metal-organic compounds
(2-Amino-7-methyl-4-oxidopteridine-6-carboxylato-κ3O4,N5,O6)(ethane-1,2-diamine-κ2N,N′)(1H-imidazole-κN3)nickel(II) dihydrate
aDepartment of Chemistry, University of North Bengal, Siliguri 734 013, India
*Correspondence e-mail: psrnbu@gmail.com
In the title complex, [Ni(C8H5N5O3)(C2H8N2)(C3N2H4)]·2H2O, a tridentate 2-amino-7-methyl-4-oxidopteridine-6-carboxylate (pterin) ligand, a bidentate ancillary ethane-1,2-diamine (en) ligand and a monodentate 1H-imidazole (im) ligand complete a distorted octahedral geometry around the NiII atom. The pterin ligand forms two chelate rings. Both the en and im ligands are arranged nearly orthogonally relative to the pterin ligand [dihedral angles between the mean planes of the en and pterin ligands and of the im and pterin ligands are 84.62 (9) and 85.14 (9)°, respectively]. N—H⋯N, N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the complex molecules and lattice water molecules into a three-dimensional network.
Related literature
For the importance of pterin in metalloenzymes, see: Basu & Burgmayer (2011); Burgmayer (1998); Fitzpatrick (2003); Fukuzumi & Kojima (2008); Kaim et al. (1999). For the structures of related nickel complexes, see: Baisya & Roy (2013); Crispini et al. (2005). For the structures of related copper complexes, see: Odani et al. (1992). For the electron-shuffling ability of the pterin unit as well as its donor groups and the effect on the geometric parameters of related complexes, see: Beddoes et al. (1993); Kohzuma et al. (1988); Russell et al. (1992). For the synthesis of the pterin ligand, see: Wittle et al. (1947). For of H atoms, see: Cooper et al. (2010).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS.
Supporting information
10.1107/S1600536813005898/hy2617sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536813005898/hy2617Isup2.hkl
2-Amino-4–hydroxy-7-methylpteridine-6-carboxylic acid sesquihydrate (C8H7N5O3.1.5H2O) was obtained by published procedure (Wittle et al., 1947). The title complex was synthesized by the dropwise addition of an aqueous alkaline solution (NaOH: 11 mg, 0.275 mmol) of the pterin ligand (31 mg, 0.125 mmol) to a warm (311 K; paraffin oil bath) aqueous reaction mixture containing NiSO4.7H2O (35 mg, 0.125 mmol), ethane-1,2-diamine (7.5 mg, 0.125 mmol) and 1H-imidazole (14 mg, 0.2 mmol); final volume was 45 ml. The pH value was adjusted to 10.3 and the mixture was stirred for 3 h; final pH was 9.7. The orange coloured solution was transferred to a 100 ml beaker and allowed to stand at room temperature. Orange crystals appeared after 4 days (yield: 40%), which were suitable for single-crystal X-ray diffraction. Sample for analytical purpose could be obtained by filtration, repeated washing with small quantities of water and drying in vacuo over silica gel. Analysis, calculated for C13H21N9NiO5: C 35.31, H 4.80, N 28.52%; found: C 35.72, H 4.70, N 28.07%.
The H atoms were all located in a difference map, but those attached to C atoms were repositioned geometrically. The H atoms were initially refined with soft restrains on bond lengths and angles to regularize their geometry (C—H = 0.93–0.98, N—H = 0.86–0.89, O—H = 0.82 Å) and Uiso(H) = 1.2–1.5Ueq(parent atom), after which the positions were refined with rigiding constrains (Cooper et al., 2010).
Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. | |
Fig. 2. The crystal packing diagram of the title compound, viewed along the a axis. Dotted lines indicate hydrogen bonds. |
[Ni(C8H5N5O3)(C2H8N2)(C3H4N2)]·2H2O | F(000) = 1840 |
Mr = 442.08 | Dx = 1.638 Mg m−3 |
Orthorhombic, Pbcn | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2n 2ab | Cell parameters from 4231 reflections |
a = 13.484 (2) Å | θ = 1.4–28.3° |
b = 8.8741 (15) Å | µ = 1.13 mm−1 |
c = 29.959 (5) Å | T = 293 K |
V = 3584.9 (10) Å3 | Plate, orange |
Z = 8 | 0.24 × 0.24 × 0.03 mm |
Bruker Kappa APEXII CCD diffractometer | 3521 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
ϕ and ω scans | θmax = 28.3°, θmin = 1.4° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −17→17 |
Tmin = 0.77, Tmax = 0.97 | k = −11→11 |
19640 measured reflections | l = −24→38 |
4231 independent reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.036 | H-atom parameters constrained |
wR(F2) = 0.091 | Method = Modified Sheldrick w = 1/[σ2(F2) + (0.04P)2 + 3.53P], where P = [max(Fo2,0) + 2Fc2]/3 |
S = 0.95 | (Δ/σ)max = 0.001 |
4231 reflections | Δρmax = 0.62 e Å−3 |
253 parameters | Δρmin = −0.32 e Å−3 |
0 restraints |
[Ni(C8H5N5O3)(C2H8N2)(C3H4N2)]·2H2O | V = 3584.9 (10) Å3 |
Mr = 442.08 | Z = 8 |
Orthorhombic, Pbcn | Mo Kα radiation |
a = 13.484 (2) Å | µ = 1.13 mm−1 |
b = 8.8741 (15) Å | T = 293 K |
c = 29.959 (5) Å | 0.24 × 0.24 × 0.03 mm |
Bruker Kappa APEXII CCD diffractometer | 4231 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 3521 reflections with I > 2σ(I) |
Tmin = 0.77, Tmax = 0.97 | Rint = 0.030 |
19640 measured reflections |
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.091 | H-atom parameters constrained |
S = 0.95 | Δρmax = 0.62 e Å−3 |
4231 reflections | Δρmin = −0.32 e Å−3 |
253 parameters |
x | y | z | Uiso*/Ueq | ||
Ni1 | 0.461327 (17) | 0.49322 (3) | 0.372395 (8) | 0.0275 | |
O1 | 0.54402 (10) | 0.60856 (16) | 0.32134 (5) | 0.0335 | |
C1 | 0.63525 (15) | 0.5742 (2) | 0.31846 (6) | 0.0292 | |
O2 | 0.69402 (11) | 0.62442 (18) | 0.29021 (5) | 0.0423 | |
C2 | 0.67092 (14) | 0.4597 (2) | 0.35277 (6) | 0.0262 | |
N1 | 0.59680 (11) | 0.40936 (17) | 0.37761 (5) | 0.0254 | |
C7 | 0.61252 (13) | 0.3066 (2) | 0.40867 (6) | 0.0252 | |
C4 | 0.70658 (13) | 0.2460 (2) | 0.41611 (6) | 0.0246 | |
N2 | 0.78491 (11) | 0.29914 (18) | 0.39231 (5) | 0.0286 | |
C3 | 0.76772 (14) | 0.4043 (2) | 0.36124 (6) | 0.0273 | |
C8 | 0.85670 (16) | 0.4622 (2) | 0.33676 (8) | 0.0407 | |
H111 | 0.9180 | 0.4284 | 0.3494 | 0.0629* | |
H113 | 0.8523 | 0.4298 | 0.3069 | 0.0630* | |
H112 | 0.8565 | 0.5676 | 0.3363 | 0.0619* | |
N3 | 0.71925 (12) | 0.13478 (18) | 0.44623 (5) | 0.0293 | |
C5 | 0.63537 (14) | 0.0864 (2) | 0.46626 (6) | 0.0297 | |
N4 | 0.54093 (12) | 0.14309 (19) | 0.46268 (5) | 0.0312 | |
C6 | 0.52732 (13) | 0.2575 (2) | 0.43450 (6) | 0.0268 | |
O3 | 0.44423 (10) | 0.32158 (16) | 0.42815 (5) | 0.0329 | |
N5 | 0.64372 (14) | −0.0319 (2) | 0.49338 (6) | 0.0414 | |
H172 | 0.5918 | −0.0634 | 0.5068 | 0.0504* | |
H171 | 0.7003 | −0.0668 | 0.4983 | 0.0503* | |
N6 | 0.32580 (14) | 0.6051 (2) | 0.36971 (7) | 0.0478 | |
C9 | 0.3190 (2) | 0.7106 (3) | 0.40720 (9) | 0.0610 | |
C10 | 0.4178 (2) | 0.7830 (3) | 0.41328 (10) | 0.0556 | |
N7 | 0.49397 (14) | 0.66577 (19) | 0.41780 (6) | 0.0367 | |
H211 | 0.5548 | 0.7039 | 0.4136 | 0.0564* | |
H212 | 0.4950 | 0.6335 | 0.4452 | 0.0559* | |
H202 | 0.4167 | 0.8476 | 0.4384 | 0.0688* | |
H201 | 0.4317 | 0.8402 | 0.3867 | 0.0695* | |
H192 | 0.2669 | 0.7839 | 0.4035 | 0.0736* | |
H191 | 0.3043 | 0.6540 | 0.4352 | 0.0746* | |
H181 | 0.2742 | 0.5434 | 0.3674 | 0.0732* | |
H182 | 0.3228 | 0.6546 | 0.3442 | 0.0727* | |
N8 | 0.41434 (14) | 0.3313 (2) | 0.32768 (6) | 0.0383 | |
C11 | 0.41880 (17) | 0.1814 (2) | 0.33182 (8) | 0.0416 | |
N9 | 0.38881 (18) | 0.1135 (3) | 0.29413 (9) | 0.0652 | |
C12 | 0.3599 (3) | 0.2243 (3) | 0.26639 (9) | 0.0699 | |
C13 | 0.3786 (3) | 0.3547 (3) | 0.28659 (9) | 0.0733 | |
H261 | 0.3671 | 0.4468 | 0.2743 | 0.0892* | |
H251 | 0.3344 | 0.2134 | 0.2406 | 0.0848* | |
H241 | 0.3806 | 0.0153 | 0.2892 | 0.0825* | |
H231 | 0.4395 | 0.1296 | 0.3568 | 0.0527* | |
O4 | 0.37876 (13) | 0.4892 (2) | 0.50415 (6) | 0.0543 | |
H271 | 0.3379 | 0.4436 | 0.5195 | 0.0824* | |
H272 | 0.3890 | 0.4340 | 0.4833 | 0.0825* | |
O5 | 0.38933 (16) | 0.7745 (2) | 0.28388 (6) | 0.0685 | |
H281 | 0.3645 | 0.7400 | 0.2605 | 0.1040* | |
H282 | 0.4446 | 0.7401 | 0.2817 | 0.1049* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.02605 (14) | 0.02545 (14) | 0.03107 (14) | 0.00016 (9) | −0.00317 (9) | 0.00076 (9) |
O1 | 0.0339 (7) | 0.0321 (7) | 0.0344 (7) | −0.0011 (6) | −0.0042 (6) | 0.0073 (6) |
C1 | 0.0361 (10) | 0.0262 (9) | 0.0253 (9) | −0.0028 (8) | −0.0023 (7) | 0.0001 (7) |
O2 | 0.0456 (9) | 0.0479 (9) | 0.0334 (7) | −0.0033 (7) | 0.0059 (6) | 0.0132 (7) |
C2 | 0.0310 (9) | 0.0226 (8) | 0.0250 (8) | −0.0023 (7) | 0.0013 (7) | −0.0009 (7) |
N1 | 0.0259 (7) | 0.0252 (8) | 0.0250 (7) | 0.0000 (6) | −0.0009 (6) | 0.0005 (6) |
C7 | 0.0274 (9) | 0.0237 (8) | 0.0245 (8) | −0.0002 (7) | 0.0010 (7) | −0.0007 (7) |
C4 | 0.0271 (9) | 0.0238 (8) | 0.0228 (8) | −0.0001 (7) | 0.0000 (7) | −0.0030 (7) |
N2 | 0.0280 (8) | 0.0257 (8) | 0.0320 (8) | 0.0009 (6) | 0.0034 (6) | −0.0004 (6) |
C3 | 0.0297 (10) | 0.0236 (8) | 0.0286 (9) | −0.0025 (7) | 0.0039 (7) | −0.0027 (7) |
C8 | 0.0323 (10) | 0.0358 (11) | 0.0541 (13) | 0.0004 (9) | 0.0119 (9) | 0.0109 (10) |
N3 | 0.0282 (8) | 0.0304 (8) | 0.0293 (8) | 0.0033 (6) | 0.0010 (6) | 0.0046 (6) |
C5 | 0.0340 (10) | 0.0275 (9) | 0.0275 (9) | 0.0017 (8) | 0.0013 (7) | 0.0023 (7) |
N4 | 0.0290 (8) | 0.0321 (8) | 0.0324 (8) | −0.0002 (6) | 0.0042 (6) | 0.0064 (7) |
C6 | 0.0263 (9) | 0.0281 (9) | 0.0258 (8) | −0.0016 (7) | 0.0007 (7) | −0.0003 (7) |
O3 | 0.0255 (6) | 0.0372 (7) | 0.0359 (7) | 0.0023 (6) | 0.0030 (5) | 0.0058 (6) |
N5 | 0.0376 (10) | 0.0412 (10) | 0.0454 (10) | 0.0058 (8) | 0.0078 (8) | 0.0188 (8) |
N6 | 0.0336 (10) | 0.0475 (11) | 0.0624 (13) | 0.0043 (8) | −0.0076 (9) | 0.0034 (9) |
C9 | 0.0523 (15) | 0.0690 (18) | 0.0617 (16) | 0.0258 (14) | 0.0095 (13) | 0.0033 (14) |
C10 | 0.0660 (17) | 0.0399 (13) | 0.0610 (16) | 0.0132 (12) | −0.0007 (13) | −0.0132 (11) |
N7 | 0.0413 (10) | 0.0360 (9) | 0.0329 (9) | −0.0008 (8) | −0.0013 (7) | −0.0027 (7) |
N8 | 0.0422 (10) | 0.0324 (9) | 0.0402 (9) | −0.0059 (8) | −0.0084 (8) | −0.0020 (7) |
C11 | 0.0428 (12) | 0.0323 (11) | 0.0498 (13) | −0.0009 (9) | −0.0073 (10) | −0.0025 (9) |
N9 | 0.0756 (16) | 0.0430 (12) | 0.0769 (16) | −0.0070 (11) | −0.0090 (13) | −0.0200 (11) |
C12 | 0.112 (3) | 0.0476 (15) | 0.0503 (15) | −0.0073 (16) | −0.0420 (16) | −0.0115 (12) |
C13 | 0.122 (3) | 0.0437 (14) | 0.0544 (16) | −0.0051 (16) | −0.0438 (17) | 0.0012 (12) |
O4 | 0.0545 (10) | 0.0558 (11) | 0.0525 (10) | −0.0125 (8) | 0.0175 (8) | −0.0034 (8) |
O5 | 0.0879 (14) | 0.0667 (12) | 0.0509 (10) | 0.0327 (11) | −0.0241 (10) | −0.0153 (9) |
Ni1—O1 | 2.1519 (14) | N5—H172 | 0.853 |
Ni1—N1 | 1.9787 (16) | N5—H171 | 0.837 |
Ni1—O3 | 2.2722 (14) | N6—C9 | 1.465 (3) |
Ni1—N6 | 2.0812 (19) | N6—H181 | 0.888 |
Ni1—N7 | 2.0949 (17) | N6—H182 | 0.881 |
Ni1—N8 | 2.0638 (17) | C9—C10 | 1.491 (4) |
O1—C1 | 1.270 (2) | C9—H192 | 0.964 |
C1—O2 | 1.242 (2) | C9—H191 | 0.997 |
C1—C2 | 1.523 (3) | C10—N7 | 1.468 (3) |
C2—N1 | 1.324 (2) | C10—H202 | 0.945 |
C2—C3 | 1.418 (3) | C10—H201 | 0.962 |
N1—C7 | 1.320 (2) | N7—H211 | 0.896 |
C7—C4 | 1.395 (2) | N7—H212 | 0.869 |
C7—C6 | 1.452 (2) | N8—C11 | 1.338 (3) |
C4—N2 | 1.359 (2) | N8—C13 | 1.338 (3) |
C4—N3 | 1.348 (2) | C11—N9 | 1.342 (3) |
N2—C3 | 1.338 (2) | C11—H231 | 0.922 |
C3—C8 | 1.497 (3) | N9—C12 | 1.346 (4) |
C8—H111 | 0.957 | N9—H241 | 0.890 |
C8—H113 | 0.940 | C12—C13 | 1.329 (4) |
C8—H112 | 0.936 | C12—H251 | 0.850 |
N3—C5 | 1.351 (2) | C13—H261 | 0.910 |
C5—N4 | 1.373 (2) | O4—H271 | 0.825 |
C5—N5 | 1.332 (2) | O4—H272 | 0.807 |
N4—C6 | 1.333 (2) | O5—H281 | 0.834 |
C6—O3 | 1.271 (2) | O5—H282 | 0.808 |
O1—Ni1—N1 | 75.91 (6) | C7—C6—O3 | 118.92 (16) |
O1—Ni1—O3 | 153.37 (5) | N4—C6—O3 | 123.85 (16) |
N1—Ni1—O3 | 77.50 (6) | Ni1—O3—C6 | 108.69 (11) |
O1—Ni1—N6 | 101.58 (7) | C5—N5—H172 | 118.4 |
N1—Ni1—N6 | 173.26 (7) | C5—N5—H171 | 118.4 |
O3—Ni1—N6 | 105.01 (7) | H172—N5—H171 | 122.9 |
O1—Ni1—N7 | 90.29 (6) | Ni1—N6—C9 | 109.29 (15) |
N1—Ni1—N7 | 91.70 (7) | Ni1—N6—H181 | 113.4 |
O3—Ni1—N7 | 91.95 (6) | C9—N6—H181 | 113.8 |
N6—Ni1—N7 | 82.01 (8) | Ni1—N6—H182 | 108.1 |
O1—Ni1—N8 | 91.65 (7) | C9—N6—H182 | 110.0 |
N1—Ni1—N8 | 94.18 (7) | H181—N6—H182 | 101.8 |
O3—Ni1—N8 | 88.82 (7) | N6—C9—C10 | 108.2 (2) |
N6—Ni1—N8 | 92.13 (8) | N6—C9—H192 | 112.9 |
N7—Ni1—N8 | 174.10 (7) | C10—C9—H192 | 112.0 |
Ni1—O1—C1 | 115.85 (12) | N6—C9—H191 | 109.6 |
O1—C1—O2 | 125.32 (18) | C10—C9—H191 | 107.0 |
O1—C1—C2 | 114.83 (16) | H192—C9—H191 | 107.0 |
O2—C1—C2 | 119.84 (17) | C9—C10—N7 | 109.3 (2) |
C1—C2—N1 | 111.47 (16) | C9—C10—H202 | 110.1 |
C1—C2—C3 | 130.01 (16) | N7—C10—H202 | 111.5 |
N1—C2—C3 | 118.51 (16) | C9—C10—H201 | 107.5 |
C2—N1—Ni1 | 121.72 (13) | N7—C10—H201 | 108.3 |
C2—N1—C7 | 120.55 (16) | H202—C10—H201 | 110.0 |
Ni1—N1—C7 | 117.63 (12) | C10—N7—Ni1 | 108.13 (14) |
N1—C7—C4 | 121.65 (16) | C10—N7—H211 | 111.1 |
N1—C7—C6 | 117.12 (16) | Ni1—N7—H211 | 112.2 |
C4—C7—C6 | 121.23 (16) | C10—N7—H212 | 109.4 |
C7—C4—N2 | 119.28 (16) | Ni1—N7—H212 | 112.0 |
C7—C4—N3 | 120.28 (16) | H211—N7—H212 | 104.0 |
N2—C4—N3 | 120.44 (16) | Ni1—N8—C11 | 128.20 (15) |
C4—N2—C3 | 118.19 (16) | Ni1—N8—C13 | 126.88 (17) |
C2—C3—N2 | 121.72 (16) | C11—N8—C13 | 104.8 (2) |
C2—C3—C8 | 122.07 (17) | N8—C11—N9 | 110.8 (2) |
N2—C3—C8 | 116.19 (17) | N8—C11—H231 | 125.8 |
C3—C8—H111 | 113.0 | N9—C11—H231 | 123.4 |
C3—C8—H113 | 108.0 | C11—N9—C12 | 106.2 (2) |
H111—C8—H113 | 109.6 | C11—N9—H241 | 128.0 |
C3—C8—H112 | 110.4 | C12—N9—H241 | 125.3 |
H111—C8—H112 | 108.7 | N9—C12—C13 | 107.5 (2) |
H113—C8—H112 | 107.0 | N9—C12—H251 | 126.4 |
C4—N3—C5 | 115.09 (15) | C13—C12—H251 | 126.1 |
N3—C5—N4 | 128.71 (17) | N8—C13—C12 | 110.6 (2) |
N3—C5—N5 | 116.80 (17) | N8—C13—H261 | 124.9 |
N4—C5—N5 | 114.49 (17) | C12—C13—H261 | 124.4 |
C5—N4—C6 | 117.14 (16) | H271—O4—H272 | 104.5 |
C7—C6—N4 | 117.19 (16) | H281—O5—H282 | 99.5 |
D—H···A | D—H | H···A | D···A | D—H···A |
N5—H171···O4i | 0.84 | 2.50 | 3.193 (3) | 140 |
N5—H172···N4ii | 0.85 | 2.13 | 2.984 (3) | 177 |
N6—H182···O5 | 0.88 | 2.28 | 3.099 (3) | 154 |
N7—H211···N2iii | 0.90 | 2.41 | 3.298 (2) | 173 |
N7—H212···O4iv | 0.87 | 2.53 | 3.210 (3) | 136 |
N9—H241···O5v | 0.89 | 2.15 | 3.024 (3) | 168 |
O4—H271···N3vi | 0.82 | 2.02 | 2.837 (2) | 169 |
O4—H272···O3 | 0.81 | 2.07 | 2.859 (2) | 167 |
O5—H281···O2vii | 0.83 | 2.00 | 2.822 (2) | 170 |
O5—H282···O1 | 0.81 | 2.14 | 2.789 (2) | 138 |
Symmetry codes: (i) x+1/2, −y+1/2, −z+1; (ii) −x+1, −y, −z+1; (iii) −x+3/2, y+1/2, z; (iv) −x+1, −y+1, −z+1; (v) x, y−1, z; (vi) x−1/2, −y+1/2, −z+1; (vii) −x+1, y, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Ni(C8H5N5O3)(C2H8N2)(C3H4N2)]·2H2O |
Mr | 442.08 |
Crystal system, space group | Orthorhombic, Pbcn |
Temperature (K) | 293 |
a, b, c (Å) | 13.484 (2), 8.8741 (15), 29.959 (5) |
V (Å3) | 3584.9 (10) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 1.13 |
Crystal size (mm) | 0.24 × 0.24 × 0.03 |
Data collection | |
Diffractometer | Bruker Kappa APEXII CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.77, 0.97 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19640, 4231, 3521 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.091, 0.95 |
No. of reflections | 4231 |
No. of parameters | 253 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.62, −0.32 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), CRYSTALS (Betteridge et al., 2003), CAMERON (Watkin et al., 1996).
D—H···A | D—H | H···A | D···A | D—H···A |
N5—H171···O4i | 0.84 | 2.50 | 3.193 (3) | 140 |
N5—H172···N4ii | 0.85 | 2.13 | 2.984 (3) | 177 |
N6—H182···O5 | 0.88 | 2.28 | 3.099 (3) | 154 |
N7—H211···N2iii | 0.90 | 2.41 | 3.298 (2) | 173 |
N7—H212···O4iv | 0.87 | 2.53 | 3.210 (3) | 136 |
N9—H241···O5v | 0.89 | 2.15 | 3.024 (3) | 168 |
O4—H271···N3vi | 0.82 | 2.02 | 2.837 (2) | 169 |
O4—H272···O3 | 0.81 | 2.07 | 2.859 (2) | 167 |
O5—H281···O2vii | 0.83 | 2.00 | 2.822 (2) | 170 |
O5—H282···O1 | 0.81 | 2.14 | 2.789 (2) | 138 |
Symmetry codes: (i) x+1/2, −y+1/2, −z+1; (ii) −x+1, −y, −z+1; (iii) −x+3/2, y+1/2, z; (iv) −x+1, −y+1, −z+1; (v) x, y−1, z; (vi) x−1/2, −y+1/2, −z+1; (vii) −x+1, y, −z+1/2. |
Acknowledgements
The authors are grateful to the UGC, New Delhi, for financial assistance (SAP–DRS program). Thanks are due to the CSMCRI, Bhavnagar, Gujrat, India, for the X-ray structural data and elemental analysis data, and the University of North Bengal for infrastructure.
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Increasing attention is being paid nowadays towards the metalloenzymes requiring both a pterin and a transition metal (Basu & Burgmayer, 2011; Burgmayer, 1998; Fitzpatrick, 2003; Fukuzumi & Kojima, 2008; Kaim et al., 1999). This has, in turn, catalysed research work on the coordination chemistry of the bicyclic N-heterocycles called pteridines in general, and an important member of this family named pterin in particular. Literature survey reveals the existence of only a couple of structurally characterized Ni(II)–pterin complexes (Baisya & Roy, 2013; Crispini et al., 2005) and no related quaternary complex. The present effort is concerned with the title quaternary complex, possessing a tridentate pterin ligand, a bidentate σ-donor ligand like en and a monodentate σ-donor ligand like im.
The molecular structure (Fig. 1) represents a mononuclear NiII centre in a distorted octahedral coordination geometry, with two N atoms (N6 and N7) of the en ligand, a pyrazine ring N atom (N1) of the pterin ligand and an imidazole ring N atom (N8), forming the equatorial plane. The two pterin O atoms (O1 and O3) occupy the longer axial positions, with the phenolate O3 constituting the longest axial bond [2.2722 (14) Å]. The pterin ligand forms two five-membered chelate rings having small bite angles [75.91 (6) and 77.50 (6)°], instead of only one per pterin ligand for an earlier case (Crispini et al., 2005). This factor is responsible to a large extent for the observed distortion here from regular octahedral geometry. Accordingly, the O1—Ni1—O3 axis shows maximum deviation [153.37 (5)°] from linearity. Again, closest approach to linearity [174.10 (7)°] is observed for the N7—Ni1—N8 axis, which is associated with both the im and en ligands. Here each such ligand tries to achieve near orthogonality with respect to the pterin ligand [dihedral angles between the mean planes of the en and pterin ligands and of the im and pterin ligands are 84.62 (9) and 85.14 (9)°, respectively], for minimizing the steric repulsion. In line with the earlier observations on related copper complexes (Odani et al., 1992), the pyrazine ring N atom (N1) is located in the equatorial plane. The corresponding short Ni1—N1 distance [1.9787 (16) Å] indicates dπ–pπ interaction between the pterin ring and the NiII atom (d8), with further assistance from the nearby π-donating phenolate and carboxylate O atoms (Kohzuma et al., 1988). The pterin ligand is coordinated in its binegative form as an O,N,O-donor, as evident from the charge balance of this Ni(II) complex. The significantly shorter nature of the O3—C6 [1.271 (2) Å] and N5—C5 [1.332 (2) Å] bonds could be rationalized in terms of electron-shuffling ability of the pterin ring (Baisya & Roy, 2013; Beddoes et al., 1993; Russell et al., 1992).
In the crystal, intermolecular N—H···N, N—H···O, O—H···N and O—H···O hydrogen bonds (Table 1) link the complex molecules and lattice water molecules into a three-dimensional network (Fig 2). The lattice water molecules play a decisive role for the crystal packing.