organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

tert-Butyl N-[(S)-1-hydrazine­carbonyl-2-hy­droxy­ethyl]carbamate

aInstituto de Tecnologia em Farmacos, Fundação Oswaldo Cruz (FIOCRUZ), FarManguinhos, Rua Sizenando Nabuco, 100, Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil, bInstituto de Tecnologia em Farmacos, Fundação Oswaldo Cruz (FIOCRUZ), FarManguinhos, Rua Sizenando Nabuco, 100, Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil, cCHEMSOL, 1 Harcourt Road, Aberdeen AB15 5NY, Scotland, dCentro de Desenvolvimento Tecnológico em Saúde (CDTS), Fundação Oswaldo Cruz (FIOCRUZ), Casa Amarela, Campus de Manguinhos, Av. Brasil 4365, 21040-900 Rio de Janeiro, RJ, Brazil, and eDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
*Correspondence e-mail: edward.tiekink@gmail.com

(Received 25 March 2010; accepted 25 March 2010; online 31 March 2010)

In the title compound, C8H17N3O4, the dihedral angle between the hydrazinecarbonyl and carbamate groups is 44.94 (12)°, and the carbonyl groups are anti to each other. In the crystal, the hydr­oxy group forms an O—H⋯Na (a = amine) hydrogen bond and each of the four N—H atoms forms an N—H⋯O hydrogen bond; the hydrazinecarbonyl O atom accepts two such bonds. This results in two-dimensional arrays in the ab plane, mediated by the hydrogen bonding, sandwiched by tert-butyl groups.

Related literature

For background to the use of serinyl compounds as potential anti-tuberculosis agents, see: Pinheiro et al. (2007[Pinheiro, A. C., Kaiser, C. R., Lourenço, M. C. S., de Souza, M. V. N., Wardell, S. M. S. V. & Wardell, J. L. (2007). J. Chem. Res. pp. 180-184.]).

[Scheme 1]

Experimental

Crystal data
  • C8H17N3O4

  • Mr = 219.25

  • Monoclinic, P 21

  • a = 6.9274 (5) Å

  • b = 5.0074 (4) Å

  • c = 16.2388 (15) Å

  • β = 94.483 (5)°

  • V = 561.57 (8) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 120 K

  • 0.26 × 0.14 × 0.03 mm

Data collection
  • Nonius KappaCCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2007[Sheldrick, G. M. (2007). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.616, Tmax = 0.746

  • 6687 measured reflections

  • 1428 independent reflections

  • 1168 reflections with I > 2σ(I)

  • Rint = 0.062

Refinement
  • R[F2 > 2σ(F2)] = 0.046

  • wR(F2) = 0.149

  • S = 1.23

  • 1428 reflections

  • 154 parameters

  • 6 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.30 e Å−3

  • Δρmin = −0.34 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O2—H1o⋯N1i 0.84 (3) 1.94 (3) 2.776 (4) 174 (5)
N1—H1n⋯O2i 0.91 (3) 2.24 (3) 3.121 (4) 162 (4)
N1—H2n⋯O1ii 0.91 (1) 2.29 (2) 3.070 (4) 144 (3)
N2—H3n⋯O1iii 0.88 (2) 2.18 (2) 2.985 (4) 152 (3)
N3—H4n⋯O3iv 0.88 (1) 2.02 (1) 2.892 (4) 172 (3)
Symmetry codes: (i) [-x, y+{\script{1\over 2}}, -z+1]; (ii) [-x+1, y-{\script{1\over 2}}, -z+1]; (iii) x, y-1, z; (iv) x, y+1, z.

Data collection: COLLECT (Hooft, 1998[Hooft, R. W. W. (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and DIAMOND (Brandenburg, 2006[Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). publCIF. In preparation.]).

Supporting information


Comment top

Continuing our interests in serinyl compounds as potential anti-tuberculosis agents (Pinheiro et al., 2007), we have prepared the title compound, tert-butyl N-[1(S)-1-(hydrazinecarbonyl)-2-hydroxyethyl]carbamate (I) from L-serine methyl ester hydrochloride, as a precursor of a series of tert-butyl N-(2-hydroxy-1-(S)-{N'-[(1E)-(2-aryl)methylidene]-hydrazinecarbonyl}ethyl)carbamates. We now report the syntheses and structure of (I).

The molecular structure of (I), Fig. 1, is twisted with the dihedral angle formed between the least-squares planes through the hydrazinecarbonyl (r.m.s. deviation = 0.0045 Å) and carbamate (r.m.s. deviation = 0.021 Å) residues being 44.94 (12) °. The carbonyl-O1 and O3 atoms lie to opposite sides of the molecule as seen in the pseudo O1–C1···C4–O3 torsion angle of -176.7 (3) °. Finally, each of the N–H groups is anti to the adjacent carbonyl so that the N–H groups, too, lie to opposite sides of the molecule. Although the absolute structure could not be determined experimentally, the assignment of the S-configuration at the C2 atom is based on the starting reagents. There are five acidic H atoms in the structure, and each of these forms a significant hydrogen bonding interaction, Table 1. The hydroxyl-O2–H forms an O–H···N bond with the amino-N1 atom. The carbonyl-O1 atom accepts two N–H hydrogen bonds, one from the amino-N1 atom and the other from the hydrazine-N2. The second amino-N1–H atom forms a hydrogen bond with the hydroxyl-O2 atom, and, finally, the carbamate-N3–H interacts with the O3-carbonyl atom. The hydrogen bonds cooperate with each other to form a 2-D array in the ab plane, Fig. 2, and these stack along the c axis being sandwiched by the t-butyl groups, Fig. 3.

Related literature top

For background to the use of serinyl compounds as potential anti-tuberculosis agents, see: Pinheiro et al. (2007).

Experimental top

To a stirred ethanol solution (10 ml) of methyl (2S)-2-[(tert-butoxycarbonyl)amino]-3-hydroxypropanoate (0.3 g, 1.37 mmol), obtained from L-serine methyl ester hydrochloride and (BOC)2O, at room temperature was added N2H4.H2O (80%, 5.5 mmol). The reaction mixture was stirred for 24 hours at room temperature and concentrated under reduced pressure. The residue was columned chromatographed on silica gel using a gradient of 0 to 5% chloroform in methanol, affording the title compound as a white solid in 70% yield. The crystals used in the structural study were grown from EtOH solution, m. pt. 403–404 K. 1H NMR (500 MHz, DMSO-d6) δ (ppm): 9.02 (1H, s, NHNH2), 6.58 (1H, d, J = 8.2, NHCH), 4.81 (1H, t, J = 5.6, OH), 4.19 (2H, s, NHNH2), 3.93 (1H, m, CH), 3.60–3.40 (2H, m, CH2OH), 1.37 (9H, s, (CH3)3C). 13C NMR (125 MHz, DMSO-d6) δ (ppm): 169.7 (COCH), 155.1 (COO), 78.1 ((CH3)3C), 61.9 (CH2OH), 55.5 (CH), 28.2 ((CH3)3C). IR (cm-1, KBr): 3281 (O—H), 1699 (COCH), 1668 (COO). EM/ESI (m/z [M—H]-): 218.1.

Refinement top

The C-bound H atoms were geometrically placed (C–H = 0.98–1.00 Å) and refined as riding with Uiso(H) = 1.2-1.5Ueq(parent atom). The O-bound H atom was refined with the distance restraint O–H = 0.840±0.001, and with Uiso(H) = 1.5Ueq(O). The N-bound H atoms were treated similarly with N–H = 0.880±0.001 and 0.910±0.001 Å, and with Uiso(H) = 1.2Ueq(N). In the absence of significant anomalous scattering effects, 1067 Friedel pairs were averaged in the final refinement.

Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); data reduction: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.
[Figure 2] Fig. 2. A view of a supramolecular array in (I) in the ab plane. The O–H···N and N–H···O hydrogen bonding interactions are shown as orange and blue dashed lines, respectively. Colour code: O, red; N, blue; C, grey; and H, green.
[Figure 3] Fig. 3. A view of the crystal packing in (I) in projection down the b axis, showing the stacking of layers. The O–H···N and N–H···O hydrogen bonding interactions are shown as orange and blue dashed lines, respectively. Colour code: O, red; N, blue; C, grey; and H, green.
tert-Butyl N-[(S)-1-hydrazinecarbonyl-2-hydroxyethyl]carbamate top
Crystal data top
C8H17N3O4F(000) = 236
Mr = 219.25Dx = 1.297 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 10838 reflections
a = 6.9274 (5) Åθ = 2.9–27.5°
b = 5.0074 (4) ŵ = 0.10 mm1
c = 16.2388 (15) ÅT = 120 K
β = 94.483 (5)°Plate, colourless
V = 561.57 (8) Å30.26 × 0.14 × 0.03 mm
Z = 2
Data collection top
Nonius KappaCCD
diffractometer
1428 independent reflections
Radiation source: Enraf–Nonius FR591 rotating anode1168 reflections with I > 2σ(I)
10 cm confocal mirrors monochromatorRint = 0.062
Detector resolution: 9.091 pixels mm-1θmax = 27.5°, θmin = 3.0°
ϕ and ω scansh = 88
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)
k = 66
Tmin = 0.616, Tmax = 0.746l = 2118
6687 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.149 w = 1/[σ2(Fo2) + (0.0838P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.23(Δ/σ)max = 0.001
1428 reflectionsΔρmax = 0.30 e Å3
154 parametersΔρmin = 0.34 e Å3
6 restraintsAbsolute structure: nd
Primary atom site location: structure-invariant direct methods
Crystal data top
C8H17N3O4V = 561.57 (8) Å3
Mr = 219.25Z = 2
Monoclinic, P21Mo Kα radiation
a = 6.9274 (5) ŵ = 0.10 mm1
b = 5.0074 (4) ÅT = 120 K
c = 16.2388 (15) Å0.26 × 0.14 × 0.03 mm
β = 94.483 (5)°
Data collection top
Nonius KappaCCD
diffractometer
1428 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)
1168 reflections with I > 2σ(I)
Tmin = 0.616, Tmax = 0.746Rint = 0.062
6687 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0466 restraints
wR(F2) = 0.149H atoms treated by a mixture of independent and constrained refinement
S = 1.23Δρmax = 0.30 e Å3
1428 reflectionsΔρmin = 0.34 e Å3
154 parametersAbsolute structure: nd
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
xyzUiso*/Ueq
O10.2906 (3)0.6236 (5)0.55336 (15)0.0226 (6)
O20.0983 (3)0.3069 (5)0.64307 (16)0.0245 (6)
H1O0.149 (6)0.452 (5)0.627 (3)0.037*
O30.4633 (4)0.1207 (6)0.74118 (17)0.0298 (7)
O40.6317 (3)0.2100 (5)0.81155 (14)0.0223 (6)
N10.2779 (4)0.2663 (6)0.42051 (18)0.0223 (7)
H1N0.205 (5)0.414 (5)0.409 (3)0.027*
H2N0.4053 (15)0.288 (9)0.412 (2)0.027*
N20.2663 (4)0.1984 (5)0.50498 (18)0.0198 (6)
H3N0.230 (5)0.033 (3)0.513 (2)0.024*
N30.4237 (4)0.3155 (5)0.70510 (18)0.0207 (6)
H4N0.429 (6)0.485 (2)0.720 (2)0.025*
C10.2715 (4)0.3813 (8)0.5650 (2)0.0181 (7)
C20.2480 (4)0.2659 (8)0.65093 (19)0.0182 (7)
H20.22670.06880.64600.022*
C30.0743 (2)0.3924 (5)0.68777 (11)0.0213 (7)
H3A0.07230.33980.74650.026*
H3B0.08420.58940.68520.026*
C40.5023 (2)0.1141 (5)0.75191 (11)0.0193 (7)
C50.7406 (2)0.0190 (5)0.86737 (11)0.0218 (7)
C60.8669 (2)0.2032 (5)0.92338 (11)0.0317 (9)
H6A0.95670.30010.89040.047*
H6B0.94060.09690.96570.047*
H6C0.78470.33100.95010.047*
C70.6005 (6)0.1336 (9)0.9179 (2)0.0300 (8)
H7A0.51090.00780.94110.045*
H7B0.67350.22910.96290.045*
H7C0.52720.26200.88230.045*
C80.8656 (5)0.1602 (7)0.8176 (2)0.0246 (8)
H8A0.78600.30460.79220.037*
H8B0.97050.23660.85420.037*
H8C0.92070.05490.77430.037*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0269 (12)0.0135 (13)0.0271 (14)0.0025 (11)0.0007 (10)0.0009 (10)
O20.0192 (12)0.0197 (14)0.0342 (14)0.0009 (10)0.0008 (10)0.0023 (11)
O30.0372 (13)0.0126 (13)0.0370 (15)0.0006 (12)0.0138 (11)0.0009 (11)
O40.0314 (12)0.0113 (12)0.0230 (12)0.0012 (10)0.0066 (10)0.0013 (10)
N10.0214 (14)0.0213 (17)0.0241 (15)0.0002 (12)0.0013 (12)0.0001 (13)
N20.0235 (14)0.0133 (13)0.0225 (15)0.0017 (12)0.0015 (11)0.0000 (13)
N30.0231 (13)0.0110 (14)0.0272 (15)0.0018 (12)0.0031 (12)0.0014 (13)
C10.0143 (13)0.0129 (16)0.0266 (18)0.0004 (13)0.0010 (12)0.0017 (15)
C20.0182 (15)0.0140 (17)0.0215 (17)0.0020 (13)0.0032 (13)0.0013 (13)
C30.0225 (15)0.0165 (16)0.0252 (17)0.0019 (15)0.0030 (13)0.0005 (14)
C40.0212 (15)0.0121 (17)0.0243 (18)0.0008 (14)0.0001 (13)0.0004 (13)
C50.0291 (18)0.0122 (16)0.0231 (18)0.0020 (15)0.0036 (14)0.0027 (14)
C60.042 (2)0.0165 (18)0.033 (2)0.0034 (17)0.0155 (17)0.0002 (17)
C70.0403 (19)0.022 (2)0.028 (2)0.0061 (18)0.0032 (16)0.0026 (16)
C80.0285 (16)0.0156 (19)0.0296 (19)0.0021 (15)0.0011 (14)0.0029 (15)
Geometric parameters (Å, º) top
O1—C11.236 (4)C2—H21.0000
O2—C31.416 (3)C3—H3A0.9900
O2—H1O0.84 (3)C3—H3B0.9900
O3—C41.216 (3)C5—C81.523 (4)
O4—C41.355 (3)C5—C61.523 (3)
O4—C51.482 (3)C5—C71.525 (4)
N1—N21.421 (4)C6—H6A0.9800
N1—H1N0.91 (3)C6—H6B0.9800
N1—H2N0.911 (13)C6—H6C0.9800
N2—C11.336 (5)C7—H7A0.9800
N2—H3N0.878 (18)C7—H7B0.9800
N3—C41.352 (3)C7—H7C0.9800
N3—C21.466 (4)C8—H8A0.9800
N3—H4N0.883 (14)C8—H8B0.9800
C1—C21.531 (5)C8—H8C0.9800
C2—C31.523 (4)
C3—O2—H1O102 (3)O3—C4—O4124.9 (2)
C4—O4—C5119.0 (2)N3—C4—O4110.6 (2)
N2—N1—H1N109 (3)O4—C5—C8109.80 (19)
N2—N1—H2N107 (2)O4—C5—C6102.46 (12)
H1N—N1—H2N114 (4)C8—C5—C6110.49 (15)
C1—N2—N1122.7 (3)O4—C5—C7109.8 (2)
C1—N2—H3N122 (3)C8—C5—C7113.7 (2)
N1—N2—H3N114 (3)C6—C5—C7109.99 (17)
C4—N3—C2119.3 (3)C5—C6—H6A109.5
C4—N3—H4N124 (3)C5—C6—H6B109.5
C2—N3—H4N110 (3)H6A—C6—H6B109.5
O1—C1—N2123.9 (3)C5—C6—H6C109.5
O1—C1—C2122.0 (3)H6A—C6—H6C109.5
N2—C1—C2114.0 (3)H6B—C6—H6C109.5
N3—C2—C3109.8 (2)C5—C7—H7A109.5
N3—C2—C1109.9 (3)C5—C7—H7B109.5
C3—C2—C1110.2 (2)H7A—C7—H7B109.5
N3—C2—H2109.0C5—C7—H7C109.5
C3—C2—H2109.0H7A—C7—H7C109.5
C1—C2—H2109.0H7B—C7—H7C109.5
O2—C3—C2109.54 (19)C5—C8—H8A109.5
O2—C3—H3A109.8C5—C8—H8B109.5
C2—C3—H3A109.8H8A—C8—H8B109.5
O2—C3—H3B109.8C5—C8—H8C109.5
C2—C3—H3B109.8H8A—C8—H8C109.5
H3A—C3—H3B108.2H8B—C8—H8C109.5
O3—C4—N3124.4 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H1o···N1i0.84 (3)1.94 (3)2.776 (4)174 (5)
N1—H1n···O2i0.91 (3)2.24 (3)3.121 (4)162 (4)
N1—H2n···O1ii0.91 (1)2.29 (2)3.070 (4)144 (3)
N2—H3n···O1iii0.88 (2)2.18 (2)2.985 (4)152 (3)
N3—H4n···O3iv0.88 (1)2.02 (1)2.892 (4)172 (3)
Symmetry codes: (i) x, y+1/2, z+1; (ii) x+1, y1/2, z+1; (iii) x, y1, z; (iv) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC8H17N3O4
Mr219.25
Crystal system, space groupMonoclinic, P21
Temperature (K)120
a, b, c (Å)6.9274 (5), 5.0074 (4), 16.2388 (15)
β (°) 94.483 (5)
V3)561.57 (8)
Z2
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.26 × 0.14 × 0.03
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2007)
Tmin, Tmax0.616, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
6687, 1428, 1168
Rint0.062
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.149, 1.23
No. of reflections1428
No. of parameters154
No. of restraints6
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.30, 0.34
Absolute structureNd

Computer programs: , DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H1o···N1i0.84 (3)1.94 (3)2.776 (4)174 (5)
N1—H1n···O2i0.91 (3)2.24 (3)3.121 (4)162 (4)
N1—H2n···O1ii0.911 (13)2.29 (2)3.070 (4)144 (3)
N2—H3n···O1iii0.878 (18)2.183 (18)2.985 (4)152 (3)
N3—H4n···O3iv0.883 (14)2.015 (12)2.892 (4)172 (3)
Symmetry codes: (i) x, y+1/2, z+1; (ii) x+1, y1/2, z+1; (iii) x, y1, z; (iv) x, y+1, z.
 

Footnotes

Additional correspondence author, e-mail: j.wardell@abdn.ac.uk.

Acknowledgements

The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES and FAPEMIG (Brazil).

References

First citationBrandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationHooft, R. W. W. (1998). COLLECT. Nonius BV, Delft, The Netherlands.  Google Scholar
First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.  Google Scholar
First citationPinheiro, A. C., Kaiser, C. R., Lourenço, M. C. S., de Souza, M. V. N., Wardell, S. M. S. V. & Wardell, J. L. (2007). J. Chem. Res. pp. 180–184.  CrossRef Google Scholar
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