supplementary materials


sj2754 scheme

Acta Cryst. (2010). E66, o963    [ doi:10.1107/S1600536810011086 ]

10-(1,3-Benzothiazol-2-yl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[3,2-g]pyrido[3,2,1-hi]quinoline

K.-M. Park and Y. Kang

Abstract top

In the title compound, C26H26N2O2S, the dihedral angle between the benzothiazole and coumarin rings is 8.34 (7)°, indicating that the overall benzothiazole substituent is almost coplanar with the coumarin rings. An intramolecular S...O [2.813 (1) Å] contact may help to stabilize the molecular conformation. In the crystal structure, [pi]-[pi] stacking interactions [centroid-centroid distances = 3.480 (2) Å] link pairs of molecules.

Comment top

Luminescent compounds have attracted much attention owing to their varied applications, such as in photonics and as organic light-emitting diodes (Lee et al., 2009). Among such luminescent compounds, 10-(2-Benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H- benzo[l]pyr ano[6,7,8-ij] quinolizin-11-one, often referred as C545T, is regarded as an excellent fluorescent compound and has been widely studied because of its ability to achieve high external quantum efficiency in organic light-emitting diodes (White et al., 2010). Therefore, as a good emitter the structure of C545T is of interest to materials chemists.

In the title compound (Scheme 1, Fig.1), the benzothiazole and coumarin segments lie in the same plane with a dihedral angle of 8.34 (7)° between the respective planes. This coplanarity may be assisted by a short intramolecular contact (2.813 (1) Å) between S1 and O1 (Mellor et al., 1971; Kucsman et al., 1984). All bond lengths and bond angles are normal and comparable to those of observed in the structures of coumarin and benzothiazole derivatives (Gavuzzo et al., 1974; Chinnakali et al., 1999; Padilla-Martínez et al., 2003).

A ππ stacking interaction is observed between two adjacent coumarin segments in the crystal packing is observed [C12···C9i = 3.480 (2) Å; Cg1···Cg1i = 3.778 Å; where Cg1 is the centroid of the O2, C8–C12 ring; symmetry code (i) 1-x, 1-y, 1-z] (Fig. 2).

Related literature top

For background to organic light-emitting diodes (OLEDs), see: Lee et al. (2009). For the use of the title compound as an organic light-emitting diode, see: White et al.(2010). For S···O interactions, see: Mellor et al. (1971); Kucsman et al. (1984). For the crystal structure of benzothiazole-ethylcoumarin, see: Padilla-Martínez et al. (2003) and for that of coumarin, see: Gavuzzo et al. (1974); Chinnakali et al. (1999).

Experimental top

10-(2-Benzothiazolyl)-1,1,7,7-tetramethyl- 2,3,6,7-tetrahydro-1H,5H,11H-benzo[l] pyrano[6,7,8-ij]quinolizin-11-one (C545T) was purchased from the Aldrich Chemical Company. Slow evaporation of a solution of CH2Cl2 and hexane (1:1, v:v) gave suitable single crystals for X-ray analysis.

Refinement top

All H-atoms were positioned geometrically and refined using a riding model with d(C—H) = 0.95 Å, Uiso =1.2Ueq(C) for aromatic, 0.99 Å, Uiso = 1.2Ueq(C) for CH2, and 0.98 Å, Uiso = 1.5Ueq(C) for CH3 atoms.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT-Plus (Bruker, 2000); data reduction: SAINT-Plus (Bruker, 2000); 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
[Figure 1] Fig. 1. The molecular structure of title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level; hydrogen atoms are drawn as spheres of arbitrary radius.
[Figure 2] Fig. 2. ππ interactions (dotted lines) in the title compound. Cg denotes the O2, C8–C12 ring centroid. [Symmetry codes: (i) -x+1,-y+1,-z+1.]
10-(1,3-Benzothiazol-2-yl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro- 1H,5H,11H-pyrano[3,2-g]pyrido[3,2,1- hi]quinoline top
Crystal data top
C26H26N2O2SF(000) = 912
Mr = 430.55Dx = 1.346 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 7330 reflections
a = 9.2180 (4) Åθ = 2.4–28.3°
b = 13.7079 (6) ŵ = 0.18 mm1
c = 18.6885 (6) ÅT = 173 K
β = 115.890 (2)°Block, orange
V = 2124.46 (15) Å30.50 × 0.40 × 0.40 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer
3592 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.030
graphiteθmax = 26.0°, θmin = 1.9°
φ and ω scansh = 119
11820 measured reflectionsk = 1216
4179 independent reflectionsl = 2023
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)] = 0.036Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.100H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.044P)2 + 1.0847P]
where P = (Fo2 + 2Fc2)/3
4179 reflections(Δ/σ)max = 0.001
280 parametersΔρmax = 0.31 e Å3
0 restraintsΔρmin = 0.28 e Å3
Crystal data top
C26H26N2O2SV = 2124.46 (15) Å3
Mr = 430.55Z = 4
Monoclinic, P21/cMo Kα radiation
a = 9.2180 (4) ŵ = 0.18 mm1
b = 13.7079 (6) ÅT = 173 K
c = 18.6885 (6) Å0.50 × 0.40 × 0.40 mm
β = 115.890 (2)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
3592 reflections with I > 2σ(I)
11820 measured reflectionsRint = 0.030
4179 independent reflectionsθmax = 26.0°
Refinement top
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.100Δρmax = 0.31 e Å3
S = 1.06Δρmin = 0.28 e Å3
4179 reflectionsAbsolute structure: ?
280 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
S10.19362 (5)0.61269 (3)0.29844 (2)0.02617 (12)
O10.48027 (14)0.50800 (9)0.33612 (7)0.0319 (3)
O20.57724 (12)0.38158 (8)0.41606 (6)0.0239 (2)
N10.06477 (15)0.51630 (9)0.37615 (8)0.0241 (3)
N20.79705 (17)0.09754 (10)0.57717 (8)0.0288 (3)
C10.0975 (2)0.72222 (13)0.23952 (10)0.0329 (4)
H10.06490.76330.20830.039*
C20.2464 (2)0.73381 (13)0.23991 (11)0.0362 (4)
H20.31640.78410.20880.043*
C30.2958 (2)0.67300 (13)0.28511 (10)0.0311 (4)
H30.39930.68200.28360.037*
C40.19676 (19)0.60012 (12)0.33190 (10)0.0272 (3)
H40.23050.55940.36300.033*
C50.04516 (18)0.58726 (11)0.33269 (9)0.0236 (3)
C60.19373 (18)0.52131 (11)0.36444 (9)0.0214 (3)
C70.00332 (19)0.64804 (12)0.28657 (9)0.0252 (3)
C80.32875 (18)0.45412 (11)0.40379 (9)0.0217 (3)
C90.32966 (18)0.38973 (11)0.45990 (9)0.0232 (3)
H90.24540.39290.47610.028*
C100.45101 (18)0.31905 (11)0.49446 (9)0.0218 (3)
C110.57626 (18)0.31438 (11)0.47106 (9)0.0210 (3)
C120.46105 (18)0.45318 (11)0.38203 (9)0.0228 (3)
C130.44984 (18)0.24849 (11)0.54910 (9)0.0233 (3)
H130.36750.25120.56660.028*
C140.56330 (18)0.17633 (11)0.57769 (9)0.0219 (3)
C150.68816 (18)0.17229 (11)0.55131 (9)0.0219 (3)
C160.69810 (18)0.24492 (11)0.49835 (9)0.0214 (3)
C170.56258 (19)0.10207 (11)0.63862 (9)0.0243 (3)
C180.6185 (2)0.00427 (12)0.61992 (10)0.0316 (4)
H18A0.62250.04490.65960.038*
H18B0.53970.01840.56680.038*
C190.7820 (3)0.01276 (14)0.62120 (12)0.0402 (5)
H19A0.86450.01740.67710.048*
H19B0.80400.04720.59800.048*
C200.9368 (2)0.09144 (14)0.56085 (11)0.0352 (4)
H20A0.91560.04320.51800.042*
H20B1.03050.06830.60910.042*
C210.9768 (2)0.18838 (13)0.53606 (10)0.0312 (4)
H21A1.06130.17870.51760.037*
H21B1.02100.23220.58280.037*
C220.82998 (18)0.23758 (11)0.46957 (9)0.0237 (3)
C230.6774 (2)0.13677 (13)0.72253 (10)0.0342 (4)
H23A0.78560.14610.72580.051*
H23B0.68170.08770.76160.051*
H23C0.63830.19870.73380.051*
C240.3950 (2)0.08820 (13)0.63537 (11)0.0342 (4)
H24A0.31970.06600.58210.051*
H24B0.35720.15030.64710.051*
H24D0.40060.03940.67480.051*
C250.7662 (2)0.17553 (14)0.39363 (10)0.0357 (4)
H25A0.67270.20790.35190.054*
H25D0.73400.11120.40460.054*
H25B0.85100.16780.37580.054*
C260.8916 (2)0.33538 (12)0.45338 (10)0.0302 (4)
H26D0.80260.37030.41110.045*
H26A0.97720.32330.43670.045*
H26B0.93450.37490.50200.045*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0285 (2)0.0226 (2)0.0269 (2)0.00232 (16)0.01166 (17)0.00763 (15)
O10.0331 (6)0.0313 (6)0.0365 (6)0.0063 (5)0.0199 (5)0.0135 (5)
O20.0244 (5)0.0235 (6)0.0255 (5)0.0046 (4)0.0126 (5)0.0070 (4)
N10.0239 (7)0.0215 (7)0.0263 (7)0.0020 (5)0.0104 (5)0.0026 (5)
N20.0340 (8)0.0252 (7)0.0295 (7)0.0102 (6)0.0158 (6)0.0076 (6)
C10.0364 (9)0.0253 (8)0.0299 (9)0.0046 (7)0.0079 (7)0.0064 (7)
C20.0345 (9)0.0279 (9)0.0331 (9)0.0109 (7)0.0027 (7)0.0026 (7)
C30.0247 (8)0.0291 (9)0.0316 (9)0.0057 (7)0.0048 (7)0.0065 (7)
C40.0255 (8)0.0239 (8)0.0289 (8)0.0000 (6)0.0088 (7)0.0042 (6)
C50.0256 (8)0.0182 (7)0.0221 (7)0.0015 (6)0.0059 (6)0.0019 (6)
C60.0254 (8)0.0171 (7)0.0206 (7)0.0004 (6)0.0090 (6)0.0008 (6)
C70.0262 (8)0.0218 (8)0.0234 (7)0.0007 (6)0.0072 (6)0.0017 (6)
C80.0227 (7)0.0189 (7)0.0225 (7)0.0002 (6)0.0089 (6)0.0004 (6)
C90.0223 (7)0.0233 (8)0.0249 (8)0.0001 (6)0.0111 (6)0.0011 (6)
C100.0224 (7)0.0209 (7)0.0222 (7)0.0006 (6)0.0097 (6)0.0017 (6)
C110.0240 (7)0.0192 (7)0.0183 (7)0.0015 (6)0.0077 (6)0.0004 (6)
C120.0236 (8)0.0211 (8)0.0218 (7)0.0005 (6)0.0083 (6)0.0018 (6)
C130.0242 (8)0.0241 (8)0.0228 (7)0.0005 (6)0.0114 (6)0.0015 (6)
C140.0261 (8)0.0191 (7)0.0191 (7)0.0014 (6)0.0085 (6)0.0001 (6)
C150.0248 (8)0.0193 (7)0.0182 (7)0.0015 (6)0.0062 (6)0.0011 (6)
C160.0222 (7)0.0210 (7)0.0190 (7)0.0001 (6)0.0073 (6)0.0020 (6)
C170.0310 (8)0.0207 (8)0.0204 (7)0.0005 (6)0.0104 (6)0.0029 (6)
C180.0489 (11)0.0204 (8)0.0282 (8)0.0052 (7)0.0195 (8)0.0059 (7)
C190.0569 (12)0.0296 (9)0.0432 (10)0.0196 (9)0.0304 (9)0.0164 (8)
C200.0344 (9)0.0367 (10)0.0380 (10)0.0154 (8)0.0190 (8)0.0092 (8)
C210.0263 (8)0.0351 (9)0.0316 (9)0.0071 (7)0.0121 (7)0.0031 (7)
C220.0238 (8)0.0244 (8)0.0230 (7)0.0019 (6)0.0102 (6)0.0004 (6)
C230.0467 (10)0.0284 (9)0.0219 (8)0.0023 (8)0.0098 (7)0.0022 (7)
C240.0395 (10)0.0278 (9)0.0390 (10)0.0006 (8)0.0205 (8)0.0098 (7)
C250.0412 (10)0.0386 (10)0.0301 (9)0.0010 (8)0.0181 (8)0.0075 (8)
C260.0242 (8)0.0319 (9)0.0359 (9)0.0005 (7)0.0144 (7)0.0033 (7)
Geometric parameters (Å, °) top
S1—C71.7382 (16)C14—C171.530 (2)
S1—C61.7576 (15)C15—C161.435 (2)
O1—C121.2104 (18)C16—C221.532 (2)
O2—C111.3832 (18)C17—C181.530 (2)
O2—C121.3857 (18)C17—C241.531 (2)
N1—C61.301 (2)C17—C231.535 (2)
N1—C51.383 (2)C18—C191.501 (3)
N2—C151.367 (2)C18—H18A0.9900
N2—C201.450 (2)C18—H18B0.9900
N2—C191.465 (2)C19—H19A0.9900
C1—C21.385 (3)C19—H19B0.9900
C1—C71.399 (2)C20—C211.505 (3)
C1—H10.9500C20—H20A0.9900
C2—C31.397 (3)C20—H20B0.9900
C2—H20.9500C21—C221.537 (2)
C3—C41.378 (2)C21—H21A0.9900
C3—H30.9500C21—H21B0.9900
C4—C51.402 (2)C22—C251.535 (2)
C4—H40.9500C22—C261.537 (2)
C5—C71.405 (2)C23—H23A0.9800
C6—C81.463 (2)C23—H23B0.9800
C8—C91.368 (2)C23—H23C0.9800
C8—C121.444 (2)C24—H24A0.9800
C9—C101.406 (2)C24—H24B0.9800
C9—H90.9500C24—H24D0.9800
C10—C111.403 (2)C25—H25A0.9800
C10—C131.410 (2)C25—H25D0.9800
C11—C161.389 (2)C25—H25B0.9800
C13—C141.367 (2)C26—H26D0.9800
C13—H130.9500C26—H26A0.9800
C14—C151.438 (2)C26—H26B0.9800
C7—S1—C688.83 (7)C14—C17—C23109.21 (13)
C11—O2—C12123.93 (12)C18—C17—C23110.73 (14)
C6—N1—C5110.66 (13)C24—C17—C23108.23 (14)
C15—N2—C20123.48 (14)C19—C18—C17111.36 (14)
C15—N2—C19123.93 (14)C19—C18—H18A109.4
C20—N2—C19112.54 (13)C17—C18—H18A109.4
C2—C1—C7117.92 (16)C19—C18—H18B109.4
C2—C1—H1121.0C17—C18—H18B109.4
C7—C1—H1121.0H18A—C18—H18B108.0
C1—C2—C3121.35 (16)N2—C19—C18113.16 (14)
C1—C2—H2119.3N2—C19—H19A108.9
C3—C2—H2119.3C18—C19—H19A108.9
C4—C3—C2121.03 (16)N2—C19—H19B108.9
C4—C3—H3119.5C18—C19—H19B108.9
C2—C3—H3119.5H19A—C19—H19B107.8
C3—C4—C5118.62 (16)N2—C20—C21111.93 (14)
C3—C4—H4120.7N2—C20—H20A109.2
C5—C4—H4120.7C21—C20—H20A109.2
N1—C5—C4124.45 (14)N2—C20—H20B109.2
N1—C5—C7115.44 (14)C21—C20—H20B109.2
C4—C5—C7120.11 (14)H20A—C20—H20B107.9
N1—C6—C8121.43 (13)C20—C21—C22112.88 (14)
N1—C6—S1115.79 (11)C20—C21—H21A109.0
C8—C6—S1122.77 (11)C22—C21—H21A109.0
C1—C7—C5120.97 (15)C20—C21—H21B109.0
C1—C7—S1129.75 (14)C22—C21—H21B109.0
C5—C7—S1109.27 (11)H21A—C21—H21B107.8
C9—C8—C12119.13 (14)C16—C22—C25108.57 (13)
C9—C8—C6120.73 (14)C16—C22—C21107.36 (12)
C12—C8—C6120.12 (13)C25—C22—C21110.56 (14)
C8—C9—C10122.29 (14)C16—C22—C26115.48 (13)
C8—C9—H9118.9C25—C22—C26109.08 (13)
C10—C9—H9118.9C21—C22—C26105.74 (13)
C11—C10—C9119.09 (14)C17—C23—H23A109.5
C11—C10—C13117.51 (14)C17—C23—H23B109.5
C9—C10—C13123.32 (14)H23A—C23—H23B109.5
O2—C11—C16117.57 (13)C17—C23—H23C109.5
O2—C11—C10118.32 (13)H23A—C23—H23C109.5
C16—C11—C10124.09 (14)H23B—C23—H23C109.5
O1—C12—O2116.23 (13)C17—C24—H24A109.5
O1—C12—C8126.66 (14)C17—C24—H24B109.5
O2—C12—C8117.11 (13)H24A—C24—H24B109.5
C14—C13—C10122.20 (14)C17—C24—H24D109.5
C14—C13—H13118.9H24A—C24—H24D109.5
C10—C13—H13118.9H24B—C24—H24D109.5
C13—C14—C15118.95 (14)C22—C25—H25A109.5
C13—C14—C17121.41 (14)C22—C25—H25D109.5
C15—C14—C17119.61 (13)H25A—C25—H25D109.5
N2—C15—C16120.40 (14)C22—C25—H25B109.5
N2—C15—C14118.82 (14)H25A—C25—H25B109.5
C16—C15—C14120.78 (13)H25D—C25—H25B109.5
C11—C16—C15116.37 (13)C22—C26—H26D109.5
C11—C16—C22123.68 (13)C22—C26—H26A109.5
C15—C16—C22119.74 (13)H26D—C26—H26A109.5
C14—C17—C18107.56 (12)C22—C26—H26B109.5
C14—C17—C24112.67 (13)H26D—C26—H26B109.5
C18—C17—C24108.46 (14)H26A—C26—H26B109.5
C7—C1—C2—C30.6 (3)C10—C13—C14—C17178.36 (14)
C1—C2—C3—C41.0 (3)C20—N2—C15—C166.7 (2)
C2—C3—C4—C50.7 (2)C19—N2—C15—C16170.41 (16)
C6—N1—C5—C4179.25 (15)C20—N2—C15—C14173.69 (15)
C6—N1—C5—C70.07 (19)C19—N2—C15—C149.2 (2)
C3—C4—C5—N1179.17 (15)C13—C14—C15—N2177.07 (14)
C3—C4—C5—C70.1 (2)C17—C14—C15—N24.7 (2)
C5—N1—C6—C8179.91 (13)C13—C14—C15—C162.5 (2)
C5—N1—C6—S10.49 (17)C17—C14—C15—C16175.77 (13)
C7—S1—C6—N10.69 (13)O2—C11—C16—C15176.04 (12)
C7—S1—C6—C8179.71 (13)C10—C11—C16—C152.5 (2)
C2—C1—C7—C50.0 (2)O2—C11—C16—C221.4 (2)
C2—C1—C7—S1178.80 (13)C10—C11—C16—C22177.11 (14)
N1—C5—C7—C1179.56 (14)N2—C15—C16—C11175.88 (14)
C4—C5—C7—C10.2 (2)C14—C15—C16—C113.7 (2)
N1—C5—C7—S10.57 (17)N2—C15—C16—C221.0 (2)
C4—C5—C7—S1178.78 (12)C14—C15—C16—C22178.56 (13)
C6—S1—C7—C1179.54 (16)C13—C14—C17—C18144.64 (15)
C6—S1—C7—C50.66 (12)C15—C14—C17—C1837.13 (19)
N1—C6—C8—C96.1 (2)C13—C14—C17—C2425.2 (2)
S1—C6—C8—C9174.29 (12)C15—C14—C17—C24156.60 (14)
N1—C6—C8—C12172.08 (14)C13—C14—C17—C2395.14 (17)
S1—C6—C8—C127.5 (2)C15—C14—C17—C2383.09 (17)
C12—C8—C9—C103.3 (2)C14—C17—C18—C1957.26 (18)
C6—C8—C9—C10174.95 (14)C24—C17—C18—C19179.38 (14)
C8—C9—C10—C110.3 (2)C23—C17—C18—C1962.00 (18)
C8—C9—C10—C13176.38 (15)C15—N2—C19—C1812.7 (2)
C12—O2—C11—C16178.12 (13)C20—N2—C19—C18164.74 (16)
C12—O2—C11—C100.5 (2)C17—C18—C19—N246.8 (2)
C9—C10—C11—O21.6 (2)C15—N2—C20—C2118.0 (2)
C13—C10—C11—O2178.49 (13)C19—N2—C20—C21164.59 (16)
C9—C10—C11—C16176.89 (14)N2—C20—C21—C2250.0 (2)
C13—C10—C11—C160.0 (2)C11—C16—C22—C2585.78 (18)
C11—O2—C12—O1178.43 (14)C15—C16—C22—C2588.70 (17)
C11—O2—C12—C82.4 (2)C11—C16—C22—C21154.67 (14)
C9—C8—C12—O1176.73 (16)C15—C16—C22—C2130.85 (18)
C6—C8—C12—O15.0 (2)C11—C16—C22—C2637.0 (2)
C9—C8—C12—O24.2 (2)C15—C16—C22—C26148.48 (14)
C6—C8—C12—O2174.01 (13)C20—C21—C22—C1654.98 (18)
C11—C10—C13—C141.4 (2)C20—C21—C22—C2563.29 (18)
C9—C10—C13—C14175.38 (15)C20—C21—C22—C26178.78 (14)
C10—C13—C14—C150.1 (2)
Acknowledgements top

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) and funded by the Ministry of Education, Science and Technology. (2009-0072468)

references
References top

Bruker (2000). SMART and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.

Chinnakali, K., Fun, H.-K., Sriraghavan, K. & Ramakrishnan, V. T. (1999). Acta Cryst. C55, 946–948.

Gavuzzo, E., Mazza, F. & Giglio, E. (1974). Acta Cryst. B30, 1351–1357.

Kucsman, Á., Kapovits, I., Párkányi, L., Argay, Gy. & Kálmán, A. (1984). J. Mol. Struct. 125, 331–347.

Lee, S. J., Park, K.-M., Yang, K. & Kang, Y. (2009). Inorg. Chem. 48, 1030–1037.

Mellor, I. P. & Nyburg, S. C. (1971). Acta Cryst. B27, 1954–1958.

Padilla-Martínez, I. I., García-Báez, E. V., Höpfl, H. & Martínez-Martínez, F. J. I. (2003). Acta Cryst. C59, o544–o546.

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

White, W., Hudson, Z. M., Feng, X., Han, S., Lu, Z.-H. & Wang, S. (2010). Dalton Trans. pp. 892–899.