[1-(Carboxy­meth­yl)cyclo­hexyl]­methan­aminium dihydrogen phosphate

Razzaq, S.N.; Khan, I.U.; Şahin, O.; Büyükgüngör, O.

doi:10.1107/S1600536810012973

organic compounds

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ISSN: 2056-9890

Volume 66| Part 5| May 2010| Page o1074

https://doi.org/10.1107/S1600536810012973

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[1-(Carboxymethyl)cyclohexyl]methanaminium dihydrogen phosphate

Syed Naeem Razzaq,^a Islam Ullah Khan,^a ^* Onur Şahin ^b and Orhan Büyükgüngör ^b

^aMaterials Chemistry Laboratry, Department of Chemistry, GC University, Lahore 54000, Pakistan, and ^bDepartment of Physics, Ondokuz Mayıs University, TR-55139 Samsun, Turkey
^*Correspondence e-mail: onurs@omu.edu.tr

(Received 5 April 2010; accepted 7 April 2010; online 14 April 2010)

In the title salt, C₉H₁₈NO₂⁺·H₂PO₄⁻, the cyclohexane ring is puckered, the total puckering amplitude Q_T being 0.555 (4) Å, and an intramolecular N—H⋯O hydrogen bond generates an S(7) ring. In the crystal structure, intermolecular N—H⋯O and O—H⋯O hydrogen bonds lead to R₂²(14), R₃³(8) and R₄²(8) rings, generating a two-dimensional layer.

Related literature

For related structures and medicinal background, see: Reece & Levendis (2008 ); Ibers (2001 ). For the graph-set analysis of hydrogen-bond patterns, see: Bernstein et al. (1995 ). For details of ring-puckering analysis, see: Cremer & Pople (1975 ). For bond-valence analysis and the positioning of H atoms, see: Brese & O'Keeffe (1991 ).

Experimental

Crystal data

C₉H₁₈NO₂⁺·H₂O₄P⁻
M_r = 269.23
Orthorhombic, P b c a
a = 10.473 (5) Å
b = 9.269 (3) Å
c = 26.468 (5) Å
V = 2569.4 (16) Å³
Z = 8
Mo Kα radiation
μ = 0.23 mm⁻¹
T = 296 K
0.31 × 0.25 × 0.22 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
14659 measured reflections
3185 independent reflections
1853 reflections with I > 2σ(I)
R_int = 0.071

Refinement

R[F² > 2σ(F²)] = 0.051
wR(F²) = 0.155
S = 1.06
3185 reflections
178 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O6—H6⋯O3ⁱ	0.83 (4)	1.77 (2)	2.602 (3)	173 (4)
O1—H1⋯O3ⁱⁱ	0.82 (2)	1.76 (2)	2.569 (3)	173 (5)
N1—H5⋯O1ⁱⁱⁱ	0.88 (2)	2.26 (3)	2.929 (4)	133 (3)
N1—H5⋯O2^iv	0.88 (2)	2.44 (3)	2.959 (3)	118 (3)
N1—H5⋯O5^iv	0.88 (2)	2.47 (3)	3.065 (3)	125 (3)
N1—H4⋯O5	0.91 (2)	1.89 (2)	2.760 (4)	158 (3)
N1—H3⋯O4	0.90 (2)	1.86 (2)	2.752 (3)	174 (3)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z]$ ; (ii) -x+2, -y, -z+1; (iii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (iv) -x+1, -y, -z+1.

Data collection: APEX2 (Bruker, 2009 ); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; 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: https://doi.org/10.1107/S1600536810012973/hb5398sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810012973/hb5398Isup2.hkl

checkCIF report

Comment top

The title compound is a salt of gabapentin (Ibers, 2001; Reece & Levendis, 2008) an antiepileptic drug has potential application in treatment of neuropathic pain. Herein we report the synthesis and crystal structure of title compound (I).

The molecular structure and atom-labelling scheme are shown in Fig. 1. Selected bond distances and angles are given in Table 1. The C9—O6 bond length [1.310 (4) Å] indicate significant single-bond character, whereas the C9—O5 bond length [1.213 (3) Å] is indicative of significant double-bond character. The cyclohexane ring exhibits a puckered conformation, with puckering parameters (Cremer & Pople, 1975) q₂ = 0.0246 (42) Å, q₃ = 0.5544 (42) Å, Q_T = 0.5547 (42) Å, φ = 318 (10)° and θ = 1.81 (43)°. The O—P—O angles lie in the range 106.35 (14)–115.00 (12)°. Linkages P1—O1 and P1—O2 constitute POH groups, as confirmed both by the location of H atoms in the difference Fourier maps and by bond-valence calculations (Brese & O'Keeffe, 1991).

The atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor (Table 2) to atom O5^iv so forming a centrosymmetric R₂²(14) ring (Bernstein et al., 1995) centred at (1/2, 0, 1/2). The combination of N—H···O and O—H···O hydrogen bonds generates R₃³(8) and R₄²(8) rings parallel to the [010] direction (Fig. 2).

Related literature top

For related structures and medicinal background, see: Reece & Levendis (2008); Ibers (2001). For the graph-set analysis of hydrogen-bond patterns, see: Bernstein et al. (1995). For details of ring-puckering analysis, see: Cremer & Pople (1975). For bond-valence analysis and the positioning of H atoms, see: Brese & O'Keeffe (1991).

Experimental top

To a 10 ml methanolic solution (0.002 M) of gabapentin was added 4 drops of phosphoric acid (85%). The mixture was heated and stirred for 30 min. Colourless prisms of (I) were obtained by slow evaporation from methanol.

Structure description top

For related structures and medicinal background, see: Reece & Levendis (2008); Ibers (2001). For the graph-set analysis of hydrogen-bond patterns, see: Bernstein et al. (1995). For details of ring-puckering analysis, see: Cremer & Pople (1975). For bond-valence analysis and the positioning of H atoms, see: Brese & O'Keeffe (1991).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); 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).

Figures top

	Fig. 1. A view of one molecule of (I), showing displacement ellipsoids drawn at the 30% probability level. Hydrogen bonds are indicated by dashed lines.
	Fig. 2. Part of the crystal structure of (I), showing the formation of a hydrogen-bonded sheet built from R₃³(8) and R₄²(8) rings. For the sake of clarity, H atoms not involved in the motif shown have been omitted.

[1-(Carboxymethyl)cyclohexyl]methanaminium dihydrogen phosphate top

Crystal data top

C₉H₁₈NO₂⁺·H₂O₄P⁻	F(000) = 1152
M_r = 269.23	D_x = 1.392 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 1923 reflections
a = 10.473 (5) Å	θ = 3.0–21.6°
b = 9.269 (3) Å	µ = 0.23 mm⁻¹
c = 26.468 (5) Å	T = 296 K
V = 2569.4 (16) Å³	Prism, colourless
Z = 8	0.31 × 0.25 × 0.22 mm

Data collection top

Bruker Kappa APEXII CCD diffractometer	1853 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.071
Graphite monochromator	θ_max = 28.3°, θ_min = 1.5°
φ and ω scans	h = −13→7
14659 measured reflections	k = −11→12
3185 independent reflections	l = −35→35

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.051	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.155	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ²(F_o²) + (0.0712P)²] where P = (F_o² + 2F_c²)/3
3185 reflections	(Δ/σ)_max < 0.001
178 parameters	Δρ_max = 0.34 e Å⁻³
6 restraints	Δρ_min = −0.45 e Å⁻³

Crystal data top

C₉H₁₈NO₂⁺·H₂O₄P⁻	V = 2569.4 (16) Å³
M_r = 269.23	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 10.473 (5) Å	µ = 0.23 mm⁻¹
b = 9.269 (3) Å	T = 296 K
c = 26.468 (5) Å	0.31 × 0.25 × 0.22 mm

Data collection top

Bruker Kappa APEXII CCD diffractometer	1853 reflections with I > 2σ(I)
14659 measured reflections	R_int = 0.071
3185 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.051	6 restraints
wR(F²) = 0.155	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	Δρ_max = 0.34 e Å⁻³
3185 reflections	Δρ_min = −0.45 e Å⁻³
178 parameters

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
C1	0.6575 (4)	0.1582 (5)	0.67421 (15)	0.0667 (12)
H1A	0.6569	0.2315	0.6481	0.080*
H1B	0.7457	0.1334	0.6812	0.080*
C2	0.5874 (3)	0.0253 (4)	0.65538 (12)	0.0413 (8)
H2A	0.5967	−0.0514	0.6801	0.050*
H2B	0.6266	−0.0070	0.6242	0.050*
C3	0.4441 (3)	0.0522 (3)	0.64599 (10)	0.0301 (7)
C4	0.3859 (4)	0.1206 (4)	0.69378 (12)	0.0477 (9)
H4A	0.2983	0.1474	0.6866	0.057*
H4B	0.3842	0.0485	0.7204	0.057*
C5	0.4563 (4)	0.2527 (4)	0.71319 (15)	0.0667 (12)
H5A	0.4489	0.3303	0.6888	0.080*
H5B	0.4178	0.2847	0.7446	0.080*
C6	0.5961 (5)	0.2189 (6)	0.72201 (16)	0.0874 (16)
H6A	0.6039	0.1492	0.7492	0.105*
H6B	0.6406	0.3061	0.7321	0.105*
C7	0.4205 (3)	0.1584 (3)	0.60270 (11)	0.0329 (7)
H7A	0.3293	0.1639	0.5966	0.040*
H7B	0.4487	0.2533	0.6133	0.040*
C8	0.3736 (3)	−0.0923 (3)	0.63691 (13)	0.0445 (9)
H8A	0.3624	−0.1395	0.6693	0.053*
H8B	0.2891	−0.0705	0.6239	0.053*
C9	0.4354 (3)	−0.1977 (3)	0.60166 (12)	0.0343 (7)
N1	0.4845 (2)	0.1225 (3)	0.55463 (9)	0.0296 (6)
H3	0.5685 (19)	0.141 (4)	0.5561 (14)	0.067 (12)*
H4	0.473 (4)	0.027 (2)	0.5469 (13)	0.069 (13)*
H5	0.454 (3)	0.173 (4)	0.5291 (11)	0.066 (12)*
O5	0.4571 (2)	−0.1736 (2)	0.55742 (8)	0.0417 (6)
O6	0.4610 (3)	−0.3214 (3)	0.62334 (10)	0.0537 (7)
H6	0.500 (4)	−0.373 (4)	0.6027 (13)	0.085 (15)*
O1	0.8667 (2)	0.1053 (2)	0.47674 (8)	0.0366 (5)
H1	0.929 (3)	0.066 (4)	0.4646 (16)	0.091 (16)*
O2	0.7236 (2)	−0.0726 (2)	0.51893 (10)	0.0413 (6)
H2	0.739 (5)	−0.149 (3)	0.5316 (16)	0.102 (18)*
O3	0.92807 (17)	−0.00007 (19)	0.56151 (7)	0.0279 (5)
O4	0.74292 (18)	0.17523 (19)	0.55177 (8)	0.0324 (5)
P1	0.81774 (6)	0.05253 (7)	0.52950 (3)	0.0242 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.050 (2)	0.093 (3)	0.057 (2)	−0.009 (2)	−0.0153 (19)	−0.020 (2)
C2	0.0434 (18)	0.050 (2)	0.0308 (17)	0.0091 (16)	−0.0039 (14)	0.0055 (15)
C3	0.0353 (15)	0.0273 (16)	0.0277 (16)	0.0039 (13)	0.0068 (13)	−0.0017 (12)
C4	0.064 (2)	0.045 (2)	0.0339 (19)	0.0084 (18)	0.0157 (17)	−0.0015 (16)
C5	0.094 (3)	0.063 (3)	0.043 (2)	0.002 (2)	0.006 (2)	−0.0247 (19)
C6	0.101 (4)	0.106 (4)	0.055 (3)	−0.017 (3)	−0.016 (3)	−0.035 (3)
C7	0.0310 (15)	0.0361 (18)	0.0317 (16)	0.0113 (13)	0.0044 (13)	0.0009 (13)
C8	0.0446 (19)	0.0364 (19)	0.052 (2)	−0.0021 (15)	0.0225 (17)	−0.0022 (15)
C9	0.0320 (16)	0.0271 (17)	0.044 (2)	−0.0051 (13)	0.0077 (14)	−0.0016 (14)
N1	0.0291 (14)	0.0331 (16)	0.0265 (14)	0.0046 (12)	0.0017 (11)	0.0030 (12)
O5	0.0501 (14)	0.0350 (13)	0.0399 (14)	0.0027 (10)	0.0078 (11)	−0.0013 (10)
O6	0.0788 (18)	0.0353 (15)	0.0471 (15)	0.0119 (13)	0.0221 (14)	0.0026 (12)
O1	0.0325 (11)	0.0383 (12)	0.0391 (13)	0.0121 (10)	0.0096 (10)	0.0117 (10)
O2	0.0331 (11)	0.0184 (12)	0.0724 (17)	−0.0029 (9)	−0.0180 (11)	0.0081 (11)
O3	0.0233 (9)	0.0249 (10)	0.0356 (11)	0.0022 (8)	0.0001 (8)	0.0001 (9)
O4	0.0273 (10)	0.0182 (10)	0.0516 (13)	0.0048 (8)	0.0121 (9)	0.0033 (9)
P1	0.0193 (3)	0.0157 (4)	0.0377 (4)	0.0022 (3)	0.0025 (3)	0.0031 (3)

Geometric parameters (Å, º) top

C1—C2	1.519 (5)	C7—N1	1.476 (4)
C1—C6	1.526 (6)	C7—H7A	0.9700
C1—H1A	0.9700	C7—H7B	0.9700
C1—H1B	0.9700	C8—C9	1.498 (4)
C2—C3	1.541 (4)	C8—H8A	0.9700
C2—H2A	0.9700	C8—H8B	0.9700
C2—H2B	0.9700	C9—O5	1.213 (3)
C3—C7	1.531 (4)	C9—O6	1.310 (4)
C3—C4	1.541 (4)	N1—H3	0.897 (18)
C3—C8	1.549 (4)	N1—H4	0.912 (18)
C4—C5	1.519 (5)	N1—H5	0.881 (18)
C4—H4A	0.9700	O6—H6	0.83 (4)
C4—H4B	0.9700	O1—P1	1.566 (2)
C5—C6	1.515 (6)	O1—H1	0.817 (19)
C5—H5A	0.9700	O2—P1	1.548 (2)
C5—H5B	0.9700	O2—H2	0.799 (19)
C6—H6A	0.9700	O3—P1	1.513 (2)
C6—H6B	0.9700	O4—P1	1.502 (2)

C2—C1—C6	111.5 (3)	C5—C6—H6B	109.5
C2—C1—H1A	109.3	C1—C6—H6B	109.5
C6—C1—H1A	109.3	H6A—C6—H6B	108.1
C2—C1—H1B	109.3	N1—C7—C3	115.2 (2)
C6—C1—H1B	109.3	N1—C7—H7A	108.5
H1A—C1—H1B	108.0	C3—C7—H7A	108.5
C1—C2—C3	113.1 (3)	N1—C7—H7B	108.5
C1—C2—H2A	109.0	C3—C7—H7B	108.5
C3—C2—H2A	109.0	H7A—C7—H7B	107.5
C1—C2—H2B	109.0	C9—C8—C3	117.0 (2)
C3—C2—H2B	109.0	C9—C8—H8A	108.0
H2A—C2—H2B	107.8	C3—C8—H8A	108.0
C7—C3—C2	112.5 (2)	C9—C8—H8B	108.0
C7—C3—C4	106.6 (2)	C3—C8—H8B	108.0
C2—C3—C4	108.6 (3)	H8A—C8—H8B	107.3
C7—C3—C8	111.3 (3)	O5—C9—O6	123.0 (3)
C2—C3—C8	110.5 (3)	O5—C9—C8	124.2 (3)
C4—C3—C8	107.1 (2)	O6—C9—C8	112.7 (3)
C5—C4—C3	114.7 (3)	C7—N1—H3	111 (2)
C5—C4—H4A	108.6	C7—N1—H4	111 (2)
C3—C4—H4A	108.6	H3—N1—H4	109 (3)
C5—C4—H4B	108.6	C7—N1—H5	112 (2)
C3—C4—H4B	108.6	H3—N1—H5	107 (3)
H4A—C4—H4B	107.6	H4—N1—H5	107 (3)
C6—C5—C4	110.7 (3)	C9—O6—H6	109 (3)
C6—C5—H5A	109.5	P1—O1—H1	118 (3)
C4—C5—H5A	109.5	P1—O2—H2	118 (3)
C6—C5—H5B	109.5	O4—P1—O3	115.00 (12)
C4—C5—H5B	109.5	O4—P1—O2	107.84 (12)
H5A—C5—H5B	108.1	O3—P1—O2	110.23 (12)
C5—C6—C1	110.8 (3)	O4—P1—O1	106.50 (11)
C5—C6—H6A	109.5	O3—P1—O1	110.49 (12)
C1—C6—H6A	109.5	O2—P1—O1	106.35 (14)

C6—C1—C2—C3	55.9 (4)	C2—C1—C6—C5	−56.5 (5)
C1—C2—C3—C7	65.8 (4)	C2—C3—C7—N1	53.0 (4)
C1—C2—C3—C4	−51.9 (4)	C4—C3—C7—N1	172.0 (3)
C1—C2—C3—C8	−169.2 (3)	C8—C3—C7—N1	−71.5 (3)
C7—C3—C4—C5	−69.4 (4)	C7—C3—C8—C9	80.2 (3)
C2—C3—C4—C5	52.0 (4)	C2—C3—C8—C9	−45.5 (4)
C8—C3—C4—C5	171.4 (3)	C4—C3—C8—C9	−163.7 (3)
C3—C4—C5—C6	−54.9 (4)	C3—C8—C9—O5	−61.3 (4)
C4—C5—C6—C1	55.2 (5)	C3—C8—C9—O6	120.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O6—H6···O3ⁱ	0.83 (4)	1.77 (2)	2.602 (3)	173 (4)
O1—H1···O3ⁱⁱ	0.82 (2)	1.76 (2)	2.569 (3)	173 (5)
N1—H5···O1ⁱⁱⁱ	0.88 (2)	2.26 (3)	2.929 (4)	133 (3)
N1—H5···O2^iv	0.88 (2)	2.44 (3)	2.959 (3)	118 (3)
N1—H5···O5^iv	0.88 (2)	2.47 (3)	3.065 (3)	125 (3)
N1—H4···O5	0.91 (2)	1.89 (2)	2.760 (4)	158 (3)
N1—H3···O4	0.90 (2)	1.86 (2)	2.752 (3)	174 (3)

Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) −x+2, −y, −z+1; (iii) x−1/2, −y+1/2, −z+1; (iv) −x+1, −y, −z+1.

Experimental details

Crystal data
Chemical formula	C₉H₁₈NO₂⁺·H₂O₄P⁻
M_r	269.23
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	296
a, b, c (Å)	10.473 (5), 9.269 (3), 26.468 (5)
V (Å³)	2569.4 (16)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.23
Crystal size (mm)	0.31 × 0.25 × 0.22

Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	14659, 3185, 1853
R_int	0.071
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.051, 0.155, 1.06
No. of reflections	3185
No. of parameters	178
No. of restraints	6
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.34, −0.45

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), 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
O6—H6···O3ⁱ	0.83 (4)	1.77 (2)	2.602 (3)	173 (4)
O1—H1···O3ⁱⁱ	0.817 (19)	1.76 (2)	2.569 (3)	173 (5)
N1—H5···O1ⁱⁱⁱ	0.881 (18)	2.26 (3)	2.929 (4)	133 (3)
N1—H5···O2^iv	0.881 (18)	2.44 (3)	2.959 (3)	118 (3)
N1—H5···O5^iv	0.881 (18)	2.47 (3)	3.065 (3)	125 (3)
N1—H4···O5	0.912 (18)	1.89 (2)	2.760 (4)	158 (3)
N1—H3···O4	0.897 (18)	1.858 (19)	2.752 (3)	174 (3)

Symmetry codes: (i) −x+3/2, y−1/2, z; (ii) −x+2, −y, −z+1; (iii) x−1/2, −y+1/2, −z+1; (iv) −x+1, −y, −z+1.

Acknowledgements

IUK thanks the Higher Education Commission of Pakistan for financial support under the project `Strengthening of the Materials Chemistry Laboratory' at GCUL.

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