3-Phenyl-1-(p-tol­yl)-1H-benzo[f]chromene benzene hemisolvate

Xue, M.W.

doi:10.1107/S1600536811001668

organic compounds

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Volume 67| Part 7| July 2011| Page o1668

doi:10.1107/S1600536811001668

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3-Phenyl-1-(p-tolyl)-1H-benzo[f]chromene benzene hemisolvate

Meng Wei Xue ^a ^*

^aBiochemical and Environmental Engineering College, Nanjing Xiaozhuang University, Nanjing 210017, People's Republic of China
^*Correspondence e-mail: xmw1102@sina.com

(Received 29 December 2010; accepted 11 January 2011; online 18 June 2011)

The title compound, C₂₆H₂₀O·0.5C₆H₆, was obtained from condensation reaction of 2-naphthol, 4-methylbenzaldehyde and phenylmethanamine. The naphthyl ring system is orented at dihedral angles of 84.11 (1) and 19.33 (8)° with respect to the mean planes of the two benzene rings.

Related literature

For applications of Betti-type reactions, see: Wang et al. (2005 ). The reaction of substituted phenols and aldehydes under controlled conditions has been used to build up a compound with two chiral centers, see: Gardiner & Raston (1997 ); Gutsche & Nam (1998 ). For bond-length data, see: Allen et al. (1987 ).

Experimental

Crystal data

C₂₆H₂₀O·0.5C₆H₆
M_r = 387.47
Monoclinic, P 2₁ /c
a = 12.653 (3) Å
b = 5.9049 (12) Å
c = 29.974 (8) Å
β = 109.08 (3)°
V = 2116.5 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 293 K
0.20 × 0.20 × 0.20 mm

Data collection

Rigaku Mercury2 diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ) T_min = 0.813, T_max = 1.000
14405 measured reflections
3623 independent reflections
1438 reflections with I > 2σ(I)
R_int = 0.148

Refinement

R[F² > 2σ(F²)] = 0.080
wR(F²) = 0.144
S = 0.93
3623 reflections
273 parameters
H-atom parameters constrained
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811001668/jh2252sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811001668/jh2252Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811001668/jh2252Isup3.cml

checkCIF report

Comment top

The reaction of substituted phenols and aldehydes under controlled conditions has been used to build up supramolecular compounds, the most important ones being calixarenes (Gardiner & Raston et al. 1997, Gutsche & Nam et al. 1998). 2-Naphthol reacts with aromatic aldehydes to produce 14-aryl-14H-dibenzo[a,j]xanthenes, which could be used as anti-inflamatory agents. Here we report the synthesis and crystal structure of the title compound. The asymmetric unit of the compound contains a benzene solvent molecule (Fig. 1). The bond lengths and angles are within normal ranges (Allen et al. 1987).

Rings of the two benzenes and naphthol are, of course, planar. The dihedral angles between rings A (C1–C10) and B (C12–C17), and between rings A and C (C21–C26), are 84.11 (1) and 19.33 (8), respectively. The orientation of ring B with respect to the mean planes of the two groups containing rings A and C, may be described by the dihedral angles of 84.11 (1) and 76.82 (2), respectively. The molecules are stabilized by intramolecular C—H···O hydrogen bonding (Table 1). Intermolecular attractions are only on the order of Van der Waals forces.

Related literature top

For applications of Betti-type reactions, see: Wang et al. (2005). For the reaction of substituted phenols and aldehydes under controlled conditions to form calixerenes, see: Gardiner & Raston (1997); Gutsche & Nam (1998). For bond-length data, see: Allen et al. (1987).

Experimental top

4-Methylbenzaldehyde (1.8 g, 0.015 mol) and phenylmethanamine (1.605 g, 0.015 mol) was added to 2-naphthol (2.16 g, 0.015 mol) without solvent under nitrogen. The temperature was raised to 120°C in one hour gradually and the mixture was stirred at this temperature for 12 h. The system was treated with 30 ml of ethanol 95% and cooled. The precipitate was filtered and washed with a small amount of ethanol 95%. The title compound was isolated using column chromatography (Petroleum ether: ethyl acetate-4:1). Single crystals suitable for X-ray diffraction analysis were obtained from slow evaporation of a solution of the title compound in b enzeneat room temperature.

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); 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).

Figures top

Fig. 1. Perspective structure of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

3-Phenyl-1-(p-tolyl)-1H-benzo[f]chromene benzene hemisolvate top

Crystal data top

C₂₆H₂₀O·0.5C₆H₆	F(000) = 820
M_r = 387.47	D_x = 1.216 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3623 reflections
a = 12.653 (3) Å	θ = 2.6–24.8°
b = 5.9049 (12) Å	µ = 0.07 mm⁻¹
c = 29.974 (8) Å	T = 293 K
β = 109.08 (3)°	Prism, colorless
V = 2116.5 (9) Å³	0.20 × 0.20 × 0.20 mm
Z = 4

Data collection top

Rigaku Mercury2 diffractometer	3623 independent reflections
Radiation source: fine-focus sealed tube	1438 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.148
Detector resolution: 13.6612 pixels mm^-1	θ_max = 24.8°, θ_min = 3.2°
CCD_Profile_fitting scans	h = −14→13
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −6→6
T_min = 0.813, T_max = 1.000	l = −35→35
14405 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)] = 0.080	H-atom parameters constrained
wR(F²) = 0.144	w = 1/[σ²(F_o²) + (0.010P)² + 1.9P] where P = (F_o² + 2F_c²)/3
S = 0.93	(Δ/σ)_max < 0.001
3623 reflections	Δρ_max = 0.18 e Å⁻³
273 parameters	Δρ_min = −0.20 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: 0.0054 (6)

Crystal data top

C₂₆H₂₀O·0.5C₆H₆	V = 2116.5 (9) Å³
M_r = 387.47	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 12.653 (3) Å	µ = 0.07 mm⁻¹
b = 5.9049 (12) Å	T = 293 K
c = 29.974 (8) Å	0.20 × 0.20 × 0.20 mm
β = 109.08 (3)°

Data collection top

Rigaku Mercury2 diffractometer	3623 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	1438 reflections with I > 2σ(I)
T_min = 0.813, T_max = 1.000	R_int = 0.148
14405 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.080	0 restraints
wR(F²) = 0.144	H-atom parameters constrained
S = 0.93	Δρ_max = 0.18 e Å⁻³
3623 reflections	Δρ_min = −0.20 e Å⁻³
273 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	0.1992 (2)	1.0645 (5)	0.23039 (9)	0.0549 (8)
C5	−0.1441 (4)	1.0682 (8)	0.16184 (15)	0.0502 (12)
C10	−0.0792 (4)	0.8897 (8)	0.15186 (14)	0.0464 (12)
C1	0.0391 (4)	0.8852 (7)	0.17364 (14)	0.0433 (11)
C11	0.1128 (3)	0.7117 (7)	0.16231 (13)	0.0464 (12)
H11A	0.0762	0.5639	0.1601	0.056*
C12	0.1302 (3)	0.7595 (8)	0.11524 (14)	0.0452 (11)
C2	0.0853 (4)	1.0539 (8)	0.20516 (14)	0.0468 (12)
C9	−0.1366 (4)	0.7168 (8)	0.12064 (15)	0.0591 (13)
H9A	−0.0957	0.5997	0.1135	0.071*
C3	0.0233 (4)	1.2317 (7)	0.21550 (14)	0.0497 (12)
H3A	0.0589	1.3428	0.2372	0.060*
C6	−0.2621 (4)	1.0666 (9)	0.13957 (16)	0.0664 (15)
H6A	−0.3047	1.1837	0.1455	0.080*
C4	−0.0887 (4)	1.2401 (8)	0.19354 (14)	0.0557 (13)
H4A	−0.1296	1.3606	0.1994	0.067*
C8	−0.2511 (5)	0.7169 (9)	0.10062 (16)	0.0689 (15)
H8A	−0.2870	0.5981	0.0811	0.083*
C13	0.1067 (4)	0.6008 (8)	0.08004 (16)	0.0673 (15)
H13A	0.0820	0.4582	0.0854	0.081*
C17	0.1694 (4)	0.9652 (8)	0.10589 (16)	0.0619 (14)
H17A	0.1881	1.0752	0.1294	0.074*
C15	0.1555 (4)	0.8569 (10)	0.02733 (16)	0.0649 (15)
C7	−0.3138 (4)	0.8968 (10)	0.10966 (17)	0.0737 (16)
H7A	−0.3910	0.9000	0.0952	0.088*
C14	0.1188 (4)	0.6477 (10)	0.03650 (17)	0.0752 (16)
H14A	0.1020	0.5365	0.0133	0.090*
C18	0.1597 (4)	0.9155 (10)	−0.02193 (15)	0.103 (2)
H18A	0.1856	1.0682	−0.0220	0.155*
H18B	0.0862	0.9012	−0.0446	0.155*
H18C	0.2098	0.8137	−0.0300	0.155*
C16	0.1819 (4)	1.0139 (9)	0.06301 (18)	0.0712 (16)
H16A	0.2086	1.1554	0.0582	0.085*
C27	0.5726 (5)	1.0641 (15)	0.4766 (2)	0.097 (2)
H27A	0.6217	1.1072	0.4609	0.117*
C28	0.5207 (6)	0.8584 (14)	0.4683 (2)	0.096 (2)
H28A	0.5347	0.7606	0.4466	0.115*
C29	0.4494 (5)	0.7940 (10)	0.4912 (3)	0.0953 (19)
H29A	0.4151	0.6528	0.4850	0.114*
C25	0.4963 (4)	1.0693 (9)	0.33788 (16)	0.0753 (16)
H25A	0.5136	1.1949	0.3577	0.090*
C26	0.3953 (4)	1.0623 (9)	0.30149 (15)	0.0639 (14)
H26A	0.3452	1.1819	0.2973	0.077*
C21	0.3688 (4)	0.8798 (8)	0.27155 (15)	0.0491 (12)
C23	0.5458 (4)	0.7128 (9)	0.31572 (17)	0.0740 (16)
H23A	0.5962	0.5933	0.3204	0.089*
C24	0.5710 (4)	0.8955 (10)	0.34533 (16)	0.0727 (16)
H24A	0.6381	0.9011	0.3702	0.087*
C22	0.4449 (4)	0.7045 (8)	0.27852 (15)	0.0615 (14)
H22A	0.4288	0.5804	0.2583	0.074*
C20	0.2610 (4)	0.8690 (8)	0.23220 (14)	0.0444 (11)
C19	0.2214 (4)	0.7014 (8)	0.20194 (14)	0.0503 (12)
H19A	0.2636	0.5696	0.2056	0.060*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.045 (2)	0.052 (2)	0.063 (2)	0.0056 (18)	0.0123 (16)	−0.0046 (16)
C5	0.052 (4)	0.057 (4)	0.044 (3)	0.002 (3)	0.019 (3)	0.012 (2)
C10	0.054 (3)	0.050 (3)	0.037 (3)	−0.004 (3)	0.017 (2)	0.006 (2)
C1	0.051 (3)	0.041 (3)	0.041 (3)	0.005 (2)	0.020 (2)	0.002 (2)
C11	0.054 (3)	0.045 (3)	0.042 (3)	−0.003 (2)	0.019 (2)	−0.001 (2)
C12	0.045 (3)	0.046 (3)	0.045 (3)	0.002 (2)	0.015 (2)	−0.002 (2)
C2	0.051 (3)	0.050 (3)	0.044 (3)	0.005 (3)	0.023 (3)	0.004 (2)
C9	0.051 (4)	0.072 (4)	0.053 (3)	0.000 (3)	0.016 (3)	0.009 (3)
C3	0.058 (3)	0.047 (3)	0.045 (3)	0.005 (3)	0.017 (2)	0.004 (2)
C6	0.053 (4)	0.087 (4)	0.058 (3)	0.017 (3)	0.016 (3)	0.015 (3)
C4	0.064 (4)	0.058 (4)	0.048 (3)	0.013 (3)	0.023 (3)	0.003 (3)
C8	0.069 (4)	0.071 (4)	0.061 (3)	−0.008 (3)	0.013 (3)	0.010 (3)
C13	0.087 (4)	0.060 (4)	0.063 (3)	−0.004 (3)	0.036 (3)	−0.010 (3)
C17	0.081 (4)	0.055 (4)	0.054 (3)	−0.011 (3)	0.028 (3)	−0.006 (3)
C15	0.059 (4)	0.093 (5)	0.047 (3)	0.013 (3)	0.024 (3)	0.005 (3)
C7	0.057 (4)	0.094 (5)	0.065 (4)	−0.003 (4)	0.013 (3)	0.015 (3)
C14	0.081 (4)	0.092 (5)	0.053 (3)	−0.009 (3)	0.022 (3)	−0.024 (3)
C18	0.101 (5)	0.157 (6)	0.061 (4)	0.027 (4)	0.040 (3)	0.025 (4)
C16	0.088 (4)	0.068 (4)	0.069 (4)	0.002 (3)	0.041 (3)	0.011 (3)
C27	0.082 (5)	0.116 (6)	0.093 (5)	−0.011 (5)	0.027 (4)	0.016 (4)
C28	0.080 (5)	0.112 (7)	0.093 (5)	−0.003 (4)	0.026 (4)	−0.014 (4)
C29	0.082 (5)	0.082 (5)	0.111 (6)	−0.018 (4)	0.017 (4)	−0.002 (4)
C25	0.075 (4)	0.085 (5)	0.059 (4)	0.001 (4)	0.012 (3)	−0.012 (3)
C26	0.060 (4)	0.070 (4)	0.053 (3)	0.014 (3)	0.007 (3)	−0.006 (3)
C21	0.049 (3)	0.056 (3)	0.047 (3)	0.009 (3)	0.023 (2)	0.007 (3)
C23	0.059 (4)	0.095 (5)	0.063 (4)	0.020 (3)	0.012 (3)	0.003 (3)
C24	0.054 (4)	0.110 (5)	0.047 (3)	0.003 (4)	0.007 (3)	−0.004 (3)
C22	0.054 (4)	0.070 (4)	0.058 (3)	0.008 (3)	0.015 (3)	−0.003 (3)
C20	0.039 (3)	0.051 (3)	0.048 (3)	0.005 (3)	0.019 (2)	0.006 (2)
C19	0.058 (3)	0.048 (3)	0.042 (3)	0.007 (3)	0.013 (2)	0.002 (2)

Geometric parameters (Å, º) top

O1—C20	1.386 (4)	C15—C14	1.379 (6)
O1—C2	1.392 (5)	C15—C18	1.534 (6)
C5—C4	1.410 (5)	C7—H7A	0.9300
C5—C6	1.422 (6)	C14—H14A	0.9300
C5—C10	1.427 (5)	C18—H18A	0.9600
C10—C9	1.415 (5)	C18—H18B	0.9600
C10—C1	1.424 (5)	C18—H18C	0.9600
C1—C2	1.366 (5)	C16—H16A	0.9300
C1—C11	1.498 (5)	C27—C28	1.364 (7)
C11—C19	1.495 (5)	C27—C29ⁱ	1.374 (7)
C11—C12	1.523 (5)	C27—H27A	0.9300
C11—H11A	0.9800	C28—C29	1.353 (7)
C12—C13	1.369 (5)	C28—H28A	0.9300
C12—C17	1.375 (5)	C29—C27ⁱ	1.374 (7)
C2—C3	1.405 (5)	C29—H29A	0.9300
C9—C8	1.376 (6)	C25—C24	1.363 (6)
C9—H9A	0.9300	C25—C26	1.383 (5)
C3—C4	1.355 (5)	C25—H25A	0.9300
C3—H3A	0.9300	C26—C21	1.372 (5)
C6—C7	1.361 (6)	C26—H26A	0.9300
C6—H6A	0.9300	C21—C22	1.383 (5)
C4—H4A	0.9300	C21—C20	1.484 (5)
C8—C7	1.404 (6)	C23—C24	1.367 (6)
C8—H8A	0.9300	C23—C22	1.394 (5)
C13—C14	1.391 (6)	C23—H23A	0.9300
C13—H13A	0.9300	C24—H24A	0.9300
C17—C16	1.376 (5)	C22—H22A	0.9300
C17—H17A	0.9300	C20—C19	1.325 (5)
C15—C16	1.372 (6)	C19—H19A	0.9300

C20—O1—C2	117.0 (3)	C6—C7—H7A	119.9
C4—C5—C6	122.4 (5)	C8—C7—H7A	119.9
C4—C5—C10	118.6 (4)	C15—C14—C13	120.9 (5)
C6—C5—C10	119.0 (5)	C15—C14—H14A	119.6
C9—C10—C1	121.6 (4)	C13—C14—H14A	119.6
C9—C10—C5	117.8 (4)	C15—C18—H18A	109.5
C1—C10—C5	120.6 (4)	C15—C18—H18B	109.5
C2—C1—C10	116.9 (4)	H18A—C18—H18B	109.5
C2—C1—C11	119.8 (4)	C15—C18—H18C	109.5
C10—C1—C11	123.3 (4)	H18A—C18—H18C	109.5
C19—C11—C1	109.1 (3)	H18B—C18—H18C	109.5
C19—C11—C12	111.7 (3)	C15—C16—C17	120.9 (5)
C1—C11—C12	111.9 (3)	C15—C16—H16A	119.5
C19—C11—H11A	108.0	C17—C16—H16A	119.5
C1—C11—H11A	108.0	C28—C27—C29ⁱ	118.3 (6)
C12—C11—H11A	108.0	C28—C27—H27A	120.8
C13—C12—C17	116.7 (4)	C29ⁱ—C27—H27A	120.8
C13—C12—C11	121.7 (4)	C29—C28—C27	121.3 (6)
C17—C12—C11	121.6 (4)	C29—C28—H28A	119.4
C1—C2—O1	122.8 (4)	C27—C28—H28A	119.4
C1—C2—C3	123.6 (4)	C28—C29—C27ⁱ	120.4 (6)
O1—C2—C3	113.6 (4)	C28—C29—H29A	119.8
C8—C9—C10	121.9 (5)	C27ⁱ—C29—H29A	119.8
C8—C9—H9A	119.1	C24—C25—C26	121.3 (5)
C10—C9—H9A	119.1	C24—C25—H25A	119.4
C4—C3—C2	119.4 (4)	C26—C25—H25A	119.4
C4—C3—H3A	120.3	C21—C26—C25	120.3 (5)
C2—C3—H3A	120.3	C21—C26—H26A	119.8
C7—C6—C5	121.3 (5)	C25—C26—H26A	119.8
C7—C6—H6A	119.4	C26—C21—C22	118.7 (4)
C5—C6—H6A	119.4	C26—C21—C20	121.2 (4)
C3—C4—C5	120.8 (4)	C22—C21—C20	120.1 (4)
C3—C4—H4A	119.6	C24—C23—C22	120.3 (5)
C5—C4—H4A	119.6	C24—C23—H23A	119.8
C9—C8—C7	119.8 (5)	C22—C23—H23A	119.8
C9—C8—H8A	120.1	C25—C24—C23	119.1 (5)
C7—C8—H8A	120.1	C25—C24—H24A	120.5
C12—C13—C14	121.6 (5)	C23—C24—H24A	120.5
C12—C13—H13A	119.2	C21—C22—C23	120.3 (5)
C14—C13—H13A	119.2	C21—C22—H22A	119.8
C12—C17—C16	122.3 (4)	C23—C22—H22A	119.8
C12—C17—H17A	118.8	C19—C20—O1	120.9 (4)
C16—C17—H17A	118.8	C19—C20—C21	128.3 (4)
C16—C15—C14	117.5 (4)	O1—C20—C21	110.8 (4)
C16—C15—C18	121.5 (5)	C20—C19—C11	123.8 (4)
C14—C15—C18	120.9 (5)	C20—C19—H19A	118.1
C6—C7—C8	120.3 (5)	C11—C19—H19A	118.1

Symmetry code: (i) −x+1, −y+2, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C26—H26A···O1	0.93	2.34	2.692 (6)	102

Experimental details

Crystal data
Chemical formula	C₂₆H₂₀O·0.5C₆H₆
M_r	387.47
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	12.653 (3), 5.9049 (12), 29.974 (8)
β (°)	109.08 (3)
V (Å³)	2116.5 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.07
Crystal size (mm)	0.20 × 0.20 × 0.20

Data collection
Diffractometer	Rigaku Mercury2 diffractometer
Absorption correction	Multi-scan (CrystalClear; Rigaku, 2005)
T_min, T_max	0.813, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	14405, 3623, 1438
R_int	0.148
(sin θ/λ)_max (Å⁻¹)	0.590

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.080, 0.144, 0.93
No. of reflections	3623
No. of parameters	273
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.18, −0.20

Computer programs: CrystalClear (Rigaku, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

This work was supported by the Natural Science Foundation (grant No. 04KJD150112) of the Jiangsu Provincial Education Department.

References

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