Shet M Prakash1, S Naveen2, N K Lokanath3, P A Suchetan1, Ismail Warad4. 1. Dept. of Chemistry, University College of Science, Tumkur University, Tumkur, 572103, India. 2. Department of Basic Sciences, School of Engineering and Technology, Jain, University, Bangalore 562 112, India. 3. Department of Studies in Physics, University of Mysore, Manasagangotri, Mysuru 570 006, India. 4. Department of Chemistry, Science College, An-Najah National University, PO Box 7, Nablus, Palestinian Territories.
Abstract
2-Amino-pyridine and citric acid mixed in 1:1 and 3:1 ratios in ethanol yielded crystals of two 2-amino-pyridinium citrate salts, viz. C5H7N2+·C6H7O7- (I) (systematic name: 2-amino-pyridin-1-ium 3-carb-oxy-2-carb-oxy-methyl-2-hy-droxy-propano-ate), and 3C5H7N2+·C6H5O73- (II) [systematic name: tris-(2-amino-pyridin-1-ium) 2-hy-droxy-propane-1,2,3-tri-carboxyl-ate]. The supra-molecular synthons present are analysed and their effect upon the crystal packing is presented in the context of crystal engineering. Salt I is formed by the protonation of the pyridine N atom and deprotonation of the central carb-oxy-lic group of citric acid, while in II all three carb-oxy-lic groups of the acid are deprotonated and the charges are compensated for by three 2-amino-pyridinium cations. In both structures, a complex supra-molecular three-dimensional architecture is formed. In I, the supra-molecular aggregation results from Namino-H⋯Oacid, Oacid⋯H-Oacid, Oalcohol-H⋯Oacid, Namino-H⋯Oalcohol, Npy-H⋯Oalcohol and Car-H⋯Oacid inter-actions. The mol-ecular conformation of the citrate ion (CA3-) in II is stabilized by an intra-molecular Oalcohol-H⋯Oacid hydrogen bond that encloses an S(6) ring motif. The complex three-dimensional structure of II features Namino-H⋯Oacid, Npy-H⋯Oacid and several Car-H⋯Oacid hydrogen bonds. In the crystal of I, the common charge-assisted 2-amino-pyridinium-carboxyl-ate heterosynthon exhibited in many 2-amino-pyridinium carboxyl-ates is not observed, instead chains of N-H⋯O hydrogen bonds and hetero O-H⋯O dimers are formed. In the crystal of II, the 2-amino-pyridinium-carboxyl-ate heterosynthon is sustained, while hetero O-H⋯O dimers are not observed. The crystal structures of both salts display a variety of hydrogen bonds as almost all of the hydrogen-bond donors and acceptors present are involved in hydrogen bonding.
2-Amino-pyridine and citric acid mixed in 1:1 and 3:1 ratios in ethanol yielded crystals of two 2-amino-pyridinium citrate salts, viz. C5H7N2+·C6H7O7- (I) (systematic name: 2-amino-pyridin-1-ium 3-carb-oxy-2-carb-oxy-methyl-2-hy-droxy-propano-ate), and 3C5H7N2+·C6H5O73- (II) [systematic name: tris-(2-amino-pyridin-1-ium) 2-hy-droxy-propane-1,2,3-tri-carboxyl-ate]. The supra-molecular synthons present are analysed and their effect upon the crystal packing is presented in the context of crystal engineering. Salt I is formed by the protonation of the pyridine N atom and deprotonation of the central carb-oxy-lic group of citric acid, while in II all three carb-oxy-lic groups of the acid are deprotonated and the charges are compensated for by three 2-amino-pyridiniumcations. In both structures, a complex supra-molecular three-dimensional architecture is formed. In I, the supra-molecular aggregation results from Namino-H⋯Oacid, Oacid⋯H-Oacid, Oalcohol-H⋯Oacid, Namino-H⋯Oalcohol, Npy-H⋯Oalcohol and Car-H⋯Oacid inter-actions. The mol-ecular conformation of the citrate ion (CA3-) in II is stabilized by an intra-molecular Oalcohol-H⋯Oacidhydrogen bond that encloses an S(6) ring motif. The complex three-dimensional structure of II features Namino-H⋯Oacid, Npy-H⋯Oacid and several Car-H⋯Oacidhydrogen bonds. In the crystal of I, the common charge-assisted 2-amino-pyridinium-carboxyl-ate heterosynthon exhibited in many 2-amino-pyridinium carboxyl-ates is not observed, instead chains of N-H⋯O hydrogen bonds and hetero O-H⋯O dimers are formed. In the crystal of II, the 2-amino-pyridinium-carboxyl-ate heterosynthon is sustained, while hetero O-H⋯O dimers are not observed. The crystal structures of both salts display a variety of hydrogen bonds as almost all of the hydrogen-bond donors and acceptors present are involved in hydrogen bonding.
Systematic structural and statistical analysis focusing on the identification of robust supramolecular synthons or patterns are essential for crystal engineering and the design of new solid-state structures with desired properties. Organiccrystals, especially salts, are now considered as potential materials for optical applications because of their flexibility in molecular design (Jayanalina et al., 2015a
▸), thermal stability and delocalized clouds of π electrons (Jayanalina et al., 2015b
▸). An analysis of the Cambridge Structural Database (Groom et al., 2016 ▸) by Bis & Zaworotko (2005 ▸) revealed that 77% of compounds that contain both the 2-aminopyridine and carboxylic acid moieties generate 2-aminopyridine–carboxylic acid supramolecular heterosynthons rather than carboxylic acid or 2-aminopyridine supramolecular homosynthons. In the absence of other competing functionalities, the occurrence of heterosynthons increased to 97%. Several salts and co-crystals containing 2-aminopyridine or 2-acetaminopyridine and a carboxylic acid moiety have been reported (Jayanalina et al., 2015a
▸,b
▸; Bis & Zaworotko, 2005 ▸; Aakeröy et al., 2006 ▸; Jasmine et al., 2015 ▸; Jin et al., 2001 ▸). In all of these reported structures, the charge-assisted 2-aminopyridinium-carboxylate or neutral 2-acetaminopyridine–carboxylic heterosynthon is observed, as suggested by statistical analysis. Keeping this in mind, the crystal structure analyses of two 2-aminopyridinium citratesalts, C5H7N2
+·C6H7O7
− (I) and 3C5H7N2
+·C6H5O7
3− (II), were undertaken in order to study the packing patterns and identify the supramolecular synthons present in each salt.
Structural commentary
The carboxylic groups in citric acid have pKa values of 3.128 (central –COOH group), 4.762 and 6.396 (terminal –COOH groups). Thus, an equimolar mixing of citric acid and 2-aminopyridine resulted in the formation of salt I (2-AMP+·CA−), whose structure is illustrated in Fig. 1 ▸. Here, the pyridine N atom is protonated and the central carboxylic group of the acid is deprotonated. The two C—O bond lengths of the central carboxylic group have values of 1.235 (3) Å for C6—O7 and 1.264 (3) Å for C6—O6, indicating partial double-bond character for both bonds. However, the two C—O bonds in each of the terminal carboxylic groups have different bond lengths [1.207 (3) Å for C3=O2 and 1.327 (3) Å for C3—O3, and 1.209 (3) Å for C5=O5 and 1.319 (3) Å for C5—O4], indicating double-bond character for one C—O bond and single-bond character for the other. These observations clearly confirm the deprotonation of the central carboxylic group (C6/O6/O7). The two terminal carboxylic groups in I have different conformations. In one of them (C5/O4/O5) the O—H and C=O bonds are in a syn conformation while in the other (C3/O2/O3), they have an anti conformation (Fig. 1 ▸). In the asymmetric unit of I, the 2-aminopyridinium cation, 2-AMP+, and the citrate anion, CA-, are linked via Namino—H⋯Oacid(t1) hydrogen bonds [acid(t1) = C3/O2/O3], viz. N2—H2D⋯O2 (Table 1 ▸ and Fig. 1 ▸).
Figure 1
A view of the molecular structure of salt I, with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines [Table 1 ▸; acid(t1) = C3/O2/O3; acid(t2) = C5/O4/O5; acid(c) = C6/O6/O7].
Table 1
Hydrogen-bond geometry (Å, °) for I
D—H⋯A
D—H
H⋯A
D⋯A
D—H⋯A
O1—H1⋯O6i
0.82
1.86
2.681 (4)
177
N1—H1A⋯O1ii
0.86
2.09
2.895 (4)
156
N2—H2C⋯O1ii
0.86
2.34
3.076 (5)
144
N2—H2D⋯O2
0.86
2.09
2.935 (5)
168
O3—H3⋯O7i
0.82
1.75
2.547 (4)
164
O4—H4⋯O6iii
0.82
1.82
2.601 (4)
158
C9—H9⋯O3iv
0.93
2.57
3.351 (5)
142
Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .
The asymmetric unit of salt II, illustrated in Fig. 2 ▸, consists of one citrate trianion, CA3− [(C5H5O7)3−], and three 2-AMP+cations (2-AMP1, 2-AMP2 and 2-AMP3), wherein the pyridine N atom of each 2-AMP unit is protonated and all three carboxylic groups of the acid are deprotonated. This is supported by the observation that the C—O bonds of all the three carboxylic groups have similar bond lengths, in the range 1.231 (2)–1.266 (2) Å, which is an indication of the partial double-bond character of all of the C—O bonds resulting from deprotonation. The molecular conformation of the CA3− anion is stabilized by an intramolecular Oalcohol—H⋯Oacid(t1) hydrogen bond, namely O1—H1O⋯O3, that closes an S(6) ring motif (Table 2 ▸, Fig. 2 ▸).
Figure 2
A view of the molecular structure of salt II, with the atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Intramolecular and some intermolecular interactions are shown as dashed lines [Table 2 ▸; acid(t1) = C3/O2/O3; acid (t2) = C5/O4/O5; acid(c) = C6/O6/O7; symmetry code: (i) −x + , y − , −z + ]. For clarity, C-bound H atoms have been omitted.
Table 2
Hydrogen-bond geometry (Å, °) for II
D—H⋯A
D—H
H⋯A
D⋯A
D—H⋯A
O1—H1O⋯O3
0.91 (3)
1.84 (3)
2.681 (2)
152 (3)
N3—H3A⋯O3
0.86
2.07
2.905 (3)
164
N4—H4⋯O2
0.86
1.81
2.666 (2)
175
N1—H1B⋯O6
0.86
2.07
2.893 (2)
161
N6—H6B⋯O7
0.86
2.09
2.928 (2)
164
N1—H1A⋯O7i
0.86
2.12
2.948 (2)
162
N2—H2⋯O1i
0.86
2.00
2.760 (2)
144
N2—H2⋯O7i
0.86
2.55
3.304 (2)
144
C9—H9⋯O6ii
0.93
2.60
3.372 (3)
141
C10—H10⋯O2ii
0.93
2.51
3.419 (3)
167
C11—H11⋯O2iii
0.93
2.41
3.294 (3)
160
N3—H3B⋯O4iv
0.86
2.09
2.851 (2)
146
C13—H13⋯O6iv
0.93
2.40
3.301 (3)
163
N5—H5⋯O4i
0.86
1.77
2.591 (2)
160
N6—H6A⋯O5i
0.86
2.07
2.916 (3)
169
C20—H20⋯O7v
0.93
2.60
3.463 (3)
155
C21—H21⋯O3v
0.93
2.43
3.334 (3)
164
Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) .
In the asymmetric unit of salt II, the three 2-AMP+cations are in different environments and interact with the CA3− anion in different ways [Fig. 2 ▸ and Table 2 ▸; acid(t1) = C3/O2/O3; acid(t2) = C5/O4/O5; acid(c) = C6/O6/O7]. The first cation, 2-AMP1, interacts with the anion via a discrete Namino—H⋯Oacid(c) hydrogen bond, namely N1—H1B⋯O6. The second cation, 2-AMP2, interacts with the CA3− anion via a charge-assisted 2-aminopyridinium-carboxylate (8) heterosynthon consisting of Namino—H⋯Oacid(t1) (N3—H3A⋯O3) and Npy—H⋯Oacid(t1) (N4—H4⋯O2) hydrogen bonds. The third cation, 2-AMP3, interacts with the anion via a discrete Namino—H⋯Oacid(c) hydrogen bond, namely N6—H6B⋯O7.
Supramolecular features
Full details of the hydrogen-bonding interactions in the crystal of salt I are given in Table 1 ▸, and illustrated in Figs. 3 ▸ and 4 ▸. In the crystal of I, the cations and anions of adjacent units are interconnected by a Car—H⋯Oacid(t1) interactions, viz. C9—H9⋯O3, while adjacent anions related by b-glide symmetry form chains running along the b-axis direction, consisting of an (8) heterosynthon of Oacid(c)⋯H—Oacid(t1) and Oalcohol—H⋯Oacid(c) hydrogen bonds, namely O3—H3⋯O7i and O1—H1⋯O6i; see Fig. 3 ▸ and Table 1 ▸. The 2-AMP+ and CA− ions further aggregate to form sheets parallel to the ac plane (Fig. 4 ▸). The sheets consist of chains of Oacid(t2)—H⋯Oacid(c) hydrogen bonds, namely O4—H4⋯O6iii, running along the a-axis direction and linking the twofold-symmetry-related CA− anions (Table 1 ▸, Fig. 4 ▸). Adjacent chains are connected by 2-AMP+ ions via Namino—H⋯Oacid(t1)=Chydrogen bonds, namely N2—H2D⋯O2, and an (6) heterosynthon of Namino—H⋯Oalcohol and Npy—H⋯Oalcoholhydrogen bonds, N2—H2C⋯O1ii and N1—H1A⋯O1ii, respectively, is formed (Table 1 ▸, Fig. 4 ▸). Overall, a three-dimensional supramolecular architecture is observed. All of the strong hydrogen-bond acceptors and hydrogen-bond donors in I are involved in hydrogen bonding. However, the most reproducible charge-assisted 2-aminopyridinium–carboxylate heterosynthon, found in the crystal structures of many 2-aminopyridinium carboxylates (Bis & Zaworotko, 2005 ▸), is not present; instead chains of N—H⋯O hydrogen bonds and hetero O—H⋯O dimers are observed.
Figure 3
A partial view along the a axis of the crystal packing of salt I, showing the chains of CA− anions running along the b-axis direction. Attached to the chains and bridging two anions are the 2-AMP+ cations. The various intermolecular interactions are shown as dashed lines (Table 1 ▸).
Figure 4
A partial view along the b axis of the crystal packing of salt I, illustrating the layer-like structure. Red and blue dashed lines denote the various intermolecular interactions (Table 1 ▸).
In the crystal of II, all of the strong hydrogen-bond donors and acceptors are utilized in a supramolecular association. Full details of the hydrogen-bonding interactions are given in Table 2 ▸, and illustrated in Figs. 2 ▸, 5 ▸ and 6 ▸. A number of the Car—H groups are also involved in C—H⋯O hydrogen bonds (Table 2 ▸). However, in contrast to I, the alcoholic OH group is not involved in intermolecular hydrogen bonding as it is locked into an intramolecular O1—H1O⋯O3acid(t1) hydrogen bond. The CA3− anion and the first 2-AMP+cation (2-AMP1) form sheets lying parallel to the (101) plane (Fig. 5 ▸
a and 5b). The sheet consists of alternating CA3− and 2-AMP+ ions, forming chains via C11—H11⋯O2iii interactions, with adjacent anti-parallel chains linked by C10—H10⋯O2ii, N1—H1A⋯O7i, N1—H1B⋯O6, N2—H2⋯O7i and N2—H2⋯O1i hydrogen bonds (Table 2 ▸, Fig. 5 ▸). On the other hand, the citrate and the second 2-AMP+ ions (2-AMP2) propagate alternately along the a-axis direction to form ribbons (Fig. 6 ▸
a) consisting of alternating (8) heterosynthons of N3—H3A⋯O3 and N4—H4⋯O2 hydrogen bonds (Table 2 ▸) and (11) heterosynthons of N3—H3B⋯O4 and C13—H13⋯O6 hydrogen bonds (Table 2 ▸). Finally, the third 2-AMP+ ions (2-AMP3) are interlinked to the adjacent citrate ions, forming ribbons of alternating (8) heterosynthons, of N5—H5⋯O4i and N6—H6A⋯O5i hydrogen bonds (Table 2 ▸), and (10) heterosynthons of C21—H21⋯O3vi and C20—H20⋯O7vi interactions (Table 2 ▸) along the a-axis direction (Fig. 6 ▸
b). Adjacent ribbons are further interconnected by N6—H6B⋯O7 hydrogen bonds to form corrugated sheets parallel to the ab plane (Table 2 ▸, Fig. 6 ▸
b). Overall a complex supramolecular three-dimensional structure is formed.
Figure 5
(a) Partial crystal packing of salt II, involving citrate (green) and 2-AMP1 (red) ions, showing the layer-like structure lying in plane (202). (b) An alternative view, along the b axis, of the layer-like structure. The hydrogen bonds and other intermolecular interactions are shown as dashed lines (Table 2 ▸).
Figure 6
(a) Partial crystal packing of salt II, involving citrate (green) and 2-AMP2 (blue) ions. Red dashed lines denote various intermolecular interactions and solid blue lines denote intramolecular hydrogen bonds (Table 2 ▸). (b) Partial crystal packing of salt II, involving citrate (green) and 2-AMP3 (yellow) ions. Dashed lines denote various intermolecular interactions (Table 2 ▸).
Database survey
A survey of the Cambridge Structural Database (CSD, Version 5.39, last update May 2018; Groom et al., 2016 ▸) revealed 80 organic structures involving a citric acid moiety in the form of solvates/hydrates, salts/salt hydrates and co-crystals. 25 structures among these are salts/salt hydrates of citric acid (deprotonated to different extents) with various organiccations. It is observed that most of the organiccitrates appear as their hydrates, with the exception of a few (including I and II). The most common hydrogen bonds observed in these hydrated salts are Namine—H⋯Ocitric, Namine—H⋯Owater and Owater—H⋯Ocitric, forming different supramolecular architectures. In the absence of a water molecule, the most common hydrogen bonds are Namine—H⋯Ocitric and Ocitric—H⋯Ocitric. However, the nature of these supramolecular synthons varies from one structure to another, depending on the nature of the organiccations.Similarly, the crystal structures of several salts with 2-AMP+ as the cation are reported. Single-crystal structures of ten salts that contain both a 2-aminopyridine and a carboxylic acid moiety have been reported (Bis & Zaworotko, 2005 ▸). They include: 2-aminopyridinium 4-aminobenzoate, 2-aminopyridinium isophthalate, bis(2-aminopyridinium) terephthalate, 2-amino-5-methylpyridinium benzoate, bis(2-amino-5-methylpyridinium) 5-tertbutylisophthalate, 2-amino-5-methylpyridinium terephthalate, bis(2-amino-5-methylpyridinium) 2,6-naphthalenedicarboxylate, bis(2-amino 5-methylpyridinium) adipate adipic acid, bis(2-amino-5-methylpyridinium) 2,5-thiophenedicarboxylate 2,5-thiophenedicarboxylic acid, and indomethacin 2-amino-5-methylpyridinium. In all the reported structures, the most reproducible pattern is the charge-assisted 2-aminopyridinium–carboxylate heterosynthon seen in salt II. Similarly, in the crystal structure of 2-amino-3-methylpyridinium ortho-phthalate (Jin et al., 2001 ▸), the two 2-amino-3-methylpyridinium ions are interconnected to the ortho-phthalate ion via a charge-assisted 2-aminopyridinium–carboxylate heterosynthon. This robust pattern is also observed in the crystal structures of 2-aminopyridinium 6-chloronicotinate (Jasmine et al., 2015 ▸) and 2-amino-5-chloropyridinium pyridine-2-carboxylate monohydrate (Jayanalina et al., 2015a
▸). Single-crystal structures of ten co-crystals that contain 2-acetaminopyridine and a carboxylic acid moiety: 2-acetaminopyridine/fumaric acid have been reported by Aakeröy et al. (2006 ▸). They include: 2-acetaminopyridine/succinic acid, 2-acetaminopyridine/glutaric acid, 2-acetaminopyridine /adipic acid, 2-acetaminopyridine/pimelic acid, 2-acetaminopyridine/suberic acid, 2-acetamino-pyridine/azelaic acid, 2-acetaminopyridine/sebacic acid, 2-acetaminopyridine/3,5-dimethylbenzoic acid, and 2-acetaminopyridine/5-nitroisophthalic acid. Although these are neutral compounds wherein there is no transfer of proton from carboxylic acid to the 2-acetaminopyridine moiety, the most repetitive pattern observed in these structures is the neutral 2-acetaminopyridine–carboxylic acid (8) heterosynthon. This is very similar to the charge-assisted 2-aminopyridinium–carboxylate heterosynthon except for the positioning of the hydrogen atom, on either the O or N atom.The crystal structure of 2-amino 5-chloropyridinium-l-tartarate (Jayanalina et al., 2015b
▸) shows that despite of the presence of other competing functionalities on the carboxylic acid (two alcoholic OH groups in tartaric acid), the most frequent 2-aminopyridinium–carboxylate heterosynthon is still observed. However, the presence of the alcoholic OH group in citric acid has resulted in a deviation from the regular trend as the charge-assisted 2-aminopyridinium–carboxylate heterosynthon is not observed in I; instead chains of N—H⋯O hydrogen bonds and hetero O—H⋯O dimers are observed. The 2-aminopyridinium–carboxylate heterosynthon is sustained in the crystal structure of II because of the non-availability of the alcoholic OH group for intermolecular hydrogen bonding.Hence, the study of the crystal structure of 2-aminopyridinium citrate, mixed in a 2:1 ratio, would be highly significant in understanding the packing-pattern trends observed in this family of salts. Unfortunately, despite a number of attempts, we have not been able to obtain good-quality single crystals of this salt.
Synthesis and crystallization
A solution of citric acid (3 mmol, 0.576 g) in ethanol (15 ml) was added to an ethanolic solution (15 ml) of 2-aminopyridine (3 mmol, 0.282 g). The resulting solution was heated and the hot solution was filtered. Slow evaporation of the solution resulted in the formation of colourless prismaticcrystals of salt I (m.p. 493 K). Single crystals of salt II were obtained from a similar procedure; an ethanolic solution (15 ml) of citric acid (3 mmol, 0.576 g) was mixed with an ethanolic solution (15 ml) of 2-aminopyridine (9 mmol, 0.846 g).
Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. In salt I, the OH H atom (H1) was positioned geometrically and refined as riding: O—H = 0.82 Å with U
iso(H) = 1.5U
eq(O). In salt II, the OH H atom (H1O) was located in a difference-Fourier map and freely refined. In both salts, the other H atoms were positioned geometrically and refined as riding: N—H = 0.86 Å, C—H = 0.93–0.97 Å with U
iso(H) = 1.2U
eq(N, C).
Table 3
Experimental details
I
II
Crystal data
Chemical formula
C5H7N2+·C6H7O7−
3C5H7N2+·C6H5O73−
Mr
286.24
474.48
Crystal system, space group
Orthorhombic, Pbca
Monoclinic, P21/n
Temperature (K)
296
296
a, b, c (Å)
9.000 (11), 10.721 (13), 27.21 (3)
10.0297 (17), 10.6564 (14), 21.986 (4)
α, β, γ (°)
90, 90, 90
90, 101.426 (9), 90
V (Å3)
2625 (5)
2303.3 (7)
Z
8
4
Radiation type
Mo Kα
Mo Kα
μ (mm−1)
0.12
0.11
Crystal size (mm)
0.27 × 0.22 × 0.19
0.22 × 0.19 × 0.17
Data collection
Diffractometer
Bruker APEXII
Bruker APEXII
Absorption correction
Multi-scan (SADABS; Bruker, 2009 ▸)
Multi-scan (SADABS; Bruker, 2009 ▸)
Tmin, Tmax
0.968, 0.977
0.977, 0.982
No. of measured, independent and observed [I > 2σ(I)] reflections
8086, 2977, 2143
13120, 5242, 3779
Rint
0.099
0.056
(sin θ/λ)max (Å−1)
0.649
0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S
0.066, 0.195, 1.06
0.052, 0.149, 1.05
No. of reflections
2977
5242
No. of parameters
184
311
H-atom treatment
H-atom parameters constrained
H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)
0.29, −0.30
0.27, −0.21
Computer programs: APEX2, SAINT-Plus and XPREP (Bruker, 2009 ▸), SHELXT2016 (Sheldrick, 2015a
▸), SHELXL2016 (Sheldrick, 2015b
▸) and Mercury (Macrae et al., 2008 ▸).
Crystal structure: contains datablock(s) I, II, Global. DOI: 10.1107/S2056989018009787/su5449sup1.cifStructure factors: contains datablock(s) I. DOI: 10.1107/S2056989018009787/su5449Isup2.hklStructure factors: contains datablock(s) II. DOI: 10.1107/S2056989018009787/su5449IIsup3.hklClick here for additional data file.Supporting information file. DOI: 10.1107/S2056989018009787/su5449Isup4.cmlClick here for additional data file.Supporting information file. DOI: 10.1107/S2056989018009787/su5449IIsup5.cmlCCDC references: 1854628, 1854627Additional supporting information: crystallographic information; 3D view; checkCIF report
Primary atom site location: structure-invariant direct methods
Least-squares matrix: full
Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.066
Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.195
H-atom parameters constrained
S = 1.06
w = 1/[σ2(Fo2) + (0.1065P)2] where P = (Fo2 + 2Fc2)/3
2977 reflections
(Δ/σ)max < 0.001
184 parameters
Δρmax = 0.29 e Å−3
0 restraints
Δρmin = −0.30 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.
Primary atom site location: structure-invariant direct methods
Least-squares matrix: full
Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052
Hydrogen site location: mixed
wR(F2) = 0.149
H atoms treated by a mixture of independent and constrained refinement
S = 1.05
w = 1/[σ2(Fo2) + (0.0673P)2 + 0.409P] where P = (Fo2 + 2Fc2)/3
5242 reflections
(Δ/σ)max < 0.001
311 parameters
Δρmax = 0.27 e Å−3
0 restraints
Δρmin = −0.21 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.