(IUCr) Crystallography Journals Online

Abstract top

In the title complex, [Ni(C₂₀H₁₄N₂O₄)]·2H₂O, the Ni^II ion is in an essentially square-planar geometry involving an N₂O₂ atom set of the tetradentate Schiff base ligand. The Ni atom lies on a crystallographic twofold rotation axis. The asymmetric unit contains one half-molecule of the complex and a water molecule. An intermolecular O-HO hydrogen bond forms a four-membered ring, producing an R₁²(4) ring motif involving a bifurcated hydrogen bond to the phenolate O atoms of the complex molecule. In the crystal structure, molecules are linked by [pi] - [pi] stacking interactions, with centroid-centroid distances in the range 3.5750 (11)-3.7750 (11) Å. As a result of the twofold symmetry, the central benzene ring makes the same dihedral angle of 15.75 (9)° with the two outer benzene rings. The dihedral angle between the two hydroxyphenyl rings is 13.16 (5)°. In the crystal structure, molecules are linked into infinite one-dimensional chains by directed four-membered O-HO-H interactions along the c axis and are further connected by C-HO and [pi] - [pi] stacking into a three-dimensional network. An interesting feature of the crystal structure is the short NiO, OO and NN interactions which are shorter than the sum of the van der Waals radii of the relevant atoms. The crystal structure is stabilized by intermolecular O-HO and C-HO hydrogen bonds and by [pi] - [pi] stacking interactions.

Comment top

Schiff base complexes are some of the most important stereochemical models in transition metal coordination chemistry, with their ease of preparation and structural variations (Granovski et al., 1993). Many of the reported structural investigations of these complexes are discussed in some details in a review (Hodgson, 1975). Metal derivatives of Schiff bases have been studied extensively, and Cu(II) and Ni(II) complexes play a major role in both synthetic and structural research (Elmali et al., 2000; Blower, 1998; Fun & Kia, 2008a,b; Granovski et al., 1993; Li & Chang, 1991; Shahrokhian et al., 2000). Tetradentate Schiff base metal complexes may form trans or cis planar or tetrahedral structures (Elmali et al., 2000).

In the title compound (Fig. 1), the Ni^II ion, is in an essentially square-planar geometry involving a N₂O₂ atom set of the tetradentate Schiff base ligand. The Ni atom lies on a crystallographic twofold rotation axis. An intermolecular O—H···O hydrogen bond forms a four-membered ring, producing an R²₁(4) ring motif (Bernstein et al., 1995). The bond lengths are within the normal ranges (Allen et al., 1987). The asymmetric unit contains one-half of the molecule of the complex and a water molecule. The latter shows a bifurcated hydrogen bond which is connected to the phenolato oxygen atoms of the complex. The molecule is nearly planar, with a maximum deviation from the mean plane of 0.370 (2) Å for atom C9. As a result of the twofold symmetry, the central benzene ring makes the same dihedral angle of 15.75 (9)° with the two outer benzene rings. The dihedral angle between the two hydroxy phenyl rings is 13.16 (5)°. In the crystal structure, (Fig. 2) molecules are linked into infinite one-dimensional chains by directed four-membered O—H···O—H interactions along the c axis and are furthered connected by C—H···O and π-π stacking into a three-dimensional network.

An interesting feature of the crystal structure is the short Ni···O, O···O, and N···N interactions (Table 1), which are shorter than the sum of the van der Waals radii of the relevant atoms. The short distances between the centroids of the five- and six-membered rings indicate the existence of the π-π interactions (Table 1). The crystal structure is stabilized by intermolecular O—H···O, C—H···O hydrogen bonds (Table 2) and π-π interactions.

{5,5'-Dihydroxy-2,2'-[o-phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II) dihydrate top

Crystal data top

[Ni(C₂₀H₁₄N₂O₄)]·2H₂O	F₀₀₀ = 912
M_r = 441.07	D_x = 1.716 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 3113 reflections
a = 10.9049 (2) Å	θ = 2.3–29.1º
b = 17.6602 (3) Å	µ = 1.18 mm⁻¹
c = 9.0375 (3) Å	T = 100.0 (1) K
β = 101.150 (1)º	Block, red
V = 1707.61 (7) Å³	0.35 × 0.12 × 0.11 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3566 independent reflections
Radiation source: fine-focus sealed tube	2388 reflections with I > 2σ(I)
Monochromator: graphite	R_int = 0.046
T = 100.0(1) K	θ_max = 34.3º
φ and ω scans	θ_min = 2.2º
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −17→17
T_min = 0.683, T_max = 0.881	k = −23→27
14574 measured reflections	l = −14→14

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.048	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.121	w = 1/[σ²(F_o²) + (0.0492P)²] where P = (F_o² + 2F_c²)/3
S = 1.12	(Δ/σ)_max < 0.001
3566 reflections	Δρ_max = 0.61 e Å⁻³
136 parameters	Δρ_min = −0.73 e Å⁻³
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Crystal data top

[Ni(C₂₀H₁₄N₂O₄)]·2H₂O	V = 1707.61 (7) Å³
M_r = 441.07	Z = 4
Monoclinic, C2/c	Mo Kα
a = 10.9049 (2) Å	µ = 1.18 mm⁻¹
b = 17.6602 (3) Å	T = 100.0 (1) K
c = 9.0375 (3) Å	0.35 × 0.12 × 0.11 mm
β = 101.150 (1)º

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3566 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2388 reflections with I > 2σ(I)
T_min = 0.683, T_max = 0.881	R_int = 0.046
14574 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	136 parameters
wR(F²) = 0.121	H atoms treated by a mixture of independent and constrained refinement
S = 1.12	Δρ_max = 0.61 e Å⁻³
3566 reflections	Δρ_min = −0.73 e Å⁻³

Special details top

Experimental. The low-temperature data was collected with the Oxford Cryosystem Cobra low-temperature attachment
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Experimental. The low-temperature data was collected with the Oxford Cryosystem Cobra low-temperature attachment

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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

	x	y	z	U_iso*/U_eq
Ni1	0.0000	0.246535 (17)	0.7500	0.01493 (11)
O1	0.04391 (12)	0.32501 (7)	0.88434 (14)	0.0174 (3)
O2	0.18665 (13)	0.44913 (8)	1.35074 (15)	0.0215 (3)
N1	0.06039 (14)	0.17016 (8)	0.88409 (17)	0.0152 (3)
C1	0.09715 (16)	0.32009 (10)	1.0287 (2)	0.0159 (4)
C2	0.11546 (17)	0.38691 (10)	1.1132 (2)	0.0175 (4)
H2A	0.0908	0.4329	1.0668	0.021*
C3	0.16965 (17)	0.38546 (10)	1.2647 (2)	0.0161 (4)
C4	0.21006 (17)	0.31684 (11)	1.3364 (2)	0.0200 (4)
H4A	0.2474	0.3160	1.4380	0.024*
C5	0.1937 (2)	0.25113 (10)	1.2545 (2)	0.0192 (4)
H5A	0.2218	0.2058	1.3015	0.023*
C6	0.13518 (18)	0.25029 (10)	1.1002 (2)	0.0160 (3)
C7	0.11768 (17)	0.17979 (10)	1.0251 (2)	0.0172 (4)
H7A	0.1490	0.1369	1.0793	0.021*
C8	0.03852 (17)	0.09645 (10)	0.8211 (2)	0.0181 (4)
C9	0.08370 (18)	0.02822 (10)	0.8878 (2)	0.0206 (4)
H9A	0.1404	0.0281	0.9790	0.025*
C10	0.04344 (18)	−0.03919 (11)	0.8171 (2)	0.0232 (4)
H10A	0.0748	−0.0849	0.8598	0.028*
O1W	0.15531 (13)	0.42836 (7)	0.67062 (15)	0.0240 (3)
H1W1	0.0971	0.3950	0.6774	0.036*
H2W1	0.1630	0.4380	0.5829	0.036*
H1O2	0.170 (2)	0.4836 (15)	1.304 (3)	0.047 (9)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ni1	0.01935 (18)	0.01096 (18)	0.01281 (16)	0.000	−0.00102 (12)	0.000
O1	0.0240 (7)	0.0128 (6)	0.0126 (6)	0.0004 (5)	−0.0033 (5)	−0.0004 (5)
O2	0.0320 (8)	0.0146 (7)	0.0156 (6)	−0.0001 (6)	−0.0007 (6)	−0.0040 (6)
N1	0.0177 (7)	0.0109 (7)	0.0161 (7)	−0.0006 (6)	0.0012 (6)	−0.0003 (6)
C1	0.0189 (8)	0.0149 (9)	0.0129 (8)	0.0002 (7)	0.0002 (7)	0.0020 (7)
C2	0.0201 (9)	0.0156 (9)	0.0148 (8)	−0.0007 (7)	−0.0012 (7)	0.0009 (7)
C3	0.0192 (9)	0.0142 (9)	0.0145 (8)	−0.0009 (7)	0.0020 (7)	−0.0020 (7)
C4	0.0260 (10)	0.0209 (10)	0.0111 (8)	0.0015 (8)	−0.0011 (7)	0.0013 (7)
C5	0.0256 (10)	0.0168 (9)	0.0139 (8)	0.0010 (7)	0.0006 (7)	0.0047 (7)
C6	0.0189 (8)	0.0154 (9)	0.0126 (7)	−0.0004 (7)	0.0004 (6)	0.0010 (7)
C7	0.0215 (9)	0.0132 (9)	0.0158 (8)	0.0007 (7)	0.0009 (7)	0.0040 (7)
C8	0.0192 (9)	0.0151 (9)	0.0188 (9)	0.0006 (7)	0.0011 (7)	0.0016 (7)
C9	0.0224 (9)	0.0173 (9)	0.0207 (9)	0.0005 (8)	0.0007 (7)	0.0022 (8)
C10	0.0293 (11)	0.0153 (9)	0.0252 (10)	0.0014 (8)	0.0055 (8)	0.0039 (8)
O1W	0.0312 (8)	0.0175 (7)	0.0232 (7)	−0.0055 (6)	0.0050 (6)	0.0009 (6)

Geometric parameters (Å, °) top

Ni1—O1	1.8436 (12)	C4—C5	1.369 (3)
Ni1—O1ⁱ	1.8436 (12)	C4—H4A	0.9300
Ni1—N1ⁱ	1.8474 (15)	C5—C6	1.417 (3)
Ni1—N1	1.8474 (15)	C5—H5A	0.9300
O1—C1	1.324 (2)	C6—C7	1.414 (2)
O2—C3	1.359 (2)	C7—H7A	0.9300
O2—H1O2	0.74 (3)	C8—C8ⁱ	1.392 (4)
N1—C7	1.317 (2)	C8—C9	1.394 (2)
N1—C8	1.422 (2)	C9—C10	1.382 (3)
C1—C2	1.399 (2)	C9—H9A	0.9300
C1—C6	1.416 (2)	C10—C10ⁱ	1.387 (4)
C2—C3	1.383 (2)	C10—H10A	0.9300
C2—H2A	0.9300	O1W—H1W1	0.8771
C3—C4	1.404 (3)	O1W—H2W1	0.8309

Cg1···Cg4ⁱⁱ	3.7364 (11)	Cg4···Cg4^v	3.7750 (11)
Cg2···Cg2ⁱⁱ	3.7380 (9)	Ni1···O1Wⁱ	3.7635 (13)
Cg2···Cg3ⁱⁱⁱ	3.7381 (9)	O1···O1ⁱ	2.4319 (18)
Cg3···Cg4^iv	3.5766 (10)	N1···N1ⁱ	2.525 (2)

O1—Ni1—O1ⁱ	82.53 (8)	C5—C4—H4A	120.5
O1—Ni1—N1ⁱ	174.29 (5)	C3—C4—H4A	120.5
O1ⁱ—Ni1—N1ⁱ	95.89 (7)	C4—C5—C6	121.82 (17)
O1—Ni1—N1	95.89 (7)	C4—C5—H5A	119.1
O1ⁱ—Ni1—N1	174.29 (6)	C6—C5—H5A	119.1
N1ⁱ—Ni1—N1	86.21 (9)	C7—C6—C1	123.15 (17)
C1—O1—Ni1	127.44 (11)	C7—C6—C5	118.38 (16)
C3—O2—H1O2	111 (2)	C1—C6—C5	118.47 (16)
C7—N1—C8	121.12 (15)	N1—C7—C6	124.97 (17)
C7—N1—Ni1	125.63 (13)	N1—C7—H7A	117.5
C8—N1—Ni1	113.24 (12)	C6—C7—H7A	117.5
O1—C1—C2	118.13 (16)	C8ⁱ—C8—C9	119.92 (11)
O1—C1—C6	122.74 (16)	C8ⁱ—C8—N1	113.20 (9)
C2—C1—C6	119.12 (17)	C9—C8—N1	126.87 (17)
C3—C2—C1	120.89 (17)	C10—C9—C8	119.37 (18)
C3—C2—H2A	119.6	C10—C9—H9A	120.3
C1—C2—H2A	119.6	C8—C9—H9A	120.3
O2—C3—C2	122.42 (17)	C9—C10—C10ⁱ	120.43 (11)
O2—C3—C4	117.00 (16)	C9—C10—H10A	119.8
C2—C3—C4	120.59 (17)	C10ⁱ—C10—H10A	119.8
C5—C4—C3	119.06 (17)	H1W1—O1W—H2W1	114.3

O1ⁱ—Ni1—O1—C1	−176.47 (18)	O1—C1—C6—C5	178.70 (17)
N1ⁱ—Ni1—N1—C7	−176.59 (19)	C2—C1—C6—C5	−1.7 (3)
O1—Ni1—N1—C8	177.60 (12)	C4—C5—C6—C7	−177.71 (18)
N1ⁱ—Ni1—N1—C8	2.93 (9)	C4—C5—C6—C1	2.4 (3)
Ni1—O1—C1—C2	−176.01 (12)	C8—N1—C7—C6	−175.09 (17)
Ni1—O1—C1—C6	3.6 (3)	Ni1—N1—C7—C6	4.4 (3)
O1—C1—C2—C3	179.49 (17)	C1—C6—C7—N1	−3.0 (3)
C6—C1—C2—C3	−0.1 (3)	C5—C6—C7—N1	177.10 (18)
C1—C2—C3—O2	−178.73 (16)	C7—N1—C8—C8ⁱ	171.2 (2)
C1—C2—C3—C4	1.4 (3)	Ni1—N1—C8—C8ⁱ	−8.3 (3)
O2—C3—C4—C5	179.35 (17)	C7—N1—C8—C9	−7.6 (3)
C2—C3—C4—C5	−0.8 (3)	Ni1—N1—C8—C9	172.86 (16)
C3—C4—C5—C6	−1.1 (3)	C8ⁱ—C8—C9—C10	−5.1 (3)
O1—C1—C6—C7	−1.2 (3)	N1—C8—C9—C10	173.65 (18)
C2—C1—C6—C7	178.37 (17)	C8—C9—C10—C10ⁱ	−1.6 (3)

Symmetry codes: (i) −x, y, −z+3/2; (ii) −x+1/2, −y+1/2, −z+2; (iii) x+1/2, −y+1/2, z−1/2; (iv) x−1/2, −y+1/2, z−3/2; (v) −x, y, −z+5/2.

Hydrogen-bond geometry (Å, °) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O1	0.88	2.40	3.0733 (18)	133
O1W—H1W1···O1ⁱ	0.88	1.97	2.8072 (19)	160
O1W—H2W1···O2^vi	0.83	2.17	2.9985 (19)	173
C9—H9A···O2^vii	0.93	2.60	3.394 (2)	144

Symmetry codes: (i) −x, y, −z+3/2; (vi) x, y, z−1; (vii) −x+1/2, y−1/2, −z+5/2.

Table 1
Selected geometric parameters (Å) top

Cg1···Cg4ⁱ	3.7364 (11)	Cg4···Cg4^iv	3.7750 (11)
Cg2···Cg2ⁱ	3.7380 (9)	Ni1···O1W^v	3.7635 (13)
Cg2···Cg3ⁱⁱ	3.7381 (9)	O1···O1^v	2.4319 (18)
Cg3···Cg4ⁱⁱⁱ	3.5766 (10)	N1···N1^v	2.525 (2)

Symmetry codes: (i) −x+1/2, −y+1/2, −z+2; (ii) x+1/2, −y+1/2, z−1/2; (iii) x−1/2, −y+1/2, z−3/2; (iv) −x, y, −z+5/2; (v) −x, y, −z+3/2.

Table 2
Hydrogen-bond geometry (Å, °) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O1	0.88	2.40	3.0733 (18)	133
O1W—H1W1···O1^v	0.88	1.97	2.8072 (19)	160
O1W—H2W1···O2^vi	0.83	2.17	2.9985 (19)	173
C9—H9A···O2^vii	0.93	2.60	3.394 (2)	144

Symmetry codes: (v) −x, y, −z+3/2; (vi) x, y, z−1; (vii) −x+1/2, y−1/2, −z+5/2.

supplementary materials

{5,5'-Dihydroxy-2,2'-[o-phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II) dihydrate

H.-K. Fun, R. Kia, V. Mirkhani and H. Zargoshi

	Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering scheme. Intermolecular hydrogen bonds are drawn as dashed lines.
	Fig. 2. The crystal packing viewed down the b axis, showing one-dimensional extended chains involving the directed four membered O—H···O—H hydrogen bonds along the c axis. Intermolecular interactions are drawn as dashed lines.