research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 82| Part 6| June 2026| Pages 707-711
https://doi.org/10.1107/S2056989026005190

Levosimendan Form I, C14H12N6O

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Jacob K. Salazar,a James A. Kaduk,b* Anja Dosenc and Thomas N. Blantonc

aNorth Central College, Department of Chemistry, 131 S. Loomis St., Naperville IL 60540, USA, bNorth Central College, Department of Physics, 131 S. Loomis St., Naperville IL 60540, USA, and cICDD, 12 Campus Blvd., Newtown Square PA 19073-3273, USA
*Correspondence e-mail: [email protected]

Edited by J. M. Delgado, Universidad de Los Andes, Venezuela (Received 20 April 2026; accepted 17 May 2026; online 22 May 2026)

The crystal structure of levosimendan Form I [systematic name: 2-({4-[(4R)-4-methyl-6-oxo-4,5-di­hydro-1H-pyridazin-3-yl]phen­yl}hydrazinyl­idene)propanedi­nitrile], C14H12N6O, has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Levosimendan Form I crystallizes in space group P212121 (#19). The crystal structure is characterized by nearly parallel stacking of the mol­ecules parallel to the bc plane. N—H⋯O and N—H⋯N hydrogen bonds link the mol­ecules within the layers, with graph sets C(11) and C(13) and larger patterns.

CCDC references: 2554934; 2554935; 2554933

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1. Chemical context

Levosimendan (marketed as Simdax®) is used to treat congestive heart failure. It functions as a calcium sensitizer inotrope medication used to control the force of heart contractions. The systematic name (CAS Registry Number 141505-33-1) is 2-[[4-[(4R)-4-methyl-6-oxo-4,5-di­hydro-1H-pyridazin-3-yl]phen­yl]hydrazinyl­idene]propanedi­nitrile.

[Scheme 1]

Compositions containing crystalline levosimendan Form I are claimed in US Patent 6,355,269 B1 (Backman et al., 2002View full citation; Orion Corporation), and powder data for pure Form I are provided. A process for preparing levosimendan Form II is claimed in European Patent Application EP 3,424,908 A1 (Singhania, 2017View full citation; Melody Healthcare Pvt. Ltd.), and powder data are provided. However, crystal structure data are not reported.

This work was carried out as part of a project (Kaduk et al., 2014View full citation) to determine the crystal structures of large-volume commercial pharmaceuticals, and include high-quality powder diffraction data for them in the Powder Diffraction File (Kabekkodu et al., 2024View full citation).

2. Structural commentary

The synchrotron pattern of levosimendan is similar enough to that reported by Backman et al. (2002View full citation) for Form I (Fig. 1[link]) to conclude that they represent the same material. The patent pattern exhibits significant displacement/transparency peak position errors, as well as preferred orientation.

[Figure 1]
Figure 1
Comparison of the synchrotron pattern of levosimendan Form I (black) from this study to the laboratory XRD pattern reported by Backman et al. (2002View full citation; green). The patent pattern (measured using Cu Kα radiation) was digitized using UN-SCAN-IT (Silk Scientific, 2013View full citation) and converted to the synchrotron wavelength of 0.4687342 Å using JADE Pro (MDI, 2025View full citation). Image generated using JADE Pro (MDI, 2025View full citation).

The root-mean-square difference of the non-H atoms in the Rietveld-refined and VASP-optimized structures of levosimendan, calculated using the Mercury CSD-Materials/Search/Crystal Packing Similarity tool (Macrae et al., 2020View full citation) is 0.093 Å (Fig. 2[link]); the structures are essentially identical. The root-mean-square Cartesian displacement of the non-H atoms in the refined and optimized structures, calculated using the Mercury Calculate/Mol­ecule Overlay tool, is 0.083 Å (Fig. 3[link]); the maximum difference is 0.167 Å, at N6. The agreements are within the normal range for correct structures (van de Streek & Neumann, 2014View full citation). The asymmetric unit is illustrated in Fig. 4[link]. The remaining discussion will emphasize the VASP-optimized structure.

[Figure 2]
Figure 2
Comparison of the Rietveld-refined (colored by atom type) and VASP-optimized (pale green) structures of levosimendan Form I, calculated using the Mercury CSD-Materials/Search/Crystal Packing Similarity tool. The root-mean-square Cartesian displacement is 0.093 Å. Image generated using Mercury (Macrae et al., 2020View full citation).
[Figure 3]
Figure 3
Comparison of the refined structure of levosimendan Form I (red) to the VASP-optimized structure (blue). The comparison was generated using the Mercury Calculate/Mol­ecule Overlay tool; the r.m.s. difference is 0.083 Å. Image generated using Mercury (Macrae et al., 2020View full citation).
[Figure 4]
Figure 4
The asymmetric unit of levosimendan, with the atom numbering. The atoms are represented by 50% probability spheroids. Image generated using Mercury (Macrae et al., 2020View full citation).

All of the bond distances, bond angles, and torsion angles fall within the normal ranges indicated by a Mercury Mogul Geometry check (Macrae et al., 2020View full citation). Quantum chemical geometry optimization of the isolated levosimendan mol­ecule (DFT/B3LYP/6-31G*/water) using Spartan '24 (Wavefunction, 2025View full citation) indicated that the observed conformation is 2.3 kcal mol−1 higher in energy than a local minimum, which has a very similar conformation. The global minimum-energy conformation is 3.3 kcal mol−1 lower in energy, but is folded on itself. Inter­molecular inter­actions are thus important to determine the observed solid-state conformation.

3. Supra­molecular features

A view of the crystal structure down the short a-axis (Fig. 5[link]) shows the mol­ecules reasonably clearly, but obscures the nearly parallel stacking of the mol­ecules (Fig. 6[link]) parallel to the bc plane. N—H⋯O and N—H⋯N hydrogen bonds (Table 1[link]) link the mol­ecules within the layers. The mean plane of the mol­ecules is approximately (5Mathematical equationMathematical equation). The Mercury Aromatics Analyser indicates two strong (d = 4.42 Å) inter­actions between the phenyl rings.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A Mulliken overlap
N4—H33⋯O1 1.045 1.826 2.813 156.1 0.058
N4—H33⋯C21 1.045 2.566 2.858 95.2 0.011
N3—H28⋯N6 1.031 1.948 2.947 162.3 0.048
C16—H31⋯O1 1.089 2.170 3.049 136.0 0.031
C15—H30⋯N2 1.090 2.502 2.821 95.3 0.014
C9—H24⋯N7 1.097 2.346 3.366 153.9 0.016
[Figure 5]
Figure 5
Crystal structure of levosimendan, viewed down the a-axis. Image generated using DIAMOND (Crystal Impact, 2025View full citation).
[Figure 6]
Figure 6
Crystal structure of levosimendan, viewed down the b axis. Image generated using DIAMOND (Crystal Impact, 2025View full citation).

Analysis of the contributions to the total crystal energy of the structure using the Forcite module of Materials Studio (Dassault Systèmes, 2025View full citation) indicated that bond, angle, and torsion distortion terms contribute about equally to the intra­molecular energy. The inter­molecular energy is dominated by van der Waals attractions, which in this force field based analysis include hydrogen bonds. The hydrogen bonds are better discussed using the results of the DFT calculation.

A strong N4—H33⋯O1 hydrogen bond (Table 1[link]) links an amino group and the carbonyl group. The energy of this hydrogen bond (5.6 kcal mol−1) was calculated using the correlation of Wheatley & Kaduk (2019View full citation). An N3—H28⋯N6 hydrogen bond links the other amino group with one of the cyano groups. These two classical hydrogen bonds link the mol­ecules within the layers (Fig. 7[link]). The graph sets (Etter, 1990View full citation; Bernstein et al., 1995View full citation; Motherwell et al., 2000View full citation) of these two hydrogen bonds are C(11) and C(13), and they form larger patterns with graph sets C22(10), C22(24) and higher. Intra- and inter­molecular C—H⋯O, C—H⋯N, and C—H⋯C hydrogen bonds also contribute to the lattice energy.

[Figure 7]
Figure 7
The hydrogen bonds in the bc plane of the layers in levosimendan Form I. Image generated using Mercury (Macrae et al., 2020View full citation). The red dashed lines indicate hydrogen bonds generated automatically using the definitions in Mercury, and the cyan dashed lines indicate hydrogen bonds generated manually using the Mercury Expand Contacts tool.

The volume enclosed by the Hirshfeld surface of levosimendan (Fig. 8[link]; Hirshfeld, 1977View full citation; Spackman et al., 2021View full citation) is 346.56 Å3, 97.93% of 1/4 of the unit-cell volume. The packing density is thus typical. Surprisingly, the hydrogen bonds are not prominent among the close contacts (red in Fig. 8[link]). The volume/non-hydrogen atom is smaller than normal, at 16.8 Å3.

[Figure 8]
Figure 8
The Hirshfeld surface of levosimendan Form I. Inter­molecular contacts longer than the sums of the van der Waals radii are colored blue, and contacts shorter than the sums of the radii are colored red. Contacts equal to the sums of radii are white. Image generated using CrystalExplorer (Spackman et al., 2021View full citation).

The Bravais–Friedel–Donnay–Harker (Bravais, 1866View full citation; Friedel, 1907View full citation; Donnay & Harker, 1937View full citation) algorithm suggests that we might expect elongated morphology for levosimendan, with [100] as the long axis. A second-order spherical harmonic model for preferred orientation was included. The texture index was 1.002, indicating that the preferred orientation was negligible in this rotated capillary specimen.

4. Database survey

A name search in the Powder Diffraction File (Kabekkodu et al., 2024View full citation) yielded no hits. A reduced cell search in the Cambridge Structural Database (CSD Version 2026.1.0; Groom et al., 2016View full citation), combined with the chemistry C, H, N, and O only, yielded 30 hits, but no structures of levosimendan or its derivatives. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®)

5. Synthesis and crystallization

Levosimendan was a commercial reagent, purchased from TargetMol (Batch #120246), and was used as received.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. The bright-orange powder was packed into a 1.5 mm diameter Kapton capillary, and rotated during the measurement at ∼50 Hz. The powder pattern was measured at 295 K at beam line 11-BM (Lee et al., 2008View full citation; Wang et al., 2008View full citation; Antao et al., 2008View full citation) of the Advanced Photon Source at Argonne National Laboratory using a wavelength of 0.4687342 Å from 0.5–50° in 2θ with a step size of 0.001° and a counting time of 0.1 sec/step. The high-resolution powder diffraction data were collected using twelve silicon crystal analyzers that allow for high angular resolution, high precision, and accurate peak positions. A mixture of silicon (NIST SRM 640c) and alumina (NIST SRM 676a) standards (ratio Al2O3:Si = 2:1 by weight) was used to calibrate the instrument and refine the monochromatic wavelength used in the experiment.

Table 2
Experimental details

  levosimendan
Crystal data
Chemical formula C14H12N6O
Mr 280.29
Crystal system, space group Orthorhombic, P212121
Temperature (K) 295
a, b, c (Å) 6.88117 (5), 10.29085 (14), 19.9896 (2)
V (Å3) 1415.53 (2)
Z 4
Radiation type Synchrotron, λ = 0.46873 Å
μ (mm−1) ?
Specimen shape, size (mm) Cylinder, 2 × 1.5
 
Data collection
Diffractometer 11-BM, APS
Specimen mounting Kapton capillary
Data collection mode Transmission
Scan method Step
2θ values (°) 2θmin = 0.510, 2θmax = 49.995, 2θstep = 0.001
 
Refinement
R factors and goodness of fit Rp = 0.054, Rwp = 0.065, Rexp = 0.046, χ2 = 2.117
No. of parameters 89
No. of restraints 52
(Δ/σ)max 10.698
Computer programs: GSAS-II (Toby & Von Dreele, 2013View full citation).

The pattern was indexed on a primitive ortho­rhom­bic unit cell with a = 6.90090, b = 10.33125, c = 20.06161 Å, V = 1430.29 Å3, and Z = 4 using JADE Pro (MDI, 2025View full citation). The space group suggested by EXPO2014 (Altomare et al., 2013View full citation) was P212121, which was confirmed by the successful solution and refinement of the structure.

The mol­ecular structure of levosimendan was downloaded from PubChem (Kim et al., 2023View full citation) as Conformer3D_COMPOUND_CID_3033825.sdf. It was converted to a *.mol2 file using Mercury (Macrae et al., 2020View full citation). The structure was solved using Monte Carlo simulated annealing techniques as implemented in EXPO2014 (Altomare et al., 2013View full citation).

Rietveld refinement was carried out using GSAS-II (Toby & Von Dreele, 2013View full citation). Only the 2.0–25.0° portion of the pattern was included in the refinements (dmin = 1.079 Å). All non-H bond distances and angles were subjected to restraints, based on a Mercury/Mogul Geometry Check (Sykes et al., 2011View full citation; Bruno et al., 2004View full citation). The Mogul average and standard deviation for each qu­antity were used as the restraint parameters. The phenyl ring was restrained to be planar. The restraints contributed 4.4% to the overall χ2. The hydrogen atoms were included in calculated positions, which were recalculated during the refinement using Materials Studio (Dassault Systèmes, 2024). The Uiso of the non-H atoms were grouped by chemical similarity. The Uiso of the H atoms were fixed at 1.2× the Uiso of the heavy atom to which they are attached. The peak profiles were described using the generalized microstrain model (Stephens, 1999View full citation). The background was modeled using a six-term shifted Chebyshev polynomial, with peaks at 5.71 and 8.19° to model the scattering from the Kapton capillary and any amorphous component of the sample. The background is different from the usual one from the Kapton capillary, suggesting that the sample really does contain an amorphous component. A few unindexed peaks were present in the pattern. These were best matched by PDF entry 02-072-2436 for poly(ɛ-caprolactone) (CSD Refcode WIMXAR; Bittiger et al., 1970View full citation), which was included in the refinement as a second phase. Its concentration was refined to 0.3 wt%.

The final refinement of 89 variables using 23,001 observations and 52 restraints yielded the residuals Rwp = 0.06661 and GOF = 1.45. The largest peak (1.36 Å from C8) and hole (1.20 Å from C17) in the difference Fourier map were 0.13 (4) and −0.13 (4) e Å−3, respectively. The final Rietveld plot is shown in Fig. 9[link]. The largest features in the normalized error plot are in the shapes of some of the strong low-angle peaks.

[Figure 9]
Figure 9
The Rietveld plot for levosimendan. The blue crosses represent the observed data points, and the green line is the calculated pattern. The cyan curve is the normalized error plot, and the red line is the background curve. The blue tick marks indicate the peak positions for levosimendan. The vertical scale has been multiplied by a factor of 10× for 2θ > 10.0°.

The crystal structure of levosimendan was optimized (fixed experimental unit cell) with density functional theory techniques using VASP (Kresse & Furthmüller, 1996View full citation) through the MedeA graphical inter­face (Materials Design, 2024View full citation). The calculation was carried out on 32 cores of a 144-core (768 Gb memory) HPE Superdome Flex 280 Linux server 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 × 2× 1 mesh, and took ∼2.6 h. Single-point density functional theory calculations (fixed experimental cell) and population analysis were carried out using CRYSTAL23 (Erba et al., 2023View full citation); (fixed experimental cell) and population analysis were carried out using CRYSTAL17 (Dovesi et al., 2018View full citation). The basis sets for the H, C, N and O atoms in the calculation were those of Gatti et al. (1994View full citation). The calculations were run on a 3.5 GHz PC using 8 k-points and the B3LYP functional, and took ∼1.4 h.

Supporting information

CCDC references: 2554934; 2554935; 2554933

Crystal structure: contains datablocks levosimendan_publ, levosimendan_overall, levosimendan, poly_caprolactone, levosimendan_pwd_0, levosimendan_VASP. DOI: https://doi.org/10.1107/S2056989026005190/jw2008sup1.cif

Supporting information file. DOI: https://doi.org/10.1107/S2056989026005190/jw2008levosimendansup2.cml

checkCIF report


Computing details top

2-({4-[(4R)-4-methyl-6-oxo-4,5-dihydro-1H-pyridazin-3-yl]phenyl}hydrazinylidene)propanedinitrile (levosimendan) top
Crystal data top
C14H12N6OV = 1415.53 (2) Å3
Mr = 280.29Z = 4
Orthorhombic, P212121Dx = 1.315 Mg m−3
a = 6.88117 (5) ÅSynchrotron radiation
b = 10.29085 (14) ÅT = 295 K
c = 19.9896 (2) Åcylinder, 2 × 1.5 mm
Data collection top
11-BM, APS
diffractometer		Data collection mode: transmission
Specimen mounting: Kapton capillaryScan method: step
Refinement top
Weighting scheme based on measured s.u.'s Preferred orientation correction: Simple spherical harmonic correction Order = 2 Coefficients: 0:0:C(2,0) = -0.0780; 0:0:C(2,2) = -0.0670
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.3588 (6)0.3414 (4)1.22287 (18)0.0376 (10)*
N20.2838 (11)0.6044 (3)1.10975 (16)0.0376 (10)*
N30.2866 (9)0.5248 (3)1.16716 (16)0.0376 (10)*
N40.2546 (9)0.8551 (4)0.81892 (15)0.0470 (11)*
N50.3124 (9)0.9785 (4)0.8192 (2)0.0470 (11)*
N60.3644 (8)1.2937 (4)0.7777 (3)0.0470 (11)*
N70.2169 (10)0.9602 (6)0.6485 (2)0.0470 (11)*
C80.3240 (7)0.3997 (3)1.04589 (17)0.0376 (10)*
C90.4339 (7)0.3493 (4)1.10531 (19)0.0376 (10)*
C100.3069 (9)0.5467 (2)1.05283 (14)0.0376 (10)*
C110.1216 (10)0.3375 (5)1.0463 (3)0.0376 (10)*
C120.2985 (13)0.6283 (2)0.99214 (15)0.0394 (12)*
C130.3476 (10)0.4004 (3)1.16966 (14)0.0376 (10)*
C140.2772 (11)0.5712 (3)0.92960 (18)0.0394 (12)*
C150.2935 (14)0.7636 (3)0.99683 (16)0.0394 (12)*
C160.2604 (12)0.6463 (3)0.87291 (16)0.0394 (12)*
C170.2957 (13)0.8390 (3)0.93951 (18)0.0394 (12)*
C180.2734 (13)0.7806 (3)0.87704 (15)0.0394 (12)*
C190.2862 (11)1.0528 (4)0.7653 (2)0.0470 (11)*
C200.3161 (9)1.1878 (4)0.7732 (3)0.0470 (11)*
C210.2562 (7)1.0050 (6)0.6992 (2)0.0470 (11)*
H220.397400.372201.002100.0451*
H230.584700.381001.102900.0451*
H240.425500.246101.109600.0451*
H250.055300.326401.093000.0451*
H260.014000.397201.016700.0451*
H270.122400.246501.018000.0451*
H280.244900.582601.208200.0451*
H290.288300.466800.921500.0473*
H300.322400.813601.043600.0473*
H310.284900.601900.823800.0473*
H320.325200.946100.943200.0473*
H330.319800.816700.776600.0564*
Geometric parameters (Å, º) top
O1—C131.227 (3)C14—C121.389 (2)
N2—N31.410 (3)C14—C161.376 (2)
N2—C101.2931 (13)C14—H291.089 (3)
N3—N21.410 (3)C15—C121.396 (2)
N3—C131.348 (2)C15—C171.384 (2)
N3—H281.053 (2)C15—H301.086 (3)
N4—N51.331 (4)C16—C141.376 (2)
N4—C181.398 (2)C16—C181.388 (2)
N4—H331.036 (5)C16—H311.096 (3)
N5—N41.331 (4)C17—C151.384 (2)
N5—C191.333 (3)C17—C181.394 (2)
N6—C201.143 (3)C17—H321.123 (3)
N7—C211.146 (3)C18—N41.398 (2)
C8—C91.501 (4)C18—C161.388 (2)
C8—C101.5239 (19)C18—C171.394 (2)
C8—C111.533 (4)C19—N51.333 (3)
C8—H221.050 (4)C19—C201.414 (3)
C9—C81.501 (4)C19—C211.424 (3)
C9—C131.512 (2)C20—N61.143 (3)
C9—H231.089 (6)C20—C191.414 (3)
C9—H241.067 (5)C21—N71.146 (3)
C10—N21.2931 (13)C21—C191.424 (3)
C10—C81.5239 (19)H22—C81.050 (4)
C10—C121.4765 (18)H23—C91.089 (6)
C11—C81.533 (4)H24—C91.067 (5)
C11—H251.046 (7)H25—C111.046 (7)
C11—H261.129 (6)H26—C111.129 (6)
C11—H271.093 (6)H27—C111.093 (6)
C12—C101.4765 (18)H28—N31.053 (2)
C12—C141.389 (2)H29—C141.089 (3)
C12—C151.396 (2)H30—C151.086 (3)
C13—O11.227 (3)H31—C161.096 (3)
C13—N31.348 (2)H32—C171.123 (3)
C13—C91.512 (2)H33—N41.036 (5)
N3—N2—C10116.61 (13)H26—C11—H27101.5 (5)
N2—N3—C13125.87 (14)C10—C12—C14120.21 (13)
N2—N3—H28107.6 (3)C10—C12—C15120.85 (13)
C13—N3—H28126.3 (3)C14—C12—C15118.67 (14)
N5—N4—C18119.54 (17)O1—C13—N3121.45 (18)
N5—N4—H33103.7 (5)O1—C13—C9122.7 (2)
C18—N4—H33115.4 (5)N3—C13—C9114.94 (16)
N4—N5—C19120.3 (3)C12—C14—C16120.84 (13)
C9—C8—C10108.08 (16)C12—C14—H29122.9 (3)
C9—C8—C11108.0 (3)C16—C14—H29115.9 (3)
C10—C8—C11110.1 (2)C12—C15—C17120.23 (17)
C9—C8—H22108.9 (3)C12—C15—H30121.8 (3)
C10—C8—H22112.4 (3)C17—C15—H30116.4 (3)
C11—C8—H22109.2 (4)C14—C16—C18120.31 (14)
C8—C9—C13110.80 (17)C14—C16—H31119.4 (3)
C8—C9—H23110.0 (4)C18—C16—H31117.3 (3)
C13—C9—H23107.9 (4)C15—C17—C18119.91 (15)
C8—C9—H24112.4 (4)C15—C17—H32119.9 (3)
C13—C9—H24104.9 (3)C18—C17—H32120.1 (3)
H23—C9—H24110.7 (3)N4—C18—C16119.42 (19)
N2—C10—C8123.04 (13)N4—C18—C17121.19 (19)
N2—C10—C12117.21 (11)C16—C18—C17119.32 (13)
C8—C10—C12119.53 (14)N5—C19—C20117.0 (3)
C8—C11—H25116.5 (5)N5—C19—C21124.8 (4)
C8—C11—H26111.5 (4)C20—C19—C21117.6 (3)
H25—C11—H26103.9 (6)N6—C20—C19171.3 (8)
C8—C11—H27110.5 (5)N7—C21—C19173.4 (7)
H25—C11—H27111.8 (5)
(poly_caprolactone) top
Crystal data top
C7H12O3c = 17.297 Å
Mr = 144.17V = 644.92 Å3
Orthorhombic, P212121Z = 4
a = 7.496 ÅDx = 1.485 Mg m−3
b = 4.974 ÅT = 295 K
Refinement top
Weighting scheme based on measured s.u.'s 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
O10.204800.032800.050400.0300*
C10.29980−0.036500.118200.0300*
H10.31360−0.264000.118200.0300*
H20.420900.098900.118200.0300*
C20.200300.036500.191200.0300*
H30.196500.263800.191200.0300*
H40.07920−0.090000.191200.0300*
C30.29980−0.036500.264400.0300*
H50.31360−0.264000.264400.0300*
H60.420900.098900.264400.0300*
C40.200300.036500.337400.0300*
H70.196500.263900.337400.0300*
H80.07920−0.090000.337400.0300*
C50.29980−0.036500.410600.0300*
H90.31360−0.264000.410600.0300*
H100.420900.098900.410600.0300*
C60.200300.036500.483600.0300*
O20.052300.144800.483600.0300*
O1A0.29520−0.032800.550400.0300*
C1A0.200200.036500.618200.0300*
H1A0.186400.264000.618200.0300*
H2A0.07910−0.098900.618200.0300*
(levosimendan_VASP) top
Crystal data top
C14H12N6Ob = 10.29094 Å
Mr = 280.29c = 19.98971 Å
Orthorhombic, P212121V = 1415.54 Å3
a = 6.88115 ÅZ = 4
Data collection top
VASP calculationk = →
h = →l = →
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/Beq
O10.343510.338050.22507
N20.289000.601450.11095
N30.288100.523380.16675
N40.271680.85295−0.18238
N50.299330.97759−0.18229
N60.342151.29512−0.22840
N70.220550.96110−0.35824
C80.315760.398200.04687
C90.426980.343200.10668
C100.304190.544530.05297
C110.111160.339150.04198
C120.299470.62633−0.00706
C130.348620.397640.17079
C140.284200.56979−0.07082
C150.306340.76323−0.00282
C160.273340.64546−0.12807
C170.298460.83982−0.05964
C180.281140.78090−0.12276
C190.291821.04651−0.23869
C200.320281.18248−0.23230
C210.253130.99842−0.30401
H220.396450.373190.00131
H230.581980.370940.10442
H240.419020.236810.10891
H250.023250.363800.08617
H260.034360.37420−0.00270
H270.123250.232760.03974
H280.247120.571300.20980
H290.278700.46472−0.07700
H300.318180.808720.04627
H310.257510.60048−0.17707
H320.305440.94518−0.05562
H330.240290.80072−0.22589
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H33···O11.0451.8262.813156.1
N4—H33···C211.0452.5662.85895.2
N3—H28···N61.0311.9482.947162.3
C16—H31···O11.0892.1703.049136.0
C15—H30···N21.0902.5022.82195.3
C9—H24···N71.0972.3463.366153.9
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···AMulliken overlap
N4—H33···O11.0451.8262.813156.10.058
N4—H33···C211.0452.5662.85895.20.011
N3—H28···N61.0311.9482.947162.30.048
C16—H31···O11.0892.1703.049136.00.031
C15—H30···N21.0902.5022.82195.30.014
C9—H24···N71.0972.3463.366153.90.016
 

Acknowledgements

Use of the Advanced Photon Source at Argonne National Laboratory was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We thank Saul Lapidus for his assistance in the data collection. We also thank the ICDD team – Megan Rost, Steve Trimble, and Dave Bohnenberger – for their contribution to research, sample preparation, and in-house XRD data collection and verification.

Funding information

Funding for this research was provided by: International Centre for Diffraction Data (grant No. 09-03).

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ISSN: 2056-9890
Volume 82| Part 6| June 2026| Pages 707-711
https://doi.org/10.1107/S2056989026005190
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