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Stabilization of an elusive tautomer by metal coordination
aDipartimento di Scienze Chimiche, Università degli Studi di Napoli 'Federico II', Complesso di Monte S. Angelo, Via Cinthia, 80126 Napoli, Italy
*Correspondence e-mail: roberto.centore@unina.it
The solid-state isolation of the different tautomers of a chemical compound can be a challenging problem. In many cases, tautomers with an energy very close to the most stable one cannot be isolated (elusive tautomers). In this article, with reference to the 4-methyl-7-(pyrazin-2-yl)-2H-[1,2,4]triazolo[3,2-c][1,2,4]triazole ligand, for which the elusive 3H-tautomer has an energy only 1.4 kcal mol−1 greater than the most stable 2H form, we show that metal complexation is a successful and reliable way for stabilizing the elusive tautomer. We have prepared two complexes of the neutral ligand with CuBr2 and ZnBr2, namely, aquabromidobis[4-methyl-7-(pyrazin-2-yl)-3H-[1,2,4]triazolo[3,2-c][1,2,4]triazole]copper(II) bromide trihydrate, [CuBr(C8H7N7)2(H2O)]Br·3H2O, and dibromido[4-methyl-7-(pyrazin-2-yl)-2H-[1,2,4]triazolo[3,2-c][1,2,4]triazole][4-methyl-7-(pyrazin-2-yl)-3H-[1,2,4]triazolo[3,2-c][1,2,4]triazole]zinc(II) monohydrate, [ZnBr2(C8H7N7)2]·H2O. The X-ray analysis shows that, in both cases, the elusive 3H-tautomer is present. The results of the crystallographic analysis of the two complexes reflect the different coordination preferences of CuII and ZnII. The copper(II) complex is homotautomeric as it only contains the elusive 3H-tautomer of the ligand. The complex can be described as octahedral with tetragonal distortion. Two 3H-triazolotriazole ligands are bis-chelated in the equatorial plane, while a water molecule and a bromide ion in elongated axial positions complete the coordination environment. The zinc(II) complex, on the other hand, is heterotautomeric and contains two bromide ions and two monodentate ligand molecules, one in the 2H-tautomeric form and the other in the 3H-tautomeric form, both coordinated to the metal in tetrahedral geometry. The observation of mixed-tautomer complexes is unprecedented for neutral ligands. The analysis of the X-ray molecular structures of the two complexes allows the deduction of possible rules for a rational design of mixed-tautomer complexes.
Keywords: heterocycle; triazole; tautomerism; elusive tautomer; crystal structure; zinc; copper.
1. Introduction
Tautomers are structural isomers in ready equilibrium between each other (McNaught & Wilkinson, 1997). They are intriguing chemical systems that, in a certain sense, can be considered as `living molecules'. In fact, because of the equilibrium they undergo, the relative amounts of the different forms in solution can be altered by physical or chemical factors (temperature, solvent, pH, metal ions, etc.) through the laws of Tautomers have been central in chemistry since the early work of Berzelius on cyanic and cyanuric acids in 1832, and the discovery of keto–enol by Erlenmeyer in 1880 (Taylor et al., 2014
). The issue of has been fundamental in many turning points of research in chemistry. For instance, it was fundamental in the discovery of the structure of DNA by Watson & Crick (1953a
), which relies on the keto-tautomeric forms of purine and and in their seminal hypothesis (Watson & Crick, 1953b
) that noncanonical tautomeric forms of the bases could be involved in mutagenesis (Goodman, 1995
; Wang et al., 2011
). Now the relevance of tautomers is increasingly recognized in many fields of applied chemistry, including drug design (Martin, 2009
) and materials chemistry (Bussetti et al., 2014
; Horiuchi et al., 2017
). In the realm of coordination chemistry, can also be a relevant issue, because some classes of ligands show As an example, keto–enol is shown in amino–naphthol derivatives (Deneva et al., 2019
), in dihydroxyquinolines (Todorov et al., 2012
) and in aroylhydrazine ligands (Borbone et al., 2004
), while thione–thiol is present in dithiocarbazate ligands (Takjoo & Centore, 2013
). In most of these cases, the common feature is that only one tautomeric form acts as the ligand and is found in the complexes.
In the realm of fused-ring heteroaromatic systems that we have studied over the years (Centore et al., 1996, 1999
; Ambrosanio et al., 1999
), we have found in [1,2,4]triazolo[3,2-c][1,2,4]triazole a heterocyclic system with a rich tautomeric behaviour (Centore et al., 2013
, 2015
, 2017
; Fusco et al., 2018
).
We have found that the relative energy of the three tautomers of the neutral molecule (Fig. 1) can be significantly modulated by acting on the electronic character of the substituents and on the polarity of the solvent. In all the cases investigated, the energy trend of the tautomers is E(2H) < E(3H) << E(5H); in particular, while the predicted energy of the 5H-tautomer is always prohibitive (+10.8 kcal mol−1 with respect to the 2H-tautomer, in the most favourable case) (Centore et al., 2015
), the calculated energy of the 3H-tautomer, in some cases, is greater than for the 2H-tautomer by only 1 kcal mol−1 or less (Centore et al., 2015
). Despite this, the 3H-tautomer should be considered elusive, because it has not yet been observed in the solid state for any of the pure triazolotriazole compounds studied so far.
![]() | Figure 1 Relevant chemical diagrams for the [1,2,4]triazolo[3,2-c][1,2,4]triazole system: the three tautomers of the neutral form (the adopted atom numbering of the heterobicycle is indicated only for the 2H-tautomer). |
We have recently described a new versatile nitrogen-rich triazolotriazole ligand, 4-methyl-7-(pyrazin-2-yl)-2H,3H-[1,2,4]triazolo[3,2-c][1,2,4]triazole, henceforth TT9 (Fig. 2a), whose tautomeric behaviour is further enriched by the possibility of metal coordination (Parisi et al., 2020
).
![]() | Figure 2 (a) Chemical diagram of the triazolotriazole ligand TT9 discussed in this article (the 2H-tautomer is shown). (b) The chemical formulae of the complexes studied in this article. |
In particular, while crystallization of the pure neutral ligand yielded the most stable 2H-tautomer, as expected, crystallization of neutral TT9 in the presence of ZnII and CuII salts yielded metal complexes of the neutral ligand, with a 1:1 metal-to-ligand ratio, in which the 3H-tautomer is present (Parisi et al., 2020). In order to further confirm metal complexation as a way of stabilizing the elusive 3H-tautomer, we report, in this article, structural data for the ZnII and CuII complexes of TT9, with a 1:2 metal-to-ligand ratio (Fig. 2
b).
2. Experimental
All reagents were of analytical grade and were used without further purification.
2.1. Synthesis and crystallization
The synthesis of the TT9 ligand was performed according to the procedure already described by us (Parisi et al., 2020). Prismatic green crystals of the complex Cu(TT9)2Br2·3H2O, henceforth complex 1, were grown in 2 d by slow evaporation of a clear 50:50 (v/v) water–ethanol solution containing a 1:2 molar ratio of CuBr2 dihydrate (13.0 mg, 7.63 × 10−5 mol) and TT9 (31.0 mg, 1.56 × 10−4 mol) at room temperature in a quantitative yield (53.0 mg). Prismatic brown crystals of the complex Zn(TT9)2Br2·H2O, henceforth complex 2, were grown in a week by slow evaporation of a 50:50 (v/v) water–ethanol solution containing a 1:2 molar ratio of ZnBr2 (14 mg, 0.1 mmol) and TT9 (40 mg, 0.2 mmol) at room temperature in a 75% yield (48 mg).
2.2. Refinement
Crystal data, data collection and structure . H atoms bonded to C atoms were generated stereochemically and refined by the riding model. After having placed C-bound H atoms, those bonded to O and N atoms, that are essential in the identification of tautomers, were clearly found in difference Fourier maps as the first maxima and, in some cases, their coordinates were refined. For all H atoms, Uiso(H) = 1.2Ueq of the was assumed (1.5 in the case of methyl groups). The structure of complex 1, in the noncentrosymmetric Cc, was refined as a two-component inversion twin.
|
3. Results and discussion
The X-ray molecular structure of complex 1 is shown in Fig. 3. Two 3H-tautomeric s–cis TT9 neutral ligands are coordinated to copper(II) as bidentate chelates (N1 and N6) in a square-planar arrangement, with the formation of pentatomic chelate rings. The four metal-to-ligand distances in the equatorial plane show a clear and significant asymmetry. In fact, the bond lengths with N-pyrazinic donors [Cu—N6A = 2.117 (5) and Cu—N6B = 2.125 (5) Å] are longer than with N-triazole donors [Cu—N1A = 1.953 (5) and Cu—N1B = 1.951 (5) Å]. This presumably reflects the fact that the pyrazine N atom is a poorer donor. One water molecule and one bromide ion complete the coordination environment of CuII, with trans-elongated bond lengths of Cu—O = 2.410 (5) and Cu—Br = 2.7466 (12) Å. The coordination geometry can be described as octahedral with tetragonal distortion. The observed coordination geometry is typical of CuII and can be related to Jahn–Teller distortions (Cotton et al., 1999
).
![]() | Figure 3 The molecular structure of complex 1, with displacement ellipsoids drawn at the 30% probability level. Selected hydrogen bonds are indicated by dashed lines. |
The selection of the 3H-tautomer, in complex 1, is probably related to the strong preference of CuII for square-planar coordination with N-donor atoms. The formation of pentatomic (N1 and N6) chelate rings drives the selection of the s–cis conformer and the switching of the proton from N2 to N3. In fact, in the observed molecular structure, there are close intramolecular contacts (weak hydrogen bonds) C2A—H2A⋯N2B and C4B—H4B⋯N2A (Table 2). Three uncoordinated water molecules and a bromide ion are also present in the crystallographically independent unit. They are involved in strong hydrogen bonds with the N—H donors and N-atom acceptors present on the rim of the coordinated ligands (Table 2
).
|
The X-ray molecular structure of complex 2, shown in Fig. 4, has completely different features. The coordination around ZnII is basically tetrahedral and is accomplished through two bromide ions [Zn—Br1 2.4017 (11) and Zn—Br2 2.3581 (9) Å] and two TT9 ligands acting in a monodentate manner [Zn—N3A = 2.059 (4) and Zn—N2B = 2.018 (4) Å]. The two TT9 ligands are present in different tautomer/conformers. Ligand A is 2H-tautomeric s–trans, whereas ligand B is 3H-tautomeric s–cis. In the complex, the two ligands are hydrogen bonded to each other through a strong bifurcated hydrogen bond, N2A—H2NA⋯N1B and N2A—H2NA⋯N6B (Table 3
). Examples of complexes in which two different tautomeric forms of the same ligand are coordinated to the same metal centre are rare for anionic ligands (Sutradhar et al., 2016
), and, to the best of our knowledge, not previously documented for neutral ligands.
|
![]() | Figure 4 The molecular structure of complex 2, with displacement ellipsoids drawn at the 30% probability level. Selected hydrogen bonds are indicated by dashed lines. |
A deep inspection of the structure of complex 2 can suggest some basic points for the rational design of such mixed-tautomeric-ligand complexes. The two tautomeric forms should have similar ligand-donor capability and similar energy, in such a way that both are present in solution in similar amounts. They should possess complementary functional groups to form stable adducts by secondary interactions (e.g. hydrogen bonds), with a strong preference for mixed adducts. Finally, the mixed hydrogen-bonded adduct should be featured with a pocket, suitable for the dimensions and presence of donor atoms, to bind a metal ion. The fulfilment of all these issues may account for the rarity of the phenomenon.
The tautomeric/conformational variability of the TT9 ligand, which possesses four different tautomers/conformers within a narrow energy range ΔE < 2 kcal mol−1 (Parisi et al., 2020), makes TT9 a reliable candidate for this target. In fact, we have considered the formation of hydrogen-bonded dimers for the four lowest-energy tautomers/conformers of TT9, shown in Fig. 5
(Parisi et al., 2020
). Our analysis showed that, of the ten possible combinations, only in four cases can hydrogen-bonded dimers be formed, and they are shown in Fig. 6
. In all the dimers, a strong (bifurcated) hydrogen bond is present between the N—H donor of a tautomer and the two s–cis N-acceptor atoms of the other. The hydrogen-bonded dimers also show a pocket with two N-donor atoms that could host a metal ion, for instance, in tetrahedral coordination geometry. Of the four possible dimers, two are homotautomeric and contain the higher-energy 3H-tautomer, while the other two are heterotautomeric and contain both 2H- and 3H-tautomers. Evidently, the two latter, 2H s–trans/3H s–cis and 2H s–cis/3H s–cis, are energetically more feasible and their energies should be very close, within 0.1 kcal mol−1. Thus, our analysis confirms that the formation of mixed-tautomer complexes can be expected with TT9.
![]() | Figure 5 Low-energy tautomers/conformers of TT9. Relative energies are taken from Parisi et al. (2020 ![]() |
![]() | Figure 6 Hydrogen-bonded dimers of neutral TT9. The presence of a metal atom M in a tetrahedral coordination is also outlined. Highlighted in blue is the dimer found in complex 2. |
3.1. Supramolecular features
The crystal packing of both complexes is basically driven by the formation of a network of strong hydrogen bonds involving N—H donors and N-atom acceptors of the ligand molecules, the bromide ions and the water molecules (see Tables 2 and 3
).
The equatorial plane of complex 1 is neither perpendicular nor parallel to the unique b axis. Therefore, in the crystal, molecules with two different orientations are present. The most remarkable supramolecular architecture is represented by hydrogen-bonded chains running along a−b and a+b (Fig. 7); these directions are equivalent by symmetry in the monoclinic system through the c-glide operation perpendicular to the unique b axis. The chains are formed by hydrogen bonding between water donors and bromide acceptors axially coordinated to the metal in consecutive complex molecules along the chains. Different chains are held together laterally by hydrogen bonds involving noncoordinated water molecules.
![]() | Figure 7 Partial crystal packing of complex 1. Selected hydrogen bonds are indicated by dashed lines. |
In complex 2, an intramolecular bifurcated hydrogen-bonding interaction is present between the N2A—H2NA donor group and the N1B and N6B acceptors of the two coordinated ligands. The most remarkable supramolecular architecture is represented by nearly planar hydrogen-bonded ribbons of molecules, running along a–b. The ribbons contain 2H-tautomeric s–trans and 3H-tautomeric s–cis ligand molecules intercalated by water molecules (Fig. 8).
![]() | Figure 8 Partial crystal packing of complex 2. Selected hydrogen bonds are indicated by dashed lines. |
4. Conclusions
Nitrogen-rich ligand TT9, i.e. 4-methyl-7-(pyrazin-2-yl)-2H-[1,2,4]triazolo[3,2-c][1,2,4]triazole, has a low-energy 3H-tautomer. While crystallization of pure TT9 from different solvents only affords the most stable 2H-tautomer, we have proven that metal coordination allows selection of the elusive 3H-tautomer. Depending on the stoichiometry of the complex, and on the metal, complexes with only the 3H-tautomeric ligand (homotautomeric), or complexes with mixed-tautomer ligands, i.e. both 2H and 3H (heterotautomeric), can be obtained.
Steering and selectively controlling the formation of the different energetically feasible tautomers of a given compound, depending on the physico-chemical environment, is of practical and theoretical relevance. In fact, different tautomers generally interact differently with the same substrate and show different properties: in an analogy with language, they have different `meaning'. After all, chemistry can be considered a language: atoms are its letters and molecules its words. Continuing with this analogy, tautomers, and more generally isomers, would correspond to the anagrams of ordinary language. In this analogy, the heterotautomeric complex 2 would correspond to a sentence containing two anagrams of the same word, e.g. `she married an admirer'.
This is uncommon also in ordinary language.
Supporting information
https://doi.org/10.1107/S2053229621006203/jx3062sup1.cif
contains datablocks global, 1, 2. DOI:Structure factors: contains datablock 1. DOI: https://doi.org/10.1107/S2053229621006203/jx30621sup2.hkl
Structure factors: contains datablock 2. DOI: https://doi.org/10.1107/S2053229621006203/jx30622sup3.hkl
For both structures, data collection: COLLECT (Nonius, 1999); cell
DIRAX/LSQ (Duisenberg et al., 2000); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2020); software used to prepare material for publication: WinGX (Farrugia, 2012).[CuBr(C8H7N7)2(H2O)]Br·3H2O | F(000) = 1388 |
Mr = 697.83 | Dx = 1.829 Mg m−3 |
Monoclinic, Cc | Mo Kα radiation, λ = 0.71073 Å |
a = 11.062 (4) Å | Cell parameters from 320 reflections |
b = 8.369 (3) Å | θ = 3.3–28.5° |
c = 27.406 (6) Å | µ = 4.07 mm−1 |
β = 92.44 (3)° | T = 173 K |
V = 2534.9 (14) Å3 | Prismatic, green |
Z = 4 | 0.50 × 0.20 × 0.20 mm |
Bruker–Nonius KappaCCD diffractometer | 4870 independent reflections |
Radiation source: normal-focus sealed tube | 4563 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
Detector resolution: 9 pixels mm-1 | θmax = 27.6°, θmin = 3.1° |
CCD rotation images, thick slices scans | h = −13→14 |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | k = −10→10 |
Tmin = 0.250, Tmax = 0.478 | l = −35→35 |
8682 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: mixed |
R[F2 > 2σ(F2)] = 0.033 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.081 | w = 1/[σ2(Fo2) + (0.0413P)2 + 2.1083P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
4870 reflections | Δρmax = 0.60 e Å−3 |
367 parameters | Δρmin = −0.86 e Å−3 |
13 restraints | Absolute structure: Refined as an inversion twin. |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.502 (12) |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Refined as a 2-component inversion twin. Data were collected on a Bruker-Nonius KappaCCD diffractometer equipped with Oxford Cryostream 700 apparatus. The structures were solved by direct methods and refined by the full matrix least squares method with anisotropic displacement parameters for non-H atoms. |
x | y | z | Uiso*/Ueq | ||
C1A | 0.2108 (5) | 0.3482 (7) | 0.1008 (2) | 0.0171 (11) | |
C2A | 0.0988 (5) | 0.1833 (7) | 0.0494 (2) | 0.0203 (12) | |
H2A | 0.055550 | 0.163375 | 0.019347 | 0.024* | |
C3A | 0.1070 (6) | 0.0641 (7) | 0.0854 (2) | 0.0233 (12) | |
H3A | 0.070052 | −0.036484 | 0.078759 | 0.028* | |
C4A | 0.2180 (6) | 0.2281 (7) | 0.1359 (2) | 0.0218 (12) | |
H4A | 0.261924 | 0.247106 | 0.165862 | 0.026* | |
C5A | 0.2645 (5) | 0.5042 (7) | 0.1058 (2) | 0.0164 (11) | |
C6A | 0.3529 (5) | 0.7240 (7) | 0.1263 (2) | 0.0177 (11) | |
C7A | 0.4323 (6) | 0.6809 (8) | 0.1994 (2) | 0.0227 (12) | |
C8A | 0.5012 (7) | 0.7127 (9) | 0.2462 (2) | 0.0322 (15) | |
H8A | 0.448925 | 0.767907 | 0.268770 | 0.048* | |
H8B | 0.571526 | 0.779821 | 0.240018 | 0.048* | |
H8C | 0.528625 | 0.611249 | 0.260743 | 0.048* | |
N1A | 0.2503 (5) | 0.6096 (6) | 0.07033 (17) | 0.0184 (10) | |
N2A | 0.3066 (5) | 0.7527 (6) | 0.08205 (18) | 0.0195 (10) | |
N3A | 0.4212 (5) | 0.7944 (6) | 0.16306 (18) | 0.0195 (10) | |
H3NA | 0.461 (6) | 0.882 (5) | 0.162 (3) | 0.023* | |
N4A | 0.3787 (5) | 0.5451 (6) | 0.18878 (17) | 0.0219 (10) | |
N5A | 0.3309 (4) | 0.5749 (6) | 0.14234 (16) | 0.0160 (9) | |
N6A | 0.1518 (4) | 0.3249 (5) | 0.05743 (18) | 0.0180 (10) | |
N7A | 0.1644 (5) | 0.0863 (6) | 0.12843 (18) | 0.0226 (11) | |
C1B | 0.1316 (5) | 0.6931 (7) | −0.0809 (2) | 0.0184 (11) | |
C2B | 0.1366 (6) | 0.7999 (7) | −0.1188 (2) | 0.0212 (12) | |
H2B | 0.101996 | 0.771551 | −0.149940 | 0.025* | |
C3B | 0.2360 (6) | 0.9747 (8) | −0.0686 (2) | 0.0252 (13) | |
H3B | 0.272402 | 1.076143 | −0.062860 | 0.030* | |
C4B | 0.2340 (6) | 0.8649 (7) | −0.0299 (2) | 0.0214 (12) | |
H4B | 0.270875 | 0.891593 | 0.000938 | 0.026* | |
C5B | 0.0785 (6) | 0.5357 (7) | −0.0844 (2) | 0.0190 (12) | |
C6B | −0.0024 (5) | 0.3091 (7) | −0.1041 (2) | 0.0191 (11) | |
C7B | −0.0630 (6) | 0.3334 (7) | −0.1805 (2) | 0.0236 (12) | |
C8B | −0.1181 (7) | 0.2884 (9) | −0.2287 (2) | 0.0335 (16) | |
H8D | −0.123800 | 0.382944 | −0.249744 | 0.050* | |
H8E | −0.199277 | 0.244961 | −0.224433 | 0.050* | |
H8F | −0.067814 | 0.207352 | −0.243794 | 0.050* | |
N1B | 0.0837 (4) | 0.4380 (6) | −0.04658 (18) | 0.0191 (10) | |
N2B | 0.0320 (5) | 0.2912 (6) | −0.05801 (18) | 0.0209 (10) | |
N3B | −0.0583 (5) | 0.2296 (6) | −0.14155 (18) | 0.0214 (10) | |
H3NB | −0.088 (6) | 0.137 (5) | −0.137 (3) | 0.026* | |
N4B | −0.0137 (5) | 0.4731 (6) | −0.17061 (17) | 0.0206 (11) | |
N5B | 0.0225 (4) | 0.4554 (6) | −0.12167 (17) | 0.0182 (10) | |
N6B | 0.1811 (4) | 0.7247 (6) | −0.03631 (17) | 0.0160 (9) | |
N7B | 0.1890 (5) | 0.9421 (6) | −0.1129 (2) | 0.0267 (12) | |
O1 | 0.3589 (5) | 0.4611 (5) | −0.01555 (18) | 0.0310 (10) | |
H1W | 0.381 (8) | 0.372 (5) | −0.005 (2) | 0.037* | |
H2W | 0.362 (7) | 0.449 (8) | −0.0455 (10) | 0.037* | |
O2 | 0.5055 (6) | 1.0913 (6) | 0.15962 (18) | 0.0420 (13) | |
H3W | 0.492 (9) | 1.114 (11) | 0.1310 (13) | 0.050* | |
H4W | 0.543 (8) | 1.161 (8) | 0.174 (3) | 0.050* | |
O3 | 0.1544 (5) | −0.1814 (5) | 0.19710 (16) | 0.0298 (11) | |
H5W | 0.136 (8) | −0.139 (8) | 0.2215 (19) | 0.036* | |
H6W | 0.176 (8) | −0.108 (7) | 0.181 (3) | 0.036* | |
O4 | 0.1829 (6) | 1.1261 (6) | −0.20431 (19) | 0.0400 (13) | |
H7W | 0.177 (9) | 1.080 (10) | −0.1778 (18) | 0.048* | |
H8W | 0.229 (6) | 1.200 (7) | −0.199 (3) | 0.048* | |
Br1 | −0.05312 (4) | 0.64638 (7) | 0.04411 (2) | 0.02344 (15) | |
Br2 | −0.16760 (5) | −0.12171 (7) | −0.13330 (2) | 0.03047 (17) | |
Cu | 0.16163 (6) | 0.52924 (8) | 0.01225 (3) | 0.01672 (15) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1A | 0.019 (3) | 0.016 (3) | 0.016 (2) | 0.003 (2) | −0.001 (2) | 0.001 (2) |
C2A | 0.020 (3) | 0.016 (3) | 0.025 (3) | 0.001 (2) | 0.000 (2) | −0.001 (2) |
C3A | 0.027 (3) | 0.018 (3) | 0.026 (3) | −0.003 (2) | 0.004 (2) | −0.001 (2) |
C4A | 0.023 (3) | 0.023 (3) | 0.019 (3) | 0.001 (2) | 0.001 (2) | 0.005 (2) |
C5A | 0.016 (3) | 0.018 (3) | 0.014 (2) | 0.001 (2) | −0.004 (2) | 0.001 (2) |
C6A | 0.017 (3) | 0.015 (3) | 0.021 (3) | −0.001 (2) | 0.001 (2) | 0.000 (2) |
C7A | 0.022 (3) | 0.028 (3) | 0.018 (2) | 0.003 (3) | −0.001 (2) | −0.001 (2) |
C8A | 0.039 (4) | 0.034 (4) | 0.022 (3) | −0.002 (3) | −0.011 (3) | −0.005 (3) |
N1A | 0.020 (3) | 0.015 (2) | 0.020 (2) | −0.0028 (19) | −0.001 (2) | −0.0004 (18) |
N2A | 0.023 (3) | 0.014 (2) | 0.021 (2) | −0.007 (2) | −0.005 (2) | −0.0019 (19) |
N3A | 0.021 (3) | 0.019 (3) | 0.018 (2) | 0.000 (2) | −0.005 (2) | 0.0017 (19) |
N4A | 0.026 (3) | 0.024 (3) | 0.015 (2) | 0.001 (2) | −0.004 (2) | 0.0015 (19) |
N5A | 0.018 (2) | 0.013 (2) | 0.016 (2) | −0.0007 (18) | −0.0020 (19) | 0.0007 (17) |
N6A | 0.019 (2) | 0.015 (2) | 0.021 (2) | 0.0009 (19) | 0.0037 (19) | 0.0017 (18) |
N7A | 0.028 (3) | 0.015 (2) | 0.025 (2) | 0.001 (2) | 0.001 (2) | 0.0028 (19) |
C1B | 0.016 (3) | 0.018 (3) | 0.021 (2) | 0.004 (2) | 0.003 (2) | 0.002 (2) |
C2B | 0.026 (3) | 0.019 (3) | 0.018 (3) | −0.002 (2) | −0.004 (2) | 0.002 (2) |
C3B | 0.023 (3) | 0.023 (3) | 0.029 (3) | 0.001 (2) | −0.004 (3) | 0.002 (3) |
C4B | 0.021 (3) | 0.023 (3) | 0.020 (3) | 0.001 (2) | −0.003 (2) | 0.000 (2) |
C5B | 0.023 (3) | 0.017 (3) | 0.017 (2) | −0.001 (2) | 0.003 (2) | 0.003 (2) |
C6B | 0.020 (3) | 0.016 (3) | 0.022 (3) | −0.001 (2) | 0.002 (2) | 0.001 (2) |
C7B | 0.025 (3) | 0.025 (3) | 0.020 (3) | 0.003 (3) | −0.002 (2) | −0.001 (2) |
C8B | 0.043 (4) | 0.033 (4) | 0.024 (3) | −0.004 (3) | −0.005 (3) | −0.007 (3) |
N1B | 0.021 (3) | 0.018 (2) | 0.018 (2) | −0.0035 (19) | −0.0010 (19) | 0.0033 (19) |
N2B | 0.025 (3) | 0.017 (2) | 0.020 (2) | −0.005 (2) | −0.005 (2) | −0.0017 (19) |
N3B | 0.024 (3) | 0.018 (3) | 0.022 (2) | −0.003 (2) | −0.007 (2) | −0.0026 (19) |
N4B | 0.026 (3) | 0.022 (3) | 0.014 (2) | 0.000 (2) | −0.004 (2) | −0.0011 (19) |
N5B | 0.019 (2) | 0.019 (3) | 0.016 (2) | −0.0033 (19) | −0.0054 (19) | 0.0015 (18) |
N6B | 0.016 (2) | 0.015 (2) | 0.017 (2) | 0.0018 (18) | −0.0029 (19) | 0.0031 (17) |
N7B | 0.028 (3) | 0.022 (3) | 0.030 (3) | 0.000 (2) | −0.001 (2) | 0.006 (2) |
O1 | 0.038 (3) | 0.024 (2) | 0.031 (2) | 0.008 (2) | 0.003 (2) | 0.0046 (19) |
O2 | 0.068 (4) | 0.032 (3) | 0.026 (2) | −0.023 (3) | −0.006 (3) | 0.002 (2) |
O3 | 0.041 (3) | 0.022 (2) | 0.027 (3) | −0.006 (2) | 0.002 (2) | 0.0006 (18) |
O4 | 0.057 (4) | 0.035 (3) | 0.026 (2) | −0.013 (3) | −0.009 (3) | 0.005 (2) |
Br1 | 0.0212 (3) | 0.0251 (3) | 0.0239 (3) | 0.0039 (2) | 0.0000 (2) | 0.0014 (2) |
Br2 | 0.0303 (4) | 0.0254 (3) | 0.0363 (3) | −0.0067 (3) | 0.0068 (3) | −0.0072 (3) |
Cu | 0.0210 (3) | 0.0142 (3) | 0.0144 (3) | −0.0030 (3) | −0.0043 (2) | 0.0018 (3) |
C1A—N6A | 1.346 (8) | C3B—N7B | 1.329 (9) |
C1A—C4A | 1.391 (8) | C3B—C4B | 1.403 (9) |
C1A—C5A | 1.438 (8) | C3B—H3B | 0.9500 |
C2A—N6A | 1.336 (7) | C4B—N6B | 1.320 (8) |
C2A—C3A | 1.404 (9) | C4B—H4B | 0.9500 |
C2A—H2A | 0.9500 | C5B—N1B | 1.320 (7) |
C3A—N7A | 1.328 (8) | C5B—N5B | 1.350 (8) |
C3A—H3A | 0.9500 | C6B—N2B | 1.311 (8) |
C4A—N7A | 1.338 (8) | C6B—N5B | 1.349 (7) |
C4A—H4A | 0.9500 | C6B—N3B | 1.352 (8) |
C5A—N1A | 1.317 (7) | C7B—N4B | 1.313 (8) |
C5A—N5A | 1.353 (7) | C7B—N3B | 1.376 (8) |
C6A—N2A | 1.317 (8) | C7B—C8B | 1.480 (9) |
C6A—N5A | 1.349 (7) | C8B—H8D | 0.9800 |
C6A—N3A | 1.368 (8) | C8B—H8E | 0.9800 |
C7A—N4A | 1.310 (8) | C8B—H8F | 0.9800 |
C7A—N3A | 1.378 (8) | N1B—N2B | 1.385 (7) |
C7A—C8A | 1.489 (8) | N1B—Cu | 1.951 (5) |
C8A—H8A | 0.9800 | N3B—H3NB | 0.85 (3) |
C8A—H8B | 0.9800 | N4B—N5B | 1.391 (6) |
C8A—H8C | 0.9800 | N6B—Cu | 2.125 (5) |
N1A—N2A | 1.382 (7) | O1—Cu | 2.410 (5) |
N1A—Cu | 1.953 (5) | O1—H1W | 0.83 (3) |
N3A—H3NA | 0.86 (3) | O1—H2W | 0.83 (3) |
N4A—N5A | 1.380 (7) | O2—H3W | 0.82 (3) |
N6A—Cu | 2.117 (5) | O2—H4W | 0.81 (3) |
C1B—N6B | 1.343 (7) | O3—H5W | 0.79 (3) |
C1B—C2B | 1.374 (8) | O3—H6W | 0.80 (3) |
C1B—C5B | 1.444 (8) | O4—H7W | 0.83 (3) |
C2B—N7B | 1.331 (8) | O4—H8W | 0.81 (3) |
C2B—H2B | 0.9500 | Br1—Cu | 2.7466 (12) |
N6A—C1A—C4A | 121.1 (5) | C3B—C4B—H4B | 119.9 |
N6A—C1A—C5A | 113.4 (5) | N1B—C5B—N5B | 106.8 (5) |
C4A—C1A—C5A | 125.5 (5) | N1B—C5B—C1B | 120.5 (6) |
N6A—C2A—C3A | 120.0 (6) | N5B—C5B—C1B | 132.6 (5) |
N6A—C2A—H2A | 120.0 | N2B—C6B—N5B | 113.1 (5) |
C3A—C2A—H2A | 120.0 | N2B—C6B—N3B | 141.3 (5) |
N7A—C3A—C2A | 122.6 (6) | N5B—C6B—N3B | 105.6 (5) |
N7A—C3A—H3A | 118.7 | N4B—C7B—N3B | 113.6 (5) |
C2A—C3A—H3A | 118.7 | N4B—C7B—C8B | 124.2 (6) |
N7A—C4A—C1A | 121.6 (6) | N3B—C7B—C8B | 122.1 (6) |
N7A—C4A—H4A | 119.2 | C7B—C8B—H8D | 109.5 |
C1A—C4A—H4A | 119.2 | C7B—C8B—H8E | 109.5 |
N1A—C5A—N5A | 107.3 (5) | H8D—C8B—H8E | 109.5 |
N1A—C5A—C1A | 120.2 (5) | C7B—C8B—H8F | 109.5 |
N5A—C5A—C1A | 132.5 (5) | H8D—C8B—H8F | 109.5 |
N2A—C6A—N5A | 113.6 (5) | H8E—C8B—H8F | 109.5 |
N2A—C6A—N3A | 141.3 (5) | C5B—N1B—N2B | 111.6 (5) |
N5A—C6A—N3A | 105.0 (5) | C5B—N1B—Cu | 114.2 (4) |
N4A—C7A—N3A | 114.4 (5) | N2B—N1B—Cu | 134.2 (4) |
N4A—C7A—C8A | 123.9 (6) | C6B—N2B—N1B | 102.5 (5) |
N3A—C7A—C8A | 121.8 (6) | C6B—N3B—C7B | 106.2 (5) |
C7A—C8A—H8A | 109.5 | C6B—N3B—H3NB | 119 (5) |
C7A—C8A—H8B | 109.5 | C7B—N3B—H3NB | 134 (5) |
H8A—C8A—H8B | 109.5 | C7B—N4B—N5B | 101.8 (5) |
C7A—C8A—H8C | 109.5 | C6B—N5B—C5B | 106.0 (5) |
H8A—C8A—H8C | 109.5 | C6B—N5B—N4B | 112.7 (5) |
H8B—C8A—H8C | 109.5 | C5B—N5B—N4B | 141.2 (5) |
C5A—N1A—N2A | 111.8 (5) | C4B—N6B—C1B | 117.2 (5) |
C5A—N1A—Cu | 114.2 (4) | C4B—N6B—Cu | 131.1 (4) |
N2A—N1A—Cu | 133.9 (4) | C1B—N6B—Cu | 111.7 (4) |
C6A—N2A—N1A | 102.1 (5) | C3B—N7B—C2B | 116.5 (5) |
C6A—N3A—C7A | 105.4 (5) | Cu—O1—H1W | 111 (6) |
C6A—N3A—H3NA | 128 (5) | Cu—O1—H2W | 115 (6) |
C7A—N3A—H3NA | 126 (5) | H1W—O1—H2W | 101 (4) |
C7A—N4A—N5A | 101.5 (5) | H3W—O2—H4W | 112 (9) |
C6A—N5A—C5A | 105.2 (5) | H5W—O3—H6W | 103 (8) |
C6A—N5A—N4A | 113.7 (5) | H7W—O4—H8W | 105 (9) |
C5A—N5A—N4A | 141.1 (5) | N1B—Cu—N1A | 175.5 (2) |
C2A—N6A—C1A | 117.8 (5) | N1B—Cu—N6A | 97.78 (19) |
C2A—N6A—Cu | 130.8 (4) | N1A—Cu—N6A | 80.67 (19) |
C1A—N6A—Cu | 111.4 (4) | N1B—Cu—N6B | 80.60 (19) |
C3A—N7A—C4A | 116.8 (5) | N1A—Cu—N6B | 100.64 (19) |
N6B—C1B—C2B | 122.2 (5) | N6A—Cu—N6B | 175.62 (18) |
N6B—C1B—C5B | 113.0 (5) | N1B—Cu—O1 | 91.16 (19) |
C2B—C1B—C5B | 124.8 (5) | N1A—Cu—O1 | 84.78 (19) |
N7B—C2B—C1B | 121.4 (6) | N6A—Cu—O1 | 93.64 (17) |
N7B—C2B—H2B | 119.3 | N6B—Cu—O1 | 82.35 (17) |
C1B—C2B—H2B | 119.3 | N1B—Cu—Br1 | 92.56 (15) |
N7B—C3B—C4B | 122.5 (6) | N1A—Cu—Br1 | 91.68 (15) |
N7B—C3B—H3B | 118.7 | N6A—Cu—Br1 | 92.06 (13) |
C4B—C3B—H3B | 118.7 | N6B—Cu—Br1 | 92.08 (13) |
N6B—C4B—C3B | 120.2 (6) | O1—Cu—Br1 | 172.72 (11) |
N6B—C4B—H4B | 119.9 | ||
N6A—C2A—C3A—N7A | 1.2 (9) | N6B—C1B—C2B—N7B | −1.4 (9) |
N6A—C1A—C4A—N7A | −1.6 (9) | C5B—C1B—C2B—N7B | −178.9 (5) |
C5A—C1A—C4A—N7A | 179.5 (5) | N7B—C3B—C4B—N6B | −1.9 (10) |
N6A—C1A—C5A—N1A | 2.0 (8) | N6B—C1B—C5B—N1B | −1.3 (8) |
C4A—C1A—C5A—N1A | −179.0 (6) | C2B—C1B—C5B—N1B | 176.3 (6) |
N6A—C1A—C5A—N5A | −179.4 (6) | N6B—C1B—C5B—N5B | −178.6 (6) |
C4A—C1A—C5A—N5A | −0.5 (10) | C2B—C1B—C5B—N5B | −1.0 (10) |
N5A—C5A—N1A—N2A | 0.1 (6) | N5B—C5B—N1B—N2B | 0.3 (6) |
C1A—C5A—N1A—N2A | 179.0 (5) | C1B—C5B—N1B—N2B | −177.6 (5) |
N5A—C5A—N1A—Cu | 177.7 (3) | N5B—C5B—N1B—Cu | −179.9 (4) |
C1A—C5A—N1A—Cu | −3.4 (7) | C1B—C5B—N1B—Cu | 2.2 (7) |
N5A—C6A—N2A—N1A | 0.8 (6) | N5B—C6B—N2B—N1B | −0.8 (6) |
N3A—C6A—N2A—N1A | 178.5 (7) | N3B—C6B—N2B—N1B | −179.3 (8) |
C5A—N1A—N2A—C6A | −0.5 (6) | C5B—N1B—N2B—C6B | 0.3 (6) |
Cu—N1A—N2A—C6A | −177.5 (4) | Cu—N1B—N2B—C6B | −179.4 (4) |
N2A—C6A—N3A—C7A | −179.3 (8) | N2B—C6B—N3B—C7B | 179.2 (8) |
N5A—C6A—N3A—C7A | −1.4 (6) | N5B—C6B—N3B—C7B | 0.6 (6) |
N4A—C7A—N3A—C6A | 0.7 (7) | N4B—C7B—N3B—C6B | 0.3 (7) |
C8A—C7A—N3A—C6A | −179.9 (6) | C8B—C7B—N3B—C6B | 179.9 (6) |
N3A—C7A—N4A—N5A | 0.3 (7) | N3B—C7B—N4B—N5B | −1.0 (6) |
C8A—C7A—N4A—N5A | −179.1 (6) | C8B—C7B—N4B—N5B | 179.4 (6) |
N2A—C6A—N5A—C5A | −0.7 (7) | N2B—C6B—N5B—C5B | 1.0 (7) |
N3A—C6A—N5A—C5A | −179.3 (4) | N3B—C6B—N5B—C5B | −179.9 (5) |
N2A—C6A—N5A—N4A | −179.6 (5) | N2B—C6B—N5B—N4B | 179.6 (5) |
N3A—C6A—N5A—N4A | 1.8 (6) | N3B—C6B—N5B—N4B | −1.3 (6) |
N1A—C5A—N5A—C6A | 0.3 (6) | N1B—C5B—N5B—C6B | −0.8 (6) |
C1A—C5A—N5A—C6A | −178.4 (6) | C1B—C5B—N5B—C6B | 176.8 (6) |
N1A—C5A—N5A—N4A | 178.8 (6) | N1B—C5B—N5B—N4B | −178.7 (6) |
C1A—C5A—N5A—N4A | 0.1 (12) | C1B—C5B—N5B—N4B | −1.2 (12) |
C7A—N4A—N5A—C6A | −1.3 (6) | C7B—N4B—N5B—C6B | 1.4 (6) |
C7A—N4A—N5A—C5A | −179.7 (7) | C7B—N4B—N5B—C5B | 179.3 (7) |
C3A—C2A—N6A—C1A | −0.8 (8) | C3B—C4B—N6B—C1B | 0.6 (8) |
C3A—C2A—N6A—Cu | 178.8 (4) | C3B—C4B—N6B—Cu | 179.2 (4) |
C4A—C1A—N6A—C2A | 1.0 (8) | C2B—C1B—N6B—C4B | 1.0 (8) |
C5A—C1A—N6A—C2A | −180.0 (5) | C5B—C1B—N6B—C4B | 178.7 (5) |
C4A—C1A—N6A—Cu | −178.7 (4) | C2B—C1B—N6B—Cu | −177.8 (5) |
C5A—C1A—N6A—Cu | 0.3 (6) | C5B—C1B—N6B—Cu | −0.1 (6) |
C2A—C3A—N7A—C4A | −1.7 (8) | C4B—C3B—N7B—C2B | 1.5 (9) |
C1A—C4A—N7A—C3A | 1.9 (8) | C1B—C2B—N7B—C3B | 0.2 (9) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2A—H2A···N2B | 0.95 | 2.38 | 3.137 (8) | 137 |
C3A—H3A···Br1i | 0.95 | 3.11 | 4.058 (6) | 173 |
N3A—H3NA···O2 | 0.86 (3) | 1.82 (3) | 2.657 (7) | 165 (7) |
C4B—H4B···N2A | 0.95 | 2.52 | 3.276 (8) | 136 |
C4B—H4B···Br1ii | 0.95 | 3.09 | 3.848 (6) | 138 |
N3B—H3NB···Br2 | 0.85 (3) | 2.34 (3) | 3.190 (5) | 173 (7) |
O1—H1W···Br1iii | 0.83 (3) | 2.42 (3) | 3.229 (5) | 166 (6) |
O1—H2W···Br2ii | 0.83 (3) | 2.49 (3) | 3.301 (5) | 168 (8) |
O2—H3W···Br1ii | 0.82 (3) | 2.43 (3) | 3.237 (5) | 173 (9) |
O2—H4W···O3iv | 0.81 (3) | 1.89 (4) | 2.691 (7) | 167 (10) |
O3—H5W···O4v | 0.79 (3) | 2.08 (6) | 2.746 (7) | 141 (8) |
O3—H6W···N7A | 0.80 (3) | 2.17 (4) | 2.931 (7) | 159 (9) |
O4—H7W···N7B | 0.83 (3) | 2.12 (3) | 2.939 (7) | 171 (9) |
O4—H8W···Br2iv | 0.81 (3) | 2.56 (6) | 3.272 (6) | 147 (8) |
Symmetry codes: (i) x, y−1, z; (ii) x+1/2, y+1/2, z; (iii) x+1/2, y−1/2, z; (iv) x+1/2, y+3/2, z; (v) x, −y+1, z+1/2. |
[ZnBr2(C8H7N7)2]·H2O | Z = 2 |
Mr = 645.62 | F(000) = 636 |
Triclinic, P1 | Dx = 1.884 Mg m−3 |
a = 8.396 (2) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 12.305 (3) Å | Cell parameters from 467 reflections |
c = 12.724 (3) Å | θ = 2.5–29.4° |
α = 112.53 (2)° | µ = 4.63 mm−1 |
β = 107.78 (3)° | T = 293 K |
γ = 92.16 (2)° | Prismatic, brown |
V = 1138.1 (5) Å3 | 0.40 × 0.30 × 0.20 mm |
Bruker–Nonius KappaCCD diffractometer | 5090 independent reflections |
Radiation source: normal-focus sealed tube | 3636 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
Detector resolution: 9 pixels mm-1 | θmax = 27.5°, θmin = 3.0° |
CCD rotation images, thick slices scans | h = −10→9 |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | k = −15→15 |
Tmin = 0.270, Tmax = 0.433 | l = −16→16 |
12306 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)] = 0.047 | Hydrogen site location: mixed |
wR(F2) = 0.136 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0621P)2 + 1.6216P] where P = (Fo2 + 2Fc2)/3 |
5090 reflections | (Δ/σ)max < 0.001 |
315 parameters | Δρmax = 0.70 e Å−3 |
2 restraints | Δρmin = −0.74 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Data were collected on a Bruker-Nonius KappaCCD diffractometer equipped with Oxford Cryostream 700 apparatus. The structures were solved by direct methods and refined by the full matrix least squares method with anisotropic displacement parameters for non-H atoms. |
x | y | z | Uiso*/Ueq | ||
C1A | 0.7622 (6) | −0.1592 (4) | 0.2765 (5) | 0.0327 (10) | |
C2A | 0.8753 (7) | −0.1982 (5) | 0.3538 (5) | 0.0419 (12) | |
H2A | 0.910796 | −0.152912 | 0.437155 | 0.050* | |
C3A | 0.8825 (7) | −0.3578 (5) | 0.1909 (6) | 0.0473 (13) | |
H3A | 0.919272 | −0.429248 | 0.157203 | 0.057* | |
C4A | 0.7757 (8) | −0.3151 (5) | 0.1150 (6) | 0.0499 (14) | |
H4A | 0.747553 | −0.357230 | 0.031646 | 0.060* | |
C5A | 0.6867 (6) | −0.0542 (4) | 0.3258 (5) | 0.0328 (10) | |
C6A | 0.5263 (6) | 0.0829 (4) | 0.3413 (4) | 0.0323 (10) | |
C7A | 0.3906 (6) | 0.0624 (5) | 0.1628 (5) | 0.0394 (11) | |
C8A | 0.2693 (8) | 0.0807 (7) | 0.0606 (5) | 0.0581 (17) | |
H8A | 0.273891 | 0.023930 | −0.014849 | 0.087* | |
H8B | 0.299509 | 0.160286 | 0.068690 | 0.087* | |
H8C | 0.156311 | 0.069745 | 0.061995 | 0.087* | |
N1A | 0.7145 (5) | 0.0033 (4) | 0.4421 (4) | 0.0394 (10) | |
N2A | 0.6147 (6) | 0.0897 (4) | 0.4513 (4) | 0.0391 (10) | |
H2NA | 0.607 (7) | 0.138 (4) | 0.517 (3) | 0.047* | |
N3A | 0.4115 (5) | 0.1312 (4) | 0.2834 (4) | 0.0352 (9) | |
N4A | 0.4836 (5) | −0.0220 (4) | 0.1438 (4) | 0.0394 (10) | |
N5A | 0.5711 (5) | −0.0065 (4) | 0.2614 (4) | 0.0334 (9) | |
N6A | 0.7115 (6) | −0.2166 (4) | 0.1556 (4) | 0.0445 (11) | |
N7A | 0.9342 (6) | −0.2990 (4) | 0.3114 (5) | 0.0472 (11) | |
C1B | 0.6464 (6) | 0.3015 (4) | 0.7817 (4) | 0.0335 (10) | |
C2B | 0.7013 (8) | 0.3681 (5) | 0.9056 (5) | 0.0525 (15) | |
H2B | 0.653069 | 0.434809 | 0.935948 | 0.063* | |
C3B | 0.8740 (8) | 0.2402 (6) | 0.9334 (6) | 0.0560 (16) | |
H3B | 0.954592 | 0.215786 | 0.984276 | 0.067* | |
C4B | 0.8170 (7) | 0.1699 (5) | 0.8100 (6) | 0.0476 (14) | |
H4B | 0.860005 | 0.100278 | 0.780550 | 0.057* | |
C5B | 0.5245 (6) | 0.3357 (4) | 0.6953 (4) | 0.0333 (10) | |
C6B | 0.3573 (6) | 0.4326 (4) | 0.6126 (5) | 0.0364 (11) | |
C7B | 0.3548 (6) | 0.5944 (4) | 0.7617 (5) | 0.0352 (10) | |
C8B | 0.3150 (7) | 0.7132 (5) | 0.8251 (6) | 0.0474 (13) | |
H8D | 0.201770 | 0.703714 | 0.826530 | 0.071* | |
H8E | 0.323254 | 0.762347 | 0.783202 | 0.071* | |
H8F | 0.394277 | 0.750544 | 0.906771 | 0.071* | |
N1B | 0.4712 (6) | 0.2739 (4) | 0.5773 (4) | 0.0408 (10) | |
N2B | 0.3645 (5) | 0.3337 (4) | 0.5216 (4) | 0.0412 (10) | |
N3B | 0.2928 (5) | 0.5339 (4) | 0.6371 (4) | 0.0376 (10) | |
H3NB | 0.245 (6) | 0.563 (5) | 0.588 (4) | 0.045* | |
N4B | 0.4512 (5) | 0.5378 (4) | 0.8169 (4) | 0.0351 (9) | |
N5B | 0.4513 (5) | 0.4356 (3) | 0.7202 (3) | 0.0310 (8) | |
N6B | 0.7007 (5) | 0.2004 (4) | 0.7322 (4) | 0.0388 (10) | |
N7B | 0.8197 (7) | 0.3407 (5) | 0.9827 (5) | 0.0585 (14) | |
Zn | 0.25393 (7) | 0.24715 (5) | 0.33982 (5) | 0.03379 (16) | |
Br1 | 0.00038 (7) | 0.11388 (5) | 0.29176 (6) | 0.04583 (17) | |
Br2 | 0.20342 (8) | 0.39584 (6) | 0.26552 (7) | 0.0577 (2) | |
O1W | 0.1184 (9) | 0.6539 (6) | 0.5184 (5) | 0.103 (2) | |
H1W | 0.061280 | 0.710175 | 0.572921 | 0.124* | |
H2W | 0.050768 | 0.636549 | 0.434186 | 0.124* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1A | 0.034 (2) | 0.031 (2) | 0.036 (3) | 0.0062 (18) | 0.013 (2) | 0.015 (2) |
C2A | 0.044 (3) | 0.046 (3) | 0.038 (3) | 0.013 (2) | 0.015 (2) | 0.019 (3) |
C3A | 0.052 (3) | 0.036 (3) | 0.053 (4) | 0.015 (2) | 0.022 (3) | 0.014 (3) |
C4A | 0.058 (3) | 0.042 (3) | 0.040 (3) | 0.009 (3) | 0.014 (3) | 0.009 (3) |
C5A | 0.033 (2) | 0.033 (2) | 0.034 (3) | 0.0084 (19) | 0.012 (2) | 0.016 (2) |
C6A | 0.030 (2) | 0.035 (2) | 0.029 (3) | 0.0062 (18) | 0.0089 (19) | 0.010 (2) |
C7A | 0.034 (2) | 0.051 (3) | 0.033 (3) | 0.010 (2) | 0.011 (2) | 0.018 (2) |
C8A | 0.056 (4) | 0.081 (5) | 0.034 (3) | 0.032 (3) | 0.012 (3) | 0.022 (3) |
N1A | 0.046 (2) | 0.039 (2) | 0.037 (2) | 0.0150 (18) | 0.0148 (19) | 0.018 (2) |
N2A | 0.046 (2) | 0.041 (2) | 0.028 (2) | 0.0166 (19) | 0.0121 (19) | 0.0122 (19) |
N3A | 0.033 (2) | 0.044 (2) | 0.030 (2) | 0.0121 (17) | 0.0098 (17) | 0.0169 (19) |
N4A | 0.041 (2) | 0.046 (2) | 0.030 (2) | 0.0111 (18) | 0.0093 (18) | 0.015 (2) |
N5A | 0.033 (2) | 0.035 (2) | 0.031 (2) | 0.0075 (16) | 0.0090 (17) | 0.0143 (18) |
N6A | 0.050 (3) | 0.040 (2) | 0.038 (3) | 0.009 (2) | 0.010 (2) | 0.015 (2) |
N7A | 0.054 (3) | 0.044 (3) | 0.049 (3) | 0.018 (2) | 0.019 (2) | 0.022 (2) |
C1B | 0.037 (2) | 0.031 (2) | 0.031 (3) | 0.0064 (19) | 0.007 (2) | 0.013 (2) |
C2B | 0.064 (4) | 0.045 (3) | 0.034 (3) | 0.020 (3) | 0.001 (3) | 0.013 (3) |
C3B | 0.057 (4) | 0.064 (4) | 0.053 (4) | 0.018 (3) | 0.008 (3) | 0.038 (3) |
C4B | 0.046 (3) | 0.041 (3) | 0.060 (4) | 0.017 (2) | 0.016 (3) | 0.027 (3) |
C5B | 0.036 (2) | 0.029 (2) | 0.030 (3) | 0.0048 (18) | 0.009 (2) | 0.009 (2) |
C6B | 0.036 (2) | 0.036 (3) | 0.033 (3) | 0.0078 (19) | 0.006 (2) | 0.014 (2) |
C7B | 0.032 (2) | 0.038 (3) | 0.038 (3) | 0.0065 (19) | 0.015 (2) | 0.016 (2) |
C8B | 0.055 (3) | 0.039 (3) | 0.052 (4) | 0.022 (2) | 0.024 (3) | 0.018 (3) |
N1B | 0.047 (2) | 0.037 (2) | 0.032 (2) | 0.0122 (18) | 0.0070 (19) | 0.0116 (19) |
N2B | 0.043 (2) | 0.039 (2) | 0.034 (2) | 0.0134 (18) | 0.0041 (19) | 0.013 (2) |
N3B | 0.037 (2) | 0.040 (2) | 0.036 (2) | 0.0131 (18) | 0.0079 (18) | 0.019 (2) |
N4B | 0.040 (2) | 0.032 (2) | 0.029 (2) | 0.0082 (17) | 0.0104 (17) | 0.0097 (18) |
N5B | 0.036 (2) | 0.0290 (19) | 0.023 (2) | 0.0067 (16) | 0.0060 (16) | 0.0093 (16) |
N6B | 0.038 (2) | 0.034 (2) | 0.042 (3) | 0.0103 (17) | 0.0131 (19) | 0.013 (2) |
N7B | 0.062 (3) | 0.068 (3) | 0.040 (3) | 0.025 (3) | 0.006 (2) | 0.023 (3) |
Zn | 0.0331 (3) | 0.0369 (3) | 0.0277 (3) | 0.0079 (2) | 0.0052 (2) | 0.0137 (2) |
Br1 | 0.0391 (3) | 0.0392 (3) | 0.0574 (4) | 0.0062 (2) | 0.0161 (2) | 0.0187 (3) |
Br2 | 0.0535 (4) | 0.0593 (4) | 0.0712 (5) | 0.0088 (3) | 0.0129 (3) | 0.0451 (4) |
O1W | 0.152 (6) | 0.104 (5) | 0.063 (4) | 0.078 (4) | 0.028 (4) | 0.046 (3) |
C1A—N6A | 1.338 (7) | C1B—C5B | 1.460 (7) |
C1A—C2A | 1.388 (7) | C2B—N7B | 1.322 (7) |
C1A—C5A | 1.466 (7) | C2B—H2B | 0.9300 |
C2A—N7A | 1.330 (7) | C3B—N7B | 1.324 (8) |
C2A—H2A | 0.9300 | C3B—C4B | 1.382 (9) |
C3A—N7A | 1.335 (8) | C3B—H3B | 0.9300 |
C3A—C4A | 1.381 (8) | C4B—N6B | 1.340 (7) |
C3A—H3A | 0.9300 | C4B—H4B | 0.9300 |
C4A—N6A | 1.329 (7) | C5B—N1B | 1.313 (7) |
C4A—H4A | 0.9300 | C5B—N5B | 1.366 (6) |
C5A—N1A | 1.310 (7) | C6B—N2B | 1.339 (7) |
C5A—N5A | 1.372 (6) | C6B—N5B | 1.341 (6) |
C6A—N3A | 1.330 (6) | C6B—N3B | 1.342 (6) |
C6A—N2A | 1.337 (6) | C7B—N4B | 1.305 (6) |
C6A—N5A | 1.339 (6) | C7B—N3B | 1.379 (7) |
C7A—N4A | 1.315 (7) | C7B—C8B | 1.482 (7) |
C7A—N3A | 1.390 (7) | C8B—H8D | 0.9600 |
C7A—C8A | 1.487 (7) | C8B—H8E | 0.9600 |
C8A—H8A | 0.9600 | C8B—H8F | 0.9600 |
C8A—H8B | 0.9600 | N1B—N2B | 1.381 (6) |
C8A—H8C | 0.9600 | N2B—Zn | 2.018 (4) |
N1A—N2A | 1.371 (6) | N3B—H3NB | 0.85 (2) |
N2A—H2NA | 0.84 (2) | N4B—N5B | 1.382 (6) |
N3A—Zn | 2.059 (4) | Zn—Br2 | 2.3581 (9) |
N4A—N5A | 1.384 (6) | Zn—Br1 | 2.4017 (11) |
C1B—N6B | 1.330 (6) | O1W—H1W | 1.0251 |
C1B—C2B | 1.381 (8) | O1W—H2W | 0.9795 |
N6A—C1A—C2A | 122.7 (5) | N7B—C2B—H2B | 118.7 |
N6A—C1A—C5A | 117.0 (4) | C1B—C2B—H2B | 118.7 |
C2A—C1A—C5A | 120.3 (5) | N7B—C3B—C4B | 123.3 (5) |
N7A—C2A—C1A | 121.4 (5) | N7B—C3B—H3B | 118.4 |
N7A—C2A—H2A | 119.3 | C4B—C3B—H3B | 118.4 |
C1A—C2A—H2A | 119.3 | N6B—C4B—C3B | 121.1 (5) |
N7A—C3A—C4A | 121.7 (5) | N6B—C4B—H4B | 119.5 |
N7A—C3A—H3A | 119.2 | C3B—C4B—H4B | 119.5 |
C4A—C3A—H3A | 119.2 | N1B—C5B—N5B | 108.6 (4) |
N6A—C4A—C3A | 123.0 (6) | N1B—C5B—C1B | 123.8 (5) |
N6A—C4A—H4A | 118.5 | N5B—C5B—C1B | 127.5 (4) |
C3A—C4A—H4A | 118.5 | N2B—C6B—N5B | 110.8 (4) |
N1A—C5A—N5A | 110.0 (4) | N2B—C6B—N3B | 143.1 (5) |
N1A—C5A—C1A | 122.7 (4) | N5B—C6B—N3B | 106.1 (4) |
N5A—C5A—C1A | 127.1 (5) | N4B—C7B—N3B | 113.8 (4) |
N3A—C6A—N2A | 143.3 (5) | N4B—C7B—C8B | 124.0 (5) |
N3A—C6A—N5A | 110.0 (4) | N3B—C7B—C8B | 122.2 (5) |
N2A—C6A—N5A | 106.7 (4) | C7B—C8B—H8D | 109.5 |
N4A—C7A—N3A | 115.8 (4) | C7B—C8B—H8E | 109.5 |
N4A—C7A—C8A | 121.6 (5) | H8D—C8B—H8E | 109.5 |
N3A—C7A—C8A | 122.7 (5) | C7B—C8B—H8F | 109.5 |
C7A—C8A—H8A | 109.5 | H8D—C8B—H8F | 109.5 |
C7A—C8A—H8B | 109.5 | H8E—C8B—H8F | 109.5 |
H8A—C8A—H8B | 109.5 | C5B—N1B—N2B | 109.4 (4) |
C7A—C8A—H8C | 109.5 | C6B—N2B—N1B | 105.0 (4) |
H8A—C8A—H8C | 109.5 | C6B—N2B—Zn | 139.0 (3) |
H8B—C8A—H8C | 109.5 | N1B—N2B—Zn | 115.6 (3) |
C5A—N1A—N2A | 105.5 (4) | C6B—N3B—C7B | 105.6 (4) |
C6A—N2A—N1A | 110.4 (4) | C6B—N3B—H3NB | 128 (4) |
C6A—N2A—H2NA | 125 (4) | C7B—N3B—H3NB | 125 (4) |
N1A—N2A—H2NA | 124 (4) | C7B—N4B—N5B | 101.7 (4) |
C6A—N3A—C7A | 102.1 (4) | C6B—N5B—C5B | 106.2 (4) |
C6A—N3A—Zn | 131.9 (4) | C6B—N5B—N4B | 112.9 (4) |
C7A—N3A—Zn | 124.5 (3) | C5B—N5B—N4B | 140.8 (4) |
C7A—N4A—N5A | 101.0 (4) | C1B—N6B—C4B | 115.7 (5) |
C6A—N5A—C5A | 107.4 (4) | C2B—N7B—C3B | 115.2 (6) |
C6A—N5A—N4A | 111.0 (4) | N2B—Zn—N3A | 105.76 (17) |
C5A—N5A—N4A | 141.5 (4) | N2B—Zn—Br2 | 106.45 (13) |
C4A—N6A—C1A | 114.9 (5) | N3A—Zn—Br2 | 118.70 (12) |
C2A—N7A—C3A | 116.3 (5) | N2B—Zn—Br1 | 109.44 (14) |
N6B—C1B—C2B | 122.1 (5) | N3A—Zn—Br1 | 102.56 (12) |
N6B—C1B—C5B | 115.0 (5) | Br2—Zn—Br1 | 113.50 (4) |
C2B—C1B—C5B | 122.9 (5) | H1W—O1W—H2W | 107.6 |
N7B—C2B—C1B | 122.6 (6) | ||
N6A—C1A—C2A—N7A | −3.1 (8) | N6B—C1B—C2B—N7B | 4.8 (10) |
C5A—C1A—C2A—N7A | 174.1 (5) | C5B—C1B—C2B—N7B | −175.6 (6) |
N7A—C3A—C4A—N6A | −3.0 (9) | N7B—C3B—C4B—N6B | −0.2 (10) |
N6A—C1A—C5A—N1A | 173.9 (5) | N6B—C1B—C5B—N1B | −0.6 (7) |
C2A—C1A—C5A—N1A | −3.5 (7) | C2B—C1B—C5B—N1B | 179.8 (5) |
N6A—C1A—C5A—N5A | −1.2 (7) | N6B—C1B—C5B—N5B | −178.4 (5) |
C2A—C1A—C5A—N5A | −178.6 (5) | C2B—C1B—C5B—N5B | 2.0 (8) |
N5A—C5A—N1A—N2A | −0.3 (5) | N5B—C5B—N1B—N2B | 1.5 (6) |
C1A—C5A—N1A—N2A | −176.1 (4) | C1B—C5B—N1B—N2B | −176.7 (4) |
N3A—C6A—N2A—N1A | 178.4 (6) | N5B—C6B—N2B—N1B | −0.9 (6) |
N5A—C6A—N2A—N1A | −0.9 (6) | N3B—C6B—N2B—N1B | 176.8 (7) |
C5A—N1A—N2A—C6A | 0.7 (6) | N5B—C6B—N2B—Zn | 172.4 (4) |
N2A—C6A—N3A—C7A | −178.7 (7) | N3B—C6B—N2B—Zn | −9.9 (12) |
N5A—C6A—N3A—C7A | 0.6 (5) | C5B—N1B—N2B—C6B | −0.4 (6) |
N2A—C6A—N3A—Zn | −12.6 (10) | C5B—N1B—N2B—Zn | −175.5 (3) |
N5A—C6A—N3A—Zn | 166.7 (3) | N2B—C6B—N3B—C7B | −177.2 (7) |
N4A—C7A—N3A—C6A | −0.4 (6) | N5B—C6B—N3B—C7B | 0.5 (5) |
C8A—C7A—N3A—C6A | 178.6 (5) | N4B—C7B—N3B—C6B | −0.9 (6) |
N4A—C7A—N3A—Zn | −168.0 (4) | C8B—C7B—N3B—C6B | 178.7 (5) |
C8A—C7A—N3A—Zn | 11.1 (7) | N3B—C7B—N4B—N5B | 0.8 (5) |
N3A—C7A—N4A—N5A | 0.1 (6) | C8B—C7B—N4B—N5B | −178.7 (5) |
C8A—C7A—N4A—N5A | −178.9 (5) | N2B—C6B—N5B—C5B | 1.8 (6) |
N3A—C6A—N5A—C5A | −178.9 (4) | N3B—C6B—N5B—C5B | −176.8 (4) |
N2A—C6A—N5A—C5A | 0.7 (5) | N2B—C6B—N5B—N4B | 178.5 (4) |
N3A—C6A—N5A—N4A | −0.6 (5) | N3B—C6B—N5B—N4B | −0.1 (6) |
N2A—C6A—N5A—N4A | 179.0 (4) | N1B—C5B—N5B—C6B | −2.0 (5) |
N1A—C5A—N5A—C6A | −0.3 (5) | C1B—C5B—N5B—C6B | 176.1 (5) |
C1A—C5A—N5A—C6A | 175.3 (5) | N1B—C5B—N5B—N4B | −177.2 (5) |
N1A—C5A—N5A—N4A | −177.7 (5) | C1B—C5B—N5B—N4B | 0.9 (10) |
C1A—C5A—N5A—N4A | −2.1 (9) | C7B—N4B—N5B—C6B | −0.4 (5) |
C7A—N4A—N5A—C6A | 0.3 (5) | C7B—N4B—N5B—C5B | 174.6 (6) |
C7A—N4A—N5A—C5A | 177.6 (6) | C2B—C1B—N6B—C4B | −2.5 (8) |
C3A—C4A—N6A—C1A | 2.0 (8) | C5B—C1B—N6B—C4B | 177.8 (5) |
C2A—C1A—N6A—C4A | 1.0 (7) | C3B—C4B—N6B—C1B | 0.3 (8) |
C5A—C1A—N6A—C4A | −176.3 (5) | C1B—C2B—N7B—C3B | −4.3 (10) |
C1A—C2A—N7A—C3A | 2.1 (8) | C4B—C3B—N7B—C2B | 2.1 (10) |
C4A—C3A—N7A—C2A | 0.8 (8) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2A—H2A···Br1i | 0.93 | 3.13 | 3.995 (6) | 155 |
N2A—H2NA···N1B | 0.84 (2) | 2.09 (4) | 2.786 (6) | 139 (5) |
N2A—H2NA···N6B | 0.84 (2) | 2.39 (4) | 3.126 (6) | 145 (5) |
C2B—H2B···N4B | 0.93 | 2.62 | 3.276 (7) | 129 |
C4B—H4B···Br1i | 0.93 | 2.86 | 3.791 (6) | 176 |
N3B—H3NB···O1W | 0.85 (2) | 1.85 (3) | 2.669 (6) | 163 (6) |
O1W—H1W···Br1ii | 1.03 | 2.39 | 3.375 (6) | 162 |
O1W—H2W···N7Aiii | 0.98 | 2.03 | 2.901 (7) | 148 |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x, −y+1, −z+1; (iii) x−1, y+1, z. |
Acknowledgements
The authors would like to acknowledge the contribution of the COST Action CA17120-Chemobrionics. Thanks are also due to the Centro Regionale di Competenza NTAP of Regione Campania (Italy) for the X-ray facility.
References
Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119. Web of Science CrossRef CAS IUCr Journals Google Scholar
Ambrosanio, P., Centore, R., Concilio, S., Panunzi, B., Sirigu, A. & Tirelli, N. (1999). Polymer, 40, 4923–4928. CrossRef CAS Google Scholar
Borbone, F., Caruso, U., Centore, R., DeMaria, A., Fort, A., Fusco, M., Panunzi, B., Roviello, A. & Tuzi, A. (2004). Eur. J. Inorg. Chem. 2004, 2467–2476. CSD CrossRef Google Scholar
Bruker (2001). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bussetti, G., Campione, M., Riva, M., Picone, A., Raimondo, L., Ferraro, L., Hogan, C., Palummo, M., Brambilla, A., Finazzi, M., Duò, L., Sassella, A. & Ciccacci, F. (2014). Adv. Funct. Mater. 24, 958–963. CrossRef CAS Google Scholar
Centore, R., Concilio, S., Panunzi, B., Sirigu, A. & Tirelli, N. (1999). J. Polym. Sci. A Polym. Chem. 37, 603–608. CrossRef CAS Google Scholar
Centore, R., Fusco, S., Capobianco, A., Piccialli, V., Zaccaria, S. & Peluso, A. (2013). Eur. J. Org. Chem. 2013, 3721–3728. CSD CrossRef CAS Google Scholar
Centore, R., Manfredi, C., Capobianco, A., Volino, S., Ferrara, M. V., Carella, A., Fusco, S. & Peluso, A. (2017). J. Org. Chem. 82, 5155–5161. CSD CrossRef CAS PubMed Google Scholar
Centore, R., Manfredi, C., Fusco, S., Maglione, C., Carella, A., Capobianco, A., Peluso, A., Colonna, D. & Di Carlo, A. (2015). J. Mol. Struct. 1093, 119–124. CSD CrossRef CAS Google Scholar
Centore, R., Panunzi, B., Roviello, A., Sirigu, A. & Villano, P. (1996). J. Polym. Sci. A Polym. Chem. 34, 3203–3211. CrossRef CAS Google Scholar
Cotton, F. A., Wilkinson, G., Murillo, C. A. & Bochmann, M. (1999). In Advanced Inorganic Chemistry, 6th ed. New York: John Wiley & Sons Inc. Google Scholar
Deneva, V., Dobrikov, G., Crochet, A., Nedeltcheva, D., Fromm, K. M. & Antonov, L. (2019). J. Org. Chem. 15, 1898–1906. CAS Google Scholar
Duisenberg, A. J. M., Hooft, R. W. W., Schreurs, A. M. M. & Kroon, J. (2000). J. Appl. Cryst. 33, 893–898. Web of Science CrossRef CAS IUCr Journals Google Scholar
Duisenberg, A. J. M., Kroon-Batenburg, L. M. J. & Schreurs, A. M. M. (2003). J. Appl. Cryst. 36, 220–229. Web of Science CrossRef CAS IUCr Journals Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Fusco, S., Parisi, E., Carella, A., Capobianco, A., Peluso, A., Manfredi, C., Borbone, F. & Centore, R. (2018). Cryst. Growth Des. 18, 6293–6301. CSD CrossRef CAS Google Scholar
Goodman, M. (1995). Nature, 378, 237–238. CrossRef CAS PubMed Google Scholar
Horiuchi, S., Kobayashi, K., Kumai, R. & Ishibashi, S. (2017). Nat. Commun. 8, 14426. CSD CrossRef PubMed Google Scholar
Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226–235. Web of Science CrossRef CAS IUCr Journals Google Scholar
Martin, C. Y. (2009). J. Comput. Aided Mol. Des. 23, 693–704. CrossRef PubMed CAS Google Scholar
McNaught, A. D. & Wilkinson, A. (1997). In IUPAC Compendium of Chemical Terminology, 2nd ed. Oxford: Blackwell Science. Google Scholar
Nonius (1999). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Parisi, E., Capasso, D., Capobianco, A., Peluso, A., Di Gaetano, S., Fusco, S., Manfredi, C., Mozzillo, R., Pinto, G. & Centore, R. (2020). Dalton Trans. 49, 14452–14462. CSD CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sutradhar, M., Alegria, E. C. B. A., Mahmudov, T., Guedes da Silva, F. C. & Pombeiro, A. J. L. (2016). RSC Adv., 6, 8079–8088. CSD CrossRef CAS Google Scholar
Takjoo, R. & Centore, R. (2013). J. Mol. Struct. 1031, 180–185. Web of Science CSD CrossRef CAS Google Scholar
Taylor, P. J., Van der Zwan, G. & Antonov, L. (2014). In Tautomerism: Methods and Theories. Weinheim: Wiley-VCH Verlag GmbH & Co. Google Scholar
Todorov, A. R., Nieger, M. & Helaja, J. (2012). Chem. Eur. J. 18, 7269–7277. CSD CrossRef CAS PubMed Google Scholar
Wang, W., Hellinga, W. & Beese, L. S. (2011). Proc. Natl Acad. Sci. USA, 108, 17644–17648. CrossRef CAS PubMed Google Scholar
Watson, J. D. & Crick, F. H. (1953a). Nature, 171, 737–738. CrossRef PubMed CAS Google Scholar
Watson, J. D. & Crick, F. H. (1953b). Nature, 171, 964–967. CrossRef PubMed CAS Google Scholar
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