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The title compound is a hydrated salt, 1,4-diazoniabicyclo[2.2.2]octane-
N-[(hydroxyphosphinato)methyl]iminiodiacetate-water (1/1/1.5), C
6H
14N
22+·C
5H
8NO
7P
2-·1.5H
2O, in which one of the water molecules lies across a twofold rotation axis in space group
P2/
n. The ionic components are linked into sheets by a combination of a three-centre N-H
(O)
2 hydrogen bond and two-centre O-H
O and N-H
O hydrogen bonds, and these sheets are pairwise linked by the water molecules into bilayers, by means of further O-H
O hydrogen bonds.
Supporting information
CCDC reference: 193422
To prepare salt (I), equimolar quantities of the two organic components,
N-(phosphonomethyl)iminodiacetic acid and
1,4-diazabicyclo[2.2.2]octane, were separately dissolved in methanol. The
solutions were mixed and the mixture was set aside to crystallize, exposed to
the laboratory atmosphere, providing analytically pure (I). Analysis, found: C
36.1, H 7.3, N 11.5%; C22H50N6O17P2 requires: C 36.1, H 6.9, N
11.5%. Crystals of (I) suitable for single-crystal X-ray diffraction were
selected directly from the analytical sample.
Compound (I) crystallized in the monoclinic system, space group P2/n or Pn from
the systematic absences; P2/n was established by the analysis. H atoms were
treated as riding atoms, with C—H = 0.99, N—H = 0.93 and O—H = 0.84 Å.
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, 2002); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
1,4-diazoniabicyclo[2.2.2]octane-
N-[(hydroxyphosphinato)methyl]iminiodiacetate -water (1/1/1.5
top
Crystal data top
C6H14N22+·C5H8NO7P2−·1.5H2O | F(000) = 780 |
Mr = 366.31 | Dx = 1.491 Mg m−3 |
Monoclinic, P2/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yac | Cell parameters from 3693 reflections |
a = 14.1042 (5) Å | θ = 2.9–27.5° |
b = 7.0560 (3) Å | µ = 0.22 mm−1 |
c = 16.4004 (7) Å | T = 150 K |
β = 90.1130 (18)° | Needle, colourless |
V = 1632.15 (11) Å3 | 0.16 × 0.08 × 0.06 mm |
Z = 4 | |
Data collection top
Nonius KappaCCD area-detector diffractometer | 2841 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed X-ray tube | Rint = 0.053 |
Graphite monochromator | θmax = 27.5°, θmin = 2.9° |
ϕ scans, and ω scans with κ offsets | h = −18→18 |
12611 measured reflections | k = −9→8 |
3693 independent reflections | l = −21→21 |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.038 | H-atom parameters constrained |
wR(F2) = 0.096 | w = 1/[σ2(Fo2) + (0.0211P)2 + 0.6209P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
3693 reflections | Δρmax = 0.28 e Å−3 |
216 parameters | Δρmin = −0.35 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0059 (14) |
Crystal data top
C6H14N22+·C5H8NO7P2−·1.5H2O | V = 1632.15 (11) Å3 |
Mr = 366.31 | Z = 4 |
Monoclinic, P2/n | Mo Kα radiation |
a = 14.1042 (5) Å | µ = 0.22 mm−1 |
b = 7.0560 (3) Å | T = 150 K |
c = 16.4004 (7) Å | 0.16 × 0.08 × 0.06 mm |
β = 90.1130 (18)° | |
Data collection top
Nonius KappaCCD area-detector diffractometer | 2841 reflections with I > 2σ(I) |
12611 measured reflections | Rint = 0.053 |
3693 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.28 e Å−3 |
3693 reflections | Δρmin = −0.35 e Å−3 |
216 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
P1 | 0.35479 (3) | 0.49736 (6) | 0.37217 (3) | 0.01558 (13) | |
O1 | 0.09501 (8) | 0.57915 (18) | 0.62119 (8) | 0.0259 (3) | |
O2 | 0.13606 (8) | 0.81849 (17) | 0.53953 (7) | 0.0229 (3) | |
O3 | 0.40966 (10) | 1.15406 (18) | 0.56061 (9) | 0.0331 (3) | |
O4 | 0.33110 (9) | 1.02862 (17) | 0.45382 (8) | 0.0253 (3) | |
O5 | 0.28201 (8) | 0.33296 (16) | 0.38708 (7) | 0.0203 (3) | |
O6 | 0.29982 (8) | 0.65875 (16) | 0.33464 (7) | 0.0182 (3) | |
O7 | 0.44295 (8) | 0.43094 (18) | 0.33075 (8) | 0.0238 (3) | |
N1 | 0.31306 (9) | 0.69209 (19) | 0.51503 (8) | 0.0147 (3) | |
C1 | 0.15070 (12) | 0.6613 (2) | 0.57395 (10) | 0.0180 (3) | |
C2 | 0.24396 (11) | 0.5615 (2) | 0.55575 (11) | 0.0180 (3) | |
C3 | 0.36725 (12) | 1.0257 (2) | 0.52515 (11) | 0.0207 (4) | |
C4 | 0.35272 (12) | 0.8392 (2) | 0.57152 (10) | 0.0187 (4) | |
C5 | 0.39075 (11) | 0.5840 (2) | 0.47244 (10) | 0.0168 (3) | |
N11 | 0.39288 (9) | 0.85447 (19) | 0.22781 (8) | 0.0162 (3) | |
N21 | 0.50729 (10) | 1.0260 (2) | 0.13839 (9) | 0.0171 (3) | |
C11 | 0.43010 (12) | 0.7211 (2) | 0.16478 (10) | 0.0183 (4) | |
C12 | 0.47273 (11) | 0.9288 (3) | 0.27893 (10) | 0.0193 (4) | |
C13 | 0.34342 (11) | 1.0169 (2) | 0.18775 (11) | 0.0180 (4) | |
C21 | 0.51327 (12) | 0.8186 (2) | 0.12124 (11) | 0.0199 (4) | |
C22 | 0.53196 (12) | 1.0631 (3) | 0.22592 (10) | 0.0199 (4) | |
C23 | 0.40918 (11) | 1.0974 (2) | 0.12157 (11) | 0.0190 (4) | |
O8 | 0.12465 (9) | 0.4676 (2) | 0.78408 (8) | 0.0299 (3) | |
O9 | 0.2500 | 0.1535 (3) | 0.7500 | 0.0660 (9) | |
H5 | 0.3098 | 0.2410 | 0.4092 | 0.030* | |
H1 | 0.2796 | 0.7567 | 0.4748 | 0.018* | |
H2A | 0.2718 | 0.5139 | 0.6073 | 0.022* | |
H2B | 0.2318 | 0.4511 | 0.5199 | 0.022* | |
H4A | 0.4140 | 0.7951 | 0.5940 | 0.022* | |
H4B | 0.3085 | 0.8597 | 0.6175 | 0.022* | |
H5A | 0.4098 | 0.4749 | 0.5068 | 0.020* | |
H5B | 0.4467 | 0.6675 | 0.4662 | 0.020* | |
H11 | 0.3502 | 0.7905 | 0.2611 | 0.019* | |
H21 | 0.5500 | 1.0899 | 0.1051 | 0.021* | |
H11A | 0.3796 | 0.6896 | 0.1250 | 0.022* | |
H11B | 0.4519 | 0.6023 | 0.1909 | 0.022* | |
H12A | 0.5125 | 0.8226 | 0.2987 | 0.023* | |
H12B | 0.4474 | 0.9976 | 0.3268 | 0.023* | |
H13A | 0.3288 | 1.1160 | 0.2285 | 0.022* | |
H13B | 0.2832 | 0.9734 | 0.1630 | 0.022* | |
H21A | 0.5743 | 0.7674 | 0.1415 | 0.024* | |
H21B | 0.5095 | 0.7955 | 0.0618 | 0.024* | |
H22A | 0.5178 | 1.1965 | 0.2401 | 0.024* | |
H22B | 0.6004 | 1.0402 | 0.2352 | 0.024* | |
H23A | 0.3878 | 1.0552 | 0.0670 | 0.023* | |
H23B | 0.4082 | 1.2376 | 0.1229 | 0.023* | |
H81 | 0.1248 | 0.5102 | 0.7362 | 0.063* | |
H82 | 0.0716 | 0.4966 | 0.8036 | 0.063* | |
H9 | 0.2138 | 0.2384 | 0.7679 | 0.063* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
P1 | 0.0166 (2) | 0.0133 (2) | 0.0169 (2) | 0.00007 (16) | 0.00359 (16) | 0.00105 (17) |
O1 | 0.0245 (7) | 0.0233 (7) | 0.0300 (7) | −0.0011 (5) | 0.0120 (5) | 0.0037 (6) |
O2 | 0.0218 (6) | 0.0229 (7) | 0.0241 (7) | 0.0067 (5) | 0.0071 (5) | 0.0049 (5) |
O3 | 0.0440 (8) | 0.0193 (7) | 0.0359 (8) | −0.0096 (6) | −0.0139 (6) | 0.0011 (6) |
O4 | 0.0363 (7) | 0.0168 (6) | 0.0226 (7) | −0.0038 (5) | −0.0065 (5) | 0.0030 (5) |
O5 | 0.0220 (6) | 0.0151 (6) | 0.0238 (7) | −0.0021 (5) | −0.0013 (5) | 0.0040 (5) |
O6 | 0.0204 (6) | 0.0162 (6) | 0.0178 (6) | 0.0008 (4) | 0.0016 (5) | 0.0032 (5) |
O7 | 0.0223 (6) | 0.0230 (7) | 0.0263 (7) | 0.0043 (5) | 0.0086 (5) | −0.0020 (5) |
N1 | 0.0151 (6) | 0.0135 (7) | 0.0155 (7) | 0.0003 (5) | 0.0009 (5) | 0.0008 (5) |
C1 | 0.0197 (8) | 0.0175 (8) | 0.0166 (8) | 0.0003 (6) | 0.0024 (6) | −0.0025 (7) |
C2 | 0.0167 (8) | 0.0146 (8) | 0.0227 (9) | −0.0011 (6) | 0.0055 (6) | 0.0027 (7) |
C3 | 0.0212 (9) | 0.0160 (8) | 0.0250 (9) | −0.0003 (6) | −0.0016 (7) | 0.0007 (7) |
C4 | 0.0225 (8) | 0.0164 (8) | 0.0171 (8) | −0.0015 (6) | −0.0012 (6) | −0.0008 (7) |
C5 | 0.0136 (7) | 0.0155 (8) | 0.0212 (9) | 0.0020 (6) | 0.0031 (6) | 0.0007 (7) |
N11 | 0.0168 (7) | 0.0148 (7) | 0.0170 (7) | −0.0003 (5) | 0.0022 (5) | 0.0013 (6) |
N21 | 0.0169 (7) | 0.0171 (7) | 0.0174 (7) | −0.0009 (5) | 0.0030 (5) | 0.0018 (6) |
C11 | 0.0205 (8) | 0.0155 (8) | 0.0190 (8) | −0.0001 (6) | 0.0016 (6) | −0.0024 (7) |
C12 | 0.0206 (8) | 0.0206 (9) | 0.0169 (8) | 0.0000 (7) | −0.0003 (7) | −0.0006 (7) |
C13 | 0.0155 (8) | 0.0165 (8) | 0.0221 (9) | 0.0023 (6) | 0.0031 (6) | 0.0033 (7) |
C21 | 0.0209 (8) | 0.0169 (8) | 0.0218 (9) | 0.0004 (6) | 0.0039 (7) | −0.0026 (7) |
C22 | 0.0206 (8) | 0.0206 (9) | 0.0184 (8) | −0.0025 (7) | −0.0005 (7) | −0.0029 (7) |
C23 | 0.0169 (8) | 0.0183 (9) | 0.0218 (9) | 0.0019 (6) | 0.0011 (6) | 0.0057 (7) |
O8 | 0.0249 (7) | 0.0353 (8) | 0.0296 (7) | 0.0022 (6) | −0.0004 (5) | 0.0013 (6) |
O9 | 0.0333 (12) | 0.0286 (13) | 0.136 (3) | 0.000 | 0.0113 (14) | 0.000 |
Geometric parameters (Å, º) top
N1—C2 | 1.499 (2) | C4—H4B | 0.99 |
N1—C4 | 1.499 (2) | C5—H5A | 0.99 |
N1—C5 | 1.508 (2) | C5—H5B | 0.99 |
N11—C11 | 1.494 (2) | N11—H11 | 0.93 |
N11—C12 | 1.497 (2) | N21—H21 | 0.93 |
N11—C13 | 1.493 (2) | C11—C21 | 1.537 (2) |
N21—C21 | 1.493 (2) | C11—H11A | 0.99 |
N21—C22 | 1.499 (2) | C11—H11B | 0.99 |
N21—C23 | 1.498 (2) | C12—C22 | 1.534 (2) |
P1—O5 | 1.5685 (12) | C12—H12A | 0.99 |
P1—O6 | 1.5083 (12) | C12—H12B | 0.99 |
P1—O7 | 1.4934 (12) | C13—C23 | 1.538 (2) |
P1—C5 | 1.8253 (17) | C13—H13A | 0.99 |
C1—O1 | 1.247 (2) | C13—H13B | 0.99 |
C1—O2 | 1.262 (2) | C21—H21A | 0.99 |
C3—O3 | 1.231 (2) | C21—H21B | 0.99 |
C3—O4 | 1.275 (2) | C22—H22A | 0.99 |
O5—H5 | 0.84 | C22—H22B | 0.99 |
N1—H1 | 0.93 | C23—H23A | 0.99 |
C1—C2 | 1.522 (2) | C23—H23B | 0.99 |
C2—H2A | 0.99 | O8—H81 | 0.84 |
C2—H2B | 0.99 | O8—H82 | 0.84 |
C3—C4 | 1.533 (2) | O9—H9 | 0.84 |
C4—H4A | 0.99 | | |
| | | |
O7—P1—O6 | 118.63 (7) | C21—N21—C23 | 110.33 (13) |
O7—P1—O5 | 112.61 (7) | C21—N21—C22 | 109.77 (13) |
O6—P1—O5 | 106.61 (7) | C23—N21—C22 | 109.29 (13) |
O7—P1—C5 | 106.55 (7) | C21—N21—H21 | 109.1 |
O6—P1—C5 | 104.87 (7) | C23—N21—H21 | 109.1 |
O5—P1—C5 | 106.73 (7) | C22—N21—H21 | 109.1 |
P1—O5—H5 | 109.5 | N11—C11—C21 | 108.01 (13) |
C4—N1—C2 | 113.11 (13) | N11—C11—H11A | 110.1 |
C4—N1—C5 | 111.47 (12) | C21—C11—H11A | 110.1 |
C2—N1—C5 | 111.65 (12) | N11—C11—H11B | 110.1 |
C4—N1—H1 | 106.7 | C21—C11—H11B | 110.1 |
C2—N1—H1 | 106.7 | H11A—C11—H11B | 108.4 |
C5—N1—H1 | 106.7 | N11—C12—C22 | 107.98 (13) |
O1—C1—O2 | 125.72 (15) | N11—C12—H12A | 110.1 |
O1—C1—C2 | 116.90 (15) | C22—C12—H12A | 110.1 |
O2—C1—C2 | 117.38 (14) | N11—C12—H12B | 110.1 |
N1—C2—C1 | 111.44 (13) | C22—C12—H12B | 110.1 |
N1—C2—H2A | 109.3 | H12A—C12—H12B | 108.4 |
C1—C2—H2A | 109.3 | N11—C13—C23 | 108.18 (13) |
N1—C2—H2B | 109.3 | N11—C13—H13A | 110.1 |
C1—C2—H2B | 109.3 | C23—C13—H13A | 110.1 |
H2A—C2—H2B | 108.0 | N11—C13—H13B | 110.1 |
O3—C3—O4 | 127.89 (17) | C23—C13—H13B | 110.1 |
O3—C3—C4 | 117.54 (16) | H13A—C13—H13B | 108.4 |
O4—C3—C4 | 114.54 (15) | N21—C21—C11 | 107.92 (13) |
N1—C4—C3 | 109.74 (14) | N21—C21—H21A | 110.1 |
N1—C4—H4A | 109.7 | C11—C21—H21A | 110.1 |
C3—C4—H4A | 109.7 | N21—C21—H21B | 110.1 |
N1—C4—H4B | 109.7 | C11—C21—H21B | 110.1 |
C3—C4—H4B | 109.7 | H21A—C21—H21B | 108.4 |
H4A—C4—H4B | 108.2 | N21—C22—C12 | 108.00 (13) |
N1—C5—P1 | 112.69 (11) | N21—C22—H22A | 110.1 |
N1—C5—H5A | 109.1 | C12—C22—H22A | 110.1 |
P1—C5—H5A | 109.1 | N21—C22—H22B | 110.1 |
N1—C5—H5B | 109.1 | C12—C22—H22B | 110.1 |
P1—C5—H5B | 109.1 | H22A—C22—H22B | 108.4 |
H5A—C5—H5B | 107.8 | N21—C23—C13 | 107.71 (13) |
C13—N11—C11 | 110.09 (13) | N21—C23—H23A | 110.2 |
C13—N11—C12 | 109.14 (13) | C13—C23—H23A | 110.2 |
C11—N11—C12 | 110.06 (12) | N21—C23—H23B | 110.2 |
C13—N11—H11 | 109.2 | C13—C23—H23B | 110.2 |
C11—N11—H11 | 109.2 | H23A—C23—H23B | 108.5 |
C12—N11—H11 | 109.2 | H81—O8—H82 | 106 |
| | | |
C4—N1—C2—C1 | 72.1 (2) | C12—N11—C11—C21 | −49.8 (2) |
C5—N1—C2—C1 | −161.2 (2) | C13—N11—C12—C22 | −50.6 (2) |
O1—C1—C2—N1 | −166.7 (2) | C11—N11—C12—C22 | 70.3 (2) |
O2—C1—C2—N1 | 14.0 (2) | C11—N11—C13—C23 | −49.8 (2) |
C2—N1—C4—C3 | −144.34 (13) | C12—N11—C13—C23 | 71.1 (2) |
C5—N1—C4—C3 | 88.88 (16) | C23—N21—C21—C11 | −49.7 (2) |
O3—C3—C4—N1 | −171.7 (2) | C22—N21—C21—C11 | 70.8 (2) |
O4—C3—C4—N1 | 9.7 (2) | N11—C11—C21—N21 | −17.5 (2) |
C4—N1—C5—P1 | −150.9 (2) | C21—N21—C22—C12 | −50.3 (2) |
C2—N1—C5—P1 | 81.52 (14) | C23—N21—C22—C12 | 70.9 (2) |
O7—P1—C5—N1 | 168.3 (2) | N11—C12—C22—N21 | −16.9 (2) |
O6—P1—C5—N1 | 41.73 (13) | C21—N21—C23—C13 | 70.4 (2) |
O5—P1—C5—N1 | −71.14 (12) | C22—N21—C23—C13 | −50.4 (2) |
C13—N11—C11—C21 | 70.5 (2) | N11—C13—C23—N21 | −17.2 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O2 | 0.93 | 2.33 | 2.682 (2) | 102 |
N1—H1···O4 | 0.93 | 2.08 | 2.591 (2) | 113 |
N1—H1···O6 | 0.93 | 2.42 | 2.973 (2) | 118 |
O5—H5···O4i | 0.84 | 1.69 | 2.507 (2) | 162 |
N11—H11···O6 | 0.93 | 1.68 | 2.590 (2) | 165 |
N21—H21···O1ii | 0.93 | 2.43 | 3.062 (2) | 125 |
N21—H21···O2ii | 0.93 | 1.75 | 2.673 (2) | 173 |
O8—H81···O1 | 0.84 | 1.99 | 2.815 (2) | 166 |
O8—H82···O7iii | 0.84 | 1.94 | 2.770 (2) | 171 |
O9—H9···O8 | 0.84 | 2.07 | 2.891 (2) | 167 |
Symmetry codes: (i) x, y−1, z; (ii) x+1/2, −y+2, z−1/2; (iii) x−1/2, −y+1, z+1/2. |
Experimental details
Crystal data |
Chemical formula | C6H14N22+·C5H8NO7P2−·1.5H2O |
Mr | 366.31 |
Crystal system, space group | Monoclinic, P2/n |
Temperature (K) | 150 |
a, b, c (Å) | 14.1042 (5), 7.0560 (3), 16.4004 (7) |
β (°) | 90.1130 (18) |
V (Å3) | 1632.15 (11) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.22 |
Crystal size (mm) | 0.16 × 0.08 × 0.06 |
|
Data collection |
Diffractometer | Nonius KappaCCD area-detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12611, 3693, 2841 |
Rint | 0.053 |
(sin θ/λ)max (Å−1) | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.096, 1.03 |
No. of reflections | 3693 |
No. of parameters | 216 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.28, −0.35 |
Selected geometric parameters (Å, º) topN1—C2 | 1.499 (2) | P1—O5 | 1.5685 (12) |
N1—C4 | 1.499 (2) | P1—O6 | 1.5083 (12) |
N1—C5 | 1.508 (2) | P1—O7 | 1.4934 (12) |
N11—C11 | 1.494 (2) | P1—C5 | 1.8253 (17) |
N11—C12 | 1.497 (2) | C1—O1 | 1.247 (2) |
N11—C13 | 1.493 (2) | C1—O2 | 1.262 (2) |
N21—C21 | 1.493 (2) | C3—O3 | 1.231 (2) |
N21—C22 | 1.499 (2) | C3—O4 | 1.275 (2) |
N21—C23 | 1.498 (2) | | |
| | | |
O1—C1—C2—N1 | −166.7 (2) | N11—C11—C21—N21 | −17.5 (2) |
O3—C3—C4—N1 | −171.7 (2) | N11—C12—C22—N21 | −16.9 (2) |
O7—P1—C5—N1 | 168.3 (2) | N11—C13—C23—N21 | −17.2 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O2 | 0.93 | 2.33 | 2.682 (2) | 102 |
N1—H1···O4 | 0.93 | 2.08 | 2.591 (2) | 113 |
N1—H1···O6 | 0.93 | 2.42 | 2.973 (2) | 118 |
O5—H5···O4i | 0.84 | 1.69 | 2.507 (2) | 162 |
N11—H11···O6 | 0.93 | 1.68 | 2.590 (2) | 165 |
N21—H21···O1ii | 0.93 | 2.43 | 3.062 (2) | 125 |
N21—H21···O2ii | 0.93 | 1.75 | 2.673 (2) | 173 |
O8—H81···O1 | 0.84 | 1.99 | 2.815 (2) | 166 |
O8—H82···O7iii | 0.84 | 1.94 | 2.770 (2) | 171 |
O9—H9···O8 | 0.84 | 2.07 | 2.891 (2) | 167 |
Symmetry codes: (i) x, y−1, z; (ii) x+1/2, −y+2, z−1/2; (iii) x−1/2, −y+1, z+1/2. |
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Phenylphosphonic acid, PhP(O)(OH)2, generates a wide diversity of supramolecular structures in combination with amines (Ferguson et al., 1998), and exploratory studies of the related diacids ethane-1,2-diphosphonic acid (Glidewell et al., 2000; Wheatley et al., 2001) and phosphonoacetic acid (Farrell et al., 2001) indicate that these are both potentially versatile building blocks for supramolecular chemistry. Accordingly, we have now initiated a study of the related triacid N-(phosphonomethyl)iminodiacetic acid, (HO)2P(O)CH2N(CH2COOH)2, and we report here the structure of the hydrated adduct, (I), formed with 1,4-diazabicyclo[2.2.2]octane, C6H12N2 (DABCO). \sch
When co-crystallized from methanol exposed to air, N-(phosphonomethyl)iminodiacetic acid and DABCO generate the sesquihydrate salt C6H14N22+·C5H8NO5P2-·1.5H2O, (I) (Fig. 1), in which two H atoms have been transferred to the diamine to generate the [HN(CH2CH2)3NH]2+ cation, while in the anion, the N is protonated, leaving only one H bonded to O, to form the [HOP(O)2CH2N(H)(CH2COO)2]2- anion. One water molecule, containing atom O9, lies across a twofold rotation axis, selected as that along (1/4,y,3/4), while the water molecule containing atom O8 lies in a general position.
There are three N—H···O contacts within the anion of (I), all between the positively charged N—H unit and the negatively charged atoms O2, O4 and O6. Although the N—H···O angles are all small (Table 2), these contacts may nonetheless be significant in controlling the overall conformation of the anion. In addition to these interactions, there are seven genuine hydrogen bonds, four of the two-centre O—H···O type, one of the two-centre N—H···O type and an asymmetric three-centre N—H···(O)2 system (Table 2). Together, these link the independent components into a two-dimensional structure, which is readily analysed using the sub-structure approach (Gregson et al., 2000). The anions alone form simple chains, while the anions and cations together form single sheets, and these are linked in pairs by the water molecules to form bilayers.
The phosphonic atom O5 in the anion at (x, y, z) acts as a hydrogen-bond donor to carboxylate atom O4 in the anion at (x, y - 1, z), so generating by translation a C(8) chain parallel to the [010] direction (Fig. 2). Four of these chains run through each unit cell, and chains related to one another by the action of the n glide plane are linked into sheets by the cations. In the cation at (x, y, z), atom N11 is linked by the two-centre N—H···O hydrogen bond to atom O6 in the anion at (x, y, z), while atom N21 forms a planar three-centre system with atoms O1 and O2 in the anion at (1/2 + x, 2 - y, z - 1/2), so forming a C22(13) chain along [101] generated by the n glide plane at y = 1 (Fig. 2). The combination of [010] and [101] chains produces a (101) sheet, in which the rings defined by the shorter component of the three-centre hydrogen bond are of the R66(38) type (Fig. 2).
Pairs of (101) sheets related by the twofold rotation axis are linked into bilayers by the water molecules, whose action is most readily analysed in terms of the sub-structure they form with the anions. Water atom O8 at (x, y, z) acts as a hydrogen-bond donor, via atoms H81 and H82, respectively, to carboxylate atom O1 in the anion at (x, y, z) and to phosphonate atom O7 in the anion at (x - 1/2, 1 - y, 1/2 + z). Propagation of these two hydrogen bonds produces a C22(10) chain along [101] generated by the n glide plane at y = 1/2 (Fig. 3). Water atom O9 at (1/4, y, 3/4) acts as a hydrogen-bond donor to water O8 atoms at (x, y, z) and at (1/2 - x, y, 3/2 - z), which lie in adjacent C22(10) chains. Hence, the anions and the water molecules together form a molecular ladder along [101], with the C22(10) chains playing the role of the uprights and the O9 water molecule forming the rungs. Alternatively, this sub-structure can be regarded as a chain of edge-fused R88(28) rings (Fig. 3). The overall effect of the water molecules is the linking of the cation-anion sheets (Fig. 2) into a (101) bilayer, and it is clear that these water molecules are an integral and essential component of the supramolecular structure of (I).
All of the H atoms were clearly revealed in difference maps, and their locations are consistent with the observed P—O and C—O distances in the anion and the N—C distances in the cation (Table 1). As noted earlier, the pseudo-trigonal conformation of the anion may be influenced by the intramolecular N—H···O contacts. The N—C—C—N torsion angles (Table 1) in the cation indicate a very substantial deviation form the idealized D3 h (6m2) molecular symmetry, induced, as usual, by the avoidance of perfect eclipsing in the –CH2—CH2– units.
In view of the two-dimensional supramolecular structure of (I), it is of interest to compare this with the structure of the acid component itself, (II), Cambridge Structural Database (CSD; Allen & Kennard, 1993) reference code BOWJIG (Shkol'nikova et al., 1982), which crystallizes in space group P1. The CSD entry for BOWJIG lists coordinates for only nine of the ten H atoms and notes that the coordinates for H on one of the carboxyl atoms, O4, have been omitted from the entry because of suspected error. Coordinates for this missing H atom have been estimated by assuming that this H lies on the line O4···O2iv [symmetry code: (iv) x - 1, 1 + y, z], where the O···O distance is 2.598 Å, with an assumed bonded O—H distance of 0.84 Å. Subject to these assumptions, compound (II), which has the zwitterionic constitution (HOCOCH2)2N(H)CH2P(O)2OH, forms a hydrogen-bonded supramolecular structure which is three-dimensional. The intermolecular O—H···O hydrogen bonds link the molecules into very elegant (110) sheets built from four types of ring, all centrosymmetric, of R22(8), R22(16), R42(20) and R44(24) types (Fig. 4), while a single N—H···O hydrogen bond links each such sheet to its two neighbours, so generating a single three-dimensional framework. It is notable that (II) contains an R22(8) motif generated by the phosphonic acid units, while the very common R22(8) motif so characteristic of carboxylic acids is absent.
Table 2. Hydrogen bonds and short intramolecular contacts (Å, °)