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Structures of disodium hydrogen citrate mono­hydrate, Na2HC6H5O7(H2O), and di­ammonium sodium citrate, (NH4)2NaC6H5O7, from powder diffraction data

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aIllinois Mathematics and Science Academy, 1500 Sullivan Road, Aurora, IL 60506 , USA, and bDepartment of Chemistry, North Central College, 131 S. Loomis, St., Naperville IL, 60540 , USA
*Correspondence e-mail: kaduk@polycrystallography.com

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 2 April 2020; accepted 28 August 2020; online 4 September 2020)

The crystal structures of disodium hydrogen citrate monohydrate, Na2HC6H5O7(H2O), and di­ammonium sodium citrate, (NH4)2NaC6H5O7, have been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. In NaHC6H5O7(H2O), the NaO6 coordination polyhedra share edges, forming zigzag layers lying parallel to the bc plane. The hydro­phobic methyl­ene groups occupy the inter­layer spaces. The carb­oxy­lic acid group makes a strong charge-assisted hydrogen bond to the central carboxyl­ate group. The hydroxyl group makes an intra­molecular hydrogen bond to an ionized terminal carboxyl­ate oxygen atom. Each hydrogen atom of the water mol­ecule acts as a donor, to a terminal carboxyl­ate and the hydroxyl group. Both the Na substructure and the hydrogen bonding differ from those of the known phase Na2HC6H5O7(H2O)1.5. In (NH4)2NaC6H5O7, the NaO6 coordination octa­hedra share corners, making double zigzag chains propagating along the b-axis direction. Each hydrogen atom of the ammonium ions acts as a donor in a discrete N—H⋯O hydrogen bond. The hydroxyl group forms an intra­molecular O—H⋯O hydrogen bond to a terminal carboxyl­ate oxygen atom.

1. Chemical context

A systematic study of the crystal structures of Group 1 (alkali metal) citrate salts has been reported in Rammohan & Kaduk (2018[Rammohan, A. & Kaduk, J. A. (2018). Acta Cryst. B74, 239-252.]). The study was extended to ammonium citrates in Wheatley & Kaduk (2019[Wheatley, A. M. & Kaduk, J. A. (2019). Powder Diffr. 34, 35-43.]). Na2HC6H5O7(H2O) was an accidental product of an extension of the program to mixed ammonium–group 1 citrates, and (NH4)2NaC6H5O7 was an intended product. Another product in the series is (NH4)2KC6H5O7 (Patel et al., 2020[Patel, N. V., Golab, J. T. & Kaduk, J. A. (2020). IUCrData, 5, x200612.]). Known sodium citrates include two polymorphs of NaH2C6H5O7 (Rammohan & Kaduk, 2016b[Rammohan, A. & Kaduk, J. A. (2016b). Acta Cryst. E72, 854-857.]; Glusker et al., 1965[Glusker, J. P., Van Der Helm, D., Love, W. E., Dornberg, M., Minkin, J. A., Johnson, C. K. & Patterson, A. L. (1965). Acta Cryst. 19, 561-572.]), Na2.5H0.5C6H5O7 (Rammohan & Kaduk, 2017[Rammohan, A. & Kaduk, J. A. (2017). Acta Cryst. E73, 286-290.]), Na2HC6H5O7(H2O)1.5 (Rammohan & Kaduk, 2016c[Rammohan, A. & Kaduk, J. A. (2016c). Acta Cryst. E72, 1159-1162.]), Na3C6H5O7 (Rammohan & Kaduk, 2016a[Rammohan, A. & Kaduk, J. A. (2016a). Acta Cryst. E72, 793-796.]), Na3C6H5O7(H2O)2 (Fischer & Palladino, 2003[Fischer, A. & Palladino, G. (2003). Acta Cryst. E59, m1080-m1082.]), and Na3C6H5O7(H2O)5.5 (Viossat et al., 1986[Viossat, B., Rodier, N. & Eberle, J. (1986). Bull. Soc. Chim. Fr. 4, 522-525.]).

As part of our ongoing studies in this area, we now report the syntheses and structures of disodium hydrogen citrate monohydrate, Na2HC6H5O7(H2O), (I)[link], and di­ammonium sodium citrate, (NH4)2NaC6H5O7, (II)[link].

[Scheme 1]

2. Structural commentary

The structure of (I)[link] was solved and refined from powder X-ray data and optimized by density functional theory (DFT) calculations (see Experimental section) and is illustrated in Fig. 1[link]. The root-mean-square Cartesian displacement of the non-hydrogen citrate atoms in the Rietveld refined and DFT-optimized structures is 0.0764 Å (Fig. 2[link]). The excellent agreement between the two structures is strong evidence that the experimental structure is correct (van de Streek & Neumann, 2014[Streek, J. van de & Neumann, M. A. (2014). Acta Cryst. B70, 1020-1032.]). All of the citrate bond distances, bond angles, and torsion angles fall within the normal ranges indicated by a Mercury Mogul geometry check (Macrae et al., 2020[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.]). The citrate anion occurs in the gauche, trans-conformation (about C2—C3 and C3—C4, respectively), which is one of the two low-energy conformations of an isolated citrate ion (Rammohan & Kaduk, 2018[Rammohan, A. & Kaduk, J. A. (2018). Acta Cryst. B74, 239-252.]). The central carboxyl­ate group and the hydroxyl group exhibit a small twist (O16—C6—C3—O17 torsion angle = 10.3°) from the normal planar arrangement. The Mulliken overlap populations indicate that the Na—O bonds are ionic. Both Na cations are six-coordinate (distorted octa­hedral). The bond-valence sums for Na20 and Na21 are 1.09 and 1.04 respectively.

[Figure 1]
Figure 1
The asymmetric unit of (I)[link] with the atom numbering and 50% probability spheres.
[Figure 2]
Figure 2
Comparison of the refined and optimized structures of (I)[link]: the refined structure is in red, and the DFT-optimized structure is in blue.

The citrate anion triply chelates to Na20 through the terminal carboxyl­ate oxygen atom O14, the central carboxyl­ate oxygen atom O16, and the hydroxyl group O17. All oxygen atoms except O12 coordinate to at least one Na cation.

The Bravais–Friedel–Donnay–Harker (Bravais, 1866[Bravais, A. (1866). Études Cristallographiques. Paris: Gauthier Villars.]; Friedel, 1907[Friedel, G. (1907). Bull. Soc. Fr. Mineral. 30, 326-455.]; Donnay & Harker, 1937[Donnay, J. D. H. & Harker, D. (1937). Am. Mineral. 22, 446-467.]) method suggests that we might expect blocky morphology for disodium hydrogen citrate monohydrate. No preferred orientation model was necessary in the refinement.

The structure of (II)[link] was solved and refined from powder X-ray data and optimized by density functional theory (DFT) calculations (see Experimental section) and is illustrated in Fig. 3[link]. The root-mean-square Cartesian displacement of the non-hydrogen citrate atoms in the Rietveld refined and DFT-optimized structures is 0.067 Å (Fig. 4[link]). The r.m.s. displacement of the sodium ions is 0.037 Å and the equivalent values for the ammonium ions N20 and N21 are 0.148 and 0.147 Å, respectively. The excellent agreement between the two structures is strong evidence that the experimental structure is correct (van de Streek & Neumann, 2014[Streek, J. van de & Neumann, M. A. (2014). Acta Cryst. B70, 1020-1032.]). Almost all of the citrate bond distances, bond angles, and torsion angles fall within the normal ranges indicated by a Mercury Mogul geometry check (Macrae et al., 2020[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.]). Only the O13—C5—C4 angle of 117.3° [average = 119.4 (7)°, 6-score = 3.2] is flagged as unusual. Mogul finds a population of three similar angles and the standard uncertainty is exceptionally low at 0.7°, so the Z-score is not of concern. The citrate anion occurs in the trans, trans-conformation (about C2—C3 and C3—C4), which is one of the two low-energy conformations of an isolated citrate ion (Rammohan & Kaduk, 2018[Rammohan, A. & Kaduk, J. A. (2018). Acta Cryst. B74, 239-252.]). The central carboxyl­ate group and the hydroxyl group exhibit a very small twist [O17—C3—C6—O15 = 0.34°] from the normal planar arrangement. The Mulliken overlap populations indicate that the Na—O bonds are ionic.

[Figure 3]
Figure 3
The asymmetric unit of (II)[link] with the atom numbering and 50% probability spheres.
[Figure 4]
Figure 4
Comparison of the refined and optimized structures of (II)[link]: the refined structure is in red, and the DFT-optimized structure is in blue.

The Bravais–Friedel–Donnay–Harker method suggests that we might expect platy morphology for di­ammonium sodium citrate, with {100} as the major faces. A 2nd order spherical harmonic model was included in the refinement. The texture index was only 1.006, indicating that preferred orientation was not significant in this rotated capillary specimen.

3. Supra­molecular features

In the extended structure of (I)[link], the NaO6 coordination polyhedra share edges to form zigzag layers lying parallel to the bc plane (Fig. 5[link]). The layers are conveniently viewed along [[\overline{1}]10] (Figs. 6[link] and 7[link]). The hydro­phobic methyl­ene groups occupy the inter­layer spaces. The carb­oxy­lic acid O13—H24 group makes a strong (16.8 kcal mol−1) charge-assisted hydrogen bond to the central carboxyl­ate oxygen atom O15. The energies of the O—H⋯O hydrogen bonds were calculated using the correlation of Rammohan & Kaduk (2018[Rammohan, A. & Kaduk, J. A. (2018). Acta Cryst. B74, 239-252.]). The hydroxyl group O17—H18 makes an intra­molecular hydrogen bond to the ionized terminal carboxyl­ate oxygen atom O12. Each hydrogen atom of the water mol­ecule O19 acts as a donor, to O12 and the hydroxyl group O17 (Table 1[link]).

Table 1
Hydrogen-bond geometry (Å, °) for (I) (DFT)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
O13—H24⋯O15i 1.06 1.42 2.485 175
O17—H18⋯O12 1.00 1.62 2.578 179
O19—H23⋯O17ii 0.97 2.18 3.076 154
O19—H22⋯O12iii 1.00 1.62 2.615 172
Symmetry codes: (i) [-x+{\script{1\over 2}}, -y, z-{\script{1\over 2}}]; (ii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (iii) [-x+{\script{1\over 2}}, -y+1, z-{\script{1\over 2}}].
[Figure 5]
Figure 5
The crystal structure of (I)[link] viewed down the c axis.
[Figure 6]
Figure 6
View of the Na/O layers in (I)[link], viewed down [[\overline{1}]10].
[Figure 7]
Figure 7
View of the crystal structure of (I)[link], viewed down [[\overline{1}]10].

In the extended structure of Na2HC6H5O7(H2O)1.5 (Rammohan & Kaduk, 2016c[Rammohan, A. & Kaduk, J. A. (2016c). Acta Cryst. E72, 1159-1162.]), the carb­oxy­lic acid makes a hydrogen bond to a terminal ionized carboxyl­ate group, while in this monohydrate, the –COOH group hydrogen bonds to the central ionized carboxyl­ate. In the sesquihydrate, the hydroxyl group hydrogen bonds to a terminal carboxyl­ate, while in this monohydrate the hydroxyl group forms an intra­molecular hydrogen bond. In the sesquihydrate, all three independent water mol­ecules bridge Na cations; in this monohydrate the water mol­ecule also bridges two Na. In the sesquihydrate, there are eight-membered rings of Na cations, while in this monohydrate structure the Na coordination spheres form layers.

The triclinic unit cell of Na2HC6H5O7(H2O)1.5 corresponds roughly to a 1/2 subcell of the current Pbca cell. The transformation matrix from the current cell to the standard ortho­rhom­bic cell is [0 1 0 / 0 0 [\overline{1}] / [\overline{1}] 0 0], and the transformation matrix from the standard cell to the subcell is [[\overline{1}] 0 0 / −1/2 − 1/2 1/2 / −1/2 1/2 1/2]. Given the differences in the Na substructures and the hydrogen bonding, the similarities of the cells are a coincidence.

The CRYSTAL14 (Dovesi et al., 2014[Dovesi, R., Orlando, R., Erba, A., Zicovich-Wilson, C. M., Civalleri, B., Casassa, S., Maschio, L., Ferrabone, M., De La Pierre, M., D'Arco, P., Noël, Y., Causà, M., Rérat, M. & Kirtman, B. (2014). Int. J. Quantum Chem. 114, 1287-1317.]) energy per formula unit of Na2HC6H5O7(H2O) is −1160.0 eV. The energy per formula unit of Na2HC6H5O7(H2O)1.5 is −1197.9 eV. Calculated in the same way, the energy of an isolated water mol­ecule is −76.4 eV. Thus, the energy of the sesquihydrate is thus 0.23 eV higher than that of the sum of the monohydrate and half a water mol­ecule. The difference is only 5.4 kcal mol−1, so the structures must be considered comparable in energy.

In the extended structure of (II)[link], the NaO6 coordination octa­hedra share corners to form double zigzag chains propagating along the b-axis direction (Figs. 8[link] and 9[link]). Each hydrogen atom of the ammonium ions acts as a donor in a discrete N—H⋯O hydrogen bond (Table 2[link]). The hydroxyl group O17—H18 forms an intra­molecular hydrogen bond to the terminal carboxyl­ate oxygen atom O11. The N—H⋯O hydrogen bond energies were calculated by the correlation of Wheatley & Kaduk (2019[Wheatley, A. M. & Kaduk, J. A. (2019). Powder Diffr. 34, 35-43.]), and the O—H⋯O hydrogen bond energy was calculated by the correlation of Rammohan & Kaduk (2018[Rammohan, A. & Kaduk, J. A. (2018). Acta Cryst. B74, 239-252.]). Despite the similarities in the formulae, the crystal structures of di­ammonium sodium citrate and di­ammonium potassium citrate (Patel et al., 2020[Patel, N. V., Golab, J. T. & Kaduk, J. A. (2020). IUCrData, 5, x200612.]) differ. In the current compound, the NaO6 coordination polyhedra share corners to form zigzag chains, while in di­ammonium potassium citrate the KO7 polyhedra are isolated. The powder patterns (Fig. 10[link]) are not particularly similar, and except for layers containing the ammonium ions (Fig. 11[link]), the structures exhibit many differences.

Table 2
Hydrogen-bond geometry (Å, °) for (II) (DFT)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
O17—H18⋯O11 0.99 1.75 2.630 146
N20—H22⋯O13i 1.04 1.76 2.798 177
N20—H23⋯O16ii 0.95 1.90 2.755 148
N20—H24⋯O14i 1.03 1.82 2.831 170
N20—H25⋯O15iii 1.03 1.82 2.831 167
N21—H26⋯O11 1.04 1.75 2.767 164
N21—H27⋯O12iv 1.04 1.69 2.730 176
N21—H28⋯O12iii 1.03 1.78 2.798 168
N21—H29⋯O14v 1.02 2.13 2.996 141
Symmetry codes: (i) x, y+1, z-1; (ii) [-x+{\script{1\over 2}}, y+{\script{3\over 2}}, -z-{\script{1\over 2}}]; (iii) [-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z-{\script{1\over 2}}]; (iv) x, y+1, z; (v) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}].
[Figure 8]
Figure 8
The crystal structure of (II)[link], viewed down [010].
[Figure 9]
Figure 9
The crystal structure of (II)[link], viewed nearly down the b-axis direction, to better illustrate the chains.
[Figure 10]
Figure 10
Comparison of the X-ray powder diffraction patterns of (II)[link] (green) and (NH4)2KC6H5O7 (black).
[Figure 11]
Figure 11
Comparison of the crystal structures of (II)[link] and (NH4)2KC6H5O7.

4. Database survey

Details of the comprehensive literature search for citrate structures are presented in Rammohan & Kaduk (2018[Rammohan, A. & Kaduk, J. A. (2018). Acta Cryst. B74, 239-252.]). Another pattern of the same sample of `(NH4)Na2C6H5O7' measured using Cu Kα radiation, was indexed on a primitive monoclinic unit cell having a = 16.9845, b = 8.6712, c = 12.2995 Å, β = 90.03°, V = 1800.2 Å3, and Z = 8 using JADE Pro (MDI, 2019[MDI (2019). JADE Pro 7.7. Materials Data, Livermore CA, USA.]). Analysis of the systematic absences using FOX (Favre-Nicolin & Černý, 2002[Favre-Nicolin, V. & Černý, R. (2002). J. Appl. Cryst. 35, 734-743.]) suggested that the space group was Pbca. A reduced cell search in the Cambridge Structural Database (Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) yielded 83 hits but no citrate crystal structures.

The pattern of (NH4)2NaC6H5O7 was indexed with DICVOL14 (Louër & Boultif, 2014[Louër, D. & Boultif, A. (2014). Powder Diffr. 29, S7-S12.]), using the PreDICT inter­face (Blanton et al., 2019[Blanton, J. R., Papoular, R. J. & Louër, D. (2019). Powder Diffr. 34, 233-241.]). Analysis of the systematic absences using EXPO2014 (Altomare et al., 2013[Altomare, A., Cuocci, C., Giacovazzo, C., Moliterni, A., Rizzi, R., Corriero, N. & Falcicchio, A. (2013). J. Appl. Cryst. 46, 1231-1235.]) suggested the space group P21/n, which was confirmed by successful solution and refinement of the structure. A reduced cell search of the cell in the Cambridge Structural Database (Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) resulted in eleven hits, but no citrate structures.

5. Synthesis and crystallization

0.2415 g of (NH4)2CO3 (Aldrich) and 0.5376 g of Na2CO3 (Alfa Aesar) were added to a solution of 1.0162 g citric acid (Sigma–Aldrich) monohydrate in 10 ml of water. After the fizzing subsided, the clear solution was dried at ambient conditions to yield a clear glass. Successive heating at 361, 394, and 410 K did not induce crystallization. The glass was redissolved in 10 ml of water and layered with 40 ml of ethanol. The beaker was covered and left to stand at ambient conditions. After three days, the solvents were blended, but the solution was clear. The beaker was uncovered and after another three days, a white solid was observed at the bottom of the beaker. The solution was deca­nted and the solid was dried at ambient conditions. After one day, the solid was still wet, so it was dried in a 361 K oven for a few minutes to yield a white powder of (I)[link]. The powder pattern was measured from a 0.7 mm diameter capillary specimen on a PANalytical Empyrean diffractometer equipped with an incident beam focusing mirror and an X'Celerator detector, using Mo Kα radiation. The pattern was measured from 1–50° 2θ in 0.010067° steps, counting for four seconds per step.

Di­ammonium sodium citrate was synthesized by dissolving 1.1231 g di­ammonium hydrogen citrate (Fisher Lot #995047) and 0.2713 g sodium carbonate (Alfa Aesar) in ∼6 ml of deionized water. When the fizzing stopped, the clear solution was layered with about 20 ml of acetone and left to stand at ambient conditions. After two days, the solvents had blended and the product was a clear syrup. The syrup was dried at 363 K for three hours to yield a white solid, (II)[link]. The powder pattern was measured from a 0.7 mm diameter capillary specimen on a PANalytical Empyrean diffractometer equipped with an incident beam focusing mirror and an X'Celerator detector, using Mo Kα radiation. The pattern was measured from 1–50° 2θ in 0.010067° steps, counting for four seconds per step.

6. Refinement

Crystal data, data collection and structure refinement details for (I)[link] and (II)[link] are summarized in Table 3[link]. The final Rietveld plots for (I)[link] and (II)[link] are shown in Figs. 12[link] and 13[link], respectively. The structure of (I)[link] was solved using Monte-Carlo simulated annealing techniques as implemented in FOX (Favre-Nicolin & Černý 2002[Favre-Nicolin, V. & Černý, R. (2002). J. Appl. Cryst. 35, 734-743.]). The citrate anion, two sodium atoms and a nitro­gen atom were used as fragments. One of the fifteen runs yielded a cost factor much lower than the others and was used as the basis for refinement.

Table 3
Experimental details

  (I) (II)
Crystal data
Chemical formula 2Na+·C6H7O72−·H2O C6H13N2NaO7
Mr 254.1 248.17
Crystal system, space group Orthorhombic, Pbca Monoclinic, P21/n
Temperature (K) 304 304
a, b, c (Å) 16.9976 (5), 8.6270 (2), 12.2926 (4) 13.0895 (19), 5.6403 (3), 14.822 (2)
α, β, γ (°) 90, 90, 90 90, 111.112 (4), 90
V3) 1802.56 (12) 1020.83 (10)
Z 8 4
Radiation type Kα1,2, λ = 0.70932, 0.71361 Å Kα1,2, λ = 0.70932, 0.71361 Å
μ (mm−1) 0.086 0.104
Specimen shape, size (mm) Cylinder, 12 × 0.7 Cylinder, 12 × 0.7
 
Data collection
Diffractometer PANalytical Empyrean PANalytical Empyrean
Specimen mounting Glass capillary Glass capillary
Data collection mode Transmission Transmission
Scan method Step Step
2θ values (°) 2θmin = 1.019 2θmax = 49.999 2θstep = 0.008 2θmin = 1.019 2θmax = 49.999 2θstep = 0.008
 
Refinement
R factors and goodness of fit Rp = 0.031, Rwp = 0.040, Rexp = 0.020, R(F2) = 0.06046, χ2 = 4.339 Rp = 0.046, Rwp = 0.061, Rexp = 0.020, χ2 = 9.703
No. of parameters 64 75
No. of restraints 29
H-atom treatment Only H-atom displacement parameters refined
Computer programs: FOX (Favre-Nicolin & Černý, 2002[Favre-Nicolin, V. & Černý, R. (2002). J. Appl. Cryst. 35, 734-743.]), GSAS-II (Toby & Von Dreele, 2013[Toby, B. H. & Von Dreele, R. B. (2013). J. Appl. Cryst. 46, 544-549.]), Mercury (Macrae et al., 2020[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.]), DIAMOND (Crystal Impact, 2015[Crystal Impact (2015). DIAMOND. Crystal Impact GbR, Bonn, Germany.]), publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).
[Figure 12]
Figure 12
Rietveld plot for (I)[link]. The blue crosses represent the observed data points, and the green line is the calculated pattern. The cyan curve is the normalized error plot. The vertical scale has been multiplied by a factor of 5× for 2θ > 26.5°. The row of blue tick marks indicates the calculated reflection positions. The red line is the background curve.
[Figure 13]
Figure 13
Rietveld plot for (II)[link]. The blue crosses represent the observed data points, and the green line is the calculated pattern. The cyan curve is the normalized error plot. The row of blue tick marks indicates the calculated reflection positions. The red and cyan tick marks indicate the reflection positions for the di­ammonium sodium citrate and di­ammonium hydrogen citrate impurities. The red line is the background curve.

The structure was refined by the Rietveld method using GSAS-II (Toby & Von Dreele, 2013[Toby, B. H. & Von Dreele, R. B. (2013). J. Appl. Cryst. 46, 544-549.]). In the initial refinement, the Uiso value of the nitro­gen atom refined to a negative value and the nitro­gen atom was 2.4 Å away from the two sodium atoms. Both of these facts suggested that this atom was not the nitro­gen of an ammonium ion, but the oxygen of a water mol­ecule. Thus, the compound was not the intended compound.

The hydrogen atoms were included in fixed positions, which were re-calculated during the course of the refinement using Materials Studio (Dassault Systems, 2019[Dassault Systems (2019). Materials Studio. BIOVIA, San Diego, USA.]). Initial positions of the active hydrogen atoms H18, H22, H23, and H24 were deduced by analysis of potential hydrogen-bonding patterns. The Uiso values of C2, C3, and C4 were constrained to be equal, and those of H7, H8, H9, and H10 were constrained to be 1.3× that of these carbon atoms. The Uiso value of C1, C5, C6, and the oxygen atoms were constrained to be equal, and that of H18 was constrained to be 1.3× this value. The background was described by a four-term shifted Chebyshev polynomial with an extra peak at 12.85° to describe the scattering of the glass capillary.

A density functional geometry optimization was carried out using CRYSTAL14 (Dovesi et al., 2014[Dovesi, R., Orlando, R., Erba, A., Zicovich-Wilson, C. M., Civalleri, B., Casassa, S., Maschio, L., Ferrabone, M., De La Pierre, M., D'Arco, P., Noël, Y., Causà, M., Rérat, M. & Kirtman, B. (2014). Int. J. Quantum Chem. 114, 1287-1317.]). The basis sets for the H, C, N, and O atoms were those of Gatti et al. (1994[Gatti, C., Saunders, V. R. & Roetti, C. (1994). J. Chem. Phys. 101, 10686-10696.]), and the basis set for Na was that of Peintinger et al. (2013[Peintinger, M. F., Oliveira, D. V. & Bredow, T. (2013). J. Comput. Chem. 34, 451-459.]). The calculation was run on eight 2.1 GHz Xeon cores (each with 6 Gb RAM) of a 304-core Dell Linux cluster at IIT, using 8 k-points and the B3LYP functional, and took ∼44 h.

The structure of (II)[link] was solved using DASH (David et al., 2006[David, W. I. F., Shankland, K., van de Streek, J., Pidcock, E., Motherwell, W. D. S. & Cole, J. C. (2006). J. Appl. Cryst. 39, 910-915.]) using a citrate ion, two nitro­gen atoms, and a sodium atom as fragments, along with Mogul Distribution Bias, and <010> preferred orientation. Two of the 100 runs yielded residuals lower than the others. The structure was refined by the Rietveld method using GSAS-II (Toby & Von Dreele, 2013[Toby, B. H. & Von Dreele, R. B. (2013). J. Appl. Cryst. 46, 544-549.]). The hydrogen atoms were included in fixed positions, which were recalculated during the course of the refinement using Materials Studio (Dassault Systems, 2019[Dassault Systems (2019). Materials Studio. BIOVIA, San Diego, USA.]). All C—C and C—O bond distances and all bond angles were restrained based on a Mercury Mogul Geometry Check (Sykes et al., 2011[Sykes, R. A., McCabe, P., Allen, F. H., Battle, G. M., Bruno, I. J. & Wood, P. A. (2011). J. Appl. Cryst. 44, 882-886.]; Bruno et al., 2004[Bruno, I. J., Cole, J. C., Kessler, M., Luo, J., Motherwell, W. D. S., Purkis, L. H., Smith, B. R., Taylor, R., Cooper, R. I., Harris, S. E. & Orpen, A. G. (2004). J. Chem. Inf. Comput. Sci. 44, 2133-2144.]) of the mol­ecule. The Uiso values of the atoms in the central and outer portions of the citrate were constrained to be equal, and the Uiso values of the hydrogen atoms were constrained to be 1.3× those of the atoms to which they are attached. A four-term shifted Chebyschev function was used to model the background, along with a peak at 12.5° to describe the scattering from the capillary and any amorphous component. A single phase model did not account for all of the peaks. We compared those peaks to the patterns of known ammonium and sodium citrates and identified di­ammonium hydrogen citrate (Wheatley & Kaduk, 2019[Wheatley, A. M. & Kaduk, J. A. (2019). Powder Diffr. 34, 35-43.]) and disodium hydrogen citrate monohydrate [i.e., (I)] as impurities, and included them in the refinement. Their concentrations were 8.8% and 4.1% weight percentages respectively.

A density functional geometry optimization (fixed experimental unit cell) was carried out using VASP (Kresse & Furthmüller, 1996[Kresse, G. & Furthmüller, J. (1996). Comput. Mater. Sci. 6, 15-50.]) through the MedeA graphical inter­face (Materials Design, 2016[Materials Design (2016). MedeA 2.20.4. Materials Design Inc. Angel Fire NM, USA.]). The calculation was carried out on 16 2.4 GHz processors (each with 4 GB RAM) of a 64-processor HP Proliant DL580 Generation 7 Linux cluster at North Central College. The calculation used the GGA-PBE functional, a plane wave cutoff energy of 400.0 eV, and a k-point spacing of 0.5 Å−1 leading to a 2 × 3 × 2 mesh, and took 18 h. A single point calculation was done using CRYSTAL14. The basis sets for the H, C, N, and O atoms were those of Gatti et al. (1994[Gatti, C., Saunders, V. R. & Roetti, C. (1994). J. Chem. Phys. 101, 10686-10696.]), and the basis set for Na was that of Peintinger et al. (2013[Peintinger, M. F., Oliveira, D. V. & Bredow, T. (2013). J. Comput. Chem. 34, 451-459.]). The calculation was run on eight 2.1 GHz Xeon cores (each with 6 GB RAM) of a 304-core Dell Linux cluster at IIT, using 8 k-points and the B3LYP functional, and took five days.

Supporting information


Computing details top

Program(s) used to solve structure: FOX for (I); DASH for II-imp2. Program(s) used to refine structure: GSAS-II (Toby & Von Dreele, 2013) for (I). Molecular graphics: Mercury (Macrae et al., 2020), DIAMOND (Crystal Impact, 2015) for (I). Software used to prepare material for publication: publCIF (Westrip, 2010) for (I).

Disodium hydrogen citrate monohydrate (I) top
Crystal data top
2Na+·C6H7O72·H2ODx = 1.873 Mg m3
Mr = 254.1 Kα1,2 radiation, λ = 0.70932, 0.71361 Å
Orthorhombic, PbcaT = 304 K
a = 16.9976 (5) ÅParticle morphology: white powder
b = 8.6270 (2) Åwhite
c = 12.2926 (4) Åcylinder, 12 × 0.7 mm
V = 1802.56 (12) Å3Specimen preparation: Prepared at 298 K
Z = 8
Data collection top
PANalytical Empyrean
diffractometer
Data collection mode: transmission
Radiation source: sealed X-ray tube, PANalytical EmpyreanScan method: step
Specimen mounting: glass capillary2θmin = 1.019°, 2θmax = 49.999°, 2θstep = 0.008°
Refinement top
Least-squares matrix: full64 parameters
Rp = 0.031Only H-atom displacement parameters refined
Rwp = 0.040Weighting scheme based on measured s.u.'s
Rexp = 0.020(Δ/σ)max = 0.015
R(F2) = 0.06046Background function: Background function: "chebyschev" function with 4 terms: 1682(4), -690(8), -285(6), 225(10), Background peak parameters: pos, int, sig, gam: 12.847, 1.463322627e6, 156931.773, 0.100,
5863 data pointsPreferred orientation correction: March-Dollase correction coef. = 1.000 axis = [0, 0, 1]
Profile function: Finger-Cox-Jephcoat function parameters U, V, W, X, Y, SH/L: peak variance(Gauss) = Utan(Th)2+Vtan(Th)+W: peak HW(Lorentz) = X/cos(Th)+Ytan(Th); SH/L = S/L+H/L U, V, W in (centideg)2, X & Y in centideg 19.949, 12.795, 0.000, 2.075, 0.000, 0.032, Crystallite size in microns with "isotropic" model: parameters: Size, G/L mix 1.000, 1.000, Microstrain, "generalized" model (106 * delta Q/Q) parameters: S400, S040, S004, S220, S202, S022, G/L mix 33.849, 17.475, 53.578, 71.795, -10.034, -20.359, 1.000,
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.0915 (5)0.5073 (6)0.9674 (6)0.0210 (9)*
C20.1285 (4)0.3821 (6)1.0372 (4)0.022 (2)*
C30.1338 (3)0.2175 (5)0.9884 (4)0.0216*
C40.1952 (4)0.2166 (6)0.8963 (5)0.0216*
C50.2074 (4)0.0741 (9)0.8266 (6)0.0210*
C60.1579 (4)0.1002 (7)1.0781 (5)0.0210*
H70.102060.377941.105120.0280*
H80.179060.415921.048050.0280*
H90.183790.303610.843870.0280*
H100.246190.244610.929930.0280*
O110.1057 (3)0.6434 (7)0.9979 (5)0.0210*
O120.0560 (4)0.4657 (7)0.8835 (4)0.0210*
O130.2679 (4)0.0826 (7)0.7648 (5)0.0210*
O140.1527 (4)0.0242 (7)0.8224 (4)0.0210*
O150.2199 (3)0.1288 (7)1.1304 (5)0.0210*
O160.1154 (3)0.0196 (6)1.0820 (4)0.0210*
O170.0586 (3)0.1802 (6)0.9453 (4)0.0210*
O190.4752 (4)0.2784 (7)0.2712 (5)0.010 (2)*
Na200.0494 (2)0.8835 (5)0.9277 (3)0.0371 (11)*
Na210.6503 (3)0.7676 (6)0.8258 (3)0.0371*
H180.057600.275300.924100.0273*
H220.465500.361600.306500.048*
H230.499000.290900.209700.048*
H240.272000.010000.718500.027*
Geometric parameters (Å, º) top
Na20—O112.440 (8)C4—C51.512 (2)
Na20—O14i2.323 (6)C4—H91.008 (7)
Na20—O16i2.358 (6)C4—H100.990 (7)
Na20—O17i2.573 (6)C5—C41.512 (2)
Na20—O17ii2.470 (5)C5—O131.280 (6)
Na20—O19iii2.414 (7)C5—O141.259 (6)
Na21—O11iv2.421 (6)C6—C31.553 (2)
Na21—O13v2.392 (8)C6—O151.258 (4)
Na21—O14vi2.559 (7)C6—O161.263 (5)
Na21—O15vii2.441 (7)H7—C20.949 (7)
Na21—O16viii2.492 (6)H7—H81.5208
Na21—O19ix2.475 (6)H8—C20.918 (7)
C1—C21.515 (2)H8—H71.5208
C1—O111.256 (6)H9—C41.008 (7)
C1—O121.248 (6)H9—H101.5821
C2—C11.515 (2)H10—C40.990 (7)
C2—C31.544 (2)H10—H91.5821
C2—H70.949 (7)O11—Na21x2.421 (6)
C2—H80.918 (7)O13—Na21xi2.392 (8)
C3—C21.544 (2)O13—H240.849 (5)
C3—C41.540 (2)O17—H180.861 (5)
C3—C61.553 (2)O19—H220.855 (6)
C3—O171.421 (2)O19—H230.864 (6)
C4—C31.540 (2)
C2—C1—O11114.7 (4)C5—C4—H9105.6 (7)
C2—C1—O12117.6 (4)C3—C4—H10106.5 (5)
O11—C1—O12127.4 (4)C5—C4—H10108.4 (6)
C1—C2—C3117.4 (3)H9—C4—H10104.7 (5)
C1—C2—H7109.2 (6)C4—C5—O13113.5 (4)
C3—C2—H7109.6 (5)C4—C5—O14118.0 (4)
C1—C2—H8104.1 (6)O13—C5—O14127.4 (4)
C3—C2—H8107.1 (5)C3—C6—O15117.2 (4)
H7—C2—H8109.1 (5)C3—C6—O16114.2 (4)
C2—C3—C4109.3 (4)O15—C6—O16128.3 (4)
C2—C3—C6109.8 (4)C5—O13—H24115.0 (6)
C4—C3—C6109.9 (4)C5—O14—Na20xii140.0 (5)
C2—C3—O17107.5 (4)C6—O16—Na20xii122.2 (5)
C4—C3—O17109.6 (4)C3—O17—H1885.0 (4)
C6—C3—O17110.8 (3)H22—O19—H23115.4 (7)
C3—C4—C5120.9 (4)O14i—Na20—O16i88.1 (2)
C3—C4—H9109.6 (5)
Symmetry codes: (i) x, y+1, z; (ii) x, y+1, z+2; (iii) x+1/2, y+1, z+1/2; (iv) x+3/2, y+5/2, z+2; (v) x+1, y+3/2, z+5/2; (vi) x+3/2, y+1, z+5/2; (vii) x+1, y+1, z+2; (viii) x+3/2, y+3/2, z+2; (ix) x+1, y+1, z+1; (x) x+1/2, y+5/2, z+2; (xi) x+1, y+1/2, z+5/2; (xii) x, y1, z.
(I_DFT) top
Crystal data top
C6H8Na2O8b = 8.6270 Å
Mr = 254.1c = 12.2926 Å
Orthorhombic, PbcaV = 1808.6 Å3
a = 16.9976 ÅZ = 8
Data collection top
h = l =
k =
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.098490.514070.975760.02100*
C20.132660.383021.044500.02160*
C30.133370.222270.989980.02160*
C40.195150.221630.898900.02160*
C50.203060.079520.828600.02100*
C60.153620.099131.075870.02100*
H70.097290.377271.118440.02800*
H80.191890.415221.068740.02800*
H90.181410.316090.842930.02800*
H100.253080.245970.932820.02800*
O110.112140.650911.004680.02100*
O120.056440.476980.893710.02100*
O130.268420.081790.770830.02100*
O140.155250.027320.821090.02100*
O150.215610.125441.132140.02100*
O160.110760.017341.086350.02100*
O170.055760.189230.947960.02100*
H180.038630.291920.919250.02730*
O190.473990.279630.274170.01010*
Na200.049090.881300.928150.03710*
Na210.648390.762110.823850.03710*
H220.463900.378860.314160.04800*
H230.512990.301710.219050.04800*
H240.273500.010330.713770.02700*
Bond lengths (Å) top
C1—C21.526C4—H101.090
C1—O111.255C5—O131.319
C1—O121.277C5—O141.232
C2—C31.540C6—O151.281
C2—H71.091C6—O161.248
C2—H81.086O13—H241.064
C3—C41.535O17—H180.997
C3—C61.537O19—H221.002
C3—O171.445O19—H230.967
C4—C51.506H24—O131.064
C4—H91.092
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O13—H24···O15i1.061.422.485175
O17—H18···O121.001.622.578179
O19—H23···O17ii0.972.183.076154
O19—H22···O12iii1.001.622.615172
Symmetry codes: (i) x+1/2, y, z1/2; (ii) x+1/2, y+1/2, z+1; (iii) x+1/2, y+1, z1/2.
(II) top
Crystal data top
C6H13N2NaO7β = 111.112 (4)°
Mr = 248.17V = 1020.83 (10) Å3
Monoclinic, P21/nZ = 4
a = 13.0895 (19) ÅDx = 1.615 Mg m3
b = 5.6403 (3) ÅT = 304 K
c = 14.822 (2) Åcylinder, 12 × 0.7 mm
Data collection top
PANalytical Empyrean
diffractometer
Data collection mode: transmission
Specimen mounting: glass capillaryScan method: step
Refinement top
Profile function: Crystallite size in microns with "isotropic" model: parameters: Size, G/L mix 3.7(16), 1.000, Microstrain, "isotropic" model (106 * delta Q/Q) parameters: Mustrain, G/L mix 100.000, 1.000,Preferred orientation correction: Simple spherical harmonic correction Order = 2 Coefficients: 0:0:C(2,-2) = 0.0720; 0:0:C(2,0) = 0.0861; 0:0:C(2,2) = -0.0293
29 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.3245 (9)0.1347 (13)0.0540 (4)0.0376 (19)*
C20.4091 (8)0.2749 (16)0.0265 (4)0.025 (5)*
C30.4171 (4)0.2134 (12)0.1306 (4)0.025*
C40.5123 (6)0.3478 (19)0.2064 (4)0.025*
C50.5063 (11)0.3558 (15)0.3071 (5)0.0376*
C60.3075 (6)0.2837 (13)0.1436 (9)0.0376*
H70.398500.429950.017720.032*
H80.476670.219100.028370.032*
H90.511950.494680.188440.032*
H100.575510.248720.211070.032*
O110.3120 (8)0.0798 (12)0.0330 (6)0.0376*
O120.2890 (9)0.2373 (16)0.1363 (5)0.0376*
O130.5086 (9)0.5624 (16)0.3416 (6)0.0376*
O140.5043 (9)0.1556 (18)0.3462 (6)0.0376*
O150.2566 (7)0.1144 (17)0.1649 (8)0.0376*
O160.2843 (7)0.5035 (14)0.1339 (9)0.0376*
O170.4375 (7)0.0334 (13)0.1467 (7)0.0376*
H180.400000.100000.100000.0489*
Na190.6357 (6)0.1785 (14)0.7351 (6)0.033 (3)*
N200.3773 (10)0.727 (2)0.5343 (9)0.025 (5)*
N210.1886 (10)0.361 (3)0.1861 (9)0.025*
H220.424310.648580.535060.033*
H230.339150.830220.451870.033*
H240.443130.752290.423620.033*
H250.343920.555140.423100.033*
H260.222510.237590.865210.033*
H270.226670.524820.836770.033*
H280.178840.326890.746750.033*
H290.104410.394770.815680.033*
Geometric parameters (Å, º) top
C1—C21.524 (3)O16—C61.272 (3)
C1—O111.275 (3)O16—Na19iii2.572 (12)
C1—O121.277 (3)O17—C31.422 (3)
C2—C11.524 (3)O17—H180.785 (10)
C2—C31.549 (3)O17—Na19iv2.422 (10)
C2—H70.887 (10)H18—O170.785 (10)
C2—H80.930 (11)Na19—O13iii2.335 (12)
C3—C21.549 (3)Na19—O14iv2.602 (15)
C3—C41.543 (3)Na19—O15iv2.325 (11)
C3—C61.565 (3)Na19—O15vi2.477 (11)
C3—O171.422 (3)Na19—O16iii2.572 (12)
C3—H24i1.189 (5)Na19—O17iv2.422 (10)
C4—C31.543 (3)N20—H22ii0.881 (13)
C4—C51.524 (3)N20—H23ii0.963 (13)
C4—H90.869 (10)N20—H25ii1.077 (12)
C4—H100.980 (10)N20—H29vii1.133 (12)
C5—C41.524 (3)N21—H26ii1.015 (12)
C5—O131.268 (3)N21—H27ii1.107 (14)
C5—O141.274 (3)N21—H28ii1.104 (13)
C6—C31.565 (3)H22—N20viii0.881 (13)
C6—O151.268 (3)H22—H231.6507
C6—O161.272 (3)H22—H251.5431
C6—H24i0.678 (7)H22—H29ix1.1533
H7—C20.887 (10)H23—N20viii0.963 (13)
H7—H81.5394H23—H221.6507
H8—C20.930 (11)H23—H251.3917
H8—H71.5394H23—H29ix1.0358
H9—C40.869 (10)H24—C3x1.189 (5)
H9—H101.5900H24—C6x0.678 (7)
H10—C40.980 (10)H24—O15x1.262 (5)
H10—H91.5900H25—N20viii1.077 (12)
O11—C11.275 (3)H25—H221.5431
O11—H27ii1.666 (7)H25—H231.3917
O12—C11.277 (3)H26—N21viii1.015 (12)
O13—C51.268 (3)H27—O11viii1.666 (7)
O13—Na19iii2.335 (12)H27—N21viii1.107 (14)
O14—C51.274 (3)H27—H281.2772
O14—Na19iv2.602 (15)H28—N21viii1.104 (13)
O15—C61.268 (3)H28—H271.2772
O15—Na19iv2.325 (11)H29—N20xi1.133 (12)
O15—Na19v2.477 (11)H29—H22xii1.1533
O15—H24i1.262 (5)H29—H23xii1.0358
C2—C1—O11115.0 (3)O16—C6—H24i152.5 (12)
C2—C1—O12115.1 (3)C5—O13—Na19iii118.8 (10)
O11—C1—O12129.0 (3)C6—O15—Na19iv116.2 (6)
C1—C2—C3115.7 (3)C6—O15—H24i31.1 (3)
C1—C2—H7111.5 (7)Na19iv—O15—H24i96.1 (5)
C3—C2—H7108.5 (6)C3—O17—H18107.5 (7)
C1—C2—H8105.2 (8)O13iii—Na19—O15iv162.5 (5)
C3—C2—H899.9 (6)H22ii—N20—H23ii127.1 (13)
H7—C2—H8115.7 (6)H22ii—N20—H25ii103.6 (13)
C2—C3—C4111.2 (3)H23ii—N20—H25ii85.9 (10)
C2—C3—O17109.1 (3)H22ii—N20—H29vii68.6 (8)
C4—C3—O17107.8 (3)H23ii—N20—H29vii58.6 (7)
C2—C3—H24i109.1 (4)H25ii—N20—H29vii98.2 (10)
C4—C3—H24i127.4 (4)H26ii—N21—H27ii108.3 (13)
O17—C3—H24i89.1 (4)H26ii—N21—H28ii106.3 (13)
C3—C4—C5114.5 (3)H27ii—N21—H28ii70.6 (9)
C3—C4—H9109.4 (6)N20viii—H22—H29ix66.1 (8)
C5—C4—H9106.0 (6)N20viii—H23—H29ix69.0 (7)
C3—C4—H10102.2 (6)C3x—H24—C6x110.9 (7)
C5—C4—H10106.7 (7)C3x—H24—O15x156.2 (6)
H9—C4—H10118.4 (7)C6x—H24—O15x75.0 (4)
C4—C5—O13114.8 (3)N21viii—H27—H2854.6 (7)
C4—C5—O14115.9 (3)N21viii—H28—H2754.8 (7)
O13—C5—O14129.2 (3)N20xi—H29—H22xii45.3 (7)
O15—C6—O16129.5 (3)N20xi—H29—H23xii52.5 (7)
O15—C6—H24i74.0 (5)H22xii—H29—H23xii97.74
Symmetry codes: (i) x, y1, z; (ii) x, y, z1; (iii) x+1, y1, z+1; (iv) x+1, y, z+1; (v) x+1/2, y+1/2, z+1/2; (vi) x+3/2, y+1/2, z+3/2; (vii) x+1/2, y+1/2, z1/2; (viii) x, y, z+1; (ix) x+1/2, y+1/2, z+1/2; (x) x, y+1, z; (xi) x+1/2, y1/2, z1/2; (xii) x+1/2, y1/2, z+1/2.
(II_imp1) top
Crystal data top
C6H8Na2O8c = 12.304 (9) Å
Mr = 254.1V = 1808.2 (16) Å3
Orthorhombic, PbcaZ = 8
a = 17.204 (13) ÅDx = 1.867 Mg m3
b = 8.542 (7) ÅT = 304 K
Refinement top
Profile function: Crystallite size in microns with "isotropic" model: parameters: Size, G/L mix 1.000, 1.000, Microstrain, "isotropic" model (106 * delta Q/Q) parameters: Mustrain, G/L mix 1000.000, 1.000,Preferred orientation correction: March-Dollase correction coef. = 1.000 axis = [0, 0, 1]
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.205300.076200.169300.018*
C20.194200.220000.099800.018*
C30.131120.217700.010700.018*
C40.129600.379300.041700.018*
C50.093000.507100.028300.018*
C60.157100.097900.076300.018*
H70.248190.258220.072040.024*
H80.182360.304400.151850.024*
H90.178630.417700.058100.024*
H100.094790.375060.099860.024*
O110.152100.023100.179600.018*
O120.265100.082800.229800.018*
O130.106500.644900.003200.018*
O140.057700.469200.112700.018*
O150.116040.021300.083800.018*
O160.217780.127600.128900.018*
O170.058180.176600.050800.018*
H180.058000.270500.077400.024*
O190.028100.723300.227400.025*
Na200.651960.733300.672300.032*
Na210.950100.117400.928640.032*
H220.033700.638600.194100.039*
H230.000300.707800.290400.039*
H240.271700.008200.279200.025*
Geometric parameters (Å, º) top
C1—C21.5088O14—H181.752
C1—O111.2543O15—C61.2427
C1—O121.2711O15—Na20v2.4417
C2—C11.5088O15—Na21ii2.3693
C2—C31.5427O16—C61.2542
C2—H71.0421O16—Na20vi2.4743
C2—H80.9856O16—H24vii1.6300
C3—C21.5427O17—C31.3933
C3—C41.5238O17—H180.8663
C3—C61.5469O17—Na21viii2.4438
C3—O171.3933O17—Na21ii2.5281
C3—H181.5683H18—C31.5683
C4—C31.5238H18—O141.752
C4—C51.5265H18—O170.8663
C4—H90.9273O19—Na20ix2.4902
C4—H100.9339O19—Na21iii2.3830
C5—C41.5265O19—H220.8370
C5—O131.2389O19—H230.9204
C5—O141.2458Na20—O11x2.5583
C6—C31.5469Na20—O12iii2.4402
C6—O151.2427Na20—O13xi2.4176
C6—O161.2542Na20—O15xii2.4417
H7—C21.0421Na20—O16xiii2.4743
H7—H81.5500Na20—O19xiv2.4902
H8—C20.9856Na21—O11ii2.3482
H8—H71.5500Na21—O13iii2.4030
H9—C40.9273Na21—O15ii2.3693
H9—H101.5739Na21—O17xv2.4438
H10—C40.9339Na21—O17ii2.5281
H10—H91.5739Na21—O19iii2.3830
O11—C11.2543Na21—Na21xvi3.1709
O11—Na20i2.5583Na21—H22iii2.5890
O11—Na21ii2.3482H22—O190.8370
O12—C11.2711H22—Na21iii2.5890
O12—Na20iii2.4402H22—H231.4435
O12—H240.8879H23—O190.9204
O13—C51.2389H23—H221.4435
O13—Na20iv2.4176H24—O120.8879
O13—Na21iii2.4030H24—O16xvii1.6300
O14—C51.2458
C2—C1—O11121.028C3—C4—H10107.465
C2—C1—O12113.469C5—C4—H10101.28
O11—C1—O12124.153H9—C4—H10115.487
C1—C2—C3118.779C4—C5—O13117.484
C1—C2—H7109.148C4—C5—O14119.051
C3—C2—H7113.456O13—C5—O14123.099
C1—C2—H8104.677C3—C6—O15115.416
C3—C2—H8109.009C3—C6—O16117.631
H7—C2—H899.673O15—C6—O16126.91
C2—C3—C4107.531C1—O11—Na21ii136.141
C2—C3—C6107.275C1—O12—H24118.201
C4—C3—C6108.146C6—O15—Na21ii119.805
C2—C3—O17112.649C3—O17—H1884.475
C4—C3—O17111.263H22—O19—H23110.349
C6—C3—O17109.791O11ii—Na21—O15ii88.773
C3—C4—C5114.595O11ii—Na21—Na21xvi120.17
C3—C4—H9113.387O15ii—Na21—Na21xvi66.085
C5—C4—H9104.184
Symmetry codes: (i) x+1/2, y+3/2, z+1; (ii) x+1, y, z+1; (iii) x+1, y+1, z+1; (iv) x+1/2, y, z+3/2; (v) x+1/2, y1, z+3/2; (vi) x+1, y+1/2, z+3/2; (vii) x+1/2, y, z1/2; (viii) x1, y, z1; (ix) x+1/2, y+5/2, z+1; (x) x+3/2, y+3/2, z+1; (xi) x+3/2, y, z+3/2; (xii) x+3/2, y+1, z+3/2; (xiii) x+1, y+3/2, z+3/2; (xiv) x+3/2, y+5/2, z+1; (xv) x+1, y, z+1; (xvi) x+2, y, z+2; (xvii) x+1/2, y, z+1/2.
Diammonium sodium citrate (II-imp2) top
Crystal data top
NH4+·2Na+·C6H5O73V = 983.0 (3) Å3
Mr = 227.19Z = 4
Orthorhombic, PnmaDx = 1.535 Mg m3
a = 10.789 (3) ÅT = 304 K
b = 14.761 (4) ÅParticle morphology: white powder
c = 6.1723 (19) Å
Refinement top
Profile function: Crystallite size in microns with "isotropic" model: parameters: Size, G/L mix 10(11), 1.000, Microstrain, "isotropic" model (106 * delta Q/Q) parameters: Mustrain, G/L mix 1000.000, 1.000,Preferred orientation correction: March-Dollase correction coef. = 1.000 axis = [0, 0, 1]
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.553110.051700.124000.030*
O20.390690.042910.343220.030*
O30.363550.250000.036100.030*
O40.571350.250000.045600.030*
O50.346250.250000.378100.030*
H10.305000.250000.263000.039*
C10.487480.079470.283400.030*
C20.536010.164540.390300.030*
H20.625600.170800.362000.039*
H30.520400.162900.542000.039*
C30.469850.250000.049600.030*
C40.470410.250000.301900.030*
N10.244460.113950.681500.030*
H40.203000.068200.746000.039*
H50.182000.150800.624000.039*
H60.292000.146800.786000.039*
H70.298000.094200.567000.039*
H8?0.503000.015000.030000.039*
Geometric parameters (Å, º) top
O1—C11.2796C4—C2ii1.5460
O1—H8?0.9604C4—C31.5573
O1—H8?i1.4965N1—H40.9026
O2—C11.2321N1—H50.9359
O3—C31.2630N1—H60.9562
O4—C31.2428N1—H70.9582
O5—H10.8383H4—N10.9026
O5—C41.4198H4—H51.4509
H1—O50.8383H4—H61.5262
C1—O11.2796H4—H71.5552
C1—O21.2321H5—N10.9359
C1—C21.5121H5—H41.4509
C2—C11.5121H5—H61.5530
C2—H20.9866H5—H71.5454
C2—H30.9517H6—N10.9562
C2—C41.5460H6—H41.5262
H2—C20.9866H6—H51.5530
H2—H31.5926H6—H71.5602
H3—C20.9517H7—N10.9582
H3—H21.5926H7—H41.5552
C3—O31.2630H7—H51.5454
C3—O41.2428H7—H61.5602
C3—C41.5573H8?—O10.9604
C4—O51.4198H8?—O1i1.4965
C4—C21.5460H8?—H8?i0.5809
C1—O1—H8?109.49O5—C4—C2108.365
H1—O5—C4102.72O5—C4—C2ii108.365
O1—C1—O2123.995C2—C4—C2ii109.369
O1—C1—C2114.199O5—C4—C3109.123
O2—C1—C2121.768C2—C4—C3110.776
C1—C2—H2109.864C2ii—C4—C3110.776
C1—C2—H3110.299H4—N1—H5104.196
H2—C2—H3110.485H4—N1—H6110.351
C1—C2—C4111.413H5—N1—H6110.324
H2—C2—C4108.038H4—N1—H7113.358
H3—C2—C4106.677H5—N1—H7109.343
O3—C3—O4127.025H6—N1—H7109.173
O3—C3—C4114.982O1—H8?—H8?i151.385
O4—C3—C4117.994
Symmetry codes: (i) x+1, y, z; (ii) x, y+1/2, z.
(II_DFT) top
Crystal data top
C6H13N2NaO7c = 14.809688 Å
Mr = 248.17β = 111.1167°
Monoclinic, P21/nV = 1018.21 Å3
a = 13.077726 ÅZ = 4
b = 5.635725 Å
Data collection top
h = l =
k =
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.3349550.1258590.0532930.0368
C20.4137010.2733630.0284150.025
C30.4178370.2123400.1309130.025
C40.5136600.3472230.2053160.025
C50.5102600.3521840.3071730.0368
C60.3098180.2929880.1426070.0368
H70.3940120.4600320.0134630.032
H80.4953280.2443320.0259800.032
H90.5143800.5286200.1808110.032
H100.5892510.2619370.2074080.032
O110.3125850.0836900.0352690.0368
O120.2975730.2176420.1368190.0368
O130.5089390.5543380.3446140.0368
O140.5064940.1573560.3489630.0368
O150.2511390.1412270.1646510.0368
O160.2885730.5112810.1315370.0368
O170.4366590.0369630.1483710.0368
H180.3988650.1155380.0886780.048
Na190.6365910.1800230.7388320.043
N200.3866500.6975900.5369660.018
H220.4243180.6485830.4649440.023
H230.3391520.8302210.5481350.023
H240.4431350.7522930.5763880.023
H250.3439240.5551440.5769060.023
N210.1819570.3686640.1844150.018
H260.2225150.2375900.1347970.023
H270.2266740.5248210.1632330.023
H280.1788430.3268920.2532560.023
H290.1044170.3947720.1843200.023
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O17—H18···O110.991.752.630146
N20—H22···O13i1.041.762.798177
N20—H23···O16ii0.951.902.755148
N20—H24···O14i1.031.822.831170
N20—H25···O15iii1.031.822.831167
N21—H26···O111.041.752.767164
N21—H27···O12iv1.041.692.730176
N21—H28···O12iii1.031.782.798168
N21—H29···O14v1.022.132.996141
Symmetry codes: (i) x, y+1, z1; (ii) x+1/2, y+3/2, z1/2; (iii) x+1/2, y+1/2, z1/2; (iv) x, y+1, z; (v) x1/2, y+1/2, z1/2.
 

Acknowledgements

We thank North Central College for allowing us the space and resources to pursue this research project. We also thank the Illinois Mathematics and Science Academy for offering us the opportunity to work on this project. We thank Andrey Rogachev for the use of computing resources at the Illinois Institute of Technology.

References

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