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The crystal structure of the metastable form C polymorph of nifedipine [C17H18N2O6, 3,5-dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate] was determined by means of direct-space techniques applied to high-resolution synchrotron powder diffraction data. The polymorph crystallizes in the space group P\bar 1 and exhibits a molecular packing significantly different from that of the stable modification, with molecules aligned in an orthogonal configuration inside the unit cell. The molecular conformation, on the other hand, remains substantially unmodified between the two polymorphs. Additionally, in situ thermal characterization of nifedipine crystallization behaviour was performed, confirming the nucleation of another metastable polymorph (form B) prior to the complete crystallization of the stable modification. A complete structural characterization of form B was not possible owing to its very limited stability interval.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768111021653/kd5048sup1.cif
Contains datablock I

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768111021653/kd5048Isup2.rtv
Contains datablock I

CCDC reference: 842187

Computing details top

4-(2-nitrophenyl)-2,6-dimethyl-3,5dicarbomethoxy-1,4-dihydropyridine top
Crystal data top
C17H18N2O6γ = 81.782 (1)°
Mr = 346.34V = 1685.5 (9) Å3
Triclinic, P1Z = 4
a = 9.864 (1) ÅSynchrotron radiation, λ = 0.50000 Å
b = 13.893 (9) ŵ = 0.05 mm1
c = 14.287 (3) ÅT = 298 K
α = 61.227 (3)°yellow
β = 79.827 (2)°cylinder, 14 × 0.7 mm
Data collection top
Two-theta/omega SNB Diffractometer - ESRFScan method: step
Specimen mounting: capillary2θmin = 1.5°, 2θmax = 12.0°, 2θstep = 0.002°
Data collection mode: transmission
Refinement top
Rp = 0.15115 parameters
Rwp = 0.1720 restraints
Rexp = 0.0170 constraints
RBragg = 0.151H-atom parameters not refined
12508 data pointsBackground function: fourth-order polynomial
Profile function: Pseudo Voigt
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzBiso*/Beq
N1a0.8931 (3)1.1105 (2)0.2731 (4)1.51*
C1a1.0089 (4)1.0494 (2)0.2567 (2)1.51*
C2a1.0841 (3)1.1058 (2)0.1456 (3)1.51*
C3a1.0381 (3)0.9478 (3)0.3391 (3)1.51*
C4a1.1650 (3)0.8799 (4)0.3387 (3)1.51*
O1a1.2597 (5)0.9113 (5)0.2670 (2)1.51*
O2a1.1645 (2)0.7767 (3)0.4185 (2)1.51*
C5a1.2509 (2)0.6963 (4)0.3938 (3)1.51*
C6a0.9355 (4)0.8930 (2)0.4397 (4)1.51*
C7a0.8315 (4)0.9783 (3)0.4548 (2)1.51*
C8a0.7427 (3)0.9444 (3)0.5567 (4)1.51*
O3a0.7321 (2)0.8532 (4)0.6329 (2)1.51*
O4a0.6681 (3)1.0326 (3)0.5604 (5)1.51*
C9a0.5406 (4)1.0101 (3)0.6337 (2)1.51*
C10a0.8131 (2)1.0806 (5)0.3713 (4)1.51*
C11a0.7141 (4)1.1711 (2)0.3751 (3)1.51*
C12a0.8600 (2)0.8076 (3)0.4326 (2)1.51*
C13a0.7752 (3)0.8459 (3)0.3496 (2)1.51*
C14a0.7053 (3)0.7777 (5)0.3335 (3)1.51*
C15a0.7193 (3)0.6634 (2)0.3975 (2)1.51*
C16a0.8036 (4)0.6216 (5)0.4777 (3)1.51*
C17a0.8722 (4)0.6922 (2)0.4942 (4)1.51*
N2a0.9558 (4)0.6376 (3)0.5845 (3)1.51*
O5a1.0251 (5)0.5538 (3)0.6000 (2)1.51*
O6a0.9512 (3)0.6832 (5)0.6403 (3)1.51*
N1b0.6575 (3)0.6033 (3)0.7749 (2)1.51*
C1b0.7201 (2)0.5724 (4)0.8655 (4)1.51*
C2b0.7983 (3)0.6618 (3)0.8564 (4)1.51*
C3b0.7069 (3)0.4676 (3)0.9480 (3)1.51*
C4b0.7521 (4)0.4275 (4)1.0534 (3)1.51*
O1b0.7428 (2)0.3334 (2)1.1231 (2)1.51*
O2b0.7933 (4)0.5042 (2)1.0712 (3)1.51*
C5b0.9022 (2)0.4678 (4)1.1397 (5)1.51*
C6b0.6475 (5)0.3798 (2)0.9353 (3)1.51*
C7b0.5585 (5)0.4318 (4)0.8433 (3)1.51*
C8b0.4720 (3)0.3620 (3)0.8325 (4)1.51*
O3b0.4358 (3)0.3715 (3)0.7516 (3)1.51*
O4b0.4345 (2)0.2754 (3)0.9301 (5)1.51*
C9b0.4670 (3)0.1666 (3)0.9388 (3)1.51*
C10b0.5699 (3)0.5388 (5)0.7672 (3)1.51*
C11b0.4901 (2)0.5992 (4)0.6727 (3)1.51*
C12b0.7644 (3)0.3048 (2)0.9147 (5)1.51*
C13b0.8685 (4)0.3548 (4)0.8268 (3)1.51*
C14b0.9795 (3)0.2971 (4)0.8018 (5)1.51*
C15b0.9986 (2)0.1833 (2)0.8664 (3)1.51*
C16b0.9023 (5)0.1309 (2)0.9547 (2)1.51*
C17b0.7886 (4)0.1905 (3)0.9780 (3)1.51*
N2b0.6910 (3)0.1245 (3)1.0726 (3)1.51*
O5b0.6974 (3)0.0253 (3)1.1127 (2)1.51*
O6b0.6062 (3)0.1764 (3)1.1075 (5)1.51*
H1a1.033241.185030.101390.00*
H2a1.087811.057210.105580.00*
H3a1.187421.116030.150720.00*
H4a1.242870.616740.462480.00*
H5a1.355280.718250.371220.00*
H6a1.215770.694760.327760.00*
H7a0.991050.852350.507780.00*
H8a0.872461.172290.209870.00*
H9a0.490201.085580.629620.00*
H10a0.560400.954180.714200.00*
H11a0.472790.973070.610790.00*
H12a0.721391.242360.297750.00*
H13a0.734821.190270.434960.00*
H14a0.610681.144890.395770.00*
H15a0.765140.929470.298550.00*
H16a0.641310.810910.273690.00*
H17a0.667350.611950.384980.00*
H18a0.815310.537660.525730.00*
H1b0.675520.675360.712350.00*
H2b0.785850.733830.781150.00*
H3b0.903870.635340.862920.00*
H4b0.756360.681030.920610.00*
H5b0.925570.535291.148600.00*
H6b0.990220.436481.105870.00*
H7b0.865570.403451.217080.00*
H8b0.582220.332311.008250.00*
H9b0.431350.106181.018630.00*
H10b0.574490.153710.919970.00*
H11b0.413940.159730.882790.00*
H12b0.519430.682140.626480.00*
H13b0.380690.598870.699390.00*
H14b0.511030.559210.623340.00*
H15b0.858560.439260.779540.00*
H16b1.048740.337410.735120.00*
H17b1.081890.139270.848510.00*
H18b0.913800.047141.003420.00*
Geometric parameters (Å, º) top
N1a—C1a1.378 (5)N1b—C1b1.383 (5)
N1a—C10a1.380 (7)N1b—C10b1.383 (7)
N1a—H8a0.9294N1b—H1b0.9833
C1a—C2a1.496 (5)C1b—C2b1.496 (7)
C1a—C3a1.366 (5)C1b—C3b1.369 (7)
C2a—H1a1.0712C2b—H2b1.0724
C2a—H2a1.0684C2b—H3b1.0583
C2a—H3a1.0693C2b—H4b1.0746
C3a—C4a1.457 (6)C3b—C4b1.461 (5)
C3a—C6a1.524 (6)C3b—C6b1.523 (6)
C4a—O1a1.209 (5)C4b—O1b1.207 (6)
C4a—O2a1.335 (6)C4b—O2b1.337 (7)
O2a—C5a1.449 (7)O2b—C5b1.452 (6)
C5a—H4a1.0704C5b—H5b1.0667
C5a—H5a1.0652C5b—H6b1.0605
C5a—H6a1.0715C5b—H7b1.0735
C6a—C7a1.524 (6)C6b—C7b1.527 (6)
C6a—C12a1.539 (5)C6b—C12b1.528 (6)
C6a—H7a1.0665C6b—H8b1.0764
C7a—C8a1.455 (6)C7b—C8b1.456 (7)
C7a—C10a1.359 (7)C7b—C10b1.361 (8)
C8a—O3a1.213 (6)C8b—O3b1.211 (6)
C8a—O4a1.355 (7)C8b—O4b1.363 (8)
O4a—C9a1.452 (6)O4b—C9b1.448 (7)
C9a—H9a1.0744C9b—H9b1.0723
C9a—H10a1.0683C9b—H10b1.0583
C9a—H11a1.0765C9b—H11b1.0775
C10a—C11a1.495 (7)C10b—C11b1.498 (5)
C11a—H12a1.0703C11b—H12b1.0695
C11a—H13a1.0685C11b—H13b1.0792
C11a—H14a1.0764C11b—H14b1.0686
C12a—C13a1.416 (4)C12b—C13b1.422 (7)
C12a—C17a1.408 (6)C12b—C17b1.408 (7)
C13a—C14a1.371 (7)C13b—C14b1.362 (7)
C13a—H15a1.0333C13b—H15b1.0345
C14a—C15a1.400 (7)C14b—C15b1.400 (7)
C14a—H16a1.0344C14b—H16b1.0264
C15a—C16a1.378 (5)C15b—C16b1.384 (5)
C15a—H17a1.0323C15b—H17b1.0233
C16a—C17a1.394 (7)C16b—C17b1.387 (6)
C16a—H18a1.0316C16b—H18b1.0302
C17a—N2a1.475 (6)C17b—N2b1.481 (5)
N2a—O5a1.204 (6)N2b—O5b1.208 (6)
N2a—O6a1.226 (8)N2b—O6b1.223 (6)
C1a—N1a—C10a123.9 (4)C1b—N1b—C10b123.8 (4)
C1a—N1a—H8a112C1b—N1b—H1b118
C10a—N1a—H8a124C10b—N1b—H1b118
N1a—C1a—C2a112.9 (3)N1b—C1b—C2b112.7 (4)
N1a—C1a—C3a118.2 (3)N1b—C1b—C3b118.3 (4)
C2a—C1a—C3a128.9 (3)C2b—C1b—C3b128.9 (4)
C1a—C2a—H1a109C1b—C2b—H2b109
C1a—C2a—H2a110C1b—C2b—H3b110
C1a—C2a—H3a109C1b—C2b—H4b109
H1a—C2a—H2a110H2b—C2b—H3b111
H1a—C2a—H3a109H2b—C2b—H4b109
H2a—C2a—H3a109H3b—C2b—H4b109
C1a—C3a—C4a124.4 (3)C1b—C3b—C4b124.5 (4)
C1a—C3a—C6a122.0 (3)C1b—C3b—C6b121.9 (4)
C4a—C3a—C6a113.6 (3)C4b—C3b—C6b113.6 (3)
C3a—C4a—O1a122.7 (4)C3b—C4b—O1b122.6 (4)
C3a—C4a—O2a115.0 (4)C3b—C4b—O2b115.4 (4)
O1a—C4a—O2a122.0 (4)O1b—C4b—O2b121.7 (4)
C4a—O2a—C5a115.2 (3)C4b—O2b—C5b115.6 (4)
O2a—C5a—H4a109O2b—C5b—H5b109
O2a—C5a—H5a110O2b—C5b—H6b110
O2a—C5a—H6a109O2b—C5b—H7b108
H4a—C5a—H5a111H5b—C5b—H6b111
H4a—C5a—H6a109H5b—C5b—H7b109
H5a—C5a—H6a109H6b—C5b—H7b109
C3a—C6a—C7a110.9 (3)C3b—C6b—C7b111.1 (3)
C3a—C6a—C12a110.2 (3)C3b—C6b—C12b109.9 (3)
C3a—C6a—H7a108C3b—C6b—H8b108
C7a—C6a—C12a110.1 (3)C7b—C6b—C12b109.9 (3)
C7a—C6a—H7a108C7b—C6b—H8b108
C12a—C6a—H7a109C12b—C6b—H8b110
C6a—C7a—C8a118.5 (3)C6b—C7b—C8b118.7 (4)
C6a—C7a—C10a120.5 (4)C6b—C7b—C10b120.4 (4)
C8a—C7a—C10a120.7 (4)C8b—C7b—C10b120.6 (4)
C7a—C8a—O3a128.9 (4)C7b—C8b—O3b128.7 (4)
C7a—C8a—O4a110.5 (4)C7b—C8b—O4b110.8 (4)
O3a—C8a—O4a120.6 (4)O3b—C8b—O4b120.5 (4)
C8a—O4a—C9a116.3 (4)C8b—O4b—C9b116.5 (4)
O4a—C9a—H9a110O4b—C9b—H9b109
O4a—C9a—H10a111O4b—C9b—H10b110
O4a—C9a—H11a109O4b—C9b—H11b109
H9a—C9a—H10a110H9b—C9b—H10b111
H9a—C9a—H11a109H9b—C9b—H11b108
H10a—C9a—H11a108H10b—C9b—H11b109
N1a—C10a—C7a120.5 (4)N1b—C10b—C7b120.4 (4)
N1a—C10a—C11a113.7 (4)N1b—C10b—C11b113.7 (4)
C7a—C10a—C11a125.8 (4)C7b—C10b—C11b125.8 (4)
C10a—C11a—H12a110C10b—C11b—H12b110
C10a—C11a—H13a111C10b—C11b—H13b110
C10a—C11a—H14a109C10b—C11b—H14b110
H12a—C11a—H13a110H12b—C11b—H13b110
H12a—C11a—H14a109H12b—C11b—H14b109
H13a—C11a—H14a108H13b—C11b—H14b108
C6a—C12a—C13a117.9 (3)C6b—C12b—C13b117.8 (4)
C6a—C12a—C17a127.9 (3)C6b—C12b—C17b127.5 (4)
C13a—C12a—C17a114.0 (3)C13b—C12b—C17b114.5 (4)
C12a—C13a—C14a123.3 (3)C12b—C13b—C14b123.3 (4)
C12a—C13a—H15a119C12b—C13b—H15b118
C14a—C13a—H15a118C14b—C13b—H15b119
C13a—C14a—C15a120.7 (4)C13b—C14b—C15b120.1 (4)
C13a—C14a—H16a120C13b—C14b—H16b120
C15a—C14a—H16a120C15b—C14b—H16b120
C14a—C15a—C16a118.3 (4)C14b—C15b—C16b118.9 (3)
C14a—C15a—H17a121C14b—C15b—H17b121
C16a—C15a—H17a121C16b—C15b—H17b120
C15a—C16a—C17a120.3 (4)C15b—C16b—C17b120.3 (3)
C15a—C16a—H18a120C15b—C16b—H18b120
C17a—C16a—H18a120C17b—C16b—H18b119
C12a—C17a—C16a123.3 (4)C12b—C17b—C16b122.8 (4)
C12a—C17a—N2a121.6 (4)C12b—C17b—N2b122.1 (4)
C16a—C17a—N2a115.1 (4)C16b—C17b—N2b115.1 (3)
C17a—N2a—O5a120.7 (4)C17b—N2b—O5b121.2 (4)
C17a—N2a—O6a116.2 (4)C17b—N2b—O6b116.0 (4)
O5a—N2a—O6a123.1 (4)O5b—N2b—O6b122.8 (4)
 

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