Methyl 6-amino-6-oxohexa­noate

Gruber, T.; Schofield, C.J.; Thompson, A.L.

doi:10.1107/S1600536812003303

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 68| Part 3| March 2012| Pages o593-o594

doi:10.1107/S1600536812003303

Open

access

Methyl 6-amino-6-oxohexanoate

Tobias Gruber,^a ‡ Christopher J. Schofield ^a and Amber L. Thompson ^b ^*

^aChemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, England, and ^bChemical Crystallography, Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, England
^*Correspondence e-mail: amber.thompson@chem.ox.ac.uk

(Received 18 November 2011; accepted 25 January 2012; online 4 February 2012)

The title compound, C₇H₁₃NO₃, adopts an approximately planar conformation. The torsion angles in the aliphatic chain between the carbonyl group C atoms range from 172.97 (14) to 179.38 (14)° and the r.m.s. deviation of all non-H atoms is 0.059 Å. The crystal packing is dominated by two strong N—H⋯O hydrogen bonds involving the amide groups and forming R₂²(8) rings and C(4) chains. Overall, a two-dimensional network parallel to (100) is formed. A weak intermolecular C—H⋯O interaction is also present.

Related literature

For the synthesis of the title compound, see: Kulikova et al. (1960 ); Nishitani et al. (1982 ); Micovic et al. (1988 ). For information on the solid-state characteristics of different polymorphs of adipic acid, see: Fun & Chantrapromma (2009 ); Ranganathan et al. (2003 ); Srinivasa Gopalan et al. (1999 , 2000 ); Pfefer & Boistelle (2000 ); Housty & Hospital (1965 ); Arevalo & Canut (1961 ); Hirokawa (1950 ); Morrison & Robertson (1949 ); MacGillavry (1941 ). For details on co-crystals of the title compound, see: Goswami et al. (2010 ); Delori et al. (2008 ); Bucar et al. (2007 ); Childs & Hardcastle (2007 ); Duan et al. (2005 ); Li et al. (2001 ); Urbanczyk-Lipkowska & Gluzinski (1996 ). For other reports of adipic acid derivatives, see: Li & Goddard (2002 ); Seaton & Tremayne (2002 ); Hospital & Housty (1966 ). For uses of the title compound in heterocycle synthesis, see: Jungheim et al. (2005 ); Fukumoto et al. (2007 ). For hydrogen-bond motifs, see: Bernstein et al. (1995 ). For details of the H-atom treatment, see: Cooper et al. (2010 ).

Experimental

Crystal data

C₇H₁₃NO₃
M_r = 159.19
Monoclinic, P 2₁ /c
a = 12.896 (3) Å
b = 7.2143 (8) Å
c = 9.6324 (12) Å
β = 106.474 (17)°
V = 859.4 (2) Å³
Z = 4
Cu Kα radiation
μ = 0.80 mm⁻¹
T = 150 K
0.18 × 0.12 × 0.02 mm

Data collection

Agilent SuperNova Dual (Cu at zero) diffractometer with an Atlas detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ) T_min = 0.48, T_max = 0.98
7240 measured reflections
1771 independent reflections
1426 reflections with I > 2σ(I)
R_int = 0.035
Standard reflections: 0

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.128
S = 1.00
1770 reflections
100 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H31⋯O1ⁱ	0.86	2.07	2.929 (2)	173 (1)
N3—H32⋯O1ⁱⁱ	0.86	2.09	2.922 (2)	162 (1)
C10—H101⋯O11ⁱⁱⁱ	0.95	2.61	3.486 (3)	153 (1)
Symmetry codes: (i) -x, -y+3, -z+1; (ii) $[x, -y+{\script{5\over 2}}, z+{\script{1\over 2}}]$ ; (iii) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ); molecular graphics: CAMERON (Watkin et al., 1996 ); software used to prepare material for publication: CRYSTALS and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812003303/lh5383sup1.cif

Supporting information file. DOI: 10.1107/S1600536812003303/lh5383Isup2.cdx

Structure factors: contains datablock I. DOI: 10.1107/S1600536812003303/lh5383Isup3.hkl

Supporting information file. DOI: 10.1107/S1600536812003303/lh5383Isup4.cml

checkCIF report

Comment top

Adipic acid has importance in various industrial applications including the production of polyamides and polyurethanes. The solid state characteristics of different polymorphs of adipic acid have already been investigated intensively (Fun & Chantrapromma, 2009; Ranganathan et al., 2003; Srinivasa Gopalan et al., 2000; Pfefer & Boistelle, 2000; Srinivasa Gopalan et al., 1999; Housty & Hospital, 1965; Arevalo & Canut, 1961; Hirokawa, 1950; Morrison & Robertson, 1949; MacGillavry, 1941), as have adipic acid co-crystals (Goswami et al., 2010; Delori et al., 2008; Bucar et al., 2007; Childs & Hardcastle, 2007; Duan et al., 2005, Li et al., 2001; Urbanczyk-Lipkowska & Gluzinski, 1996). Reports on single-crystal X-ray structures of adipic acid derivatives have focused on the important nylon-based materials (Li & Goddard, 2002). Here we describe the structure of a simple adipic acid derivative, viz. methyl 6-amino-6-oxohexanoate (I), an approved starting material for heterocyclic synthesis (Jungheim et al., 2005; Fukumoto et al., 2007).

Methyl 6-amino-6-oxohexanoate (I) crystallizes from methanol as colourless crystals in the monoclinic space group P2₁/c (Fig. 1). The molecule is approximately planar; the largest deviation from the mean plane defined by the non-hydrogen atoms is 0.116 Å for carbonyl oxygen O1 and the aliphatic chain between the carbonyl carbons is only slightly twisted with torsion angles ranging from 172.97 (14) to 179.38 (14)°. The crystal packing is dominated by two strong N—H···O hydrogen bonds (see Table 1), similar to those seen in the two polymorphs of adipamide (monoclinic: Hospital & Housty, 1966; triclinic: Seaton & Tremayne, 2002). In (I), the the amide nitrogen in serves as a double intermolecular hydrogen donor: N3—H31···O1ⁱ forms an R₂²(8) amide dimer around an inversion centre, while N3—H32···O1ⁱⁱ connects pairs of dimers to form C(4) chains parallel to the c axis. The combination of the C(4) and R₂²(8) motifs generates a secondary network of R₁₀⁶(24) as described for related compounds including benzamide etc. (Bernstein et al. (1995); Fig. 2).

Notably, the methyl ester carbonyl group is not involved in hydrogen bonding, however, it is in a suitable position to engage in a weak C—H···O intermolecular interaction with an ester methyl group [d(H···O) = 2.614 (3) Å].

In conclusion, the structure of (I), together with those similar and previously reported, suggest that the variation in the carbonyl substituent at adipic acid does not cause substantial changes to the conformation of the molecule.

Related literature top

For the synthesis of the title compound, see: Kulikova et al. (1960); Nishitani et al. (1982); Micovic et al. (1988). For information on the solid-state characteristics of different polymorphs of adipic acid, see: Fun & Chantrapromma (2009); Ranganathan et al. (2003); Srinivasa Gopalan et al. (1999, 2000); Pfefer & Boistelle (2000); Housty & Hospital (1965); Arevalo & Canut (1961); Hirokawa (1950); Morrison & Robertson (1949); MacGillavry (1941). For details on co-crystals of the title compound, see: Goswami et al. (2010); Delori et al. (2008); Bucar et al. (2007); Childs & Hardcastle (2007); Duan et al. (2005); Li et al. (2001); Urbanczyk-Lipkowska & Gluzinski (1996). For other reports of adipic acid derivatives, see: Li & Goddard (2002); Seaton & Tremayne (2002); Hospital & Housty (1966). For uses of the title compound in heterocycle synthesis, see: Jungheim et al. (2005); Fukumoto et al. (2007). For hydrogen-bond motifs, see: Bernstein et al. (1995). For details of the H-atom treatment, see: Cooper et al. (2010).

Experimental top

The title compound was recovered as a side product in 0.5% yield from the cyclization reaction of amino pimelic acid methylester in p-cymene via a redox process (Nishitani et al., 1982). Crystals suitable for X-ray diffraction were obtained by slow evaporation of a solution of the compound in methanol.

Alternatively, the title compound can also preprared by reaction of the respective acid chloride with ammonia (Micovic et al., 1988) and the partial hydrolysis of the corresponding nitrile (Kulikova et al., 1960).

Computing details top

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003) and PLATON (Spek, 2009).

Figures top

	Fig. 1. Molecular structure of (I) with displacement ellipsoids drawn at 50% probability.
	Fig. 2. Hydrogen bonding in the crystal structure of (I) [i: -x,3 - y,1 - z; ii: x,5/2 - y,-1/2 + z; iii: x,5/2 - y,1/2 + z].

Methyl 6-amino-6-oxohexanoate top

Crystal data top

C₇H₁₃NO₃	F(000) = 344
M_r = 159.19	D_x = 1.230 Mg m⁻³
Monoclinic, P2₁/c	Melting point: not measured K
Hall symbol: -P 2ybc	Cu Kα radiation, λ = 1.54184 Å
a = 12.896 (3) Å	Cell parameters from 2081 reflections
b = 7.2143 (8) Å	θ = 4–76°
c = 9.6324 (12) Å	µ = 0.80 mm⁻¹
β = 106.474 (17)°	T = 150 K
V = 859.4 (2) Å³	Lath, clear_pale_colourless
Z = 4	0.18 × 0.12 × 0.02 mm

Data collection top

Agilent SuperNova Dual (Cu at zero) diffractometer with an Atlas detector	1426 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
ω scans	θ_max = 76.0°, θ_min = 3.6°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	h = −16→15
T_min = 0.48, T_max = 0.98	k = −9→7
7240 measured reflections	l = −12→11
1771 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.044	H-atom parameters constrained
wR(F²) = 0.128	Method = Modified Sheldrick w = 1/[σ²(F²) + ( 0.07P)² + 0.22P], where P = (max(F_o²,0) + 2F_c²)/3
S = 1.00	(Δ/σ)_max = 0.001
1770 reflections	Δρ_max = 0.24 e Å⁻³
100 parameters	Δρ_min = −0.24 e Å⁻³
0 restraints

Crystal data top

C₇H₁₃NO₃	V = 859.4 (2) Å³
M_r = 159.19	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 12.896 (3) Å	µ = 0.80 mm⁻¹
b = 7.2143 (8) Å	T = 150 K
c = 9.6324 (12) Å	0.18 × 0.12 × 0.02 mm
β = 106.474 (17)°

Data collection top

Agilent SuperNova Dual (Cu at zero) diffractometer with an Atlas detector	1771 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	1426 reflections with I > 2σ(I)
T_min = 0.48, T_max = 0.98	R_int = 0.035
7240 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.128	H-atom parameters constrained
S = 1.00	Δρ_max = 0.24 e Å⁻³
1770 reflections	Δρ_min = −0.24 e Å⁻³
100 parameters

Special details top

Experimental. Agilent Technologies (2010). CrysAlisPro. Version 1.171.35.4 (release 09-12-2010 CrysAlis171 .NET) (compiled Dec 9 2010,10:47:41) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

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

	x	y	z	U_iso*/U_eq
O1	0.07129 (11)	1.29877 (15)	0.44865 (11)	0.0413
C2	0.09105 (12)	1.2640 (2)	0.58008 (14)	0.0323
N3	0.05751 (12)	1.37331 (17)	0.66941 (12)	0.0372
H31	0.0242	1.4758	0.6389	0.0445*
H32	0.0717	1.3426	0.7589	0.0449*
C4	0.15519 (14)	1.0967 (2)	0.64774 (15)	0.0380
C5	0.18119 (13)	0.9615 (2)	0.54141 (15)	0.0339
C6	0.24703 (14)	0.7987 (2)	0.62007 (15)	0.0373
C7	0.27433 (15)	0.6613 (2)	0.51664 (17)	0.0417
C8	0.34505 (14)	0.5046 (2)	0.59123 (17)	0.0411
O9	0.36947 (12)	0.39151 (19)	0.49492 (14)	0.0571
C10	0.43990 (18)	0.2384 (3)	0.5546 (2)	0.0604
H101	0.4474	0.1631	0.4773	0.0899*
H103	0.5097	0.2837	0.6123	0.0882*
H102	0.4069	0.1646	0.6164	0.0903*
O11	0.37696 (14)	0.48159 (19)	0.71881 (14)	0.0605
H71	0.3122	0.7249	0.4570	0.0507*
H72	0.2080	0.6062	0.4549	0.0501*
H62	0.3138	0.8436	0.6854	0.0443*
H61	0.2066	0.7354	0.6763	0.0458*
H52	0.2233	1.0258	0.4878	0.0396*
H51	0.1133	0.9163	0.4743	0.0412*
H41	0.2227	1.1408	0.7133	0.0470*
H42	0.1152	1.0285	0.7024	0.0471*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0675 (8)	0.0363 (6)	0.0230 (5)	0.0117 (5)	0.0176 (5)	0.0041 (4)
C2	0.0438 (8)	0.0298 (7)	0.0251 (6)	−0.0007 (6)	0.0126 (6)	0.0004 (5)
N3	0.0586 (8)	0.0333 (6)	0.0223 (5)	0.0073 (6)	0.0154 (5)	0.0023 (4)
C4	0.0549 (9)	0.0355 (8)	0.0247 (6)	0.0069 (7)	0.0133 (6)	0.0033 (5)
C5	0.0441 (8)	0.0312 (7)	0.0269 (6)	0.0011 (6)	0.0109 (5)	−0.0001 (5)
C6	0.0521 (9)	0.0317 (7)	0.0281 (7)	0.0030 (6)	0.0112 (6)	0.0006 (5)
C7	0.0532 (9)	0.0378 (8)	0.0327 (7)	0.0066 (7)	0.0100 (7)	−0.0031 (6)
C8	0.0461 (9)	0.0330 (8)	0.0408 (8)	−0.0015 (6)	0.0070 (7)	−0.0036 (6)
O9	0.0645 (8)	0.0499 (7)	0.0489 (7)	0.0206 (6)	0.0031 (6)	−0.0128 (5)
C10	0.0552 (11)	0.0471 (10)	0.0707 (13)	0.0130 (9)	0.0046 (9)	−0.0113 (9)
O11	0.0857 (10)	0.0492 (7)	0.0424 (7)	0.0185 (7)	0.0111 (7)	0.0068 (5)

Geometric parameters (Å, º) top

O1—C2	1.2441 (18)	C6—H62	0.967
C2—N3	1.3269 (19)	C6—H61	0.966
C2—C4	1.503 (2)	C7—C8	1.501 (2)
N3—H31	0.864	C7—H71	0.969
N3—H32	0.858	C7—H72	0.977
C4—C5	1.5193 (19)	C8—O9	1.338 (2)
C4—H41	0.972	C8—O11	1.192 (2)
C4—H42	0.970	O9—C10	1.442 (2)
C5—C6	1.520 (2)	C10—H101	0.949
C5—H52	0.967	C10—H103	0.971
C5—H51	0.984	C10—H102	0.981
C6—C7	1.516 (2)

O1—C2—N3	121.98 (13)	C7—C6—H62	108.5
O1—C2—C4	122.14 (13)	C5—C6—H61	109.3
N3—C2—C4	115.88 (12)	C7—C6—H61	108.8
C2—N3—H31	120.7	H62—C6—H61	108.4
C2—N3—H32	118.8	C6—C7—C8	113.61 (13)
H31—N3—H32	120.4	C6—C7—H71	109.3
C2—C4—C5	115.01 (11)	C8—C7—H71	107.5
C2—C4—H41	107.5	C6—C7—H72	109.9
C5—C4—H41	108.7	C8—C7—H72	107.0
C2—C4—H42	109.3	H71—C7—H72	109.5
C5—C4—H42	107.1	C7—C8—O9	110.96 (14)
H41—C4—H42	109.2	C7—C8—O11	125.70 (15)
C4—C5—C6	111.05 (12)	O9—C8—O11	123.34 (16)
C4—C5—H52	108.5	C8—O9—C10	115.85 (15)
C6—C5—H52	108.5	O9—C10—H101	108.6
C4—C5—H51	109.3	O9—C10—H103	110.4
C6—C5—H51	109.8	H101—C10—H103	110.9
H52—C5—H51	109.7	O9—C10—H102	109.0
C5—C6—C7	112.25 (12)	H101—C10—H102	108.9
C5—C6—H62	109.5	H103—C10—H102	109.1

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N3—H31···O1ⁱ	0.86	2.07	2.929 (2)	173 (1)
N3—H32···O1ⁱⁱ	0.86	2.09	2.922 (2)	162 (1)
C10—H101···O11ⁱⁱⁱ	0.95	2.61	3.486 (3)	153 (1)

Symmetry codes: (i) −x, −y+3, −z+1; (ii) x, −y+5/2, z+1/2; (iii) x, −y+1/2, z−1/2.

Experimental details

Crystal data
Chemical formula	C₇H₁₃NO₃
M_r	159.19
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	150
a, b, c (Å)	12.896 (3), 7.2143 (8), 9.6324 (12)
β (°)	106.474 (17)
V (Å³)	859.4 (2)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.80
Crystal size (mm)	0.18 × 0.12 × 0.02

Data collection
Diffractometer	Agilent SuperNova Dual (Cu at zero) diffractometer with an Atlas detector
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2010)
T_min, T_max	0.48, 0.98
No. of measured, independent and observed [I > 2σ(I)] reflections	7240, 1771, 1426
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.629

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.128, 1.00
No. of reflections	1770
No. of parameters	100
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.24

Computer programs: CrysAlis PRO (Agilent, 2010), SIR92 (Altomare et al., 1994), CAMERON (Watkin et al., 1996), CRYSTALS (Betteridge et al., 2003) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N3—H31···O1ⁱ	0.86366	2.069	2.929 (2)	172.95 (5)
N3—H32···O1ⁱⁱ	0.85792	2.094	2.922 (2)	161.75 (5)
C10—H101···O11ⁱⁱⁱ	0.94863	2.614	3.486 (3)	153.02 (6)

Symmetry codes: (i) −x, −y+3, −z+1; (ii) x, −y+5/2, z+1/2; (iii) x, −y+1/2, z−1/2.

Footnotes

‡Present address: Institut für Organische Chemie, TU Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

Acknowledgements

TG thanks Deutsche Forschungsgemeinschaft (DFG), Germany, for generous funding (GR 3693/1–1:1).

References

Agilent (2010). CrysAlis PRO. Agilent Technologies, Yarnton, Oxfordshire, England. Google Scholar
Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. CrossRef Web of Science IUCr Journals Google Scholar
Arevalo, M. I. & Canut, M. L. (1961). Bol. R. Soc. Esp. Hist. Nat. (Sec. Geol.), 59, 37–40. CAS Google Scholar
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487. Web of Science CrossRef IUCr Journals Google Scholar
Bucar, D.-K., Henry, R. F., Lou, X., Borchardt, T. B. & Zhang, G. G. Z. (2007). Chem. Commun. pp. 525–527. Google Scholar
Childs, S. L. & Hardcastle, K. I. (2007). Cryst. Growth Des. 7, 1291–1304. Web of Science CSD CrossRef CAS Google Scholar
Cooper, R. I., Thompson, A. L. & Watkin, D. J. (2010). J. Appl. Cryst. 43, 1100–1107. Web of Science CrossRef CAS IUCr Journals Google Scholar
Delori, A., Suresh, E. & Pedireddi, V. R. (2008). Chem. Eur. J. 14, 6967–6977. Web of Science CSD CrossRef PubMed CAS Google Scholar
Duan, L.-M., Ye, L., Liu, Y.-B., Xie, F.-T., Yu, J.-H. & Xu, J.-Q. (2005). Pol. J. Chem. 79, 1835–1842. CAS Google Scholar
Fukumoto, S., Matsunaga, N., Ohra, T., Ohyabu, N., Hasui, T., Motoyaji, T., Siedem, C. S., Tang, T. P., Demeese, L. A. & Gauthier, C. (2007). PCT Int. Appl. 2007077961. Google Scholar
Fun, H.-K. & Chantrapromma, S. (2009). Acta Cryst. E65, o624. Web of Science CSD CrossRef IUCr Journals Google Scholar
Goswami, S., Hazra, A. & Fun, H.-K. (2010). J. Inclusion Phenom. 68, 461–466. CrossRef CAS Google Scholar
Hirokawa, S. (1950). Bull. Chem. Soc. Jpn, 23, 91–94. CrossRef CAS Google Scholar
Hospital, M. & Housty, J. (1966). Acta Cryst. 20, 626–630. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
Housty, J. & Hospital, M. (1965). Acta Cryst. 18, 693–697. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
Jungheim, L. N., McGill, J. M., Trasher, K. J., Herr, R. J. & Muralikrishna, V. (2005). PCT Int. Appl. 2005019184. Google Scholar
Kulikova, A. E., Zil'berman, E. N. & Sazanova, N. A. (1960). Zh. Obshch. Khim. 30, 2180–2183. CAS Google Scholar
Li, Y. & Goddard, W. A. (2002). Macromolecules, 35, 8440–8455. Web of Science CrossRef CAS Google Scholar
Li, W., Zhang, J.-P., Tong, M.-L. & Chen, X.-M. (2001). Aust. J. Chem. 54, 213–217. Web of Science CSD CrossRef Google Scholar
MacGillavry, C. H. (1941). Recl Trav. Chim. Pays-Bas, 60, 605–617. CAS Google Scholar
Micovic, V., Ivanovic, M. D. & Piatak, D. M. (1988). J. Serb. Chem. Soc. 53, 419–426. CAS Google Scholar
Morrison, J. D. & Robertson, J. M. (1949). J. Chem. Soc. pp. 987–92. CrossRef Web of Science Google Scholar
Nishitani, T., Horikawa, H., Iwasaki, T., Matsumoto, K., Inoue, I. & Miyoshi, M. (1982). J. Org. Chem. 47, 1706–1712. CrossRef CAS Web of Science Google Scholar
Pfefer, G. & Boistelle, R. (2000). J. Cryst. Growth, 208, 615–622. Web of Science CrossRef CAS Google Scholar
Ranganathan, A., Kulkarni, G. U. & Rao, C. N. R. (2003). J. Phys. Chem. A, 107, 6073–6081. Web of Science CSD CrossRef CAS Google Scholar
Seaton, C. C. & Tremayne, M. (2002). Chem. Commun. pp. 880–881. Web of Science CSD CrossRef Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Srinivasa Gopalan, R., Kumaradhas, P. & Kulkarni, G. U. (1999). J. Solid State Chem. 148, 129–134. CSD CrossRef CAS Google Scholar
Srinivasa Gopalan, R., Kumaradhas, P., Kulkarni, G. U. & Rao, C. N. R. (2000). J. Mol. Struct. 521, 97–106. CSD CrossRef CAS Google Scholar
Urbanczyk-Lipkowska, Z. & Gluzinski, P. (1996). Supramol. Chem. 7, 113–118. CAS Google Scholar
Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England. Google Scholar