Memanti­nium chloride 0.1-hydrate

Lou, W.-J.; Hu, X.-R.; Gu, J.-M.

doi:10.1107/S1600536809031791

organic compounds

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ISSN: 2056-9890

Volume 65| Part 9| September 2009| Page o2191

doi:10.1107/S1600536809031791

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Memantinium chloride 0.1-hydrate

Wei-Jian Lou,^a Xiu-Rong Hu ^b ^* and Jian-Ming Gu ^b

^aDepartment of Pharmacy, Sir Run Run Shaw Hospital of School of Medicine, Sir Run Run Shaw Institute of Clinical Medicine, Zhejiang University, Hangzhou 310016, People's Republic of China, and ^bCenter of Analysis and Measurement, Zhejiang University, Hangzhou 310028, People's Republic of China
^*Correspondence e-mail: huxiurong@yahoo.com.cn

(Received 7 August 2009; accepted 12 August 2009; online 19 August 2009)

The crystal structure of the title compound, C₁₂H₂₂N⁺·Cl⁻·0.1H₂O, consists of (3,5-dimethyl-1-adamantyl)ammonium chloride (memantinium chloride) and uncoordinated water molecules. The four six-membered rings of the memantinium cation assume typical chair conformations. The Cl⁻ counter-anion links with the memantinium cation via N—H⋯Cl hydrogen bonding, forming channels where the disordered crystal water molecules are located. The O atom of the water molecule is located on a threefold rotation axis, its two H atoms symmetrically distributed over six sites; the water molecule links with the Cl⁻ anions via O—H⋯Cl hydrogen bonding.

Related literature

For applications of memantine in medicine, see: Parsons et al. (1999 ); Tariot et al. (2004 ). For a related structure, see: Zahid et al. (2009 ). The H atoms of the ncoordinated water molecule were placed at calculated positions, see: Nardelli (1999 ).

Experimental

Crystal data

C₁₂H₂₂N⁺·Cl⁻·0.1H₂O
M_r = 217.56
Trigonal, R 3c
a = 28.3787 (11) Å
c = 8.5236 (4) Å
V = 5944.8 (4) Å³
Z = 18
Mo Kα radiation
μ = 0.26 mm⁻¹
T = 294 K
0.41 × 0.18 × 0.16 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ) T_min = 0.888, T_max = 0.959
18491 measured reflections
2845 independent reflections
1671 reflections with I > 2σ(I)
R_int = 0.043

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.104
S = 1.09
2845 reflections
132 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.31 e Å⁻³
Absolute structure: Flack (1983 ), 1329 Friedel pairs
Flack parameter: 0.06 (9)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯Cl1ⁱ	0.89	2.26	3.147 (3)	176
N1—H1B⋯Cl1ⁱⁱ	0.89	2.28	3.161 (2)	171
N1—H1C⋯Cl1	0.89	2.26	3.148 (3)	175
O1—H1E⋯Cl1ⁱⁱ	0.86	2.62	3.486 (17)	179
O1—H1F⋯Cl1	0.91	2.93	3.81 (2)	163
Symmetry codes: (i) -y+1, x-y+1, z; (ii) $[-x+y, y, z+{\script{1\over 2}}]$ .

Data collection: PROCESS-AUTO (Rigaku, 2006 ); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku, 2007 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809031791/xu2585sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809031791/xu2585Isup2.hkl

checkCIF report

Comment top

The title compound is one of a small group of tricycle antiviral drugs (TVA). Memantine also provides good and persistent activation of central nervous N-methyl-D-aspartate (NMDA) receptors, and, thus can be used in the treatment of Parkinson's disease and Alzheimer's disease (Parsons et al., 1999; Tariot et al., 2004).

In the asymmetric unit of the crystal structure of the title compound, there are one mamentinium cation, one Cl^- anion and 0.10 lattice water molecule. The expected proton transfer from hydrochloric acid to N1 atom of amino group occurs. The four six-membered rings of the memantinium cation assume typical chair conformations, which is comparable with that found in related structures (Zahid et al., 2009). The Cl^- counter-anion links with the memantinium cation via N—H···Cl hydrogen bonding (Fig. 1). The lattice water molecules are located on the channels formed by memantininum cations and Cl^- anions (Fig. 2). The O atom of lattice water molecule is located at the threefold rotation axis, and its two H atoms are symmetrically distributed over six sites and linked to Cl^- anions via O—H···Cl hydrogen bonding (Table 1).

Related literature top

For applications of memantine in medicine, see: Parsons et al. (1999); Tariot et al. (2004). For a related structure, see: Zahid et al. (2009). The H atoms of the ncoordinated water molecule were placed at calculated positions, see: Nardelli (1999).

Experimental top

The crude product is supplied by Zhejiang Apeloa Pharmaceutical Co.,LTD. It was recrystallized from ethanol solution, giving colorless crystals of (1) suitable for X-ray diffraction.

Computing details top

Data collection: PROCESS-AUTO (Rigaku, 2006); cell refinement: PROCESS-AUTO (Rigaku, 2006); data reduction: CrystalStructure (Rigaku, 2007); program(s) used to solve structure: SHELXL97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. Molecular structure of the title compound showing atom-labelling scheme and displacement ellipsoids at 30% probability level. H atoms are shown as small circles of arbitary radii. Dashed lines indicate the hydrogen bonding.
	Fig. 2. The unit cell packing diagram of the title compound.

(3,5-dimethyl-1-adamantyl)ammonium chloride 0.1-hydrate top

Crystal data top

C₁₂H₂₂N·Cl·0.1(H₂O)	D_x = 1.094 Mg m⁻³
M_r = 217.56	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 10816 reflections
Hall symbol: R 3 -2"c	θ = 3.2–27.4°
a = 28.3787 (11) Å	µ = 0.26 mm⁻¹
c = 8.5236 (4) Å	T = 294 K
V = 5944.8 (4) Å³	Block, colorless
Z = 18	0.41 × 0.18 × 0.16 mm
F(000) = 2142

Data collection top

Rigaku R-AXIS RAPID diffractometer	2845 independent reflections
Radiation source: rolling anode	1671 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.043
Detector resolution: 10.00 pixels mm^-1	θ_max = 27.4°, θ_min = 3.2°
ω scans	h = −36→36
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −36→36
T_min = 0.888, T_max = 0.959	l = −11→9
18491 measured reflections

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.034	w = 1/[σ²(F_o²) + (0.0331P)² + 3.5112P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.104	(Δ/σ)_max = 0.001
S = 1.09	Δρ_max = 0.28 e Å⁻³
2845 reflections	Δρ_min = −0.31 e Å⁻³
132 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.00185 (17)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1329 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.06 (9)

Crystal data top

C₁₂H₂₂N·Cl·0.1(H₂O)	Z = 18
M_r = 217.56	Mo Kα radiation
Trigonal, R3c	µ = 0.26 mm⁻¹
a = 28.3787 (11) Å	T = 294 K
c = 8.5236 (4) Å	0.41 × 0.18 × 0.16 mm
V = 5944.8 (4) Å³

Data collection top

Rigaku R-AXIS RAPID diffractometer	2845 independent reflections
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	1671 reflections with I > 2σ(I)
T_min = 0.888, T_max = 0.959	R_int = 0.043
18491 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	H-atom parameters constrained
wR(F²) = 0.104	Δρ_max = 0.28 e Å⁻³
S = 1.09	Δρ_min = −0.31 e Å⁻³
2845 reflections	Absolute structure: Flack (1983), 1329 Friedel pairs
132 parameters	Absolute structure parameter: 0.06 (9)
1 restraint

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
N1	0.33309 (10)	0.56273 (9)	0.6470 (3)	0.0597 (6)
H1A	0.3632	0.5911	0.6098	0.090*
H1B	0.3320	0.5656	0.7508	0.090*
H1C	0.3041	0.5620	0.6046	0.090*
C1	0.33298 (13)	0.51132 (11)	0.6066 (3)	0.0552 (7)
C7	0.28247 (16)	0.41097 (14)	0.6378 (5)	0.0840 (10)
H7	0.2498	0.3798	0.6813	0.101*
C5	0.38468 (14)	0.46190 (13)	0.6423 (4)	0.0727 (9)
C4	0.38361 (11)	0.51418 (10)	0.6791 (3)	0.0621 (7)
H4A	0.3833	0.5187	0.7918	0.074*
H4B	0.4160	0.5453	0.6370	0.074*
C12	0.43554 (15)	0.46469 (17)	0.7130 (5)	0.1084 (13)
H12A	0.4674	0.4950	0.6689	0.130*
H12B	0.4357	0.4317	0.6898	0.130*
H12C	0.4355	0.4691	0.8246	0.130*
C2	0.28213 (12)	0.46352 (12)	0.6771 (4)	0.0720 (8)
H2A	0.2498	0.4621	0.6339	0.086*
H2B	0.2819	0.4678	0.7899	0.086*
C10	0.38348 (15)	0.45520 (14)	0.4635 (4)	0.0764 (9)
H10A	0.4159	0.4856	0.4190	0.092*
H10B	0.3841	0.4222	0.4388	0.092*
C3	0.33333 (14)	0.50494 (13)	0.4295 (3)	0.0647 (9)
H3A	0.3653	0.5360	0.3853	0.078*
H3B	0.3014	0.5037	0.3844	0.078*
C6	0.33304 (14)	0.41367 (13)	0.7103 (5)	0.0874 (10)
H6A	0.3331	0.3801	0.6888	0.105*
H6B	0.3324	0.4177	0.8232	0.105*
C9	0.33374 (13)	0.45250 (12)	0.3886 (4)	0.0732 (8)
C11	0.33487 (18)	0.44638 (16)	0.2099 (4)	0.1064 (14)
H11A	0.3670	0.4769	0.1678	0.128*
H11B	0.3032	0.4450	0.1644	0.128*
H11C	0.3351	0.4134	0.1858	0.128*
C8	0.28330 (16)	0.40466 (14)	0.4610 (5)	0.0876 (11)
H8A	0.2509	0.4025	0.4157	0.105*
H8B	0.2829	0.3711	0.4369	0.105*
Cl1	0.22918 (3)	0.56280 (3)	0.51793 (11)	0.0756 (2)
O1	0.3333	0.6667	0.800 (4)	0.181 (9)	0.30
H1E	0.3330	0.6410	0.8557	0.272*	0.10
H1F	0.3070	0.6480	0.7275	0.272*	0.10

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0637 (13)	0.0571 (13)	0.0653 (14)	0.0355 (12)	−0.0009 (11)	0.0000 (11)
C1	0.0562 (17)	0.0471 (16)	0.065 (2)	0.0274 (14)	0.0031 (14)	0.0011 (13)
C7	0.077 (2)	0.0513 (19)	0.112 (3)	0.0234 (17)	0.011 (2)	0.0112 (17)
C5	0.074 (2)	0.0604 (19)	0.094 (3)	0.0408 (18)	−0.0034 (17)	0.0013 (17)
C4	0.0613 (16)	0.0568 (16)	0.0704 (18)	0.0312 (13)	−0.0010 (14)	0.0009 (14)
C12	0.110 (3)	0.110 (3)	0.137 (4)	0.079 (3)	−0.029 (3)	−0.011 (2)
C2	0.0639 (18)	0.0590 (17)	0.088 (2)	0.0269 (15)	0.0116 (15)	0.0076 (15)
C10	0.083 (2)	0.066 (2)	0.091 (2)	0.0453 (18)	0.0076 (18)	−0.0068 (18)
C3	0.074 (2)	0.0591 (18)	0.066 (2)	0.0364 (17)	−0.0033 (17)	−0.0064 (14)
C6	0.102 (3)	0.064 (2)	0.101 (3)	0.0448 (19)	0.009 (2)	0.0171 (18)
C9	0.088 (2)	0.0599 (17)	0.077 (2)	0.0406 (17)	−0.0032 (17)	−0.0150 (15)
C11	0.150 (4)	0.094 (3)	0.085 (3)	0.069 (3)	−0.009 (2)	−0.028 (2)
C8	0.086 (3)	0.0538 (19)	0.115 (3)	0.0293 (19)	−0.011 (2)	−0.016 (2)
Cl1	0.0867 (6)	0.0914 (6)	0.0679 (4)	0.0589 (4)	−0.0076 (5)	−0.0064 (5)
O1	0.145 (9)	0.145 (9)	0.25 (3)	0.073 (4)	0.000	0.000

Geometric parameters (Å, º) top

N1—C1	1.497 (3)	C2—H2A	0.9700
N1—H1A	0.8900	C2—H2B	0.9700
N1—H1B	0.8900	C10—C9	1.516 (5)
N1—H1C	0.8900	C10—H10A	0.9700
C1—C3	1.521 (3)	C10—H10B	0.9700
C1—C2	1.525 (4)	C3—C9	1.534 (4)
C1—C4	1.529 (4)	C3—H3A	0.9700
C7—C8	1.519 (5)	C3—H3B	0.9700
C7—C6	1.529 (5)	C6—H6A	0.9700
C7—C2	1.533 (5)	C6—H6B	0.9700
C7—H7	0.9800	C9—C8	1.526 (5)
C5—C12	1.529 (4)	C9—C11	1.535 (5)
C5—C4	1.532 (4)	C11—H11A	0.9600
C5—C10	1.534 (4)	C11—H11B	0.9600
C5—C6	1.533 (5)	C11—H11C	0.9600
C4—H4A	0.9700	C8—H8A	0.9700
C4—H4B	0.9700	C8—H8B	0.9700
C12—H12A	0.9600	O1—H1E	0.8634
C12—H12B	0.9600	O1—H1F	0.9108
C12—H12C	0.9600

C1—N1—H1A	109.5	C7—C2—H2B	110.0
C1—N1—H1B	109.5	H2A—C2—H2B	108.4
H1A—N1—H1B	109.5	C9—C10—C5	112.8 (3)
C1—N1—H1C	109.5	C9—C10—H10A	109.0
H1A—N1—H1C	109.5	C5—C10—H10A	109.0
H1B—N1—H1C	109.5	C9—C10—H10B	109.0
N1—C1—C3	110.3 (3)	C5—C10—H10B	109.0
N1—C1—C2	108.4 (2)	H10A—C10—H10B	107.8
C3—C1—C2	110.2 (2)	C1—C3—C9	110.2 (3)
N1—C1—C4	108.1 (2)	C1—C3—H3A	109.6
C3—C1—C4	110.2 (2)	C9—C3—H3A	109.6
C2—C1—C4	109.5 (2)	C1—C3—H3B	109.6
C8—C7—C6	109.7 (3)	C9—C3—H3B	109.6
C8—C7—C2	109.8 (3)	H3A—C3—H3B	108.1
C6—C7—C2	109.0 (3)	C7—C6—C5	110.2 (3)
C8—C7—H7	109.4	C7—C6—H6A	109.6
C6—C7—H7	109.4	C5—C6—H6A	109.6
C2—C7—H7	109.4	C7—C6—H6B	109.6
C12—C5—C4	110.2 (3)	C5—C6—H6B	109.6
C12—C5—C10	111.1 (3)	H6A—C6—H6B	108.1
C4—C5—C10	108.2 (2)	C10—C9—C8	108.1 (3)
C12—C5—C6	110.7 (3)	C10—C9—C3	108.3 (3)
C4—C5—C6	108.3 (3)	C8—C9—C3	108.2 (3)
C10—C5—C6	108.2 (3)	C10—C9—C11	110.6 (3)
C1—C4—C5	109.8 (2)	C8—C9—C11	111.3 (3)
C1—C4—H4A	109.7	C3—C9—C11	110.2 (3)
C5—C4—H4A	109.7	C9—C11—H11A	109.5
C1—C4—H4B	109.7	C9—C11—H11B	109.5
C5—C4—H4B	109.7	H11A—C11—H11B	109.5
H4A—C4—H4B	108.2	C9—C11—H11C	109.5
C5—C12—H12A	109.5	H11A—C11—H11C	109.5
C5—C12—H12B	109.5	H11B—C11—H11C	109.5
H12A—C12—H12B	109.5	C7—C8—C9	111.0 (3)
C5—C12—H12C	109.5	C7—C8—H8A	109.4
H12A—C12—H12C	109.5	C9—C8—H8A	109.4
H12B—C12—H12C	109.5	C7—C8—H8B	109.4
C1—C2—C7	108.4 (3)	C9—C8—H8B	109.4
C1—C2—H2A	110.0	H8A—C8—H8B	108.0
C7—C2—H2A	110.0	H1E—O1—H1F	102.8
C1—C2—H2B	110.0

N1—C1—C4—C5	179.2 (2)	C8—C7—C6—C5	59.3 (4)
C3—C1—C4—C5	−60.1 (3)	C2—C7—C6—C5	−61.0 (4)
C2—C1—C4—C5	61.2 (3)	C12—C5—C6—C7	−179.5 (3)
C12—C5—C4—C1	179.4 (3)	C4—C5—C6—C7	59.6 (4)
C10—C5—C4—C1	57.8 (3)	C10—C5—C6—C7	−57.5 (4)
C6—C5—C4—C1	−59.4 (3)	C5—C10—C9—C8	−58.5 (3)
N1—C1—C2—C7	−179.1 (3)	C5—C10—C9—C3	58.5 (3)
C3—C1—C2—C7	60.0 (3)	C5—C10—C9—C11	179.4 (3)
C4—C1—C2—C7	−61.4 (3)	C1—C3—C9—C10	−58.1 (3)
C8—C7—C2—C1	−59.2 (4)	C1—C3—C9—C8	58.8 (3)
C6—C7—C2—C1	61.0 (4)	C1—C3—C9—C11	−179.2 (3)
C12—C5—C10—C9	−179.7 (3)	C6—C7—C8—C9	−59.8 (4)
C4—C5—C10—C9	−58.7 (3)	C2—C7—C8—C9	60.0 (4)
C6—C5—C10—C9	58.5 (3)	C10—C9—C8—C7	58.3 (4)
N1—C1—C3—C9	179.5 (3)	C3—C9—C8—C7	−58.8 (4)
C2—C1—C3—C9	−60.8 (3)	C11—C9—C8—C7	180.0 (3)
C4—C1—C3—C9	60.1 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1ⁱ	0.89	2.26	3.147 (3)	176
N1—H1B···Cl1ⁱⁱ	0.89	2.28	3.161 (2)	171
N1—H1C···Cl1	0.89	2.26	3.148 (3)	175
O1—H1E···Cl1ⁱⁱ	0.86	2.62	3.486 (17)	179
O1—H1F···Cl1	0.91	2.93	3.81 (2)	163

Symmetry codes: (i) −y+1, x−y+1, z; (ii) −x+y, y, z+1/2.

Experimental details

Crystal data
Chemical formula	C₁₂H₂₂N·Cl·0.1(H₂O)
M_r	217.56
Crystal system, space group	Trigonal, R3c
Temperature (K)	294
a, c (Å)	28.3787 (11), 8.5236 (4)
V (Å³)	5944.8 (4)
Z	18
Radiation type	Mo Kα
µ (mm⁻¹)	0.26
Crystal size (mm)	0.41 × 0.18 × 0.16

Data collection
Diffractometer	Rigaku R-AXIS RAPID diffractometer
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995)
T_min, T_max	0.888, 0.959
No. of measured, independent and observed [I > 2σ(I)] reflections	18491, 2845, 1671
R_int	0.043
(sin θ/λ)_max (Å⁻¹)	0.648

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.104, 1.09
No. of reflections	2845
No. of parameters	132
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.31
Absolute structure	Flack (1983), 1329 Friedel pairs
Absolute structure parameter	0.06 (9)

Computer programs: PROCESS-AUTO (Rigaku, 2006), CrystalStructure (Rigaku, 2007), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1ⁱ	0.89	2.26	3.147 (3)	176
N1—H1B···Cl1ⁱⁱ	0.89	2.28	3.161 (2)	171
N1—H1C···Cl1	0.89	2.26	3.148 (3)	175
O1—H1E···Cl1ⁱⁱ	0.86	2.62	3.486 (17)	179
O1—H1F···Cl1	0.91	2.93	3.81 (2)	163

Symmetry codes: (i) −y+1, x−y+1, z; (ii) −x+y, y, z+1/2.

Acknowledgements

The project was supported by the Zhejiang Provincial Natural Science Foundation of China.

References

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Higashi, T. (1995). ABSCOR. Rigaku Corporation, Tokyo, Japan. Google Scholar
Nardelli, M. (1999). J. Appl. Cryst. 32, 563–571. Web of Science CrossRef CAS IUCr Journals Google Scholar
Parsons, C. G., Danysz, W. & Quack, G. (1999). Neuropharmacology, 38, 735–767. Web of Science CrossRef PubMed CAS Google Scholar
Rigaku (2006). PROCESS-AUTO. Rigaku Corporation, Tokyo, Japan. Google Scholar
Rigaku (2007). CrystalStructure. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tariot, P. N., Farlow, M. R., Grossbeq, G. T., Graham, S. M., McDonald, S. & Gergel, I. (2004). J. Am. Med. Assoc. 291, 317–324. Web of Science CrossRef CAS Google Scholar
Zahid, M., Khawar Rauf, M., Bolte, M. & Hameed, S. (2009). Acta Cryst. E65, o1891. Web of Science CSD CrossRef IUCr Journals Google Scholar