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In the title compound, [Zr(C6H4NO2)4]·2H2O, the ZrIV atom is located on a crystallographic fourfold rotoinversion axis (\overline{4}) and is coordinated by four picolinate anions with Zr—O and Zr—N distances of 2.120 (2) and 2.393 (2) Å, respectively. An approximate square-anti­prismatic coordination polyhedron of the N,O-coordination ligand atoms is formed, with a distortion towards dodeca­hedral geometry. The crystal packing is stabilized by inter­molecular π–π inter­actions between adjacent picolinate rings [centroid–centroid distances = 3.271 (1) and 3.640 (2) Å], as well as O—H...O hydrogen bonds between the solvent mol­ecules and the coordinated ligands, thereby linking the mol­ecules into a supra­molecular three-dimensional network.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536811031710/zq2119sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536811031710/zq2119Isup2.hkl
Contains datablock I

CCDC reference: 845236

Key indicators

  • Single-crystal X-ray study
  • T = 100 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.037
  • wR factor = 0.100
  • Data-to-parameter ratio = 17.0

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT230_ALERT_2_C Hirshfeld Test Diff for O1 -- C1 .. 6.4 su PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L= 0.600 4 PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L= 0.600 5
Alert level G PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite 2 PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF .... ? PLAT152_ALERT_1_G The Supplied and Calc. Volume s.u. Differ by ... 2 Units PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels .......... 2 PLAT794_ALERT_5_G Note: Tentative Bond Valency for Zr1 (IV) 4.24 PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 1
0 ALERT level A = Most likely a serious problem - resolve or explain 0 ALERT level B = A potentially serious problem, consider carefully 3 ALERT level C = Check. Ensure it is not caused by an omission or oversight 6 ALERT level G = General information/check it is not something unexpected 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 2 ALERT type 5 Informative message, check

Comment top

The introduction of N,O-bidentate ligands with the oxine or aminovinylketone backbones significantly influences both steric and electronic properties of transition metal centres as illustrated by literature examples (Graham et al., 1991; Mtshali et al., 2006; Roodt et al., 2011; Schutte et al., 2008; Steyn et al., 1997; Van Aswegen et al., 1991; Van der Westhuizen et al., 2010). This study is part of ongoing research initiatives investigating coordination behaviour of O,O'- and N, O,-bidentate ligands with zirconium(IV) and hafnium(IV) for possible separation of these two metals from base ore sources (Steyn et al., 2008; Viljoen et al., 2010a,b).

The title compound, [Zr(C6H4NO2)4].2H2O, with C6H4NO2 as picolinic acid, crystallizes in the form of colourless cubic crystals in the tetragonal P42/n space group. The ZrIV atom, located on a crystallographic fourfold rotoinversion axis (4), is coordinated to four picolinic acid ligands (Fig. 1). The assymetric unit contains half a solvent molecule located on a twofold axis. The Zr—O and Zr—N bond lengths are 2.120 (2) Å and 2.393 (2) Å, respectively, with a N—Zr—O bite angle of 69.79 (7) °. The coordination polyhedron around the metal centre is an approximate square antiprism of the N,O-coordination ligand atoms, with a distortion towards dodecahedral geometry. The crystal packing is stabilized by intermolecular π-π interactions (Fig. 2), between adjacent picolinato rings, with interplanar and centroid-to-centroid distances of 3.271 (1) Å and 3.640 (2) Å, respectively. Further stabilization of the crystal structure is afforded by O—H···O hydrogen bonding (Fig. 3) between the carbonyl group of the picolinato ligands and the solvent water molecules. All of these interactions serve to link the molecules into a supramolecular three-dimensional network.

Related literature top

For N,O- and O,O'-bidentate ligand complexes of zirconium and hafnium, see: Steyn et al. (2008); Viljoen et al. (2010a,b). For relevant studies of N,O- and O,O'-bidentate ligands with other transition metal atoms, see: Graham et al. (1991); Mtshali et al. (2006); Roodt et al. (2011); Schutte et al. (2008); Steyn et al. (1997); Van Aswegen et al. (1991); Van der Westhuizen et al. (2010).

Experimental top

Chemicals were purchased from Sigma-Aldrich and used as received. ZrCl4 (103.3 mg, 0.463 mmol) and picolinic acid (PicA) (175.2 mg, 1.423 mmol) was separately dissolved in DMF (2.5 ml ea) and heated to 60 °C. The PicA solution was added drop-wise to the zirconium solution and stirred at 60 °C for 30 minutes. The reaction solution was removed from heating, covered and left to stand for crystallization. White cubic crystals, suitable for single-crystal X-ray diffraction, formed after 30 days (yield: 178 mg, 86%).

Refinement top

The aromatic H atoms were placed in geometrically idealized positions (C–H = 0.95 Å) and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C). The hydrogen atoms of the solvent water molecule were located on the Fourier difference map and refined isotropically. The highest residual electron density was located 0.74 Å from O1.

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. Representation of the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.
[Figure 2] Fig. 2. Graphical illustration of ππ interaction and stacking between different PicA-ligands of neighboring molecules to form a three-dimensional network (displacement ellipsoids are drawn at the 50% probability level). Hydrogen atoms and solvent water molecules omitted for clarity.
[Figure 3] Fig. 3. Graphical illustration of Zr(PicA)4 indicating O–H···O hydrogen bonding interaction as observed between the solvent molecules and the free carbonyl oxygen atoms from neighboring molecules (displacement ellipsoids are drawn at the 50% probability level).
Tetrakis(picolinato-κ2N,O)zirconium(IV) dihydrate top
Crystal data top
[Zr(C6H4NO2)4]·2H2ODx = 1.743 Mg m3
Mr = 615.66Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P42/nCell parameters from 9933 reflections
Hall symbol: -P 4bcθ = 2.6–28.4°
a = 11.083 (5) ŵ = 0.54 mm1
c = 9.548 (5) ÅT = 100 K
V = 1172.8 (10) Å3Cuboid, colourless
Z = 20.12 × 0.09 × 0.04 mm
F(000) = 624
Data collection top
Bruker X8 APEXII 4K Kappa CCD
diffractometer
1477 independent reflections
Radiation source: fine-focus sealed tube1271 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.074
ω and ϕ scansθmax = 28.5°, θmin = 2.6°
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
h = 1413
Tmin = 0.942, Tmax = 0.977k = 1414
27234 measured reflectionsl = 1212
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)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.10 w = 1/[σ2(Fo2) + (0.0415P)2 + 2.5407P]
where P = (Fo2 + 2Fc2)/3
1477 reflections(Δ/σ)max < 0.001
87 parametersΔρmax = 0.64 e Å3
1 restraintΔρmin = 0.92 e Å3
Crystal data top
[Zr(C6H4NO2)4]·2H2OZ = 2
Mr = 615.66Mo Kα radiation
Tetragonal, P42/nµ = 0.54 mm1
a = 11.083 (5) ÅT = 100 K
c = 9.548 (5) Å0.12 × 0.09 × 0.04 mm
V = 1172.8 (10) Å3
Data collection top
Bruker X8 APEXII 4K Kappa CCD
diffractometer
1477 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
1271 reflections with I > 2σ(I)
Tmin = 0.942, Tmax = 0.977Rint = 0.074
27234 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0371 restraint
wR(F2) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.10Δρmax = 0.64 e Å3
1477 reflectionsΔρmin = 0.92 e Å3
87 parameters
Special details top

Experimental. The intensity data were collected on a Bruker X8 ApexII 4 K Kappa CCD diffractometer using an exposure time of 40 s/frame. A total of 1709 frames were collected with a frame width of 0.5° covering up to θ = 28.40° with 99.5% completeness accomplished.

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
Zr10.250.250.750.01305 (15)
O10.41797 (14)0.31522 (14)0.82454 (18)0.01305 (15)
O20.56146 (18)0.33223 (18)0.9859 (2)0.0263 (4)
C30.4700 (2)0.1154 (2)1.1212 (3)0.0195 (5)
H30.54150.1441.16010.023*
N10.31289 (18)0.13671 (18)0.9505 (2)0.0157 (4)
C20.4174 (2)0.1737 (2)1.0089 (3)0.0169 (5)
C50.3088 (2)0.0267 (2)1.1131 (3)0.0206 (5)
H50.27070.09591.14610.025*
C60.2603 (2)0.0372 (2)1.0016 (3)0.0178 (5)
H60.18910.010.9610.021*
C40.4143 (2)0.0137 (2)1.1748 (3)0.0222 (5)
H40.44730.02691.2510.027*
C10.4728 (2)0.2822 (2)0.9379 (3)0.0183 (5)
O030.250.750.3385 (4)0.0472 (9)
H03A0.274 (4)0.815 (3)0.396 (4)0.068 (15)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zr10.01054 (17)0.01054 (17)0.0181 (2)000
O10.01054 (17)0.01054 (17)0.0181 (2)000
O20.0201 (9)0.0257 (10)0.0332 (11)0.0070 (8)0.0066 (8)0.0008 (8)
C30.0170 (11)0.0211 (12)0.0205 (12)0.0015 (9)0.0014 (9)0.0035 (10)
N10.0141 (9)0.0136 (9)0.0194 (10)0.0005 (8)0.0000 (8)0.0002 (8)
C20.0145 (11)0.0160 (11)0.0203 (12)0.0000 (9)0.0007 (9)0.0030 (9)
C50.0221 (12)0.0178 (12)0.0220 (13)0.0026 (9)0.0043 (10)0.0027 (10)
C60.0158 (11)0.0154 (11)0.0223 (12)0.0003 (9)0.0005 (9)0.0003 (9)
C40.0236 (13)0.0240 (13)0.0191 (13)0.0056 (10)0.0003 (10)0.0020 (10)
C10.0148 (11)0.0171 (11)0.0231 (12)0.0001 (9)0.0006 (9)0.0032 (9)
O030.059 (2)0.038 (2)0.045 (2)0.0011 (18)00
Geometric parameters (Å, º) top
Zr1—O1i2.1200 (18)C3—C41.384 (4)
Zr1—O12.1200 (18)C3—H30.93
Zr1—O1ii2.1200 (18)N1—C61.340 (3)
Zr1—O1iii2.1200 (18)N1—C21.349 (3)
Zr1—N1i2.393 (2)C2—C11.511 (4)
Zr1—N1ii2.393 (2)C5—C41.384 (4)
Zr1—N1iii2.393 (2)C5—C61.386 (4)
Zr1—N12.393 (2)C5—H50.93
O1—C11.294 (3)C6—H60.93
O2—C11.218 (3)C4—H40.93
C3—C21.381 (4)O03—H03A0.941 (19)
O1i—Zr1—O196.47 (3)N1i—Zr1—N1129.78 (7)
O1i—Zr1—O1ii96.47 (3)N1ii—Zr1—N173.76 (11)
O1—Zr1—O1ii140.77 (10)N1iii—Zr1—N1129.78 (7)
O1i—Zr1—O1iii140.77 (10)C1—O1—Zr1126.61 (15)
O1—Zr1—O1iii96.47 (3)C2—C3—C4118.7 (2)
O1ii—Zr1—O1iii96.47 (3)C2—C3—H3120.7
O1i—Zr1—N1i69.79 (7)C4—C3—H3120.7
O1—Zr1—N1i145.95 (7)C6—N1—C2118.2 (2)
O1ii—Zr1—N1i73.05 (7)C6—N1—Zr1126.65 (17)
O1iii—Zr1—N1i78.95 (7)C2—N1—Zr1114.94 (16)
O1i—Zr1—N1ii145.95 (7)N1—C2—C3122.8 (2)
O1—Zr1—N1ii78.95 (7)N1—C2—C1113.9 (2)
O1ii—Zr1—N1ii69.79 (7)C3—C2—C1123.3 (2)
O1iii—Zr1—N1ii73.05 (7)C4—C5—C6119.3 (2)
N1i—Zr1—N1ii129.78 (7)C4—C5—H5120.4
O1i—Zr1—N1iii78.95 (7)C6—C5—H5120.4
O1—Zr1—N1iii73.05 (7)N1—C6—C5122.1 (2)
O1ii—Zr1—N1iii145.95 (7)N1—C6—H6118.9
O1iii—Zr1—N1iii69.79 (7)C5—C6—H6118.9
N1i—Zr1—N1iii73.76 (11)C3—C4—C5118.9 (2)
N1ii—Zr1—N1iii129.78 (7)C3—C4—H4120.6
O1i—Zr1—N173.05 (7)C5—C4—H4120.6
O1—Zr1—N169.79 (7)O2—C1—O1124.4 (2)
O1ii—Zr1—N178.95 (7)O2—C1—C2121.4 (2)
O1iii—Zr1—N1145.95 (7)O1—C1—C2114.2 (2)
Symmetry codes: (i) y, x+1/2, z+3/2; (ii) x+1/2, y+1/2, z; (iii) y+1/2, x, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O03—H03A···O2iv0.94 (2)1.89 (2)2.829 (3)175 (5)
Symmetry code: (iv) y, x+3/2, z+3/2.

Experimental details

Crystal data
Chemical formula[Zr(C6H4NO2)4]·2H2O
Mr615.66
Crystal system, space groupTetragonal, P42/n
Temperature (K)100
a, c (Å)11.083 (5), 9.548 (5)
V3)1172.8 (10)
Z2
Radiation typeMo Kα
µ (mm1)0.54
Crystal size (mm)0.12 × 0.09 × 0.04
Data collection
DiffractometerBruker X8 APEXII 4K Kappa CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2004)
Tmin, Tmax0.942, 0.977
No. of measured, independent and
observed [I > 2σ(I)] reflections
27234, 1477, 1271
Rint0.074
(sin θ/λ)max1)0.671
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.100, 1.10
No. of reflections1477
No. of parameters87
No. of restraints1
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.64, 0.92

Computer programs: APEX2 (Bruker, 2010), SAINT-Plus (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O03—H03A···O2i0.941 (19)1.89 (2)2.829 (3)175 (5)
Symmetry code: (i) y, x+3/2, z+3/2.
 

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