КООРДИНАЦИОННАЯ ХИМИЯ, 2014, том 40, № 1, с. 49-54
УДК 541.49
STRUCTURAL DIVERSITY OF TWO NOVEL COMPLEXES OF Co(II) WITH ¿/s-TRIAZOLE LIGAND: FROM ONE-DIMENSIONAL CHAIN TO TWO-DIMENSIONAL POROUS NETWORK © 2014 Y. Y. Liu1, 2, *, P. Yang1, 2, and B. Ding1, 2, *
1Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal University, Tianjin, 300387P.R. China 2 Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry (Tianjin Normal University),
Ministry of Education, Tianjin, 300387P.R. China *E-mail: liuyuanyuan1973@yahoo.com.cn Received July 12, 2012
Using two novel bis-triazole ligands, 2,6-bis(1,2,4-triazole-4-yl)pyridine (L1) and 1,6-bis(1,2,4-triazole-1-yl)hexane (L2), one novel one-dimensional (1D) chain polymer [Co(NCS)2(L1)2]n (I) and one two-dimensional (2D) coordination polymer [Co(NCS)2(L2)2]n (II) have been synthesized and structurally characterized. The crystal crystallizes in the triclinic system for I, space group P1, a = 7.879(6), b = 8.830(7), c = 9.837(8) Â, a = 70.230(11)°, в = 115.474(6)°, у = 85.591(12)°, Z = 1. The crystal crystallizes in the mo-noclinic system for II, space group P1, a = 7.879(6), b = 8.830(7), c = 9.837(8) Â, a = 70.230(11)°, в = 115.474(6)°, у = 85.591(12)°, Z = 1. The structural diversity of these two new Co(II) complexes vary from 1D chain to 2D porous supramolecular network, which may be ascribed to ligand directing effects under similar synthetic conditions (L1 contains rigid pyridine spacers while L2 contains flexible hexane spacers).
DOI: 10.7868/S0132344X14010046
INTRODUCTION
Coordination polymers have aroused much interest as materials owing to potential new electronic, optical, magnetic, and catalytic properties, as well as intriguing structural motifs [1]. A key step for construction of polymeric transition metal complexes is to select appropriate multidentate bridging ligands [2]. Recently, new flexible bispolyazole-type ligands, such as 1- or 4-substituted 1,2,4-triazole rings tethered by an alkyl or rigid aromatic spacer, have been used to obtain a wide variety of polynuclear molecules and linear coordination polymers [3, 4]. 2,6-Bis(1,2,4-triazole-4-yl)pyri-dine (L1) and 1,6-bis(1,2,4-triazole-1-yl)hexane (L2) are excellent synthons for the construction of extended structures with the following distinctive characteristics.
N. N ^
N
x Л
N
(L1)
N^ /^N
I N-(CH2)6-N ^ N N
These two ligands can donate four nitrogen atoms in coordinating with metal ions to obtain unexpected structures.
On the other hand, neutral organic ligands containing rigid or flexible spacers, such as 4,4'-bipyridine, 1,2-bis(4'-pyridyl)ethane, 1,2-bis(4-pyridyl)propane and many others, have been used to generate a rich variety of metal-organic architectures with different metal ions by various reaction procedure. The ligands L1 and L2 represent another class of N-donor organic linkers for constructing coordination polymers. These ligands can produce architectures quite different from those obtained from pyridyl-based ligands [5]. For these ligands, a variety of zinc(II) and cadmium(II) compounds have been reported [6], while for the Co(II) compounds are less reported.
Recently we reported a series of Zn and Cd complexes with 2,6-bis(1,2,4-triazole-4-yl)ethane exhibiting the anion variations make different supra-molecular structure and the self-assembly of CdN4O2 poly-hedra from 2D to 1D [7]. As the continuation of this work, using two highly flexible bis-triazole ligands (L1 contains rigid pyridine spacers while L2 contains flexible hexane spacers), we isolated a novel 1D single-chain (I) and one two-dimensional (II) Co(II) com-
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Fig. 1. View of the 1D single chain structure of complex I.
pounds. The structural diversity of these two new Co(II) complexes vary from 1D chain to 2D porous supra-molecular network, which should be ascribed to ligand directing effects under similar synthetic conditions.
EXPERIMENTAL
The triazole ligands L1 and L2 were synthesized according to the literature method [8]. All other starting reagents were of A.R. grade and used as purchased. Analyses of C, H, and N were determined on a Perkin-Elmer 240 Elemental analyzer. The FT—IR spectrum was recorded as KBr discs on a Shimadzu IR-408 in-
frared spectrophotometer in range.
the 4000-600 cm-
Synthesis of [Co(NCS)2(L!)2]„ (I). A ethanol solution (10 mL) ofL1 (2.0 mmol) was added into an aqueous (10 mL) of CoCl2 • 6H2O (1.0 mmol) with stirring. The filtrate was refluxed for 1 h. The red crystals of I suitable for X-ray diffraction were obtained by evaporation of the filtrate. The yield was 55% (based on Co(II) salts).
For C20H14N16S2Co
anal. calcd., %: Found, %:
C, 39.94; C, 39.98;
H, 2.35; H, 2.41;
N, 37.26. N, 37.36.
Synthesis of [Co(NCS)2(L2)2]„ (II). A ethanol solution (10 mL) of L2 (2.0 mmol) was added into an aqueous (10 mL) of CoCl2 • 6H2O (1.0 mmol) with stirring. The filtrate was refluxed for 1 h. The red crystals of II suitable for X-ray diffraction were obtained by evapo-
ration of the filtrate. The yield was 47% (based on Co(II) salts).
For C22H32Ni4S2Co
anal. calcd., %: C, 42.92; H, 5.24; N, 31.85. Found, %: C, 42.96; H, 5.38; N, 31.96.
X-ray crystallography. The data were collected on a Bruker Smart-1000-CCD area detector, all using graph-ite-monchromated Mol^ radiation (X = 0.71073 A). The structures were solved by the direct method and subsequent Fourier difference techniques and refined using a full-matrix least-squares procedure on F2 with anisotropic thermal parameters for all non-hydrogen atoms (SHELXS-97 [9] and SHELXL-97 [10]). Hydrogen atoms were added geometrically and refined with riding model position parameters and fixed iso-tropic thermal parameters. Crystal data collection and refinement parameters are given in Table 1, the select 2. Supplementary material has been deposited with the Cambridge Crystallographic Data Centre (nos. 874718 (I) and 874715 (II); deposit@ccdc. cam.ac.uk or http://www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
The structure of I exhibits a double-stranded chain. The Co2+ ion is in a distorted octahedral arrangement, in which the equatorial plane is formed by four triazole nitrogen atoms and the axial positions are occupied by two trans-isothiocyanate ligands (Fig. 1). The Co—Nncs distances (2.069(3) A) are much shorter
than the Co-NL distances (2.201(3) and 2.161(3) A). The connections between Co2+ ions and NCS- groups are almost linear with a CNCo angle of 172.0(1)°. A dihedral angle of the two triazole rings of 26.6° and Co---Co separation across bridging L1 ligand is
KOOP^HH^HOHHAtf XHMH3 TOM 40 № 1 2014
Table 1. Crystallographic data and experimental details for complexes I and II
Parameter Value
I II
M 601.52 615.67
System Triclinic Monoclinic
Space group PI P2x/c
a, Â 7.879(6) 9.763(6)
b, Â 8.830(7) 18.112(12)
c, Â 9.837(8) 9.253(6)
a, deg 70.230(11) 90
ß, deg 85.591(12) 117.261(9)
Y, deg 65.399(10) 90
V, Â3 584.0(8) 1454.4(16)
Z 1 2
Pcalcd g/cm3 1.699 1.406
^(MoÄ"a), mm-1 0.794 0.773
F(000) 303 642
Crystal size, mm 0.16 x 0.12 x 0.10 0.20 x 0.14 x 0.10
Index ranges -7 < h < 9 -11 < h < 11
-9 < k < 10 -21 < k < 20
-9 < l < 11 -6 < l < 11
Reflections collected/unique 3210/2042 7754/2564
Rint 0.0248 0.0913
Reflections with I> 2o(I) 1512 1489
GOOF for F2 1.032 1.068
R index (I > 2a(I)) R1 = 0.0384 Rx = 0.1115
wR2 = 0.0829 wR2 = 0.2948
R index (all data) R1 = 0.0628 Rx = 0.1616,
wR2 = 0.0899 wR2 = 0.3269
Residual electron density (max/min), e Â-3 0.373/-0.273 1.904/-0.720
KOOP,3HHAUHOHHAH XHMH3 tom 40 № 1 2014
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Table 2. Selected bond distances (A) and angles (deg) for I and II
Bond d, A Bond d, A
Co(1)-N(8) 2.069(3) Co(1)-N(1) 2.161(3)
Co(1)-N(6) 2.201(3)
II
Co(1)-N(7) 2.118(8) Co(1)-N(1) 2.132(8)
Co(1)-N(6) 2.162(7)
Angle ю, deg Angle ю, deg
N(8)Co(1)N(1) 90.99(12) N(1)Co(1)N(6) 90.39(10)
N(8)Co(1)N(6) 92.49(10)
II
N(7)Co(1)N(1) 91.2(3) N(7)Co(1)N(6) 88.4(3)
N(1)Co(1)N(6) 88.7(7)
10.679(6) A. Two strands of L1 ligands are wrapped around each other and are held together by Co2+ ions, forming a double-stranded chain with 22-membered
rings. Because no solvent water molecules are involved into the coordination framework, only non-classical C—H---S and C—H—N interactions stabilize the framework and extend I into a 3D supra-molecular architecture (Fig. 2).
Figure 3 shows the asymmetric unit of II contains one Co2+ cation, four-half of L2 ligands and two thio-cyanate anions. The Co2+ ion, which resides at an inversion center, is octahedrally coordinated by two pairs of equivalent imine nitrogen atoms from L2 ligands in the equatorial plane (N(1), N(6), N(6^), N(U)) and two equivalent terminal thiocyanate ions occupying the axial positions (N(7) and N(7^)). Two triazole rings of the ligand rotate along the C—C single bond axis with the dihedral of 52.1°. The cis NCoN bond angles range from 88.4(3)° to 91.2(3)°, and the axial Co—N(7) distances (2.118(8) A) are similar to the equatorial Co—N(imine) distances (2.132(8) and 2.162(7) A), indicative of the nearly ideal octahedral environment. Each Co2+ ion is linked by four equivalent L2 ligands to its four neighboring Co2+ ions, thus affording 2D (4,4) grid layers parallel to the crystallo-graphic xy plane (Fig. 3).
The grid motif has the dimensions of 15.495(5) x x 15.495(5) A (metal-to-metal distances), and the Co-Co-Co corner angles (71.5(3)° and 108.4(7)°) within the motif are close to 90°, suggesting a rhombic geometry. The grid layers are closely stacked in an offset way (Fig. 4) with the cavity of each layer being occupied by the groups from the two neighboring layers, which are generated from the original one by unit translations along the x direction. Due to the interdig-itation between neighboring layers. The nearest inter-
Fig. 2. The three-dimensional supra-molecular pa
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