rac-5-Acetyl-6-hy­droxy-3,6-dimethyl-4-phenyl-4,5,6,7-tetra­hydro-2H-indazole

Maharramov, A.M.; Ismiyev, A.I.; Rashidov, B.A.; Aliyev, I.V.

doi:10.1107/S1600536811013195

organic compounds

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ISSN: 2056-9890

Volume 67| Part 5| May 2011| Page o1127

doi:10.1107/S1600536811013195

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rac-5-Acetyl-6-hydroxy-3,6-dimethyl-4-phenyl-4,5,6,7-tetrahydro-2H-indazole

Abel M. Maharramov,^a ^* Arif I. Ismiyev,^a Bahruz A. Rashidov ^a and Ilkin V. Aliyev ^a

^aBaku State University, Z. Khalilov St 23, Baku, AZ-1148, Azerbaijan
^*Correspondence e-mail: orglab@mail.ru

(Received 5 April 2011; accepted 8 April 2011; online 13 April 2011)

The title compound, C₁₇H₂₀N₂O₂, is chiral but crystallizes in a centrosymmetric space group as a racemate, the relative configuration at the stereogenic centres being 2S*,3R*,4S*. The cyclohexane ring adopts a half-chair conformation while the pyrazole ring has an envelope conformation. The crystal packing displays intermolecular O—H⋯N and N—H⋯O hydrogen bonding.

Related literature

For background to the use of β-cycloketols as synthons in syntheses of pyrazoles, see: Pramula et al. (1985 ).

Experimental

Crystal data

C₁₇H₂₀N₂O₂
M_r = 284.35
Monoclinic, C 2/c
a = 18.6999 (9) Å
b = 5.6415 (3) Å
c = 28.4855 (14) Å
β = 94.498 (1)°
V = 2995.8 (3) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.30 × 0.30 × 0.20 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ) T_min = 0.975, T_max = 0.984
16597 measured reflections
3709 independent reflections
3079 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.045
wR(F²) = 0.129
S = 1.00
3709 reflections
193 parameters
H-atom parameters constrained
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯N1ⁱ	0.82	2.03	2.8487 (14)	178
N2—H2C⋯O1ⁱⁱ	0.86	2.11	2.9587 (15)	168
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ .

Data collection: APEX2 (Bruker, 2005 ); cell refinement: SAINT-Plus, (Bruker, 2001 ); data reduction: SAINT-Plus; 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: SHELXL97.

Supporting information

Crystal structure: contains datablocks Global, I. DOI: 10.1107/S1600536811013195/kp2321sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811013195/kp2321Isup2.hkl

checkCIF report

Comment top

The exploitation of a simple molecule with different functionalities for the synthesis of heterocycles is usefula approach. In fact, the β-cycloketols has been used as an effective synthon in some projected syntheses of pyrazoles (Pramula et al. 1985).

In the title compound, C₁₇H₂₀N₂O₂ (I), the cyclohexane ring adopts a half-chair conformation (Fig. 1). Cyclohexane ring has a chair conformation. The phenyl ring is in a pseudo-equatorial position. The torsion angle between the acetyl group and the phenyl substituent (C7—C2—C3—C13) is 64.88 (13) °indicating the pseudo-axial location of hydrogen atoms at C2 and C3. The crystal of (I) is racemate and consists of enantiomeric pairs where the relative configuration of the centres are 2S*,3R*,4S*. The crystal structure involves N—H···O and O—H···N intermolecular hydrogen bonds (Table 1 and Fig. 2).

Related literature top

For background to the use of β-cycloketols as synthons in syntheses of pyrazoles, see: Pramula et al. (1985).

Experimental top

2,4-Diacetyl-5-hydroxy-5-metyl-3-phenilcyclohexanon (20 mmol), hydrazine hydrate (20 mmol) were dissolved in 20 mL ethanol. The mixture was stirred at 345–350 K for 10 h. After cooling to room temperature, white crystals were obtained. The crystals were filtered off and washed with ethanol. Then, they were dissolved in ethanol (50 mL) and recrystallised to yield colourless block-shaped crystals suitable for data collection.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus, (Bruker, 2001); data reduction: SAINT-Plus, (Bruker, 2001); 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: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
	Fig. 2. Crystal packing of (I) with hydrogen bonding (dashed lines). H atoms not involved in hydrogen bonding have been omitted for clarity.

rac-5-Acetyl-6-hydroxy-3,6-dimethyl-4-phenyl-4,5,6,7- tetrahydro-2H-indazole top

Crystal data top

C₁₇H₂₀N₂O₂	F(000) = 1216
M_r = 284.35	D_x = 1.261 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 6277 reflections
a = 18.6999 (9) Å	θ = 2.5–28.2°
b = 5.6415 (3) Å	µ = 0.08 mm⁻¹
c = 28.4855 (14) Å	T = 296 K
β = 94.498 (1)°	Prism, colorless
V = 2995.8 (3) Å³	0.30 × 0.30 × 0.20 mm
Z = 8

Data collection top

Bruker APEXII CCD area-detector diffractometer	3709 independent reflections
Radiation source: fine-focus sealed tube	3079 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
phi and ω scans	θ_max = 28.3°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −24→24
T_min = 0.975, T_max = 0.984	k = −7→7
16597 measured reflections	l = −38→37

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)] = 0.045	Hydrogen site location: difference Fourier map
wR(F²) = 0.129	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.0701P)² + 1.7992P] where P = (F_o² + 2F_c²)/3
3709 reflections	(Δ/σ)_max = 0.001
193 parameters	Δρ_max = 0.32 e Å⁻³
0 restraints	Δρ_min = −0.16 e Å⁻³

Crystal data top

C₁₇H₂₀N₂O₂	V = 2995.8 (3) Å³
M_r = 284.35	Z = 8
Monoclinic, C2/c	Mo Kα radiation
a = 18.6999 (9) Å	µ = 0.08 mm⁻¹
b = 5.6415 (3) Å	T = 296 K
c = 28.4855 (14) Å	0.30 × 0.30 × 0.20 mm
β = 94.498 (1)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	3709 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	3079 reflections with I > 2σ(I)
T_min = 0.975, T_max = 0.984	R_int = 0.021
16597 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	0 restraints
wR(F²) = 0.129	H-atom parameters constrained
S = 1.00	Δρ_max = 0.32 e Å⁻³
3709 reflections	Δρ_min = −0.16 e Å⁻³
193 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
O1	0.76048 (5)	0.7902 (2)	0.61991 (4)	0.0481 (3)
O2	0.62374 (5)	0.43848 (16)	0.52715 (3)	0.0372 (2)
H2A	0.6097	0.4443	0.4992	0.056*
N1	0.42526 (6)	0.5528 (2)	0.57008 (4)	0.0369 (3)
N2	0.41169 (6)	0.3900 (2)	0.60311 (4)	0.0390 (3)
H2C	0.3693	0.3393	0.6074	0.047*
C1	0.47121 (7)	0.3149 (3)	0.62867 (5)	0.0347 (3)
C1A	0.52770 (6)	0.4380 (2)	0.61152 (4)	0.0291 (3)
C2	0.60733 (6)	0.4279 (2)	0.62496 (4)	0.0273 (2)
H2B	0.6259	0.2787	0.6132	0.033*
C3	0.64412 (6)	0.6363 (2)	0.60052 (4)	0.0266 (2)
H3A	0.6312	0.7817	0.6167	0.032*
C4	0.61636 (6)	0.6655 (2)	0.54788 (4)	0.0284 (2)
C5	0.53694 (7)	0.7403 (2)	0.54570 (5)	0.0335 (3)
H5A	0.5334	0.9023	0.5567	0.040*
H5B	0.5164	0.7336	0.5134	0.040*
C5A	0.49626 (6)	0.5808 (2)	0.57540 (4)	0.0313 (3)
C6	0.46830 (8)	0.1288 (3)	0.66523 (6)	0.0514 (4)
H6A	0.4196	0.1082	0.6729	0.077*
H6B	0.4975	0.1754	0.6929	0.077*
H6C	0.4859	−0.0178	0.6535	0.077*
C7	0.62509 (6)	0.4376 (2)	0.67804 (4)	0.0309 (3)
C8	0.59834 (10)	0.6182 (3)	0.70426 (5)	0.0516 (4)
H8A	0.5690	0.7324	0.6892	0.062*
C9	0.61420 (11)	0.6334 (4)	0.75247 (6)	0.0605 (5)
H9A	0.5956	0.7568	0.7694	0.073*
C10	0.65747 (10)	0.4662 (4)	0.77516 (5)	0.0561 (4)
H10A	0.6686	0.4763	0.8075	0.067*
C11	0.68412 (9)	0.2846 (4)	0.74998 (6)	0.0565 (4)
H11A	0.7131	0.1701	0.7653	0.068*
C12	0.66811 (8)	0.2700 (3)	0.70155 (5)	0.0422 (3)
H12A	0.6866	0.1457	0.6848	0.051*
C13	0.72575 (6)	0.6185 (2)	0.60593 (4)	0.0324 (3)
C14	0.76231 (8)	0.3969 (3)	0.59270 (7)	0.0492 (4)
H14A	0.8133	0.4200	0.5960	0.074*
H14B	0.7476	0.3575	0.5606	0.074*
H14C	0.7496	0.2701	0.6129	0.074*
C15	0.65806 (8)	0.8528 (3)	0.52295 (5)	0.0392 (3)
H15A	0.6384	0.8680	0.4909	0.059*
H15B	0.7075	0.8065	0.5234	0.059*
H15C	0.6546	1.0021	0.5388	0.059*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0303 (5)	0.0525 (6)	0.0605 (7)	−0.0132 (4)	−0.0030 (4)	−0.0091 (5)
O2	0.0473 (5)	0.0326 (5)	0.0306 (4)	0.0027 (4)	−0.0034 (4)	−0.0043 (4)
N1	0.0252 (5)	0.0509 (7)	0.0342 (5)	−0.0004 (5)	−0.0011 (4)	0.0027 (5)
N2	0.0234 (5)	0.0517 (7)	0.0418 (6)	−0.0053 (5)	0.0024 (4)	0.0039 (5)
C1	0.0266 (6)	0.0406 (7)	0.0372 (6)	−0.0024 (5)	0.0034 (5)	0.0025 (5)
C1A	0.0241 (5)	0.0327 (6)	0.0301 (6)	−0.0016 (4)	0.0005 (4)	0.0015 (5)
C2	0.0237 (5)	0.0292 (6)	0.0286 (5)	0.0000 (4)	−0.0005 (4)	0.0015 (4)
C3	0.0220 (5)	0.0275 (5)	0.0299 (5)	−0.0015 (4)	0.0004 (4)	−0.0016 (4)
C4	0.0277 (5)	0.0289 (6)	0.0284 (5)	−0.0011 (4)	0.0008 (4)	0.0005 (4)
C5	0.0293 (6)	0.0365 (6)	0.0338 (6)	0.0014 (5)	−0.0019 (5)	0.0066 (5)
C5A	0.0256 (6)	0.0375 (6)	0.0302 (6)	−0.0003 (5)	−0.0009 (4)	0.0005 (5)
C6	0.0388 (8)	0.0555 (9)	0.0611 (10)	−0.0003 (7)	0.0110 (7)	0.0223 (8)
C7	0.0254 (5)	0.0364 (6)	0.0305 (6)	−0.0010 (5)	−0.0006 (4)	0.0036 (5)
C8	0.0628 (10)	0.0550 (9)	0.0363 (7)	0.0217 (8)	−0.0006 (7)	−0.0010 (7)
C9	0.0754 (12)	0.0694 (12)	0.0368 (8)	0.0071 (10)	0.0062 (8)	−0.0096 (8)
C10	0.0557 (9)	0.0811 (13)	0.0306 (7)	−0.0116 (9)	−0.0017 (6)	0.0079 (8)
C11	0.0501 (9)	0.0747 (12)	0.0429 (8)	0.0074 (8)	−0.0067 (7)	0.0210 (8)
C12	0.0390 (7)	0.0463 (8)	0.0406 (7)	0.0067 (6)	0.0000 (6)	0.0088 (6)
C13	0.0245 (5)	0.0397 (7)	0.0326 (6)	−0.0046 (5)	0.0002 (4)	0.0021 (5)
C14	0.0283 (6)	0.0477 (8)	0.0723 (10)	0.0031 (6)	0.0074 (6)	−0.0021 (8)
C15	0.0376 (7)	0.0406 (7)	0.0402 (7)	−0.0055 (6)	0.0076 (5)	0.0066 (6)

Geometric parameters (Å, º) top

O1—C13	1.2157 (17)	C6—H6A	0.9600
O2—C4	1.4215 (15)	C6—H6B	0.9600
O2—H2A	0.8200	C6—H6C	0.9600
N1—C5A	1.3338 (16)	C7—C8	1.380 (2)
N1—N2	1.3529 (16)	C7—C12	1.3803 (18)
N2—C1	1.3496 (17)	C8—C9	1.385 (2)
N2—H2C	0.8600	C8—H8A	0.9300
C1—C1A	1.3847 (17)	C9—C10	1.371 (3)
C1—C6	1.483 (2)	C9—H9A	0.9300
C1A—C5A	1.3996 (17)	C10—C11	1.367 (3)
C1A—C2	1.5093 (16)	C10—H10A	0.9300
C2—C7	1.5235 (16)	C11—C12	1.391 (2)
C2—C3	1.5543 (16)	C11—H11A	0.9300
C2—H2B	0.9800	C12—H12A	0.9300
C3—C13	1.5256 (16)	C13—C14	1.488 (2)
C3—C4	1.5566 (16)	C14—H14A	0.9600
C3—H3A	0.9800	C14—H14B	0.9600
C4—C15	1.5218 (17)	C14—H14C	0.9600
C4—C5	1.5405 (17)	C15—H15A	0.9600
C5—C5A	1.4847 (18)	C15—H15B	0.9600
C5—H5A	0.9700	C15—H15C	0.9600
C5—H5B	0.9700

C4—O2—H2A	109.5	C1—C6—H6B	109.5
C5A—N1—N2	103.94 (10)	H6A—C6—H6B	109.5
C1—N2—N1	113.36 (11)	C1—C6—H6C	109.5
C1—N2—H2C	123.3	H6A—C6—H6C	109.5
N1—N2—H2C	123.3	H6B—C6—H6C	109.5
N2—C1—C1A	105.78 (12)	C8—C7—C12	117.74 (12)
N2—C1—C6	121.79 (12)	C8—C7—C2	120.25 (11)
C1A—C1—C6	132.37 (12)	C12—C7—C2	122.01 (12)
C1—C1A—C5A	105.07 (11)	C7—C8—C9	121.61 (15)
C1—C1A—C2	131.02 (11)	C7—C8—H8A	119.2
C5A—C1A—C2	123.88 (11)	C9—C8—H8A	119.2
C1A—C2—C7	112.60 (10)	C10—C9—C8	119.82 (17)
C1A—C2—C3	108.68 (9)	C10—C9—H9A	120.1
C7—C2—C3	110.35 (9)	C8—C9—H9A	120.1
C1A—C2—H2B	108.4	C11—C10—C9	119.62 (15)
C7—C2—H2B	108.4	C11—C10—H10A	120.2
C3—C2—H2B	108.4	C9—C10—H10A	120.2
C13—C3—C2	112.29 (10)	C10—C11—C12	120.39 (15)
C13—C3—C4	111.09 (9)	C10—C11—H11A	119.8
C2—C3—C4	112.68 (9)	C12—C11—H11A	119.8
C13—C3—H3A	106.8	C7—C12—C11	120.82 (15)
C2—C3—H3A	106.8	C7—C12—H12A	119.6
C4—C3—H3A	106.8	C11—C12—H12A	119.6
O2—C4—C15	111.21 (10)	O1—C13—C14	120.56 (12)
O2—C4—C5	110.78 (10)	O1—C13—C3	119.02 (12)
C15—C4—C5	108.59 (10)	C14—C13—C3	120.39 (11)
O2—C4—C3	105.60 (9)	C13—C14—H14A	109.5
C15—C4—C3	112.25 (10)	C13—C14—H14B	109.5
C5—C4—C3	108.38 (9)	H14A—C14—H14B	109.5
C5A—C5—C4	110.28 (10)	C13—C14—H14C	109.5
C5A—C5—H5A	109.6	H14A—C14—H14C	109.5
C4—C5—H5A	109.6	H14B—C14—H14C	109.5
C5A—C5—H5B	109.6	C4—C15—H15A	109.5
C4—C5—H5B	109.6	C4—C15—H15B	109.5
H5A—C5—H5B	108.1	H15A—C15—H15B	109.5
N1—C5A—C1A	111.85 (11)	C4—C15—H15C	109.5
N1—C5A—C5	123.86 (11)	H15A—C15—H15C	109.5
C1A—C5A—C5	124.28 (11)	H15B—C15—H15C	109.5
C1—C6—H6A	109.5

C5A—N1—N2—C1	−0.17 (16)	N2—N1—C5A—C1A	−0.17 (15)
N1—N2—C1—C1A	0.43 (16)	N2—N1—C5A—C5	178.45 (12)
N1—N2—C1—C6	−177.22 (13)	C1—C1A—C5A—N1	0.43 (15)
N2—C1—C1A—C5A	−0.50 (15)	C2—C1A—C5A—N1	178.64 (11)
C6—C1—C1A—C5A	176.80 (16)	C1—C1A—C5A—C5	−178.19 (12)
N2—C1—C1A—C2	−178.53 (13)	C2—C1A—C5A—C5	0.0 (2)
C6—C1—C1A—C2	−1.2 (3)	C4—C5—C5A—N1	−158.94 (12)
C1—C1A—C2—C7	−47.39 (18)	C4—C5—C5A—C1A	19.52 (18)
C5A—C1A—C2—C7	134.90 (13)	C1A—C2—C7—C8	−53.32 (17)
C1—C1A—C2—C3	−169.96 (13)	C3—C2—C7—C8	68.31 (16)
C5A—C1A—C2—C3	12.33 (16)	C1A—C2—C7—C12	127.01 (13)
C1A—C2—C3—C13	−171.20 (10)	C3—C2—C7—C12	−111.37 (13)
C7—C2—C3—C13	64.88 (13)	C12—C7—C8—C9	0.5 (3)
C1A—C2—C3—C4	−44.84 (13)	C2—C7—C8—C9	−179.23 (16)
C7—C2—C3—C4	−168.76 (9)	C7—C8—C9—C10	0.0 (3)
C13—C3—C4—O2	74.30 (12)	C8—C9—C10—C11	−0.5 (3)
C2—C3—C4—O2	−52.70 (12)	C9—C10—C11—C12	0.6 (3)
C13—C3—C4—C15	−47.03 (14)	C8—C7—C12—C11	−0.4 (2)
C2—C3—C4—C15	−174.04 (10)	C2—C7—C12—C11	179.28 (13)
C13—C3—C4—C5	−166.96 (10)	C10—C11—C12—C7	−0.1 (3)
C2—C3—C4—C5	66.04 (12)	C2—C3—C13—O1	−129.62 (13)
O2—C4—C5—C5A	65.66 (13)	C4—C3—C13—O1	103.16 (14)
C15—C4—C5—C5A	−171.94 (11)	C2—C3—C13—C14	52.50 (16)
C3—C4—C5—C5A	−49.75 (13)	C4—C3—C13—C14	−74.72 (15)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···N1ⁱ	0.82	2.03	2.8487 (14)	178
N2—H2C···O1ⁱⁱ	0.86	2.11	2.9587 (15)	168

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

Experimental details

Crystal data
Chemical formula	C₁₇H₂₀N₂O₂
M_r	284.35
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	296
a, b, c (Å)	18.6999 (9), 5.6415 (3), 28.4855 (14)
β (°)	94.498 (1)
V (Å³)	2995.8 (3)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.30 × 0.30 × 0.20

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.975, 0.984
No. of measured, independent and observed [I > 2σ(I)] reflections	16597, 3709, 3079
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.668

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.129, 1.00
No. of reflections	3709
No. of parameters	193
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.16

Computer programs: APEX2 (Bruker, 2005), SAINT-Plus, (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···N1ⁱ	0.82	2.03	2.8487 (14)	178
N2—H2C···O1ⁱⁱ	0.86	2.11	2.9587 (15)	168

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

Acknowledgements

We thank Professor Victor N. Khrustalev for fruitful discussions and help in this work.

References

Bruker (2001). SAINT-Plus and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2005). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Pramula, B., Rajanarender, E., Shoolery, J. N. & Krishna, M. (1985). Ind. J. Chem. Sect. B, 24, 1255–1258. Google Scholar
Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar