A second monoclinic polymorph of {2,6-bis[(2,4,5-trifluoro­phen­yl)imino­meth­yl]pyridine-κ³N,N′,N′′}dichloridonickel(II)

The asymmetric unit of the title compound, [NiCl₂(C₁₉H₉F₆N₃)], contains one half-mol­ecule residing on a crystallographic twofold rotation axis. The title compound crystallizes in space group C2/c while the previously reported polymorph was reported in P2₁/c [Baldovino-Pantaleón et al. (2006). Adv. Synth. Catal. 348, 236–242]. The Ni²⁺ ion exhibits a penta­coordinate distorted trigonal–bipyramidal NiCl₂N₃ geometry, with two Cl atoms in the equatorial plane. In the crystal, mol­ecules are linked by inter­molecular C—F...π [F...centroid = 2.9676 (14) Å] inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.025
• wR factor = 0.058
• Data-to-parameter ratio = 12.3

checkCIF/PLATON results

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S1. Comment

For the last decade our research group has focused on the design, synthesis and use of pincer-type ligands and their transition metal complexes for novel organic transformations (Morales-Morales 2008; Serrano-Becerra & Morales-Morales, 2009). The selection of these ligands has been done on the basis of the robustness that they confer to the transition metal complexes they form (Baldovino-Pantaleón, et al., 2005, 2006). In recent years this kind of complexes have gained more interest particularly those derived from Ni, due to the importance that cross-coupling reactions have gained in important organic transformations of potential industrial relevance and the potential application of the nickel derivatives for the same sort of process regularly catalized by analogous palladium derivatives, but using a far more cheaper metal (Gómez-Benítez et al., 2006). The title compound is a polymorphous of a compound described previously (Baldovino-Pantaleón, et al., 2006).

The molecular structure of I is shown in figure 1 with the numbering scheme. In comparison, compound II described previously (Baldovino-Pantaleón, et al., 2006), was crystallized in a monoclinic (P 2₁/c), while compound I, crystallizes in space group C 2/c. The asymmetric unit consists of a half molecule with Ni—N1—C4—H4 in a special position (1/2, y, 1/4), and by two fold axis the complete molecule is generated. The Ni atom is found in a pentacoordinated distorted bipyramidal geometry with the two chlorides occupying the equatorial positions. While the fragment N1—Ni—N2—N2A is planar, the pyridine ring is slightly rotated by 5.4 (1)°. The 2,4,5-trifluorophenyl ring is not coplanar and is forming a dihedral angle of 39.41 (5)° with the coordination metallic center, while in II, the fluorophenyl rings have dihedral angles of 14.4 (2)° and 13.4 (2)° with the coordination metallic center. The bond distances Ni—N(imino) in I are slightly shorter than in II. In absence of clasic aceptor-donor H atom, the weak interactions become very important stabilizing the crystal structure. The molecules in the crystal structure are linked by C—H—F—C, C—H—π, C—F—π and C—F—F—C intermolecular interactions (Table 1).

Related literature

For related studies, see Baldovino-Pantaleón et al. (2005, 2006); Morales-Morales (2008); Serrano-Becerra & Morales-Morales (2009). For catalysis reactions, see; Gómez-Benítez et al. (2006). For the previously reported polymorph, see; Baldovino-Pantaleón et al. (2006).

S2. Experimental

A solution of the ligand {C₅H₃N-2,6-(CH=N—C₆H₂-2,4,5-F₃)₂} (120 mg, 0.33 mmol) in anhydrous CH₂Cl₂ (10 ml) was added to a stirred solution of NiCl₂.6 H₂O(0.078 g, 0.33 mmol) in absolute methanol (10 ml). The resulting green solution was stirred at room temperature for 2 h. After this time a red suspension is noted and the solvent evaporated under vacuum. The product was purified by recrystallization from MeOH; the resulting precipitated was filtered and washed with hexane (3 X 5 ml) and dried under vacuum. Crystals suitable for single-crystal X-ray diffraction studies were obtained from a dichloromethane/ methanol (4:1) solution. A red solid was obtained; yield: 142 mg (88%); mp: 240°C

S3. Refinement

H atoms were included in calculated positions (C—H = 0.93 Å), and refined using a riding model,with U_iso(H) = 1.2U_eq of the carrier atom.

Computing details

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. The molecular structure of I with the numbering scheme. Displacement ellipsoids are shown at the 40% probability level. H atoms have been omitted for clarity.

{2,6-Bis[(2,4,5-trifluorophenyl)iminomethyl]pyridine- κ³N,N',N''}dichloridonickel(II)

Crystal data

[NiCl2(C19H9F6N3)]	F(000) = 1040
Mr = 522.90	Dx = 1.810 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 5009 reflections
a = 18.0947 (13) Å	θ = 2.6–32.1°
b = 8.8967 (6) Å	µ = 1.36 mm^−1
c = 12.1638 (9) Å	T = 298 K
β = 101.421 (2)°	Prism, red
V = 1919.4 (2) Å^3	0.32 × 0.16 × 0.06 mm
Z = 4

Data collection

Bruker SMART APEX CCD area-detector diffractometer	1751 independent reflections
Radiation source: fine-focus sealed tube	1482 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
Detector resolution: 0.83 pixels mm^-1	θmax = 25.3°, θmin = 2.3°
ω scans	h = −21→21
Absorption correction: analytical (SHELXTL; Sheldrick, 2008)	k = −10→10
Tmin = 0.740, Tmax = 0.921	l = −14→14
7821 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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.058	H-atom parameters constrained
S = 0.96	w = 1/[σ^2(Fo^2) + (0.034P)^2] where P = (Fo^2 + 2Fc^2)/3
1751 reflections	(Δ/σ)max < 0.001
142 parameters	Δρmax = 0.23 e Å^−3
0 restraints	Δρmin = −0.20 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	0.5000	0.68998 (3)	0.2500	0.03615 (12)
Cl1	0.42526 (3)	0.79023 (6)	0.35781 (4)	0.06007 (17)
F1	0.62550 (7)	0.60471 (13)	0.63576 (9)	0.0642 (3)
F2	0.75608 (7)	1.06173 (13)	0.66763 (10)	0.0688 (4)
F3	0.72148 (8)	1.09768 (14)	0.44569 (11)	0.0767 (4)
N1	0.5000	0.4707 (2)	0.2500	0.0352 (5)
N2	0.58620 (8)	0.63599 (16)	0.39784 (11)	0.0372 (3)
C2	0.54313 (10)	0.39674 (18)	0.33462 (14)	0.0384 (4)
C3	0.54303 (12)	0.2412 (2)	0.33833 (16)	0.0505 (5)
H3	0.5714	0.1902	0.3991	0.061*
C4	0.5000	0.1634 (3)	0.2500	0.0586 (8)
H4	0.5000	0.0588	0.2500	0.070*
C5	0.58923 (10)	0.4948 (2)	0.41731 (13)	0.0399 (4)
H5	0.6196	0.4559	0.4817	0.048*
C6	0.63018 (9)	0.7410 (2)	0.47162 (14)	0.0376 (4)
C7	0.64917 (10)	0.7265 (2)	0.58667 (15)	0.0428 (4)
C8	0.69027 (11)	0.8327 (2)	0.65465 (16)	0.0513 (5)
H8	0.7015	0.8207	0.7321	0.062*
C9	0.71419 (10)	0.9570 (2)	0.60497 (16)	0.0478 (5)
C10	0.69631 (11)	0.9745 (2)	0.49109 (16)	0.0483 (5)
C11	0.65417 (10)	0.8698 (2)	0.42393 (15)	0.0461 (5)
H11	0.6416	0.8847	0.3468	0.055*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0457 (2)	0.02916 (18)	0.03209 (19)	0.000	0.00412 (14)	0.000
Cl1	0.0713 (4)	0.0718 (4)	0.0386 (3)	0.0258 (3)	0.0145 (2)	0.0021 (2)
F1	0.0917 (9)	0.0633 (8)	0.0368 (6)	−0.0145 (7)	0.0106 (6)	0.0031 (5)
F2	0.0692 (8)	0.0631 (8)	0.0648 (8)	−0.0106 (6)	−0.0090 (6)	−0.0235 (6)
F3	0.0997 (10)	0.0570 (8)	0.0663 (8)	−0.0309 (7)	−0.0009 (7)	0.0030 (6)
N1	0.0434 (12)	0.0312 (10)	0.0307 (10)	0.000	0.0065 (9)	0.000
N2	0.0413 (8)	0.0373 (8)	0.0316 (8)	0.0031 (7)	0.0036 (6)	−0.0016 (6)
C2	0.0476 (10)	0.0339 (10)	0.0336 (9)	0.0044 (8)	0.0077 (8)	0.0027 (7)
C3	0.0710 (14)	0.0346 (10)	0.0429 (11)	0.0078 (10)	0.0041 (10)	0.0056 (8)
C4	0.088 (2)	0.0300 (14)	0.0558 (18)	0.000	0.0083 (16)	0.000
C5	0.0465 (10)	0.0387 (10)	0.0320 (9)	0.0088 (8)	0.0013 (8)	0.0018 (8)
C6	0.0361 (10)	0.0380 (9)	0.0360 (9)	0.0060 (8)	0.0004 (8)	−0.0033 (8)
C7	0.0464 (11)	0.0434 (11)	0.0372 (10)	0.0040 (8)	0.0051 (8)	−0.0018 (8)
C8	0.0555 (12)	0.0616 (13)	0.0332 (10)	0.0073 (10)	−0.0002 (9)	−0.0080 (9)
C9	0.0424 (11)	0.0463 (12)	0.0501 (11)	0.0038 (9)	−0.0017 (9)	−0.0147 (9)
C10	0.0491 (11)	0.0427 (11)	0.0499 (12)	−0.0027 (9)	0.0022 (9)	−0.0009 (9)
C11	0.0517 (11)	0.0448 (11)	0.0372 (10)	0.0001 (9)	−0.0018 (8)	0.0006 (8)

Geometric parameters (Å, º)

Ni1—N1	1.9508 (19)	C3—C4	1.382 (2)
Ni1—N2^i	2.1878 (13)	C3—H3	0.9300
Ni1—N2	2.1878 (13)	C4—C3^i	1.382 (2)
Ni1—Cl1^i	2.2464 (5)	C4—H4	0.9300
Ni1—Cl1	2.2464 (5)	C5—H5	0.9300
F1—C7	1.347 (2)	C6—C7	1.379 (2)
F2—C9	1.3400 (19)	C6—C11	1.393 (3)
F3—C10	1.347 (2)	C7—C8	1.374 (3)
N1—C2^i	1.3354 (18)	C8—C9	1.370 (3)
N1—C2	1.3354 (18)	C8—H8	0.9300
N2—C5	1.277 (2)	C9—C10	1.368 (3)
N2—C6	1.424 (2)	C10—C11	1.367 (3)
C2—C3	1.384 (3)	C11—H11	0.9300
C2—C5	1.462 (2)
N1—Ni1—N2^i	77.32 (4)	C3—C4—H4	120.1
N1—Ni1—N2	77.32 (4)	C3^i—C4—H4	120.1
N2^i—Ni1—N2	154.64 (8)	N2—C5—C2	117.50 (15)
N1—Ni1—Cl1^i	113.393 (16)	N2—C5—H5	121.2
N2^i—Ni1—Cl1^i	91.20 (4)	C2—C5—H5	121.2
N2—Ni1—Cl1^i	98.82 (4)	C7—C6—C11	117.64 (16)
N1—Ni1—Cl1	113.393 (16)	C7—C6—N2	125.03 (17)
N2^i—Ni1—Cl1	98.82 (4)	C11—C6—N2	117.31 (16)
N2—Ni1—Cl1	91.20 (4)	F1—C7—C8	117.93 (17)
Cl1^i—Ni1—Cl1	133.21 (3)	F1—C7—C6	119.18 (16)
C2^i—N1—C2	121.0 (2)	C8—C7—C6	122.88 (18)
C2^i—N1—Ni1	119.52 (10)	C9—C8—C7	118.05 (18)
C2—N1—Ni1	119.52 (10)	C9—C8—H8	121.0
C5—N2—C6	122.00 (15)	C7—C8—H8	121.0
C5—N2—Ni1	111.45 (11)	F2—C9—C10	119.38 (18)
C6—N2—Ni1	126.33 (11)	F2—C9—C8	120.18 (18)
N1—C2—C3	120.88 (17)	C10—C9—C8	120.44 (17)
N1—C2—C5	113.77 (15)	F3—C10—C11	120.20 (17)
C3—C2—C5	125.34 (16)	F3—C10—C9	118.48 (16)
C4—C3—C2	118.68 (18)	C11—C10—C9	121.32 (18)
C4—C3—H3	120.7	C10—C11—C6	119.65 (17)
C2—C3—H3	120.7	C10—C11—H11	120.2
C3—C4—C3^i	119.8 (3)	C6—C11—H11	120.2
N2^i—Ni1—N1—C2^i	4.58 (9)	Ni1—N2—C5—C2	6.53 (19)
N2—Ni1—N1—C2^i	−175.42 (9)	N1—C2—C5—N2	−3.1 (2)
Cl1^i—Ni1—N1—C2^i	−81.18 (9)	C3—C2—C5—N2	175.64 (17)
Cl1—Ni1—N1—C2^i	98.82 (9)	C5—N2—C6—C7	−33.8 (3)
N2^i—Ni1—N1—C2	−175.42 (9)	Ni1—N2—C6—C7	140.38 (15)
N2—Ni1—N1—C2	4.58 (9)	C5—N2—C6—C11	147.89 (17)
Cl1^i—Ni1—N1—C2	98.82 (9)	Ni1—N2—C6—C11	−37.9 (2)
Cl1—Ni1—N1—C2	−81.18 (9)	C11—C6—C7—F1	178.61 (16)
N1—Ni1—N2—C5	−6.01 (11)	N2—C6—C7—F1	0.3 (3)
N2^i—Ni1—N2—C5	−6.01 (11)	C11—C6—C7—C8	−0.1 (3)
Cl1^i—Ni1—N2—C5	−118.15 (11)	N2—C6—C7—C8	−178.39 (17)
Cl1—Ni1—N2—C5	107.72 (12)	F1—C7—C8—C9	−179.78 (17)
N1—Ni1—N2—C6	179.28 (14)	C6—C7—C8—C9	−1.1 (3)
N2^i—Ni1—N2—C6	179.28 (14)	C7—C8—C9—F2	−178.30 (16)
Cl1^i—Ni1—N2—C6	67.14 (13)	C7—C8—C9—C10	1.0 (3)
Cl1—Ni1—N2—C6	−66.99 (13)	F2—C9—C10—F3	−0.2 (3)
C2^i—N1—C2—C3	−1.51 (13)	C8—C9—C10—F3	−179.49 (18)
Ni1—N1—C2—C3	178.49 (13)	F2—C9—C10—C11	179.53 (17)
C2^i—N1—C2—C5	177.34 (16)	C8—C9—C10—C11	0.2 (3)
Ni1—N1—C2—C5	−2.66 (16)	F3—C10—C11—C6	178.29 (17)
N1—C2—C3—C4	3.0 (2)	C9—C10—C11—C6	−1.4 (3)
C5—C2—C3—C4	−175.74 (15)	C7—C6—C11—C10	1.3 (3)
C2—C3—C4—C3^i	−1.44 (12)	N2—C6—C11—C10	179.76 (16)
C6—N2—C5—C2	−178.49 (15)

Symmetry code: (i) −x+1, y, −z+1/2.