catena-Poly[[[triaqua­cadmium(II)]-μ-3-carboxyl­atophenoxy­acetato-κ³O³,O^3′:O′′] sesquihydrate]

The dicarboxyl­ate ligand in the title compound, [Cd(C₉H₆O₅)(H₂O)₃]·1.5H₂O, bridges triaqua­cadmium groups into a linear chain; the carboxylate arm that is directly connected to the aromatic ring behaves as a chelate, whereas the carboxylate arm of the oxyacetate portion binds in a monodentate mode. The octa­hedral environment of cadmium is distorted towards a penta­gonal bipyramid, owing to a long Cd...O inter­action of 2.721 (2) Å.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.004 Å
• H-atom completeness 81%
• Disorder in solvent or counterion
• R factor = 0.028
• wR factor = 0.067
• Data-to-parameter ratio = 15.4

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT430_ALERT_2_A Short Inter D...A Contact  O4W    ..  O5W     ..       1.97 Ang.

Author Response: The O4w and O5w atoms are disordered. The O4w atom is 3 \%A from O5w^ii^ whereas the O4w' atom is 2.7 \%A from O5w (ii = 3 - x, 2 - y, 1 - z).

Alert level B
PLAT430_ALERT_2_B Short Inter D...A Contact  O1     ..  O5W     ..       2.81 Ang.

Author Response: The O4w and O5w atoms are disordered. The O4w atom is 3 \%A from O5w^ii^ whereas the O4w' atom is 2.7 \%A from O5w (ii = 3 - x, 2 - y, 1 - z).

PLAT430_ALERT_2_B Short Inter D...A Contact  O4W'   ..  O5W     ..       2.70 Ang.

Author Response: The O4w and O5w atoms are disordered. The O4w atom is 3 \%A from O5w^ii^ whereas the O4w' atom is 2.7 \%A from O5w (ii = 3 - x, 2 - y, 1 - z).

PLAT430_ALERT_2_B Short Inter D...A Contact  O4W'   ..  O5      ..       2.71 Ang.

Author Response: The O4w and O5w atoms are disordered. The O4w atom is 3 \%A from O5w^ii^ whereas the O4w' atom is 2.7 \%A from O5w (ii = 3 - x, 2 - y, 1 - z).

Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
            Tmin and Tmax reported:      0.460     0.753
            Tmin(prime) and Tmax expected:      0.542     0.741
            RR(prime) =      0.835
            Please check that your absorption correction is appropriate.
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.97
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.50 Ratio
PLAT061_ALERT_3_C Tmax/Tmin Range Test RR' too Large .............       0.82
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.98
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing)...          ?
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.13
PLAT302_ALERT_4_C Anion/Solvent Disorder .........................      50.00 Perc.
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          7

Alert level G
FORMU01_ALERT_2_G  There is a discrepancy between the atom counts in the
            _chemical_formula_sum and the formula from the _atom_site* data.
            Atom count from _chemical_formula_sum:C9 H15 Cd1 O9.5
            Atom count from the _atom_site data:  C9 H12 Cd1 O9.5
CELLZ01_ALERT_1_G Difference between formula and atom_site contents detected.
CELLZ01_ALERT_1_G WARNING: H atoms missing from atom site list. Is this intentional?
           From the CIF: _cell_formula_units_Z    2
           From the CIF: _chemical_formula_sum  C9 H15 Cd O9.50
           TEST: Compare cell contents of formula and atom_site data

           atom    Z*formula  cif sites diff
           C         18.00     18.00    0.00
           H         30.00     24.00    6.00
           Cd         2.00      2.00    0.00
           O         19.00     19.00    0.00

   1 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
  12 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

   7 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   6 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion

---

S1. Comment

A recent study on the cadmium derivative of 4-carboxyphenoxyacetic acid describes the isolation of a triaqua compound whose seven-coordinate metal exists in a pentagonal bipyramidal environment. Both carboxyl –CO₂ arms of the dicarboxylate function in the chelating mode, with the four Cd–O bond distances ranging from 2.356 (2) to 2.444 (2) Å (Gao et al., 2005). The corresponding 3-carboxyphenoxyacetic acid also affords a triaquacadmium compound. However, probably owing to the greater flexibility of the ligand, the packing is less efficient so that the compound crystallizes with one-and-a-half uncoordinated water molecules (Scheme, Fig. 1). The compound exists as a linear chain that propagates along the longest axis of the unit cell. Ofn the two carboxyl arms, that connected to the aromatic ring functions as a chelate whereas that belonging to the oxyacetate portion is only unidentate. However, a long-range interaction betweenCd1 and O5 is sufficiently close [2.721 (2) Å] to distort the octahedral geometry to a pentagonal bipyramid. The chains are linked by hydrogen bonds (Table 2) into a three-dimensional network.

S2. Experimental

Cadmium dinitrate tetrahydrate (0.62 g, 2 mmol) and 3-carboxyphenoxyacetic acid (0.39 g, 2 mmol) were dissolved in a small volume of water (30 ml); 0.2 M sodium hydroxide was added in drops to the solution until it showed a pH of 6. The solution was set aside for the formation of colorless prisms; crystallization took several weeks. C&H analysis. Calc. for C₉H₁₅O_9.5Cd: C 27.89, H 3.90%. Found: C 27.16, H 4.03%.

S3. Refinement

The carbon-bound H atoms were positioned geometrically [C–H 0.93 or 0.97 Å] and were included in the refinement in the riding-model approximation, with U(H) = 1.2 times U_eq(C). The H atoms of the coordinated water molecules were similarly treated [O–H 0.85 Å, U(H) = 1.5U_eq(O)]; these were rotated to fit the electron density.

Of the two independent uncoordinated water molecules, one is disordered over two positions (O4w and O4w') while the other is disordered over an inversion site (O5w). A consideration of possible hydrogen-bonding interactions led to the assignment of half occupancies for these atoms. H atoms could not be placed in any chemically sensible positions owing to the disorder. O4w is 3 Å from O5wⁱⁱ while O4w' is 2.7 Å from O5w [symmetry code: (ii) = 3 − x, 2 − y, 1 − z].

Computing details

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. ORTEPII plot of a portion of the chain structure of [(C9H6O5)(H2O)3Cd]^.1.5H2O; the disordered uncoordinated water molecules are not shown. Displacement ellipsoids are drawn at the 50% probability level, and H atoms are drawn as spheres of arbitrary radii. [Symmetry code: (i) = x, y, 1 + z.]

catena-Poly[(µ-3-carboxylatophenoxyacetato-κ³O,O':O")triaquacadmium(II) sesquihydrate]

Crystal data

[Cd(C9H6O5)(H2O)3]·1.5H2O	Z = 2
Mr = 387.61	F(000) = 386
Triclinic, P1	Dx = 1.916 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.029 (1) Å	Cell parameters from 5430 reflections
b = 8.829 (2) Å	θ = 3.1–27.5°
c = 11.720 (2) Å	µ = 1.67 mm^−1
α = 80.62 (3)°	T = 295 K
β = 72.66 (3)°	Block, colorless
γ = 76.52 (3)°	0.36 × 0.25 × 0.18 mm
V = 671.7 (2) Å^3

Data collection

Rigaku RAXIS-RAPID IP diffractometer	2969 independent reflections
Radiation source: fine-focus sealed tube	2671 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
ω scans	θmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −9→9
Tmin = 0.460, Tmax = 0.753	k = −11→11
5896 measured reflections	l = −15→14

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.067	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0358P)^2 + 0.544P] where P = (Fo^2 + 2Fc^2)/3
2969 reflections	(Δ/σ)max = 0.001
193 parameters	Δρmax = 0.71 e Å^−3
0 restraints	Δρmin = −0.57 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cd1	0.72063 (3)	0.71871 (2)	0.93308 (2)	0.0336 (1)
O1	0.6866 (4)	0.6999 (3)	0.7345 (2)	0.048 (1)
O2	0.7597 (4)	0.4883 (2)	0.8533 (2)	0.039 (1)
O3	0.7641 (3)	0.4861 (2)	0.3357 (2)	0.034 (1)
O4	0.7316 (4)	0.5846 (3)	0.1154 (2)	0.043 (1)
O5	0.6830 (4)	0.8331 (3)	0.1424 (2)	0.052 (1)
O1w	1.0684 (4)	0.7203 (3)	0.8760 (2)	0.047 (1)
O2w	0.6953 (4)	0.9776 (2)	0.8698 (2)	0.042 (1)
O3w	0.3567 (4)	0.7618 (3)	1.0025 (2)	0.042 (1)
O4w	1.325 (1)	0.9316 (9)	0.6996 (6)	0.059 (2)	0.50
O4w'	1.231 (2)	0.951 (1)	0.7500 (8)	0.095 (3)	0.50
O5w	1.570 (1)	0.9375 (9)	0.5640 (7)	0.090 (2)	0.50
C1	0.7313 (4)	0.5544 (3)	0.7528 (2)	0.032 (1)
C2	0.7616 (4)	0.4528 (3)	0.6550 (2)	0.027 (1)
C3	0.8204 (4)	0.2920 (3)	0.6745 (2)	0.031 (1)
C4	0.8578 (5)	0.1995 (3)	0.5820 (3)	0.036 (1)
C5	0.8373 (5)	0.2685 (3)	0.4697 (2)	0.034 (1)
C6	0.7771 (4)	0.4293 (3)	0.4505 (2)	0.027 (1)
C7	0.7375 (4)	0.5233 (3)	0.5426 (2)	0.027 (1)
C8	0.7096 (4)	0.6500 (3)	0.3109 (2)	0.029 (1)
C9	0.7095 (4)	0.6906 (4)	0.1799 (2)	0.034 (1)
H1w1	1.0942	0.7910	0.8183	0.071*
H1w2	1.1348	0.6316	0.8537	0.071*
H2w1	0.7055	1.0258	0.9242	0.064*
H2w2	0.5809	1.0138	0.8551	0.064*
H3w1	0.3211	0.6849	1.0518	0.063*
H3w2	0.3079	0.7704	0.9431	0.063*
H3	0.8348	0.2459	0.7494	0.037*
H4	0.8965	0.0914	0.5951	0.044*
H5	0.8639	0.2066	0.4075	0.041*
H7	0.6958	0.6312	0.5298	0.033*
H8a	0.8056	0.7005	0.3278	0.034*
H8b	0.5756	0.6879	0.3621	0.034*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0548 (2)	0.0268 (1)	0.0226 (1)	−0.0072 (1)	−0.0169 (1)	−0.0011 (1)
O1	0.085 (2)	0.035 (1)	0.029 (1)	−0.013 (1)	−0.023 (1)	−0.005 (1)
O2	0.063 (1)	0.041 (1)	0.023 (1)	−0.017 (1)	−0.019 (1)	−0.002 (1)
O3	0.053 (1)	0.031 (1)	0.019 (1)	−0.003 (1)	−0.016 (1)	−0.003 (1)
O4	0.061 (1)	0.046 (1)	0.024 (1)	−0.004 (1)	−0.021 (1)	−0.004 (1)
O5	0.068 (2)	0.042 (1)	0.044 (1)	−0.009 (1)	−0.024 (1)	0.012 (1)
O1w	0.059 (1)	0.039 (1)	0.047 (1)	0.002 (1)	−0.024 (1)	−0.010 (1)
O2w	0.061 (1)	0.029 (1)	0.039 (1)	−0.007 (1)	−0.019 (1)	−0.001 (1)
O3w	0.058 (1)	0.040 (1)	0.035 (1)	−0.013 (1)	−0.023 (1)	0.001 (1)
O4w	0.073 (5)	0.056 (3)	0.056 (4)	−0.018 (3)	−0.022 (3)	−0.010 (3)
O4w'	0.120 (8)	0.084 (6)	0.088 (6)	−0.071 (6)	0.006 (5)	−0.016 (5)
O5w	0.093 (5)	0.084 (5)	0.088 (5)	−0.018 (4)	−0.025 (4)	0.013 (4)
C1	0.038 (2)	0.039 (2)	0.025 (1)	−0.013 (1)	−0.010 (1)	−0.005 (1)
C2	0.029 (1)	0.036 (1)	0.019 (1)	−0.011 (1)	−0.007 (1)	−0.003 (1)
C3	0.037 (1)	0.037 (1)	0.020 (1)	−0.009 (1)	−0.011 (1)	0.001 (1)
C4	0.050 (2)	0.028 (1)	0.031 (1)	−0.003 (1)	−0.014 (1)	−0.001 (11)
C5	0.046 (2)	0.034 (1)	0.025 (1)	−0.004 (1)	−0.013 (1)	−0.009 (1)
C6	0.030 (1)	0.036 (1)	0.017 (1)	−0.007 (1)	−0.008 (1)	−0.002 (1)
C7	0.032 (1)	0.030 (1)	0.021 (1)	−0.006 (1)	−0.010 (1)	−0.002 (1)
C8	0.035 (1)	0.031 (1)	0.022 (1)	−0.007 (1)	−0.012 (1)	−0.001 (1)
C9	0.036 (2)	0.043 (2)	0.023 (1)	−0.007 (1)	−0.013 (1)	0.003 (1)

Geometric parameters (Å, º)

Cd1—O1	2.445 (2)	C4—C5	1.391 (4)
Cd1—O2	2.301 (2)	C5—C6	1.385 (4)
Cd1—O4^i	2.281 (2)	C6—C7	1.392 (4)
Cd1—O1w	2.337 (3)	C8—C9	1.519 (3)
Cd1—O2w	2.268 (2)	O1w—H1w1	0.85
Cd1—O3w	2.399 (2)	O1w—H1w2	0.85
O1—C1	1.248 (4)	O2w—H2w1	0.85
O2—C1	1.277 (3)	O2w—H2w2	0.85
O3—C6	1.379 (3)	O3w—H3w1	0.85
O3—C8	1.413 (3)	O3w—H3w2	0.85
O4—C9	1.250 (4)	C3—H3	0.93
O5—C9	1.253 (4)	C4—H4	0.93
C1—C2	1.504 (4)	C5—H5	0.93
C2—C3	1.384 (4)	C7—H7	0.93
C2—C7	1.403 (3)	C8—H8a	0.97
C3—C4	1.390 (4)	C8—H8b	0.97
O1—Cd1—O2	55.0 (1)	O3—C6—C7	124.0 (2)
O1—Cd1—O4^i	144.6 (1)	C5—C6—C7	120.6 (2)
O1—Cd1—O1w	97.7 (1)	C6—C7—C2	119.0 (2)
O1—Cd1—O2w	83.8 (1)	O3—C8—C9	109.8 (2)
O1—Cd1—O3w	87.2 (1)	O4—C9—O5	123.0 (3)
O2—Cd1—O4^i	90.6 (1)	O4—C9—C8	120.3 (3)
O2—Cd1—O1w	94.3 (1)	O5—C9—C8	116.7 (3)
O2—Cd1—O2w	138.2 (1)	Cd1—O1w—H1w1	109.5
O2—Cd1—O3w	95.7 (1)	Cd1—O1w—H1w2	109.5
O4^i—Cd1—O1w	92.8 (1)	H1w1—O1w—H1w2	109.5
O4^i—Cd1—O2w	131.2 (1)	Cd1—O2w—H2w1	109.5
O4^i—Cd1—O3w	88.2 (1)	Cd1—O2w—H2w2	109.5
O1w—Cd1—O2w	83.1 (1)	H2w1—O2w—H2w2	109.5
O1w—Cd1—O3w	169.9 (1)	Cd1—O3w—H3w1	109.5
O2w—Cd1—O3w	88.7 (1)	Cd1—O3w—H3w2	109.5
C1—O1—Cd1	89.0 (2)	H3w1—O3w—H3w2	109.5
C1—O2—Cd1	94.9 (2)	C2—C3—H3	120.0
C6—O3—C8	117.4 (2)	C4—C3—H3	120.0
C9—O4—Cd1^ii	103.3 (2)	C3—C4—H4	120.0
O1—C1—O2	120.9 (3)	C5—C4—H4	120.0
O1—C1—C2	120.7 (2)	C6—C5—H5	120.0
O2—C1—C2	118.3 (3)	C4—C5—H5	120.0
C3—C2—C7	120.5 (2)	C6—C7—H7	120.5
C3—C2—C1	120.2 (2)	C2—C7—H7	120.5
C7—C2—C1	119.3 (2)	O3—C8—H8a	109.7
C2—C3—C4	119.9 (2)	C9—C8—H8a	109.7
C3—C4—C5	120.0 (3)	O3—C8—H8b	109.7
C6—C5—C4	120.0 (2)	C9—C8—H8b	109.7
O3—C6—C5	115.4 (2)	H8a—C8—H8b	108.2
O2w—Cd1—O1—C1	170.1 (2)	C7—C2—C3—C4	0.6 (4)
O4^i—Cd1—O1—C1	−17.8 (3)	C1—C2—C3—C4	−176.9 (3)
O2—Cd1—O1—C1	−2.0 (2)	C2—C3—C4—C5	0.3 (4)
O1w—Cd1—O1—C1	88.0 (2)	C3—C4—C5—C6	−0.8 (5)
O3w—Cd1—O1—C1	−100.9 (2)	C8—O3—C6—C5	−178.0 (2)
O2w—Cd1—O2—C1	−9.9 (2)	C8—O3—C6—C7	0.8 (4)
O4^i—Cd1—O2—C1	172.8 (2)	C4—C5—C6—O3	179.1 (3)
O1w—Cd1—O2—C1	−94.4 (2)	C4—C5—C6—C7	0.3 (4)
O3w—Cd1—O2—C1	84.6 (2)	O3—C6—C7—C2	−178.1 (2)
O1—Cd1—O2—C1	1.9 (2)	C5—C6—C7—C2	0.7 (4)
Cd1—O1—C1—O2	3.4 (3)	C3—C2—C7—C6	−1.1 (4)
Cd1—O1—C1—C2	−174.0 (2)	C1—C2—C7—C6	176.4 (2)
Cd1—O2—C1—O1	−3.6 (3)	C6—O3—C8—C9	178.3 (2)
Cd1—O2—C1—C2	173.8 (2)	Cd1^ii—O4—C9—O5	1.8 (4)
O1—C1—C2—C3	177.0 (3)	Cd1^ii—O4—C9—C8	−179.5 (2)
O2—C1—C2—C3	−0.5 (4)	O3—C8—C9—O4	7.9 (4)
O1—C1—C2—C7	−0.5 (4)	O3—C8—C9—O5	−173.3 (3)
O2—C1—C2—C7	−178.0 (2)

Symmetry codes: (i) x, y, z+1; (ii) x, y, z−1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1w—H1w1···O4w	0.85	2.27	3.015 (8)	147
O1w—H1w1···O4w′	0.85	1.83	2.593 (8)	148
O1w—H1w2···O4^iii	0.85	1.95	2.732 (3)	153
O2w—H2w1···O3w^iv	0.85	2.09	2.841 (3)	147
O2w—H2w2···O5^v	0.85	2.02	2.821 (4)	157
O3w—H3w2···O1w^vi	0.85	2.21	2.959 (3)	147
O3w—H3w1···O2^vii	0.85	1.84	2.684 (3)	175

Symmetry codes: (iii) −x+2, −y+1, −z+1; (iv) −x+1, −y+2, −z+2; (v) −x+1, −y+2, −z+1; (vi) x−1, y, z; (vii) −x+1, −y+1, −z+2.