research communications
of a cadmium sulfate coordination polymer based on the 3,6-bis(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazine ligand
aThammasat University Research Unit in Multifunctional Crystalline Materials and Applications (TU-MCMA), Faculty of Science and Technology,, Thammasat University, Khlong Luang, Pathum Thani, 12121, Thailand
*Correspondence e-mail: kc@tu.ac.th
The polymeric title compound, poly[aquahemi[μ2-3,6-bis(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazine](μ3-sulfato)cadmium(II)], [Cd(SO4)(C10H8N8)0.5(H2O)]n, (I), represents an example of a three-dimensional coordination polymer resulting from the reaction of CdSO4·8/3H2O with 3,6-bis(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazine (H2bmtz, C10H8N8) under hydrothermal conditions. The CdII atom has a distorted octahedral coordination environment defined by two nitrogen atoms from one H2bmtz ligand, three oxygen atoms from three different sulfate anions, and one oxygen atom from a coordinating water molecule. The 1,4-dihydro-1,2,4,5-tetrazine ring of the H2bmtz ligand is located about an inversion center, with the NH group being equally disordered over two sites. The sulfate anion acts as a μ3-bridging ligand to connect three CdII atoms, resulting in the formation of [Cd(SO4)(H2O)] sheets propagating parallel to the bc plane. Adjacent sheets are interconnected across the H2bmtz ligands, which coordinate the CdII atoms in a bis-bidentate coordination mode, to form a three-dimensional framework structure. The framework is further stabilized by classical O—H⋯O hydrogen bonds involving the coordinating water molecules and the sulfate groups, and by N—H⋯O hydrogen bonds between the disordered tetrazine NH groups and sulfate oxygen atom, along with C—H⋯π and π–π stacking [centroid-to-centroid separation = 3.5954 (15) Å] interactions between parallel pyrimidine rings of the H2bmtz ligand.
Keywords: crystal structure; coordination polymers; cadmium(II); bis-bidentate coordination mode; tetrazine.
CCDC reference: 2004950
1. Chemical context
Coordination polymers (CPs) are a class of organic–inorganic hybrid materials formed from metal ions or metal clusters and organic linkers through covalent bonds. The structural organization of CPs can result in chains, sheets or three-dimensional frameworks (Batten et al., 2009). These hybrid materials have received extensive attention over the past three decades owing to their structural features and useful applications in the fields of gas storage and separation, catalysis, chemical sensing, magnetism or proton conduction (Furukawa et al., 2010; Ye & Johnson, 2016; Espallargas & Coronado, 2018; Xu et al., 2016; Zhang et al., 2017). Nowadays, many multi-dimensional CPs with structural and topological diversity have been synthesized through the tremendous possibilities of choices for building blocks, and some of them seem promising as candidate materials, for instance, in gas purification (Duan et al., 2015). In the context of the crystal engineering of CPs, the most feasible strategy for the construction of such infinite hybrid networks is by the careful selection of metal coordination arrangements and suitable organic linkers. Among the most common ligands, the rigid organic carboxylate- and pyridyl-based ligands have by far been the most widely used to control the structural motifs of these solids (Glöckle et al., 2001).
In this work, to explore the synthesis of novel CPs using 3,6-bis(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazine, C10H8N8 or H2bmtz (Kaim & Fees, 1995; Chainok et al., 2012) as a polydentate nitrogen-donor ligand with cadmium(II) sulfate, a new CP [Cd(SO4)(H2bmtz)0.5(H2O)]n (I) was isolated under hydrothermal conditions. The and supramolecular interactions of (I) are reported herein.
2. Structural commentary
The II cation, one-half of the H2bmtz ligand, one sulfate anion and one coordinating water molecule. The 1,4-dihydro-1,2,4,5-tetrazine ring of the H2bmtz ligand is located about an inversion centre, with the NH group (N4) being equally disordered over two sites. As shown in Fig. 1, the CdII atom exhibits a distorted octahedral [CdN2O4] coordination environment with two nitrogen atoms from the H2bmtz ligand, three oxygen atoms from three different sulfate anions and one oxygen atom from the coordinating water molecule. The bond angles around the central CdII atom range from 69.69 (5) to 168.46 (5)°. The Cd—O and Cd—N bond lengths fall in the range of 2.2321 (12)–2.3790 (13) Å, which is comparable with those of reported cadmium(II) sulfate compounds containing additional nitrogen donor ligands such as [Cd2(SO4)2(C16H12N6)2(H2O)2]·4H2O (GADLON; Harvey et al., 2003), [Cd2(C2H3O2)2(S2O8)(C15H11N2)2(H2O)2]·7H2O (FOMBUF; Díaz de Vivar et al., 2005) and [Cd2(C15H9N9)(H2O)6(SO4)2]·H2O (DIQCOX; Safin et al., 2013). The complete H2bmtz molecule is not planar (r.m.s. deviation = 0.111 Å) with the central six-membered ring of the 1,4-dihydro-1,2,4,5-tetrazine moiety in a twist-boat conformation; the C5—N3—N4Ai—C5i torsion angle is 36.4 (4)° [symmetry code: (i) 2 − x, 1 − y, 1 − z]. The sulfate anion acts as a μ3-bridging ligand to connect three CdII atoms to form a sheet-like structure of [Cd(SO4)(H2O)] units, propagating parallel to the bc plane, Fig. 2. Adjacent sheets are interconnected across the H2bmtz ligands, which exhibit a bis-bidentate coordination mode, giving rise to a three-dimensional framework structure, Fig. 3.
of the title compound consists of one Cd3. Supramolecular features
In the crystal, classical O—H⋯O hydrogen bonds exist between the coordinating water molecules and the sulfate groups, and N—H⋯O hydrogen bonds involving the disordered tetrazine NH group and sulfate oxygen atoms. In this way, rings with R11(8) and R44(16) graph-set motifs are formed, Table 1. Additionally, C—H⋯π [H⋯Cg = 3.34 (2) Å; Cg is the centroid of the pyrimidine ring] and π–π stacking [centroid-to-centroid separation = 3.5954 (15) Å, slippage between parallel pyrimidine rings = 1.131 Å] interactions between the pyrimidine rings of the H2bmtz ligand are also observed, Fig. 4.
4. Database survey
A search of the Cambridge Structural Database (CSD version 5.41, November 2019 update; Groom et al., 2016) gave only two hits for H2bmtz complexes with transition metals ions, viz. with CuI (QORNAM; Glöckle et al., 2001) and AgI (ZASTAQ; Chainok et al., 2012). In these structures, the coordination mode of the H2bmtz ligands is bis-bidentate through nitrogen atoms.
5. Synthesis and crystallization
All reagents were of analytical grade and were used as received without further purification. The ligand 3,6-bis(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazine was synthesized according to a literature method (Kaim & Fees, 1995). A mixture solution of CdSO4·8/3H2O (41.7 mg, 0.2 mmol) and the H2bmtz ligand (36.7 mg, 0.1 mmol) in water (5 ml) was added into a 15 ml Teflon-lined reactor, stirred at room temperature for 10 min, sealed in a stainless steel autoclave and placed in an oven. The mixture was heated to 383 K under autogenous pressure for 48 h, and then cooled down to room temperature. After filtration, brown block-shaped crystals were obtained in 80% yield (33.4 mg) based on the cadmium(II) source.
6. Refinement
Crystal data, data collection and structure . Nitrogen atom N4 of the 1,4-dihydro-1,2,4,5-tetrazine ring was found to be disordered about an inversion centre; restraints (SADI and RIGU with esd 0.001 Å2) were used for its All hydrogen atoms were found in difference-Fourier maps. H atoms attached to C atoms were refined in the riding-model approximation with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C). The H atoms bound to O or N atoms were refined with distance restraints of O—H = 0.84 ± 0.01 Å and N—H = 0.86 ± 0.01 Å and with Uiso(H) = 1.5Ueq(O) and 1.2Ueq(N), respectively.
details are summarized in Table 2
|
Supporting information
CCDC reference: 2004950
https://doi.org/10.1107/S2056989020006830/wm5546sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020006830/wm5546Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989020006830/wm5546Isup3.cdx
Data collection: APEX3 (Bruker, 2016); cell
SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: ShelXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).[Cd(SO4)(C10H8N8)0.5(H2O)] | F(000) = 672 |
Mr = 346.60 | Dx = 2.445 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 9.3000 (3) Å | Cell parameters from 9940 reflections |
b = 7.9798 (2) Å | θ = 3.4–28.4° |
c = 13.2586 (4) Å | µ = 2.56 mm−1 |
β = 106.872 (1)° | T = 296 K |
V = 941.60 (5) Å3 | Block, brown |
Z = 4 | 0.28 × 0.24 × 0.18 mm |
Bruker D8 QUEST CMOS diffractometer | 2357 independent reflections |
Radiation source: sealed x-ray tube | 2338 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
Detector resolution: 7.39 pixels mm-1 | θmax = 28.4°, θmin = 3.2° |
φ and ω scans | h = −12→12 |
Absorption correction: multi-scan (SADABS; Bruker, 2016) | k = −10→10 |
Tmin = 0.660, Tmax = 0.746 | l = −17→17 |
24280 measured reflections |
Refinement on F2 | Hydrogen site location: mixed |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.014 | w = 1/[σ2(Fo2) + (0.0176P)2 + 0.6173P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.037 | (Δ/σ)max = 0.002 |
S = 1.12 | Δρmax = 0.41 e Å−3 |
2357 reflections | Δρmin = −0.37 e Å−3 |
167 parameters | Extinction correction: SHELXL-2018/3 (Sheldrick 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
11 restraints | Extinction coefficient: 0.0013 (3) |
Primary atom site location: dual |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Cd1 | 0.61850 (2) | 0.31497 (2) | 0.37692 (2) | 0.01977 (5) | |
S1 | 0.46994 (4) | 0.71617 (4) | 0.38900 (3) | 0.01921 (8) | |
O1 | 0.40176 (15) | 0.17176 (15) | 0.34420 (10) | 0.0290 (2) | |
H1A | 0.378 (3) | 0.170 (3) | 0.4004 (13) | 0.046 (7)* | |
H1B | 0.408 (3) | 0.0706 (15) | 0.329 (2) | 0.049 (7)* | |
O2 | 0.49134 (16) | 0.55557 (15) | 0.34172 (10) | 0.0389 (3) | |
O3 | 0.61350 (13) | 0.77844 (18) | 0.45697 (10) | 0.0327 (3) | |
O4 | 0.40858 (15) | 0.83595 (14) | 0.30158 (9) | 0.0276 (2) | |
O5 | 0.35993 (14) | 0.70011 (18) | 0.44827 (9) | 0.0338 (3) | |
N1 | 0.81264 (15) | 0.12667 (17) | 0.37110 (10) | 0.0254 (3) | |
N2 | 1.07599 (16) | 0.1093 (2) | 0.39678 (13) | 0.0342 (3) | |
N3 | 0.85731 (15) | 0.44436 (17) | 0.44639 (13) | 0.0321 (3) | |
N4A | 1.1157 (3) | 0.4194 (4) | 0.4718 (3) | 0.0326 (6) | 0.5 |
H4A | 1.180 (2) | 0.345 (3) | 0.5064 (15) | 0.070 (9)* | |
N4B | 1.1132 (3) | 0.3849 (4) | 0.5340 (3) | 0.0320 (6) | 0.5 |
C1 | 0.7954 (2) | −0.0244 (2) | 0.32666 (14) | 0.0337 (4) | |
H1 | 0.699820 | −0.071019 | 0.303463 | 0.040* | |
C2 | 0.9168 (2) | −0.1135 (3) | 0.31425 (17) | 0.0427 (4) | |
H2 | 0.904140 | −0.217907 | 0.281657 | 0.051* | |
C3 | 1.0573 (2) | −0.0420 (3) | 0.35194 (17) | 0.0410 (4) | |
H3 | 1.140880 | −0.100588 | 0.345972 | 0.049* | |
C4 | 0.95337 (18) | 0.18608 (18) | 0.40350 (13) | 0.0243 (3) | |
C5 | 0.97378 (19) | 0.3543 (2) | 0.45278 (17) | 0.0354 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd1 | 0.01945 (7) | 0.02157 (7) | 0.01864 (7) | 0.00090 (3) | 0.00607 (4) | 0.00089 (3) |
S1 | 0.02314 (16) | 0.01938 (15) | 0.01601 (15) | 0.00267 (12) | 0.00708 (12) | 0.00085 (12) |
O1 | 0.0335 (6) | 0.0267 (6) | 0.0300 (6) | −0.0058 (4) | 0.0145 (5) | −0.0068 (4) |
O2 | 0.0544 (8) | 0.0226 (6) | 0.0341 (6) | 0.0142 (5) | 0.0042 (6) | −0.0037 (5) |
O3 | 0.0235 (5) | 0.0464 (7) | 0.0285 (6) | −0.0025 (5) | 0.0081 (5) | −0.0066 (5) |
O4 | 0.0458 (7) | 0.0195 (5) | 0.0182 (5) | 0.0052 (5) | 0.0102 (5) | 0.0032 (4) |
O5 | 0.0249 (6) | 0.0580 (8) | 0.0200 (5) | −0.0031 (5) | 0.0090 (4) | 0.0059 (5) |
N1 | 0.0235 (6) | 0.0253 (6) | 0.0262 (6) | 0.0015 (5) | 0.0053 (5) | −0.0010 (5) |
N2 | 0.0250 (6) | 0.0319 (7) | 0.0456 (8) | 0.0029 (6) | 0.0101 (6) | −0.0042 (6) |
N3 | 0.0208 (6) | 0.0213 (6) | 0.0537 (9) | −0.0026 (5) | 0.0101 (6) | −0.0076 (6) |
N4A | 0.0192 (11) | 0.0255 (14) | 0.0529 (19) | −0.0017 (10) | 0.0102 (12) | −0.0135 (14) |
N4B | 0.0227 (12) | 0.0210 (13) | 0.0506 (18) | −0.0004 (10) | 0.0079 (11) | −0.0084 (13) |
C1 | 0.0292 (8) | 0.0321 (8) | 0.0356 (9) | −0.0019 (7) | 0.0025 (7) | −0.0077 (7) |
C2 | 0.0421 (10) | 0.0341 (9) | 0.0480 (11) | 0.0047 (8) | 0.0067 (8) | −0.0178 (8) |
C3 | 0.0331 (9) | 0.0400 (10) | 0.0498 (11) | 0.0091 (8) | 0.0119 (8) | −0.0117 (8) |
C4 | 0.0235 (7) | 0.0233 (7) | 0.0262 (7) | 0.0011 (5) | 0.0072 (6) | 0.0009 (5) |
C5 | 0.0203 (7) | 0.0228 (7) | 0.0613 (11) | −0.0022 (6) | 0.0087 (7) | −0.0069 (7) |
Cd1—O1 | 2.2472 (12) | N2—C4 | 1.320 (2) |
Cd1—O2 | 2.2321 (12) | N3—N4Aiii | 1.505 (3) |
Cd1—O4i | 2.3122 (11) | N3—N4Biii | 1.399 (3) |
Cd1—O5ii | 2.2708 (12) | N3—C5 | 1.282 (2) |
Cd1—N1 | 2.3674 (13) | N4A—H4A | 0.871 (10) |
Cd1—N3 | 2.3790 (13) | N4A—C5 | 1.372 (3) |
S1—O2 | 1.4653 (12) | N4B—H4A | 0.866 (10) |
S1—O3 | 1.4640 (12) | N4B—C5 | 1.445 (3) |
S1—O4 | 1.4828 (11) | C1—H1 | 0.9300 |
S1—O5 | 1.4654 (12) | C1—C2 | 1.384 (3) |
O1—H1A | 0.835 (10) | C2—H2 | 0.9300 |
O1—H1B | 0.839 (10) | C2—C3 | 1.379 (3) |
N1—C1 | 1.331 (2) | C3—H3 | 0.9300 |
N1—C4 | 1.340 (2) | C4—C5 | 1.481 (2) |
N2—C3 | 1.335 (2) | ||
O1—Cd1—O4i | 90.81 (5) | C4—N2—C3 | 116.51 (15) |
O1—Cd1—O5ii | 88.77 (5) | N4Aiii—N3—Cd1 | 122.32 (13) |
O1—Cd1—N1 | 108.71 (5) | N4Biii—N3—Cd1 | 127.25 (15) |
O1—Cd1—N3 | 168.46 (5) | C5—N3—Cd1 | 117.26 (11) |
O2—Cd1—O1 | 90.34 (5) | C5—N3—N4Aiii | 113.35 (17) |
O2—Cd1—O4i | 80.21 (5) | C5—N3—N4Biii | 114.67 (17) |
O2—Cd1—O5ii | 98.25 (5) | N3iii—N4A—H4A | 99.5 (18) |
O2—Cd1—N1 | 154.41 (5) | C5—N4A—N3iii | 110.9 (2) |
O2—Cd1—N3 | 94.94 (5) | C5—N4A—H4A | 108.3 (19) |
O4i—Cd1—N1 | 82.54 (5) | N3iii—N4B—H4A | 108.1 (19) |
O4i—Cd1—N3 | 100.19 (5) | N3iii—N4B—C5 | 112.9 (2) |
O5ii—Cd1—O4i | 178.41 (4) | C5—N4B—H4A | 102.7 (18) |
O5ii—Cd1—N1 | 99.05 (5) | N1—C1—H1 | 119.3 |
O5ii—Cd1—N3 | 80.32 (5) | N1—C1—C2 | 121.38 (16) |
N1—Cd1—N3 | 69.69 (5) | C2—C1—H1 | 119.3 |
O2—S1—O4 | 107.38 (7) | C1—C2—H2 | 121.2 |
O2—S1—O5 | 110.83 (9) | C3—C2—C1 | 117.63 (17) |
O3—S1—O2 | 110.33 (8) | C3—C2—H2 | 121.2 |
O3—S1—O4 | 109.74 (8) | N2—C3—C2 | 121.52 (17) |
O3—S1—O5 | 110.69 (7) | N2—C3—H3 | 119.2 |
O5—S1—O4 | 107.78 (7) | C2—C3—H3 | 119.2 |
Cd1—O1—H1A | 106.8 (18) | N1—C4—C5 | 116.76 (14) |
Cd1—O1—H1B | 114.6 (17) | N2—C4—N1 | 126.64 (15) |
H1A—O1—H1B | 105 (2) | N2—C4—C5 | 116.60 (15) |
S1—O2—Cd1 | 142.41 (8) | N3—C5—N4A | 123.30 (19) |
S1—O4—Cd1iv | 131.02 (7) | N3—C5—N4B | 120.8 (2) |
S1—O5—Cd1ii | 133.11 (8) | N3—C5—C4 | 118.78 (15) |
C1—N1—Cd1 | 126.47 (11) | N4A—C5—C4 | 114.68 (18) |
C1—N1—C4 | 116.31 (14) | N4B—C5—C4 | 117.02 (18) |
C4—N1—Cd1 | 116.63 (10) | ||
Cd1—N1—C1—C2 | 170.31 (15) | N2—C4—C5—N3 | 169.24 (18) |
Cd1—N1—C4—N2 | −172.52 (14) | N2—C4—C5—N4A | 8.9 (3) |
Cd1—N1—C4—C5 | 8.10 (19) | N2—C4—C5—N4B | −31.3 (3) |
Cd1—N3—C5—N4A | 167.1 (2) | N3iii—N4A—C5—N3 | 40.7 (4) |
Cd1—N3—C5—N4B | −150.1 (2) | N3iii—N4A—C5—C4 | −160.0 (2) |
Cd1—N3—C5—C4 | 8.5 (2) | N3iii—N4B—C5—N3 | −38.9 (4) |
O2—S1—O4—Cd1iv | −10.01 (13) | N3iii—N4B—C5—C4 | 162.2 (2) |
O2—S1—O5—Cd1ii | 103.95 (11) | N4Aiii—N3—C5—N4A | −41.6 (4) |
O3—S1—O2—Cd1 | 38.91 (17) | N4Aiii—N3—C5—C4 | 159.9 (2) |
O3—S1—O4—Cd1iv | 109.93 (10) | N4Biii—N3—C5—N4B | 39.5 (4) |
O3—S1—O5—Cd1ii | −18.81 (14) | N4Biii—N3—C5—C4 | −161.9 (2) |
O4—S1—O2—Cd1 | 158.47 (14) | C1—N1—C4—N2 | −0.8 (3) |
O4—S1—O5—Cd1ii | −138.82 (10) | C1—N1—C4—C5 | 179.83 (16) |
O5—S1—O2—Cd1 | −84.06 (16) | C1—C2—C3—N2 | −1.5 (3) |
O5—S1—O4—Cd1iv | −129.45 (10) | C3—N2—C4—N1 | 0.9 (3) |
N1—C1—C2—C3 | 1.5 (3) | C3—N2—C4—C5 | −179.74 (18) |
N1—C4—C5—N3 | −11.3 (3) | C4—N1—C1—C2 | −0.5 (3) |
N1—C4—C5—N4A | −171.7 (2) | C4—N2—C3—C2 | 0.3 (3) |
N1—C4—C5—N4B | 148.1 (2) |
Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) −x+1, −y+1, −z+1; (iii) −x+2, −y+1, −z+1; (iv) −x+1, y+1/2, −z+1/2. |
Cg1 is the centroid of the N1/N2/C1–C4 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···O3ii | 0.84 (2) | 1.92 (2) | 2.710 (2) | 159 (2) |
O1—H1B···O4v | 0.84 (2) | 1.91 (2) | 2.743 (2) | 174 (3) |
N4A—H4A···O3iii | 0.87 (2) | 2.09 (2) | 2.889 (3) | 153 (2) |
N4B—H4A···O3iii | 0.87 (2) | 2.09 (2) | 2.828 (3) | 143 (2) |
C2—H2···Cg1vi | 0.93 | 3.34 (2) | 4.091 (3) | 140 (2) |
Symmetry codes: (ii) −x+1, −y+1, −z+1; (iii) −x+2, −y+1, −z+1; (v) x, y−1, z; (vi) −x+2, y−1/2, −z+1/2. |
Acknowledgements
The authors thank the Faculty of Science and Technology, Thammasat University, for funds to purchase the X-ray diffractometer.
Funding information
Funding for this research was provided by: Thailand Research Fund (contract No. RSA5780056 to KC); The Research Professional Development Project Under the Science Achievement Scholarship of Thailand (SAST) (award to SJ).
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