1-Mesitylmethyl-1Hbenzotriazole 3-oxide

Ravindran Durai Nayagam, B.; Jebas, S.R.; Shakina, J.; Murugesan., R.; Schollmeyer, D.

doi:10.1107/S1600536810004824

organic compounds

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ISSN: 2056-9890

Volume 66| Part 3| March 2010| Page o637

doi:10.1107/S1600536810004824

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1-Mesitylmethyl-1Hbenzotriazole 3-oxide

B. Ravindran Durai Nayagam,^a ^* Samuel Robinson Jebas,^b J. Shakina,^c R. Murugesan.^d and Dieter Schollmeyer ^e

^aDepartment of Chemistry, Popes College, Sawyerpuram 628251, Tamilnadu, India, ^bDepartment of Physics, Sethupathy Government Arts College, Ramanathapuram 623502, Tamilnadu, India, ^cDepartment of Chemistry, Sarah Tucker College, Tirunelveli 627007, Tamilnadu, India, ^dDepartment of Chemistry, T.D.M.N.S. College, T. Kallikulam, Tamilnadu, India, and ^eInstitut für Organische Chemie, Universität Mainz, Duesbergweg 10-14, 55099 Mainz, Germany
^*Correspondence e-mail: b_ravidurai@yahoo.com

(Received 26 January 2010; accepted 7 February 2010; online 13 February 2010)

In the title compound, C₁₆H₁₇N₃O, the benzotriazole ring forms a dihedral angle of 77.25 (6)° with the phenyl ring. The benzotriazole ring is essentially planar with a maximum deviation of 0.012 (19) Å. Weak intermolecular C—H⋯O hydrogen bonds form R₂²(10) motifs. The crystal packing is consolidated by π—π interactions with centroid–centroid distances of 3.5994 (12) Å together with very weak C—H⋯π interactions.

Related literature

For bond-length data, see: Allen et al. (1987 ). For graph-set analysis of hydrogen bonding, see: Bernstein et al. (1995 ).

Experimental

Crystal data

C₁₆H₁₇N₃O
M_r = 267.33
Monoclinic, P 2₁ /c
a = 8.6269 (19) Å
b = 7.3422 (4) Å
c = 21.890 (5) Å
β = 103.133 (11)°
V = 1350.2 (4) Å³
Z = 4
Cu Kα radiation
μ = 0.67 mm⁻¹
T = 193 K
0.35 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (CORINC; Draeger & Gattow (1971 ) T_min = 0.799, T_max = 0.936
2722 measured reflections
2545 independent reflections
2243 reflections with I > 2σ(I)
R_int = 0.091
3 standard reflections every 60 min intensity decay: 2%

Refinement

R[F² > 2σ(F²)] = 0.046
wR(F²) = 0.132
S = 1.09
2546 reflections
184 parameters
H-atom parameters constrained
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg3 is the centroid of the C12–C17 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯O10ⁱ	0.95	2.35	3.190 (2)	147
C16—H16⋯O10ⁱⁱ	0.95	2.58	3.506 (2)	165
C18—H18A⋯Cg3ⁱⁱⁱ	0.98	2.98	3.810 (18)	144
Symmetry codes: (i) -x+1, -y+1, -z; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); cell refinement: CAD-4 EXPRESS; data reduction: CORINC (Draeger & Gattow, 1971); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810004824/bt5182sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810004824/bt5182Isup2.hkl

checkCIF report

Comment top

The asymmetric unit of (I) comprises of one molecule of the title compound (Fig 1). The bond lengths and angles are found to have normal values (Allen et al., 1987). The benzotriazole ring is essentially planar with the maximum deviation from planarity being 0.012 (19) Å for atom C5. The mean plane of the benzotriazole ring (N1/N9/N8/C2—C7) forming a dihedral angle of 77.25 (6) Å with the mean plane of the phenyl ring (C12—C17). An intermolecular weak C—H···O hydrogen bonding generates a ring of motif R₂²(10) (Bernstein et al., 1995)

The crystal packing is stabilized by π—π stacking interactions [Cg1—Cg2ⁱ= of 3.5994 (12) Å; Cg1: (N1/N9/N8/C7/C2); Cg2:(C2—C): Symmetry code:(i) 1-X, –Y, –Z] together with weak C—H···π interactions.

Related literature top

For bond-length data, see: Allen et al. (1987). For graph-set analysis of hydrogen bonding, see: Bernstein et al. (1995).

Experimental top

A mixture of mono(bromomethyl)mesitylene (0.213 g, 1 mmol) and sodium salt of 1-Hydroxybenzotriazole (0.157,1 mmol) in ethanol (20 ml) was heated at 333 K with stirring for 30 min. The compound formed was filtered off, and dried. The compound was dissolved in ethanol and chloroform (1: 1v/v) and allowed to undergo slow evaporation. Colourless block shaped crystals were obtained after a week.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: CORINC (Draeger & Gattow, 1971); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme.

1-Mesitylmethyl-1Hbenzotriazole 3-oxide top

Crystal data top

C₁₆H₁₇N₃O	F(000) = 568
M_r = 267.33	D_x = 1.315 Mg m⁻³
Monoclinic, P2₁/c	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 8.6269 (19) Å	θ = 35–48°
b = 7.3422 (4) Å	µ = 0.67 mm⁻¹
c = 21.890 (5) Å	T = 193 K
β = 103.133 (11)°	Block, colourless
V = 1350.2 (4) Å³	0.35 × 0.20 × 0.10 mm
Z = 4

Data collection top

Enraf–Nonius CAD-4 diffractometer	2243 reflections with I > 2σ(I)
Radiation source: rotating anode	R_int = 0.091
Graphite monochromator	θ_max = 69.9°, θ_min = 4.2°
ω/2θ scans	h = 0→10
Absorption correction: ψ scan (CORINC; Draeger & Gattow (1971)	k = −8→0
T_min = 0.799, T_max = 0.936	l = −26→25
2722 measured reflections	3 standard reflections every 60 min
2545 independent reflections	intensity decay: 2%

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.132	H-atom parameters constrained
S = 1.09	w = 1/[σ²(F_o²) + (0.0705P)² + 0.4335P] where P = (F_o² + 2F_c²)/3
2546 reflections	(Δ/σ)_max < 0.001
184 parameters	Δρ_max = 0.23 e Å⁻³
0 restraints	Δρ_min = −0.26 e Å⁻³

Crystal data top

C₁₆H₁₇N₃O	V = 1350.2 (4) Å³
M_r = 267.33	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 8.6269 (19) Å	µ = 0.67 mm⁻¹
b = 7.3422 (4) Å	T = 193 K
c = 21.890 (5) Å	0.35 × 0.20 × 0.10 mm
β = 103.133 (11)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	2243 reflections with I > 2σ(I)
Absorption correction: ψ scan (CORINC; Draeger & Gattow (1971)	R_int = 0.091
T_min = 0.799, T_max = 0.936	3 standard reflections every 60 min
2722 measured reflections	intensity decay: 2%
2545 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.046	0 restraints
wR(F²) = 0.132	H-atom parameters constrained
S = 1.09	Δρ_max = 0.23 e Å⁻³
2546 reflections	Δρ_min = −0.26 e Å⁻³
184 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
N1	0.70466 (16)	−0.01341 (18)	0.11411 (6)	0.0277 (3)
C2	0.71052 (18)	0.0150 (2)	0.05338 (7)	0.0272 (3)
C3	0.7611 (2)	−0.0918 (2)	0.00798 (8)	0.0369 (4)
H3	0.7999	−0.2123	0.0167	0.044*
C4	0.7513 (2)	−0.0124 (3)	−0.04902 (8)	0.0411 (4)
H4	0.7846	−0.0801	−0.0808	0.049*
C5	0.6933 (2)	0.1673 (3)	−0.06290 (8)	0.0364 (4)
H5	0.6900	0.2166	−0.1033	0.044*
C6	0.64222 (18)	0.2710 (2)	−0.01957 (7)	0.0317 (4)
H6	0.6023	0.3909	−0.0286	0.038*
C7	0.65231 (17)	0.1899 (2)	0.03868 (7)	0.0262 (3)
N8	0.61389 (15)	0.25395 (18)	0.09300 (6)	0.0285 (3)
N9	0.64505 (16)	0.13267 (18)	0.13845 (6)	0.0294 (3)
O10	0.56088 (16)	0.41370 (17)	0.10077 (6)	0.0416 (3)
C11	0.7402 (2)	−0.1818 (2)	0.15108 (7)	0.0308 (4)
H11A	0.8203	−0.2529	0.1352	0.037*
H11B	0.6421	−0.2562	0.1450	0.037*
C12	0.80200 (18)	−0.1471 (2)	0.22014 (7)	0.0258 (3)
C13	0.96499 (17)	−0.1154 (2)	0.24416 (7)	0.0278 (3)
C14	1.01987 (18)	−0.0911 (2)	0.30840 (8)	0.0307 (4)
H14	1.1305	−0.0728	0.3249	0.037*
C15	0.9183 (2)	−0.0928 (2)	0.34912 (7)	0.0311 (4)
C16	0.75646 (19)	−0.1203 (2)	0.32423 (7)	0.0307 (4)
H16	0.6850	−0.1197	0.3515	0.037*
C17	0.69733 (18)	−0.1485 (2)	0.26051 (7)	0.0272 (3)
C18	1.0814 (2)	−0.1051 (2)	0.20228 (9)	0.0396 (4)
H18A	1.0922	−0.2256	0.1844	0.059*
H18B	1.1852	−0.0648	0.2269	0.059*
H18C	1.0424	−0.0181	0.1683	0.059*
C19	0.9812 (2)	−0.0637 (3)	0.41845 (8)	0.0460 (5)
H19A	0.9922	−0.1816	0.4400	0.069*
H19B	0.9070	0.0132	0.4348	0.069*
H19C	1.0853	−0.0039	0.4257	0.069*
C20	0.52065 (19)	−0.1764 (3)	0.23637 (8)	0.0393 (4)
H20A	0.4771	−0.0771	0.2076	0.059*
H20B	0.4684	−0.1772	0.2717	0.059*
H20C	0.5017	−0.2929	0.2141	0.059*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0360 (7)	0.0243 (7)	0.0232 (6)	0.0026 (5)	0.0075 (5)	0.0011 (5)
C2	0.0279 (7)	0.0279 (8)	0.0258 (7)	−0.0008 (6)	0.0060 (6)	−0.0003 (6)
C3	0.0467 (9)	0.0346 (9)	0.0297 (8)	0.0077 (7)	0.0096 (7)	−0.0025 (7)
C4	0.0477 (10)	0.0471 (11)	0.0304 (9)	0.0048 (8)	0.0131 (7)	−0.0050 (8)
C5	0.0394 (9)	0.0446 (10)	0.0249 (8)	−0.0020 (8)	0.0064 (7)	0.0047 (7)
C6	0.0304 (8)	0.0338 (9)	0.0290 (8)	0.0001 (6)	0.0028 (6)	0.0053 (7)
C7	0.0242 (7)	0.0283 (8)	0.0255 (7)	−0.0007 (6)	0.0042 (6)	−0.0001 (6)
N8	0.0315 (7)	0.0251 (7)	0.0284 (6)	0.0036 (5)	0.0060 (5)	0.0007 (5)
N9	0.0364 (7)	0.0255 (7)	0.0270 (6)	0.0032 (5)	0.0083 (5)	−0.0002 (5)
O10	0.0574 (8)	0.0284 (6)	0.0406 (7)	0.0164 (5)	0.0141 (6)	0.0016 (5)
C11	0.0442 (9)	0.0216 (8)	0.0261 (8)	0.0000 (6)	0.0070 (7)	0.0023 (6)
C12	0.0312 (8)	0.0195 (7)	0.0263 (7)	0.0013 (6)	0.0057 (6)	0.0023 (6)
C13	0.0304 (8)	0.0200 (7)	0.0344 (8)	0.0026 (6)	0.0099 (6)	0.0005 (6)
C14	0.0262 (7)	0.0231 (8)	0.0397 (9)	0.0012 (6)	0.0011 (6)	−0.0001 (6)
C15	0.0384 (8)	0.0250 (8)	0.0274 (8)	0.0030 (6)	0.0023 (6)	0.0019 (6)
C16	0.0349 (8)	0.0296 (8)	0.0295 (8)	0.0035 (6)	0.0112 (6)	0.0061 (6)
C17	0.0285 (7)	0.0250 (8)	0.0275 (8)	0.0003 (6)	0.0053 (6)	0.0065 (6)
C18	0.0378 (9)	0.0342 (9)	0.0523 (11)	−0.0014 (7)	0.0217 (8)	−0.0040 (8)
C19	0.0543 (11)	0.0473 (11)	0.0313 (9)	0.0008 (9)	−0.0006 (8)	−0.0014 (8)
C20	0.0290 (8)	0.0495 (11)	0.0383 (9)	−0.0042 (7)	0.0053 (7)	0.0096 (8)

Geometric parameters (Å, º) top

N1—N9	1.3502 (18)	C12—C13	1.404 (2)
N1—C2	1.358 (2)	C13—C14	1.390 (2)
N1—C11	1.4713 (19)	C13—C18	1.508 (2)
C2—C7	1.390 (2)	C14—C15	1.384 (2)
C2—C3	1.411 (2)	C14—H14	0.9500
C3—C4	1.362 (2)	C15—C16	1.393 (2)
C3—H3	0.9500	C15—C19	1.506 (2)
C4—C5	1.419 (3)	C16—C17	1.388 (2)
C4—H4	0.9500	C16—H16	0.9500
C5—C6	1.365 (2)	C17—C20	1.509 (2)
C5—H5	0.9500	C18—H18A	0.9800
C6—C7	1.392 (2)	C18—H18B	0.9800
C6—H6	0.9500	C18—H18C	0.9800
C7—N8	1.387 (2)	C19—H19A	0.9800
N8—O10	1.2842 (17)	C19—H19B	0.9800
N8—N9	1.3166 (18)	C19—H19C	0.9800
C11—C12	1.506 (2)	C20—H20A	0.9800
C11—H11A	0.9900	C20—H20B	0.9800
C11—H11B	0.9900	C20—H20C	0.9800
C12—C17	1.400 (2)

N9—N1—C2	111.49 (12)	C14—C13—C12	118.82 (14)
N9—N1—C11	120.06 (12)	C14—C13—C18	119.21 (14)
C2—N1—C11	128.19 (13)	C12—C13—C18	121.96 (15)
N1—C2—C7	106.08 (13)	C15—C14—C13	122.03 (14)
N1—C2—C3	133.66 (15)	C15—C14—H14	119.0
C7—C2—C3	120.26 (14)	C13—C14—H14	119.0
C4—C3—C2	116.27 (16)	C14—C15—C16	118.30 (14)
C4—C3—H3	121.9	C14—C15—C19	120.77 (15)
C2—C3—H3	121.9	C16—C15—C19	120.92 (15)
C3—C4—C5	122.64 (16)	C17—C16—C15	121.43 (14)
C3—C4—H4	118.7	C17—C16—H16	119.3
C5—C4—H4	118.7	C15—C16—H16	119.3
C6—C5—C4	121.56 (15)	C16—C17—C12	119.41 (14)
C6—C5—H5	119.2	C16—C17—C20	118.91 (14)
C4—C5—H5	119.2	C12—C17—C20	121.67 (14)
C5—C6—C7	115.80 (16)	C13—C18—H18A	109.5
C5—C6—H6	122.1	C13—C18—H18B	109.5
C7—C6—H6	122.1	H18A—C18—H18B	109.5
N8—C7—C2	105.00 (13)	C13—C18—H18C	109.5
N8—C7—C6	131.53 (15)	H18A—C18—H18C	109.5
C2—C7—C6	123.47 (15)	H18B—C18—H18C	109.5
O10—N8—N9	122.37 (13)	C15—C19—H19A	109.5
O10—N8—C7	125.79 (13)	C15—C19—H19B	109.5
N9—N8—C7	111.77 (13)	H19A—C19—H19B	109.5
N8—N9—N1	105.66 (12)	C15—C19—H19C	109.5
N1—C11—C12	113.08 (13)	H19A—C19—H19C	109.5
N1—C11—H11A	109.0	H19B—C19—H19C	109.5
C12—C11—H11A	109.0	C17—C20—H20A	109.5
N1—C11—H11B	109.0	C17—C20—H20B	109.5
C12—C11—H11B	109.0	H20A—C20—H20B	109.5
H11A—C11—H11B	107.8	C17—C20—H20C	109.5
C17—C12—C13	119.98 (14)	H20A—C20—H20C	109.5
C17—C12—C11	120.02 (14)	H20B—C20—H20C	109.5
C13—C12—C11	120.00 (14)

N9—N1—C2—C7	0.47 (17)	C11—N1—N9—N8	−174.86 (13)
C11—N1—C2—C7	174.51 (14)	N9—N1—C11—C12	−35.7 (2)
N9—N1—C2—C3	−179.86 (17)	C2—N1—C11—C12	150.74 (15)
C11—N1—C2—C3	−5.8 (3)	N1—C11—C12—C17	95.32 (17)
N1—C2—C3—C4	−178.70 (17)	N1—C11—C12—C13	−85.41 (18)
C7—C2—C3—C4	0.9 (2)	C17—C12—C13—C14	1.8 (2)
C2—C3—C4—C5	−0.2 (3)	C11—C12—C13—C14	−177.43 (13)
C3—C4—C5—C6	−0.6 (3)	C17—C12—C13—C18	−177.49 (14)
C4—C5—C6—C7	0.6 (2)	C11—C12—C13—C18	3.2 (2)
N1—C2—C7—N8	−0.46 (16)	C12—C13—C14—C15	−1.6 (2)
C3—C2—C7—N8	179.81 (14)	C18—C13—C14—C15	177.75 (14)
N1—C2—C7—C6	178.74 (14)	C13—C14—C15—C16	0.1 (2)
C3—C2—C7—C6	−1.0 (2)	C13—C14—C15—C19	−179.23 (15)
C5—C6—C7—N8	179.14 (15)	C14—C15—C16—C17	1.1 (2)
C5—C6—C7—C2	0.2 (2)	C19—C15—C16—C17	−179.53 (16)
C2—C7—N8—O10	177.40 (14)	C15—C16—C17—C12	−0.8 (2)
C6—C7—N8—O10	−1.7 (3)	C15—C16—C17—C20	−179.64 (15)
C2—C7—N8—N9	0.32 (17)	C13—C12—C17—C16	−0.7 (2)
C6—C7—N8—N9	−178.79 (15)	C11—C12—C17—C16	178.61 (14)
O10—N8—N9—N1	−177.24 (13)	C13—C12—C17—C20	178.11 (15)
C7—N8—N9—N1	−0.04 (17)	C11—C12—C17—C20	−2.6 (2)
C2—N1—N9—N8	−0.28 (17)

Hydrogen-bond geometry (Å, º) top

Cg3 is the centroid of the C12–C17 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O10ⁱ	0.95	2.35	3.190 (2)	147
C16—H16···O10ⁱⁱ	0.95	2.58	3.506 (2)	165
C18—H18A···Cg3ⁱⁱⁱ	0.98	2.98	3.810 (18)	144

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

Experimental details

Crystal data
Chemical formula	C₁₆H₁₇N₃O
M_r	267.33
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	193
a, b, c (Å)	8.6269 (19), 7.3422 (4), 21.890 (5)
β (°)	103.133 (11)
V (Å³)	1350.2 (4)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.67
Crystal size (mm)	0.35 × 0.20 × 0.10

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	ψ scan (CORINC; Draeger & Gattow (1971)
T_min, T_max	0.799, 0.936
No. of measured, independent and observed [I > 2σ(I)] reflections	2722, 2545, 2243
R_int	0.091
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.132, 1.09
No. of reflections	2546
No. of parameters	184
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.23, −0.26

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), CORINC (Draeger & Gattow, 1971), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg3 is the centroid of the C12–C17 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O10ⁱ	0.95	2.35	3.190 (2)	147.1
C16—H16···O10ⁱⁱ	0.95	2.58	3.506 (2)	164.8
C18—H18A···Cg3ⁱⁱⁱ	0.98	2.98	3.810 (18)	144

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

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem.Soc. Perkin Trans. 2, pp. S1–S19. CrossRef Web of Science 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
Draeger, M. & Gattow, G. (1971). Acta Chem. Scand. 25, 761–762. CAS Google Scholar
Enraf–Nonius (1994). CAD-4 EXPRESS. Enraf–Nonius, Delft, The Netherlands. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar

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Volume 66| Part 3| March 2010| Page o637

doi:10.1107/S1600536810004824

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