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Acta Cryst. (2009). E65, o1464    [ doi:10.1107/S1600536809020248 ]

3',6'-Bis(diethylamino)-2-phenylspiro[isoindoline-1,9'-xanthen]-3-one

W.-J. Deng, D. Sun, B.-Y. Su, S.-P. Wang and H. Zheng

Abstract top

The title compound, C34H35O2N3, was synthesized by the reaction of 2-[3,6-bis(diethylamino)-9H-xanthen-9-yl]benzoyl chloride with aniline. In the molecular structure, the dihedral angles between the isoindoline and xanthene planes and between the isoindoline and benzene planes are 86.9 (3) and 47.0 (2)°, respectively. The molecular packing in the crystal structure is stabilized by weak C-H...O hydrogen bonding.

Comment top

Rhodamine-based dyes, known by their excellent spectroscopic properties of large molar extinction coefficient and high fluorescence quantum yield (Wu et al., 2007), have found applications in the study of complex biological systems and environmental analysis as molecular probes. In the present paper, the structure of title compound has been determined as part of a research program involving the synthesis and nitric oxide sensing (Zheng et al., 2008).

The molecular structure is depicted in Fig. 1. Bond lengths and angles are in good agreement with previous reported for similar compounds (Kwon et al., 2005). The dihedral angle between isoindoline and xanthene mean planes is 86.9 (3)° The dihedral angle between the isoindoline and benzene ring mean planes is 47.0 (2)°. Weak C—H···O hydrogen bonding (Table 1) helps to stabilize the crystal structure.

Related literature top

For general background, see: Zheng et al. (2008); Wu et al. (2007). For a related structure, see: Kwon et al. (2005).

Experimental top

To a solution of 3',6'-bis(diethylamino)-3H-spiro[isobenzofuran-1,9'- xanthen]-3-one (1.3 g, 2.8 mmol) in dry 1,2-dichloroethane (10.0 ml) at room temperature, phosphorus oxychloride (1.4 g, 8.4 mmol) was added dropwise over a period of 5 min. After being refluxed for 4 h, the reaction mixture was cooled and concentrated under vacuum to give 2-(3,6-bis(diethylamino)-9H-xanthen-9-yl)benzoyl chloride. The chloride salt was dissolved in dry acetonitrile (12.0 ml). This solution was added dropwise to a solution of aniline (1.6 g, 17.5 mmol) in dry acetonitrile (7.5 ml) containing triethylamine (10.0 ml). After stirring for 4 h at room temperature, the mixture was concentrated under vacuum and the crude product was purified by column chromatography (ethyl acetate/dichloromethane, 1:20) to give the title compound as a white solid in 72% yield. Single crystals of the title compound were obtained by slow evaporation of a dichloromethane/methanol solution (5:1 v/v). The product was analyzed by atmospheric-Pressure Chemical Ionization (APCI) mass spectrometry (positive mode). The molecular peak appeared at a mass/charge ratio of 518.5.

Refinement top

H atoms were placed geometrically with C—H = 0.95 (aromatic), 0.98 (methyl) and 0.99 Å (methylene), and refined using a riding atom model with Uiso(H) = 1.5Ueq(C) for methyl and 1.2Ueq(C) for the others.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with 30% probability displacement ellipsoids for non-H atoms.
3',6'-Bis(diethylamino)-2-phenylspiro[isoindoline-1,9'-xanthen]-3-one top
Crystal data top
C34H35N3O2F(000) = 1104
Mr = 517.65Dx = 1.251 Mg m−3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 16600 reflections
a = 12.0213 (5) Åθ = 2.4–32.7°
b = 12.6315 (4) ŵ = 0.08 mm−1
c = 18.9700 (7) ÅT = 173 K
β = 107.456 (4)°Block, colourless
V = 2747.88 (18) Å30.30 × 0.20 × 0.20 mm
Z = 4
Data collection top
Oxford Diffraction Xcalibur
diffractometer with a Sapphire3 (Gemini ultra Mo) detector		4396 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.025
graphiteθmax = 26.0°, θmin = 2.4°
Detector resolution: 16.1903 pixels mm-1h = −14→14
φ and ω scansk = −15→15
29794 measured reflectionsl = −21→23
5403 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.103H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0572P)2 + 0.4462P]
where P = (Fo2 + 2Fc2)/3
5403 reflections(Δ/σ)max = 0.006
352 parametersΔρmax = 0.22 e Å−3
0 restraintsΔρmin = −0.19 e Å−3
Crystal data top
C34H35N3O2V = 2747.88 (18) Å3
Mr = 517.65Z = 4
Monoclinic, P21/nMo Kα radiation
a = 12.0213 (5) ŵ = 0.08 mm−1
b = 12.6315 (4) ÅT = 173 K
c = 18.9700 (7) Å0.30 × 0.20 × 0.20 mm
β = 107.456 (4)°
Data collection top
Oxford Diffraction Xcalibur
diffractometer with a Sapphire3 (Gemini ultra Mo) detector		4396 reflections with I > 2σ(I)
29794 measured reflectionsRint = 0.025
5403 independent reflectionsθmax = 26.0°
Refinement top
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.103Δρmax = 0.22 e Å−3
S = 1.06Δρmin = −0.19 e Å−3
5403 reflectionsAbsolute structure: ?
352 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
C10.71114 (11)0.71818 (10)0.15020 (7)0.0228 (3)
C20.82352 (12)0.71273 (11)0.14514 (8)0.0267 (3)
H2A0.85580.77220.12770.032*
C30.88993 (11)0.62080 (11)0.16541 (7)0.0247 (3)
C40.83537 (12)0.53371 (10)0.18815 (7)0.0240 (3)
H4A0.87670.46900.20110.029*
C50.72318 (11)0.54138 (10)0.19186 (7)0.0219 (3)
H5A0.68930.48150.20770.026*
C60.65727 (11)0.63372 (10)0.17327 (7)0.0192 (3)
C70.53398 (11)0.64059 (10)0.17788 (7)0.0192 (3)
C80.48969 (11)0.75350 (9)0.16449 (7)0.0192 (3)
C90.38198 (11)0.78341 (10)0.17203 (7)0.0212 (3)
H9A0.33810.73210.18900.025*
C100.33646 (11)0.88340 (10)0.15613 (7)0.0225 (3)
H10A0.26240.89950.16170.027*
C110.39947 (11)0.96252 (10)0.13143 (7)0.0219 (3)
C120.50750 (12)0.93349 (10)0.12374 (7)0.0235 (3)
H12A0.55240.98440.10730.028*
C130.54985 (11)0.83143 (10)0.13973 (7)0.0214 (3)
C140.44953 (11)0.56635 (10)0.12430 (7)0.0214 (3)
C150.41783 (12)0.56501 (11)0.04796 (8)0.0275 (3)
H15A0.45070.61370.02160.033*
C160.33642 (13)0.49019 (12)0.01089 (8)0.0340 (4)
H16A0.31430.4871−0.04150.041*
C170.28681 (13)0.41981 (12)0.04928 (9)0.0349 (4)
H17A0.23070.36980.02280.042*
C180.31836 (12)0.42201 (11)0.12532 (9)0.0308 (3)
H18A0.28470.37430.15190.037*
C190.40063 (11)0.49595 (10)0.16190 (8)0.0235 (3)
C200.45099 (12)0.51313 (10)0.24234 (8)0.0237 (3)
C210.60912 (11)0.62493 (10)0.31955 (7)0.0219 (3)
C220.66767 (14)0.54632 (12)0.36746 (8)0.0341 (3)
H22A0.65360.47390.35420.041*
C230.74656 (14)0.57334 (13)0.43449 (8)0.0393 (4)
H23A0.78520.51920.46760.047*
C240.76971 (14)0.67813 (13)0.45384 (8)0.0385 (4)
H24A0.82400.69650.49990.046*
C250.71330 (15)0.75539 (13)0.40563 (9)0.0439 (4)
H25A0.72970.82770.41820.053*
C260.63245 (14)0.72939 (11)0.33859 (8)0.0360 (4)
H26A0.59330.78380.30590.043*
C270.41811 (13)1.14312 (11)0.08587 (8)0.0327 (3)
H27A0.36091.19470.05630.039*
H27B0.45591.10810.05230.039*
C280.51015 (15)1.20246 (12)0.14500 (10)0.0418 (4)
H28A0.54871.25410.12160.063*
H28B0.56811.15220.17400.063*
H28C0.47321.23940.17760.063*
C290.25151 (14)1.09900 (12)0.13220 (9)0.0372 (4)
H29A0.26111.17440.14700.045*
H29B0.24311.05790.17470.045*
C300.14156 (16)1.08697 (19)0.06812 (11)0.0630 (6)
H30A0.07471.11240.08270.094*
H30B0.13021.01220.05400.094*
H30C0.14851.12850.02600.094*
C311.06594 (13)0.70793 (12)0.15060 (10)0.0379 (4)
H31A1.14790.70480.18250.045*
H31B1.03010.77200.16460.045*
C321.06523 (17)0.71910 (15)0.07113 (10)0.0540 (5)
H32A1.10850.78290.06590.081*
H32B0.98460.72480.03910.081*
H32C1.10220.65690.05690.081*
C331.06374 (13)0.51390 (12)0.17186 (8)0.0319 (3)
H33A1.05130.47450.21400.038*
H33B1.14850.52660.18310.038*
C341.02314 (13)0.44583 (12)0.10308 (9)0.0364 (4)
H34A1.06640.37890.11130.055*
H34B1.03720.48330.06130.055*
H34C0.93960.43130.09220.055*
N10.35614 (10)1.06343 (9)0.11526 (7)0.0306 (3)
N21.00455 (10)0.61526 (10)0.16542 (7)0.0332 (3)
N30.52732 (9)0.59642 (8)0.25021 (6)0.0205 (2)
O10.65733 (8)0.81453 (7)0.12950 (6)0.0307 (2)
O20.42961 (9)0.46357 (8)0.29198 (6)0.0345 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0214 (7)0.0196 (6)0.0281 (7)0.0008 (5)0.0084 (6)−0.0007 (5)
C20.0222 (7)0.0232 (7)0.0372 (8)−0.0038 (5)0.0128 (6)−0.0019 (6)
C30.0176 (7)0.0295 (7)0.0257 (7)0.0001 (5)0.0045 (5)−0.0075 (6)
C40.0218 (7)0.0243 (7)0.0244 (7)0.0057 (5)0.0048 (5)−0.0009 (5)
C50.0229 (7)0.0223 (7)0.0203 (6)−0.0001 (5)0.0064 (5)0.0006 (5)
C60.0169 (6)0.0216 (6)0.0188 (6)−0.0003 (5)0.0048 (5)−0.0016 (5)
C70.0177 (6)0.0211 (6)0.0187 (6)−0.0007 (5)0.0053 (5)0.0013 (5)
C80.0180 (6)0.0198 (6)0.0188 (6)−0.0001 (5)0.0040 (5)−0.0001 (5)
C90.0185 (7)0.0229 (7)0.0221 (6)−0.0016 (5)0.0060 (5)0.0013 (5)
C100.0169 (6)0.0252 (7)0.0241 (6)0.0025 (5)0.0041 (5)−0.0009 (5)
C110.0217 (7)0.0204 (6)0.0207 (6)0.0029 (5)0.0019 (5)0.0002 (5)
C120.0231 (7)0.0206 (7)0.0275 (7)−0.0015 (5)0.0085 (6)0.0036 (5)
C130.0180 (7)0.0229 (7)0.0232 (6)0.0007 (5)0.0062 (5)0.0001 (5)
C140.0153 (6)0.0205 (6)0.0273 (7)0.0032 (5)0.0049 (5)−0.0040 (5)
C150.0227 (7)0.0306 (7)0.0285 (7)0.0033 (6)0.0068 (6)−0.0008 (6)
C160.0259 (8)0.0414 (9)0.0286 (7)0.0081 (6)−0.0012 (6)−0.0116 (6)
C170.0207 (7)0.0287 (8)0.0492 (9)−0.0006 (6)0.0015 (7)−0.0164 (7)
C180.0219 (7)0.0220 (7)0.0483 (9)0.0001 (6)0.0100 (6)−0.0046 (6)
C190.0181 (7)0.0194 (6)0.0334 (7)0.0035 (5)0.0083 (6)−0.0026 (5)
C200.0217 (7)0.0186 (6)0.0341 (7)0.0024 (5)0.0132 (6)0.0022 (5)
C210.0197 (7)0.0269 (7)0.0197 (6)0.0037 (5)0.0071 (5)−0.0011 (5)
C220.0398 (9)0.0287 (8)0.0311 (8)0.0039 (7)0.0065 (7)0.0052 (6)
C230.0395 (9)0.0459 (10)0.0277 (8)0.0082 (7)0.0029 (7)0.0120 (7)
C240.0360 (9)0.0513 (10)0.0233 (7)0.0056 (7)0.0014 (6)−0.0050 (7)
C250.0471 (10)0.0341 (9)0.0377 (9)0.0041 (7)−0.0069 (8)−0.0114 (7)
C260.0410 (9)0.0259 (7)0.0318 (8)0.0069 (6)−0.0033 (7)0.0000 (6)
C270.0348 (8)0.0229 (7)0.0407 (8)0.0070 (6)0.0118 (7)0.0098 (6)
C280.0411 (10)0.0309 (8)0.0529 (10)0.0000 (7)0.0131 (8)0.0054 (7)
C290.0386 (9)0.0259 (7)0.0519 (10)0.0125 (7)0.0209 (8)0.0079 (7)
C300.0363 (10)0.0903 (16)0.0623 (12)0.0247 (10)0.0148 (9)0.0299 (11)
C310.0181 (7)0.0366 (9)0.0593 (11)−0.0060 (6)0.0123 (7)−0.0130 (7)
C320.0554 (12)0.0458 (10)0.0569 (11)−0.0162 (9)0.0110 (9)0.0081 (9)
C330.0193 (7)0.0420 (9)0.0339 (8)0.0091 (6)0.0075 (6)0.0021 (6)
C340.0303 (8)0.0384 (8)0.0430 (9)0.0028 (7)0.0149 (7)−0.0043 (7)
N10.0279 (7)0.0227 (6)0.0424 (7)0.0074 (5)0.0123 (6)0.0073 (5)
N20.0184 (6)0.0320 (7)0.0504 (8)0.0006 (5)0.0123 (6)−0.0056 (6)
N30.0212 (6)0.0196 (5)0.0215 (5)−0.0002 (4)0.0075 (4)0.0022 (4)
O10.0242 (5)0.0210 (5)0.0540 (7)0.0036 (4)0.0225 (5)0.0089 (4)
O20.0385 (6)0.0315 (6)0.0391 (6)−0.0055 (5)0.0202 (5)0.0072 (4)
Geometric parameters (Å, °) top
C1—O11.3789 (15)C21—C221.3870 (19)
C1—C21.3846 (19)C21—N31.4320 (16)
C1—C61.3854 (18)C22—C231.382 (2)
C2—C31.3961 (19)C22—H22A0.9500
C2—H2A0.9500C23—C241.380 (2)
C3—N21.3796 (18)C23—H23A0.9500
C3—C41.413 (2)C24—C251.370 (2)
C4—C51.3749 (19)C24—H24A0.9500
C4—H4A0.9500C25—C261.389 (2)
C5—C61.3945 (18)C25—H25A0.9500
C5—H5A0.9500C26—H26A0.9500
C6—C71.5131 (18)C27—N11.4588 (19)
C7—N31.5054 (16)C27—C281.516 (2)
C7—C81.5170 (17)C27—H27A0.9900
C7—C141.5245 (17)C27—H27B0.9900
C8—C131.3842 (18)C28—H28A0.9800
C8—C91.3967 (18)C28—H28B0.9800
C9—C101.3735 (18)C28—H28C0.9800
C9—H9A0.9500C29—N11.4593 (19)
C10—C111.4161 (19)C29—C301.511 (3)
C10—H10A0.9500C29—H29A0.9900
C11—N11.3763 (17)C29—H29B0.9900
C11—C121.3985 (19)C30—H30A0.9800
C12—C131.3858 (18)C30—H30B0.9800
C12—H12A0.9500C30—H30C0.9800
C13—O11.3795 (16)C31—N21.4555 (19)
C14—C191.3773 (19)C31—C321.512 (3)
C14—C151.3826 (19)C31—H31A0.9900
C15—C161.390 (2)C31—H31B0.9900
C15—H15A0.9500C32—H32A0.9800
C16—C171.392 (2)C32—H32B0.9800
C16—H16A0.9500C32—H32C0.9800
C17—C181.377 (2)C33—N21.4520 (18)
C17—H17A0.9500C33—C341.516 (2)
C18—C191.3858 (19)C33—H33A0.9900
C18—H18A0.9500C33—H33B0.9900
C19—C201.4790 (19)C34—H34A0.9800
C20—O21.2207 (16)C34—H34B0.9800
C20—N31.3744 (17)C34—H34C0.9800
C21—C261.3744 (19)
O1—C1—C2114.10 (11)C24—C23—H23A119.7
O1—C1—C6123.08 (12)C22—C23—H23A119.7
C2—C1—C6122.81 (12)C25—C24—C23119.08 (14)
C1—C2—C3120.76 (12)C25—C24—H24A120.5
C1—C2—H2A119.6C23—C24—H24A120.5
C3—C2—H2A119.6C24—C25—C26120.88 (15)
N2—C3—C2122.06 (13)C24—C25—H25A119.6
N2—C3—C4121.03 (12)C26—C25—H25A119.6
C2—C3—C4116.88 (12)C21—C26—C25119.95 (13)
C5—C4—C3120.87 (12)C21—C26—H26A120.0
C5—C4—H4A119.6C25—C26—H26A120.0
C3—C4—H4A119.6N1—C27—C28113.66 (13)
C4—C5—C6122.52 (12)N1—C27—H27A108.8
C4—C5—H5A118.7C28—C27—H27A108.8
C6—C5—H5A118.7N1—C27—H27B108.8
C1—C6—C5116.11 (12)C28—C27—H27B108.8
C1—C6—C7122.20 (11)H27A—C27—H27B107.7
C5—C6—C7121.69 (11)C27—C28—H28A109.5
N3—C7—C6110.63 (10)C27—C28—H28B109.5
N3—C7—C8112.90 (10)H28A—C28—H28B109.5
C6—C7—C8110.18 (10)C27—C28—H28C109.5
N3—C7—C1499.96 (10)H28A—C28—H28C109.5
C6—C7—C14113.21 (10)H28B—C28—H28C109.5
C8—C7—C14109.67 (10)N1—C29—C30113.30 (15)
C13—C8—C9115.92 (11)N1—C29—H29A108.9
C13—C8—C7122.18 (12)C30—C29—H29A108.9
C9—C8—C7121.79 (11)N1—C29—H29B108.9
C10—C9—C8123.15 (12)C30—C29—H29B108.9
C10—C9—H9A118.4H29A—C29—H29B107.7
C8—C9—H9A118.4C29—C30—H30A109.5
C9—C10—C11120.28 (12)C29—C30—H30B109.5
C9—C10—H10A119.9H30A—C30—H30B109.5
C11—C10—H10A119.9C29—C30—H30C109.5
N1—C11—C12121.39 (12)H30A—C30—H30C109.5
N1—C11—C10121.54 (12)H30B—C30—H30C109.5
C12—C11—C10117.07 (11)N2—C31—C32114.59 (13)
C13—C12—C11120.85 (12)N2—C31—H31A108.6
C13—C12—H12A119.6C32—C31—H31A108.6
C11—C12—H12A119.6N2—C31—H31B108.6
O1—C13—C8122.99 (11)C32—C31—H31B108.6
O1—C13—C12114.28 (11)H31A—C31—H31B107.6
C8—C13—C12122.73 (12)C31—C32—H32A109.5
C19—C14—C15120.55 (12)C31—C32—H32B109.5
C19—C14—C7110.74 (11)H32A—C32—H32B109.5
C15—C14—C7128.69 (12)C31—C32—H32C109.5
C14—C15—C16117.98 (14)H32A—C32—H32C109.5
C14—C15—H15A121.0H32B—C32—H32C109.5
C16—C15—H15A121.0N2—C33—C34113.87 (12)
C15—C16—C17121.11 (14)N2—C33—H33A108.8
C15—C16—H16A119.4C34—C33—H33A108.8
C17—C16—H16A119.4N2—C33—H33B108.8
C18—C17—C16120.57 (13)C34—C33—H33B108.8
C18—C17—H17A119.7H33A—C33—H33B107.7
C16—C17—H17A119.7C33—C34—H34A109.5
C17—C18—C19117.97 (14)C33—C34—H34B109.5
C17—C18—H18A121.0H34A—C34—H34B109.5
C19—C18—H18A121.0C33—C34—H34C109.5
C14—C19—C18121.81 (13)H34A—C34—H34C109.5
C14—C19—C20109.47 (11)H34B—C34—H34C109.5
C18—C19—C20128.71 (13)C11—N1—C27121.45 (12)
O2—C20—N3126.65 (13)C11—N1—C29121.98 (12)
O2—C20—C19127.22 (13)C27—N1—C29116.38 (11)
N3—C20—C19106.13 (11)C3—N2—C33120.59 (12)
C26—C21—C22119.45 (13)C3—N2—C31121.56 (12)
C26—C21—N3120.83 (12)C33—N2—C31117.48 (12)
C22—C21—N3119.70 (12)C20—N3—C21122.99 (11)
C23—C22—C21119.97 (14)C20—N3—C7113.63 (10)
C23—C22—H22A120.0C21—N3—C7122.30 (10)
C21—C22—H22A120.0C1—O1—C13118.40 (10)
C24—C23—C22120.65 (14)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C31—H31B···O2i0.992.563.4032 (19)144
Symmetry codes: (i) −x+3/2, y+1/2, −z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C31—H31B···O2i0.992.563.4032 (19)144
Symmetry codes: (i) −x+3/2, y+1/2, −z+1/2.
Acknowledgements top

The authors thank the Science Research Foundation of Xiamen University (No. E43011) and the National Natural Science Foundation of China (No. 20675067) for supporting this work. We also thank Mr S.-Y. Yang and Mr Z.-B. Wei for technical assistance.

references
References top

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Kwon, J. Y., Jang, Y. J., Lee, Y. J., Kim, K. M., Seo, M. S., Nam, W. & Yoon, J. (2005). J. Am. Chem. Soc. 127, 10107–10111.

Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Wu, D., Huang, W., Duan, C. Y., Lin, Z. H. & Meng, Q. J. (2007). Inorg. Chem. 46, 1538–1540.

Zheng, H., Shang, G. Q., Yang, S. Y., Gao, X. & Xu, J. G. (2008). Org. Lett. 10, 2357–2360.