metal-organic compounds
cis-Bis(azido-κN)bis(pyridine-2-carboxamide-κ2N1,O)nickel(II)
aDepartment of Chemistry, Laboratory of General and Inorganic Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
*Correspondence e-mail: zpopovic@chem.pmf.hr
The title compound, [Ni(N3)2(C6H6N2O)2], was obtained as the first crystalline product from the reaction of Ni(NO3)2·6H2O, picolinamide and NaN3 in aqueous media. After a few days in the mother liquor, crystals of the cis isomer transformed into the trans isomer [Đaković & Popović (2007). Acta Cryst. C63, m507–m509]. The Ni atom exhibits a distorted octahedral environment and contains two azide ions and two planar N,O-chelating picolinamide ligands, all cis related. The dihedral angle between the two chelate rings is 82.43 (7)°. Pairs of molecules are linked by N—H⋯N hydrogen bonds into cyclic R22(16) dimers, which are further packed into a three-dimensional framework by C(6) and C(8) chains by N—H⋯N hydrogen bonds.
Related literature
For information on the importance of et al. (2000). A trans isomer of the title compound [Ni(N3)2(C6H6N2O)2] has been reported by Đaković & Popović (2007). For related literature, see: Allen et al. (1987); Bernstein et al. (1995); Etter (1990).
in complexation, see YuwenExperimental
Crystal data
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Refinement
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Data collection: CrysAlisPro (Oxford Diffraction, 2007); cell CrysAlisPro; data reduction: CrysAlisPro; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2003).
Supporting information
10.1107/S1600536808000299/kp2158sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808000299/kp2158Isup2.hkl
The title compound was obtained by in situ reaction from NiII nitrate hexahydrate, sodium azide and picolinamide in a 1: 2: 2 molar ratio. All starting substances were dissolved in water. The sodium azide solution was added in small portions with stirring into the solution mixture of the picolinamide and NiII nitrate. In a few h the dark-green crystals of (I) were isolated. If the crystals are left in a mother liquor for a few days the dark-green crystals of (I) were transformed into the olive-green trans-isomer.
Aromatic H atoms were fixed in geometrically idealized positions and refined using a riding model with [C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C)]. The amide H atoms were placed in the positions indicated by difference electron-density maps and their positions were allowed to refine together with individual isotropic displacement parameters.
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell
CrysAlis PRO (Oxford Diffraction, 2007); data reduction: CrysAlis PRO (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Bruno et al., 2002); software used to prepare material for publication: PLATON (Spek, 2003).[Ni(N3)2(C6H6N2O)2] | F(000) = 792 |
Mr = 387.01 | Dx = 1.656 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 5015 reflections |
a = 14.3438 (5) Å | θ = 3.8–32.4° |
b = 6.6986 (2) Å | µ = 1.28 mm−1 |
c = 18.7969 (10) Å | T = 296 K |
β = 120.738 (3)° | Plate, blue |
V = 1552.34 (12) Å3 | 0.22 × 0.18 × 0.05 mm |
Z = 4 |
Oxford Diffraction Xcalibur diffractometer with Sapphire3 detector | 4516 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 2692 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
Detector resolution: 16.3426 pixels mm-1 | θmax = 30.0°, θmin = 3.8° |
CCD scans | h = −20→20 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) | k = −9→9 |
Tmin = 0.815, Tmax = 0.938 | l = −26→26 |
15901 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.068 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.89 | w = 1/[σ2(Fo2) + (0.0323P)2] where P = (Fo2 + 2Fc2)/3 |
4516 reflections | (Δ/σ)max < 0.001 |
242 parameters | Δρmax = 0.43 e Å−3 |
0 restraints | Δρmin = −0.30 e Å−3 |
[Ni(N3)2(C6H6N2O)2] | V = 1552.34 (12) Å3 |
Mr = 387.01 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 14.3438 (5) Å | µ = 1.28 mm−1 |
b = 6.6986 (2) Å | T = 296 K |
c = 18.7969 (10) Å | 0.22 × 0.18 × 0.05 mm |
β = 120.738 (3)° |
Oxford Diffraction Xcalibur diffractometer with Sapphire3 detector | 4516 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) | 2692 reflections with I > 2σ(I) |
Tmin = 0.815, Tmax = 0.938 | Rint = 0.034 |
15901 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.068 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.89 | Δρmax = 0.43 e Å−3 |
4516 reflections | Δρmin = −0.30 e Å−3 |
242 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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. |
x | y | z | Uiso*/Ueq | ||
Ni1 | 0.23220 (2) | 0.37068 (3) | 0.22317 (1) | 0.0317 (1) | |
O1 | 0.26131 (9) | 0.2742 (2) | 0.33739 (8) | 0.0434 (4) | |
O2 | 0.20315 (9) | 0.08148 (18) | 0.17407 (8) | 0.0398 (4) | |
N1 | 0.39913 (11) | 0.3396 (2) | 0.28785 (9) | 0.0334 (4) | |
N2 | 0.38916 (17) | 0.2368 (3) | 0.47094 (11) | 0.0477 (6) | |
N3 | 0.06825 (11) | 0.3406 (2) | 0.17609 (8) | 0.0323 (4) | |
N4 | 0.07207 (16) | −0.1400 (3) | 0.09546 (11) | 0.0461 (6) | |
N5 | 0.24200 (12) | 0.6613 (2) | 0.26310 (10) | 0.0428 (5) | |
N6 | 0.31950 (13) | 0.7291 (2) | 0.32014 (10) | 0.0385 (5) | |
N7 | 0.39487 (16) | 0.8009 (3) | 0.37649 (12) | 0.0648 (7) | |
N8 | 0.21165 (13) | 0.4829 (2) | 0.11250 (10) | 0.0447 (6) | |
N9 | 0.20157 (13) | 0.3801 (2) | 0.05837 (10) | 0.0423 (5) | |
N10 | 0.1963 (2) | 0.2815 (3) | 0.00574 (13) | 0.0815 (9) | |
C1 | 0.44295 (14) | 0.2970 (3) | 0.36860 (11) | 0.0342 (6) | |
C2 | 0.55345 (15) | 0.2892 (3) | 0.42221 (13) | 0.0468 (7) | |
C3 | 0.62099 (16) | 0.3289 (3) | 0.39169 (14) | 0.0531 (8) | |
C4 | 0.57737 (15) | 0.3711 (3) | 0.30972 (13) | 0.0482 (7) | |
C5 | 0.46602 (15) | 0.3750 (3) | 0.25924 (12) | 0.0403 (6) | |
C6 | 0.35865 (14) | 0.2657 (3) | 0.39230 (11) | 0.0352 (6) | |
C7 | 0.02452 (13) | 0.1678 (3) | 0.13675 (10) | 0.0341 (5) | |
C8 | −0.08351 (14) | 0.1241 (3) | 0.10454 (12) | 0.0467 (6) | |
C9 | −0.14833 (16) | 0.2628 (4) | 0.11367 (13) | 0.0573 (8) | |
C10 | −0.10408 (16) | 0.4361 (4) | 0.15429 (12) | 0.0512 (7) | |
C11 | 0.00463 (15) | 0.4720 (3) | 0.18414 (11) | 0.0426 (6) | |
C12 | 0.10687 (14) | 0.0314 (3) | 0.13626 (10) | 0.0340 (6) | |
H2 | 0.58190 | 0.25790 | 0.47780 | 0.0560* | |
H3 | 0.69590 | 0.32680 | 0.42690 | 0.0640* | |
H4 | 0.62190 | 0.39680 | 0.28820 | 0.0580* | |
H5 | 0.43630 | 0.40330 | 0.20330 | 0.0480* | |
H8 | −0.11240 | 0.00400 | 0.07720 | 0.0560* | |
H9 | −0.22170 | 0.23720 | 0.09210 | 0.0690* | |
H10 | −0.14620 | 0.52930 | 0.16190 | 0.0610* | |
H11 | 0.03440 | 0.59240 | 0.21080 | 0.0510* | |
H12 | 0.4567 (19) | 0.229 (3) | 0.5093 (14) | 0.060 (7)* | |
H13 | 0.3411 (17) | 0.224 (3) | 0.4844 (12) | 0.049 (6)* | |
H14 | 0.1179 (17) | −0.220 (3) | 0.1030 (13) | 0.048 (7)* | |
H15 | −0.001 (2) | −0.180 (3) | 0.0684 (15) | 0.076 (8)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.0266 (1) | 0.0335 (1) | 0.0333 (1) | −0.0016 (1) | 0.0141 (1) | −0.0003 (1) |
O1 | 0.0295 (7) | 0.0589 (9) | 0.0385 (7) | −0.0032 (6) | 0.0149 (6) | 0.0086 (6) |
O2 | 0.0307 (7) | 0.0327 (7) | 0.0541 (8) | 0.0009 (5) | 0.0203 (6) | −0.0001 (6) |
N1 | 0.0283 (7) | 0.0316 (8) | 0.0397 (8) | −0.0026 (6) | 0.0170 (6) | −0.0001 (7) |
N2 | 0.0427 (11) | 0.0594 (12) | 0.0359 (10) | −0.0036 (9) | 0.0164 (9) | 0.0035 (9) |
N3 | 0.0282 (7) | 0.0349 (9) | 0.0314 (7) | 0.0022 (6) | 0.0136 (6) | 0.0001 (7) |
N4 | 0.0430 (10) | 0.0347 (10) | 0.0493 (10) | 0.0040 (9) | 0.0154 (8) | −0.0012 (8) |
N5 | 0.0387 (9) | 0.0392 (10) | 0.0429 (9) | −0.0012 (7) | 0.0154 (8) | −0.0075 (8) |
N6 | 0.0427 (9) | 0.0333 (9) | 0.0391 (9) | 0.0023 (8) | 0.0206 (8) | −0.0010 (8) |
N7 | 0.0520 (12) | 0.0594 (12) | 0.0527 (11) | −0.0042 (9) | 0.0048 (9) | −0.0122 (10) |
N8 | 0.0602 (10) | 0.0388 (10) | 0.0398 (9) | −0.0011 (8) | 0.0290 (8) | −0.0004 (8) |
N9 | 0.0484 (9) | 0.0424 (10) | 0.0381 (9) | −0.0028 (8) | 0.0236 (8) | 0.0049 (9) |
N10 | 0.138 (2) | 0.0638 (14) | 0.0597 (13) | −0.0046 (14) | 0.0629 (15) | −0.0130 (11) |
C1 | 0.0309 (9) | 0.0304 (10) | 0.0373 (10) | −0.0016 (8) | 0.0145 (8) | −0.0022 (8) |
C2 | 0.0319 (10) | 0.0545 (13) | 0.0433 (11) | −0.0021 (9) | 0.0114 (9) | −0.0047 (10) |
C3 | 0.0271 (10) | 0.0607 (15) | 0.0608 (14) | 0.0003 (9) | 0.0147 (10) | −0.0090 (11) |
C4 | 0.0366 (10) | 0.0476 (12) | 0.0687 (14) | −0.0008 (10) | 0.0329 (10) | −0.0020 (11) |
C5 | 0.0390 (10) | 0.0381 (11) | 0.0501 (11) | −0.0008 (9) | 0.0274 (9) | 0.0006 (10) |
C6 | 0.0341 (10) | 0.0321 (11) | 0.0351 (10) | −0.0031 (8) | 0.0146 (8) | 0.0016 (8) |
C7 | 0.0283 (8) | 0.0435 (11) | 0.0275 (8) | 0.0007 (8) | 0.0121 (7) | 0.0025 (8) |
C8 | 0.0320 (10) | 0.0598 (13) | 0.0411 (10) | −0.0076 (10) | 0.0134 (8) | −0.0059 (10) |
C9 | 0.0258 (10) | 0.097 (2) | 0.0460 (12) | 0.0026 (11) | 0.0162 (9) | −0.0008 (12) |
C10 | 0.0369 (11) | 0.0722 (16) | 0.0451 (11) | 0.0160 (11) | 0.0214 (10) | 0.0006 (11) |
C11 | 0.0411 (10) | 0.0473 (12) | 0.0392 (10) | 0.0116 (9) | 0.0204 (9) | 0.0022 (9) |
C12 | 0.0360 (10) | 0.0320 (10) | 0.0317 (9) | 0.0003 (8) | 0.0157 (8) | 0.0024 (8) |
Ni1—O1 | 2.0701 (13) | N4—H14 | 0.80 (2) |
Ni1—O2 | 2.0941 (12) | N4—H15 | 0.94 (3) |
Ni1—N1 | 2.0685 (17) | C1—C6 | 1.502 (3) |
Ni1—N3 | 2.0559 (17) | C1—C2 | 1.378 (3) |
Ni1—N5 | 2.0652 (14) | C2—C3 | 1.381 (4) |
Ni1—N8 | 2.0863 (17) | C3—C4 | 1.364 (3) |
O1—C6 | 1.243 (2) | C4—C5 | 1.379 (3) |
O2—C12 | 1.234 (3) | C7—C8 | 1.376 (3) |
N1—C1 | 1.344 (2) | C7—C12 | 1.497 (3) |
N1—C5 | 1.339 (3) | C8—C9 | 1.386 (3) |
N2—C6 | 1.324 (3) | C9—C10 | 1.356 (4) |
N3—C7 | 1.344 (2) | C10—C11 | 1.382 (3) |
N3—C11 | 1.331 (3) | C2—H2 | 0.9300 |
N4—C12 | 1.328 (3) | C3—H3 | 0.9300 |
N5—N6 | 1.172 (2) | C4—H4 | 0.9300 |
N6—N7 | 1.163 (3) | C5—H5 | 0.9300 |
N8—N9 | 1.175 (2) | C8—H8 | 0.9300 |
N9—N10 | 1.159 (3) | C9—H9 | 0.9300 |
N2—H12 | 0.86 (3) | C10—H10 | 0.9300 |
N2—H13 | 0.85 (3) | C11—H11 | 0.9300 |
O1—Ni1—O2 | 93.30 (5) | C2—C1—C6 | 125.28 (17) |
O1—Ni1—N1 | 78.45 (6) | C1—C2—C3 | 118.6 (2) |
O1—Ni1—N3 | 89.76 (6) | C2—C3—C4 | 119.7 (2) |
O1—Ni1—N5 | 88.69 (6) | C3—C4—C5 | 118.8 (2) |
O1—Ni1—N8 | 175.91 (6) | N1—C5—C4 | 122.39 (18) |
O2—Ni1—N1 | 94.34 (6) | O1—C6—N2 | 121.6 (2) |
O2—Ni1—N3 | 78.08 (6) | N2—C6—C1 | 119.7 (2) |
O2—Ni1—N5 | 173.44 (7) | O1—C6—C1 | 118.71 (16) |
O2—Ni1—N8 | 89.94 (5) | C8—C7—C12 | 125.59 (18) |
N1—Ni1—N3 | 165.67 (6) | N3—C7—C12 | 112.41 (17) |
N1—Ni1—N5 | 92.18 (6) | N3—C7—C8 | 121.95 (19) |
N1—Ni1—N8 | 98.83 (7) | C7—C8—C9 | 118.6 (2) |
N3—Ni1—N5 | 95.69 (7) | C8—C9—C10 | 119.6 (2) |
N3—Ni1—N8 | 93.36 (7) | C9—C10—C11 | 118.9 (2) |
N5—Ni1—N8 | 88.36 (6) | N3—C11—C10 | 122.39 (19) |
Ni1—O1—C6 | 114.90 (13) | N4—C12—C7 | 117.8 (2) |
Ni1—O2—C12 | 114.68 (13) | O2—C12—N4 | 123.2 (2) |
Ni1—N1—C1 | 114.71 (14) | O2—C12—C7 | 119.01 (17) |
Ni1—N1—C5 | 126.71 (13) | C1—C2—H2 | 121.00 |
C1—N1—C5 | 118.28 (18) | C3—C2—H2 | 121.00 |
Ni1—N3—C7 | 115.52 (13) | C2—C3—H3 | 120.00 |
Ni1—N3—C11 | 125.88 (13) | C4—C3—H3 | 120.00 |
C7—N3—C11 | 118.55 (18) | C3—C4—H4 | 121.00 |
Ni1—N5—N6 | 123.67 (13) | C5—C4—H4 | 121.00 |
N5—N6—N7 | 178.2 (2) | N1—C5—H5 | 119.00 |
Ni1—N8—N9 | 122.99 (12) | C4—C5—H5 | 119.00 |
N8—N9—N10 | 176.9 (3) | C7—C8—H8 | 121.00 |
H12—N2—H13 | 119 (2) | C9—C8—H8 | 121.00 |
C6—N2—H12 | 122.0 (18) | C8—C9—H9 | 120.00 |
C6—N2—H13 | 119.4 (14) | C10—C9—H9 | 120.00 |
C12—N4—H14 | 116.3 (16) | C9—C10—H10 | 121.00 |
C12—N4—H15 | 123.0 (15) | C11—C10—H10 | 121.00 |
H14—N4—H15 | 119 (2) | N3—C11—H11 | 119.00 |
N1—C1—C2 | 122.2 (2) | C10—C11—H11 | 119.00 |
N1—C1—C6 | 112.46 (17) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H12···N7i | 0.86 (3) | 2.12 (2) | 2.967 (3) | 165 (3) |
N2—H13···N10ii | 0.85 (3) | 2.31 (3) | 3.154 (4) | 172 (2) |
N4—H14···N8iii | 0.80 (2) | 2.36 (2) | 3.136 (3) | 164 (2) |
N4—H15···N10iv | 0.94 (3) | 2.50 (3) | 3.442 (4) | 179 (3) |
C2—H2···N7i | 0.93 | 2.61 | 3.516 (3) | 163 |
C4—H4···O2v | 0.93 | 2.55 | 3.318 (3) | 140 |
C8—H8···N10iv | 0.93 | 2.37 | 3.297 (3) | 174 |
C10—H10···O1vi | 0.93 | 2.33 | 3.256 (3) | 172 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, −y+1/2, z+1/2; (iii) x, y−1, z; (iv) −x, −y, −z; (v) −x+1, y+1/2, −z+1/2; (vi) −x, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Ni(N3)2(C6H6N2O)2] |
Mr | 387.01 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 14.3438 (5), 6.6986 (2), 18.7969 (10) |
β (°) | 120.738 (3) |
V (Å3) | 1552.34 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.28 |
Crystal size (mm) | 0.22 × 0.18 × 0.05 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur diffractometer with Sapphire3 detector |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.815, 0.938 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15901, 4516, 2692 |
Rint | 0.034 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.068, 0.89 |
No. of reflections | 4516 |
No. of parameters | 242 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.43, −0.30 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Bruno et al., 2002), PLATON (Spek, 2003).
Ni1—O1 | 2.0701 (13) | Ni1—N3 | 2.0559 (17) |
Ni1—O2 | 2.0941 (12) | Ni1—N5 | 2.0652 (14) |
Ni1—N1 | 2.0685 (17) | Ni1—N8 | 2.0863 (17) |
O1—Ni1—O2 | 93.30 (5) | O2—Ni1—N8 | 89.94 (5) |
O1—Ni1—N1 | 78.45 (6) | N1—Ni1—N3 | 165.67 (6) |
O1—Ni1—N3 | 89.76 (6) | N1—Ni1—N5 | 92.18 (6) |
O1—Ni1—N5 | 88.69 (6) | N1—Ni1—N8 | 98.83 (7) |
O1—Ni1—N8 | 175.91 (6) | N3—Ni1—N5 | 95.69 (7) |
O2—Ni1—N1 | 94.34 (6) | N3—Ni1—N8 | 93.36 (7) |
O2—Ni1—N3 | 78.08 (6) | N5—Ni1—N8 | 88.36 (6) |
O2—Ni1—N5 | 173.44 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H12···N7i | 0.86 (3) | 2.12 (2) | 2.967 (3) | 165 (3) |
N2—H13···N10ii | 0.85 (3) | 2.31 (3) | 3.154 (4) | 172 (2) |
N4—H14···N8iii | 0.80 (2) | 2.36 (2) | 3.136 (3) | 164 (2) |
N4—H15···N10iv | 0.94 (3) | 2.50 (3) | 3.442 (4) | 179 (3) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, −y+1/2, z+1/2; (iii) x, y−1, z; (iv) −x, −y, −z. |
Acknowledgements
This research was supported by the Ministry of Science, Education and Sports of the Republic of Croatia, Zagreb (grant No. 119-1193079-1332).
References
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This research is a part of our wider interest of the structural role of azide ions and of its metal complexes in metabolic processes of mitohondria (Yuwen et al., 2000).
In the title compound NiIIatom lies in a general position and exhibits distorted octahedral environment (Fig. 1). The coordination sphere is composed by two cis-related N,O-chelating picolinamide and two azide ligands. The picolinamide ligands are bonded more tightly (Table 1) than in its trans-isomer (Đaković & Popović, 2007). All other bond lengths are comparable to the values reported for similar compounds (Allen et al., 1987). The azide ligands are coordinated to the central metal ion in non-linear mode (123.7 (1) and 123.0 (1)°) with the azide bond angles being 178.2 (2) and 176.9 (3)°.
The crystals of the title compound (I) are turquoise-green apart from the crystals of its trans-isomer which are olive-green.
The crystal structure (Fig 2) is stabilized by N—H···N hydrogen bond network between carboxamide groups and azide ligands. Typical amide N—H···O carboxamide dimers of R22(8) found in trans-isomer are not observed in the cis-isomer. Instead, the amide N atoms, N2 and N4, are involved in two hydrogen bonds, forming R22(16) rings, between two neighbouring molecules whereas C(8) chains along the axis c and C(6) chains along the axis b complete the network (Bernstein et al., 1995; Etter, 1990).
The slightly smaller density of (I), and the fact that it is formed first and then transformed into its trans-isomer, suggests that (I) is the thermodinamically less stable isomer.