni(II) [7,18,19]. Though not as common, they have also been identified in a few Co(II) [15a] complexes, but to a much less extent for Mn(II) [20]. 3.2.1. [Cu2(1,3-adc)2(H2O)2] 1 Compound 1 crystallizes in monoclinic space group C2/m. As shown in Fig. 3a, each Cu atom is coordinated by four O atoms (Cu–O = 1.965(5)–1.988(5) Å) from four different l-carboxylate groups and one O atom from one aqua ligand (Cu– O = 2.104(7) Å), forming a slightly distorted square pyramid with the carboxylate Os forming the square basal plane and the aqua O occupying the vertex of the pyramid. The Cu  Cu distance within the dinuclear secondary building unit (SBU) is 2.582(2) Å, as shown in Fig. 1c. There is a crystallographic inversion center at the middle of the Cu  Cu paddle-wheel unit. The paired 1,3-adc ligands connect each SUB alternatively in one-dimension, forming a chain-like structure, as shown in Fig. 3b. 3.2.2. [Cu2(1,3-ada)2(H2O)2] 2 The coordination environment of the Cu atom in 2, shown in Fig. 4a, is similar to that of 1. The four carboxylate O (Cu–O = 1.943(2)–1.991(2) Å) and the aqua O (Cu–O = 2.175(2) Å) atoms form a distorted square-pyramid coordination geometry. The average Cu-O distance in struc-

Fig. 3b. A view of 1D rod-like chain in 1.

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Fig. 4b. A view of 2D rhomboidal net in 2.

ture 2 is 1.966 Å, which is shorter than the 1.977 Å distance in structure 1. The distance of the two adjacent copper atoms (Cu  Cu 2.5976(6) Å) in 2 is, however, slightly longer compared to that distance in 1. As a result of flexible 1,3-ada ligand interlacing the dicopper SUB, a waving rhomboidal net formed. As shown in Fig. 4b, the 1,3-ada ligands are not related by mirror symmetry, but circulate a 21 screw axis along crystallographically b-axis, in accordance with the P21/n space group [21]. 3.2.3. [Cu2(1,3-ada)2(4,40 -bpy)] 3 As compared with the structure of 2, in 3 the apical aqua ligand in the SBU of 2 is replaced by 4,40 -bpy ligand, a bridging ligand commonly used as pillar to support the formation of 3D porous structures. However, such a structure was not realized. Instead, 2D network of 3 formed as shown in Figs. 5a and b. The two Cu atoms within the dimetallic SBU are crystallographically independent but nevertheless very similar in terms of their coordination environments: Each is coordinated by four carboxylate O atoms (Cu– O = 1.926(2)–2.068(2) Å) and one N atom (Cu–N = 2.153(2)– 2.171(2) Å) of the 4,40 -bpy ligand, forming a slightly distorted square-pyramidal geometry. The Cu  Cu separation of Fig. 5b. A view of 2D square net in 3 and 4.

2.6633(5) Å is longer than its equivalent in 2. It is also interesting to note that the coordinated nitrogen of the pillar ligand 4,40 -bpy is exactly at the vertex of the pyramid (N–Cu(2)–Cu(1) = 180.0). Unlike the apical water in 2, 4,40 -bpy prevents the flexible 1,3-ada ligand from interlacing the dimetallic unit; the bridging ligand connects two adjacent SBUs, leading to a rigid (4,4) square net (Fig. 5b). 3.2.4. [Co2(1,3-ada)2(4,40 -bpy)] 4 By replacing Cu(II) salt of the synthesis of 3 with those of Co(II), Ni(II), and Mn(II), compounds 4, 5, and 6 were obtained, respectively. Compound 4 is isomorphous to 3 with the Co  Co separation of 2.6989(7) Å within the dimetallic SBU. The structure of this compound has been reported previously [22].

Fig. 5a. Perspective view of the coordination environments of the metal atoms in 3 and 4.

3.2.5. [Ni2(1,3-ada)2(4,40 -bpy)2] 5 and [Mn2(1,3-ada)2(4,40 -bpy)2](1,3adaH2)(H2O)0.5 6 Compounds 5 and 6 are structurally similar. In both 5 and 6, there are two different types of coordination modes of the carboxylates, l-bridging and chelating, as shown in Fig. 1d.

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1165

Fig. 6a. Perspective view of the coordination environments of the metal atoms with labels in 5.

Fig. 7. Perspective view of the coordination environments of the metal atoms with labels in 6.

Fig. 8a. Perspective view of the coordination environments of Ni(1) and Ni(2) in 7.

Fig. 6b. A view of double-helix chain (colored by yellow and red) surrounding the pillar ligand in 5 and 6.

In 5 each Ni atom is coordinated by two chelating O atoms (Ni– O = 2.131(5)–2.147(5) Å) from one carboxylate, two O atoms

(Ni–O = 2.020(5)–2.021(4) Å) of different bridging carboxylates, and two N atoms (Ni–N = 2.093(5)–2.109(5) Å) from different 4,40 -bpy ligands, forming a slightly distorted octahedral geometry (Fig. 6a). The distance of two adjacent NiII atoms (Ni  Ni = 4.152 Å) is much longer than the metalmetal distance of dinuclear SBUs in 1, 2, 3, 4, and 7, possibly due to the reduced number of bridging carboxylate ligands. To our surprise, the 4,40 -bpy ligands do not connect adjacent chains as found in 3 and 4. Instead, they act as a scroll axis surrounded by double-stranded helix chains of the 1,3-ada ligands, colored yellow and red as shown in Fig. 6b. Compound 6 has a structure similar to that of 5 except that there is a lattice dicarboxylate ligand in the asymmetric unit. As

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Fig. 8b. Perspective view of the coordination environments of Ni(3) in 7.

Fig. 8e. A view of 2-fold interpenetrated layer by independent networks (colored by yellow and red) in 7.

Fig. 8c. Perspective view of the layer along the a axis in 7.

shown in Fig. 7, there are two crytallographically independent metal ions, Mn1 and Mn2. Both Mn1 and Mn2 are in a pseudo-octahedral coordination geometry with two chelating O atoms (Mn– O = 2.248(6)–2.310(7) Å) from one carboxylate, two O atoms (Mn–O = 2.075(6)–2.095(6) Å) from different bridging carboxylates and two N atoms (Mn–N = 2.252(7)–2.284(7) Å) from two 4,40 -bpy ligands. The distance between adjacent Mn atoms in the SBU is 4.060 Å. A similar structure has been reported by Geng et al. before [23].

3.2.6. [Ni2(1,3-adc)2(4,40 -bpy)] 7 Compound 7 crystallizes in the orthorhombic space group Pmma. The asymmetric unit contains three Ni atoms, with two of them, Ni(1) and Ni(2), belonging to one molecule and the third one, Ni(3), in a second molecule. The two independent molecules have different crystallographic symmetry. Ni(1) and Ni(2) are in one molecule, each having a similar square-pyramid geometry (Fig. 8a); both are coordinated by four basal carboxylate O atoms (Ni–O = 1.954(6)–1.974(6) Å) and one apical N atom (Ni– N = 2.15(1)–2.18(1) Å) of the 4,40 -bpy ligand. The other molecule has a crystallographically higher symmetry because only one type of Ni atom whose coordination environment (Fig. 8b) is not much different from that of Ni(1)/Ni(2) is found. The Ni  Ni distances in both molecules are similar, at about 2.625 Å. It is of note that these two molecules form similar layers perpendicular to each other (Figs. 8c and d); the two layers are interpenetrating with each other through the channel of the (4,4) grids, as shown in Fig. 8e.

Fig. 8d. Perspective view of one layer along the c axis in 7.

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were also performed (Fig. 9b). The linear increase in the M-H plot shows an inflection point at ca. 5 T. According to Eq. (3),

3.3. Magnetic properties The plots of vT vs. T and 1/v vs. T for 5 are shown in Fig. 9a. At room temperature, the vT value is 1.24 cm3 mol1 K per Ni(II) ion. Upon cooling, it gradually decreases to a value of 1.0 cm3 mol1 K before sharply dropping to a minimum of 0.1 cm3 mol1 K at 2 K. The shape of the vT vs. T curve indicates antiferromagnetic interaction presented at lower temperature [24,25]. At the first approximation, the results of Curie–Weiss’s law from the high temperature (above 50 K) magnetic susceptibility data were applied to estimate the magnetic coupling interaction, giving rise to C = 1.28 cm3 mol1 K and h = 15.52 K. The C value corresponds to a g value of 2.26. The high value of g together with the negative h indicates significant orbital contribution, in line with the observations made for other octahedral Ni(II) complexes [26,27]. Considering the SBU of an Ni2 motif surrounded in the paddlewheel structure with each being also apically capped by a 4,40 -bpy, we used the Heisenberg Hamiltonian (Eq. (1)) to describe the lowlying electronic states of the isolated dimetallic unit:

^ ¼ 2J^S1 ^S2 þ g l ^SH H B

ð1Þ

where Sˆi is the spin operator of the Ni(II) ions and lB is the Bohr magneton. The resulting susceptibility data are given by Eq. (2),

vd ¼

2Ng 2 b2 ex þ 5e3x kB T 1 þ 3ex þ 5e3x

0.4 0.2

150

-3

0.6

100

-1

200

0.8

χ / cm mol

3

-1

χΤ / cm mol K

250

1.0

50

0.0 100

150

200

250

300

0

T/K Fig. 9a. The plots of vT vs. T and 1/v vs. T for 5. Solid lines are the fitting results of Eq. (1) and the Curie–Weiss law.

0.7

2K

0.6

M / Nμ Β

0.5 0.4 0.3 0.2 0.1 0.0 0

10

where Hc is the critical field and |zJ | is the magnetic interaction between two spins. When Hc = 5 T, |zJ0 | is estimated to be 3.9 K, which is consistent with the fitting result from the vT vs T plot, confirming that the isolated model used to fitting the vTT curve is reasonable. 4. Summary A series of coordination polymers have been prepared under hydrothermal conditions by using flexible/rigid adamantanedicarboxylate ligands in the absence and presence of bridging 4,40 -dipyridyl. A common feature of these 1D and 2D polymeric structures is the presence of dimetallic complex units as SBUs. The flexible dicarboxylate ligand favours layered structures, while its rigid equivalent tends to form 1D chain or square-net structures. The metalmetal distance within the SBU is significantly influenced by the number of the bridging carboxylate ligands with a shorter separation being associated with more such ligands. In addition, magnetic studies indicated that the syn–syn carboxylato-bridged Ni(II) complex exhibits antiferromagnetic interaction within the dimetallic unit. Acknowledgement

1.2

50

ð3Þ 0

ð2Þ

where x = 2J/kBT. Fitting the magnetic susceptibility data above 2 K gives rise to g = 2.20(1), J = 3.1(1) K and R = R[(vmT)obs  (vmT)2 2 3 . The magnetic coupling constant J calc] /[(/vmT)obs] = 2.4  10 indicates an antiferromagnetic coupling via the bridging carboxylate groups. To further understand the magnetic interactions between the Ni(II) ions, the field-dependent magnetization experiments at 2 K

0

g lB HC S ¼ 2jzJ0 jS2

20

30

40

H / KOe

50

60

70

Fig. 9b. The field-dependent magnetization of 5 at 2 K.

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