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In the title complex, {[Cu(C6H5O3)Cl(H2O)]·H2O}n, the CuII atom has a deformed square-pyramidal coordination geometry formed by two O atoms of the maltolate ligand, two bridging Cl atoms and the coordinated water O atom. The Cu atoms are bridged by Cl atoms to form a polymeric chain. The deprotonated hydroxyl and ketone O atoms of the maltolate ligand form a five-membered chelate ring with the Cu atom. Stacking interactions and hydrogen bonds exist in the crystal.
Supporting information
CCDC reference: 197319
Maltol and CuCl2·2H2O were dissolved in a 50% ethanol–water mixture in
a 4:1 molar ratio. Green plate-shaped crystals of (II) were obtained by slow
evaporation at room temperature.
The H atoms of the ligand molecule were allowed for as riding atoms. Those of
water molecules were located from difference Fourier maps and their
coordinates refined with fixed isotropic vibration parameters.
Data collection: MSC/AFC Diffractometer Control (Molecular Structure Corporation, 1992); cell refinement: MSC/AFC Diffractometer Control; data reduction: TEXSAN (Molecular Structure Corporation, 2000); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP II (Johnson, 1976); software used to prepare material for publication: TEXSAN.
Crystal data top
[Cu(C6H5O3)Cl(H2O)]·H2O | F(000) = 524 |
Mr = 260.13 | Dx = 1.920 Mg m−3 |
Monoclinic, P21/a | Mo Kα radiation, λ = 0.7107 Å |
Hall symbol: -P 2yab | Cell parameters from 22 reflections |
a = 7.163 (2) Å | θ = 14.6–15.0° |
b = 18.604 (2) Å | µ = 2.71 mm−1 |
c = 7.357 (2) Å | T = 296 K |
β = 113.38 (2)° | Plate, green |
V = 899.9 (4) Å3 | 0.40 × 0.20 × 0.10 mm |
Z = 4 | |
Data collection top
Rigaku AFC-5R diffractometer | Rint = 0.009 |
ω–2θ scans | θmax = 27.5°, θmin = 3.0° |
Absorption correction: ψ scan (North et al., 1968) | h = 0→9 |
Tmin = 0.527, Tmax = 0.763 | k = 0→24 |
2302 measured reflections | l = −9→8 |
2069 independent reflections | 3 standard reflections every 150 reflections |
1778 reflections with I > 2σ(I) | intensity decay: 0.5% |
Refinement top
Refinement on F2 | w = 1/[σ2(Fo2) + (0.027P)2 + 0.3833P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.021 | (Δ/σ)max = 0.001 |
wR(F2) = 0.058 | Δρmax = 0.34 e Å−3 |
S = 1.07 | Δρmin = −0.28 e Å−3 |
2069 reflections | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
132 parameters | Extinction coefficient: 0.0047 (8) |
H atoms treated by a mixture of independent and constrained refinement | |
Crystal data top
[Cu(C6H5O3)Cl(H2O)]·H2O | V = 899.9 (4) Å3 |
Mr = 260.13 | Z = 4 |
Monoclinic, P21/a | Mo Kα radiation |
a = 7.163 (2) Å | µ = 2.71 mm−1 |
b = 18.604 (2) Å | T = 296 K |
c = 7.357 (2) Å | 0.40 × 0.20 × 0.10 mm |
β = 113.38 (2)° | |
Data collection top
Rigaku AFC-5R diffractometer | 1778 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.009 |
Tmin = 0.527, Tmax = 0.763 | 3 standard reflections every 150 reflections |
2302 measured reflections | intensity decay: 0.5% |
2069 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.021 | 132 parameters |
wR(F2) = 0.058 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.34 e Å−3 |
2069 reflections | Δρmin = −0.28 e Å−3 |
Special details top
Refinement. Refinement using reflections with F2 > -10.0 σ(F2). The
weighted R-factor (wR) and goodness of fit (S) are based
on F2. R-factor (gt) are based on F. The threshold
expression of F2 > 2.0 σ(F2) is used only for calculating
R-factor (gt). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cl1 | 0.15307 (8) | 0.29022 (3) | 0.79480 (7) | 0.0319 (1) | |
Cu1 | 0.29255 (4) | 0.18032 (1) | 0.83113 (3) | 0.02541 (9) | |
O1 | 0.1738 (2) | −0.01327 (8) | 0.3219 (2) | 0.0350 (3) | |
O2 | 0.3677 (2) | 0.07854 (7) | 0.8616 (2) | 0.0333 (3) | |
O3 | 0.1566 (2) | 0.15755 (7) | 0.5507 (2) | 0.0272 (3) | |
O4W | 0.4171 (2) | 0.18564 (8) | 1.1217 (2) | 0.0321 (3) | |
O5W | 0.7954 (2) | 0.23087 (9) | 1.3565 (2) | 0.0337 (3) | |
C1 | 0.3117 (3) | 0.0479 (1) | 0.6938 (3) | 0.0256 (4) | |
C2 | 0.1949 (3) | 0.0891 (1) | 0.5207 (3) | 0.0241 (4) | |
C3 | 0.1290 (3) | 0.0572 (1) | 0.3388 (3) | 0.0290 (4) | |
C4 | 0.2865 (3) | −0.0518 (1) | 0.4834 (3) | 0.0355 (5) | |
C5 | 0.3568 (3) | −0.0246 (1) | 0.6671 (3) | 0.0323 (4) | |
C6 | 0.0068 (4) | 0.0906 (1) | 0.1453 (3) | 0.0401 (5) | |
H4 | 0.3168 | −0.0993 | 0.4667 | 0.0426* | |
H4WA | 0.369 (4) | 0.212 (1) | 1.175 (4) | 0.0385* | |
H4WB | 0.534 (3) | 0.197 (1) | 1.170 (4) | 0.0385* | |
H5 | 0.4339 | −0.0528 | 0.7754 | 0.0388* | |
H5WA | 0.774 (4) | 0.257 (1) | 1.428 (4) | 0.0404* | |
H5WB | 0.895 (3) | 0.209 (1) | 1.420 (4) | 0.0404* | |
H6A | 0.0750 | 0.0843 | 0.0573 | 0.0481* | |
H6B | −0.0093 | 0.1410 | 0.1635 | 0.0481* | |
H6C | −0.1245 | 0.0681 | 0.0895 | 0.0481* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cl1 | 0.0350 (3) | 0.0259 (2) | 0.0323 (3) | 0.0043 (2) | 0.0107 (2) | −0.0013 (2) |
Cu1 | 0.0315 (1) | 0.0223 (1) | 0.0179 (1) | 0.00096 (9) | 0.0049 (1) | −0.00092 (8) |
O1 | 0.0450 (9) | 0.0291 (7) | 0.0298 (8) | −0.0012 (7) | 0.0137 (7) | −0.0091 (6) |
O2 | 0.0474 (8) | 0.0248 (7) | 0.0204 (7) | 0.0026 (6) | 0.0057 (6) | 0.0014 (5) |
O3 | 0.0329 (7) | 0.0226 (6) | 0.0194 (6) | 0.0030 (6) | 0.0033 (5) | −0.0014 (5) |
O4W | 0.0339 (8) | 0.0368 (8) | 0.0212 (7) | 0.0003 (7) | 0.0062 (6) | −0.0046 (6) |
O5W | 0.0308 (8) | 0.0438 (9) | 0.0219 (7) | 0.0024 (7) | 0.0055 (6) | −0.0027 (6) |
C1 | 0.0278 (9) | 0.0231 (9) | 0.0247 (9) | −0.0012 (7) | 0.0091 (8) | 0.0013 (7) |
C2 | 0.0250 (9) | 0.0230 (9) | 0.0225 (9) | 0.0002 (7) | 0.0073 (7) | 0.0006 (7) |
C3 | 0.032 (1) | 0.0275 (10) | 0.0256 (9) | −0.0019 (8) | 0.0094 (8) | −0.0039 (8) |
C4 | 0.045 (1) | 0.0219 (9) | 0.042 (1) | 0.0033 (9) | 0.020 (1) | −0.0017 (8) |
C5 | 0.038 (1) | 0.0235 (9) | 0.033 (1) | 0.0033 (8) | 0.0114 (9) | 0.0035 (8) |
C6 | 0.049 (1) | 0.043 (1) | 0.0208 (9) | 0.000 (1) | 0.0067 (9) | −0.0029 (9) |
Geometric parameters (Å, º) top
Cl1—Cu1 | 2.2445 (6) | O5W—H5WB | 0.79 (2) |
Cl1—Cu1i | 2.7546 (9) | C1—C2 | 1.437 (2) |
Cu1—O2 | 1.957 (1) | C1—C5 | 1.418 (3) |
Cu1—O3 | 1.947 (1) | C2—C3 | 1.365 (3) |
Cu1—O4W | 1.965 (1) | C3—C6 | 1.480 (3) |
O1—C3 | 1.367 (3) | C4—C5 | 1.340 (3) |
O1—C4 | 1.348 (2) | C4—H4 | 0.930 |
O2—C1 | 1.272 (2) | C5—H5 | 0.930 |
O3—C2 | 1.339 (2) | C6—H6A | 0.960 |
O4W—H4WA | 0.786 (19) | C6—H6B | 0.960 |
O4W—H4WB | 0.798 (19) | C6—H6C | 0.960 |
O5W—H5WA | 0.772 (19) | | |
| | | |
Cl1···O2i | 3.343 (2) | O3···O5Wii | 2.768 (2) |
Cl1···O5Wii | 3.409 (1) | O3···O5Wviii | 2.910 (2) |
Cl1···O3i | 3.428 (2) | O4W···O5Wi | 2.711 (3) |
Cl1···O4Wi | 3.474 (2) | O4W···C5vii | 3.467 (3) |
Cl1···C6iii | 3.578 (2) | O4W···C6ix | 3.492 (3) |
O1···C5iv | 3.405 (3) | C2···C4vi | 3.506 (3) |
O1···C6v | 3.467 (3) | C3···C5vi | 3.515 (4) |
O1···C1vi | 3.493 (3) | C4···C5iv | 3.467 (4) |
O1···C2vi | 3.569 (3) | C4···C4iv | 3.541 (5) |
O2···C5vii | 3.390 (2) | | |
| | | |
Cl1—Cu1—O2 | 169.82 (6) | C2—C1—C5 | 118.0 (2) |
Cl1—Cu1—O3 | 93.45 (4) | O3—C2—C1 | 116.5 (2) |
Cl1—Cu1—O4W | 94.13 (5) | O3—C2—C3 | 124.1 (2) |
Cu1—Cl1—Cu1i | 124.04 (3) | C1—C2—C3 | 119.3 (2) |
Cl1x—Cu1—Cl1 | 101.38 (2) | O1—C3—C2 | 120.3 (2) |
O2—Cu1—Cl1x | 88.72 (6) | O1—C3—C6 | 112.6 (2) |
O2—Cu1—O3 | 84.84 (5) | C2—C3—C6 | 127.1 (2) |
O2—Cu1—O4W | 86.49 (6) | O1—C4—C5 | 122.8 (2) |
O3—Cu1—Cl1x | 91.98 (5) | O1—C4—H4 | 118.6 |
O3—Cu1—O4W | 169.75 (6) | C5—C4—H4 | 118.6 |
C3—O1—C4 | 120.6 (2) | C1—C5—C4 | 118.9 (2) |
Cu1—O2—C1 | 110.9 (1) | C1—C5—H5 | 120.5 |
Cu1—O3—C2 | 109.4 (1) | C4—C5—H5 | 120.5 |
Cu1—O4W—H4WA | 118 (2) | C3—C6—H6A | 109.5 |
Cu1—O4W—H4WB | 116.2 (19) | C3—C6—H6B | 109.5 |
H4WA—O4W—H4WB | 102 (3) | C3—C6—H6C | 109.5 |
H5WA—O5W—H5WB | 107 (3) | H6A—C6—H6B | 109.5 |
O2—C1—C2 | 118.0 (2) | H6A—C6—H6C | 109.5 |
O2—C1—C5 | 124.0 (2) | H6B—C6—H6C | 109.5 |
| | | |
Cl1—Cu1—O2—C1 | 85.9 (3) | O3—Cu1—O2—C1 | 5.2 (2) |
Cl1—Cu1—O3—C2 | −174.6 (1) | O3—C2—C1—C5 | −179.4 (2) |
Cu1—O2—C1—C2 | −4.6 (3) | O3—C2—C3—C6 | 0.2 (4) |
Cu1—O2—C1—C5 | 175.5 (2) | O4W—Cu1—O2—C1 | 179.7 (2) |
Cu1—O3—C2—C1 | 3.5 (2) | O4W—Cu1—O3—C2 | −36.9 (5) |
Cu1—O3—C2—C3 | −177.1 (2) | C1—C2—C3—C6 | 179.6 (2) |
O1—C3—C2—O3 | −179.4 (2) | C2—C1—C5—C4 | −1.1 (4) |
O1—C3—C2—C1 | 0.0 (3) | C2—C3—O1—C4 | −1.3 (3) |
O1—C4—C5—C1 | −0.2 (4) | C3—O1—C4—C5 | 1.4 (4) |
O2—Cu1—O3—C2 | −4.6 (1) | C3—C2—C1—C5 | 1.2 (3) |
O2—C1—C2—O3 | 0.8 (3) | C4—O1—C3—C6 | 179.1 (2) |
O2—C1—C2—C3 | −178.7 (2) | C4—O1—C3—C6 | 179.1 (2) |
O2—C1—C5—C4 | 178.7 (2) | | |
Symmetry codes: (i) x−1/2, −y+1/2, z; (ii) x−1, y, z−1; (iii) x+1/2, −y+1/2, z+1; (iv) −x+1, −y, −z+1; (v) −x, −y, −z; (vi) −x, −y, −z+1; (vii) −x+1, −y, −z+2; (viii) x−1/2, −y+1/2, z−1; (ix) x, y, z+1; (x) x+1/2, −y+1/2, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4W—H4WA···O5Wi | 0.79 (3) | 1.94 (2) | 2.711 (2) | 168 (3) |
O4W—H4WB···O5W | 0.80 (2) | 1.94 (2) | 2.706 (2) | 162 (2) |
O5W—H5WA···O3iii | 0.77 (3) | 2.16 (2) | 2.910 (2) | 164 (3) |
O5W—H5WB···O3xi | 0.79 (2) | 1.98 (2) | 2.768 (2) | 172 (3) |
Symmetry codes: (i) x−1/2, −y+1/2, z; (iii) x+1/2, −y+1/2, z+1; (xi) x+1, y, z+1. |
Experimental details
Crystal data |
Chemical formula | [Cu(C6H5O3)Cl(H2O)]·H2O |
Mr | 260.13 |
Crystal system, space group | Monoclinic, P21/a |
Temperature (K) | 296 |
a, b, c (Å) | 7.163 (2), 18.604 (2), 7.357 (2) |
β (°) | 113.38 (2) |
V (Å3) | 899.9 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.71 |
Crystal size (mm) | 0.40 × 0.20 × 0.10 |
|
Data collection |
Diffractometer | Rigaku AFC-5R diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.527, 0.763 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2302, 2069, 1778 |
Rint | 0.009 |
(sin θ/λ)max (Å−1) | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.021, 0.058, 1.07 |
No. of reflections | 2069 |
No. of parameters | 132 |
No. of restraints | ? |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.34, −0.28 |
Selected geometric parameters (Å, º) topCl1—Cu1 | 2.2445 (6) | Cu1—O4W | 1.965 (1) |
Cl1—Cu1i | 2.7546 (9) | O2—C1 | 1.272 (2) |
Cu1—O2 | 1.957 (1) | O3—C2 | 1.339 (2) |
Cu1—O3 | 1.947 (1) | | |
| | | |
Cl1—Cu1—O2 | 169.82 (6) | O2—Cu1—O4W | 86.49 (6) |
Cl1—Cu1—O3 | 93.45 (4) | O3—Cu1—Cl1ii | 91.98 (5) |
Cl1—Cu1—O4W | 94.13 (5) | O3—Cu1—O4W | 169.75 (6) |
Cu1—Cl1—Cu1i | 124.04 (3) | Cu1—O2—C1 | 110.9 (1) |
Cl1ii—Cu1—Cl1 | 101.38 (2) | Cu1—O3—C2 | 109.4 (1) |
O2—Cu1—Cl1ii | 88.72 (6) | O2—C1—C2 | 118.0 (2) |
O2—Cu1—O3 | 84.84 (5) | O3—C2—C1 | 116.5 (2) |
Symmetry codes: (i) x−1/2, −y+1/2, z; (ii) x+1/2, −y+1/2, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4W—H4WA···O5Wi | 0.79 (3) | 1.94 (2) | 2.711 (2) | 168 (3) |
O4W—H4WB···O5W | 0.80 (2) | 1.94 (2) | 2.706 (2) | 162 (2) |
O5W—H5WA···O3iii | 0.77 (3) | 2.16 (2) | 2.910 (2) | 164 (3) |
O5W—H5WB···O3iv | 0.79 (2) | 1.98 (2) | 2.768 (2) | 172 (3) |
Symmetry codes: (i) x−1/2, −y+1/2, z; (iii) x+1/2, −y+1/2, z+1; (iv) x+1, y, z+1. |
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Maltol (3-hydroxy-2-methyl-4H-pyran-4-one, (I), is a naturally occurring non-toxic compound. This compound has the ability to be deprotonated readily (pKa = 8.38; Hedlund & Öhman, 1988) and can act as an anionic chelating O,O'-bidentate ligand towards a number of biologically active metal ions. The metal complexes of (I) can be solubilized in water, and many biological studies have been reported employing this compound as a ligand. For instance, the AlIII complex has been studied in relation to apoptosis (Tsubouchi et al., 2001) and Alzheimer's disease (Finnegan et al., 1986), the FeIII complex has been used in the treatment of iron deficiency anaemia (Harvey et al., 1998), and the VIV complex is a potent insulin mimic (Caravan et al., 1995). The efficacy of the CuII and SnII complexes in oral care formations (Creeth et al., 2000) has also been reported. A number of crystal structures of maltolate–metal complexes have been reported, viz. AlIII (Finnegan et al., 1986; Yu et al., 2002), VIV (Caravan et al., 1995; Sun et al., 1996, 1998), FeIII (Ahmet et al., 1988), ZnII (Ahmed et al., 2000), MoIV (Lord et al., 1999), RuIV (Fryzuk et al., 1997), SnII (Barret et al., 2001) and SnIV (Denekamp et al., 1992; Bhattacharya et al., 1994). In this study, to obtain further evidence for the chelating mode of maltol with divalent metal ions, we have analyzed the crystal structure of the maltolate–CuII complex, (II).
The crystal structure of (II) is shown in Fig. 1. In this compound, the Cu atom is surrounded by five atoms in a square-pyramidal coordination geometry (Fig. 1), in which the basal plane is made up of two O atoms of the maltolate ligand, one Cl atom and one water O atom, and the Cl atom of the next complex occupies the apical position. The Cu atom is shifted about 0.15 Å from the average basal plane toward the apical Cl atom. The deprotonated hydroxyl and ketone O atoms of the ligand form a five-membered chelate ring with the Cu atom. The ketone C1—O2 bond length [1.272 (2) Å] is longer than that of free maltol [1.244 (3)–1.254 (3) Å; Burgess et al., 1996], and is shorter than the enol bond length [C2—O3 = 1.339 (2) Å] (Table 1). This indicates a distinction between Lewis acid–base interactions for the two types of O atoms. The Cl atom coordinates from the apical position more weakly to the tetracoordinate basal plane around the Cu atom, forming a square-pyramidal geometry, then the complexes related by the a glide form polymeric chain [Cl1—Cu1 = 2.2445 (6) Å, Cl1—Cu1i = 2.7546 (9) Å, Cu1—Cl1—Cu1i = 124.04 (3)° and Cl1—Cu1i—Cl1i 101.38 (2)°; symmetry code: (i) -1/2 + x, 1/2 - y, z] (Fig. 1). The two different Cu—Cl distances in the title compound are similar to those in the 5-formyluracil thioosemicarbazone–CuII complex [apical Cu—Cl = 2.665 (3) Å and basal Cu—Cl = 2.260 (3) Å], and the longer appical Cu—Cl bond is due to a Jahn–Teller effect (Ferrari et al., 1998). The polymeric chain and the analogous coordination sphere were observed in the crystal structure of catena-poly[bis(2-aminopyrimidine)aquacopper(II)-µ2-sulfato dihydrate] (Lumme et al., 1996).
In the crystal structure of (II), there are O—H···O hydrogen-bond interactions between solvate water molecules and the deprotonated O atoms of the maltolate ligands, and between solvate water and the copper-coordinated water molecules (Table 2). Also, stacking interactions exist between neighboring pyran rings [O1···C1ii 3.493 (3) Å, C2···C4ii 3.506 (3) Å and C3···C5ii 3.515 (4) Å; symmetry code: (ii) -x, -y, 1 - z].
The title compound is composed of maltolate and metal in a 1:1 ratio. This is the first observation of a 1:1 metal complex of maltol, although 2:1 and 3:1 maltolate–metal complexes, with ZnII (2:1), SnII (2:1), FeIII (3:1) and AlIII (3:1), have been reported. In all the metal complexes of maltol reported, the bidentate maltolate ligand forms a five-membered chelate ring.