- Email: [email protected]
Hydrothermal syntheses, crystal structures and characterizations of three new copper coordination polymers
Inorganica Chimica Acta 358 (2005) 3347–3354 www.elsevier.com/locate/ica
Hydrothermal syntheses, crystal structures and characterizations of three new copper coordination polymers Yi-Hang Wen a
a,b,c
, Jian-Kai Cheng a, Yun-Long Feng b, Jian Zhang Zhao-Ji Li a, Yuan-Gen Yao a,*
a,c
,
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, PR China b Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, PR China c Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China Received 26 January 2005; received in revised form 22 April 2005; accepted 5 May 2005 Available online 15 June 2005
Abstract Three new copper complexes, [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n (1), [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O (2), and [Cu(ipH)2(4,4 0 -bipy)]n (3), have been hydrothermally synthesized by the reaction of Cu(NO3)2 Æ 3H2O with isophthalic acid (ipH2) and 4,4 0 -bipyridine (4,4 0 bipy) under different reaction conditions. Complex 1, a mixed-valence copper(I,II) complex, exhibits a 2-D interpenetrating grid framework, in which five-coordinated CuII and three-coordinated CuI environments are established. The oxidation states of center Cu atoms have been confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectra (EPR). Complex 2 features a 2-D box-like bilayer architecture, in which CuII atoms are linked by ip ligands to form a 1-D double-chain and the resulting chains are further strutted by the 4,4 0 -bipy ligands. In complex 3, two bridging 4,4 0 -bipy ligands and two terminal ipH ligands confine the CuII center in a square plane coordination geometry. The whole molecule of 3 was arranged into a 1-D linear chain structure. Additionally, the thermogravimetric analyses (TGA) for complexes 1–3 are also discussed in this paper. 2005 Elsevier B.V. All rights reserved. Keywords: Hydrothermal synthesis; Reaction condition; Coordination architecture; Mixed ligand; Copper complex
1. Introduction The design and synthesis of novel coordination architectures controlled by varying the reaction conditions (including temperature [1,2], metal-to-ligand ratio [3], pH value [4], solvents [5], and counteranions [6,7]) are of great interest in coordination chemistry. However, how to synthesize desirable architectures with useful properties is still a major challenge to chemists in this research field [8–10]. Recently, hydrothermal synthesis has *
Corresponding author. Tel.: +86 591 83711523; fax: +86 591 83714946. E-mail address: [email protected] (Y.-G. Yao). 0020-1693/$ - see front matter 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2005.05.004
gained impressive progress [11–13], of which the increasing interest derives from its advantages in terms of high reactivity of reactants, easy control of solution or interface reactions, formation of metastable and unique condensed phases, less air pollution, and low energy consumption [14]. Hydrothermal technique provides a powerful tool for the construction of such kind of materials containing unique structures and special properties. The mechanism of hydrothermal reactions is shifting from the kinetic control to the thermodynamic control, making the molecular structures obtained by this method more difficult to expect compared to those obtained by the conventional solution method [15]. Nevertheless, if the reaction conditions, of which temperature and
3348
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
metal-to-ligand ratio of reaction conditions are vital, are properly controlled, it is possible to construct new materials with desired useful properties. The main strategy widely used in this area is the building-block approach. Hence, our studies are mainly focused on selecting suitable multidentate organic ligands or mixed ligands under appropriate conditions to construct novel coordination architectures [16–20]. As known, benzoic multicarboxylate ligands such as 1,2,4,5-benzenetetracarboxylic acid [21], 1,3,5-benzenetricarboxylic acid [22], and 1,2 (1,3 or 1, 4)-benzenedicarboxylic acid [23–25] are versatile building blocks to construct polymeric architectures due to their variety of bridging abilities [26–28]. In this work, our selection of isophthalic acid (ip ligand) as the main building block is based on the following considerations: (a) It has multiple coordination sites that may generate structures of higher dimensions. (b) It has two carboxylate groups which may be completely or partially deprotonated and thus result in acidity-dependent coordination modes. (c) It can act as both a hydrogen-bond acceptor or a hydrogen-bond donor because of the presence of the deprotonated carboxylate groups. (d) It can form short bridges via one carboxylate end or long bridges via the benzene ring [29]. On the other hand, we were interested in the reactions associated by auxiliary ligands, which can play an important role in the syntheses of coordination polymers with interesting structural topologies. The bidentate N-containing ligands, such as 4,4 0 -bipy [30] and 1,10-phenanthroline [31], are frequently chosen as auxiliary ligands in many recently reported synthetic systems. Here, we combined isophthalic acid and 4,4 0 -bipy ligands as a mixed ligand system to react with Cu(NO3)2 Æ 3H2O through carefully controlling hydrothermal conditions. The three newly obtained copper complexes [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n (1), [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O (2), and [Cu(ipH)2(4,4 0 -bipy)]n (3) exhibit various topological structures.
2. Experimental 2.1. Synthesis 2.1.1. Materials All chemicals and reagents are commercially available and were used as received without further purification. Infrared spectra (KBr pellets) were recorded in the range from 4000 to 400 cm1 on a Nicolet Magna 750 FT-IR spectrometer. X-ray photoelectron spectroscopy (XPS) measurements were done with a PHI Quantum 2000. XPS System with a monochromatic Al Ka source (1486.6 eV) and a charge neutralizer. The electron paramagnetic resonance spectra (EPR) were carried out on a ER-420 spectrometer of Bruker Company (X-band, 100 kHz modulation magnetic field,
rectangular TE102-type cavity) at room temperature. The thermogravimetric analyses (TGA) were performed in flowing N2 on a Universal V2.4F TA instrument. The C, H and N microanalyses were recorded with an Elemental Vario EL III elemental analyzer. 2.1.2. Synthesis of [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n The mixture of Cu(NO3)2 Æ 3H2O (0.241 g, 1 mmol), 4,4 0 -bipyridine(0.078 g, 0.5 mmol), and isophthalic acid (0.083 g, 0.5 mmol) in water(18 ml) was placed in a 25 ml teflon-lined stainless steel reactor and heated to 433 K for 76 h, and then cooled to room temperature over 3 days. Green prism single crystals suitable for Xray diffraction were obtained (yield 72%, based on Cu). Anal. calc. for C31H20Cu2N3O8 (689.58): C, 53.99; H, 2.92; N, 6.09. Found: C, 53.60; H, 2.77; N, 6.12%. IR (cm1, KBr): 3435m, 3152m, 1635s, 1608s, 1576m, 1535m, 1487m, 1435m, 1400s, 1218m, 1156m, 1073m, 945w, 810m, 749m, 740m, 704m, 656w, 639w, 525w, 486w. 2.1.3. Synthesis of [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O The mixture of Cu(NO3)2 Æ 3H2O (0.121 g, 0.5 mmol), 4,4 0 -bipyridine(0.078 g, 0.5 mmol), and isophthalic acid (0.083 g, 0.5 mmol) in water(18 ml) was placed in a 25 ml teflon-lined stainless steel reactor and heated to 443 K for 76 h, and then cooled to room temperature over 3 days. Green needle single crystals suitable for X-ray diffraction were obtained (yield 70%, based on Cu). Anal. calc. for C18H18CuN2O7 (437.88): C, 49.37; H, 4.14; N, 6.40. Found: C, 49.01; H, 3.98; N, 6.53%. IR (cm1, KBr): 3435m, 3112m, 1610s, 1566m, 1491m, 1478m, 1434m,1396s, 1371s, 1270m, 1220m, 1156m, 1098m, 1072m, 818s, 740m, 719s, 643m, 543w. 2.1.4. Synthesis of [Cu(ipH)2(4,4 0 -bipy)]n The mixture of Cu(NO3)2 Æ 3H2O (0.121 g, 0.5 mmol), 4,4 0 -bipyridine (0.078 g, 0.5 mmol), and isophthalic acid (0.166 g, 1 mmol) in water (18 ml) was placed in a 25 ml teflon-lined stainless steel reactor and heated to 433 K for 76 h, and then cooled to room temperature over 3 days. Blue prism single crystals suitable for X-ray diffraction were obtained (yield 80%, based on Cu). Anal. calc. for C26H18CuN2O8 (549.96): C, 56.83; H, 3.30; N, 5.10. Found: C, 56.36; H, 2.98; N, 5.28%. IR (cm1, KBr): 3095s, 1922w, 1849w, 1711s, 1608s, 1555m, 1542m, 1486m, 1438m, 1412s, 1277m, 1220s, 1160m, 1078m, 1051w, 1018m, 927m, 907m, 879m, 825s, 794m, 727s, 696s, 689s, 647m, 565m, 553m, 526w, 468m, 431m. 2.2. Crystal structure determination The crystal data of the complexes 1–3 and the parameters of data collection are summarized in Table 1, selected bond lengths and angles in Table 2. Intensity
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
3349
Table 1 Crystallographic data for the complexes 1–3
Empirical formula Formula weight Crystal system Space group Crystal color ˚) a (A ˚) b (A ˚) c (A a () b () c () ˚ 3) V (A Z Dcalc (g cm3) l (mm1) F(0 0 0) Temperature (K) ˚) k(Mo Ka) (A Reflections collections Unique reflections Observed reflections [I > 2r(I)] Rint Parameters S on F2 R1 [I > 2r(I)] wR2 [I > 2r(I)] R1 (all data) wR2 (all data)
1
2
3
C31H21Cu2N3O8 690.59 triclinic P 1 green 10.68830(10) 10.9078(2) 14.7842(2) 91.8380(10) 93.3030(10) 118.6390(10) 1506.73(4) 2 1.522 1.467 700 293(2) 0.71073 7867 5276 4372 0.0230 401 1.067 0.0556 0.1306 0.0729 0.1480
C18H18CuN2O7 437.88 monoclinic C2/c green 23.3806(8) 11.1291(5) 16.7895(5) 90.00 122.808(2) 90.00 3671.86(17) 8 1.584 1.234 1800 293(2) 0.71073 5470 3177 2544 0.0305 256 1.097 0.0595 0.1284 0.0802 0.1438
C26H18CuN2O8 549.96 orthorhombic Fdd2 blue 39.7575(9) 10.3307(4) 11.1347(4) 90.00 90.00 90.00 4573.3(3) 8 1.598 1.013 2248 293(2) 0.71073 3307 1589 1525 0.0269 175 1.046 0.0303 0.0732 0.0330 0.0757
data for the complexes 1–3 were measured with a Siemens Smart CCD diffractometer with graphite-mono˚ ) at 298 K. chromated Mo Ka radiation (k = 0.71073 A Empirical absorption corrections were applied by use of the SADABS program. The structures were solved by direct methods and all calculations were performed with the aid of the SHELXL PC program. The structures were refined by full-matrix, least-squares minimization of P (Fo Fc)2 with anisotropic thermal parameters for all atoms except H atoms.
3. Results and discussion 3.1. Syntheses Formation reactions of the three complexes are given as follows: 1:1:2 160˚C
ipH2 + 4,4'-bipy + Cu(NO3)2 3H2O
1:1:1 170˚C 2:1:1 160˚C
The preparations of these three complexes depend on the choices of proper synthetic conditions. With the same starting materials, they were obtained by carefully controlling the metal-to-ligand ratios and the formation of temperature. When the temperature was raised to 180 C (molar ratio = 1:1:1), we also obtained a complex [Cu2(ipO)(4,4 0 -bipy)] (ipOH = 2-hydroxyisophthalate), which has been reported by Chen et al. [32]. Complex 1 is a mixed-valence copper(I,II) complex, implying that CuII has undergone reduction process during the synthesis. Some similar complexes are presented, which implies that CuII can be reduced to CuI by 4,4 0 -bipy or pyridine derivatives under hydrothermal conditions [33,34]. Isophthalic acid (ipH2) was chosen as the main ligand due to its rich coordination modes. As shown in Scheme 1, three different coordination modes of the carboxylate groups are found in complexes 1–3. The secondary building units (SBUs) constructed by Cu atoms and ip
[CuIICuI(ip)(ipH)(4,4'-bipy)3/2]n (1)
[Cu(ip)(4,4'-bipy)]n
3nH2O (2)
[Cu(ipH)2 (4,4'-bipy)]n (3)
3350
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
Table 2 ˚ ) and angles () for the three complexes Selected bond lengths (A Complex 1 Cu(1)–O(2) Cu(1)–O(6) Cu(1)–O(1)#1 Cu(1)–O(5)#1 Cu(1)–N(1)#2 Cu(1)–Cu(1)#1 Cu(2)–N(2) Cu(2)–N(3) Cu(2)–O(8) O(2)–Cu(1)–O(6) O(2)–Cu(1)–O(1)#1 O(6)–Cu(1)–O(1)#1 O(2)–Cu(1)–O(5)#1 O(6)–Cu(1)–O(5)#1 O(1)#1–Cu(1)–O(5)#1 O(2)–Cu(1)–N(1)#2 O(6)–Cu(1)–N(1)#2 O(1)#1–Cu(1)–N(1)#2 O(5)#1–Cu(1)–N(1)#2 O(2)–Cu(1)–Cu(1)#1 O(6)–Cu(1)–Cu(1)#1 O(1)#1–Cu(1)–Cu(1)#1 O(5)#1–Cu(1)–Cu(1)#1 N(1)#2–Cu(1)–Cu(1)#1 N(2)–Cu(2)–N(3) N(2)–Cu(2)–O(8) N(3)–Cu(2)–O(8)
Complex 2 Cu(1)–O(1) Cu(1)–N(2)#1 Cu(1)–N(1) Cu(1)–O(3)#2 Cu(1)–O(2)#3 O(1)–Cu(1)–N(2)#1 O(1)–Cu(1)–N(1) N(2)#1–Cu(1)–N(1) O(1)–Cu(1)–O(3)#2 N(2)#1–Cu(1)–O(3)#2 N(1)–Cu(1)–O(3)#2 O(1)–Cu(1)–O(2)#3 N(2)#1–Cu(1)–O(2)#3 N(1)–Cu(1)–O(2)#3 O(3)#2–Cu(1)–O(2)#3
Complex 3 Cu(1)–O(4) Cu(1)–O(4)#1 Cu(1)–N(2) Cu(1)–N(1) O(4)–Cu(1)–O(4)#1 O(4)–Cu(1)–N(2) O(4)#1–Cu(1)–N(2) O(4)–Cu(1)–N(1) O(4)#1–Cu(1)–N(1) N(2)–Cu(1)–N(1)
1.958(3) 1.958(4) 1.968(4) 1.970(4) 2.152(4) 2.6468(10) 1.924(4) 1.930(4) 2.159(4)] 89.93(17) 167.84(15) 88.20(17) 88.69(17) 167.72(15) 90.59(18) 95.34(15) 98.77(17) 96.82(16) 93.51(17) 82.82(10) 84.58(10) 85.05(11) 83.14(11) 176.20(13) 147.85(19) 106.09(17) 104.13(18)
1.974(3) 2.020(4) 2.026(4) 2.043(3) 2.225(4) 87.73(16) 93.86(16) 176.86(18) 144.70(15) 92.12(16) 88.15(16) 124.33(14) 89.27(16) 87.60(16) 90.96(14)
1.966(2) 1.966(2) 2.027(5) 2.037(5) 174.19(16) 92.91(8) 92.91(8) 87.09(8) 87.09(8) 180.0
Symmetry codes: 1, #1 x, y + 1, z; #2 x + 1, y + 1, z + 1; 2, #1 x,y + 1,z; #2 x 1/2,y + 1/2, z 1/2; #3 x + 3/2, y + 1/ 2, z + 1; 3, #1 x, y, z.
ligands are further connected by the auxiliary ligand 4,4 0 -bipy to generate different topological structures.
3.2. Crystal structures 3.2.1. [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n (1) Complex 1 exhibits a mixed-valence 2-D interpenetrating grid framework. As shown in Fig. 1, the crystal structure of 1 contains two types of Cu centers. Firstly, Cu1 is cupric with a distorted square pyramid geometry, which is five-coordinated by four O atoms of the carboxylate groups from four different ip (or ipH) ligands (Cu– ˚ ) and one O distances in the range of 1.958(3)–1.970(4) A 0 N atom from 4,4 -bipy ligand (Cu–N distance 2.152(4) ˚ ). Four O atoms determine the square plane, and A ˚ out of the plane, while the N Cu1 atom lies 0.209 A atom occupies the apical position. A binuclear copperdicarboxylate paddle-wheel unit is constructed by four ip (or ipH) ligands and two Cu1 atoms with the ˚ , which is in Cu1 Cu1i separation of 2.6469(10) A agreement with the value of the reported binuclear copper-dicarboxylate paddle-wheel unit, {[Cu2(ip)2(pyri˚ ) [33]. This is a new type of the dine)2]4}n (2.668 A paddle-wheel structure because there co-exist two coordinated and two free carboxylate groups in complex 1. Secondly, Cu2 is cuprous. It is three-coordinated by two N atoms of two 4,4 0 -bipy ligands (Cu–N distances ˚ , respectively) and one O atom of 1.925(4) and 1.930(4) A ˚ ] in a triangular of carboxylate group [Cu–O 2.159(4) A geometry. The ip ligand in 1 exhibits two kinds of coordination modes (ip and ipH forms) to connect Cu centers. As illustrated in Scheme 1 and Fig. 1, each of the two opposite ip ligands acts as a l3-bridge to link three Cu atoms (two Cu1 atoms and one Cu2 atom, Scheme 1a), while each of the two opposite ipH ligands chelates two Cu atoms (Scheme 1b) by one carboxylate group, the other carboxylate group is left free. As shown in Fig. 2(a), each 4,4 0 -bipy ligand alternately links two Cu atoms (one Cu1 and one Cu2, or two Cu2 atoms, Cu–N distances in the range ˚ ), giving rise to a 1-D chain. Two 1.925(4)–2.152(4) A Cu atoms (Cu1 and Cu2) from adjacent two chains are connected by ip ligand, leading to a 2-D grid-like layer structure with two different grids (dimension: ˚ · 11.132 A ˚ and 9.306 A ˚ · 21.116 A ˚ , respec8.006 A tively) as shown in Fig. 2(b). An attractive structural feature of 1 is that it possesses a twofold interpenetrating open framework structure (Scheme 2). Each 4,4 0 -bipy ligand between two Cu2 atoms traverses the smaller grid of the other layer. Although several structures containing ipH2 and 4,4 0 -bipy ligands have been reported [35,36], this is the first example of interpenetrating composite network amongst the complexes of the M/ipH2/4,4 0 -bipy system.
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354 O
O
Cu
O
O
Cu
O
C
O
O
Cu
C O
Cu
C O
Cu
C
C
3351
C OH
O
OH
Cu
(b)
(a)
(c)
Scheme 1. The coordination modes found for the isophthalate groups.
O7 O5 N3 Cu2
i Cu1
O1 O8
N2
O6 O2 Cu1 ii N1
O4 O3
N1
Fig. 1. The paddle-wheel structure of 1 with two kinds of ip coordination modes; H atoms have been omitted for clarity. Symmetry code: (i) x, 1 y, z; (ii) 1 x, 1 y, 1 z.
˚ . Each CuII atom is five-coordiseparation by 4.145 A nated by three O atoms and two N atoms in a trigonal-bipyramidal geometry. Three O atoms of three different bridging carboxylate groups define a trigonal ˚ ] and two N equatorial plane [average Cu–O 2.081(3) A 0 atoms of two trans-related l-4,4 -bipy ligands [Cu–N ˚ , respectively] occudistances are 2.020(4) and 2.026(4) A ˚ out py the apical positions. The Cu atom lies 0.013(3) A of the plane. Each ip ligand in 2 acts as l3-bridge to link three Cu atoms through its three carboxylate O atoms (Scheme 1a) and each copper(II) center was coordinated by three ip ligands. Eight-membered rings and 16-membered rings are alternately arranged along a axis, giving rise to a 1-D double-chain structure (Fig. 3(b)). The further linkages of these chains via l-4,4 0 -bipy ligands in the axial positions generate an infinite 2-D neutral box-like architecture with dimensions of ca. 4.145 · 10.045 · ˚ 3 and with the N–Cu–N angle being almost 11.129 A 180(176.86(18)) (Fig. 4). The molecular packing of 2 is shown in Fig. 5. The adjacent grids are staggered in such a way that they
3.2.2. [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O (2) Complex 2 consists of 2-D box-like [Cu(ip)(4,4 0 -bipy)]n bilayers and free water molecules. As shown in Fig. 3(a), two equivalent Cu(II) atoms are bridged by syn–anti carboxylate ends of ip ligands with Cu Cu
Fig. 2. (a) The 1-D chain structure in 1. (b) The 2-D grid-like layer structure in 1, showing two different grids.
Scheme 2. A schematic view of twofold interpenetrating open framework structure in 1. Herein, the nodes present Cu atoms.
3352
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
CU1 O1
O4 O2
O3
N1
11.129
N2
(a)
O4
O1
4.145
10.045
Cu1 O2
O3
Fig. 4. Perspective view of the 2-D box-like framework in 2.
(b) Fig. 3. (a) Perspective view of the coordination environment of center Cu atom in 2. (b) The 1-D double-chain in 2.
are slipped in one direction in an ABAB fashion. In 2, the ip rings lying in both sides of the grid adopt an orientation that can be regarded as being trans to one another, and favor the face-to-face p–p stacking interactions between the iparomat ip groups from adjacent layers, the shortest intermolecular face-to-face aro˚ , close to the values of matic ring separation is ca. 3.53 A the p–p stacking interactions in pure aromatic compounds. 3.2.3. [Cu(ipH)2(4,4 0 -bipy)]n (3) Complex 3 features a 1-D linear chain structure. As shown in Fig. 6, the Cu(II) center with the square plane coordination environment is surrounded by two N atoms from two 4,4 0 -bipy ligands and two O atoms from two carboxylate groups. The Cu atoms situate in the square plane. The dihedral angle between two pyridyl rings is about 80.44. It is interesting that the angles of N1–Cu–N2 and N2–N1–Cu are all 180, implying that the 4,4 0 -bipy ligands and Cu atoms link each other to form a 1-D linear chain which infinitely propagates along ac plane. Each ipH ligand links only one Cu atom by one carboxylate groups, while the other carboxylate group of ipH ligand is left free. The ipH ligands are symmetrically arranged in two sides of the chains with Cu–O ˚ and the O–Cu–O bond anbond length being 1.966(2) A gle being 174.19(16).
Fig. 5. Perspective view of the inter-layer p–p stacking mode in 2.
3.3. The characteristic of oxidation state of Cu centers for 1 Complex 1 is a mixed-valence copper(I,II) coordination complex. The oxidation state of Cu atoms can be confirmed by its XPS spectrum. The XPS spectrum of 1 shows the evident shoulder peaks of 2P3/2 and 2P1/2 at 932.6 and 952.4 eV, respectively, suggesting the presence of CuI in the compound (Fig. 7). Furthermore, the powder EPR peak at atmospheric temperature shows the existence of CuII. The structure of complex 1 contains the binuclear [Cu2O8] paddle-wheel units. As a consequence of an electron exchange interaction, the EPR spectrum of a binuclear CuII complex can look very different from that of an analogous mononuclear one. Owing to the CuII–CuII interaction bridged by carboxylate groups, the EPR spectrum of 1
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
N1 Cu1 O5
N2
O4
O11 O12
Fig. 6. Local environments around Cu(II) center in 3; H atoms have been omitted for clarity.
demonstrates two sets of signals for effective S states S = 1 and S = 1/2, respectively. The experimental spectrum was well reproduced using the parameters in an axial symmetry of S = 1, gi = 2.4126, g^ = 2.1180, D = 0.376 cm1; S = 1/2, gi = 2.2866, g^ = 2.0903; and E = 0 cm1. Additionally, the CuI atom is commonly three- or four-coordinated, while the CuII atom is commonly fiveor six-coordinated. As discussed in Section 3.2, the three-coordinated geometry of Cu2 and five-coordinated geometry of Cu1 also support their respective valences. The green prism crystal color of 1 also means that complex 1 may contain CuII moiety because the CuII complex is usually in green or blue color, while the CuI complex is usually in red or pale yellow color. 3.4. Thermal analyses The thermogravimetric analyses (TGA) of complexes 1–3 were conducted under N2 atmosphere when they
3353
were heated to 500 C with a 15 C/min temperature ramp. Their thermal decomposition behaviors are very similar to each other. No obvious decompositions are observed below 290 C. Complex 1 undergoes a rapid and significant weight loss of 59.87% in the temperature ranges of 304– 337 C, which may be the concomitant release of the 4,4 0 -bipy and l2-bridged ip ligands, with a calculated value of 57.83%. For complex 2, it will decompose in two steps owing to the existence of free water molecules. However, the TGA curve of complex 2 presents only one step with the weight loss of 54.22% in the temperature ranges of 291–313 C, implying that the free water molecules and the other components may be lost synchronously. Complex 3 begins to decompose at 295 C with the weight loss of 70.09%. These results predicate that some unknown decomposition procedures may happen at the higher temperature. The similar thermal behaviors of complexes 1–3 are closely associated with the nature of metal atoms and the coordinating ligands. In these three complexes, all the Cu centers are all coordinated by ip (or ipH) and 4,4 0 -bipy ligands despite their different coordination geometries.
4. Conclusion In summary, three new copper-organic complexes with unique topological structures have been synthesized by hydrothermal reaction from the same starting materials under different conditions (the molar ratio and temperature). These results show that hydrothermal reactions are not only practicable to obtain the stable coordination polymers but also sensitive to certain experimental controls. In addition, our results also offer the possibility to get completely different topological structures by varying hydrothermal reactional conditions even when the same starting materials are used.
5. Supplementary material CCDC data with reference numbers 240377, 244427 and 244428 contain the supplementary crystallographic details for the three complexes. Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223 336 033; e-mail: [email protected], www: http://www.ccdc.cam.ac.uk).
Acknowledgments
Fig. 7. High resolution XPS spectrum of Cu element of 1.
This work is supported by the National Natural Science Foundation of China under project No. 20173063,
3354
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
the State Key Basic Research and Development Plan of China (001CB108906), and the NSF of Fujian Province (E0020001). We thank Ms. Xin Huang for her useful discussion about EPR spectrum.
References [1] M.-L. Tong, S. Kitagawa, H.-C. Chang, M. Ohba, Chem. Commun. (2004) 418. [2] P.M. Forster, A.R. Burbank, C. Livage, G. Fe´rey, A.K. Cheetham, Chem. Commun. (2004) 368. [3] A.J. Blake, N.R. Brooks, N.R. Champness, P.A. Cooke, A.M. Deveson, D. Fenske, P. Hubberstey, W.-S. Li, M. Schro¨der, Dalton Trans. (1999) 2103. [4] P.-Q. Zheng, Y.-P. Ren, L.-S. Long, R.-B. Huang, L.-S. Zheng, Inorg. Chem. 44 (2005) 1190. [5] M.A. Withersby, A.J. Blake, N.R. Champness, P.A. Cooke, P. Hubberstey, W.-S. Li, M. Schro¨der, Inorg. Chem. 38 (1999) 2259. [6] J.R. Black, N.R. Champness, W. Levason, G. Reid, Chem. Commun. (1995) 1277. [7] J.R. Black, N.R. Champness, W. Levason, G. Reid, Dalton Trans. (1995) 3439. [8] A. Gavezzotti, Acc. Chem. Res. 27 (1994) 309. [9] M.J. Zaworotko, Angew Chem., Int. Ed. 39 (2000) 3052. [10] A.K. Powell, S.L. Heath, D. Gatteschi, L. Pardi, R. Sessoli, G. Spina, F. Del Giallo, F. Pieralli, J. Am. Chem. Soc. 117 (1995) 2491. [11] C.S. Cundy, P.A. Cox, Chem. Rev. 103 (2003) 663. [12] R. Murugavel, M.G. Walawalkar, M. Dan, H.W. Roesky, C.N.R. Rao, Acc. Chem. Res. 37 (2004) 763. [13] A. Ranganathan, V.R. Pedireddi, C.N.R. Rao, J. Am. Chem. Soc. 121 (1999) 1752. [14] S. Feng, R. Xu, Acc. Chem. Res. 34 (2001) 239. [15] C.-D. Wu, C.-Z. Lu, S.-F. Lu, H.-H. Zhuang, J.-S. Huang, Inorg. Chem. Commun. 5 (2002) 171.
[16] Y. Kang, Y.-G. Yao, Y.-Y. Qin, J. Zhang, Y.-B. Chen, Z.-J. Li, Y.-H. Wen, J.-K. Cheng, R.-F. Hu, Chem. Commun. (2004) 1046. [17] Y.-H. Wen, J. Zhang, J.-K. Cheng, Z.-J. Li, Y.-Y. Qin, Y. Kang, R.-F. Hu, Y.-G. Yao, Acta Crystallogr., Sect. C 60 (2004) m248. [18] J.-K. Cheng, Y.-G. Yao, J. Zhang, Z.-J. Li, Z.-W. Cai, X.-Y. Zhang, Z.-N. Chen, Y.-B. Chen, Y. Kang, Y.-Y. Qin, Y.-H. Wen, J. Am. Chem. Soc. 126 (2004) 7796. [19] Y.-H. Wen, J.-K. Cheng, J. Zhang, Z.-J. Li, Y. Kang, Y.-G. Yao, Inorg. Chem. Commun. 7 (2004) 1120. [20] J. Zhang, Z.-J. Li, Y. Kang, J.-K. Cheng, Y.-G. Yao, Inorg. Chem. 43 (2004) 8085. [21] R. Cao, Q. Shi, D. Sun, M. Hong, W. Bi, Y. Zhao, Inorg. Chem. 41 (2002) 6161. [22] T.-B. Lu, H. Xiang, R.L. Luck, L. Jiang, Z.-W. Mao, L.-N. Ji, New J. Chem. 26 (2002) 969. [23] A. Thirumurugan, S. Natarajan, Eur. J. Inorg. Chem. (2004) 762. [24] J.-C. Yao, W. Huang, B. Li, S. Gou, Y. Xu, Inorg. Chem. Commun. 5 (2002) 711. [25] X.-M. Zhang, M.-L. Tong, M.-L. Gong, X.-M. Chen, Eur. J. Inorg. Chem. (2003) 138. [26] O.M. Yaghi, G. Li, H. Li, Nature 378 (1995) 703. [27] H.J. Choi, M.P. Suh, J. Am. Chem. Soc. 120 (1998) 10622. [28] F.A. Cotton, L.M. Daniels, C. Lin, C.A. Murillo, Chem. Commun. (1999) 841. [29] L.-P. Zhang, Y.-H. Wan, L.-P. Jin, Polyhedron 22 (2003) 981. [30] X.-M. Zhang, X.-M. Chen, Eur. J. Inorg. Chem. (2003) 413. [31] G. Fernandez, M. Corbella, J. Mahia, M.A. Maestro, Eur. J. Inorg. Chem. (2002) 2502. [32] J. Tao, Y. Zhang, M.-L. Tong, X.-M. Chen, Tan Yuen, C.L. Lin, X.-Y. Huang, J. Li, Chem. Commun. (2002) 1342. [33] S.A. Bourne, J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem. Int. Ed. 40 (2001) 2111. [34] O.M. Yaghi, H. Li, J. Am. Chem. Soc. 117 (1995) 10401. [35] J. Tao, M.-L. Tong, J.-X. Shi, X.-M. Chen, S.W. Ng, Chem. Commun. (2000) 2043. [36] J. Tao, X. Yin, R. Huang, L. Zheng, Inorg. Chem. Commun. 5 (2002) 1000.
Hydrothermal syntheses, crystal structures and characterizations of three new copper coordination polymers Yi-Hang Wen a
a,b,c
, Jian-Kai Cheng a, Yun-Long Feng b, Jian Zhang Zhao-Ji Li a, Yuan-Gen Yao a,*
a,c
,
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, PR China b Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, PR China c Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China Received 26 January 2005; received in revised form 22 April 2005; accepted 5 May 2005 Available online 15 June 2005
Abstract Three new copper complexes, [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n (1), [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O (2), and [Cu(ipH)2(4,4 0 -bipy)]n (3), have been hydrothermally synthesized by the reaction of Cu(NO3)2 Æ 3H2O with isophthalic acid (ipH2) and 4,4 0 -bipyridine (4,4 0 bipy) under different reaction conditions. Complex 1, a mixed-valence copper(I,II) complex, exhibits a 2-D interpenetrating grid framework, in which five-coordinated CuII and three-coordinated CuI environments are established. The oxidation states of center Cu atoms have been confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectra (EPR). Complex 2 features a 2-D box-like bilayer architecture, in which CuII atoms are linked by ip ligands to form a 1-D double-chain and the resulting chains are further strutted by the 4,4 0 -bipy ligands. In complex 3, two bridging 4,4 0 -bipy ligands and two terminal ipH ligands confine the CuII center in a square plane coordination geometry. The whole molecule of 3 was arranged into a 1-D linear chain structure. Additionally, the thermogravimetric analyses (TGA) for complexes 1–3 are also discussed in this paper. 2005 Elsevier B.V. All rights reserved. Keywords: Hydrothermal synthesis; Reaction condition; Coordination architecture; Mixed ligand; Copper complex
1. Introduction The design and synthesis of novel coordination architectures controlled by varying the reaction conditions (including temperature [1,2], metal-to-ligand ratio [3], pH value [4], solvents [5], and counteranions [6,7]) are of great interest in coordination chemistry. However, how to synthesize desirable architectures with useful properties is still a major challenge to chemists in this research field [8–10]. Recently, hydrothermal synthesis has *
Corresponding author. Tel.: +86 591 83711523; fax: +86 591 83714946. E-mail address: [email protected] (Y.-G. Yao). 0020-1693/$ - see front matter 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2005.05.004
gained impressive progress [11–13], of which the increasing interest derives from its advantages in terms of high reactivity of reactants, easy control of solution or interface reactions, formation of metastable and unique condensed phases, less air pollution, and low energy consumption [14]. Hydrothermal technique provides a powerful tool for the construction of such kind of materials containing unique structures and special properties. The mechanism of hydrothermal reactions is shifting from the kinetic control to the thermodynamic control, making the molecular structures obtained by this method more difficult to expect compared to those obtained by the conventional solution method [15]. Nevertheless, if the reaction conditions, of which temperature and
3348
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
metal-to-ligand ratio of reaction conditions are vital, are properly controlled, it is possible to construct new materials with desired useful properties. The main strategy widely used in this area is the building-block approach. Hence, our studies are mainly focused on selecting suitable multidentate organic ligands or mixed ligands under appropriate conditions to construct novel coordination architectures [16–20]. As known, benzoic multicarboxylate ligands such as 1,2,4,5-benzenetetracarboxylic acid [21], 1,3,5-benzenetricarboxylic acid [22], and 1,2 (1,3 or 1, 4)-benzenedicarboxylic acid [23–25] are versatile building blocks to construct polymeric architectures due to their variety of bridging abilities [26–28]. In this work, our selection of isophthalic acid (ip ligand) as the main building block is based on the following considerations: (a) It has multiple coordination sites that may generate structures of higher dimensions. (b) It has two carboxylate groups which may be completely or partially deprotonated and thus result in acidity-dependent coordination modes. (c) It can act as both a hydrogen-bond acceptor or a hydrogen-bond donor because of the presence of the deprotonated carboxylate groups. (d) It can form short bridges via one carboxylate end or long bridges via the benzene ring [29]. On the other hand, we were interested in the reactions associated by auxiliary ligands, which can play an important role in the syntheses of coordination polymers with interesting structural topologies. The bidentate N-containing ligands, such as 4,4 0 -bipy [30] and 1,10-phenanthroline [31], are frequently chosen as auxiliary ligands in many recently reported synthetic systems. Here, we combined isophthalic acid and 4,4 0 -bipy ligands as a mixed ligand system to react with Cu(NO3)2 Æ 3H2O through carefully controlling hydrothermal conditions. The three newly obtained copper complexes [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n (1), [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O (2), and [Cu(ipH)2(4,4 0 -bipy)]n (3) exhibit various topological structures.
2. Experimental 2.1. Synthesis 2.1.1. Materials All chemicals and reagents are commercially available and were used as received without further purification. Infrared spectra (KBr pellets) were recorded in the range from 4000 to 400 cm1 on a Nicolet Magna 750 FT-IR spectrometer. X-ray photoelectron spectroscopy (XPS) measurements were done with a PHI Quantum 2000. XPS System with a monochromatic Al Ka source (1486.6 eV) and a charge neutralizer. The electron paramagnetic resonance spectra (EPR) were carried out on a ER-420 spectrometer of Bruker Company (X-band, 100 kHz modulation magnetic field,
rectangular TE102-type cavity) at room temperature. The thermogravimetric analyses (TGA) were performed in flowing N2 on a Universal V2.4F TA instrument. The C, H and N microanalyses were recorded with an Elemental Vario EL III elemental analyzer. 2.1.2. Synthesis of [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n The mixture of Cu(NO3)2 Æ 3H2O (0.241 g, 1 mmol), 4,4 0 -bipyridine(0.078 g, 0.5 mmol), and isophthalic acid (0.083 g, 0.5 mmol) in water(18 ml) was placed in a 25 ml teflon-lined stainless steel reactor and heated to 433 K for 76 h, and then cooled to room temperature over 3 days. Green prism single crystals suitable for Xray diffraction were obtained (yield 72%, based on Cu). Anal. calc. for C31H20Cu2N3O8 (689.58): C, 53.99; H, 2.92; N, 6.09. Found: C, 53.60; H, 2.77; N, 6.12%. IR (cm1, KBr): 3435m, 3152m, 1635s, 1608s, 1576m, 1535m, 1487m, 1435m, 1400s, 1218m, 1156m, 1073m, 945w, 810m, 749m, 740m, 704m, 656w, 639w, 525w, 486w. 2.1.3. Synthesis of [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O The mixture of Cu(NO3)2 Æ 3H2O (0.121 g, 0.5 mmol), 4,4 0 -bipyridine(0.078 g, 0.5 mmol), and isophthalic acid (0.083 g, 0.5 mmol) in water(18 ml) was placed in a 25 ml teflon-lined stainless steel reactor and heated to 443 K for 76 h, and then cooled to room temperature over 3 days. Green needle single crystals suitable for X-ray diffraction were obtained (yield 70%, based on Cu). Anal. calc. for C18H18CuN2O7 (437.88): C, 49.37; H, 4.14; N, 6.40. Found: C, 49.01; H, 3.98; N, 6.53%. IR (cm1, KBr): 3435m, 3112m, 1610s, 1566m, 1491m, 1478m, 1434m,1396s, 1371s, 1270m, 1220m, 1156m, 1098m, 1072m, 818s, 740m, 719s, 643m, 543w. 2.1.4. Synthesis of [Cu(ipH)2(4,4 0 -bipy)]n The mixture of Cu(NO3)2 Æ 3H2O (0.121 g, 0.5 mmol), 4,4 0 -bipyridine (0.078 g, 0.5 mmol), and isophthalic acid (0.166 g, 1 mmol) in water (18 ml) was placed in a 25 ml teflon-lined stainless steel reactor and heated to 433 K for 76 h, and then cooled to room temperature over 3 days. Blue prism single crystals suitable for X-ray diffraction were obtained (yield 80%, based on Cu). Anal. calc. for C26H18CuN2O8 (549.96): C, 56.83; H, 3.30; N, 5.10. Found: C, 56.36; H, 2.98; N, 5.28%. IR (cm1, KBr): 3095s, 1922w, 1849w, 1711s, 1608s, 1555m, 1542m, 1486m, 1438m, 1412s, 1277m, 1220s, 1160m, 1078m, 1051w, 1018m, 927m, 907m, 879m, 825s, 794m, 727s, 696s, 689s, 647m, 565m, 553m, 526w, 468m, 431m. 2.2. Crystal structure determination The crystal data of the complexes 1–3 and the parameters of data collection are summarized in Table 1, selected bond lengths and angles in Table 2. Intensity
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
3349
Table 1 Crystallographic data for the complexes 1–3
Empirical formula Formula weight Crystal system Space group Crystal color ˚) a (A ˚) b (A ˚) c (A a () b () c () ˚ 3) V (A Z Dcalc (g cm3) l (mm1) F(0 0 0) Temperature (K) ˚) k(Mo Ka) (A Reflections collections Unique reflections Observed reflections [I > 2r(I)] Rint Parameters S on F2 R1 [I > 2r(I)] wR2 [I > 2r(I)] R1 (all data) wR2 (all data)
1
2
3
C31H21Cu2N3O8 690.59 triclinic P 1 green 10.68830(10) 10.9078(2) 14.7842(2) 91.8380(10) 93.3030(10) 118.6390(10) 1506.73(4) 2 1.522 1.467 700 293(2) 0.71073 7867 5276 4372 0.0230 401 1.067 0.0556 0.1306 0.0729 0.1480
C18H18CuN2O7 437.88 monoclinic C2/c green 23.3806(8) 11.1291(5) 16.7895(5) 90.00 122.808(2) 90.00 3671.86(17) 8 1.584 1.234 1800 293(2) 0.71073 5470 3177 2544 0.0305 256 1.097 0.0595 0.1284 0.0802 0.1438
C26H18CuN2O8 549.96 orthorhombic Fdd2 blue 39.7575(9) 10.3307(4) 11.1347(4) 90.00 90.00 90.00 4573.3(3) 8 1.598 1.013 2248 293(2) 0.71073 3307 1589 1525 0.0269 175 1.046 0.0303 0.0732 0.0330 0.0757
data for the complexes 1–3 were measured with a Siemens Smart CCD diffractometer with graphite-mono˚ ) at 298 K. chromated Mo Ka radiation (k = 0.71073 A Empirical absorption corrections were applied by use of the SADABS program. The structures were solved by direct methods and all calculations were performed with the aid of the SHELXL PC program. The structures were refined by full-matrix, least-squares minimization of P (Fo Fc)2 with anisotropic thermal parameters for all atoms except H atoms.
3. Results and discussion 3.1. Syntheses Formation reactions of the three complexes are given as follows: 1:1:2 160˚C
ipH2 + 4,4'-bipy + Cu(NO3)2 3H2O
1:1:1 170˚C 2:1:1 160˚C
The preparations of these three complexes depend on the choices of proper synthetic conditions. With the same starting materials, they were obtained by carefully controlling the metal-to-ligand ratios and the formation of temperature. When the temperature was raised to 180 C (molar ratio = 1:1:1), we also obtained a complex [Cu2(ipO)(4,4 0 -bipy)] (ipOH = 2-hydroxyisophthalate), which has been reported by Chen et al. [32]. Complex 1 is a mixed-valence copper(I,II) complex, implying that CuII has undergone reduction process during the synthesis. Some similar complexes are presented, which implies that CuII can be reduced to CuI by 4,4 0 -bipy or pyridine derivatives under hydrothermal conditions [33,34]. Isophthalic acid (ipH2) was chosen as the main ligand due to its rich coordination modes. As shown in Scheme 1, three different coordination modes of the carboxylate groups are found in complexes 1–3. The secondary building units (SBUs) constructed by Cu atoms and ip
[CuIICuI(ip)(ipH)(4,4'-bipy)3/2]n (1)
[Cu(ip)(4,4'-bipy)]n
3nH2O (2)
[Cu(ipH)2 (4,4'-bipy)]n (3)
3350
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
Table 2 ˚ ) and angles () for the three complexes Selected bond lengths (A Complex 1 Cu(1)–O(2) Cu(1)–O(6) Cu(1)–O(1)#1 Cu(1)–O(5)#1 Cu(1)–N(1)#2 Cu(1)–Cu(1)#1 Cu(2)–N(2) Cu(2)–N(3) Cu(2)–O(8) O(2)–Cu(1)–O(6) O(2)–Cu(1)–O(1)#1 O(6)–Cu(1)–O(1)#1 O(2)–Cu(1)–O(5)#1 O(6)–Cu(1)–O(5)#1 O(1)#1–Cu(1)–O(5)#1 O(2)–Cu(1)–N(1)#2 O(6)–Cu(1)–N(1)#2 O(1)#1–Cu(1)–N(1)#2 O(5)#1–Cu(1)–N(1)#2 O(2)–Cu(1)–Cu(1)#1 O(6)–Cu(1)–Cu(1)#1 O(1)#1–Cu(1)–Cu(1)#1 O(5)#1–Cu(1)–Cu(1)#1 N(1)#2–Cu(1)–Cu(1)#1 N(2)–Cu(2)–N(3) N(2)–Cu(2)–O(8) N(3)–Cu(2)–O(8)
Complex 2 Cu(1)–O(1) Cu(1)–N(2)#1 Cu(1)–N(1) Cu(1)–O(3)#2 Cu(1)–O(2)#3 O(1)–Cu(1)–N(2)#1 O(1)–Cu(1)–N(1) N(2)#1–Cu(1)–N(1) O(1)–Cu(1)–O(3)#2 N(2)#1–Cu(1)–O(3)#2 N(1)–Cu(1)–O(3)#2 O(1)–Cu(1)–O(2)#3 N(2)#1–Cu(1)–O(2)#3 N(1)–Cu(1)–O(2)#3 O(3)#2–Cu(1)–O(2)#3
Complex 3 Cu(1)–O(4) Cu(1)–O(4)#1 Cu(1)–N(2) Cu(1)–N(1) O(4)–Cu(1)–O(4)#1 O(4)–Cu(1)–N(2) O(4)#1–Cu(1)–N(2) O(4)–Cu(1)–N(1) O(4)#1–Cu(1)–N(1) N(2)–Cu(1)–N(1)
1.958(3) 1.958(4) 1.968(4) 1.970(4) 2.152(4) 2.6468(10) 1.924(4) 1.930(4) 2.159(4)] 89.93(17) 167.84(15) 88.20(17) 88.69(17) 167.72(15) 90.59(18) 95.34(15) 98.77(17) 96.82(16) 93.51(17) 82.82(10) 84.58(10) 85.05(11) 83.14(11) 176.20(13) 147.85(19) 106.09(17) 104.13(18)
1.974(3) 2.020(4) 2.026(4) 2.043(3) 2.225(4) 87.73(16) 93.86(16) 176.86(18) 144.70(15) 92.12(16) 88.15(16) 124.33(14) 89.27(16) 87.60(16) 90.96(14)
1.966(2) 1.966(2) 2.027(5) 2.037(5) 174.19(16) 92.91(8) 92.91(8) 87.09(8) 87.09(8) 180.0
Symmetry codes: 1, #1 x, y + 1, z; #2 x + 1, y + 1, z + 1; 2, #1 x,y + 1,z; #2 x 1/2,y + 1/2, z 1/2; #3 x + 3/2, y + 1/ 2, z + 1; 3, #1 x, y, z.
ligands are further connected by the auxiliary ligand 4,4 0 -bipy to generate different topological structures.
3.2. Crystal structures 3.2.1. [CuIICuI(ip)(ipH)(4,4 0 -bipy)3/2]n (1) Complex 1 exhibits a mixed-valence 2-D interpenetrating grid framework. As shown in Fig. 1, the crystal structure of 1 contains two types of Cu centers. Firstly, Cu1 is cupric with a distorted square pyramid geometry, which is five-coordinated by four O atoms of the carboxylate groups from four different ip (or ipH) ligands (Cu– ˚ ) and one O distances in the range of 1.958(3)–1.970(4) A 0 N atom from 4,4 -bipy ligand (Cu–N distance 2.152(4) ˚ ). Four O atoms determine the square plane, and A ˚ out of the plane, while the N Cu1 atom lies 0.209 A atom occupies the apical position. A binuclear copperdicarboxylate paddle-wheel unit is constructed by four ip (or ipH) ligands and two Cu1 atoms with the ˚ , which is in Cu1 Cu1i separation of 2.6469(10) A agreement with the value of the reported binuclear copper-dicarboxylate paddle-wheel unit, {[Cu2(ip)2(pyri˚ ) [33]. This is a new type of the dine)2]4}n (2.668 A paddle-wheel structure because there co-exist two coordinated and two free carboxylate groups in complex 1. Secondly, Cu2 is cuprous. It is three-coordinated by two N atoms of two 4,4 0 -bipy ligands (Cu–N distances ˚ , respectively) and one O atom of 1.925(4) and 1.930(4) A ˚ ] in a triangular of carboxylate group [Cu–O 2.159(4) A geometry. The ip ligand in 1 exhibits two kinds of coordination modes (ip and ipH forms) to connect Cu centers. As illustrated in Scheme 1 and Fig. 1, each of the two opposite ip ligands acts as a l3-bridge to link three Cu atoms (two Cu1 atoms and one Cu2 atom, Scheme 1a), while each of the two opposite ipH ligands chelates two Cu atoms (Scheme 1b) by one carboxylate group, the other carboxylate group is left free. As shown in Fig. 2(a), each 4,4 0 -bipy ligand alternately links two Cu atoms (one Cu1 and one Cu2, or two Cu2 atoms, Cu–N distances in the range ˚ ), giving rise to a 1-D chain. Two 1.925(4)–2.152(4) A Cu atoms (Cu1 and Cu2) from adjacent two chains are connected by ip ligand, leading to a 2-D grid-like layer structure with two different grids (dimension: ˚ · 11.132 A ˚ and 9.306 A ˚ · 21.116 A ˚ , respec8.006 A tively) as shown in Fig. 2(b). An attractive structural feature of 1 is that it possesses a twofold interpenetrating open framework structure (Scheme 2). Each 4,4 0 -bipy ligand between two Cu2 atoms traverses the smaller grid of the other layer. Although several structures containing ipH2 and 4,4 0 -bipy ligands have been reported [35,36], this is the first example of interpenetrating composite network amongst the complexes of the M/ipH2/4,4 0 -bipy system.
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354 O
O
Cu
O
O
Cu
O
C
O
O
Cu
C O
Cu
C O
Cu
C
C
3351
C OH
O
OH
Cu
(b)
(a)
(c)
Scheme 1. The coordination modes found for the isophthalate groups.
O7 O5 N3 Cu2
i Cu1
O1 O8
N2
O6 O2 Cu1 ii N1
O4 O3
N1
Fig. 1. The paddle-wheel structure of 1 with two kinds of ip coordination modes; H atoms have been omitted for clarity. Symmetry code: (i) x, 1 y, z; (ii) 1 x, 1 y, 1 z.
˚ . Each CuII atom is five-coordiseparation by 4.145 A nated by three O atoms and two N atoms in a trigonal-bipyramidal geometry. Three O atoms of three different bridging carboxylate groups define a trigonal ˚ ] and two N equatorial plane [average Cu–O 2.081(3) A 0 atoms of two trans-related l-4,4 -bipy ligands [Cu–N ˚ , respectively] occudistances are 2.020(4) and 2.026(4) A ˚ out py the apical positions. The Cu atom lies 0.013(3) A of the plane. Each ip ligand in 2 acts as l3-bridge to link three Cu atoms through its three carboxylate O atoms (Scheme 1a) and each copper(II) center was coordinated by three ip ligands. Eight-membered rings and 16-membered rings are alternately arranged along a axis, giving rise to a 1-D double-chain structure (Fig. 3(b)). The further linkages of these chains via l-4,4 0 -bipy ligands in the axial positions generate an infinite 2-D neutral box-like architecture with dimensions of ca. 4.145 · 10.045 · ˚ 3 and with the N–Cu–N angle being almost 11.129 A 180(176.86(18)) (Fig. 4). The molecular packing of 2 is shown in Fig. 5. The adjacent grids are staggered in such a way that they
3.2.2. [Cu(ip)(4,4 0 -bipy)]n Æ 3nH2O (2) Complex 2 consists of 2-D box-like [Cu(ip)(4,4 0 -bipy)]n bilayers and free water molecules. As shown in Fig. 3(a), two equivalent Cu(II) atoms are bridged by syn–anti carboxylate ends of ip ligands with Cu Cu
Fig. 2. (a) The 1-D chain structure in 1. (b) The 2-D grid-like layer structure in 1, showing two different grids.
Scheme 2. A schematic view of twofold interpenetrating open framework structure in 1. Herein, the nodes present Cu atoms.
3352
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
CU1 O1
O4 O2
O3
N1
11.129
N2
(a)
O4
O1
4.145
10.045
Cu1 O2
O3
Fig. 4. Perspective view of the 2-D box-like framework in 2.
(b) Fig. 3. (a) Perspective view of the coordination environment of center Cu atom in 2. (b) The 1-D double-chain in 2.
are slipped in one direction in an ABAB fashion. In 2, the ip rings lying in both sides of the grid adopt an orientation that can be regarded as being trans to one another, and favor the face-to-face p–p stacking interactions between the iparomat ip groups from adjacent layers, the shortest intermolecular face-to-face aro˚ , close to the values of matic ring separation is ca. 3.53 A the p–p stacking interactions in pure aromatic compounds. 3.2.3. [Cu(ipH)2(4,4 0 -bipy)]n (3) Complex 3 features a 1-D linear chain structure. As shown in Fig. 6, the Cu(II) center with the square plane coordination environment is surrounded by two N atoms from two 4,4 0 -bipy ligands and two O atoms from two carboxylate groups. The Cu atoms situate in the square plane. The dihedral angle between two pyridyl rings is about 80.44. It is interesting that the angles of N1–Cu–N2 and N2–N1–Cu are all 180, implying that the 4,4 0 -bipy ligands and Cu atoms link each other to form a 1-D linear chain which infinitely propagates along ac plane. Each ipH ligand links only one Cu atom by one carboxylate groups, while the other carboxylate group of ipH ligand is left free. The ipH ligands are symmetrically arranged in two sides of the chains with Cu–O ˚ and the O–Cu–O bond anbond length being 1.966(2) A gle being 174.19(16).
Fig. 5. Perspective view of the inter-layer p–p stacking mode in 2.
3.3. The characteristic of oxidation state of Cu centers for 1 Complex 1 is a mixed-valence copper(I,II) coordination complex. The oxidation state of Cu atoms can be confirmed by its XPS spectrum. The XPS spectrum of 1 shows the evident shoulder peaks of 2P3/2 and 2P1/2 at 932.6 and 952.4 eV, respectively, suggesting the presence of CuI in the compound (Fig. 7). Furthermore, the powder EPR peak at atmospheric temperature shows the existence of CuII. The structure of complex 1 contains the binuclear [Cu2O8] paddle-wheel units. As a consequence of an electron exchange interaction, the EPR spectrum of a binuclear CuII complex can look very different from that of an analogous mononuclear one. Owing to the CuII–CuII interaction bridged by carboxylate groups, the EPR spectrum of 1
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
N1 Cu1 O5
N2
O4
O11 O12
Fig. 6. Local environments around Cu(II) center in 3; H atoms have been omitted for clarity.
demonstrates two sets of signals for effective S states S = 1 and S = 1/2, respectively. The experimental spectrum was well reproduced using the parameters in an axial symmetry of S = 1, gi = 2.4126, g^ = 2.1180, D = 0.376 cm1; S = 1/2, gi = 2.2866, g^ = 2.0903; and E = 0 cm1. Additionally, the CuI atom is commonly three- or four-coordinated, while the CuII atom is commonly fiveor six-coordinated. As discussed in Section 3.2, the three-coordinated geometry of Cu2 and five-coordinated geometry of Cu1 also support their respective valences. The green prism crystal color of 1 also means that complex 1 may contain CuII moiety because the CuII complex is usually in green or blue color, while the CuI complex is usually in red or pale yellow color. 3.4. Thermal analyses The thermogravimetric analyses (TGA) of complexes 1–3 were conducted under N2 atmosphere when they
3353
were heated to 500 C with a 15 C/min temperature ramp. Their thermal decomposition behaviors are very similar to each other. No obvious decompositions are observed below 290 C. Complex 1 undergoes a rapid and significant weight loss of 59.87% in the temperature ranges of 304– 337 C, which may be the concomitant release of the 4,4 0 -bipy and l2-bridged ip ligands, with a calculated value of 57.83%. For complex 2, it will decompose in two steps owing to the existence of free water molecules. However, the TGA curve of complex 2 presents only one step with the weight loss of 54.22% in the temperature ranges of 291–313 C, implying that the free water molecules and the other components may be lost synchronously. Complex 3 begins to decompose at 295 C with the weight loss of 70.09%. These results predicate that some unknown decomposition procedures may happen at the higher temperature. The similar thermal behaviors of complexes 1–3 are closely associated with the nature of metal atoms and the coordinating ligands. In these three complexes, all the Cu centers are all coordinated by ip (or ipH) and 4,4 0 -bipy ligands despite their different coordination geometries.
4. Conclusion In summary, three new copper-organic complexes with unique topological structures have been synthesized by hydrothermal reaction from the same starting materials under different conditions (the molar ratio and temperature). These results show that hydrothermal reactions are not only practicable to obtain the stable coordination polymers but also sensitive to certain experimental controls. In addition, our results also offer the possibility to get completely different topological structures by varying hydrothermal reactional conditions even when the same starting materials are used.
5. Supplementary material CCDC data with reference numbers 240377, 244427 and 244428 contain the supplementary crystallographic details for the three complexes. Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223 336 033; e-mail: [email protected], www: http://www.ccdc.cam.ac.uk).
Acknowledgments
Fig. 7. High resolution XPS spectrum of Cu element of 1.
This work is supported by the National Natural Science Foundation of China under project No. 20173063,
3354
Y.-H. Wen et al. / Inorganica Chimica Acta 358 (2005) 3347–3354
the State Key Basic Research and Development Plan of China (001CB108906), and the NSF of Fujian Province (E0020001). We thank Ms. Xin Huang for her useful discussion about EPR spectrum.
References [1] M.-L. Tong, S. Kitagawa, H.-C. Chang, M. Ohba, Chem. Commun. (2004) 418. [2] P.M. Forster, A.R. Burbank, C. Livage, G. Fe´rey, A.K. Cheetham, Chem. Commun. (2004) 368. [3] A.J. Blake, N.R. Brooks, N.R. Champness, P.A. Cooke, A.M. Deveson, D. Fenske, P. Hubberstey, W.-S. Li, M. Schro¨der, Dalton Trans. (1999) 2103. [4] P.-Q. Zheng, Y.-P. Ren, L.-S. Long, R.-B. Huang, L.-S. Zheng, Inorg. Chem. 44 (2005) 1190. [5] M.A. Withersby, A.J. Blake, N.R. Champness, P.A. Cooke, P. Hubberstey, W.-S. Li, M. Schro¨der, Inorg. Chem. 38 (1999) 2259. [6] J.R. Black, N.R. Champness, W. Levason, G. Reid, Chem. Commun. (1995) 1277. [7] J.R. Black, N.R. Champness, W. Levason, G. Reid, Dalton Trans. (1995) 3439. [8] A. Gavezzotti, Acc. Chem. Res. 27 (1994) 309. [9] M.J. Zaworotko, Angew Chem., Int. Ed. 39 (2000) 3052. [10] A.K. Powell, S.L. Heath, D. Gatteschi, L. Pardi, R. Sessoli, G. Spina, F. Del Giallo, F. Pieralli, J. Am. Chem. Soc. 117 (1995) 2491. [11] C.S. Cundy, P.A. Cox, Chem. Rev. 103 (2003) 663. [12] R. Murugavel, M.G. Walawalkar, M. Dan, H.W. Roesky, C.N.R. Rao, Acc. Chem. Res. 37 (2004) 763. [13] A. Ranganathan, V.R. Pedireddi, C.N.R. Rao, J. Am. Chem. Soc. 121 (1999) 1752. [14] S. Feng, R. Xu, Acc. Chem. Res. 34 (2001) 239. [15] C.-D. Wu, C.-Z. Lu, S.-F. Lu, H.-H. Zhuang, J.-S. Huang, Inorg. Chem. Commun. 5 (2002) 171.
[16] Y. Kang, Y.-G. Yao, Y.-Y. Qin, J. Zhang, Y.-B. Chen, Z.-J. Li, Y.-H. Wen, J.-K. Cheng, R.-F. Hu, Chem. Commun. (2004) 1046. [17] Y.-H. Wen, J. Zhang, J.-K. Cheng, Z.-J. Li, Y.-Y. Qin, Y. Kang, R.-F. Hu, Y.-G. Yao, Acta Crystallogr., Sect. C 60 (2004) m248. [18] J.-K. Cheng, Y.-G. Yao, J. Zhang, Z.-J. Li, Z.-W. Cai, X.-Y. Zhang, Z.-N. Chen, Y.-B. Chen, Y. Kang, Y.-Y. Qin, Y.-H. Wen, J. Am. Chem. Soc. 126 (2004) 7796. [19] Y.-H. Wen, J.-K. Cheng, J. Zhang, Z.-J. Li, Y. Kang, Y.-G. Yao, Inorg. Chem. Commun. 7 (2004) 1120. [20] J. Zhang, Z.-J. Li, Y. Kang, J.-K. Cheng, Y.-G. Yao, Inorg. Chem. 43 (2004) 8085. [21] R. Cao, Q. Shi, D. Sun, M. Hong, W. Bi, Y. Zhao, Inorg. Chem. 41 (2002) 6161. [22] T.-B. Lu, H. Xiang, R.L. Luck, L. Jiang, Z.-W. Mao, L.-N. Ji, New J. Chem. 26 (2002) 969. [23] A. Thirumurugan, S. Natarajan, Eur. J. Inorg. Chem. (2004) 762. [24] J.-C. Yao, W. Huang, B. Li, S. Gou, Y. Xu, Inorg. Chem. Commun. 5 (2002) 711. [25] X.-M. Zhang, M.-L. Tong, M.-L. Gong, X.-M. Chen, Eur. J. Inorg. Chem. (2003) 138. [26] O.M. Yaghi, G. Li, H. Li, Nature 378 (1995) 703. [27] H.J. Choi, M.P. Suh, J. Am. Chem. Soc. 120 (1998) 10622. [28] F.A. Cotton, L.M. Daniels, C. Lin, C.A. Murillo, Chem. Commun. (1999) 841. [29] L.-P. Zhang, Y.-H. Wan, L.-P. Jin, Polyhedron 22 (2003) 981. [30] X.-M. Zhang, X.-M. Chen, Eur. J. Inorg. Chem. (2003) 413. [31] G. Fernandez, M. Corbella, J. Mahia, M.A. Maestro, Eur. J. Inorg. Chem. (2002) 2502. [32] J. Tao, Y. Zhang, M.-L. Tong, X.-M. Chen, Tan Yuen, C.L. Lin, X.-Y. Huang, J. Li, Chem. Commun. (2002) 1342. [33] S.A. Bourne, J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem. Int. Ed. 40 (2001) 2111. [34] O.M. Yaghi, H. Li, J. Am. Chem. Soc. 117 (1995) 10401. [35] J. Tao, M.-L. Tong, J.-X. Shi, X.-M. Chen, S.W. Ng, Chem. Commun. (2000) 2043. [36] J. Tao, X. Yin, R. Huang, L. Zheng, Inorg. Chem. Commun. 5 (2002) 1000.