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The crystal structure of the title compound, [Zn(C9H6NO)2(H2O)2], has been redetermined with better R factors (R1 = 0.0471) and higher accuracy than in previous publications. The molecule is centrosymmetric.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803018427/cv6213sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803018427/cv6213Isup2.hkl
Contains datablock I

CCDC reference: 222830

Key indicators

  • Single-crystal X-ray study
  • T = 294 K
  • Mean [sigma](C-C) = 0.004 Å
  • R factor = 0.042
  • wR factor = 0.117
  • Data-to-parameter ratio = 15.8

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X) Zn1 - O2 = 7.61 su
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 1 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

8-Quinolinol has been widely used in the quantitative analysis of W and Mo (Marcel & Rene, 1950). The complexes of 8-quinolinol with Nb, Mo, W and Hf emit interesting fluorescence (Schneider & Roselli, 1970). The crystal structure of the title compound, (I), was orginally determined by Merrit et al. (1954) with R1 = 0.226, and was then refined by Palenik (1964) to R1 = 0.13. Here, we present the results of a redetermination of the structure of (I) with better R factors (R1 = 0.0471) and higher accuracy.

In (I), the ZnII atom is six-coordinated, by one N and one O atom from each of the two 8-quinolinolate ligands and one O atom from each of the two aqua ligands. This ZnO4N2 coordination forms an octahedral geometry (Fig. 1). The chelate ligands are connected to the central atom through a Zn—O [1.965 (18) Å] single bond and a Zn—N [2.011 (2) Å] coordinative bond, with a bite angle of 83.88 (8)°, and they occupy the equatorial plane. The two aqua ligands occupy the apical positions of the octahedron, with a Zn—O bond length very close to that of W—O [1.968 (4) Å], but shorter than that of W—N [2.336 (4) Å], in dioxobis(8-quinolinolato-N, O)tungsten (VI) (Raj et al., 1999).

The bond angles in the aromatic ring system of (I) are found to be between 118.2 (5) and 121.7 (5)°. In the 8-quinolinolate ligands, the absence of any unusually long bonds and the marginally longer carbonyl bond [1.355 (6) Å versus 1.28 Å], shorter than the normal single bond in ether and alcohols (>1.4 Å), suggest that the delocalization extends over the entire molecule and will therefore withdraw more negative charge from the cation (Barton et al., 1983).

The coordinated water molecules of (I) interact with the O atom of the 8-quinolinolato ligands via intermolecuar hydrogen bonds (Table 1). These hydrogen bonds interconnect the molecules into chains along the c direction (Fig.2).

Experimental top

An ethanolic solution of 8-quinolinol (2 mmol in 20 ml of ethanol) was mixed with Zn(OAc)2 (1 mmol in 20 ml of H2O). The resulting solution was left to stand for 5 h and a pale-yellowish solid was obtained. The product was recrystallized from ethanol-water (Ratio?). After several days, pale-yellowish crystals of (I) were harvested. Analysis, found: C 55.41, H 4.23, N 7.42%; calculated: C 55.52, H 4.14, N 7.47%.

Refinement top

The H atoms of the water ligands were located in a difference Fourier map and refined with a common isotropic displacement parameter. O—H and H···H distances were restrained to ensure a reasonable geometry for the water molecules. H atoms bound to C atoms were fixed geometrically and were treated as riding on the parent C atoms, with C—H = 0.93 Å and Uiso(H) = 1.2–1.5Ueq(C).

Computing details top

Data collection: SMART (Bruker, 1996); cell refinement: SMART; data reduction: SHELXTL (Bruker, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. A view of the molecule of (I) with the atom-numbering scheme and with 30% probability displacement ellipsoids.
[Figure 2] Fig. 2. Packing view of (I).
Diaquabis(8-quinolinolato-κ2N,O)zinc(II) top
Crystal data top
C18H16N2O4ZnF(000) = 400
Mr = 389.70Dx = 1.643 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -p 2ybcCell parameters from 2881 reflections
a = 12.955 (2) Åθ = 1–27.5°
b = 5.5463 (10) ŵ = 1.59 mm1
c = 11.423 (2) ÅT = 294 K
β = 106.288 (4)°Plate, yellow
V = 787.8 (2) Å30.30 × 0.24 × 0.12 mm
Z = 2
Data collection top
Siemens SMART CCD area-detector
diffractometer
1820 independent reflections
Radiation source: fine-focus sealed tube1382 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
ϕ and ω scansθmax = 27.6°, θmin = 3.3°
Absorption correction: multi-scan
(SADABS; Sheldrick 1996)
h = 1516
Tmin = 0.648, Tmax = 0.833k = 57
5060 measured reflectionsl = 1414
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.117H atoms treated by a mixture of independent and constrained refinement
S = 1.02 w = 1/[σ2(Fo2) + (0.0725P)2]
where P = (Fo2 + 2Fc2)/3
1820 reflections(Δ/σ)max < 0.001
115 parametersΔρmax = 0.60 e Å3
0 restraintsΔρmin = 0.37 e Å3
Crystal data top
C18H16N2O4ZnV = 787.8 (2) Å3
Mr = 389.70Z = 2
Monoclinic, P21/cMo Kα radiation
a = 12.955 (2) ŵ = 1.59 mm1
b = 5.5463 (10) ÅT = 294 K
c = 11.423 (2) Å0.30 × 0.24 × 0.12 mm
β = 106.288 (4)°
Data collection top
Siemens SMART CCD area-detector
diffractometer
1820 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick 1996)
1382 reflections with I > 2σ(I)
Tmin = 0.648, Tmax = 0.833Rint = 0.035
5060 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.117H atoms treated by a mixture of independent and constrained refinement
S = 1.02Δρmax = 0.60 e Å3
1820 reflectionsΔρmin = 0.37 e Å3
115 parameters
Special details top

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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Zn10.50000.50000.50000.02949 (18)
O20.50256 (19)0.2156 (4)0.33660 (19)0.0455 (6)
H2A0.51720.07170.36130.055*
H2B0.49010.21730.25950.055*
O10.56840 (15)0.7428 (3)0.42094 (17)0.0301 (4)
N10.65223 (18)0.3964 (4)0.57992 (19)0.0282 (5)
C10.7222 (2)0.5406 (5)0.5430 (2)0.0276 (6)
C20.6746 (2)0.7249 (5)0.4561 (2)0.0277 (6)
C30.7427 (2)0.8711 (6)0.4150 (3)0.0389 (7)
H30.71430.99070.35810.047*
C40.8539 (2)0.8422 (6)0.4576 (3)0.0446 (8)
H40.89800.94400.42810.053*
C50.9005 (2)0.6691 (6)0.5412 (3)0.0403 (7)
H50.97500.65600.56900.048*
C60.8349 (2)0.5114 (5)0.5847 (3)0.0327 (6)
C70.8730 (2)0.3211 (6)0.6687 (3)0.0406 (7)
H70.94650.29490.70000.049*
C80.8020 (3)0.1775 (6)0.7034 (3)0.0423 (8)
H80.82660.05200.75810.051*
C90.6913 (2)0.2195 (5)0.6561 (3)0.0345 (6)
H90.64360.11810.67970.041*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.0244 (3)0.0300 (3)0.0321 (3)0.00157 (17)0.00474 (19)0.00763 (18)
O20.0730 (17)0.0278 (11)0.0322 (11)0.0081 (10)0.0088 (11)0.0004 (9)
O10.0266 (10)0.0295 (10)0.0319 (10)0.0020 (8)0.0045 (8)0.0088 (8)
N10.0283 (12)0.0292 (12)0.0250 (11)0.0025 (10)0.0039 (10)0.0010 (10)
C10.0249 (14)0.0305 (15)0.0255 (13)0.0013 (10)0.0038 (11)0.0038 (10)
C20.0281 (14)0.0283 (14)0.0253 (13)0.0016 (11)0.0051 (11)0.0019 (10)
C30.0364 (17)0.0416 (19)0.0374 (16)0.0044 (13)0.0083 (14)0.0068 (14)
C40.0362 (17)0.051 (2)0.0479 (19)0.0133 (14)0.0149 (15)0.0024 (15)
C50.0258 (15)0.0492 (19)0.0444 (18)0.0027 (13)0.0076 (13)0.0077 (14)
C60.0260 (14)0.0390 (17)0.0299 (15)0.0014 (12)0.0023 (12)0.0063 (12)
C70.0297 (16)0.0458 (18)0.0410 (17)0.0087 (13)0.0013 (13)0.0004 (14)
C80.0444 (19)0.0396 (17)0.0361 (16)0.0145 (14)0.0000 (14)0.0035 (13)
C90.0357 (16)0.0331 (16)0.0322 (15)0.0045 (12)0.0054 (13)0.0045 (12)
Geometric parameters (Å, º) top
Zn1—O11.9655 (18)C2—C31.375 (4)
Zn1—O1i1.9655 (18)C3—C41.394 (4)
Zn1—N1i2.011 (2)C3—H30.9300
Zn1—N12.011 (2)C4—C51.370 (5)
Zn1—O2i2.451 (2)C4—H40.9300
Zn1—O22.451 (2)C5—C61.404 (4)
O2—H2A0.8500C5—H50.9300
O2—H2B0.8501C6—C71.419 (4)
O1—C21.324 (3)C7—C81.357 (5)
N1—C91.315 (4)C7—H70.9300
N1—C11.362 (4)C8—C91.402 (4)
C1—C61.412 (4)C8—H80.9300
C1—C21.438 (4)C9—H90.9300
O1—Zn1—O1i180.0O1—C2—C3124.3 (3)
O1—Zn1—N1i96.12 (8)O1—C2—C1118.1 (2)
O1i—Zn1—N1i83.88 (8)C3—C2—C1117.6 (3)
O1—Zn1—N183.88 (8)C2—C3—C4120.9 (3)
O1i—Zn1—N196.12 (8)C2—C3—H3119.6
N1i—Zn1—N1180.0C4—C3—H3119.6
O1—Zn1—O2i90.75 (8)C5—C4—C3122.2 (3)
O1i—Zn1—O2i89.25 (7)C5—C4—H4118.9
N1i—Zn1—O2i86.60 (8)C3—C4—H4118.9
N1—Zn1—O2i93.40 (8)C4—C5—C6119.4 (3)
O1—Zn1—O289.25 (7)C4—C5—H5120.3
O1i—Zn1—O290.75 (8)C6—C5—H5120.3
N1i—Zn1—O293.40 (8)C5—C6—C1118.7 (3)
N1—Zn1—O286.60 (8)C5—C6—C7124.9 (3)
O2i—Zn1—O2180.0C1—C6—C7116.4 (3)
Zn1—O2—H2A113.6C8—C7—C6119.9 (3)
Zn1—O2—H2B138.0C8—C7—H7120.0
H2A—O2—H2B108.4C6—C7—H7120.0
C2—O1—Zn1111.90 (16)C7—C8—C9119.6 (3)
C9—N1—C1118.5 (2)C7—C8—H8120.2
C9—N1—Zn1131.3 (2)C9—C8—H8120.2
C1—N1—Zn1110.18 (17)N1—C9—C8122.8 (3)
N1—C1—C6122.9 (2)N1—C9—H9118.6
N1—C1—C2115.9 (2)C8—C9—H9118.6
C6—C1—C2121.2 (3)
N1i—Zn1—O1—C2179.56 (17)C6—C1—C2—O1179.9 (2)
N1—Zn1—O1—C20.44 (17)N1—C1—C2—C3178.8 (2)
O2i—Zn1—O1—C292.90 (17)C6—C1—C2—C30.2 (4)
O2—Zn1—O1—C287.10 (17)O1—C2—C3—C4179.3 (3)
O1—Zn1—N1—C9177.9 (3)C1—C2—C3—C40.8 (4)
O1i—Zn1—N1—C92.1 (3)C2—C3—C4—C50.1 (5)
O2i—Zn1—N1—C991.7 (3)C3—C4—C5—C61.1 (5)
O2—Zn1—N1—C988.3 (3)C4—C5—C6—C11.6 (4)
O1—Zn1—N1—C11.01 (18)C4—C5—C6—C7178.3 (3)
O1i—Zn1—N1—C1178.99 (18)N1—C1—C6—C5179.9 (3)
O2i—Zn1—N1—C189.38 (18)C2—C1—C6—C51.0 (4)
O2—Zn1—N1—C190.62 (18)N1—C1—C6—C70.0 (4)
C9—N1—C1—C61.3 (4)C2—C1—C6—C7178.9 (3)
Zn1—N1—C1—C6179.6 (2)C5—C6—C7—C8179.1 (3)
C9—N1—C1—C2177.7 (2)C1—C6—C7—C80.8 (4)
Zn1—N1—C1—C21.4 (3)C6—C7—C8—C90.3 (5)
Zn1—O1—C2—C3179.7 (2)C1—N1—C9—C81.8 (4)
Zn1—O1—C2—C10.2 (3)Zn1—N1—C9—C8179.3 (2)
N1—C1—C2—O11.1 (4)C7—C8—C9—N11.0 (5)
Symmetry code: (i) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2A···O1ii0.851.992.841 (3)174
O2—H2B···O1iii0.851.992.829 (3)169
Symmetry codes: (ii) x, y1, z; (iii) x+1, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC18H16N2O4Zn
Mr389.70
Crystal system, space groupMonoclinic, P21/c
Temperature (K)294
a, b, c (Å)12.955 (2), 5.5463 (10), 11.423 (2)
β (°) 106.288 (4)
V3)787.8 (2)
Z2
Radiation typeMo Kα
µ (mm1)1.59
Crystal size (mm)0.30 × 0.24 × 0.12
Data collection
DiffractometerSiemens SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick 1996)
Tmin, Tmax0.648, 0.833
No. of measured, independent and
observed [I > 2σ(I)] reflections
5060, 1820, 1382
Rint0.035
(sin θ/λ)max1)0.651
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.117, 1.02
No. of reflections1820
No. of parameters115
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.60, 0.37

Computer programs: SMART (Bruker, 1996), SMART, SHELXTL (Bruker, 1996), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL.

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2A···O1i0.851.992.841 (3)174
O2—H2B···O1ii0.851.992.829 (3)169
Symmetry codes: (i) x, y1, z; (ii) x+1, y1/2, z+1/2.
 

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