trans-Tetra­aqua­bis­­[2-(4-chloro­phen­­oxy)acetato-κO¹]nickel(II)

In the title compound, [Ni(C₈H₆ClO₃)₂(H₂O)₄], the Ni^II ion is located on a crystallographic inversion centre and is octa­hedrally coordinated by two 2-(4-chloro­phen­oxy)acetate ligands in axial positions and by four water mol­ecules in the equatorial plane. The acetate ligands are bound to the Ni^II ion in a monodentate manner through a carboxyl­ate O atom. In the crystal, O—H⋯O hydrogen bonds link the mol­ecules, forming a two-dimensional supra­molecular network lying parallel to the ab plane.

Related literature

For inter­actions of metal ions with amino acids, see: Daniele et al. (2008); Parkin (2004). For the crystal structures of related 4-chloro­phen­oxy­acetate complexes, see: Liwporncharoenvong & Luck (2005); Smith et al. (1980); Wang et al. (2008).

Experimental

Crystal data

• [Ni(C₈H₆ClO₃)₂(H₂O)₄]

• M_r = 501.93

• Triclinic,

• a = 4.894 (3) Å

• b = 5.769 (4) Å

• c = 18.369 (9) Å

• α = 97.226 (3)°

• β = 90.088 (4)°

• γ = 96.796 (4)°

• V = 510.8 (5) ų

• Z = 1

• Cu Kα radiation

• μ = 4.25 mm⁻¹

• T = 293 K

• 0.45 × 0.22 × 0.2 mm

Data collection

• Oxford Diffraction Xcalibur Ruby diffractometer

• Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) T_min = 0.226, T_max = 1.000

• 4607 measured reflections

• 2059 independent reflections

• 1759 reflections with I > 2σ(I)

• R_int = 0.052

Refinement

• R[F² > 2σ(F²)] = 0.099

• wR(F²) = 0.272

• S = 1.13

• 2059 reflections

• 135 parameters

• H-atom parameters constrained

• Δρ_max = 2.78 e Å⁻³

• Δρ_min = −1.32 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2W—H2WA⋯O3	0.87	1.93	2.679 (4)	144
O2W—H2WB⋯O1W^i	0.87	2.01	2.843 (4)	162
O1W—H1WA⋯O3^ii	0.86	1.98	2.732 (4)	145
O1W—H1WB⋯O1^iii	0.86	2.21	2.978 (4)	148
O1W—H1WB⋯O2^iii	0.86	2.18	2.861 (4)	135
Symmetry codes: (i) x-1, y, z; (ii) -x+2, -y, -z+1; (iii) -x+3, -y+1, -z+1.

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

The interaction of transition metal ions with biologically active molecules such as amino acids and various organic acids is very important in biological systems (Parkin, 2004; Daniele et al., 2008). 4-chlorophenoxyacetic acid is one such acid that has been used to form various complexes with transition metals (Liwporncharoenvong & Luck, 2005; Smith et al., 1980; Wang et al., 2008). We report herein on the synthesis and crystal structure of a new nickel(II) complex involving this ligand.

In the title compound the Ni^II ion is located on a crystallographic inversion centre (Fig. 1). The Ni^II ion is octahedral coordinated by two p-chlorophenoxyacetato ligands in axial positions [Ni—O = 2.060 (3) Å] and by four water molecules in the equatorial plane [Ni—O = 2.084 (3) and 2.039 (3) Å]. The p-chlorophenoxyacetato ligands are bound to the Ni^II ion in a monodentate manner through a carboxylate O atom.

In the crystal, molecules are linked via O-H···O hydrogen bonds (Table 1), resulting in the formation of a complex two-dimensional supramolecular network lying parallel to the ab plane (Fig. 2).

Related literature

For interactions of metal ions with amino acids, see: Daniele et al. (2008); Parkin (2004). For the crystal structures of related 4-chlorophenoxyacetate complexes, see: Liwporncharoenvong & Luck (2005); Smith et al. (1980); Wang et al. (2008).

S2. Experimental

A solution of 4-chlorophenoxyacetic acid (40 mg, 0.2 mmol) in ethanol (3 ml) was added to a solution of Ni(CH₃OO)₂ [15.96 mg 0.1 mmol] in water (1.5 ml) and stirred for 10 min at 303 K. Slow evaporation of the resulting solution gave green block-like crystals of the title compound suitable for X-ray analysis.

S3. Refinement

All the H atoms were included in calculated positions and treated as riding: C—H = 0.97 Å (methylene), 0.93 Å (aromatic) and O—H = 0.86 Å, with U_iso(H) = k × U_eq(parent atom), where k = 1.5 for water H atoms and = 1.2 for other H atoms. In the final difference Fourier map the highest residual density peak is located near the metal atom.

Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound with the atom-labeling scheme. Displacement ellipsoids are drawn at the 30% probability level [symmetry code: (a) -x+2, -y+1, -z+1].
	Fig. 2. A view along the a axis of the crystal packing of title compound. Hydrogen bonds are shown as dashed lines - see Table 1 for details.

trans-Tetraaquabis[2-(4-chlorophenoxy)acetato-κO¹]nickel(II)

Crystal data

[Ni(C8H6ClO3)2(H2O)4]	V = 510.8 (5) Å^3
Mr = 501.93	Z = 1
Triclinic, P1	F(000) = 258
Hall symbol: -P 1	Dx = 1.632 Mg m^−3
a = 4.894 (3) Å	Cu Kα radiation, λ = 1.54184 Å
b = 5.769 (4) Å	µ = 4.25 mm^−1
c = 18.369 (9) Å	T = 293 K
α = 97.226 (3)°	Block, green
β = 90.088 (4)°	0.45 × 0.22 × 0.2 mm
γ = 96.796 (4)°

Data collection

Oxford Diffraction Xcalibur Ruby diffractometer	2059 independent reflections
Radiation source: fine-focus sealed tube	1759 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.052
Detector resolution: 10.2576 pixels mm^-1	θmax = 75.9°, θmin = 4.9°
ω scans	h = −5→6
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	k = −7→6
Tmin = 0.226, Tmax = 1.000	l = −19→23
4607 measured reflections

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)] = 0.099	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.272	H-atom parameters constrained
S = 1.13	w = 1/[σ^2(Fo^2) + (0.2P)^2] where P = (Fo^2 + 2Fc^2)/3
2059 reflections	(Δ/σ)max = 0.002
135 parameters	Δρmax = 2.78 e Å^−3
0 restraints	Δρmin = −1.32 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Ni1	1.0000	0.5000	0.5000	0.0282 (4)
Cl1	2.2639 (4)	0.3457 (4)	0.04767 (9)	0.0837 (7)
O2W	0.7333 (6)	0.2008 (5)	0.50078 (16)	0.0359 (7)
H2WA	0.7214	0.1192	0.4577	0.054*
H2WB	0.5706	0.2354	0.5131	0.054*
O1	1.5117 (7)	0.3222 (6)	0.29609 (16)	0.0413 (8)
O1W	1.2630 (6)	0.3692 (5)	0.56991 (15)	0.0344 (7)
H1WA	1.1689	0.2886	0.5999	0.052*
H1WB	1.3660	0.4834	0.5951	0.052*
O3	0.9237 (6)	0.0301 (5)	0.37074 (15)	0.0379 (7)
O2	1.2116 (7)	0.3526 (5)	0.41255 (16)	0.0369 (7)
C1	1.6813 (9)	0.3129 (8)	0.2362 (2)	0.0383 (10)
C7	1.3174 (9)	0.1227 (7)	0.3018 (2)	0.0358 (9)
H7A	1.4128	−0.0122	0.3075	0.043*
H7B	1.2049	0.0863	0.2574	0.043*
C8	1.1359 (8)	0.1725 (6)	0.36740 (19)	0.0293 (8)
C2	1.8536 (13)	0.5167 (10)	0.2301 (3)	0.0539 (13)
H2	1.8489	0.6472	0.2651	0.065*
C6	1.6845 (11)	0.1169 (10)	0.1845 (3)	0.0491 (12)
H6	1.5671	−0.0199	0.1885	0.059*
C5	1.8678 (12)	0.1279 (12)	0.1261 (3)	0.0564 (13)
H5	1.8740	−0.0029	0.0912	0.068*
C4	2.0382 (12)	0.3318 (12)	0.1203 (3)	0.0556 (13)
C3	2.0336 (14)	0.5284 (12)	0.1721 (3)	0.0621 (15)
H3	2.1495	0.6659	0.1680	0.075*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0331 (6)	0.0178 (6)	0.0305 (6)	−0.0016 (4)	0.0044 (4)	−0.0044 (4)
Cl1	0.0815 (12)	0.1170 (16)	0.0516 (9)	0.0067 (10)	0.0316 (8)	0.0111 (9)
O2W	0.0349 (15)	0.0225 (14)	0.0465 (16)	−0.0025 (11)	0.0093 (12)	−0.0043 (11)
O1	0.0472 (18)	0.0345 (16)	0.0357 (15)	−0.0041 (13)	0.0120 (13)	−0.0122 (12)
O1W	0.0383 (16)	0.0235 (13)	0.0385 (14)	−0.0042 (11)	−0.0019 (11)	−0.0007 (10)
O3	0.0471 (18)	0.0272 (15)	0.0356 (14)	−0.0039 (12)	0.0041 (12)	−0.0025 (11)
O2	0.0440 (17)	0.0270 (15)	0.0350 (14)	−0.0025 (12)	0.0047 (12)	−0.0085 (11)
C1	0.040 (2)	0.041 (2)	0.0317 (18)	0.0007 (18)	0.0084 (16)	−0.0002 (16)
C7	0.040 (2)	0.028 (2)	0.0350 (19)	−0.0020 (16)	0.0032 (16)	−0.0069 (15)
C8	0.035 (2)	0.0217 (18)	0.0299 (17)	0.0043 (14)	−0.0009 (14)	−0.0035 (13)
C2	0.067 (4)	0.041 (3)	0.047 (3)	−0.008 (2)	0.014 (2)	−0.004 (2)
C6	0.057 (3)	0.046 (3)	0.039 (2)	0.000 (2)	0.010 (2)	−0.0071 (19)
C5	0.058 (3)	0.067 (4)	0.040 (2)	0.006 (3)	0.011 (2)	−0.010 (2)
C4	0.056 (3)	0.068 (4)	0.042 (2)	0.001 (3)	0.010 (2)	0.008 (2)
C3	0.068 (4)	0.060 (3)	0.055 (3)	−0.009 (3)	0.021 (3)	0.009 (3)

Geometric parameters (Å, º)

Ni1—O2W^i	2.039 (3)	O2—C8	1.263 (5)
Ni1—O2W	2.039 (3)	C1—C2	1.380 (7)
Ni1—O2	2.060 (3)	C1—C6	1.383 (7)
Ni1—O2^i	2.060 (3)	C7—C8	1.516 (5)
Ni1—O1W^i	2.084 (3)	C7—H7A	0.9700
Ni1—O1W	2.084 (3)	C7—H7B	0.9700
Cl1—C4	1.737 (5)	C2—C3	1.386 (7)
O2W—H2WA	0.8668	C2—H2	0.9300
O2W—H2WB	0.8667	C6—C5	1.403 (7)
O1—C1	1.379 (5)	C6—H6	0.9300
O1—C7	1.419 (5)	C5—C4	1.375 (9)
O1W—H1WA	0.8641	C5—H5	0.9300
O1W—H1WB	0.8642	C4—C3	1.388 (9)
O3—C8	1.252 (5)	C3—H3	0.9300
O2W^i—Ni1—O2W	180.0	C2—C1—C6	120.6 (4)
O2W^i—Ni1—O2	87.58 (12)	O1—C7—C8	109.7 (3)
O2W—Ni1—O2	92.42 (12)	O1—C7—H7A	109.7
O2W^i—Ni1—O2^i	92.42 (12)	C8—C7—H7A	109.7
O2W—Ni1—O2^i	87.58 (12)	O1—C7—H7B	109.7
O2—Ni1—O2^i	180.00 (11)	C8—C7—H7B	109.7
O2W^i—Ni1—O1W^i	89.06 (12)	H7A—C7—H7B	108.2
O2W—Ni1—O1W^i	90.94 (13)	O3—C8—O2	126.7 (4)
O2—Ni1—O1W^i	91.59 (13)	O3—C8—C7	116.0 (3)
O2^i—Ni1—O1W^i	88.41 (13)	O2—C8—C7	117.3 (4)
O2W^i—Ni1—O1W	90.95 (13)	C1—C2—C3	120.6 (5)
O2W—Ni1—O1W	89.05 (12)	C1—C2—H2	119.7
O2—Ni1—O1W	88.41 (13)	C3—C2—H2	119.7
O2^i—Ni1—O1W	91.59 (13)	C1—C6—C5	118.9 (5)
O1W^i—Ni1—O1W	180.00 (12)	C1—C6—H6	120.6
Ni1—O2W—H2WA	110.5	C5—C6—H6	120.6
Ni1—O2W—H2WB	110.4	C4—C5—C6	120.1 (5)
H2WA—O2W—H2WB	108.4	C4—C5—H5	120.0
C1—O1—C7	117.3 (3)	C6—C5—H5	120.0
Ni1—O1W—H1WA	110.3	C5—C4—C3	120.8 (5)
Ni1—O1W—H1WB	110.4	C5—C4—Cl1	120.1 (5)
H1WA—O1W—H1WB	108.6	C3—C4—Cl1	119.1 (4)
C8—O2—Ni1	128.6 (3)	C2—C3—C4	119.0 (5)
O1—C1—C2	115.3 (4)	C2—C3—H3	120.5
O1—C1—C6	124.0 (4)	C4—C3—H3	120.5

Symmetry code: (i) −x+2, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2W—H2WA···O3	0.87	1.93	2.679 (4)	144
O2W—H2WB···O1W^ii	0.87	2.01	2.843 (4)	162
O1W—H1WA···O3^iii	0.86	1.98	2.732 (4)	145
O1W—H1WB···O1^iv	0.86	2.21	2.978 (4)	148
O1W—H1WB···O2^iv	0.86	2.18	2.861 (4)	135

Symmetry codes: (ii) x−1, y, z; (iii) −x+2, −y, −z+1; (iv) −x+3, −y+1, −z+1.