The structure of the title compound, poly[[[μ
3-
N′-(3-cyanobenzylidene)nicotinohydrazide]silver(I)] hexafluoroarsenate], {[Ag(C
14H
10N
4O)](AsF
6)}
n, at 173 K exhibits a novel stair-like two-dimensional layer and a three-dimensional supramolecular framework through C—H
Ag hydrogen bonds. The Ag
I cation is coordinated by three N atoms and one O atom from
N′-(3-cyanobenzylidene)nicotinohydrazide (
L) ligands, resulting in a distorted tetrahedral coordination geometry. The organic ligand acts as a μ
3-bridging ligand through the pyridyl and carbonitrile N atoms and deviates from planarity in order to adapt to the coordination geometry. Two ligands bridge two Ag
I cations to construct a small 2+2 Ag
2L2 ring. Four ligands bridge one Ag
I cation from each of four of these small rings to form a large grid. An interesting stair-like two-dimensional (3,6)-net is formed through Ag
I metal centres acting as three-connection nodes and through
L molecules as tri-linkage spacers.
Supporting information
CCDC reference: 734606
A solution of AgAsF6 (0.1 mmol) in methanol (10 ml) was carefully layered on
a solution of (3-cyanobenzylidene)nicotinohydrazide (L) (0.1 mmol) in
chloroform (10 ml) in a straight glass tube. After about two weeks, single
crystals suitable for X-ray analysis appeared at the boundary between the two
layers (yield ca 40%). Analysis calculated for C14H10AgAsF6N4O:
C 30.74, H 1.84, N 10.24%; found: C 30.89, H 1.77, N 10.27%. IR (KBr, ν,
cm-1): 3339 (m), 3068 (w), 2267 (m), 1663 (s),
1598 (w), 1534 (m), 1476 (w), 1429 (w), 1362
(w), 1290 (m), 1164 (w), 1145 (w), 955 (w),
810 (w), 705 (vs), 583 (w), 530 (w).
H atoms were placed in calculated positions and refined using a riding model
[C—H = 0.95 Å, N—H = 0.88 Å and Uiso(H) =
1.2Ueq(C,N)]. The highest peak in the final difference Fourier map
was 1.02 Å from atom F1 and the deepest hole was 0.66 Å from atom Ag1, but
the map was otherwise featureless.
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (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: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
Poly[[[µ
3-
N'-(3-cyanobenzylidene)nicotinohydrazide]silver(I)]
hexafluoroarsenate]
top
Crystal data top
[Ag(C14H10N4O)](AsF6) | F(000) = 1056 |
Mr = 547.05 | Dx = 2.084 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 4687 reflections |
a = 12.7022 (10) Å | θ = 2.5–27.5° |
b = 10.6710 (8) Å | µ = 3.11 mm−1 |
c = 13.5477 (11) Å | T = 173 K |
β = 108.316 (1)° | Block, colourless |
V = 1743.3 (2) Å3 | 0.29 × 0.22 × 0.20 mm |
Z = 4 | |
Data collection top
Bruker APEXII CCD area-detector diffractometer | 3988 independent reflections |
Radiation source: fine-focus sealed tube | 3330 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
ϕ and ω scans | θmax = 27.5°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −16→16 |
Tmin = 0.466, Tmax = 0.575 | k = −13→12 |
11028 measured reflections | l = −17→15 |
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)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.083 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0441P)2 + 1.0766P] where P = (Fo2 + 2Fc2)/3 |
3988 reflections | (Δ/σ)max = 0.001 |
244 parameters | Δρmax = 0.48 e Å−3 |
0 restraints | Δρmin = −0.64 e Å−3 |
Crystal data top
[Ag(C14H10N4O)](AsF6) | V = 1743.3 (2) Å3 |
Mr = 547.05 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 12.7022 (10) Å | µ = 3.11 mm−1 |
b = 10.6710 (8) Å | T = 173 K |
c = 13.5477 (11) Å | 0.29 × 0.22 × 0.20 mm |
β = 108.316 (1)° | |
Data collection top
Bruker APEXII CCD area-detector diffractometer | 3988 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 3330 reflections with I > 2σ(I) |
Tmin = 0.466, Tmax = 0.575 | Rint = 0.021 |
11028 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.083 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.48 e Å−3 |
3988 reflections | Δρmin = −0.64 e Å−3 |
244 parameters | |
Special details top
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 >
σ(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 | |
Ag1 | 0.46567 (2) | 0.42080 (2) | 0.720067 (18) | 0.04525 (9) | |
N1 | 0.7892 (2) | 0.1581 (2) | 1.17785 (19) | 0.0395 (5) | |
N2 | 0.5757 (2) | 0.1867 (2) | 0.87079 (18) | 0.0422 (6) | |
H14 | 0.6006 | 0.1125 | 0.8959 | 0.051* | |
N3 | 0.5292 (2) | 0.2041 (2) | 0.76497 (18) | 0.0367 (5) | |
N4 | 0.4610 (2) | 0.4308 (3) | 0.3436 (2) | 0.0505 (7) | |
O1 | 0.5429 (2) | 0.3875 (2) | 0.90517 (17) | 0.0480 (5) | |
C1 | 0.7640 (3) | 0.2276 (3) | 1.2496 (2) | 0.0503 (8) | |
H1 | 0.8045 | 0.2146 | 1.3208 | 0.060* | |
C2 | 0.6818 (3) | 0.3172 (4) | 1.2241 (3) | 0.0627 (11) | |
H2 | 0.6665 | 0.3655 | 1.2770 | 0.075* | |
C3 | 0.6220 (3) | 0.3361 (4) | 1.1211 (3) | 0.0525 (8) | |
H3 | 0.5661 | 0.3987 | 1.1018 | 0.063* | |
C4 | 0.6446 (2) | 0.2623 (3) | 1.0467 (2) | 0.0361 (6) | |
C5 | 0.7289 (2) | 0.1747 (3) | 1.0786 (2) | 0.0358 (6) | |
H5 | 0.7447 | 0.1241 | 1.0273 | 0.043* | |
C6 | 0.5827 (2) | 0.2850 (3) | 0.9353 (2) | 0.0368 (6) | |
C7 | 0.5010 (3) | 0.1073 (3) | 0.7080 (2) | 0.0412 (7) | |
H7 | 0.5134 | 0.0261 | 0.7383 | 0.049* | |
C8 | 0.4497 (2) | 0.1209 (3) | 0.5957 (2) | 0.0352 (6) | |
C9 | 0.3725 (3) | 0.0322 (3) | 0.5413 (2) | 0.0403 (6) | |
H9 | 0.3593 | −0.0403 | 0.5764 | 0.048* | |
C10 | 0.3153 (3) | 0.0483 (3) | 0.4373 (2) | 0.0421 (7) | |
H10 | 0.2619 | −0.0120 | 0.4017 | 0.051* | |
C11 | 0.3354 (3) | 0.1520 (3) | 0.3844 (2) | 0.0410 (7) | |
H11 | 0.2951 | 0.1642 | 0.3130 | 0.049* | |
C12 | 0.4159 (2) | 0.2382 (3) | 0.4378 (2) | 0.0355 (6) | |
C13 | 0.4730 (2) | 0.2234 (3) | 0.5425 (2) | 0.0351 (6) | |
H13 | 0.5276 | 0.2827 | 0.5778 | 0.042* | |
C14 | 0.4402 (3) | 0.3460 (3) | 0.3840 (2) | 0.0418 (7) | |
As1 | 0.68466 (3) | 0.82580 (3) | 0.92847 (3) | 0.04731 (11) | |
F1 | 0.6108 (3) | 0.9114 (3) | 0.9890 (3) | 0.1103 (11) | |
F2 | 0.7995 (3) | 0.8381 (5) | 1.0311 (2) | 0.1263 (14) | |
F3 | 0.6474 (3) | 0.6924 (2) | 0.9767 (2) | 0.0920 (8) | |
F4 | 0.5701 (2) | 0.8156 (3) | 0.8211 (2) | 0.0855 (8) | |
F5 | 0.7177 (2) | 0.9631 (2) | 0.8776 (2) | 0.0816 (7) | |
F6 | 0.7572 (2) | 0.7454 (2) | 0.8622 (2) | 0.0771 (7) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ag1 | 0.05425 (16) | 0.03737 (14) | 0.04115 (14) | −0.00764 (10) | 0.01072 (11) | 0.00614 (9) |
N1 | 0.0386 (13) | 0.0451 (14) | 0.0305 (12) | 0.0035 (11) | 0.0045 (10) | −0.0025 (10) |
N2 | 0.0566 (15) | 0.0335 (12) | 0.0280 (11) | 0.0033 (11) | 0.0012 (11) | 0.0030 (9) |
N3 | 0.0420 (13) | 0.0357 (12) | 0.0278 (11) | 0.0031 (10) | 0.0044 (10) | 0.0031 (9) |
N4 | 0.0599 (17) | 0.0460 (16) | 0.0484 (16) | −0.0061 (13) | 0.0210 (14) | 0.0084 (12) |
O1 | 0.0601 (14) | 0.0417 (12) | 0.0365 (11) | 0.0114 (10) | 0.0069 (10) | −0.0002 (9) |
C1 | 0.0502 (18) | 0.070 (2) | 0.0281 (14) | 0.0079 (16) | 0.0086 (13) | −0.0029 (14) |
C2 | 0.060 (2) | 0.088 (3) | 0.0375 (17) | 0.028 (2) | 0.0128 (16) | −0.0135 (17) |
C3 | 0.0491 (18) | 0.065 (2) | 0.0397 (16) | 0.0193 (16) | 0.0092 (14) | −0.0049 (15) |
C4 | 0.0342 (14) | 0.0425 (15) | 0.0300 (14) | −0.0008 (11) | 0.0077 (11) | −0.0008 (11) |
C5 | 0.0392 (14) | 0.0366 (14) | 0.0292 (13) | 0.0001 (11) | 0.0075 (11) | −0.0026 (10) |
C6 | 0.0381 (14) | 0.0393 (15) | 0.0316 (14) | 0.0010 (12) | 0.0091 (11) | 0.0024 (11) |
C7 | 0.0532 (17) | 0.0324 (15) | 0.0337 (14) | 0.0049 (13) | 0.0075 (13) | 0.0044 (11) |
C8 | 0.0433 (15) | 0.0296 (13) | 0.0324 (14) | 0.0049 (11) | 0.0114 (12) | −0.0007 (11) |
C9 | 0.0533 (17) | 0.0297 (14) | 0.0399 (15) | −0.0023 (12) | 0.0177 (14) | −0.0012 (11) |
C10 | 0.0506 (17) | 0.0366 (15) | 0.0383 (15) | −0.0102 (13) | 0.0125 (13) | −0.0093 (12) |
C11 | 0.0470 (16) | 0.0468 (17) | 0.0282 (13) | −0.0035 (13) | 0.0103 (12) | −0.0023 (12) |
C12 | 0.0437 (15) | 0.0326 (14) | 0.0334 (14) | −0.0003 (11) | 0.0165 (12) | 0.0021 (11) |
C13 | 0.0372 (14) | 0.0331 (14) | 0.0339 (14) | −0.0031 (11) | 0.0097 (12) | −0.0041 (11) |
C14 | 0.0479 (17) | 0.0410 (16) | 0.0379 (15) | −0.0020 (13) | 0.0157 (13) | −0.0011 (13) |
As1 | 0.0536 (2) | 0.0445 (2) | 0.04202 (19) | 0.00445 (14) | 0.01238 (15) | −0.00200 (13) |
F1 | 0.127 (3) | 0.096 (2) | 0.144 (3) | −0.0092 (18) | 0.093 (2) | −0.0450 (19) |
F2 | 0.0750 (18) | 0.236 (4) | 0.0504 (15) | −0.020 (2) | −0.0051 (13) | −0.003 (2) |
F3 | 0.114 (2) | 0.0740 (17) | 0.093 (2) | 0.0031 (15) | 0.0399 (17) | 0.0327 (15) |
F4 | 0.0696 (15) | 0.102 (2) | 0.0684 (15) | −0.0089 (14) | −0.0025 (13) | 0.0133 (14) |
F5 | 0.0957 (18) | 0.0479 (12) | 0.113 (2) | −0.0072 (12) | 0.0505 (16) | −0.0014 (13) |
F6 | 0.1012 (18) | 0.0667 (14) | 0.0728 (15) | 0.0294 (13) | 0.0410 (14) | 0.0064 (11) |
Geometric parameters (Å, º) top
Ag1—N4i | 2.151 (3) | C4—C6 | 1.486 (4) |
Ag1—N1ii | 2.293 (2) | C5—H5 | 0.9500 |
Ag1—O1 | 2.415 (2) | C7—C8 | 1.462 (4) |
Ag1—N3 | 2.462 (2) | C7—H7 | 0.9500 |
N1—C5 | 1.334 (4) | C8—C13 | 1.391 (4) |
N1—C1 | 1.339 (4) | C8—C9 | 1.395 (4) |
N1—Ag1iii | 2.293 (2) | C9—C10 | 1.378 (4) |
N2—C6 | 1.350 (4) | C9—H9 | 0.9500 |
N2—N3 | 1.381 (3) | C10—C11 | 1.384 (4) |
N2—H14 | 0.8800 | C10—H10 | 0.9500 |
N3—C7 | 1.272 (4) | C11—C12 | 1.397 (4) |
N4—C14 | 1.131 (4) | C11—H11 | 0.9500 |
N4—Ag1i | 2.151 (3) | C12—C13 | 1.384 (4) |
O1—C6 | 1.220 (3) | C12—C14 | 1.446 (4) |
C1—C2 | 1.378 (5) | C13—H13 | 0.9500 |
C1—H1 | 0.9500 | As1—F2 | 1.674 (3) |
C2—C3 | 1.378 (5) | As1—F3 | 1.694 (3) |
C2—H2 | 0.9500 | As1—F1 | 1.694 (3) |
C3—C4 | 1.379 (4) | As1—F6 | 1.707 (2) |
C3—H3 | 0.9500 | As1—F4 | 1.708 (2) |
C4—C5 | 1.384 (4) | As1—F5 | 1.726 (2) |
| | | |
N4i—Ag1—N1ii | 133.08 (10) | N3—C7—H7 | 120.0 |
N4i—Ag1—O1 | 116.06 (10) | C8—C7—H7 | 120.0 |
N1ii—Ag1—O1 | 104.56 (9) | C13—C8—C9 | 119.2 (3) |
N4i—Ag1—N3 | 129.89 (10) | C13—C8—C7 | 121.3 (3) |
N1ii—Ag1—N3 | 86.31 (9) | C9—C8—C7 | 119.4 (3) |
O1—Ag1—N3 | 67.08 (7) | C10—C9—C8 | 120.8 (3) |
C5—N1—C1 | 117.8 (3) | C10—C9—H9 | 119.6 |
C5—N1—Ag1iii | 120.4 (2) | C8—C9—H9 | 119.6 |
C1—N1—Ag1iii | 117.4 (2) | C9—C10—C11 | 120.4 (3) |
C6—N2—N3 | 119.2 (2) | C9—C10—H10 | 119.8 |
C6—N2—H14 | 120.4 | C11—C10—H10 | 119.8 |
N3—N2—H14 | 120.4 | C10—C11—C12 | 118.8 (3) |
C7—N3—N2 | 117.9 (2) | C10—C11—H11 | 120.6 |
C7—N3—Ag1 | 127.25 (19) | C12—C11—H11 | 120.6 |
N2—N3—Ag1 | 112.50 (17) | C13—C12—C11 | 121.2 (3) |
C14—N4—Ag1i | 168.5 (3) | C13—C12—C14 | 118.8 (3) |
C6—O1—Ag1 | 118.00 (19) | C11—C12—C14 | 120.0 (3) |
N1—C1—C2 | 122.5 (3) | C12—C13—C8 | 119.5 (3) |
N1—C1—H1 | 118.7 | C12—C13—H13 | 120.2 |
C2—C1—H1 | 118.7 | C8—C13—H13 | 120.2 |
C3—C2—C1 | 119.2 (3) | N4—C14—C12 | 178.6 (4) |
C3—C2—H2 | 120.4 | F2—As1—F3 | 91.25 (19) |
C1—C2—H2 | 120.4 | F2—As1—F1 | 91.49 (19) |
C2—C3—C4 | 118.8 (3) | F3—As1—F1 | 90.14 (16) |
C2—C3—H3 | 120.6 | F2—As1—F6 | 90.17 (17) |
C4—C3—H3 | 120.6 | F3—As1—F6 | 92.47 (14) |
C3—C4—C5 | 118.4 (3) | F1—As1—F6 | 176.88 (15) |
C3—C4—C6 | 119.0 (3) | F2—As1—F4 | 177.93 (17) |
C5—C4—C6 | 122.5 (3) | F3—As1—F4 | 90.50 (14) |
N1—C5—C4 | 123.2 (3) | F1—As1—F4 | 89.62 (17) |
N1—C5—H5 | 118.4 | F6—As1—F4 | 88.64 (15) |
C4—C5—H5 | 118.4 | F2—As1—F5 | 90.40 (19) |
O1—C6—N2 | 123.0 (3) | F3—As1—F5 | 177.99 (14) |
O1—C6—C4 | 121.1 (3) | F1—As1—F5 | 88.68 (14) |
N2—C6—C4 | 115.9 (2) | F6—As1—F5 | 88.67 (12) |
N3—C7—C8 | 119.9 (3) | F4—As1—F5 | 87.87 (14) |
| | | |
C6—N2—N3—C7 | −164.8 (3) | Ag1—O1—C6—C4 | 172.0 (2) |
C6—N2—N3—Ag1 | −0.8 (3) | N3—N2—C6—O1 | 5.1 (5) |
N4i—Ag1—N3—C7 | −93.8 (3) | N3—N2—C6—C4 | −173.6 (3) |
N1ii—Ag1—N3—C7 | 53.1 (3) | C3—C4—C6—O1 | 25.3 (5) |
O1—Ag1—N3—C7 | 160.6 (3) | C5—C4—C6—O1 | −150.9 (3) |
N4i—Ag1—N3—N2 | 104.0 (2) | C3—C4—C6—N2 | −155.9 (3) |
N1ii—Ag1—N3—N2 | −109.0 (2) | C5—C4—C6—N2 | 27.9 (4) |
O1—Ag1—N3—N2 | −1.54 (18) | N2—N3—C7—C8 | 179.0 (3) |
N4i—Ag1—O1—C6 | −120.4 (2) | Ag1—N3—C7—C8 | 17.7 (4) |
N1ii—Ag1—O1—C6 | 83.7 (2) | N3—C7—C8—C13 | 29.0 (5) |
N3—Ag1—O1—C6 | 4.2 (2) | N3—C7—C8—C9 | −148.5 (3) |
C5—N1—C1—C2 | −2.2 (5) | C13—C8—C9—C10 | −3.4 (4) |
Ag1iii—N1—C1—C2 | 154.4 (3) | C7—C8—C9—C10 | 174.1 (3) |
N1—C1—C2—C3 | 0.5 (6) | C8—C9—C10—C11 | 1.4 (5) |
C1—C2—C3—C4 | 1.5 (6) | C9—C10—C11—C12 | 1.2 (5) |
C2—C3—C4—C5 | −1.8 (5) | C10—C11—C12—C13 | −1.8 (5) |
C2—C3—C4—C6 | −178.1 (3) | C10—C11—C12—C14 | 178.7 (3) |
C1—N1—C5—C4 | 1.9 (5) | C11—C12—C13—C8 | −0.2 (4) |
Ag1iii—N1—C5—C4 | −154.0 (2) | C14—C12—C13—C8 | 179.3 (3) |
C3—C4—C5—N1 | 0.1 (5) | C9—C8—C13—C12 | 2.8 (4) |
C6—C4—C5—N1 | 176.3 (3) | C7—C8—C13—C12 | −174.7 (3) |
Ag1—O1—C6—N2 | −6.7 (4) | | |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1/2, −y+1/2, z−1/2; (iii) x+1/2, −y+1/2, z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H14···F5iv | 0.88 | 2.25 | 2.975 (4) | 140 |
N2—H14···F1iv | 0.88 | 2.47 | 3.308 (4) | 159 |
Symmetry code: (iv) x, y−1, z. |
Experimental details
Crystal data |
Chemical formula | [Ag(C14H10N4O)](AsF6) |
Mr | 547.05 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 173 |
a, b, c (Å) | 12.7022 (10), 10.6710 (8), 13.5477 (11) |
β (°) | 108.316 (1) |
V (Å3) | 1743.3 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 3.11 |
Crystal size (mm) | 0.29 × 0.22 × 0.20 |
|
Data collection |
Diffractometer | Bruker APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.466, 0.575 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11028, 3988, 3330 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.083, 1.03 |
No. of reflections | 3988 |
No. of parameters | 244 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.48, −0.64 |
Selected geometric parameters (Å, º) topAg1—N4i | 2.151 (3) | Ag1—O1 | 2.415 (2) |
Ag1—N1ii | 2.293 (2) | Ag1—N3 | 2.462 (2) |
| | | |
N4i—Ag1—N1ii | 133.08 (10) | N4i—Ag1—N3 | 129.89 (10) |
N4i—Ag1—O1 | 116.06 (10) | N1ii—Ag1—N3 | 86.31 (9) |
N1ii—Ag1—O1 | 104.56 (9) | O1—Ag1—N3 | 67.08 (7) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1/2, −y+1/2, z−1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H14···F5iii | 0.88 | 2.25 | 2.975 (4) | 139.9 |
N2—H14···F1iii | 0.88 | 2.47 | 3.308 (4) | 158.9 |
Symmetry code: (iii) x, y−1, z. |
The design and construction of novel coordination polymers are very important parts of crystal engineering, not only for functional materials purposes but also for the favorable architectures and topologies of these polymers (Murray & Dinca et al., 2009; Eddaoudi et al., 2001). Metal centers as connecting nodes and organic bridging ligands as spacers should be cogitatively selected before studies. For metal centers, silver ions are widely used because silver coordinating polymers possess strong luminescent emissions and antibiotic characters. In addition, the coordination number and metal stereochemistry for silver(I) is quite variable (Catalano et al., 1999; Dong et al., 2004; Zheng et al., 2003; Schottel et al., 2005). Furthermore, there are many significant inter- and intra-molecular interactions between silver centers (Ag···Ag metal interactions), and between silver and other elements, such as organic aromatic π systems (Ag···π interactions; Jung et al., 2004), O atoms (Ag···O interactions; Wang & Mak, 2002), S atoms (Ag···S interactions; Wang et al., 2006), halogen (X) atoms [X = F, Cl, Br and I; Ag···X interactions; Blake et al., 2000), and rare H, C, CH2 and CH3 (C—H···Ag weak hydrogen bonds, Ag···H—C agostic interactions and Ag···C organometallic interactions; Clarke et al., 2004; McMorran & Steel, 2002; Liu et al., 2006; Zhao & Mak, 2007). For organic ligands, pyridyl–carbonitrile ligands with labile coordinating properties and different coordinating groups with different coordinating abilities towards Ag atoms were used in some of our studies (Niu et al., 2007, 2008). For the series of Schiff base ligands synthesized from cyanobenzaldehyde and pyridylhydrazone, we noticed that, if we changed the position of the N atom on the pyridyl ring, the molecular or supramolecular structures of the silver coordination compounds were different. Thus, it should be reasonable to assume that, if the position of the carbonitrile group on the benzene ring is changed, a new silver coordinating compound with an unexpected structure might be obtained.
We report here the structure of a novel silver coordination polymer of the new bridging ligand N'-(3-cyanobenzylidene)nicotinohydrazide (L), namely {[Ag(C14H10N4O)](AsF6)}n, (I). Its crystal structure determined by X-ray diffraction shows that (I) possesses a novel stair-like two-dimensional layer structure. More interestingly, weak C—H···Ag hydrogen bonds were found connecting these two-dimensional layers, forming a three-dimensional framework.
In (I), the silver ion is four-coordinated by one O atom and one N atom (O1 and N3) from the hydrazide chain and by the pyridyl and carbonitrile N atoms (N1ii and N4i; for symmetry codes, see Table 1) from two other bridging ligands, giving a distorted tetrahedral coordination geometry (Fig. 1). Ligand donor atoms O1 and N3 are coordinated to the silver ion in a bidentate coordinating mode to form a planar five-membered chelate ring (Ag1/O1/C6/N2/N3). The Ag—O bond distance is 2.415 (2) Å, and the Ag–N bond distances range from 2.151 (3) Å to 2.462 (2) Å (Table 1). The Ag—Ncarbonitrile bond distance is the shortest. The distortion of the tetrahedral coordination geometry is largely a result of the widely varying bond angles about the metal center [67.08 (7)–133.08 (10)°; Table 2]. The hydrazide ligand molecule is distorted from planarity in accommodating the metal coordination centres. The Ag1/O1/C6/N2/N3 ring is not coplanar with the benzene ring of the same ligand [the dihedral angle is 47.15 (2)°; Fig. 2]. The plane of the pyridyl ring is also twisted slightly from that of the above-mentioned chelate ring and makes a dihedral angle of 74.91 (2)° with the plane of the aromatic ring. Two L molecules bridge pairs of Ag coordination centers through the carbonitrile N atom and the primary bidentate chelate ligand interaction, to form a small centrosymmetric 2+2 Ag2L2 ring. The Ag···Ag separation in one ring is 6.5147 (6)Å. Four of these small rings are linked to each other by pyridyl atom N1, coordinating to Ag atoms in adjacent rings to produce a large nearly rectangular grid. Thus, two Ag atoms from different 2+2 rings are bridged by the entire length of L via the pyridyl and carbonitrile N atoms, and this bridging ligand is not planar. The Ag···Ag separation for atoms bridged in this way is 13.2985 (9)Å. The distance between two neighbouring Ag atoms bridged via the bidentate hydrazide O1 and N3 atoms and the monodentate pyridyl N1 atom is 8.5129 (5)Å. The spaces within this grid are not void but occupied by two parallel benzene rings, which are also parallel to two pyridyl rings of the large grid. Weak π–π interactions exist between two neighbouring parallel benzene rings, and between neighbouring parallel benzene and pyridyl rings, with centroid–centroid distances of about 3.9Å, and interplanar angles of 0° and about 14°, respectively. These weak interactions help the stability of the large grid constructed by the deformed L molecules. The AsF6- counter-anions are located on the outside of the grids and are associated with the hydrazide chains through N—H···F hydrogen bonds (Table 2).
It is noteworthy that a stair-like two-dimensional (3,6)-net is formed through Ag metal centers acting as three-connection nodes and L molecules as tri-linkage spacers using two bottom and one middle coordinating atoms. These nets are unlike most reported two-dimensional planar brick-wall (3,6)-nets but can be seen as deformed or even folded planar (3,6)-nets driven by the tetrahedral coordination environment of the metal centers, instead of the square-planar type, together with the deformation from planarity of the L ligand molecule. Two adjacent ladders bend in two different directions, one up and the other down, both by nearly 90° (Fig. 3). Deformed hydrazide chains and pyridyl rings coordinating to Ag atoms are located at the corners of the stairs, whereas carbonitrile chains link two edges, constructing the equatorial and right platforms of the stairs (Fig. 4).
Another striking feature of the structure of this compound is the occurence of the rare intermolecular C—H···Ag interactions between two neighbouring stair-like layers. The intermolecular distances indicate the presence of obvious close complementary C—H···M close interactions between the metal centers and the pyridyl ring H atoms [Ag···H = 2.8394 (3) Å, Ag···C = 3.576 (4) Å and C—H···Ag = 135.0 (2)°]. From the above-mentioned bond distances and angle, such C—H···Ag close interactions should be described as a weak intermolecular C—H···M hydrogen bonding, as previously described (Thakur & Desiraju, 2005). Furthermore, donors and acceptors involve two separate coordination centers, strengthening contacts between the two components (Fig. 5). Although neighbouring stair-like layers contacting each other via C—H···Ag produce grid-like one-dimensional tunnels with diameters from about 0.6 to 1 nm, AsF6- counter-anions occupy these tunnels, diminishing the gas absorption ability of the solid material. However, ion-exchange from AsF6- anions to other analogues such as PF6- is possible.
Finally, C—H···Ag inter- or intra-molecular interactions were found in only a few silver compounds and act as connectors to link some finite components (e.g. {[AgL2](ClO4)}2, L2 = 9-[3-(2-pyridyl)pyrazol-1-yl]acridine; Ag···H = 2.657–2.706 Å, Ag···C = 3.198–3.231 Å and C—H···Ag = 116.60–117.73°; Clarke et al., 2004; McMorran & Steel, 2002; Liu et al., 2006; Zhao & Mak, 2007). However, to the best of our knowledge, these authors found no C—H···Ag interactions that connect infinite one-dimensional chains or two-dimensional layers of silver coordination polymers to construct higher-dimensional frameworks. This work may therefore provide a new method for the construction of supramolecular high-dimensional frameworks.