rac-N-{6-[Bromo­(hydr­oxy)meth­yl]-2-pyrid­yl}pivalamide

Knight, J.C.; Saad, F.A.; Amoroso, A.J.; Kariuki, B.M.; Coles, S.J.

doi:10.1107/S1600536809006795

organic compounds

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Volume 65| Part 3| March 2009| Page o647

doi:10.1107/S1600536809006795

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rac-N-{6-[Bromo(hydroxy)methyl]-2-pyridyl}pivalamide

James C. Knight,^a ^* Fawaz A. Saad,^a Angelo J. Amoroso,^a Benson M. Kariuki ^a and Simon J. Coles ^b

^aMain Building, School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales, and ^bSchool of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, England
^*Correspondence e-mail: knightjc@cardiff.ac.uk

(Received 21 February 2009; accepted 24 February 2009; online 28 February 2009)

The title compound, C₁₁H₁₅BrN₂O₂, contains an amide group which is close to coplanar with the adjacent pyridine ring, the dihedral angle between the planes being 9.0 (5)°. The molecular packing reveals a mutual hydrogen-bond interaction between centrosymmetrically related hydroxyl O atoms. Further hydrogen bonding involving O—H⋯Br and N—H⋯Br interactions also appears to consolidate the packing.

Related literature

For a related structure, see: Goswami et al. (2005 ). For the synthesis, see Harata et al. (1995 ).

Experimental

Crystal data

C₁₁H₁₅BrN₂O₂
M_r = 287.16
Monoclinic, P 2₁ /c
a = 13.2980 (5) Å
b = 10.0848 (3) Å
c = 9.4890 (3) Å
β = 106.858 (1)°
V = 1217.86 (7) Å³
Z = 4
Mo Kα radiation
μ = 3.36 mm⁻¹
T = 150 K
0.10 × 0.08 × 0.08 mm

Data collection

Bruker–Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ) T_min = 0.730, T_max = 0.771
11933 measured reflections
2773 independent reflections
2142 reflections with I > 2σ(I)
R_int = 0.081

Refinement

R[F² > 2σ(F²)] = 0.060
wR(F²) = 0.166
S = 1.10
2773 reflections
149 parameters
H-atom parameters constrained
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.99 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O1ⁱ	0.84	2.03	2.472 (10)	113
O1—H1A⋯Br1ⁱⁱ	0.84	2.85	3.509 (5)	137
N2—H2⋯Br1ⁱⁱ	0.88	2.97	3.690 (4)	140
Symmetry codes: (i) -x+1, -y, -z+1; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Data collection: COLLECT (Nonius, 2000 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ) and CHEMDRAW Ultra (Cambridge Soft 2001).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809006795/sj2584sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809006795/sj2584Isup2.hkl

checkCIF report

Comment top

During research focused on new synthetic routes towards novel poly-pyridyl co-ordination compounds, we observed an unexpected by-product in one of our syntheses. As we attempted to prepare N-(6-(bromomethyl)pyridin-2-yl)pivalamide (1) from N-(6-methylpyridin-2-yl)pivalamide and N-bromosuccinimide (NBS) in the presence of azobisisobutyronitrile (AIBN) (Harata et al., 1995), the title compound (2) was isolated in low yield (Fig. 3).

We postulate that during the free-radical driven mono-bromination reaction (Scheme 2), a small quantity of N-(6-(dibromomethyl)pyridin-2-yl)pivalamide is generated. The formation of 2 would proceed via an S_N1 reaction involving water, arising as a minor contaminant within the solvent. Subsequent elimination of HBr would lead to the formation of the corresponding aldehyde, however, we have isolated this intermediate prior to HBr elimination.

The formation of the stereogenic centre (C1) from achiral starting materials without any optically active agent has naturally led to a racemic compound. The geometry surrounding the C1 atom is a distorted tetrahedron, which supports the sp³-hybridization of this carbon, and the comparatively long C1–O1 bond (1.440 (8) Å) confirms the presence of an alcohol rather than a ketone. Additionally, while no hydroxyl proton was observed in the ¹H NMR, the spectrum revealed a diagnostic singlet at a considerable downfield shift of 6.40 p.p.m. which, according to the ¹H NMR prediction software (CHEMDRAW Ultra 8.0; Cambridge Soft 2001), is indicative of a proton (H1) in an α-position to a hydroxyl group and a bromine atom. The single-crystal infrared spectrum of this compound also features just a single band in the carbonyl region (1694.0 cm^-1) attributable to the amide carbonyl stretch. The bond lengths and angles of the title compound are in good agreement with the expected values (Goswami et al., 2005).

The mutual H-bond interaction between hydroxyl oxygen atoms O1 and O1ⁱ (Fig. 2) results in a short H···H distance (1.87 Å) which is indicative of some disorder between the hydroxyl groups. Attempts at modeling this disorder have given unsatisfactory results. See Table 1 for details of other H-bond interactions which support the crystal packing (Fig. 3).

Related literature top

For a related structure, see, for example: Goswami et al. (2005). For synthetic procedures, see Harata et al. (1995).

Experimental top

N-(6-methylpyridin-2-yl)pivalamide (40 g, 0.207 mol), NBS (56 g, 0.315 mol), and a catalytic amount of AIBN were dissolved in carbon tetrachloride (400 ml). The reaction mixture was heated at reflux for 13 h. The resulting crude brown oil was purified via column chromatography (hexane:ethyl acetate (95:5)). Recrystallization from hexane afforded crystals (yield 1.7%) suitable for X-ray diffraction. ¹H NMR (400 MHz; CDCl₃): 7.94 (s, 1H, H2), 7.92 (d, 1H, J = 7.87 Hz, py-H5), 7.70 (t, 1H, J = 7.89 Hz, py-H4), 7.37 (d, 1H, J = 7.60 Hz, py-H3), 6.40 (s, 1H, H1), 1.27 (s, 9H, H9–11). IR (KBr disk): 1694.0 cm^-1 (—C=O). HRMS (EI) m/z: calc. for C₁₁H₁₅BrN₂O 270.0368, found 270.0373.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999) and CHEMDRAW Ultra (Cambridge Soft 2001).

Figures top

	Fig. 1. Molecular structure of the title compound, showing the atom numbering. Displacement ellipsoids are drawn at the 50% probablility level. H atoms are represented by circles of arbitrary size.
	Fig. 2. A view showing the mutual H-bond interaction between centrosymmetrically related hydroxyl oxygen atoms O1 and O1ⁱ. A short H···H distance is suggestive of unresolved synchronized disorder between these groups. The hydrogen atom is also involved in H-bonding with a bromine acceptor atom located on a different molecule. [symmetry code (i): 1 - x, y - 1/2, 3/2 - z.]
	Fig. 3. A view of the molecular packing. H-bonding interactions are indicated by a dashed line. Displacement ellipsoids are drawn at the 50% probablility level. H atoms are represented by circles of arbitrary size.
	Fig. 4. Preparation of the title compound.

rac-N-{6-[Bromo(hydroxy)methyl]-2-pyridyl}pivalamide top

Crystal data top

C₁₁H₁₅BrN₂O₂	F(000) = 584
M_r = 287.16	D_x = 1.566 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 9199 reflections
a = 13.2980 (5) Å	θ = 2.9–27.5°
b = 10.0848 (3) Å	µ = 3.36 mm⁻¹
c = 9.4890 (3) Å	T = 150 K
β = 106.858 (1)°	Prism, colourless
V = 1217.86 (7) Å³	0.10 × 0.08 × 0.08 mm
Z = 4

Data collection top

Bruker–Nonius KappaCCD diffractometer	2773 independent reflections
Radiation source: fine-focus sealed tube	2142 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.081
Detector resolution: 9 pixels mm^-1	θ_max = 27.5°, θ_min = 3.0°
ϕ and ω scans	h = −17→17
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −13→13
T_min = 0.730, T_max = 0.771	l = −12→12
11933 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.060	H-atom parameters constrained
wR(F²) = 0.166	w = 1/[σ²(F_o²) + (0.0702P)² + 2.6431P] where P = (F_o² + 2F_c²)/3
S = 1.10	(Δ/σ)_max = 0.001
2773 reflections	Δρ_max = 0.53 e Å⁻³
149 parameters	Δρ_min = −0.99 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.011 (2)

Crystal data top

C₁₁H₁₅BrN₂O₂	V = 1217.86 (7) Å³
M_r = 287.16	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 13.2980 (5) Å	µ = 3.36 mm⁻¹
b = 10.0848 (3) Å	T = 150 K
c = 9.4890 (3) Å	0.10 × 0.08 × 0.08 mm
β = 106.858 (1)°

Data collection top

Bruker–Nonius KappaCCD diffractometer	2773 independent reflections
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	2142 reflections with I > 2σ(I)
T_min = 0.730, T_max = 0.771	R_int = 0.081
11933 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.060	0 restraints
wR(F²) = 0.166	H-atom parameters constrained
S = 1.10	Δρ_max = 0.53 e Å⁻³
2773 reflections	Δρ_min = −0.99 e Å⁻³
149 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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	0.4573 (5)	0.1876 (6)	0.5557 (7)	0.0503 (14)
H1	0.4497	0.2093	0.4503	0.060*
C2	0.3456 (4)	0.1520 (5)	0.5509 (5)	0.0377 (11)
C3	0.2616 (5)	0.1806 (5)	0.4307 (5)	0.0420 (12)
H3	0.2718	0.2221	0.3460	0.050*
C4	0.1622 (4)	0.1473 (5)	0.4365 (6)	0.0428 (12)
H4	0.1027	0.1675	0.3558	0.051*
C5	0.1492 (4)	0.0846 (5)	0.5600 (5)	0.0357 (11)
H5	0.0814	0.0615	0.5662	0.043*
C6	0.2389 (3)	0.0566 (4)	0.6742 (5)	0.0285 (9)
C7	0.1548 (3)	−0.0513 (4)	0.8487 (5)	0.0304 (10)
C8	0.1806 (4)	−0.1281 (5)	0.9947 (5)	0.0344 (11)
C9	0.0890 (5)	−0.2212 (7)	0.9885 (8)	0.0646 (19)
H9A	0.1061	−0.2764	1.0772	0.097*
H9B	0.0763	−0.2780	0.9013	0.097*
H9C	0.0259	−0.1689	0.9829	0.097*
C10	0.2806 (5)	−0.2096 (6)	1.0243 (6)	0.0511 (14)
H10A	0.3407	−0.1503	1.0345	0.077*
H10B	0.2750	−0.2707	0.9421	0.077*
H10C	0.2906	−0.2603	1.1154	0.077*
C11	0.1918 (6)	−0.0255 (7)	1.1159 (6)	0.0621 (17)
H11A	0.2044	−0.0707	1.2109	0.093*
H11B	0.1271	0.0268	1.0961	0.093*
H11C	0.2511	0.0332	1.1189	0.093*
N1	0.3360 (3)	0.0902 (4)	0.6727 (4)	0.0344 (9)
N2	0.2386 (3)	−0.0119 (4)	0.8029 (4)	0.0319 (9)
H2	0.3009	−0.0323	0.8622	0.038*
O1	0.5396 (4)	0.0896 (5)	0.5873 (5)	0.0644 (12)
H1A	0.5149	0.0157	0.6012	0.097*
O2	0.0655 (3)	−0.0259 (4)	0.7793 (4)	0.0514 (10)
Br1	0.49376 (4)	0.36048 (6)	0.65166 (6)	0.0461 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.054 (3)	0.056 (3)	0.051 (3)	−0.015 (3)	0.031 (3)	−0.010 (3)
C2	0.048 (3)	0.033 (3)	0.036 (2)	−0.012 (2)	0.019 (2)	−0.007 (2)
C3	0.061 (3)	0.036 (3)	0.030 (2)	−0.011 (2)	0.015 (2)	0.001 (2)
C4	0.047 (3)	0.043 (3)	0.030 (2)	0.000 (2)	−0.001 (2)	0.005 (2)
C5	0.033 (2)	0.032 (2)	0.037 (3)	−0.003 (2)	0.003 (2)	0.000 (2)
C6	0.026 (2)	0.028 (2)	0.031 (2)	−0.0052 (17)	0.0074 (17)	−0.0011 (18)
C7	0.030 (2)	0.028 (2)	0.034 (2)	0.0002 (18)	0.0111 (19)	−0.0038 (19)
C8	0.030 (2)	0.038 (3)	0.036 (2)	−0.001 (2)	0.012 (2)	0.007 (2)
C9	0.045 (3)	0.068 (4)	0.081 (5)	−0.010 (3)	0.018 (3)	0.036 (4)
C10	0.050 (3)	0.054 (4)	0.049 (3)	0.009 (3)	0.015 (3)	0.019 (3)
C11	0.088 (5)	0.060 (4)	0.040 (3)	0.012 (4)	0.022 (3)	0.003 (3)
N1	0.033 (2)	0.039 (2)	0.034 (2)	−0.0047 (17)	0.0135 (17)	0.0003 (18)
N2	0.0209 (17)	0.043 (2)	0.0293 (19)	0.0010 (16)	0.0028 (14)	0.0090 (17)
O1	0.061 (3)	0.055 (3)	0.084 (3)	−0.004 (2)	0.032 (2)	0.004 (2)
O2	0.0238 (17)	0.083 (3)	0.046 (2)	−0.0002 (18)	0.0081 (15)	0.018 (2)
Br1	0.0413 (4)	0.0561 (4)	0.0409 (3)	−0.0175 (2)	0.0118 (2)	0.0002 (2)

Geometric parameters (Å, º) top

C1—O1	1.440 (8)	C7—C8	1.536 (7)
C1—C2	1.516 (7)	C8—C10	1.518 (7)
C1—Br1	1.962 (6)	C8—C11	1.522 (8)
C1—H1	1.0000	C8—C9	1.526 (7)
C2—N1	1.352 (6)	C9—H9A	0.9800
C2—C3	1.376 (8)	C9—H9B	0.9800
C3—C4	1.380 (8)	C9—H9C	0.9800
C3—H3	0.9500	C10—H10A	0.9800
C4—C5	1.386 (7)	C10—H10B	0.9800
C4—H4	0.9500	C10—H10C	0.9800
C5—C6	1.388 (6)	C11—H11A	0.9800
C5—H5	0.9500	C11—H11B	0.9800
C6—N1	1.339 (6)	C11—H11C	0.9800
C6—N2	1.404 (6)	N2—H2	0.8800
C7—O2	1.207 (6)	O1—H1A	0.8400
C7—N2	1.367 (6)

O1—C1—C2	121.5 (5)	C10—C8—C7	113.2 (4)
O1—C1—Br1	116.2 (4)	C11—C8—C7	106.7 (4)
C2—C1—Br1	109.4 (4)	C9—C8—C7	107.9 (4)
O1—C1—H1	102.0	C8—C9—H9A	109.5
C2—C1—H1	102.0	C8—C9—H9B	109.5
Br1—C1—H1	102.0	H9A—C9—H9B	109.5
N1—C2—C3	123.4 (5)	C8—C9—H9C	109.5
N1—C2—C1	114.7 (5)	H9A—C9—H9C	109.5
C3—C2—C1	121.9 (5)	H9B—C9—H9C	109.5
C2—C3—C4	118.2 (5)	C8—C10—H10A	109.5
C2—C3—H3	120.9	C8—C10—H10B	109.5
C4—C3—H3	120.9	H10A—C10—H10B	109.5
C3—C4—C5	120.0 (5)	C8—C10—H10C	109.5
C3—C4—H4	120.0	H10A—C10—H10C	109.5
C5—C4—H4	120.0	H10B—C10—H10C	109.5
C4—C5—C6	117.6 (5)	C8—C11—H11A	109.5
C4—C5—H5	121.2	C8—C11—H11B	109.5
C6—C5—H5	121.2	H11A—C11—H11B	109.5
N1—C6—C5	123.6 (4)	C8—C11—H11C	109.5
N1—C6—N2	112.3 (4)	H11A—C11—H11C	109.5
C5—C6—N2	124.1 (4)	H11B—C11—H11C	109.5
O2—C7—N2	121.9 (4)	C6—N1—C2	117.2 (4)
O2—C7—C8	121.8 (4)	C7—N2—C6	128.9 (4)
N2—C7—C8	116.3 (4)	C7—N2—H2	115.6
C10—C8—C11	109.9 (5)	C6—N2—H2	115.6
C10—C8—C9	108.7 (5)	C1—O1—H1A	109.5
C11—C8—C9	110.4 (5)

O1—C1—C2—N1	53.7 (7)	O2—C7—C8—C11	−88.7 (6)
Br1—C1—C2—N1	−86.3 (5)	N2—C7—C8—C11	90.4 (5)
O1—C1—C2—C3	−126.0 (6)	O2—C7—C8—C9	30.0 (7)
Br1—C1—C2—C3	93.9 (5)	N2—C7—C8—C9	−150.9 (5)
N1—C2—C3—C4	1.7 (8)	C5—C6—N1—C2	−1.6 (7)
C1—C2—C3—C4	−178.7 (5)	N2—C6—N1—C2	177.4 (4)
C2—C3—C4—C5	−1.2 (8)	C3—C2—N1—C6	−0.3 (7)
C3—C4—C5—C6	−0.5 (8)	C1—C2—N1—C6	−180.0 (4)
C4—C5—C6—N1	2.0 (7)	O2—C7—N2—C6	−2.2 (8)
C4—C5—C6—N2	−176.9 (5)	C8—C7—N2—C6	178.7 (4)
O2—C7—C8—C10	150.3 (5)	N1—C6—N2—C7	173.7 (4)
N2—C7—C8—C10	−30.6 (6)	C5—C6—N2—C7	−7.3 (8)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O1ⁱ	0.84	2.03	2.472 (10)	113
O1—H1A···Br1ⁱⁱ	0.84	2.85	3.509 (5)	137
N2—H2···Br1ⁱⁱ	0.88	2.97	3.690 (4)	140

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

Experimental details

Crystal data
Chemical formula	C₁₁H₁₅BrN₂O₂
M_r	287.16
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	150
a, b, c (Å)	13.2980 (5), 10.0848 (3), 9.4890 (3)
β (°)	106.858 (1)
V (Å³)	1217.86 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	3.36
Crystal size (mm)	0.10 × 0.08 × 0.08

Data collection
Diffractometer	Bruker–Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (SORTAV; Blessing, 1995)
T_min, T_max	0.730, 0.771
No. of measured, independent and observed [I > 2σ(I)] reflections	11933, 2773, 2142
R_int	0.081
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.060, 0.166, 1.10
No. of reflections	2773
No. of parameters	149
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.53, −0.99

Computer programs: COLLECT (Nonius, 2000), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), WinGX (Farrugia, 1999) and CHEMDRAW Ultra (Cambridge Soft 2001).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O1ⁱ	0.84	2.03	2.472 (10)	112.5
O1—H1A···Br1ⁱⁱ	0.84	2.85	3.509 (5)	136.7
N2—H2···Br1ⁱⁱ	0.88	2.97	3.690 (4)	139.7

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

Acknowledgements

We thank the Ministry of Higher Education, Kingdom of Saudi Arabia, for financial support.

References

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