In the title compound, [Ca(C
9H
11N
6O
5)
2(H
2O)
3], the Ca atom lies on a twofold rotation axis in
C2/
c and the three water molecules are all disordered, each over two sites having equal occupancy. The anion acts as a bridging ligand between pairs of Ca sites on the same twofold axis, thus forming a one-dimensional coordination polymer, with the chains lying along the twofold axes. These chains are linked by multiple O—H
O and N—H
O hydrogen bonds into a single three-dimensional framework.
Supporting information
CCDC reference: 166962
Crystals of compound (II) were obtained adventitiously during preparation of the
potassium salt derived from the ligand HL, (I) (Low, Arranz et al.,
2001).
Compound (II) crystallized in the monoclinic system. Space groups Cc and
C2/c were permitted by the systematic absences;
C2/c was chosen and confirmed by the successful structure
analysis. H atoms were treated as riding atoms with C—H distances of 0.98
(CH2) or 0.99 Å (CH3), and an N—H distance of 0.88 Å. Water
molecules were initially handled via DFIX with an O—H distance of
0.87 (3) Å, and after this refinement had fully converged, the H atoms were
treated as riding atoms using AFIX.
Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) PRPKAPPA (Ferguson, 1999).
Triaqua-bis[
N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-
yl)glycylglycinato]calcium
top
Crystal data top
[Ca(C9H11N6O5)2(H2O)3] | F(000) = 1376 |
Mr = 660.60 | Dx = 1.708 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 12.7815 (7) Å | Cell parameters from 2553 reflections |
b = 7.7010 (7) Å | θ = 1.6–26.3° |
c = 26.271 (2) Å | µ = 0.34 mm−1 |
β = 96.418 (5)° | T = 150 K |
V = 2569.7 (4) Å3 | Plate, colourless |
Z = 4 | 0.15 × 0.08 × 0.01 mm |
Data collection top
KappaCCD diffractometer | 2553 independent reflections |
Radiation source: fine-focus sealed X-ray tube | 1641 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.090 |
ϕ scans, and ω scans with κ offsets | θmax = 26.3°, θmin = 1.6° |
Absorption correction: multi-scan )SORTAV; Blessing, 1995, 1997) | h = −15→15 |
Tmin = 0.951, Tmax = 0.997 | k = −9→9 |
17345 measured reflections | l = −32→32 |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.135 | H-atom parameters constrained |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0683P)2 + 1.8308P] where P = (Fo2 + 2Fc2)/3 |
2553 reflections | (Δ/σ)max < 0.001 |
214 parameters | Δρmax = 0.32 e Å−3 |
0 restraints | Δρmin = −0.36 e Å−3 |
Crystal data top
[Ca(C9H11N6O5)2(H2O)3] | V = 2569.7 (4) Å3 |
Mr = 660.60 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 12.7815 (7) Å | µ = 0.34 mm−1 |
b = 7.7010 (7) Å | T = 150 K |
c = 26.271 (2) Å | 0.15 × 0.08 × 0.01 mm |
β = 96.418 (5)° | |
Data collection top
KappaCCD diffractometer | 2553 independent reflections |
Absorption correction: multi-scan )SORTAV; Blessing, 1995, 1997) | 1641 reflections with I > 2σ(I) |
Tmin = 0.951, Tmax = 0.997 | Rint = 0.090 |
17345 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.135 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.32 e Å−3 |
2553 reflections | Δρmin = −0.36 e Å−3 |
214 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ca1 | 0.5000 | 0.26170 (14) | 0.2500 | 0.0340 (3) | |
N1 | 0.71309 (17) | 0.0713 (3) | 0.04356 (9) | 0.0232 (6) | |
C2 | 0.80029 (19) | 0.0093 (4) | 0.07061 (11) | 0.0211 (6) | |
N21 | 0.81256 (17) | 0.0356 (3) | 0.12074 (9) | 0.0235 (6) | |
H21 | 0.8675 | −0.0102 | 0.1391 | 0.028* | |
O21 | 0.57497 (16) | 0.1272 (3) | 0.18061 (9) | 0.0366 (6) | |
C21 | 0.7382 (2) | 0.1377 (4) | 0.14670 (11) | 0.0247 (7) | |
H21A | 0.7176 | 0.2406 | 0.1253 | 0.030* | |
H21B | 0.7752 | 0.1804 | 0.1794 | 0.030* | |
N22 | 0.62534 (18) | −0.1190 (3) | 0.14391 (9) | 0.0250 (6) | |
H22A | 0.6735 | −0.1674 | 0.1271 | 0.030* | |
C22 | 0.6389 (2) | 0.0455 (4) | 0.15817 (11) | 0.0235 (7) | |
C23 | 0.5362 (2) | −0.2237 (4) | 0.15430 (12) | 0.0280 (7) | |
H23A | 0.5035 | −0.2745 | 0.1217 | 0.034* | |
H23B | 0.4832 | −0.1477 | 0.1678 | 0.034* | |
C24 | 0.5645 (2) | −0.3702 (4) | 0.19252 (11) | 0.0239 (7) | |
O22 | 0.64762 (16) | −0.3587 (3) | 0.22229 (9) | 0.0432 (6) | |
O23 | 0.49875 (14) | −0.4923 (3) | 0.19159 (7) | 0.0271 (5) | |
N3 | 0.87758 (16) | −0.0826 (3) | 0.04927 (9) | 0.0207 (5) | |
C3 | 0.9703 (2) | −0.1513 (4) | 0.08167 (11) | 0.0282 (7) | |
H3A | 1.0202 | −0.0568 | 0.0908 | 0.042* | |
H3B | 1.0043 | −0.2409 | 0.0628 | 0.042* | |
H3C | 0.9478 | −0.2019 | 0.1129 | 0.042* | |
C4 | 0.8704 (2) | −0.1138 (4) | −0.00318 (11) | 0.0225 (7) | |
O4 | 0.94132 (14) | −0.1910 (3) | −0.02184 (8) | 0.0281 (5) | |
C5 | 0.7752 (2) | −0.0524 (4) | −0.03337 (11) | 0.0210 (6) | |
N5 | 0.76720 (18) | −0.0941 (3) | −0.08314 (9) | 0.0274 (6) | |
O5 | 0.68578 (15) | −0.0401 (3) | −0.11212 (8) | 0.0350 (6) | |
C6 | 0.6993 (2) | 0.0414 (4) | −0.00688 (11) | 0.0222 (6) | |
N6 | 0.61208 (17) | 0.0987 (3) | −0.03334 (10) | 0.0300 (6) | |
H6A | 0.5649 | 0.1548 | −0.0177 | 0.036* | |
H6B | 0.6012 | 0.0807 | −0.0666 | 0.036* | |
O1 | 0.3833 (3) | −0.0182 (6) | 0.22220 (19) | 0.0398 (11) | 0.50 |
H1AW | 0.3638 | −0.1157 | 0.2375 | 0.048* | 0.50 |
H1BW | 0.3286 | 0.0123 | 0.2006 | 0.048* | 0.50 |
O2 | 0.6553 (3) | 0.1986 (6) | 0.29770 (16) | 0.0276 (10) | 0.50 |
H2AW | 0.7164 | 0.1892 | 0.2864 | 0.033* | 0.50 |
H2BW | 0.6535 | 0.1404 | 0.3252 | 0.033* | 0.50 |
O3 | 0.3257 (3) | 0.3417 (6) | 0.22504 (19) | 0.0392 (12) | 0.50 |
H3AW | 0.3247 | 0.4461 | 0.2395 | 0.047* | 0.50 |
H3BW | 0.2620 | 0.2978 | 0.2262 | 0.047* | 0.50 |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ca1 | 0.0218 (5) | 0.0597 (7) | 0.0204 (5) | 0.000 | 0.0022 (3) | 0.000 |
N1 | 0.0210 (12) | 0.0223 (14) | 0.0265 (14) | 0.0006 (10) | 0.0037 (10) | −0.0018 (11) |
C2 | 0.0208 (14) | 0.0181 (16) | 0.0244 (17) | −0.0019 (11) | 0.0034 (11) | 0.0021 (13) |
N21 | 0.0234 (12) | 0.0216 (14) | 0.0255 (14) | 0.0006 (10) | 0.0023 (10) | 0.0024 (11) |
O21 | 0.0330 (12) | 0.0258 (13) | 0.0532 (15) | 0.0019 (10) | 0.0148 (10) | −0.0049 (11) |
C21 | 0.0299 (16) | 0.0206 (17) | 0.0241 (16) | −0.0027 (12) | 0.0054 (12) | −0.0004 (13) |
N22 | 0.0269 (13) | 0.0185 (15) | 0.0304 (15) | −0.0013 (10) | 0.0068 (10) | 0.0004 (11) |
C22 | 0.0254 (15) | 0.0223 (18) | 0.0223 (16) | 0.0034 (12) | 0.0006 (12) | 0.0034 (13) |
C23 | 0.0228 (15) | 0.0246 (18) | 0.0359 (18) | −0.0032 (12) | 0.0002 (12) | 0.0023 (14) |
C24 | 0.0247 (16) | 0.0283 (18) | 0.0196 (16) | −0.0002 (13) | 0.0063 (12) | −0.0026 (13) |
O22 | 0.0295 (12) | 0.0566 (17) | 0.0406 (14) | −0.0149 (11) | −0.0089 (10) | 0.0194 (12) |
O23 | 0.0316 (11) | 0.0249 (12) | 0.0246 (12) | −0.0058 (9) | 0.0028 (8) | 0.0007 (9) |
N3 | 0.0190 (12) | 0.0206 (14) | 0.0221 (13) | 0.0017 (9) | 0.0009 (9) | 0.0010 (10) |
C3 | 0.0283 (16) | 0.0289 (18) | 0.0258 (17) | 0.0086 (13) | −0.0038 (12) | −0.0006 (14) |
C4 | 0.0219 (15) | 0.0191 (16) | 0.0266 (17) | −0.0019 (12) | 0.0034 (12) | 0.0009 (13) |
O4 | 0.0257 (11) | 0.0316 (13) | 0.0275 (12) | 0.0082 (9) | 0.0049 (8) | −0.0006 (10) |
C5 | 0.0211 (14) | 0.0174 (16) | 0.0244 (17) | −0.0006 (11) | 0.0023 (11) | −0.0021 (13) |
N5 | 0.0286 (13) | 0.0243 (15) | 0.0284 (15) | 0.0000 (10) | −0.0006 (11) | 0.0021 (12) |
O5 | 0.0367 (12) | 0.0357 (14) | 0.0296 (13) | 0.0035 (10) | −0.0092 (9) | −0.0003 (10) |
C6 | 0.0216 (14) | 0.0173 (16) | 0.0275 (17) | −0.0014 (11) | 0.0015 (11) | 0.0015 (13) |
N6 | 0.0251 (13) | 0.0320 (16) | 0.0317 (15) | 0.0088 (11) | −0.0016 (11) | −0.0011 (12) |
O1 | 0.042 (3) | 0.036 (3) | 0.039 (3) | −0.006 (2) | −0.003 (2) | 0.000 (2) |
O2 | 0.019 (2) | 0.038 (3) | 0.026 (2) | 0.0005 (18) | 0.0038 (16) | 0.013 (2) |
O3 | 0.030 (2) | 0.037 (3) | 0.049 (3) | −0.005 (2) | −0.002 (2) | 0.000 (3) |
Geometric parameters (Å, º) top
Ca1—O1 | 2.676 (4) | C22—O21 | 1.232 (3) |
Ca1—O2 | 2.278 (4) | C22—N22 | 1.327 (4) |
Ca1—O3 | 2.334 (4) | N22—C23 | 1.447 (4) |
Ca1—O21 | 2.388 (2) | C23—C24 | 1.526 (4) |
Ca1—O23i | 2.437 (2) | C24—O22 | 1.250 (3) |
Ca1—O1ii | 2.676 (4) | C24—O23 | 1.260 (3) |
Ca1—O2ii | 2.278 (4) | N21—H21 | 0.88 |
Ca1—O3ii | 2.334 (4) | C21—H21A | 0.99 |
Ca1—O21ii | 2.388 (2) | C21—H21B | 0.99 |
Ca1—O23iii | 2.437 (2) | N22—H22A | 0.88 |
N1—C2 | 1.341 (3) | C23—H23A | 0.99 |
C2—N3 | 1.384 (3) | C23—H23B | 0.99 |
N3—C4 | 1.392 (4) | C3—H3A | 0.98 |
C4—C5 | 1.455 (4) | C3—H3B | 0.98 |
C5—C6 | 1.449 (4) | C3—H3C | 0.98 |
C6—N1 | 1.337 (4) | N6—H6A | 0.88 |
C2—N21 | 1.324 (4) | N6—H6B | 0.88 |
N3—C3 | 1.477 (3) | O1—H1AW | 0.90 |
C4—O4 | 1.231 (3) | O1—H1BW | 0.88 |
C5—N5 | 1.339 (4) | O2—H2AW | 0.87 |
N5—O5 | 1.288 (3) | O2—H2BW | 0.85 |
C6—N6 | 1.322 (3) | O3—H3AW | 0.89 |
N21—C21 | 1.460 (4) | O3—H3BW | 0.89 |
C21—C22 | 1.513 (4) | | |
| | | |
O21—Ca1—O21ii | 128.61 (11) | O21—C22—C21 | 118.1 (3) |
O23i—Ca1—O23iii | 77.97 (10) | N22—C22—C21 | 118.5 (3) |
O21—Ca1—O23i | 80.29 (7) | N22—C23—C24 | 113.7 (2) |
O21—Ca1—O23iii | 147.44 (7) | N22—C23—H23A | 108.8 |
O1—Ca1—O2 | 113.79 (16) | C24—C23—H23A | 108.8 |
O1—Ca1—O3 | 69.53 (15) | N22—C23—H23B | 108.8 |
O2—Ca1—O3 | 163.04 (16) | C24—C23—H23B | 108.8 |
O21—Ca1—O1 | 72.63 (12) | H23A—C23—H23B | 107.7 |
O21—Ca1—O2 | 85.89 (12) | O22—C24—O23 | 125.7 (3) |
O21—Ca1—O3 | 110.60 (13) | O22—C24—C23 | 118.8 (3) |
O23i—Ca1—O1 | 119.34 (11) | O23—C24—C23 | 115.5 (2) |
O23i—Ca1—O2 | 117.14 (12) | C24—O23—Ca1iv | 127.65 (17) |
O23i—Ca1—O3 | 71.28 (13) | C2—N3—C4 | 121.2 (2) |
O2ii—Ca1—O21 | 83.50 (11) | C2—N3—C3 | 120.8 (2) |
O3ii—Ca1—O21 | 82.93 (13) | C4—N3—C3 | 117.9 (2) |
O2—Ca1—O21ii | 83.50 (11) | N3—C3—H3A | 109.5 |
O3—Ca1—O21ii | 82.93 (13) | N3—C3—H3B | 109.5 |
O2ii—Ca1—O23i | 82.83 (12) | H3A—C3—H3B | 109.5 |
O3ii—Ca1—O23i | 84.87 (13) | N3—C3—H3C | 109.5 |
O21ii—Ca1—O23i | 147.44 (7) | H3A—C3—H3C | 109.5 |
O2—Ca1—O23iii | 82.83 (12) | H3B—C3—H3C | 109.5 |
O3—Ca1—O23iii | 84.87 (13) | O4—C4—N3 | 120.5 (2) |
O21ii—Ca1—O1 | 66.43 (12) | O4—C4—C5 | 123.2 (3) |
O23iii—Ca1—O1 | 139.65 (11) | N3—C4—C5 | 116.3 (2) |
O21—Ca1—O1ii | 66.43 (12) | N5—C5—C6 | 127.3 (2) |
O23i—Ca1—O1ii | 139.65 (11) | N5—C5—C4 | 115.0 (2) |
C6—N1—C2 | 118.3 (2) | C6—C5—C4 | 117.7 (2) |
N21—C2—N1 | 118.1 (2) | O5—N5—C5 | 117.9 (2) |
N21—C2—N3 | 118.1 (2) | N6—C6—N1 | 118.3 (3) |
N1—C2—N3 | 123.8 (3) | N6—C6—C5 | 119.0 (3) |
C2—N21—C21 | 122.4 (2) | N1—C6—C5 | 122.7 (2) |
C2—N21—H21 | 118.8 | C6—N6—H6A | 120.0 |
C21—N21—H21 | 118.8 | C6—N6—H6B | 120.0 |
C22—O21—Ca1 | 158.5 (2) | H6A—N6—H6B | 120.0 |
N21—C21—C22 | 116.4 (2) | Ca1—O1—H1AW | 136 |
N21—C21—H21A | 108.2 | Ca1—O1—H1BW | 110 |
C22—C21—H21A | 108.2 | H1AW—O1—H1BW | 106 |
N21—C21—H21B | 108.2 | Ca1—O2—H2AW | 126 |
C22—C21—H21B | 108.2 | Ca1—O2—H2BW | 118 |
H21A—C21—H21B | 107.3 | H2AW—O2—H2BW | 111 |
C22—N22—C23 | 124.0 (2) | Ca1—O3—H3AW | 100 |
C22—N22—H22A | 118.0 | Ca1—O3—H3BW | 138 |
C23—N22—H22A | 118.0 | H3AW—O3—H3BW | 106 |
O21—C22—N22 | 123.3 (3) | | |
| | | |
C6—N1—C2—N21 | −178.5 (2) | O22—C24—O23—Ca1iv | 4.9 (4) |
C6—N1—C2—N3 | 0.6 (4) | C23—C24—O23—Ca1iv | −173.51 (18) |
N1—C2—N21—C21 | −3.8 (4) | N21—C2—N3—C4 | −179.4 (2) |
O2ii—Ca1—O21—C22 | −150.5 (6) | N1—C2—N3—C4 | 1.5 (4) |
O2—Ca1—O21—C22 | 7.2 (6) | N21—C2—N3—C3 | 0.8 (4) |
O3ii—Ca1—O21—C22 | 39.7 (6) | N1—C2—N3—C3 | −178.3 (3) |
O3—Ca1—O21—C22 | −168.7 (5) | C2—N3—C4—O4 | 177.7 (3) |
O21ii—Ca1—O21—C22 | −71.1 (5) | C3—N3—C4—O4 | −2.5 (4) |
O23i—Ca1—O21—C22 | 125.7 (5) | C2—N3—C4—C5 | −3.1 (4) |
O23iii—Ca1—O21—C22 | 77.0 (6) | C3—N3—C4—C5 | 176.7 (2) |
O1—Ca1—O21—C22 | −109.3 (6) | O4—C4—C5—N5 | 3.4 (4) |
O1ii—Ca1—O21—C22 | −31.0 (5) | N3—C4—C5—N5 | −175.8 (2) |
Ca1—O21—C22—N22 | 102.7 (5) | O4—C4—C5—C6 | −178.1 (3) |
Ca1—O21—C22—C21 | −76.9 (6) | N3—C4—C5—C6 | 2.7 (4) |
C23—N22—C22—O21 | −2.1 (4) | C6—C5—N5—O5 | 3.2 (4) |
N21—C21—C22—O21 | 179.1 (2) | C4—C5—N5—O5 | −178.5 (2) |
N3—C2—N21—C21 | 177.1 (2) | C2—N1—C6—N6 | 178.3 (2) |
C2—N21—C21—C22 | 80.8 (3) | C2—N1—C6—C5 | −0.9 (4) |
N21—C21—C22—N22 | −0.5 (4) | N5—C5—C6—N6 | −1.7 (4) |
C21—C22—N22—C23 | 177.5 (3) | C4—C5—C6—N6 | 180.0 (3) |
C22—N22—C23—C24 | −111.7 (3) | N5—C5—C6—N1 | 177.5 (3) |
N22—C23—C24—O22 | 21.3 (4) | C4—C5—C6—N1 | −0.8 (4) |
N22—C23—C24—O23 | −160.1 (2) | | |
Symmetry codes: (i) x, y+1, z; (ii) −x+1, y, −z+1/2; (iii) −x+1, y+1, −z+1/2; (iv) x, y−1, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1AW···O22ii | 0.90 | 2.16 | 3.048 (5) | 168 |
O1—H1BW···O5v | 0.88 | 2.32 | 2.962 (5) | 130 |
O2—H2AW···O22vi | 0.87 | 1.82 | 2.667 (4) | 166 |
O2—H2BW···O5vii | 0.85 | 1.82 | 2.655 (5) | 164 |
O3—H3AW···O22iii | 0.89 | 1.82 | 2.692 (5) | 166 |
O3—H3BW···O22viii | 0.89 | 1.89 | 2.744 (5) | 162 |
N6—H6B···O5 | 0.88 | 1.94 | 2.598 (3) | 131 |
N6—H6A···O4viii | 0.88 | 1.97 | 2.761 (3) | 149 |
N21—H21···O23ix | 0.88 | 2.05 | 2.861 (3) | 152 |
N22—H22A···N5x | 0.88 | 2.34 | 3.132 (3) | 150 |
Symmetry codes: (ii) −x+1, y, −z+1/2; (iii) −x+1, y+1, −z+1/2; (v) −x+1, −y, −z; (vi) −x+3/2, y+1/2, −z+1/2; (vii) x, −y, z+1/2; (viii) x−1/2, y+1/2, z; (ix) x+1/2, y+1/2, z; (x) −x+3/2, −y−1/2, −z. |
Experimental details
Crystal data |
Chemical formula | [Ca(C9H11N6O5)2(H2O)3] |
Mr | 660.60 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 150 |
a, b, c (Å) | 12.7815 (7), 7.7010 (7), 26.271 (2) |
β (°) | 96.418 (5) |
V (Å3) | 2569.7 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.34 |
Crystal size (mm) | 0.15 × 0.08 × 0.01 |
|
Data collection |
Diffractometer | KappaCCD diffractometer |
Absorption correction | Multi-scan )SORTAV; Blessing, 1995, 1997) |
Tmin, Tmax | 0.951, 0.997 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 17345, 2553, 1641 |
Rint | 0.090 |
(sin θ/λ)max (Å−1) | 0.623 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.135, 1.00 |
No. of reflections | 2553 |
No. of parameters | 214 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.32, −0.36 |
Selected geometric parameters (Å, º) topCa1—O1 | 2.676 (4) | C4—O4 | 1.231 (3) |
Ca1—O2 | 2.278 (4) | C5—N5 | 1.339 (4) |
Ca1—O3 | 2.334 (4) | N5—O5 | 1.288 (3) |
Ca1—O21 | 2.388 (2) | C6—N6 | 1.322 (3) |
Ca1—O23i | 2.437 (2) | N21—C21 | 1.460 (4) |
N1—C2 | 1.341 (3) | C21—C22 | 1.513 (4) |
C2—N3 | 1.384 (3) | C22—O21 | 1.232 (3) |
N3—C4 | 1.392 (4) | C22—N22 | 1.327 (4) |
C4—C5 | 1.455 (4) | N22—C23 | 1.447 (4) |
C5—C6 | 1.449 (4) | C23—C24 | 1.526 (4) |
C6—N1 | 1.337 (4) | C24—O22 | 1.250 (3) |
C2—N21 | 1.324 (4) | C24—O23 | 1.260 (3) |
N3—C3 | 1.477 (3) | | |
| | | |
O21—Ca1—O21ii | 128.61 (11) | O21—Ca1—O1 | 72.63 (12) |
O23i—Ca1—O23iii | 77.97 (10) | O21—Ca1—O2 | 85.89 (12) |
O21—Ca1—O23i | 80.29 (7) | O21—Ca1—O3 | 110.60 (13) |
O21—Ca1—O23iii | 147.44 (7) | O23i—Ca1—O1 | 119.34 (11) |
O1—Ca1—O2 | 113.79 (16) | O23i—Ca1—O2 | 117.14 (12) |
O1—Ca1—O3 | 69.53 (15) | O23i—Ca1—O3 | 71.28 (13) |
O2—Ca1—O3 | 163.04 (16) | | |
| | | |
N3—C2—N21—C21 | 177.1 (2) | C22—N22—C23—C24 | −111.7 (3) |
C2—N21—C21—C22 | 80.8 (3) | N22—C23—C24—O22 | 21.3 (4) |
N21—C21—C22—N22 | −0.5 (4) | N22—C23—C24—O23 | −160.1 (2) |
C21—C22—N22—C23 | 177.5 (3) | | |
Symmetry codes: (i) x, y+1, z; (ii) −x+1, y, −z+1/2; (iii) −x+1, y+1, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1AW···O22ii | 0.90 | 2.16 | 3.048 (5) | 168 |
O1—H1BW···O5iv | 0.88 | 2.32 | 2.962 (5) | 130 |
O2—H2AW···O22v | 0.87 | 1.82 | 2.667 (4) | 166 |
O2—H2BW···O5vi | 0.85 | 1.82 | 2.655 (5) | 164 |
O3—H3AW···O22iii | 0.89 | 1.82 | 2.692 (5) | 166 |
O3—H3BW···O22vii | 0.89 | 1.89 | 2.744 (5) | 162 |
N6—H6B···O5 | 0.88 | 1.94 | 2.598 (3) | 131 |
N6—H6A···O4vii | 0.88 | 1.97 | 2.761 (3) | 149 |
N21—H21···O23viii | 0.88 | 2.05 | 2.861 (3) | 152 |
N22—H22A···N5ix | 0.88 | 2.34 | 3.132 (3) | 150 |
Symmetry codes: (ii) −x+1, y, −z+1/2; (iii) −x+1, y+1, −z+1/2; (iv) −x+1, −y, −z; (v) −x+3/2, y+1/2, −z+1/2; (vi) x, −y, z+1/2; (vii) x−1/2, y+1/2, z; (viii) x+1/2, y+1/2, z; (ix) −x+3/2, −y−1/2, −z. |
The potassium salt of the pyrimidylglycylglycine [(I), LH] crystallizes as a monohydrate, K+L-·H2O, in which the cations and anions form a three-dimensional coordination polymer network, where the water molecules play no significant structural role (Low, Arranz et al., 2001). By contrast, in the calcium salt, which crystallizes as the trihydrate Ca2+(L-)2·3H2O, (II), the cations and anions form a one-dimensional coordination polymer; the individual strands of this polymer are connected into a single three-dimensional framework by means of a series of hydrogen bonds, dominated by those formed by the water molecules.
Compound (II) crystallizes in space group C2/c with Z' = 0.5; the Ca atom lies on a twofold rotation axis, selected for convenience to be that along (1/2, y, 1/4) with the anion in a general position. There are three water molecules coordinated to the calcium, each disordered over two sites with equal occupancy (Fig. 1). The water molecules can only adopt one of the two possible arrangements about the Ca2+ through geometry considerations, in order to avoid unacceptably short O···O distances between water molecules bound to the same Ca [O1···O2i 1.802 (7) Å and O3···O2i 1.289 (6) Å; symmetry code: (i) 1 - x, y, 0.5 - z].
The Ca atom is also coordinated by four O atoms, two carboxylic acid and two amidic, each from a different anionic ligand (Table 1 and Fig. 2), and the resulting CaO4 unit can be described as a slight distortion of square planar towards tetrahedral. Overall, the coordination geometry at calcium, including the three water molecules, is distorted pentagonal bipyramidal (Fig. 3). The Ca—O distances involving water span those involving the anionic ligands (Table 1); the carboxylate distance Ca—O23 is, unexpectedly, longer than the amidic distance Ca—O21. This coordination behaviour of the anion L- towards calcium may be contrasted with its behaviour towards potassium where, in addition to all three of the O atoms in the glycylglycinate side chain, the nitrosyl O5 atom also acts as one of the ligating atoms (Low, Arranz et al., 2001). The mean value of the Ca—O distances is 2.420 (4) Å; if the outlier value for the rather weakly bound O1 is omitted, the mean value of the other six Ca—O distances is 2.377 (4) Å; the mean value of the K—O distances in the analogous K+L-·H2O is 2.731 (2) Å (Low, Arranz et al., 2001). The difference between the mean Ca—O and K—O distances, ca 0.31 Å if Ca is regarded as seven-coordinate or ca 0.35 Å if it is regarded as six-coordinate, precisely reflect the differences between the corresponding ionic radii, as tabulated by Shannon & Prewitt (1970): K+ (six-coordinate) 1.38, Ca2+ (seven-coordinate) 1.07 and Ca2+ (six-coordinate) 1.00 Å.
The supramolecular structure can be most readily analysed and described using the substructure approach (Gregson et al., 2000). Each anion acts as a bridging ligand between adjacent Ca centres on a given twofold axis, thus generating a chain of 14-membered rings, fused in spiro fashion at the Ca atom (Fig. 2). Four of these chains run through each unit cell, along the lines (1/2, y, 1/4), (1/2, y, 3/4), (1, y, 1/4) and (1, y, 3/4), and each chain is linked to four neighbouring chains by means of O—H···O hydrogen bonds in which the coordinated water molecules act as the donors (Table 2). It is necessary to emphasize at this point, in respect of the disorder of the water sites, that although the site occupancies are fully correlated at each individual Ca centre, as described earlier, there are no such constraints on the water-site occupancies at neighbouring Ca sites along a chain, or on those at Ca sites in different chains.
The water O1 atom at (x, y, z) acts as hydrogen-bond donor, via H1AW, forming a rather long weak hydrogen bond, to O22 at (1 - x, y, 0.5 - z), which is part of the same [010] chain; similarly O3 at (x, y, z) acts as donor, via H3AW, to O22 at (1 - x, 1 + y, 0.5 - z), also part of the same chain. The other four O—H···O hydrogen bonds all serve to link adjacent chains. The water O2 atom at (x, y, z) is a component of the chain along (1/2, y, 1/4); O2 acts as hydrogen-bond donor, via H2AW, to O22 at (1.5 - x, 0.5 + y, 0.5 - z), which is a component of the chain along (1, y, 1/4), and it also acts as hydrogen-bond donor, via H2BW, to O5 at (x, -y, 0.5 + z), which is a component of the chain along (1/2, y, 3/4). Propagation by the space group of the these two interchain O—H···O hydrogen bonds, both formed by the water O2 atom, would of itself be sufficient to link all of the chains into a single framework. There are, however, several more hydrogen bonds which further reinforce the links between the chains. The water O3 atom at (x, y, z) acts as donor, via H3BW, to O22 at (-0.5 + x, 0.5 + y, z), which is a component of the chain along (0, y, 1/4), and the water O1 atom at (x, y, z) acts as donor, via H1BW and in a rather weak hydrogen bond, to O5 at (1 - x, -y, -z), a component of the chain along (1/2, y, -0.25). Thus, by means of these four O—H···O hydrogen bonds, the reference chain along (1/2, y, 1/4) is directly linked to those along (1/2, y, -0.25) and (1/2, y, 3/4) and to those along (1, y, 1/4) and (0, y, 1/4). Three hydrogen bonds with N—H donors provide further links (Table 2); N21 at (x, y, z) in the chain along (1/2, y, 1/4) acts as donor to O23 at (0.5 + x, 0.5 + y, z) in the chain along (1, y, 1/4), while N6 at (x, y, z) acts as donor, via H6A, to O4 at (-0.5 + x, 0.5 + y, z) in the chain along (0, y, 1/4), and finally, N22 at (x, y, z) forms a rather weaker hydrogen bond to N5 at (1.5 - x, -0.5 - y, -z), a component of the chain along (1, y, -0.25). Each Ca(H2O)3 unit along each chain gives rise to a similar set of hydrogen bonds, hence tying all the metal–anion chains into a single bundle.
The bond distances (Table 1) within the heterocyclic ring show evidence of a marked polarization of the electronic structure of this ring, as noted in previous studies (Low et al., 2000; Low, Moreno Sánchez et al., 2001; Low, Arranz et al., 2001). In particular, the C2—N1 bond is the longest of the C—N bonds in the sequence N2—C2—N1—C6—N6, although it is the only such bond which is represented as a double bond in the conventional representation (IIIa); bonds C4—C5 and C5—C6, respectively single and double bonds in form (IIIa), do not differ significantly in length, and the difference between the C5—N5 and N5—O5 nitroso distances is far smaller than expected from (IIIa) (Low et al., 2000). All of these observations point to the importance of the polarized form (IIIb), confirmed by the behaviour of O5 as a hydrogen-bond acceptor.
In the glycylglycinate side chain, the two C—O distances in the carboxylate group are very similar, and the amidic C—O distance is identical, within experimental uncertainty, to the amidic distance C4—O4. The conformation of the side chain (Table 1), which shows some unexpected torsion angles, is probably largely determined by combination of the requirements of O21 and O23 in coordinating to different Ca sites, and the extensive hydrogen bonding involving both donor and acceptor sites in the side chain.