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The title compound, [Ni(C5HF6O2)2(C2H3N)2], was obtained as an unintentional by-product in the reaction of Ni(hfac)2 (hfac is hexa­fluoro­acetyl­acetonate) with pyrazine N,N′-dioxide in acetonitrile. The mol­ecule is centrosymmetric and the ligands are trans to one another, with the NiII atom on a position with 2/m symmetry. The CF3 groups are in a symmetry-imposed eclipsed conformation. The acetonitrile methyl group is involved in weak non-classical C—H...O inter­molecular hydrogen bonding to the propane­dionate O atoms. This forms a chain synthon parallel to the b axis. The chains are further arranged into sheets parallel to the bc plane.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807038226/ci2433sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807038226/ci2433Isup2.hkl
Contains datablock I

CCDC reference: 660079

Key indicators

  • Single-crystal X-ray study
  • T = 90 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.026
  • wR factor = 0.068
  • Data-to-parameter ratio = 10.7

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density .... 2.09 PLAT164_ALERT_4_C Nr. of Refined C-H H-Atoms in Heavy-At Struct... 2
Alert level G PLAT794_ALERT_5_G Check Predicted Bond Valency for Ni1 (2) 2.24
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 2 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 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

Comment top

The title compound, (I), is centrosymmetric with a trans orientation of the ligands, and is shown in Fig. 1. Although the ligand disposition around Ni1 is not perfectly perpendicular (see Table 1), the mean plane through the C and O atoms of both hexafluoroacetylacetonate (hfac) ligands and the Ni1 atom is perpendicular to the plane through the acetonitrile-Ni plane. The CF3 groups of the hfac ligands are in a symmetry imposed eclipsed conformation.

trans-[Cp(PPh3)2RuCN]2Ni(hfac)2 is the only known structurally related species with a similar trans Ni(hfac)2(cyano)2 core (Chen et al., 2000). Although the substituents on the cyano group distort the geometry, the central hfac-Ni core is also perpendicular to the N—Ni—N vector as seen in (I). A related ruthenium analogue, cis-Ru(hfac)2(MeCN)2 (Baird et al., 1999) is a cis-isomer.

There is weak bifurcated intermolecular hydrogen bonding between the acetonitrile methyl group and the propanedionato oxygen (Fig. 2, Table 2), linking the molecules into a chain synthon parallel to the b-axis. The chains are further arranged into sheets parallel to the bc plane.

Related literature top

For related literature, see: Baird et al. (1999); Chen et al. (2000).

Experimental top

A solution of Ni(hfac)2 was added to a solution of 2 equivalents of pyrazine-dioxide in acetonitrile at room temperature. Slow evaporation of the resulting solution over five days resulted in a large crop of green parallelepiped shaped crystals (yield 73%).

Refinement top

The dionato H atoms were placed in geometrically idealized positions (C—H = 0.95 Å) and constrained to ride on their parent atom, with Uiso(H) = 1.2Ueq(C). Acetonitrile methyl H atoms were freely refined due to their involvement in H-bonding. The highest residual density peak and the deepest hole are located 1.00 and 0.82 Å, respectively, from atom F1.

Structure description top

The title compound, (I), is centrosymmetric with a trans orientation of the ligands, and is shown in Fig. 1. Although the ligand disposition around Ni1 is not perfectly perpendicular (see Table 1), the mean plane through the C and O atoms of both hexafluoroacetylacetonate (hfac) ligands and the Ni1 atom is perpendicular to the plane through the acetonitrile-Ni plane. The CF3 groups of the hfac ligands are in a symmetry imposed eclipsed conformation.

trans-[Cp(PPh3)2RuCN]2Ni(hfac)2 is the only known structurally related species with a similar trans Ni(hfac)2(cyano)2 core (Chen et al., 2000). Although the substituents on the cyano group distort the geometry, the central hfac-Ni core is also perpendicular to the N—Ni—N vector as seen in (I). A related ruthenium analogue, cis-Ru(hfac)2(MeCN)2 (Baird et al., 1999) is a cis-isomer.

There is weak bifurcated intermolecular hydrogen bonding between the acetonitrile methyl group and the propanedionato oxygen (Fig. 2, Table 2), linking the molecules into a chain synthon parallel to the b-axis. The chains are further arranged into sheets parallel to the bc plane.

For related literature, see: Baird et al. (1999); Chen et al. (2000).

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT-Plus (Bruker, 2006); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Bruker, 2003); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: publCIF (Westrip, 2007).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids. Only symmetry unique atoms are labelled. Hydrogen atoms are displayed as spheres of arbitrary radius.
[Figure 2] Fig. 2. Diagram showing the hydrogen-bonding pattern (dashed lines) linking the molecules into an extended chain along the b axis.
trans-Bis(acetonitrile-κN)bis(1,1,1,5,5,5-hexafluoropentane-2,4-\ dionato-κ2O,O')nickel(II) top
Crystal data top
[Ni(C5HF6O2)2(C2H3N)2]F(000) = 1096
Mr = 554.93Dx = 1.806 Mg m3
Orthorhombic, CmcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2bc 2Cell parameters from 7181 reflections
a = 20.4841 (6) Åθ = 2.9–30.0°
b = 7.1692 (2) ŵ = 1.08 mm1
c = 13.9008 (4) ÅT = 90 K
V = 2041.4 (1) Å3Parallelepiped, light green
Z = 40.21 × 0.20 × 0.10 mm
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer
956 independent reflections
Radiation source: normal-focus sealed tube890 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
Detector resolution: 8.3 pixels mm-1θmax = 25.3°, θmin = 2.0°
ω scansh = 2424
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
k = 88
Tmin = 0.805, Tmax = 0.900l = 1616
14542 measured reflections
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)] = 0.026Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.069H atoms treated by a mixture of independent and constrained refinement
S = 1.08 w = 1/[σ2(Fo2) + (0.0363P)2 + 3.0631P]
where P = (Fo2 + 2Fc2)/3
956 reflections(Δ/σ)max = 0.001
89 parametersΔρmax = 0.50 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
[Ni(C5HF6O2)2(C2H3N)2]V = 2041.4 (1) Å3
Mr = 554.93Z = 4
Orthorhombic, CmcaMo Kα radiation
a = 20.4841 (6) ŵ = 1.08 mm1
b = 7.1692 (2) ÅT = 90 K
c = 13.9008 (4) Å0.21 × 0.20 × 0.10 mm
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer
956 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
890 reflections with I > 2σ(I)
Tmin = 0.805, Tmax = 0.900Rint = 0.025
14542 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0260 restraints
wR(F2) = 0.069H atoms treated by a mixture of independent and constrained refinement
S = 1.08Δρmax = 0.50 e Å3
956 reflectionsΔρmin = 0.24 e Å3
89 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
Ni10.50000.00000.50000.01765 (16)
C10.37064 (9)0.1065 (2)0.43182 (13)0.0243 (4)
C20.33788 (13)0.00000.50000.0294 (6)
H20.29150.00000.50000.035*
C30.33054 (10)0.2315 (3)0.36471 (15)0.0344 (5)
C40.50000.3617 (4)0.63509 (18)0.0225 (5)
C50.50000.5185 (4)0.7013 (2)0.0268 (6)
H5A0.5364 (12)0.514 (4)0.741 (2)0.061 (8)*
H5B0.50000.628 (6)0.665 (3)0.058 (12)*
F10.26677 (6)0.1999 (2)0.36833 (12)0.0604 (5)
F20.33928 (7)0.41007 (19)0.38887 (11)0.0531 (4)
F30.35020 (7)0.2156 (2)0.27393 (9)0.0495 (4)
N10.50000.2359 (3)0.58532 (15)0.0242 (5)
O10.43089 (6)0.12008 (17)0.41713 (9)0.0226 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ni10.0161 (3)0.0194 (3)0.0174 (2)0.0000.0000.00028 (17)
C10.0214 (9)0.0249 (9)0.0266 (10)0.0009 (7)0.0029 (7)0.0029 (8)
C20.0176 (13)0.0353 (15)0.0353 (15)0.0000.0000.0019 (12)
C30.0235 (10)0.0442 (13)0.0354 (11)0.0042 (9)0.0041 (8)0.0075 (10)
C40.0246 (13)0.0231 (13)0.0198 (12)0.0000.0000.0051 (11)
C50.0385 (17)0.0209 (13)0.0209 (14)0.0000.0000.0011 (11)
F10.0231 (7)0.0842 (11)0.0738 (10)0.0021 (7)0.0135 (7)0.0323 (9)
F20.0610 (9)0.0372 (8)0.0610 (9)0.0183 (7)0.0115 (7)0.0081 (7)
F30.0478 (8)0.0700 (9)0.0307 (7)0.0158 (7)0.0109 (6)0.0065 (6)
N10.0275 (12)0.0235 (12)0.0215 (11)0.0000.0000.0008 (10)
O10.0204 (6)0.0257 (7)0.0218 (6)0.0012 (5)0.0020 (5)0.0022 (5)
Geometric parameters (Å, º) top
Ni1—O1i2.0180 (12)C2—C1i1.390 (2)
Ni1—O12.0180 (12)C2—H20.95
Ni1—O1ii2.0180 (12)C3—F11.327 (2)
Ni1—O1iii2.0180 (12)C3—F31.329 (2)
Ni1—N12.066 (2)C3—F21.335 (3)
Ni1—N1ii2.066 (2)C4—N11.137 (3)
C1—O11.255 (2)C4—C51.453 (4)
C1—C21.390 (2)C5—H5A0.93 (3)
C1—C31.532 (3)C5—H5B0.93 (4)
O1i—Ni1—O190.90 (7)C2—C1—C3118.54 (18)
O1i—Ni1—O1ii89.10 (7)C1—C2—C1i122.3 (3)
O1—Ni1—O1ii180.0C1—C2—H2118.9
O1i—Ni1—O1iii180.00 (5)C1i—C2—H2118.9
O1—Ni1—O1iii89.10 (7)F1—C3—F3108.63 (18)
O1ii—Ni1—O1iii90.90 (7)F1—C3—F2106.62 (18)
O1i—Ni1—N191.23 (6)F3—C3—F2106.28 (18)
O1—Ni1—N188.77 (6)F1—C3—C1113.87 (18)
O1ii—Ni1—N191.23 (6)F3—C3—C1111.43 (17)
O1iii—Ni1—N188.77 (6)F2—C3—C1109.62 (17)
O1i—Ni1—N1ii88.77 (6)N1—C4—C5178.2 (3)
O1—Ni1—N1ii91.23 (6)C4—C5—H5A110.5 (18)
O1ii—Ni1—N1ii88.77 (6)C4—C5—H5B108 (2)
O1iii—Ni1—N1ii91.23 (6)H5A—C5—H5B110 (2)
N1—Ni1—N1ii180.0C4—N1—Ni1177.6 (2)
O1—C1—C2128.94 (18)C1—O1—Ni1124.34 (12)
O1—C1—C3112.50 (16)
Symmetry codes: (i) x, y, z+1; (ii) x+1, y, z+1; (iii) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5B···O1iv0.93 (4)2.56 (4)3.381 (3)147 (1)
C5—H5B···O1v0.93 (4)2.56 (4)3.381 (3)147 (1)
Symmetry codes: (iv) x+1, y+1, z+1; (v) x, y+1, z+1.

Experimental details

Crystal data
Chemical formula[Ni(C5HF6O2)2(C2H3N)2]
Mr554.93
Crystal system, space groupOrthorhombic, Cmca
Temperature (K)90
a, b, c (Å)20.4841 (6), 7.1692 (2), 13.9008 (4)
V3)2041.4 (1)
Z4
Radiation typeMo Kα
µ (mm1)1.08
Crystal size (mm)0.21 × 0.20 × 0.10
Data collection
DiffractometerBruker SMART APEX CCD area-detector
Absorption correctionMulti-scan
(SADABS; Bruker, 2004)
Tmin, Tmax0.805, 0.900
No. of measured, independent and
observed [I > 2σ(I)] reflections
14542, 956, 890
Rint0.025
(sin θ/λ)max1)0.600
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.026, 0.069, 1.08
No. of reflections956
No. of parameters89
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.50, 0.24

Computer programs: SMART (Bruker, 2003), SAINT-Plus (Bruker, 2006), SAINT-Plus, SHELXTL (Bruker, 2003), SHELXTL, publCIF (Westrip, 2007).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5B···O1i0.93 (4)2.56 (4)3.381 (3)146.5 (6)
C5—H5B···O1ii0.93 (4)2.56 (4)3.381 (3)146.5 (6)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1.
 

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