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The cation-templated self-assembly of 1,4-bis(2-methyl-1
H-imidazol-1-yl)butane (bmimb) with CuSCN gives rise to a novel two-dimensional network, namely
catena-poly[2,2′-dimethyl-1,1′-(butane-1,4-diyl)bis(1
H-imidazol-3-ium) [tetra-μ
2-thiocyanato-κ
4S:
S;κ
4S:
N-dicopper(I)]], {(C
12H
20N
4)[Cu
2(NCS)
4]}
n. The Cu
I cation is four-coordinated by one N and three S atoms, giving a tetrahedral geometry. One of the two crystallographically independent SCN
− anions acts as a μ
2-
S:
S bridge, binding a pair of Cu
I cations into a centrosymmetric [Cu
2(NCS)
2] subunit, which is further extended into a two-dimensional 4
4-sql net by another kind of SCN
− anion with an end-to-end μ
2-
S:
N coordination mode. Interestingly, each H
2bmimb dication, lying on an inversion centre, threads through one of the windows of the two-dimensional 4
4-sql net, giving a pseudorotaxane-like structure. The two-dimensional 4
4-sql networks are packed into the resultant three-dimensional supramolecular framework through bmimb–SCN N—H
N hydrogen bonds.
Supporting information
CCDC reference: 950431
A mixture of CuSCN (12.1 mg, 0.1 mmol), bmimp (4.4 mg, 0.02 mmol) and
N,N-dimethylformamide–acetonitrile (1:1 v:v, 1.5 ml) mixed solvent was sealed in a glass tube and heated to 413 K over a period
of 10 h, kept at 413 K for 50 h and then cooled slowly to 303 K over a period
of 13 h. Pale-yellow crystals of (I) were collected, washed with ethanol and
dried in air (yield 75%).
All H atoms were generated geometrically and allowed to ride on their parent
atoms in the riding-model approximation, with N—H = 0.86 Å, aromatic C—H
= 0.93Å, methyl C—H = 0.97 Å and methylene C—H = 0.96 Å, and with
Uiso(H) = 1.2Ueq(C).
Data collection: APEX2 (Bruker,2005); cell refinement: APEX2 (Bruker,2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).
catena-Poly[2,2'-dimethyl-1,1'-(butane-1,4-diyl)bis(1
H-imidazol-3-ium) [tetra-µ
2-thiocyanato-
κ4S:
S;
κ4S:
N-dicopper(I)]]
top
Crystal data top
(C12H20N4)[Cu2(NCS)4] | F(000) = 588 |
Mr = 579.72 | Dx = 1.685 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3077 reflections |
a = 9.6679 (8) Å | θ = 2.7–27.5° |
b = 9.7024 (8) Å | µ = 2.25 mm−1 |
c = 12.3648 (10) Å | T = 298 K |
β = 99.969 (1)° | Block, pale-yellow |
V = 1142.33 (16) Å3 | 0.24 × 0.13 × 0.10 mm |
Z = 4 | |
Data collection top
Bruker SMART APEXII CCD area-detector diffractometer | 2004 independent reflections |
Radiation source: fine-focus sealed tube | 1752 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.028 |
ϕ and ω scans | θmax = 25.0°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −11→11 |
Tmin = 0.615, Tmax = 0.806 | k = −6→11 |
5275 measured reflections | l = −12→14 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.038 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.123 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.084P)2 + 0.4244P] where P = (Fo2 + 2Fc2)/3 |
2004 reflections | (Δ/σ)max = 0.001 |
137 parameters | Δρmax = 0.74 e Å−3 |
0 restraints | Δρmin = −0.63 e Å−3 |
Crystal data top
(C12H20N4)[Cu2(NCS)4] | V = 1142.33 (16) Å3 |
Mr = 579.72 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.6679 (8) Å | µ = 2.25 mm−1 |
b = 9.7024 (8) Å | T = 298 K |
c = 12.3648 (10) Å | 0.24 × 0.13 × 0.10 mm |
β = 99.969 (1)° | |
Data collection top
Bruker SMART APEXII CCD area-detector diffractometer | 2004 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 1752 reflections with I > 2σ(I) |
Tmin = 0.615, Tmax = 0.806 | Rint = 0.028 |
5275 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.123 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.74 e Å−3 |
2004 reflections | Δρmin = −0.63 e Å−3 |
137 parameters | |
Special details top
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are
estimated using the full covariance matrix. The cell esds are taken into
account individually in the estimation of esds in distances, angles and torsion
angles; correlations between esds in cell parameters are only used when they
are defined by crystal symmetry. An approximate (isotropic) treatment of cell
esds is used for estimating esds involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and
goodness of fit S are based on F2, conventional R-factors R are based on F,
with F set to zero for negative F2. The threshold expression of F2 >
2sigma(F2) is used only for calculating R-factors(gt) etc. and is not
relevant to the choice of reflections for refinement. R-factors based on F2
are statistically about twice as large as those based on F, and R-factors based
on ALL data will be even larger. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cu1 | 1.03138 (5) | 0.47548 (5) | 0.39248 (3) | 0.0416 (2) | |
S1 | 0.83468 (8) | 0.60220 (8) | 0.43440 (6) | 0.0329 (2) | |
S2 | 1.19361 (9) | 0.61379 (10) | 0.32662 (7) | 0.0443 (3) | |
C1 | 0.7063 (4) | 0.4857 (4) | 0.4123 (3) | 0.0394 (8) | |
C2 | 1.1036 (3) | 0.7332 (4) | 0.2505 (2) | 0.0331 (7) | |
C3 | 0.3087 (4) | 0.1792 (5) | 0.3477 (3) | 0.0538 (10) | |
H3A | 0.2721 | 0.0947 | 0.3138 | 0.065* | |
H3B | 0.3810 | 0.2137 | 0.3106 | 0.065* | |
H3C | 0.2345 | 0.2459 | 0.3429 | 0.065* | |
C4 | 0.3680 (3) | 0.1536 (3) | 0.4644 (2) | 0.0324 (7) | |
C5 | 0.5005 (4) | 0.1670 (4) | 0.6280 (3) | 0.0414 (8) | |
H5 | 0.5709 | 0.1945 | 0.6850 | 0.050* | |
C6 | 0.4025 (3) | 0.0721 (4) | 0.6323 (2) | 0.0366 (7) | |
H6 | 0.3912 | 0.0210 | 0.6938 | 0.044* | |
C7 | 0.1967 (4) | −0.0274 (4) | 0.5013 (3) | 0.0421 (8) | |
H7A | 0.2093 | −0.1094 | 0.5468 | 0.051* | |
H7B | 0.1879 | −0.0560 | 0.4253 | 0.051* | |
C8 | 0.0634 (3) | 0.0459 (3) | 0.5178 (3) | 0.0354 (7) | |
H8A | 0.0529 | 0.1304 | 0.4752 | 0.042* | |
H8B | 0.0695 | 0.0700 | 0.5946 | 0.042* | |
N1 | 0.6152 (4) | 0.4078 (4) | 0.3963 (3) | 0.0623 (11) | |
N2 | 1.0444 (3) | 0.8189 (3) | 0.1978 (3) | 0.0479 (8) | |
N3 | 0.4766 (3) | 0.2169 (3) | 0.5216 (2) | 0.0366 (6) | |
H3 | 0.5255 | 0.2797 | 0.4967 | 0.044* | |
N4 | 0.3210 (3) | 0.0627 (3) | 0.5299 (2) | 0.0300 (6) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cu1 | 0.0425 (3) | 0.0401 (3) | 0.0418 (3) | −0.00673 (19) | 0.0058 (2) | −0.00521 (17) |
S1 | 0.0323 (5) | 0.0315 (4) | 0.0339 (4) | −0.0004 (3) | 0.0028 (3) | 0.0014 (3) |
S2 | 0.0331 (5) | 0.0501 (5) | 0.0492 (5) | 0.0024 (4) | 0.0059 (4) | 0.0200 (4) |
C1 | 0.036 (2) | 0.054 (2) | 0.0261 (15) | −0.0010 (18) | 0.0005 (14) | 0.0070 (14) |
C2 | 0.0314 (16) | 0.0392 (18) | 0.0280 (14) | −0.0063 (15) | 0.0034 (12) | −0.0016 (14) |
C3 | 0.050 (2) | 0.077 (3) | 0.0339 (17) | 0.014 (2) | 0.0056 (16) | 0.0059 (18) |
C4 | 0.0291 (16) | 0.0363 (17) | 0.0336 (15) | 0.0034 (14) | 0.0100 (13) | −0.0006 (14) |
C5 | 0.0333 (17) | 0.053 (2) | 0.0365 (16) | −0.0022 (17) | 0.0037 (14) | −0.0101 (16) |
C6 | 0.0333 (17) | 0.047 (2) | 0.0300 (15) | −0.0014 (16) | 0.0065 (13) | 0.0016 (14) |
C7 | 0.0331 (18) | 0.039 (2) | 0.053 (2) | −0.0068 (15) | 0.0057 (15) | −0.0095 (16) |
C8 | 0.0307 (17) | 0.0331 (16) | 0.0420 (17) | −0.0040 (14) | 0.0053 (14) | −0.0027 (14) |
N1 | 0.048 (2) | 0.090 (3) | 0.0446 (17) | −0.034 (2) | −0.0041 (14) | 0.0094 (18) |
N2 | 0.0467 (18) | 0.0448 (18) | 0.0504 (17) | 0.0015 (15) | 0.0030 (14) | 0.0135 (15) |
N3 | 0.0291 (14) | 0.0387 (15) | 0.0446 (15) | −0.0042 (13) | 0.0130 (12) | −0.0014 (13) |
N4 | 0.0216 (12) | 0.0329 (13) | 0.0352 (13) | −0.0034 (11) | 0.0043 (10) | −0.0056 (11) |
Geometric parameters (Å, º) top
Cu1—N2i | 1.952 (3) | C4—N4 | 1.330 (4) |
Cu1—S2 | 2.3165 (9) | C5—C6 | 1.329 (5) |
Cu1—S1 | 2.3954 (9) | C5—N3 | 1.383 (4) |
Cu1—S1ii | 2.4222 (9) | C5—H5 | 0.9300 |
Cu1—Cu1ii | 2.8676 (8) | C6—N4 | 1.374 (4) |
S1—C1 | 1.666 (4) | C6—H6 | 0.9300 |
S1—Cu1ii | 2.4222 (9) | C7—N4 | 1.479 (4) |
S2—C2 | 1.643 (3) | C7—C8 | 1.516 (5) |
C1—N1 | 1.151 (5) | C7—H7A | 0.9700 |
C2—N2 | 1.146 (4) | C7—H7B | 0.9700 |
C3—C4 | 1.478 (4) | C8—C8iii | 1.517 (6) |
C3—H3A | 0.9600 | C8—H8A | 0.9700 |
C3—H3B | 0.9600 | C8—H8B | 0.9700 |
C3—H3C | 0.9600 | N3—H3 | 0.8600 |
C4—N3 | 1.313 (4) | | |
| | | |
N2i—Cu1—S2 | 117.38 (10) | C6—C5—N3 | 106.1 (3) |
N2i—Cu1—S1 | 106.85 (10) | C6—C5—H5 | 126.9 |
S2—Cu1—S1 | 112.95 (4) | N3—C5—H5 | 126.9 |
N2i—Cu1—S1ii | 110.71 (10) | C5—C6—N4 | 107.9 (3) |
S2—Cu1—S1ii | 101.54 (3) | C5—C6—H6 | 126.0 |
S1—Cu1—S1ii | 106.94 (3) | N4—C6—H6 | 126.0 |
N2i—Cu1—Cu1ii | 122.74 (10) | N4—C7—C8 | 111.4 (3) |
S2—Cu1—Cu1ii | 119.65 (3) | N4—C7—H7A | 109.3 |
S1—Cu1—Cu1ii | 53.90 (2) | C8—C7—H7A | 109.3 |
S1ii—Cu1—Cu1ii | 53.04 (2) | N4—C7—H7B | 109.3 |
C1—S1—Cu1 | 102.29 (13) | C8—C7—H7B | 109.3 |
C1—S1—Cu1ii | 101.70 (12) | H7A—C7—H7B | 108.0 |
Cu1—S1—Cu1ii | 73.06 (3) | C7—C8—C8iii | 110.4 (3) |
C2—S2—Cu1 | 106.60 (11) | C7—C8—H8A | 109.6 |
N1—C1—S1 | 178.3 (4) | C8iii—C8—H8A | 109.6 |
N2—C2—S2 | 177.9 (3) | C7—C8—H8B | 109.6 |
C4—C3—H3A | 109.5 | C8iii—C8—H8B | 109.6 |
C4—C3—H3B | 109.5 | H8A—C8—H8B | 108.1 |
H3A—C3—H3B | 109.5 | C2—N2—Cu1iv | 172.3 (3) |
C4—C3—H3C | 109.5 | C4—N3—C5 | 109.6 (3) |
H3A—C3—H3C | 109.5 | C4—N3—H3 | 125.2 |
H3B—C3—H3C | 109.5 | C5—N3—H3 | 125.2 |
N3—C4—N4 | 107.9 (3) | C4—N4—C6 | 108.4 (3) |
N3—C4—C3 | 125.9 (3) | C4—N4—C7 | 126.6 (3) |
N4—C4—C3 | 126.2 (3) | C6—N4—C7 | 124.9 (3) |
Symmetry codes: (i) −x+2, y−1/2, −z+1/2; (ii) −x+2, −y+1, −z+1; (iii) −x, −y, −z+1; (iv) −x+2, y+1/2, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3···N1 | 0.86 | 2.05 | 2.889 (4) | 164 |
Experimental details
Crystal data |
Chemical formula | (C12H20N4)[Cu2(NCS)4] |
Mr | 579.72 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 298 |
a, b, c (Å) | 9.6679 (8), 9.7024 (8), 12.3648 (10) |
β (°) | 99.969 (1) |
V (Å3) | 1142.33 (16) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.25 |
Crystal size (mm) | 0.24 × 0.13 × 0.10 |
|
Data collection |
Diffractometer | Bruker SMART APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.615, 0.806 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5275, 2004, 1752 |
Rint | 0.028 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.123, 1.06 |
No. of reflections | 2004 |
No. of parameters | 137 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.74, −0.63 |
Selected geometric parameters (Å, º) topCu1—N2i | 1.952 (3) | Cu1—S1ii | 2.4222 (9) |
Cu1—S2 | 2.3165 (9) | Cu1—Cu1ii | 2.8676 (8) |
Cu1—S1 | 2.3954 (9) | | |
| | | |
N2i—Cu1—S2 | 117.38 (10) | N2i—Cu1—S1ii | 110.71 (10) |
N2i—Cu1—S1 | 106.85 (10) | S2—Cu1—S1ii | 101.54 (3) |
S2—Cu1—S1 | 112.95 (4) | S1—Cu1—S1ii | 106.94 (3) |
Symmetry codes: (i) −x+2, y−1/2, −z+1/2; (ii) −x+2, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N3—H3···N1 | 0.86 | 2.05 | 2.889 (4) | 164.0 |
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Inorganic supramolecular networks and coordination polymers have attracted considerable interest because of their fascinating crystal structures and potential applications in fields such as gas adsorption or separation, catalysis, optical materials and so on (Zhou et al., 2012; Yoon et al., 2012; Cui et al., 2012; Li et al., 2009). Of the supramolecular compound types reported, subgroups based on copper(I)–halide/pseudohalide aggregates are particularly interesting, due to their versatile motifs and luminescent properties (Peng et al., 2010; Hao et al., 2010; Xu et al., 2006). In contrast with the well studied coordination architectures of copper(I) halides, copper(I) pseudohalides are relatively unexplored. As a pseudohalide anion (Moss et al., 1995), thiocyanate (SCN-) possesses various bonding modes, such as a terminal mode, an end-on µ2-bridging mode, an end-to-end µ2-bridging mode and a 1,1,3-µ3-bridging mode (Niu et al., 2008), which diversifies the structures and makes structure prediction difficult. The most common strategy for achieving copper(I)–halide/pseudohalide networks is the reaction between CuI (or Cu powder) and halide/pseudohalide salts of the appropriate cation (Babich et al., 1996; Helgesson & Jagner, 1991; Domasevitch et al., 1999; Rusanova et al., 2000). Heterocyclic cation-templated synthesis, on the other hand, provides a new way of constructing polymeric CuSCN networks with target motifs (Raston et al., 1979; Song et al., 2012). However, the use of a cationic biimidazole-based template in the construction of polymeric Cu–SCN networks has not been reported. Based on the considerations above, we chose CuSCN and 1,4-bis(2-methyl-1H-imidazol-1-yl)butane (bmimb) to carry out the reaction under solvothermal conditions, which eventually gave rise to catena-poly[2,2'-dimethyl-1,1'-(butane-1,4-diyl)bis(1H-imidazol-3-ium) [tetra-µ2-thiocyanato-κ4S:S;κ4S:N-dicopper(I)], (I), with an anionic {[Cu2(NCS)4]2-}n network and H2bmimb cations accommodated in the network cavities.
As shown in Fig. 1, the asymmetric unit of (I) contains one CuI cation and two crystallographically independent SCN- anions, and a 2,2'-dimethyl-1,1'-(butane-1,4-diyl)bis(1H-imidazol-3-ium) (H2bmimb) dication lying on an inversion centre. The coordination environment of the CuI cation can be described as a slightly distorted tetrahedron defined by one N and three S atoms from SCN- anions [Cu—S = 2.3165 (9)–2.4222 (9) Å and Cu—N = 1.952 (3) Å]. The Cu—S and Cu—N bond lengths fall within the range previously reported for CuSCN complexes (Lv et al., 2009; Deluzet et al., 2002; Rahal et al., 1997). The distortion of the tetrahedron can be indicated by the calculated value of the τ4 parameter (Yang et al., 2007) to describe the geometry of a four-coordinate metal system, which is 0.92 for Cu1 (for an ideal tetrahedron, τ4 = 1).
In (I), the SCN- anions show two kinds of binding modes, µ2-S:S and µ2-N:S. The µ2-S:S SCN- anions bind a pair of inversion-centre related CuI cations to form a [Cu2(NCS)2] subunit, in which the distance between the two CuI cations is 2.8676 (8) Å, close to the sum of the ionic radii (2.80 Å; Bondi, 1964), indicating a weak CuI···CuI interaction. As shown in Fig. 2, each [Cu2(NCS)2] subunit is connected to four others by four µ2-N:S SCN- anions, forming an infinite two-dimensional 44-sql network along the bc plane (Wells, 1997). The distance between the [Cu2(NCS)2] subunits is 7.859 (5) Å, which is comparable with the values observed in other reported {[Cu2(NCS)4]2-}n networks, for example in {(bpe)[Cu2(NCS)4]}n [9.55 Å; bpe = ?,?'-(ethane-1,2-diyl)dipyridinium [Please complete ligand name]; Niu et al., 2008] and {(biqpp)[Cu2(NCS)4]}n [7.28 Å; biqpp = ?,?'-(propane-1,3-diyl)diisoquinolinium [Please complete ligand name]; Song et al., 2012].
The H2bmimb cations, with an anti–anti–anti configuration, are trapped in the network cavities. They thus act only for charge neutralization and do not coordinate to any metal centres. The two-dimensional 44-sql networks are packed into the resultant three-dimensional supramolecular framework through bmimb–SCN N—H···N hydrogen bonds.
The most outstanding feature of (I) is the rare polypseudorotaxane structure, consisting of the two-dimensional inorganic {[Cu2(NCS)4]2-}n network penetrated by the H2bmimb template cations. Along the a direction, each rhombus ring of the two-dimensional network is penetrated by H2bmimb cations (Fig. 3), leaving no space for solvent molecules. Heterocyclic cation-templated synthesis has been employed previously to construct Cu–SCN networks, but such rotaxane-like interlocking is rare because a rotaxanate interaction needs an ideal distance between the [Cu2(NCS)2] units in each rhombus molecular ring, neither too long nor too short [More details and a reference?].
In summary, polyrotaxane architectures consisting of a two-dimensional inorganic network perforated with organic molecules have rarely been reported, and thus (I) can be regarded as an unprecedented example of a polypseudorotaxane derived from the H2bmimb cation.