Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270112046422/sk3457sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270112046422/sk3457Isup2.hkl |
CCDC reference: 915096
Potassium oxalate monohydrate (0.03 g, 0.16 mmol) was gradually added to a stirred solution of nickel(II) acetate tetrahydrate (0.2 g, 0.8 mmol) and 2-pyEtOH (0.2 ml, 1.8 mmol) in methanol (10 ml) at room temperature. Sodium methoxide (0.54 g, 1 mmol) was gradually added when the solution was heated to boiling point. The precipitate which formed was filtered off after 5 min of continuous stirring and heating. The remaining light-green solution was allowed to cool and was left to slowly evaporate under ambient conditions. Blue prismatic crystals were obtained from the green oil after a month.
All H atoms were initially found in a Fourier difference map, but were included in the final refinement cycles in calculated positions and refined as riding on their parent atoms. Aromatic H atoms were permitted to ride with C—H = 0.93 Å and Ueq(H) = 1.2UisoC, H atoms bonded to O atoms were permitted to ride with O—H = 0.82 Å and Ueq(H)=1.5iso(O), those of the CH2 groups with C—H = 0.97 Å and Ueq(H) = 1.2UisoC and those of the CH3 groups with C—H = 0.96 Å and Ueq(H) = 1.5UisoC.
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); 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); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and CrystalMaker (CrystalMaker, 2007).
[Ni(C2H3O2)2(C7H9NO)2] | F(000) = 444 |
Mr = 423.10 | Dx = 1.476 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2802 reflections |
a = 8.4292 (3) Å | θ = 2.8–30.4° |
b = 12.4129 (4) Å | µ = 1.06 mm−1 |
c = 12.0850 (4) Å | T = 150 K |
β = 131.175 (2)° | Prismatic, blue |
V = 951.76 (6) Å3 | 0.2 × 0.16 × 0.14 mm |
Z = 2 |
Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer | 2178 independent reflections |
Radiation source: SuperNova (Mo) X-ray Source | 1862 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.032 |
Detector resolution: 10.4933 pixels mm-1 | θmax = 27.5°, θmin = 2.8° |
ω scans | h = −10→10 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | k = −16→12 |
Tmin = 0.812, Tmax = 1.000 | l = −15→15 |
5104 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)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.075 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0263P)2 + 0.3819P] where P = (Fo2 + 2Fc2)/3 |
2178 reflections | (Δ/σ)max = 0.025 |
126 parameters | Δρmax = 0.32 e Å−3 |
0 restraints | Δρmin = −0.34 e Å−3 |
[Ni(C2H3O2)2(C7H9NO)2] | V = 951.76 (6) Å3 |
Mr = 423.10 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.4292 (3) Å | µ = 1.06 mm−1 |
b = 12.4129 (4) Å | T = 150 K |
c = 12.0850 (4) Å | 0.2 × 0.16 × 0.14 mm |
β = 131.175 (2)° |
Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer | 2178 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | 1862 reflections with I > 2σ(I) |
Tmin = 0.812, Tmax = 1.000 | Rint = 0.032 |
5104 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.075 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.32 e Å−3 |
2178 reflections | Δρmin = −0.34 e Å−3 |
126 parameters |
Experimental. Absorption correction: CrysAlis PRO, Agilent Technologies, Version 1.171.35.11 (release 16–05-2011 CrysAlis171. NET) (compiled May 16 2011,17:55:39) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | ||
Ni1 | 0.5000 | 0.0000 | 0.5000 | 0.01492 (11) | |
N11 | 0.2163 (2) | 0.04986 (13) | 0.29641 (15) | 0.0169 (3) | |
C12 | 0.1659 (3) | 0.15434 (15) | 0.25796 (18) | 0.0199 (4) | |
C13 | −0.0312 (3) | 0.18454 (16) | 0.12683 (19) | 0.0243 (4) | |
H13 | −0.0649 | 0.2570 | 0.1033 | 0.029* | |
C14 | −0.1762 (3) | 0.10616 (17) | 0.03208 (19) | 0.0259 (4) | |
H14 | −0.3069 | 0.1251 | −0.0568 | 0.031* | |
C15 | −0.1241 (3) | −0.00049 (16) | 0.0713 (2) | 0.0230 (4) | |
H15 | −0.2191 | −0.0547 | 0.0092 | 0.028* | |
C16 | 0.0709 (3) | −0.02575 (16) | 0.20397 (19) | 0.0200 (4) | |
H16 | 0.1039 | −0.0978 | 0.2310 | 0.024* | |
C2A | 0.3283 (3) | 0.23731 (15) | 0.36254 (19) | 0.0247 (4) | |
H2A | 0.2743 | 0.3081 | 0.3189 | 0.030* | |
H2B | 0.4538 | 0.2250 | 0.3761 | 0.030* | |
C1A | 0.3889 (3) | 0.23659 (15) | 0.51194 (19) | 0.0262 (4) | |
H12A | 0.4688 | 0.3011 | 0.5656 | 0.031* | |
H12B | 0.2623 | 0.2371 | 0.4987 | 0.031* | |
O1A | 0.51246 (19) | 0.14359 (10) | 0.59543 (13) | 0.0224 (3) | |
H1A | 0.4708 | 0.1178 | 0.6348 | 0.034* | |
O31 | 0.32257 (18) | −0.07155 (10) | 0.54228 (13) | 0.0200 (3) | |
O32 | 0.3705 (2) | 0.04846 (13) | 0.70003 (14) | 0.0315 (3) | |
C31 | 0.2984 (3) | −0.03858 (16) | 0.62914 (18) | 0.0211 (4) | |
C32 | 0.1691 (3) | −0.10893 (19) | 0.6463 (2) | 0.0298 (5) | |
H32A | 0.1755 | −0.0806 | 0.7231 | 0.045* | |
H32B | 0.2245 | −0.1809 | 0.6711 | 0.045* | |
H32C | 0.0252 | −0.1100 | 0.5556 | 0.045* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.01389 (17) | 0.01210 (17) | 0.01555 (17) | 0.00006 (11) | 0.00831 (14) | −0.00062 (11) |
N11 | 0.0166 (7) | 0.0153 (8) | 0.0184 (7) | 0.0005 (6) | 0.0113 (6) | 0.0015 (6) |
C12 | 0.0222 (9) | 0.0179 (10) | 0.0219 (8) | 0.0010 (7) | 0.0155 (8) | 0.0008 (7) |
C13 | 0.0269 (9) | 0.0221 (10) | 0.0213 (9) | 0.0071 (8) | 0.0148 (8) | 0.0046 (7) |
C14 | 0.0219 (9) | 0.0324 (12) | 0.0181 (8) | 0.0066 (8) | 0.0109 (8) | 0.0030 (8) |
C15 | 0.0189 (9) | 0.0260 (11) | 0.0198 (9) | −0.0036 (7) | 0.0109 (8) | −0.0048 (7) |
C16 | 0.0212 (9) | 0.0175 (9) | 0.0208 (9) | −0.0014 (7) | 0.0137 (8) | −0.0003 (7) |
C2A | 0.0229 (9) | 0.0130 (9) | 0.0306 (10) | 0.0004 (7) | 0.0143 (8) | 0.0029 (7) |
C1A | 0.0219 (9) | 0.0155 (10) | 0.0263 (9) | 0.0020 (7) | 0.0095 (8) | −0.0035 (7) |
O1A | 0.0234 (6) | 0.0155 (7) | 0.0226 (6) | 0.0013 (5) | 0.0127 (5) | −0.0012 (5) |
O31 | 0.0215 (6) | 0.0191 (7) | 0.0210 (6) | −0.0011 (5) | 0.0147 (5) | −0.0018 (5) |
O32 | 0.0364 (8) | 0.0336 (9) | 0.0282 (7) | −0.0057 (7) | 0.0229 (7) | −0.0104 (6) |
C31 | 0.0151 (8) | 0.0250 (10) | 0.0155 (8) | 0.0045 (7) | 0.0068 (7) | 0.0023 (7) |
C32 | 0.0313 (10) | 0.0368 (13) | 0.0295 (10) | −0.0001 (9) | 0.0236 (9) | 0.0019 (9) |
Ni1—O31i | 2.0719 (12) | C15—H15 | 0.9300 |
Ni1—O31 | 2.0719 (12) | C16—H16 | 0.9300 |
Ni1—O1A | 2.0877 (13) | C2A—C1A | 1.519 (3) |
Ni1—O1Ai | 2.0877 (13) | C2A—H2A | 0.9700 |
Ni1—N11i | 2.0996 (13) | C2A—H2B | 0.9700 |
Ni1—N11 | 2.0996 (13) | C1A—O1A | 1.432 (2) |
N11—C12 | 1.349 (2) | C1A—H12A | 0.9700 |
N11—C16 | 1.352 (2) | C1A—H12B | 0.9700 |
C12—C13 | 1.395 (2) | O1A—H1A | 0.8200 |
C12—C2A | 1.501 (2) | O31—C31 | 1.262 (2) |
C13—C14 | 1.381 (3) | O32—C31 | 1.259 (2) |
C13—H13 | 0.9300 | C31—C32 | 1.514 (3) |
C14—C15 | 1.377 (3) | C32—H32A | 0.9600 |
C14—H14 | 0.9300 | C32—H32B | 0.9600 |
C15—C16 | 1.379 (3) | C32—H32C | 0.9600 |
O31i—Ni1—O31 | 180.0 | C16—C15—H15 | 120.5 |
O31—Ni1—O1A | 90.67 (5) | N11—C16—C15 | 122.76 (18) |
O31i—Ni1—O1Ai | 90.67 (5) | N11—C16—H16 | 118.6 |
O31—Ni1—O1Ai | 89.33 (5) | C15—C16—H16 | 118.6 |
O31—Ni1—N11 | 87.99 (5) | C12—C2A—C1A | 113.79 (16) |
O31i—Ni1—N11i | 87.99 (5) | C12—C2A—H2A | 108.8 |
O31—Ni1—N11i | 92.01 (5) | C1A—C2A—H2A | 108.8 |
O1A—Ni1—N11 | 89.99 (5) | C12—C2A—H2B | 108.8 |
O1Ai—Ni1—N11i | 89.99 (5) | C1A—C2A—H2B | 108.8 |
O31i—Ni1—N11 | 92.01 (5) | H2A—C2A—H2B | 107.7 |
O31—Ni1—N11 | 87.99 (5) | O1A—C1A—C2A | 111.21 (15) |
O1Ai—Ni1—N11 | 90.01 (5) | O1A—C1A—H12A | 109.4 |
N11i—Ni1—N11 | 180.0 | C2A—C1A—H12A | 109.4 |
C12—N11—C16 | 118.32 (15) | O1A—C1A—H12B | 109.4 |
C12—N11—Ni1 | 123.00 (11) | C2A—C1A—H12B | 109.4 |
C16—N11—Ni1 | 118.50 (12) | H12A—C1A—H12B | 108.0 |
N11—C12—C13 | 121.28 (16) | C1A—O1A—H1A | 109.5 |
N11—C12—C2A | 117.64 (15) | C31—O31—Ni1 | 127.18 (12) |
C13—C12—C2A | 121.07 (17) | O32—C31—O31 | 125.02 (18) |
C14—C13—C12 | 119.63 (18) | O32—C31—C32 | 118.08 (17) |
C14—C13—H13 | 120.2 | O31—C31—C32 | 116.89 (17) |
C12—C13—H13 | 120.2 | C31—C32—H32A | 109.5 |
C15—C14—C13 | 118.97 (17) | C31—C32—H32B | 109.5 |
C15—C14—H14 | 120.5 | H32A—C32—H32B | 109.5 |
C13—C14—H14 | 120.5 | C31—C32—H32C | 109.5 |
C14—C15—C16 | 118.99 (17) | H32A—C32—H32C | 109.5 |
C14—C15—H15 | 120.5 | H32B—C32—H32C | 109.5 |
Symmetry code: (i) −x+1, −y, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1A—H1A···O31 | 0.82 | 2.55 | 2.9585 (18) | 112 |
O1A—H1A···O32 | 0.82 | 1.72 | 2.533 (2) | 172 |
Experimental details
Crystal data | |
Chemical formula | [Ni(C2H3O2)2(C7H9NO)2] |
Mr | 423.10 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 150 |
a, b, c (Å) | 8.4292 (3), 12.4129 (4), 12.0850 (4) |
β (°) | 131.175 (2) |
V (Å3) | 951.76 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.06 |
Crystal size (mm) | 0.2 × 0.16 × 0.14 |
Data collection | |
Diffractometer | Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2011) |
Tmin, Tmax | 0.812, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5104, 2178, 1862 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.075, 1.04 |
No. of reflections | 2178 |
No. of parameters | 126 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.32, −0.34 |
Computer programs: CrysAlis PRO (Agilent, 2011), SHELXS97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and CrystalMaker (CrystalMaker, 2007).
D—H···A | D—H | H···A | D···A | D—H···A |
O1A—H1A···O31 | 0.82 | 2.55 | 2.9585 (18) | 112 |
O1A—H1A···O32 | 0.82 | 1.72 | 2.533 (2) | 172 |
Polymorph A | Polymorph B | Polymorph C | |
Crystal system | Monoclinic | Triclinic | Monoclinic |
Space group | P21/c | P1 | P21/c |
Z | 4 | 2 | 4 |
a (Å) | 8.4777 (2) | 9.0784 (2) | 8.4292 (3) |
b (Å) | 7.9182 (2) | 9.8113 (2) | 12.4129 (4) |
c (°) | 15.1985 (3) | 12.3803 (2) | 12.0850 (4) |
α (°) | 100.8972 (12) | ||
β (°) | 104.983 (2) | 104.9007 (11) | 131.175 (2) |
γ (°) | 107.3424 (12) | ||
V (Å3) | 985.56 (4) | 974.09 (3) | 951.76 (6) |
Dcalc (Mg m-3) | 1.426 | 1.443 | 1.476 |
In order to retain the space group P21/c for comparison purposes, polymorph C is described using a nonreduced unit cell. The corresponding reduced cell is as follows: a = 8.4292 (3), b = 12.4129 (4), c = 9.1087 (3) Å and β = 92.976 (3)°. |
Polymorph A | |||
Ni1—N11 | 2.0905 (14) | O31—Ni1—N11 | 88.09 (5) |
Ni1—O1A | 2.1038 (12) | O31—Ni1—O1A | 90.90 (5) |
Ni1—O31 | 2.0643 (12) | O1A—Ni1—N11 | 88.93 (5) |
Polymorph B | |||
Ni1—N11 | 2.0955 (11) | O31—Ni1—N11 | 90.27 (4) |
Ni1—O1A | 2.0850 (9) | O31—Ni1—O1A | 90.03 (4) |
Ni1—O31 | 2.0644 (10) | O1A—Ni1—N11 | 89.93 (4) |
Ni2—N21 | 2.0833 (11) | O41—Ni2—N21 | 89.24 (4) |
Ni2—O1B | 2.0828 (10) | O41—Ni2—O1B | 89.71 (4) |
Ni2—O41 | 2.0798 (10) | O1B—Ni2—N21 | 89.68 (4) |
Polymorph C | |||
Ni1—N11 | 2.0996 (13) | O31—Ni1—N11 | 87.99 (5) |
Ni1—O1A | 2.0877 (13) | O31—Ni1—O1A | 90.67 (5) |
Ni1—O31 | 2.0719 (12) | O1A—Ni1—N11 | 89.99 (5) |
The synthesis of new metal–organic hybrid materials remains one of the major trends in the field of coordination chemistry and crystal engineering (Liu et al., 2010; Perry et al., 2009; Robin & Fromm, 2006; Schubert, 2011). The successful preparation of such materials requires suitable ligands with the ability to link the metal centres into larger architectures. Simple pyridine alcohols are versatile N,O-coordinating ligands capable of binding to metal ions in a variety of coordination modes: (i) monodentate through the pyridine N atom only; (ii) bidentate chelating through the pyridine N atom and the hydroxy O atom; and (iii) bidentate bridging with the hydroxy O atom as a bridge between two metal centres. We are interested in the coordination behaviour of simple pyridine alcohols in general (Lah et al., 2006, 2010; Lapanje et al., 2012) and 2-(pyridin-2-yl)ethanol (2-pyEtOH) is an example. A search of the Cambridge Structural Database (Allen, 2002) reveals 39 structures of different transition metals with 2-pyEtOH in its neutral form. Among these, six are NiII complexes, five of which are mononuclear with an octahedral arrangement of ligands around the central NiII atom and the 2-pyEtOH ligand coordinated in a chelating manner (Kong et al., 2009; Yilmaz et al., 2011; Hamamci et al., 2002; Yesilel et al., 2008; Lv et al., 2010). Additionally, a trinuclear NiII complex was reported in which the metal centres are connected by deprotonated 2-pyEtOH ligands, while an additional neutral 2-pyEtOH molecule acts as a terminal ligand and is coordinated to a single NiII atom in a chelating manner (Kayser et al., 2010). Recently, we have reported the structures of two polymorphs of bis(acetato-κO)bis[2-(pyridin-2-yl)ethanol-κ2N,O]nickel(II), (I), that concomitantly crystallize from a mixture of nickel acetate and 2-pyEtOH in acetonitrile, viz. a monoclinic and a triclinic form, which are referred to as polymorphs A and B, respectively (Trdin et al. 2012). Our work has recently been devoted to the preparation of new coordination polymers with the intention of replacing acetate ligands with other multifunctional organic ligands. During attempts to prepare NiII–oxalate complexes with 2-pyEtOH, light-blue crystals were obtained and subsequently identified as a third polymorph of mononuclear (I), herein denoted as polymorph C. The molecular structure is shown in Fig. 1. The NiII atom is located on an inversion centre and is surrounded by two 2-pyEtOH ligands coordinated in a chelating manner and by two acetate anions coordinated as monodentate ligands through one of the two carboxylate O atoms. Thus, an almost perfect octahedral N2O4 geometry is achieved. The noncoordinated carboxylate O atom enhances the stability of the complex through a strong intramolecular hydrogen bond with the hydroxy group of the 2-pyEtOH ligand [O32···O1A = 2.533 (2) Å; Table 1]. An additional attractive intramolecular interaction exists between the hydroxy group and the coordinated acetate O atom [O31···O1A = 2.9585 (18) Å]. It should be noted that the coordination geometry and the overall molecular structure, including the bifurcated intramolecular hydrogen bond, is similar in all three polymorphs. A comparison of the crystal data for all three polymorphs is given in Table 2 and selected geometric parameters are listed in Table 3.
The three polymorphs differ primarily in their packing arrangement, which is governed by weak intermolecular interactions. Polymorph C crystallizes in the monoclinic space group P21/c with two molecules in the unit cell. The packing is dominated by π–π stacking interactions between the pyridine rings of neighbouring molecules related by an inversion centre [centroid–centroid distance = 4.236 (12) Å, interplanar distance = 3.4720 (11) Å and offset angle = 34.95°]. The mononuclear units are connected via these interactions into infinite chains running parallel to the ac diagonal. The chains interact to form two-dimensional layers through weak contacts between the methyl groups and the noncoordinated O atom of the acetate groups protruding from the chains (Fig. 2a).
The other monoclinic polymorph, A, also crystallizes in the space group P21/c with a unit-cell volume of 33.80 Å3 larger than that of polymorph C [951.76 (6) Å3]. Differences in the intermolecular interactions are reflected in the arrangement of the molecules in space: no π–π interactions were observed, well separated molecules are distributed as shown in Fig. 2(b.
Triclinic polymorph B crystallizes in the space group P1 with a unit-cell volume of 11.5 Å3 smaller than that of polymorph A and 22.3 Å3 larger that that of polymorph C. The structure contains two crystallographically distinct molecules, both possessing an inversion centre. Thus, the asymmetric unit consists of two halves of the monomeric molecules. The molecules are arranged in two types of layers; each layer contains a set of crystallographycally equivalent molecules related by translation only (Fig. 2c). Molecules in the first type of layer (denoted a) are brought closer by π–π interactions of the same type as observed in polymorph C. Molecules in the second type of layer (denoted b) are oriented with respect to each other with the methyl groups of the acetate ligands. Additionally, C—H···π interactions [point-to-face edge-on T-shaped geometry; see Janiak (2000) for details] are observed.
In summary, for monomeric (I), three polymorphic phases are known. Two of them (polymorphs A and B) crystallize concomitantly from the mixture of NiII acetate and 2-pyEtOH in acetonitrile. The polymorphic form C crystallizes from the mixture of NiII acetate, 2-pyEtOH and potassium oxalate in methanol. The oxalate anion did not participate in the coordination to the NiII centre but, apparently, plays a templating role. Crystals of all three polymorphic forms are stable but have significantly different densities. The `density rule' (Bernstein, 2002), often used as an indicator of thermodynamic stability of different polymorphic forms, is not obeyed in this particular case. Recently, the synthesis and structure of a copper analogue was reported (Lapanje et al., 2012). Its structure is isomorphic with polymorph A. No polymorphism has been detected in the case of a copper compound.