{4,4′-Dibromo-2,2′-[2,2-dimethyl­propane-1,3-diylbis(nitrilo­methanylyl­idene)]diphenolato-κ⁴O,N,N′,O′}nickel(II)

In the title compound, [Ni(C₁₉H₁₈Br₂N₂O₂)], the Ni^II ion, lying on a twofold rotation axis, is coordinated by two N atoms and two O atoms from the Schiff base ligand in a distorted square-planar geometry. Weak inter­molecular C—H...O hydrogen bonds stabilize the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.073
• wR factor = 0.211
• Data-to-parameter ratio = 21.6

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers .          2

Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.12
            Rint given   0.142
PLAT020_ALERT_3_C The value of Rint is greater than 0.12 .........       0.14
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds (x 1000) Ang ..          9
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          7
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         15
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          1
PLAT918_ALERT_3_C Reflection(s) # with I(obs) much smaller I(calc)          1

Alert level G
PLAT794_ALERT_5_G Note: Tentative Bond Valency for Ni1     (III)         2.86

   0 ALERT level A = Most likely a serious problem - resolve or explain
   1 ALERT level B = A potentially serious problem, consider carefully
   8 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   1 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   8 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Schiff base complexes are found to exhibit large applications such as catalytic properties (Cozzi, 2004). N,N'-Bis(5-bromo-2-hydroxybenzylidene)- 2,2-dimethylpropane-1,3-diamine ligand has been previously synthesized and structurally characterized by X-ray diffraction (Fun et al., 2008). The structure of a copper(II) complex of this Schiff base ligand has been also reported by Fun's group (Kargar et al., 2008).

Herein, we report the synthesis and crystal structure of an Ni(II) complex with this Schiff base ligand. The molecular structure of the title compound is shown in Fig. 1. The asymmetric unit of the title compound contains half of the molecule. The Ni^II ion, lying on a twofold rotation axis, is coordinated by two N atoms and two O atoms from a Schiff base ligand (Table 1). The coordination environment around the Ni^II ion can be described as distorted squar-planar. In the crystal, weak intermolecular C—H···O hydrogen bonds stabilize the structure (Table 2, Fig. 2).

Related literature

For the catalytic properties of Schiff base complexes, see: Cozzi (2004). For related structures see: Fun et al. (2008); Kargar et al. (2008). For the synthesis of the ligand, see: Fairhurst et al. (1995).

S2. Experimental

N,N'-Bis(5-bromo-2-hydroxybenzylidene)- 2,2-dimethylpropane-1,3-diamine was prepared according to the described procedure (Fairhurst et al., 1995). To a stirred ethanolic solution (30 ml) of 2,2-dimethylpropylenediamine (0.102 g, 1 mmol), 5-bromo-2-hydroxybenzaldehyde (0.402 g, 2 mmol) was added. The bright yellow solution was stirred and heated to reflux for 1 h. A yellow precipitate was obtained that was filtered off, washed with diethyl ether (yield: 70%; m.p.: 140 °C).

The title complex was prepared by the following procedure. The Schiff base ligand (0.467 g, 1 mmol) was dissolved in 20 ml ethanol. A solution of nickel(II) acetate (0.248 g, 1 mmol) in ethanol was added to the solution of ligand and the reaction mixture was refluxed for 1 h. The colored solution was concentrated to yield brown powders. The product washed with ethanol and air dried (yield: 95%; decomposition temperature: 242°C).

S3. Refinement

H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (aromatic), 0.97 (CH₂) and 0.96 (CH₃) Å and with U_iso(H) = 1.2 or 1.5U_eq(C).

Computing details

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. Molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. [Symmetry code: (i) -x, y, -z+1/2].
	Fig. 2. The packing diagram of the title compound. Hydrogen bonds are shown as blue dashed lines.

{4,4'-Dibromo-2,2'-[2,2-dimethylpropane-1,3- diylbis(nitrilomethanylylidene)]diphenolato- κ⁴O,N,N',O'}nickel(II)

Crystal data

[Ni(C19H18Br2N2O2)]	F(000) = 1040.0
Mr = 524.84	Dx = 1.820 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2575 reflections
a = 24.227 (6) Å	θ = 3.2–29.2°
b = 11.030 (3) Å	µ = 5.20 mm^−1
c = 7.535 (2) Å	T = 298 K
β = 107.939 (19)°	Plate, brown
V = 1915.6 (9) Å^3	0.30 × 0.20 × 0.15 mm
Z = 4

Data collection

Stoe IPDS-2 diffractometer	2575 independent reflections
Radiation source: fine-focus sealed tube	1892 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.142
ω scans	θmax = 29.2°, θmin = 3.2°
Absorption correction: numerical (X-SHAPE and X-RED32; Stoe & Cie, 2005)	h = −33→24
Tmin = 0.289, Tmax = 0.449	k = −15→13
7514 measured reflections	l = −10→10

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)] = 0.073	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.211	H-atom parameters constrained
S = 1.16	w = 1/[σ^2(Fo^2) + (0.0955P)^2 + 1.9321P] where P = (Fo^2 + 2Fc^2)/3
2575 reflections	(Δ/σ)max < 0.001
119 parameters	Δρmax = 0.74 e Å^−3
0 restraints	Δρmin = −0.99 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.0516 (4)	0.4164 (6)	0.2433 (9)	0.0606 (17)
H1A	0.0407	0.4647	0.1319	0.073*
H1B	0.0836	0.3650	0.2432	0.073*
H1C	0.0629	0.4685	0.3505	0.073*
C2	0.0000	0.3381 (7)	0.2500	0.0386 (14)
C3	−0.0173 (2)	0.2567 (5)	0.0764 (6)	0.0376 (10)
H3A	−0.0428	0.3023	−0.0268	0.045*
H3B	0.0173	0.2364	0.0438	0.045*
C4	−0.0989 (2)	0.1277 (5)	−0.0094 (7)	0.0411 (11)
H4	−0.1172	0.1946	−0.0780	0.049*
C5	−0.1317 (2)	0.0172 (5)	−0.0337 (7)	0.0425 (11)
C6	−0.1902 (3)	0.0171 (7)	−0.1506 (8)	0.0546 (14)
H6	−0.2078	0.0894	−0.2018	0.065*
C7	−0.2206 (3)	−0.0880 (7)	−0.1878 (9)	0.0591 (17)
C8	−0.1955 (3)	−0.1976 (7)	−0.1126 (9)	0.0587 (16)
H8	−0.2172	−0.2687	−0.1381	0.070*
C9	−0.1388 (3)	−0.2006 (6)	−0.0009 (8)	0.0518 (14)
H9	−0.1223	−0.2746	0.0462	0.062*
C10	−0.1048 (2)	−0.0934 (5)	0.0447 (7)	0.0404 (11)
N1	−0.04685 (19)	0.1431 (4)	0.0982 (5)	0.0357 (9)
O1	−0.05103 (17)	−0.1011 (3)	0.1491 (5)	0.0427 (8)
Ni1	0.0000	0.02440 (9)	0.2500	0.0336 (3)
Br1	−0.29838 (4)	−0.08575 (11)	−0.35030 (14)	0.0979 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.074 (5)	0.048 (4)	0.053 (3)	−0.013 (3)	0.010 (3)	0.002 (3)
C2	0.037 (3)	0.038 (4)	0.036 (3)	0.000	0.004 (3)	0.000
C3	0.041 (3)	0.035 (3)	0.036 (2)	0.000 (2)	0.0104 (19)	0.0032 (18)
C4	0.046 (3)	0.040 (3)	0.036 (2)	0.004 (2)	0.0100 (19)	0.0043 (19)
C5	0.038 (2)	0.046 (3)	0.039 (2)	−0.005 (2)	0.0036 (19)	−0.001 (2)
C6	0.040 (3)	0.058 (4)	0.054 (3)	0.000 (3)	−0.003 (2)	0.008 (3)
C7	0.031 (3)	0.073 (5)	0.060 (3)	−0.014 (3)	−0.007 (2)	−0.003 (3)
C8	0.045 (3)	0.060 (4)	0.064 (3)	−0.018 (3)	0.007 (3)	−0.005 (3)
C9	0.057 (4)	0.039 (3)	0.055 (3)	−0.007 (3)	0.011 (3)	−0.003 (2)
C10	0.040 (3)	0.044 (3)	0.036 (2)	−0.005 (2)	0.0105 (19)	−0.0033 (19)
N1	0.040 (2)	0.036 (2)	0.0277 (15)	−0.0035 (18)	0.0057 (14)	−0.0005 (14)
O1	0.0371 (19)	0.0349 (19)	0.0495 (19)	0.0004 (15)	0.0035 (15)	−0.0030 (14)
Ni1	0.0339 (5)	0.0315 (5)	0.0325 (4)	0.000	0.0060 (3)	0.000
Br1	0.0519 (5)	0.1002 (8)	0.1070 (7)	−0.0251 (5)	−0.0265 (4)	0.0188 (5)

Geometric parameters (Å, º)

C1—C2	1.533 (8)	C5—C6	1.421 (8)
C1—H1A	0.9600	C5—C10	1.423 (8)
C1—H1B	0.9600	C6—C7	1.354 (10)
C1—H1C	0.9600	C6—H6	0.9300
C2—C1^i	1.533 (8)	C7—C8	1.393 (11)
C2—C3	1.535 (7)	C7—Br1	1.906 (6)
C2—C3^i	1.535 (7)	C8—C9	1.372 (9)
C3—N1	1.476 (7)	C8—H8	0.9300
C3—H3A	0.9700	C9—C10	1.423 (8)
C3—H3B	0.9700	C9—H9	0.9300
C4—N1	1.284 (7)	C10—O1	1.300 (7)
C4—C5	1.435 (8)	Ni1—N1	1.874 (4)
C4—H4	0.9300	Ni1—O1	1.856 (4)
C2—C1—H1A	109.5	C7—C6—H6	119.9
C2—C1—H1B	109.5	C5—C6—H6	119.9
H1A—C1—H1B	109.5	C6—C7—C8	121.2 (6)
C2—C1—H1C	109.5	C6—C7—Br1	119.2 (5)
H1A—C1—H1C	109.5	C8—C7—Br1	119.5 (5)
H1B—C1—H1C	109.5	C9—C8—C7	119.9 (6)
C1—C2—C1^i	111.4 (8)	C9—C8—H8	120.0
C1—C2—C3	108.3 (3)	C7—C8—H8	120.0
C1^i—C2—C3	110.2 (3)	C8—C9—C10	121.7 (6)
C1—C2—C3^i	110.2 (3)	C8—C9—H9	119.2
C1^i—C2—C3^i	108.3 (3)	C10—C9—H9	119.2
C3—C2—C3^i	108.4 (6)	O1—C10—C5	123.6 (5)
N1—C3—C2	114.6 (4)	O1—C10—C9	119.4 (5)
N1—C3—H3A	108.6	C5—C10—C9	117.0 (5)
C2—C3—H3A	108.6	C4—N1—C3	117.2 (4)
N1—C3—H3B	108.6	C4—N1—Ni1	125.9 (4)
C2—C3—H3B	108.6	C3—N1—Ni1	116.0 (3)
H3A—C3—H3B	107.6	C10—O1—Ni1	128.0 (4)
N1—C4—C5	126.2 (5)	O1—Ni1—O1^i	83.5 (2)
N1—C4—H4	116.9	O1—Ni1—N1^i	166.70 (17)
C5—C4—H4	116.9	O1^i—Ni1—N1^i	93.97 (18)
C6—C5—C10	119.9 (6)	O1—Ni1—N1	93.97 (18)
C6—C5—C4	119.1 (6)	O1^i—Ni1—N1	166.70 (17)
C10—C5—C4	120.7 (5)	N1^i—Ni1—N1	91.3 (3)
C7—C6—C5	120.2 (6)
C1—C2—C3—N1	154.4 (5)	C8—C9—C10—C5	−1.2 (9)
C1^i—C2—C3—N1	−83.4 (6)	C5—C4—N1—C3	168.8 (5)
C3^i—C2—C3—N1	34.9 (3)	C5—C4—N1—Ni1	0.5 (7)
N1—C4—C5—C6	176.4 (5)	C2—C3—N1—C4	118.2 (5)
N1—C4—C5—C10	−8.9 (8)	C2—C3—N1—Ni1	−72.3 (5)
C10—C5—C6—C7	0.0 (9)	C5—C10—O1—Ni1	9.6 (7)
C4—C5—C6—C7	174.6 (6)	C9—C10—O1—Ni1	−172.6 (4)
C5—C6—C7—C8	0.3 (11)	C10—O1—Ni1—O1^i	179.3 (5)
C5—C6—C7—Br1	−178.4 (5)	C10—O1—Ni1—N1^i	99.5 (8)
C6—C7—C8—C9	−1.0 (11)	C10—O1—Ni1—N1	−13.9 (4)
Br1—C7—C8—C9	177.7 (5)	C4—N1—Ni1—O1	8.7 (4)
C7—C8—C9—C10	1.5 (10)	C3—N1—Ni1—O1	−159.7 (3)
C6—C5—C10—O1	178.3 (5)	C4—N1—Ni1—O1^i	87.3 (9)
C4—C5—C10—O1	3.7 (8)	C3—N1—Ni1—O1^i	−81.1 (9)
C6—C5—C10—C9	0.4 (8)	C4—N1—Ni1—N1^i	−159.1 (5)
C4—C5—C10—C9	−174.1 (5)	C3—N1—Ni1—N1^i	32.5 (3)
C8—C9—C10—O1	−179.1 (6)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3B···O1^ii	0.97	2.40	3.210 (6)	141

Symmetry code: (ii) −x, −y, −z.