Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807019836/ci2367sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807019836/ci2367Isup2.hkl |
CCDC reference: 646660
A mixture of ZnCO3 (0.4180 g, 3.33 mmol) and 2-chlorobenzoic acid (1.0438 g, 3.33 mmol) in ethanol (50 ml) was stirred at room temperature for 1 h and then filtered. An ethanol solution (50 ml) of methyl-3-pyridylcarbamate (1.0143 g, 3.33 mmol) was added to the filtrate and the mixture was stirred for 3 h. The resulting clear solution was allowed to stand in air at room temperature for two weeks, yielding colourless crystals of (I). The crystals were separated and dried at ambient temperature.
H atoms were placed in calculated positions [N–H = 0.86 Å and C–H = 0.93 (aromatic) or 0.96 Å (methyl)] and refined using a riding model, with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C).
Compound (I) is a mononuclear zinc(II) compound (Fig. 1). The ZnII atom exists in a pseudo-octahedral coordination environment, created by two pyridine N atoms from two methyl-3-pyridylcarbamate (mpc) ligands and four O atoms from two bidentate 2-chlorobenzoate anions. But a tetrahedral arrangement is found for the ZnII atoms in related structures, viz. [Zn(benzoato)2(mpc)2] (Zeleňák et al., 2004) and [Zn(cinnamato)2(mpc)] (Zeleňák et al., 2007). The mean Zn–N distances of 2.032 Å (in the former) and 2.021 Å (in the latter) are shorter than that in compound (I) (2.181 Å), as expected for a tetrahedral arrangement. The Zn—O distances are in the range 2.0484 (16)–2.380 (2) Å, and the Zn—N and Zn—Cl distances are 2.1012 (18) and 2.546 (2) Å, respectively.
In the crystal structure of (I), the molecules are linked by N2–H2···O2ii and C8–H8···Clii [symmetry code: (ii) x, 1/2 - y, 1/2 + z] hydrogen bonds (Table 1), forming a chain along the c axis (Fig. 2).
The ZnII atom adopts a tetrahedral geometry in related complexes with methyl N-(3-pyridyl)carbamate ligands (Zeleňák et al., 2004, 2007).
Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: enCIFer (Allen et al., 2004).
[Zn(C7H4ClO2)2(C7H8N2O2)2] | F(000) = 1392 |
Mr = 680.78 | Dx = 1.574 Mg m−3 |
Orthorhombic, Pccn | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2ab 2ac | Cell parameters from 25 reflections |
a = 15.444 (3) Å | θ = 4.5–8.6° |
b = 13.650 (3) Å | µ = 1.10 mm−1 |
c = 13.627 (3) Å | T = 293 K |
V = 2872.7 (10) Å3 | Prism, colourless |
Z = 4 | 0.70 × 0.50 × 0.40 mm |
Siemens P4 diffractometer | 2566 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.021 |
Graphite monochromator | θmax = 28.0°, θmin = 2.5° |
2θ/ω scans | h = −1→20 |
Absorption correction: ψ scan (XEMP; Siemens, 1994) | k = −1→18 |
Tmin = 0.304, Tmax = 0.339 | l = −1→18 |
4275 measured reflections | 3 standard reflections every 97 reflections |
3429 independent reflections | intensity decay: 4.3% |
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)] = 0.037 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0406P)2 + 0.9964P] where P = (Fo2 + 2Fc2)/3 |
3429 reflections | (Δ/σ)max = 0.001 |
196 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.36 e Å−3 |
[Zn(C7H4ClO2)2(C7H8N2O2)2] | V = 2872.7 (10) Å3 |
Mr = 680.78 | Z = 4 |
Orthorhombic, Pccn | Mo Kα radiation |
a = 15.444 (3) Å | µ = 1.10 mm−1 |
b = 13.650 (3) Å | T = 293 K |
c = 13.627 (3) Å | 0.70 × 0.50 × 0.40 mm |
Siemens P4 diffractometer | 2566 reflections with I > 2σ(I) |
Absorption correction: ψ scan (XEMP; Siemens, 1994) | Rint = 0.021 |
Tmin = 0.304, Tmax = 0.339 | 3 standard reflections every 97 reflections |
4275 measured reflections | intensity decay: 4.3% |
3429 independent reflections |
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.27 e Å−3 |
3429 reflections | Δρmin = −0.36 e Å−3 |
196 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Zn | 0.2500 | 0.2500 | 0.00830 (3) | 0.04173 (11) | |
Cl | 0.02319 (4) | 0.17755 (6) | −0.27367 (6) | 0.0697 (2) | |
N1 | 0.30551 (11) | 0.34776 (13) | 0.10944 (13) | 0.0420 (4) | |
N2 | 0.22484 (13) | 0.47062 (13) | 0.32673 (15) | 0.0503 (5) | |
H2 | 0.1861 | 0.4281 | 0.3423 | 0.060* | |
O1 | 0.14614 (11) | 0.33727 (13) | −0.02481 (14) | 0.0577 (4) | |
O2 | 0.14705 (12) | 0.20595 (14) | −0.11392 (15) | 0.0677 (5) | |
O3 | 0.27541 (12) | 0.62242 (13) | 0.36654 (14) | 0.0632 (5) | |
O4 | 0.15579 (14) | 0.55887 (13) | 0.43625 (14) | 0.0683 (5) | |
C1 | 0.11059 (14) | 0.28121 (17) | −0.08633 (17) | 0.0458 (5) | |
C2 | 0.02036 (13) | 0.30729 (14) | −0.11921 (16) | 0.0402 (4) | |
C3 | −0.02401 (14) | 0.26336 (16) | −0.19616 (17) | 0.0450 (5) | |
C4 | −0.10918 (16) | 0.2880 (2) | −0.21635 (19) | 0.0567 (6) | |
H4 | −0.1382 | 0.2570 | −0.2675 | 0.068* | |
C5 | −0.15084 (17) | 0.3575 (2) | −0.1616 (2) | 0.0647 (7) | |
H5 | −0.2082 | 0.3732 | −0.1752 | 0.078* | |
C6 | −0.10790 (17) | 0.4042 (2) | −0.0863 (2) | 0.0643 (7) | |
H6 | −0.1356 | 0.4525 | −0.0499 | 0.077* | |
C7 | −0.02320 (15) | 0.37853 (18) | −0.06538 (18) | 0.0519 (5) | |
H7 | 0.0053 | 0.4097 | −0.0140 | 0.062* | |
C8 | 0.25616 (14) | 0.37803 (15) | 0.18363 (16) | 0.0423 (4) | |
H8 | 0.2005 | 0.3525 | 0.1891 | 0.051* | |
C9 | 0.28322 (14) | 0.44532 (15) | 0.25299 (15) | 0.0411 (4) | |
C10 | 0.36653 (15) | 0.48203 (17) | 0.24529 (17) | 0.0494 (5) | |
H10 | 0.3877 | 0.5266 | 0.2910 | 0.059* | |
C11 | 0.41724 (15) | 0.45099 (18) | 0.16834 (19) | 0.0539 (6) | |
H11 | 0.4732 | 0.4751 | 0.1612 | 0.065* | |
C12 | 0.38551 (14) | 0.38477 (18) | 0.10245 (17) | 0.0502 (5) | |
H12 | 0.4207 | 0.3647 | 0.0509 | 0.060* | |
C13 | 0.22424 (16) | 0.55699 (17) | 0.37586 (17) | 0.0492 (5) | |
C14 | 0.1445 (2) | 0.6486 (2) | 0.4903 (2) | 0.0798 (9) | |
H14A | 0.1280 | 0.7000 | 0.4461 | 0.120* | |
H14B | 0.1979 | 0.6656 | 0.5220 | 0.120* | |
H14C | 0.1001 | 0.6398 | 0.5388 | 0.120* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Zn | 0.04048 (17) | 0.04280 (18) | 0.0419 (2) | 0.00580 (14) | 0.000 | 0.000 |
Cl | 0.0637 (4) | 0.0734 (4) | 0.0720 (4) | −0.0131 (3) | 0.0083 (3) | −0.0261 (4) |
N1 | 0.0427 (8) | 0.0407 (9) | 0.0427 (10) | 0.0003 (7) | −0.0003 (8) | −0.0004 (7) |
N2 | 0.0636 (11) | 0.0395 (9) | 0.0477 (11) | −0.0067 (8) | 0.0129 (9) | −0.0020 (8) |
O1 | 0.0516 (9) | 0.0575 (10) | 0.0642 (11) | 0.0012 (8) | −0.0142 (8) | 0.0015 (8) |
O2 | 0.0678 (11) | 0.0697 (12) | 0.0656 (12) | 0.0302 (10) | −0.0050 (9) | −0.0042 (10) |
O3 | 0.0788 (12) | 0.0477 (9) | 0.0632 (11) | −0.0113 (9) | 0.0033 (9) | −0.0093 (8) |
O4 | 0.0933 (13) | 0.0544 (10) | 0.0572 (11) | −0.0041 (10) | 0.0267 (10) | −0.0112 (9) |
C1 | 0.0470 (11) | 0.0482 (11) | 0.0422 (12) | 0.0033 (10) | 0.0020 (9) | 0.0115 (9) |
C2 | 0.0443 (10) | 0.0386 (10) | 0.0378 (11) | 0.0021 (8) | 0.0008 (8) | 0.0102 (8) |
C3 | 0.0458 (11) | 0.0465 (12) | 0.0428 (11) | −0.0061 (9) | 0.0028 (9) | 0.0082 (9) |
C4 | 0.0503 (12) | 0.0734 (16) | 0.0463 (13) | −0.0089 (12) | −0.0075 (11) | 0.0143 (12) |
C5 | 0.0470 (12) | 0.0817 (19) | 0.0653 (17) | 0.0114 (13) | −0.0039 (12) | 0.0221 (15) |
C6 | 0.0609 (15) | 0.0689 (16) | 0.0633 (16) | 0.0260 (13) | 0.0045 (13) | 0.0061 (13) |
C7 | 0.0551 (13) | 0.0530 (13) | 0.0477 (13) | 0.0085 (11) | −0.0024 (10) | 0.0003 (10) |
C8 | 0.0417 (10) | 0.0370 (9) | 0.0481 (11) | −0.0023 (8) | 0.0017 (10) | 0.0004 (9) |
C9 | 0.0497 (10) | 0.0329 (9) | 0.0406 (11) | 0.0005 (8) | 0.0009 (9) | 0.0072 (9) |
C10 | 0.0540 (12) | 0.0459 (12) | 0.0484 (13) | −0.0060 (10) | −0.0070 (10) | −0.0027 (10) |
C11 | 0.0428 (11) | 0.0586 (14) | 0.0601 (15) | −0.0090 (10) | −0.0009 (10) | −0.0018 (12) |
C12 | 0.0437 (11) | 0.0585 (13) | 0.0484 (13) | −0.0012 (10) | 0.0032 (10) | 0.0003 (11) |
C13 | 0.0665 (13) | 0.0432 (11) | 0.0379 (11) | 0.0005 (10) | 0.0013 (10) | 0.0025 (9) |
C14 | 0.104 (2) | 0.0697 (18) | 0.0658 (19) | 0.0088 (17) | 0.0153 (17) | −0.0246 (15) |
Zn—O1 | 2.0484 (16) | C2—C7 | 1.391 (3) |
Zn—O1i | 2.0484 (16) | C3—C4 | 1.385 (3) |
Zn—N1 | 2.1012 (18) | C4—C5 | 1.368 (4) |
Zn—N1i | 2.1012 (18) | C4—H4 | 0.93 |
Zn—O2 | 2.380 (2) | C5—C6 | 1.378 (4) |
Zn—O2i | 2.380 (2) | C5—H5 | 0.93 |
Zn—C1i | 2.546 (2) | C6—C7 | 1.384 (3) |
Cl—C3 | 1.737 (2) | C6—H6 | 0.93 |
N1—C8 | 1.332 (3) | C7—H7 | 0.93 |
N1—C12 | 1.338 (3) | C8—C9 | 1.383 (3) |
N2—C13 | 1.356 (3) | C8—H8 | 0.93 |
N2—C9 | 1.394 (3) | C9—C10 | 1.385 (3) |
N2—H2 | 0.86 | C10—C11 | 1.376 (3) |
O1—C1 | 1.261 (3) | C10—H10 | 0.93 |
O2—C1 | 1.230 (3) | C11—C12 | 1.365 (3) |
O3—C13 | 1.199 (3) | C11—H11 | 0.93 |
O4—C13 | 1.340 (3) | C12—H12 | 0.93 |
O4—C14 | 1.439 (3) | C14—H14A | 0.96 |
C1—C2 | 1.506 (3) | C14—H14B | 0.96 |
C2—C3 | 1.389 (3) | C14—H14C | 0.96 |
O1—Zn—O1i | 154.55 (11) | C2—C3—Cl | 122.89 (17) |
O1—Zn—N1 | 95.43 (7) | C5—C4—C3 | 120.4 (2) |
O1i—Zn—N1 | 101.20 (7) | C5—C4—H4 | 119.8 |
O1—Zn—N1i | 101.20 (7) | C3—C4—H4 | 119.8 |
O1i—Zn—N1i | 95.43 (7) | C4—C5—C6 | 120.0 (2) |
N1—Zn—N1i | 98.02 (10) | C4—C5—H5 | 120.0 |
O1—Zn—O2 | 57.97 (6) | C6—C5—H5 | 120.0 |
O1i—Zn—O2 | 102.83 (7) | C5—C6—C7 | 119.4 (3) |
N1—Zn—O2 | 153.14 (6) | C5—C6—H6 | 120.3 |
N1i—Zn—O2 | 91.49 (7) | C7—C6—H6 | 120.3 |
O1—Zn—O2i | 102.83 (7) | C6—C7—C2 | 121.7 (2) |
O1i—Zn—O2i | 57.97 (6) | C6—C7—H7 | 119.2 |
N1—Zn—O2i | 91.49 (7) | C2—C7—H7 | 119.2 |
N1i—Zn—O2i | 153.14 (6) | N1—C8—C9 | 123.51 (19) |
O2—Zn—O2i | 91.17 (10) | N1—C8—H8 | 118.2 |
O1—Zn—C1i | 130.40 (8) | C9—C8—H8 | 118.2 |
O1i—Zn—C1i | 29.39 (7) | C8—C9—C10 | 118.0 (2) |
N1—Zn—C1i | 95.36 (7) | C8—C9—N2 | 117.5 (2) |
N1i—Zn—C1i | 124.83 (7) | C10—C9—N2 | 124.5 (2) |
O2—Zn—C1i | 99.69 (7) | C11—C10—C9 | 118.4 (2) |
O2i—Zn—C1i | 28.68 (7) | C11—C10—H10 | 120.8 |
C8—N1—C12 | 117.73 (19) | C9—C10—H10 | 120.8 |
C8—N1—Zn | 117.48 (14) | C12—C11—C10 | 120.1 (2) |
C12—N1—Zn | 124.73 (15) | C12—C11—H11 | 120.0 |
C13—N2—C9 | 125.2 (2) | C10—C11—H11 | 120.0 |
C13—N2—H2 | 117.4 | N1—C12—C11 | 122.3 (2) |
C9—N2—H2 | 117.4 | N1—C12—H12 | 118.8 |
C1—O1—Zn | 97.73 (14) | C11—C12—H12 | 118.8 |
C1—O2—Zn | 83.16 (15) | O3—C13—O4 | 124.8 (2) |
C13—O4—C14 | 115.2 (2) | O3—C13—N2 | 126.2 (2) |
O2—C1—O1 | 120.7 (2) | O4—C13—N2 | 109.0 (2) |
O2—C1—C2 | 122.0 (2) | O4—C14—H14A | 109.5 |
O1—C1—C2 | 117.2 (2) | O4—C14—H14B | 109.5 |
C3—C2—C7 | 117.46 (19) | H14A—C14—H14B | 109.5 |
C3—C2—C1 | 125.4 (2) | O4—C14—H14C | 109.5 |
C7—C2—C1 | 117.1 (2) | H14A—C14—H14C | 109.5 |
C4—C3—C2 | 120.9 (2) | H14B—C14—H14C | 109.5 |
C4—C3—Cl | 116.18 (19) | ||
O1—Zn—N1—C8 | 55.12 (16) | O2—C1—C2—C7 | 163.7 (2) |
O1i—Zn—N1—C8 | −144.24 (15) | O1—C1—C2—C7 | −12.7 (3) |
N1i—Zn—N1—C8 | −47.03 (13) | C7—C2—C3—C4 | −1.8 (3) |
O2—Zn—N1—C8 | 62.6 (2) | C1—C2—C3—C4 | 175.5 (2) |
O2i—Zn—N1—C8 | 158.16 (15) | C7—C2—C3—Cl | 176.85 (17) |
C1i—Zn—N1—C8 | −173.37 (15) | C1—C2—C3—Cl | −5.9 (3) |
O1—Zn—N1—C12 | −122.03 (18) | C2—C3—C4—C5 | 1.1 (3) |
O1i—Zn—N1—C12 | 38.62 (19) | Cl—C3—C4—C5 | −177.63 (19) |
N1i—Zn—N1—C12 | 135.8 (2) | C3—C4—C5—C6 | 0.6 (4) |
O2—Zn—N1—C12 | −114.5 (2) | C4—C5—C6—C7 | −1.5 (4) |
O2i—Zn—N1—C12 | −18.99 (18) | C5—C6—C7—C2 | 0.7 (4) |
C1i—Zn—N1—C12 | 9.49 (19) | C3—C2—C7—C6 | 0.9 (3) |
O1i—Zn—O1—C1 | 48.91 (13) | C1—C2—C7—C6 | −176.6 (2) |
N1—Zn—O1—C1 | 179.75 (14) | C12—N1—C8—C9 | 0.1 (3) |
N1i—Zn—O1—C1 | −80.94 (15) | Zn—N1—C8—C9 | −177.22 (16) |
O2—Zn—O1—C1 | 3.74 (13) | N1—C8—C9—C10 | −0.9 (3) |
O2i—Zn—O1—C1 | 86.97 (15) | N1—C8—C9—N2 | 179.92 (19) |
C1i—Zn—O1—C1 | 77.97 (19) | C13—N2—C9—C8 | −153.2 (2) |
O1—Zn—O2—C1 | −3.83 (13) | C13—N2—C9—C10 | 27.6 (4) |
O1i—Zn—O2—C1 | −165.62 (14) | C8—C9—C10—C11 | 1.1 (3) |
N1—Zn—O2—C1 | −12.6 (2) | N2—C9—C10—C11 | −179.7 (2) |
N1i—Zn—O2—C1 | 98.47 (15) | C9—C10—C11—C12 | −0.7 (4) |
O2i—Zn—O2—C1 | −108.26 (15) | C8—N1—C12—C11 | 0.3 (3) |
C1i—Zn—O2—C1 | −135.80 (13) | Zn—N1—C12—C11 | 177.46 (18) |
Zn—O2—C1—O1 | 6.1 (2) | C10—C11—C12—N1 | 0.0 (4) |
Zn—O2—C1—C2 | −170.09 (19) | C14—O4—C13—O3 | 1.7 (4) |
Zn—O1—C1—O2 | −7.2 (2) | C14—O4—C13—N2 | −177.3 (2) |
Zn—O1—C1—C2 | 169.25 (16) | C9—N2—C13—O3 | −3.4 (4) |
O2—C1—C2—C3 | −13.6 (3) | C9—N2—C13—O4 | 175.6 (2) |
O1—C1—C2—C3 | 170.0 (2) |
Symmetry code: (i) −x+1/2, −y+1/2, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···O2ii | 0.86 | 2.02 | 2.812 (3) | 153 |
C8—H8···Clii | 0.93 | 2.82 | 3.723 (2) | 165 |
Symmetry code: (ii) x, −y+1/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Zn(C7H4ClO2)2(C7H8N2O2)2] |
Mr | 680.78 |
Crystal system, space group | Orthorhombic, Pccn |
Temperature (K) | 293 |
a, b, c (Å) | 15.444 (3), 13.650 (3), 13.627 (3) |
V (Å3) | 2872.7 (10) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.10 |
Crystal size (mm) | 0.70 × 0.50 × 0.40 |
Data collection | |
Diffractometer | Siemens P4 |
Absorption correction | ψ scan (XEMP; Siemens, 1994) |
Tmin, Tmax | 0.304, 0.339 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4275, 3429, 2566 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.661 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.096, 1.02 |
No. of reflections | 3429 |
No. of parameters | 196 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.27, −0.36 |
Computer programs: XSCANS (Siemens, 1994), XSCANS, SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), enCIFer (Allen et al., 2004).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···O2i | 0.86 | 2.02 | 2.812 (3) | 153 |
C8—H8···Cli | 0.93 | 2.82 | 3.723 (2) | 165 |
Symmetry code: (i) x, −y+1/2, z+1/2. |
Compound (I) is a mononuclear zinc(II) compound (Fig. 1). The ZnII atom exists in a pseudo-octahedral coordination environment, created by two pyridine N atoms from two methyl-3-pyridylcarbamate (mpc) ligands and four O atoms from two bidentate 2-chlorobenzoate anions. But a tetrahedral arrangement is found for the ZnII atoms in related structures, viz. [Zn(benzoato)2(mpc)2] (Zeleňák et al., 2004) and [Zn(cinnamato)2(mpc)] (Zeleňák et al., 2007). The mean Zn–N distances of 2.032 Å (in the former) and 2.021 Å (in the latter) are shorter than that in compound (I) (2.181 Å), as expected for a tetrahedral arrangement. The Zn—O distances are in the range 2.0484 (16)–2.380 (2) Å, and the Zn—N and Zn—Cl distances are 2.1012 (18) and 2.546 (2) Å, respectively.
In the crystal structure of (I), the molecules are linked by N2–H2···O2ii and C8–H8···Clii [symmetry code: (ii) x, 1/2 - y, 1/2 + z] hydrogen bonds (Table 1), forming a chain along the c axis (Fig. 2).