metal-organic compounds
Sodium 1-carboxycyclopropane-1-carboxylate cyclopropane-1,1-dicarboxylic acid monohydrate
aDepartment of Chemistry, University of Glasgow, Glasgow G12 8QQ, Scotland
*Correspondence e-mail: ken@chem.gla.ac.uk
In the title type B2 acid salt, Na(LH)(LH2)·H2O [LH2 = C2H4C(CO2H)2] or Na+·C5H5O4−·C5H6O4·H2O, the vertices of a distorted octahedron centred on each Na+ cation are defined by six O atoms, one from a water molecule, one from an internally hydrogen-bonded LH− anion and four from three neutral LH2 acid molecules. Chains of edge-sharing O6 octahedra are stabilized by hydrogen bonds, which interconnect the donor H2O and LH2 molecules and LH− anions. In particular, the LH2 molecule donates H atoms to LH− and H2O and forgoes the internal hydrogen bond which stabilizes the free acid and all of its characterized salts.
Comment
The cyclopropane-1,1-dicarboxylic acid molecule, (1), hereinafter LH2, where L is C2H4C(CO2)2, contains an internal O—H⋯O hydrogen bond (see scheme) and, in consequence, its monoanion LH−, (2), is a very weak acid (Meester et al., 1971). The LH− anions of the related acid salt K(LH)·0.5H2O are also stabilized by internal O—H⋯O hydrogen bonds (Dubourg et al., 1990). We now report that our attempt to prepare the analogous sodium salt Na(LH)·0.5H2O has instead produced the title compound, Na(LH)(LH2)·H2O, (I).
Crystals of (I) are built up from Na+ cations, LH− anions, molecules of the neutral acid and water. The LH− anions (Fig. 1b) contain an internal O—H⋯O hydrogen bond with an O⋯O distance of 2.429 (3) Å, which is even shorter than the corresponding bond in the free acid (2.563 Å). The internal O—H⋯O hydrogen bonds in the LH2 molecule (Meester et al., 1971) and in the LH− anions of (I) and K(LH)·0.5H2O (Dubourg et al., 1990) all have ordered H atoms conventionally bonded to one of the O atoms. This contrasts with [Co(H2O)6](LH)2, where the anions straddle crystallographic mirror planes so that the acidic H atom is either equidistant from the two O atoms or is disordered (Schwarz et al., 1998).
The LH2 molecules of (I) (Fig. 1a) have near C2v symmetry but adopt a conformation, (3), which precludes internal hydrogen bonding [O21⋯O41 = 2.834 (3) Å]. The geometries of the LH2 molecule and LH− anion (Table 1) show typical features (see, for example, Meester et al., 1971; Dubourg et al., 1990; Muir et al., 2000; Schwarz et al., 1998). First, pairs of C—O bond lengths differ by > 0.08 Å in CO2H groups and by < 0.02 (5) Å in CO2− groups. Secondly, an electronic effect of the carboxyl substituents shortens the distal C2n—C3n (n = 1 or 2) ring bonds by 0.05–0.07 Å relative to the other C—C bonds in the cyclopropane rings. Finally, each carboxyl group nearly coincides with the plane normal to C2n—C3n passing through C1n; the C51 carboxyl group is an exception, as can be seen by comparing the C41—C11—C51—O41 torsion angle with the others in Table 1.
The ) is built from kinked chains of identical NaO6 octahedra (Table 1 and Fig. 2a), which are axially elongated along the O21⋯Na1⋯O1W direction and linked via edges which pass through crystallographic inversion centres. Atom Na1 shares octahedral edges with atoms Na1i and Na1iii, themselves related directly by translation along the a axis which thus defines the direction of the chains [symmetry codes: (i) 1 − x, 1 − y, 2 − z; (iii) −x, 1 − y, 2 − z].
of (IAtom Na1 bonds to three different LH2 molecules, one water molecule and one LH− anion. In consequence, the LH2 molecule participates in four Na—O bonds (Fig. 2b), with atom O2i bonded to both atoms Na1 and Nai, and atom O41i shared between atoms Na1 and Naiii. The LH− anion is attached to only one cation, through atom O42, which is part of the ionized carboxyl group. Similarly, the water atom O1W bonds to only one Na+ cation. Each acid molecule is also the donor in two O—H⋯O hydrogen bonds (Table 2), namely a very strong bond [O⋯O = 2.478 (3) Å] to the LH− anion and a weaker one [O⋯O = 2.642 (3) Å] to a water molecule. Atom O22 accepts a hydrogen bond from atom O1W. The resulting arrangement surrounds atoms Na1 and Na1iii by a roughly planar belt containing an (LH2–LH−–H2O)2 ring in which the individual molecules and anions are joined by hydrogen bonds. Not shown in Fig. 2(b) are the O1W—H⋯O12 hydrogen bonds which link together the chains of octahedra.
The crystal architecture of (I) uses all five available O—H groups as hydrogen-bond donors, two of these bonds being very short (O⋯O < 2.50 Å). In each independent O—H⋯O bond, the two O atoms are unrelated by Compound (I) is therefore a B2 acid salt in the classification of Speakman (1972).
It is tempting to ascribe the different stoichiometries of the sodium and potassium acid salts of cyclopropane-1,1-dicarboxylic acid to the different ionic radii of K+ and Na+. However, in the case of malonic acid, L′H2, where L′ is CH2(CO2)2, a similar difference is the result of a the salts Na(L′H) and Na(L′H)(LH2) can be produced by identical procedures, but using D2O as the solvent gives partially deuterated Na(L′H)(L′H2), whereas H2O gives Na(L′H) (Kalsbeek, 1992).
Experimental
Crystals of (I) were obtained from an aqueous solution containing sodium hydroxide and cyclopropane-1,1-dicarboxylic acid in a 1:2 molar ratio. The IR spectrum contains broad bands at 2480 and 1905 cm−1 attributable to unsymmetrical O—H⋯O hydrogen bonds.
Crystal data
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Data collection
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Refinement
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H atoms were initially located in difference maps. In the final SHELXL97 (Sheldrick, 1997) and they were then treated as riding on their parent C atoms, with C—H = 0.97 Å and Uiso(H) = 1.2Ueq(C). The positional and isotropic displacement parameters of H atoms attached to O atoms were freely refined.
the positions of the methylene H atoms were determined by the HFIX instruction inData collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
10.1107/S0108270104027052/dn1070sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S0108270104027052/dn1070Isup2.hkl
Crystals of (I) were obtained from an aqueous solution containing sodium hydroxide and cyclopropane-1,1-dicarboxylic acid in a 1:2 molar ratio. The IR spectrum contains broad bands at 2480 and 1905 cm−1, attributable to unsymmetrical O—H···O hydrogen bonds.
H atoms were initially located in difference maps. In the final
the positions of the methylene H atoms were determined by the HFIX instruction in SHELXL97 (Sheldrick, 1997) and they were then treated as riding on their parent C atoms, with C—H = 0.97 Å and Uiso(H) = 1.2Ueq(C). The positional and isotropic displacement parameters of H atoms attached to O atoms were freely refined.Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell
CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1998).Fig. 1. Views of (a) the LH2 molecule and (b) the LH− anion of (I). Displacement ellipsoids are drawn at the 20% probability level and H atoms are shown as small spheres of arbitrary radii. | |
Fig. 2. (a) Part of the infinite chain of linked NaO6 octahedra. (b) The hydrogen-bonded (LH2—LH−—H2O)2 belt around atoms Na1 and Na1iii. Displacement ellipsoids are drawn at the 20% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) 1 − x, 1 − y, 2 − z; (ii) 1 − x, y, z; (iii) −x, 1 − y, 2 − z; (iv) 1 + x, y, z.] |
Na+·C5H5O4−·C5H4O4·H2O | Z = 2 |
Mr = 300.19 | F(000) = 312 |
Triclinic, P1 | Dx = 1.593 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 5.2910 (13) Å | Cell parameters from 22 reflections |
b = 10.118 (3) Å | θ = 18.8–20.7° |
c = 12.895 (5) Å | µ = 0.17 mm−1 |
α = 109.44 (3)° | T = 293 K |
β = 98.64 (2)° | Needle, white |
γ = 99.57 (2)° | 0.48 × 0.22 × 0.16 mm |
V = 626.0 (4) Å3 |
Enraf-Nonius CAD-4 diffractometer | θmax = 28.0°, θmin = 4.7° |
non–profiled ω scans | h = −6→1 |
3932 measured reflections | k = −13→13 |
2985 independent reflections | l = −17→17 |
1654 reflections with I > 2σ(I) | 3 standard reflections every 120 min |
Rint = 0.047 | intensity decay: 1% |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.051 | w = 1/[σ2(Fo2) + (0.075P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.150 | (Δ/σ)max < 0.001 |
S = 0.99 | Δρmax = 0.31 e Å−3 |
2985 reflections | Δρmin = −0.36 e Å−3 |
202 parameters |
Na+·C5H5O4−·C5H4O4·H2O | γ = 99.57 (2)° |
Mr = 300.19 | V = 626.0 (4) Å3 |
Triclinic, P1 | Z = 2 |
a = 5.2910 (13) Å | Mo Kα radiation |
b = 10.118 (3) Å | µ = 0.17 mm−1 |
c = 12.895 (5) Å | T = 293 K |
α = 109.44 (3)° | 0.48 × 0.22 × 0.16 mm |
β = 98.64 (2)° |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.047 |
3932 measured reflections | 3 standard reflections every 120 min |
2985 independent reflections | intensity decay: 1% |
1654 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.051 | 0 restraints |
wR(F2) = 0.150 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.99 | Δρmax = 0.31 e Å−3 |
2985 reflections | Δρmin = −0.36 e Å−3 |
202 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. |
x | y | z | Uiso*/Ueq | ||
Na1 | 0.1701 (2) | 0.37779 (12) | 0.97765 (9) | 0.0352 (3) | |
O11 | 0.1927 (4) | 0.5960 (2) | 0.76510 (18) | 0.0356 (5) | |
O21 | 0.4078 (4) | 0.5633 (2) | 0.91192 (15) | 0.0336 (5) | |
O31 | 0.7072 (5) | 0.2632 (2) | 0.68504 (18) | 0.0416 (6) | |
O41 | 0.8106 (4) | 0.4147 (2) | 0.86355 (15) | 0.0301 (5) | |
C11 | 0.4859 (5) | 0.4464 (3) | 0.7284 (2) | 0.0252 (6) | |
C21 | 0.3162 (7) | 0.3705 (4) | 0.6105 (2) | 0.0469 (9) | |
H21A | 0.3326 | 0.2744 | 0.5681 | 0.056* | |
H21B | 0.14 | 0.3859 | 0.5973 | 0.056* | |
C31 | 0.5363 (7) | 0.4912 (4) | 0.6301 (2) | 0.0449 (9) | |
H31A | 0.4955 | 0.5809 | 0.6293 | 0.054* | |
H31B | 0.6882 | 0.4692 | 0.6 | 0.054* | |
C41 | 0.3651 (5) | 0.5410 (3) | 0.8125 (2) | 0.0237 (6) | |
C51 | 0.6834 (5) | 0.3729 (3) | 0.7681 (2) | 0.0248 (6) | |
H11 | 0.148 (10) | 0.650 (5) | 0.813 (4) | 0.086 (16)* | |
H31 | 0.791 (11) | 0.222 (6) | 0.703 (4) | 0.11 (2)* | |
O12 | 0.6526 (4) | −0.1338 (2) | 0.78279 (19) | 0.0480 (6) | |
O22 | 0.6093 (5) | 0.0705 (3) | 0.9017 (2) | 0.0597 (8) | |
O32 | 0.0016 (4) | 0.0965 (2) | 0.68459 (17) | 0.0434 (6) | |
O42 | 0.2679 (4) | 0.1867 (2) | 0.85276 (18) | 0.0494 (6) | |
C12 | 0.3214 (5) | −0.0282 (3) | 0.7212 (2) | 0.0261 (6) | |
C22 | 0.3379 (6) | −0.0868 (4) | 0.5981 (2) | 0.0412 (8) | |
H22A | 0.2673 | −0.0401 | 0.5495 | 0.049* | |
H22B | 0.4927 | −0.1215 | 0.5811 | 0.049* | |
C32 | 0.1525 (6) | −0.1714 (3) | 0.6373 (2) | 0.0387 (8) | |
H32A | 0.1924 | −0.2586 | 0.6444 | 0.046* | |
H32B | −0.0329 | −0.1772 | 0.6129 | 0.046* | |
C42 | 0.5417 (6) | −0.0353 (3) | 0.8047 (2) | 0.0330 (6) | |
C52 | 0.1839 (5) | 0.0932 (3) | 0.7549 (2) | 0.0303 (6) | |
H22 | 0.494 (12) | 0.131 (6) | 0.905 (5) | 0.13 (2)* | |
O1W | 0.0154 (5) | 0.2282 (2) | 1.0885 (2) | 0.0379 (5) | |
H1W | −0.094 (8) | 0.159 (4) | 1.036 (3) | 0.048 (11)* | |
H2W | 0.100 (8) | 0.180 (4) | 1.120 (3) | 0.062 (12)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Na1 | 0.0363 (7) | 0.0395 (6) | 0.0280 (6) | 0.0220 (5) | 0.0043 (5) | 0.0049 (5) |
O11 | 0.0377 (12) | 0.0496 (13) | 0.0327 (11) | 0.0314 (11) | 0.0144 (9) | 0.0189 (10) |
O21 | 0.0310 (11) | 0.0478 (12) | 0.0261 (10) | 0.0229 (10) | 0.0094 (8) | 0.0109 (9) |
O31 | 0.0457 (13) | 0.0432 (12) | 0.0326 (11) | 0.0314 (11) | 0.0027 (9) | 0.0024 (9) |
O41 | 0.0262 (10) | 0.0371 (10) | 0.0272 (10) | 0.0172 (8) | 0.0049 (8) | 0.0079 (8) |
C11 | 0.0224 (13) | 0.0319 (14) | 0.0231 (13) | 0.0154 (11) | 0.0066 (10) | 0.0075 (11) |
C21 | 0.0410 (19) | 0.060 (2) | 0.0282 (15) | 0.0316 (17) | −0.0022 (13) | −0.0032 (14) |
C31 | 0.053 (2) | 0.070 (2) | 0.0358 (16) | 0.044 (2) | 0.0250 (15) | 0.0303 (16) |
C41 | 0.0183 (13) | 0.0272 (13) | 0.0280 (14) | 0.0091 (11) | 0.0066 (10) | 0.0109 (11) |
C51 | 0.0212 (13) | 0.0303 (14) | 0.0255 (13) | 0.0108 (11) | 0.0085 (10) | 0.0097 (11) |
O12 | 0.0395 (13) | 0.0502 (13) | 0.0555 (14) | 0.0281 (11) | 0.0011 (10) | 0.0165 (11) |
O22 | 0.0478 (15) | 0.0680 (17) | 0.0428 (14) | 0.0312 (13) | −0.0117 (11) | −0.0049 (12) |
O32 | 0.0443 (13) | 0.0446 (12) | 0.0435 (12) | 0.0315 (11) | 0.0059 (10) | 0.0105 (10) |
O42 | 0.0428 (13) | 0.0451 (13) | 0.0444 (13) | 0.0241 (11) | 0.0043 (10) | −0.0080 (10) |
C12 | 0.0242 (14) | 0.0278 (13) | 0.0271 (13) | 0.0128 (11) | 0.0062 (11) | 0.0074 (11) |
C22 | 0.047 (2) | 0.0526 (19) | 0.0301 (15) | 0.0300 (17) | 0.0129 (13) | 0.0122 (14) |
C32 | 0.0409 (18) | 0.0261 (14) | 0.0410 (17) | 0.0140 (13) | −0.0002 (14) | 0.0031 (12) |
C42 | 0.0238 (14) | 0.0378 (15) | 0.0360 (15) | 0.0105 (13) | 0.0059 (12) | 0.0104 (13) |
C52 | 0.0249 (15) | 0.0298 (14) | 0.0362 (15) | 0.0106 (12) | 0.0115 (12) | 0.0082 (12) |
O1W | 0.0357 (13) | 0.0374 (12) | 0.0376 (12) | 0.0202 (11) | 0.0037 (10) | 0.0063 (10) |
Na1—O42 | 2.261 (2) | C21—C31 | 1.464 (5) |
Na1—O21i | 2.325 (2) | C21—H21A | 0.97 |
Na1—O41i | 2.370 (2) | C21—H21B | 0.97 |
Na1—O41ii | 2.384 (2) | C31—H31A | 0.97 |
Na1—O1W | 2.526 (3) | C31—H31B | 0.97 |
Na1—O21 | 2.533 (2) | O12—C42 | 1.215 (3) |
Na1—Na1iii | 3.245 (2) | O22—C42 | 1.298 (4) |
Na1—Na1i | 3.769 (3) | O22—H22 | 0.93 (6) |
O11—C41 | 1.320 (3) | O32—C52 | 1.233 (3) |
O11—H11 | 0.77 (5) | O42—C52 | 1.258 (3) |
O21—C41 | 1.204 (3) | C12—C42 | 1.491 (4) |
O21—Na1i | 2.325 (2) | C12—C52 | 1.504 (4) |
O31—C51 | 1.301 (3) | C12—C32 | 1.518 (4) |
O31—H31 | 0.72 (6) | C12—C22 | 1.520 (4) |
O41—C51 | 1.207 (3) | C22—C32 | 1.451 (5) |
O41—Na1i | 2.370 (2) | C22—H22A | 0.97 |
O41—Na1iv | 2.384 (2) | C22—H22B | 0.97 |
C11—C41 | 1.491 (3) | C32—H32A | 0.97 |
C11—C51 | 1.503 (3) | C32—H32B | 0.97 |
C11—C21 | 1.513 (4) | O1W—H1W | 0.85 (4) |
C11—C31 | 1.525 (4) | O1W—H2W | 0.86 (4) |
O42—Na1—O21i | 89.54 (9) | C21—C31—H31B | 117.7 |
O42—Na1—O41i | 163.78 (9) | C11—C31—H31B | 117.7 |
O21i—Na1—O41i | 74.26 (8) | H31A—C31—H31B | 114.8 |
O42—Na1—O41ii | 101.48 (9) | O21—C41—O11 | 122.1 (2) |
O21i—Na1—O41ii | 155.79 (9) | O21—C41—C11 | 125.7 (2) |
O41i—Na1—O41ii | 93.90 (7) | O11—C41—C11 | 112.2 (2) |
O42—Na1—O1W | 91.34 (9) | O41—C51—O31 | 124.8 (2) |
O21i—Na1—O1W | 89.24 (9) | O41—C51—C11 | 124.1 (2) |
O41i—Na1—O1W | 87.70 (8) | O31—C51—C11 | 110.9 (2) |
O41ii—Na1—O1W | 111.72 (9) | C42—O22—H22 | 109 (4) |
O42—Na1—O21 | 95.42 (9) | C52—O42—Na1 | 142.02 (19) |
O21i—Na1—O21 | 78.33 (8) | C42—C12—C52 | 119.5 (2) |
O41i—Na1—O21 | 82.32 (8) | C42—C12—C32 | 116.4 (2) |
O41ii—Na1—O21 | 79.21 (8) | C52—C12—C32 | 116.0 (2) |
O1W—Na1—O21 | 165.77 (8) | C42—C12—C22 | 116.4 (2) |
C41—O11—H11 | 108 (4) | C52—C12—C22 | 116.4 (2) |
C41—O21—Na1i | 122.87 (17) | C32—C12—C22 | 57.1 (2) |
C41—O21—Na1 | 118.33 (18) | C32—C22—C12 | 61.39 (19) |
Na1i—O21—Na1 | 101.67 (8) | C32—C22—H22A | 117.6 |
C51—O31—H31 | 113 (4) | C12—C22—H22A | 117.6 |
C51—O41—Na1i | 130.55 (17) | C32—C22—H22B | 117.6 |
C51—O41—Na1iv | 142.66 (17) | C12—C22—H22B | 117.6 |
Na1i—O41—Na1iv | 86.10 (7) | H22A—C22—H22B | 114.7 |
C41—C11—C51 | 119.0 (2) | C22—C32—C12 | 61.5 (2) |
C41—C11—C21 | 115.9 (2) | C22—C32—H32A | 117.6 |
C51—C11—C21 | 117.8 (2) | C12—C32—H32A | 117.6 |
C41—C11—C31 | 116.9 (2) | C22—C32—H32B | 117.6 |
C51—C11—C31 | 114.9 (2) | C12—C32—H32B | 117.6 |
C21—C11—C31 | 57.6 (2) | H32A—C32—H32B | 114.7 |
C31—C21—C11 | 61.6 (2) | O12—C42—O22 | 121.9 (3) |
C31—C21—H21A | 117.6 | O12—C42—C12 | 121.9 (3) |
C11—C21—H21A | 117.6 | O22—C42—C12 | 116.1 (2) |
C31—C21—H21B | 117.6 | O32—C52—O42 | 124.4 (3) |
C11—C21—H21B | 117.6 | O32—C52—C12 | 118.3 (2) |
H21A—C21—H21B | 114.7 | O42—C52—C12 | 117.2 (2) |
C21—C31—C11 | 60.8 (2) | Na1—O1W—H1W | 99 (2) |
C21—C31—H31A | 117.7 | Na1—O1W—H2W | 129 (3) |
C11—C31—H31A | 117.7 | H1W—O1W—H2W | 100 (4) |
O42—Na1—O21—C41 | 49.41 (19) | C21—C11—C51—O41 | −172.1 (3) |
O21i—Na1—O21—C41 | 137.8 (2) | C31—C11—C51—O41 | 122.9 (3) |
O41i—Na1—O21—C41 | −146.76 (18) | C41—C11—C51—O31 | 160.1 (2) |
O41ii—Na1—O21—C41 | −51.28 (18) | C21—C11—C51—O31 | 11.0 (4) |
O1W—Na1—O21—C41 | 167.4 (3) | C31—C11—C51—O31 | −54.0 (3) |
Na1iii—Na1—O21—C41 | −99.11 (18) | O21i—Na1—O42—C52 | −167.9 (4) |
Na1i—Na1—O21—C41 | 137.8 (2) | O41i—Na1—O42—C52 | −170.7 (3) |
O42—Na1—O21—Na1i | −88.41 (9) | O41ii—Na1—O42—C52 | −9.6 (4) |
O41i—Na1—O21—Na1i | 75.43 (8) | O1W—Na1—O42—C52 | 102.9 (4) |
O41ii—Na1—O21—Na1i | 170.91 (9) | O21—Na1—O42—C52 | −89.7 (4) |
O1W—Na1—O21—Na1i | 29.6 (3) | Na1iii—Na1—O42—C52 | −16.7 (5) |
Na1iii—Na1—O21—Na1i | 123.07 (8) | Na1i—Na1—O42—C52 | −126.9 (4) |
C41—C11—C21—C31 | 106.7 (3) | C42—C12—C22—C32 | 105.6 (3) |
C51—C11—C21—C31 | −103.3 (3) | C52—C12—C22—C32 | −105.2 (3) |
C41—C11—C31—C21 | −105.0 (3) | C42—C12—C32—C22 | −105.7 (3) |
C51—C11—C31—C21 | 108.4 (3) | C52—C12—C32—C22 | 105.8 (3) |
Na1i—O21—C41—O11 | −135.2 (2) | C52—C12—C42—O12 | 177.4 (3) |
Na1—O21—C41—O11 | 96.4 (3) | C32—C12—C42—O12 | 30.1 (4) |
Na1i—O21—C41—C11 | 47.5 (3) | C22—C12—C42—O12 | −34.4 (4) |
Na1—O21—C41—C11 | −80.9 (3) | C52—C12—C42—O22 | −3.1 (4) |
C51—C11—C41—O21 | −1.4 (4) | C32—C12—C42—O22 | −150.4 (3) |
C21—C11—C41—O21 | 148.3 (3) | C22—C12—C42—O22 | 145.1 (3) |
C31—C11—C41—O21 | −146.7 (3) | Na1—O42—C52—O32 | 11.3 (6) |
C51—C11—C41—O11 | −178.9 (2) | Na1—O42—C52—C12 | −170.4 (2) |
C21—C11—C41—O11 | −29.3 (3) | C42—C12—C52—O32 | −179.7 (3) |
C31—C11—C41—O11 | 35.8 (3) | C32—C12—C52—O32 | −32.3 (4) |
Na1i—O41—C51—O31 | 173.4 (2) | C22—C12—C52—O32 | 32.0 (4) |
Na1iv—O41—C51—O31 | 6.5 (5) | C42—C12—C52—O42 | 1.9 (4) |
Na1i—O41—C51—C11 | −3.1 (4) | C32—C12—C52—O42 | 149.3 (3) |
Na1iv—O41—C51—C11 | −170.0 (2) | C22—C12—C52—O42 | −146.4 (3) |
C41—C11—C51—O41 | −23.0 (4) |
Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) x−1, y, z; (iii) −x, −y+1, −z+2; (iv) x+1, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O22—H22···O42 | 0.93 (6) | 1.56 (6) | 2.429 (3) | 154 (5) |
O1W—H2W···O12v | 0.86 (4) | 1.90 (4) | 2.737 (3) | 162 (4) |
O1W—H1W···O22ii | 0.85 (4) | 1.98 (4) | 2.777 (4) | 155 (3) |
O11—H11···O1Wiii | 0.77 (5) | 1.88 (5) | 2.642 (3) | 170 (5) |
O31—H31···O32iv | 0.72 (6) | 1.80 (6) | 2.478 (3) | 155 (6) |
Symmetry codes: (ii) x−1, y, z; (iii) −x, −y+1, −z+2; (iv) x+1, y, z; (v) −x+1, −y, −z+2. |
Experimental details
Crystal data | |
Chemical formula | Na+·C5H5O4−·C5H4O4·H2O |
Mr | 300.19 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 5.2910 (13), 10.118 (3), 12.895 (5) |
α, β, γ (°) | 109.44 (3), 98.64 (2), 99.57 (2) |
V (Å3) | 626.0 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.17 |
Crystal size (mm) | 0.48 × 0.22 × 0.16 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3932, 2985, 1654 |
Rint | 0.047 |
(sin θ/λ)max (Å−1) | 0.661 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.051, 0.150, 0.99 |
No. of reflections | 2985 |
No. of parameters | 202 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.31, −0.36 |
Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1994), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1998).
Na1—O42 | 2.261 (2) | O41—C51 | 1.207 (3) |
Na1—O21i | 2.325 (2) | C11—C21 | 1.513 (4) |
Na1—O41i | 2.370 (2) | C11—C31 | 1.525 (4) |
Na1—O41ii | 2.384 (2) | C21—C31 | 1.464 (5) |
Na1—O1W | 2.526 (3) | O12—C42 | 1.215 (3) |
Na1—O21 | 2.533 (2) | O22—C42 | 1.298 (4) |
Na1—Na1iii | 3.245 (2) | O32—C52 | 1.233 (3) |
Na1—Na1i | 3.769 (3) | O42—C52 | 1.258 (3) |
O11—C41 | 1.320 (3) | C12—C32 | 1.518 (4) |
O21—C41 | 1.204 (3) | C12—C22 | 1.520 (4) |
O31—C51 | 1.301 (3) | C22—C32 | 1.451 (5) |
C51—C11—C41—O21 | −1.4 (4) | C52—C12—C42—O22 | −3.1 (4) |
C41—C11—C51—O41 | −23.0 (4) | C42—C12—C52—O42 | 1.9 (4) |
Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) x−1, y, z; (iii) −x, −y+1, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O22—H22···O42 | 0.93 (6) | 1.56 (6) | 2.429 (3) | 154 (5) |
O1W—H2W···O12iv | 0.86 (4) | 1.90 (4) | 2.737 (3) | 162 (4) |
O1W—H1W···O22ii | 0.85 (4) | 1.98 (4) | 2.777 (4) | 155 (3) |
O11—H11···O1Wiii | 0.77 (5) | 1.88 (5) | 2.642 (3) | 170 (5) |
O31—H31···O32v | 0.72 (6) | 1.80 (6) | 2.478 (3) | 155 (6) |
Symmetry codes: (ii) x−1, y, z; (iii) −x, −y+1, −z+2; (iv) −x+1, −y, −z+2; (v) x+1, y, z. |
Acknowledgements
The authors thank the EPSRC, UK, and the University of Glasgow for support.
References
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The cyclopropane-1,1-dicarboxylic acid molecule, (1), hereinafter LH2, where L is C2H4C(CO2)2, contains an internal O—H···O hydrogen bond (see scheme) and in consequence, its monoanion LH−, (2), is a very weak acid (Meester et al., 1971). The LH− anions of the related acid salt K(LH)·0.5H2O are also stabilized by internal O—H···O hydrogen bonds (Dubourg et al., 1990). We now report that our attempt to prepare the analogous sodium salt Na(LH)·0.5H2O has instead produced the title compound, Na(LH)(LH2)·H2O, (I). \sch
Crystals of (I) are built up from Na+ cations, LH− anions, molecules of the neutral acid and water. The LH− anions (Fig. 1 b) contain an internal O—H···O hydrogen bond which is even shorter [O···O 2.429 (3) Å] than the corresponding bond in the free acid (2.563 Å). The internal O—H···O hydrogen bonds in the LH2 molecule (Meester et al., 1971) and in the LH− anions of (I) and K(LH)·0.5H2O (Dubourg et al., 1990) all have ordered H atoms conventionally bonded to one of the O atoms. This contrasts with [Co(H2O)6][LH]2, where the anions straddle crystallographic mirror planes so that the acidic H atom is either equidistant from the two O atoms or is disordered (Schwartz et al., 1998).
The LH2 molecules of (I) (Fig. 1a) have near C2v symmetry but adopt conformation (3), which precludes internal hydrogen bonding [O21···O41 2.834 (3) Å]. The geometries of the LH2 molecule and LH− anion (Table 1) show typical features (see, for example, Meester et al., 1971; Dubourg et al., 1990; Muir et al., 2000; Schwartz et al., 1998). Firstly, pairs of C—O bond lengths differ by > 0.08 Å in CO2H groups and by < 0.02 (5) Å in CO2− groups. Secondly, an electronic effect of the carboxyl substituents shortens the distal C2n—C3n (n = 1, 2) ring bonds by 0.05–0.07 Å relative to the other C—C bonds in the cyclopropane rings. Finally, they adopt Please check added text conformations which make each carboxyl group nearly coincide with the plane normal to C2n—C3n passing through C1n; the C51 carboxyl group is an exception, as can be seen by comparing the C41—C11—C51—O41 torsion angle with the others in Table 1.
The crystal of (I) is built from kinked chains of identical NaO6 octahedra (Table 1 and Fig. 2a), which are axially elongated along the O21—Na1—O1W direction and linked via edges which pass through crystallographic inversion centres. Atom Na1 shares octahedral edges with atoms Na1i and Na1iii, themselves related directly by translation along the a axis which thus defines the direction of the chains [symmetry codes: (i) 1 − x, 1 − y, 2 − z; (iii) −x, 1 − y, 2 − z].
Atom Na1 bonds to three different LH2 molecules, one water molecule and one LH− anion. In consequence, the LH2 molecule participates in four Na—O bonds (Fig. 2 b), with atom O2i bonded to both atoms Na1 and Nai, and atom O41i shared between atoms Na1 and Naiii. The LH− anion is attached to only one cation, through atom O42, which is part of the ionized carboxyl group. Similarly, the water atom O1W bonds to only one Na+ cation. Each acid molecule is also the donor in two O—H···O hydrogen bonds (Table 2), namely a very strong bond [O···O 2.478 (3) Å] to the LH− anion and a weaker one [O···O 2.642 (3) Å] to a water molecule. Atom O22 accepts a hydrogen bond from atom O1W. The resulting arrangement surrounds atoms Na1 and Na1iii by a roughly planar belt containing an (LH2—LH−—H2O)2 ring, in which the individual molecules and anions are joined by hydrogen bonds. Not shown in Fig. 2(b) are the O1W—H···O12 hydrogen bonds, which link together the chains of octahedra.
The crystal architecture uses all five available O—H groups as hydrogen-bond donors, two of these bonds being very short (O···O < 2.50 Å). In each independent O—H···O bond, the two O atoms are unrelated by crystallographic symmetry. Compound (I) is therefore a B2 acid salt in the classification of Speakman (1972).
It is tempting to ascribe the different stoichiometries of the sodium and potassium acid salts of cyclopropane-1,1-dicarboxylic acid to the different ionic radii of K+ and Na+. However, in the case of malonic acid, L'H2, where L' is CH2(CO2)2, a similar difference is the result of a solvent isotope effect: the salts Na(L'H) and Na(L'H)(LH2) can be produced by identical procedures, but using D2O as the solvent gives partially deuterated Na(L'H)(L'H2), whereas H2O gives Na(L'H) (Kalsbeek, 1992).