organic compounds
2-[4-(Dimethylamino)phenyl]-3,3-difluoro-3H-naphtho[1,2-e][1,3,2]oxazaborinin-2-ium-3-uide
aFaculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland, and bFaculty of Chemical Technology and Engineering, UniVersity of Technology and Life Sciences, Seminaryjna 3, 85-326 Bydgoszcz, Poland
*Correspondence e-mail: bzarychta@uni.opole.pl
In the title compound, C19H17BF2N2O, a twist about the N—C single bond is observed, making the cross conjugation not as efficient as in the case of a planar structure. The borone complex has tetrahedral geometry. In the crystal, molecules are conected by weak C—H⋯F hydrogen bonds.
Keywords: crystal structure; BODIPY dyes; flurophores.
CCDC reference: 1566411
Structure description
The organic fluorophores commonly known as BODIPY dyes are a class of compounds that are characterized by intense fluorescence, high stability and relatively small Stokes shifts. On the other hand, the difluoroborates that are hydroxy Schiff base derivatives are also important flurophores. It is known that benzannulation and the presence of a strong electron-donating group shift the maxima of absorption and emission towards the red part of the spectrum (Fabian & Hartmann, 1980). On the other hand, elongation of the molecule by a π-conjugated spacer also gives similar effect. In such a case, the presence of single bonds gives an the opportunity for rotation while the presence of the –CH=CH– moiety introduces the possibility of The last two features cause the fluorescence to be less intensive than in rigid compounds. The rigidification of the molecular skeleton may be realized by benzannulation, which is seen in the vibrationally resolved absorption spectra (Grabarz et al., 2016; Ośmiałowski et al., 2015). In any case, the geometry of molecules in their ground state is the most fundamental property that should be considered.
There is one independent molecule in the . In the crystal, there is only one classical intermolecular hydrogen bond (Table 1), which connects molecules into zigzag chains along the [101] direction (see Fig. 2). The chains are connected to each other by weak van der Waals interactions.
of the title compound. Its molecular structure is shown in Fig. 1
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The geometry of the 4-(dimethylamino)phenyl and naphthalene groups is typical (Allen, 2002). The groups are not co-planar, the dihedral angle between them being 55.12 (3)°. A twist about the N1—C12 single bond is observed, making the cross conjugation not as efficient as in the case of a planar structure. The geometry around B1 atom is tetrahedral and exhibits normal bond distances and angles (Lugo & Richards, 2010). The B—N distance [1.589 (2) Å] is notably longer than a normal B1—N1 single bond (ca 1.52 Å; Singh et al., 1986; Lugo & Richards, 2010), indicating weak bonding, and the B1—O1 bond is slightly shorter [1.460 (2) versus 1.48 Å]. This pattern of bond lengths is contrary to the model of Itoh and co-workers where the B—O bond is shorter and B—N bond is markedly longer (Itoh et al., 1998), indicating that the complex adopts a structure close to an enol tautomer.
Synthesis and crystallization
The synthesis of 2-[4-(dimethylamino)phenyl]-3,3-difluoro-3H-naphtho[1,2-e][1,3,2]oxazaborinin-2-ium-3-uide was performed by the condensation of 2-hydroxy-1-naphtaldehyde (1 g) with N,N-dimethyl-p-phenylenediamine (0.79 g) in anhydrous methanol (10 ml) as a solvent by heating the mixture at boiling point for 12 h. The resulting precipitate was re-crystallized from methanol (m.p. 168.9–171.2°C). The resulting Schiff base (0.67 g, 85%) was treated with BF3 etherate (1 ml) in chloroform (10 ml) and DIEA (1 ml). The reaction mixture was heated at boiling point for 5 h and 5 ml of Na2CO3 (saturated) was added to decompose the excess of BF3 and neutralize HF. The organic layer was separated and the remaining water layer was extracted with three portions of chloroform. The combined chloroform fractions were evaporated to dryness and next under vacuum to remove DIEA. The remaining solid was purified by flash on SiO2 with chloroform as NMR spectra were recorded using CDCl3 as a solvent. Crystals of good quality (m.p. 208–209.3°C) were obtained by slow evaporation of a CDCl3 solution in the NMR tube.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 1566411
https://doi.org/10.1107/S2414314617011415/bx4006sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617011415/bx4006Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314617011415/bx4006Isup3.cml
Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell
CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b).C19H17BF2N2O | F(000) = 704 |
Mr = 338.15 | Dx = 1.373 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 9.6529 (4) Å | Cell parameters from 10886 reflections |
b = 17.7072 (5) Å | θ = 3.3–26.0° |
c = 10.4833 (4) Å | µ = 0.10 mm−1 |
β = 114.106 (4)° | T = 100 K |
V = 1635.60 (11) Å3 | Irregular, colourless |
Z = 4 | 0.25 × 0.23 × 0.15 mm |
Oxford Diffraction Xcalibur diffractometer | 2485 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.022 |
Detector resolution: 1024 x 1024 with blocks 2 x 2 pixels mm-1 | θmax = 26.0°, θmin = 3.3° |
ω scan | h = −11→11 |
10886 measured reflections | k = −21→17 |
3196 independent reflections | l = −12→12 |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.031 | H-atom parameters constrained |
wR(F2) = 0.080 | w = 1/[σ2(Fo2) + (0.0519P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.98 | (Δ/σ)max = 0.001 |
3196 reflections | Δρmax = 0.18 e Å−3 |
228 parameters | Δρmin = −0.20 e Å−3 |
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. All H atoms were found in a difference map but set to idealized positions and treated as riding with CAr—H = 0.93 Å and Uiso(H) = 1.2Ueq(C) for C—H and with C—H3 = 0.96 Å and Uiso(H) = 1.5Ueq(C). |
x | y | z | Uiso*/Ueq | ||
O1 | 0.67086 (9) | 0.34092 (4) | 0.45068 (8) | 0.0198 (2) | |
F1 | 0.87188 (8) | 0.37674 (4) | 0.65386 (7) | 0.0293 (2) | |
F2 | 0.63047 (8) | 0.39784 (4) | 0.63418 (7) | 0.0302 (2) | |
B1 | 0.72560 (16) | 0.39555 (7) | 0.56491 (14) | 0.0196 (3) | |
N1 | 0.72551 (10) | 0.47697 (5) | 0.50108 (9) | 0.0161 (2) | |
N2 | 1.08863 (11) | 0.71216 (5) | 0.83259 (10) | 0.0235 (2) | |
C1 | 0.56665 (13) | 0.35922 (6) | 0.32362 (12) | 0.0175 (3) | |
C2 | 0.48595 (13) | 0.30025 (6) | 0.23360 (13) | 0.0210 (3) | |
H2 | 0.5040 | 0.2504 | 0.2635 | 0.025* | |
C3 | 0.38129 (13) | 0.31661 (7) | 0.10243 (12) | 0.0208 (3) | |
H3 | 0.3284 | 0.2773 | 0.0441 | 0.025* | |
C4 | 0.35069 (13) | 0.39207 (6) | 0.05228 (12) | 0.0180 (3) | |
C5 | 0.23941 (13) | 0.40864 (7) | −0.08298 (12) | 0.0212 (3) | |
H5 | 0.1861 | 0.3694 | −0.1413 | 0.025* | |
C6 | 0.20910 (13) | 0.48159 (7) | −0.12919 (12) | 0.0216 (3) | |
H6 | 0.1362 | 0.4917 | −0.2184 | 0.026* | |
C7 | 0.28848 (13) | 0.54113 (7) | −0.04138 (12) | 0.0199 (3) | |
H7 | 0.2682 | 0.5906 | −0.0732 | 0.024* | |
C8 | 0.39571 (12) | 0.52711 (6) | 0.09082 (12) | 0.0177 (3) | |
H8 | 0.4461 | 0.5673 | 0.1480 | 0.021* | |
C9 | 0.43083 (12) | 0.45235 (6) | 0.14152 (12) | 0.0160 (2) | |
C10 | 0.54181 (12) | 0.43441 (6) | 0.27937 (11) | 0.0157 (2) | |
C11 | 0.63361 (12) | 0.49104 (6) | 0.37190 (12) | 0.0164 (3) | |
H11 | 0.6278 | 0.5402 | 0.3388 | 0.020* | |
C12 | 0.82088 (12) | 0.53630 (6) | 0.58513 (11) | 0.0164 (3) | |
C13 | 0.89989 (12) | 0.58379 (6) | 0.53311 (11) | 0.0178 (3) | |
H13 | 0.8943 | 0.5761 | 0.4434 | 0.021* | |
C14 | 0.98708 (13) | 0.64254 (6) | 0.61356 (12) | 0.0193 (3) | |
H14 | 1.0391 | 0.6739 | 0.5769 | 0.023* | |
C15 | 0.99802 (13) | 0.65550 (6) | 0.75010 (12) | 0.0180 (3) | |
C16 | 0.91852 (13) | 0.60575 (7) | 0.80092 (12) | 0.0202 (3) | |
H16 | 0.9238 | 0.6126 | 0.8907 | 0.024* | |
C17 | 0.83328 (13) | 0.54721 (6) | 0.72075 (12) | 0.0187 (3) | |
H17 | 0.7835 | 0.5146 | 0.7576 | 0.022* | |
C18 | 1.14248 (15) | 0.77096 (7) | 0.76815 (13) | 0.0293 (3) | |
H18A | 1.2052 | 0.7490 | 0.7267 | 0.044* | |
H18B | 1.2005 | 0.8071 | 0.8378 | 0.044* | |
H18C | 1.0574 | 0.7958 | 0.6972 | 0.044* | |
C19 | 1.08519 (15) | 0.72867 (7) | 0.96778 (13) | 0.0299 (3) | |
H19A | 0.9841 | 0.7429 | 0.9542 | 0.045* | |
H19B | 1.1537 | 0.7694 | 1.0119 | 0.045* | |
H19C | 1.1154 | 0.6846 | 1.0261 | 0.045* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0213 (4) | 0.0160 (4) | 0.0181 (4) | 0.0008 (3) | 0.0041 (4) | 0.0012 (3) |
F1 | 0.0289 (4) | 0.0209 (4) | 0.0242 (4) | 0.0021 (3) | −0.0032 (3) | 0.0030 (3) |
F2 | 0.0444 (5) | 0.0246 (4) | 0.0299 (4) | −0.0075 (3) | 0.0235 (4) | −0.0028 (3) |
B1 | 0.0229 (7) | 0.0162 (7) | 0.0172 (7) | −0.0006 (5) | 0.0056 (6) | 0.0008 (5) |
N1 | 0.0144 (5) | 0.0162 (5) | 0.0161 (5) | 0.0000 (4) | 0.0046 (4) | −0.0010 (4) |
N2 | 0.0272 (6) | 0.0206 (5) | 0.0202 (6) | −0.0052 (4) | 0.0069 (5) | −0.0050 (4) |
C1 | 0.0160 (6) | 0.0193 (6) | 0.0177 (6) | 0.0008 (5) | 0.0074 (5) | 0.0012 (5) |
C2 | 0.0237 (7) | 0.0148 (6) | 0.0244 (7) | −0.0006 (5) | 0.0098 (5) | −0.0009 (5) |
C3 | 0.0202 (6) | 0.0193 (6) | 0.0223 (6) | −0.0044 (5) | 0.0080 (5) | −0.0066 (5) |
C4 | 0.0142 (6) | 0.0215 (6) | 0.0191 (6) | −0.0017 (5) | 0.0074 (5) | −0.0037 (5) |
C5 | 0.0165 (6) | 0.0252 (6) | 0.0201 (6) | −0.0021 (5) | 0.0057 (5) | −0.0068 (5) |
C6 | 0.0163 (6) | 0.0300 (7) | 0.0158 (6) | 0.0036 (5) | 0.0038 (5) | −0.0013 (5) |
C7 | 0.0194 (6) | 0.0219 (6) | 0.0191 (6) | 0.0037 (5) | 0.0085 (5) | 0.0016 (5) |
C8 | 0.0153 (6) | 0.0185 (6) | 0.0180 (6) | −0.0012 (5) | 0.0055 (5) | −0.0026 (5) |
C9 | 0.0131 (6) | 0.0195 (6) | 0.0169 (6) | −0.0007 (5) | 0.0074 (5) | −0.0021 (5) |
C10 | 0.0145 (6) | 0.0166 (6) | 0.0163 (6) | −0.0004 (5) | 0.0067 (5) | −0.0007 (5) |
C11 | 0.0150 (6) | 0.0156 (6) | 0.0178 (6) | 0.0019 (4) | 0.0059 (5) | 0.0015 (5) |
C12 | 0.0129 (6) | 0.0157 (6) | 0.0173 (6) | 0.0019 (4) | 0.0029 (5) | −0.0001 (5) |
C13 | 0.0180 (6) | 0.0192 (6) | 0.0130 (6) | 0.0028 (5) | 0.0030 (5) | 0.0010 (5) |
C14 | 0.0190 (6) | 0.0173 (6) | 0.0200 (6) | −0.0004 (5) | 0.0063 (5) | 0.0023 (5) |
C15 | 0.0148 (6) | 0.0162 (6) | 0.0189 (6) | 0.0027 (4) | 0.0026 (5) | −0.0011 (5) |
C16 | 0.0175 (6) | 0.0259 (7) | 0.0170 (6) | 0.0022 (5) | 0.0068 (5) | −0.0023 (5) |
C17 | 0.0159 (6) | 0.0206 (6) | 0.0199 (6) | 0.0003 (5) | 0.0077 (5) | 0.0005 (5) |
C18 | 0.0327 (8) | 0.0199 (7) | 0.0294 (7) | −0.0066 (6) | 0.0067 (6) | −0.0041 (5) |
C19 | 0.0323 (8) | 0.0283 (7) | 0.0269 (7) | −0.0050 (6) | 0.0100 (6) | −0.0124 (6) |
O1—C1 | 1.3404 (14) | C7—H7 | 0.9300 |
O1—B1 | 1.4602 (15) | C8—C9 | 1.4152 (16) |
F1—B1 | 1.3779 (15) | C8—H8 | 0.9300 |
F2—B1 | 1.3846 (15) | C9—C10 | 1.4396 (15) |
B1—N1 | 1.5892 (16) | C10—C11 | 1.4246 (15) |
N1—C11 | 1.3045 (14) | C11—H11 | 0.9300 |
N1—C12 | 1.4369 (14) | C12—C13 | 1.3878 (16) |
N2—C15 | 1.3789 (14) | C12—C17 | 1.3907 (15) |
N2—C18 | 1.4483 (15) | C13—C14 | 1.3863 (16) |
N2—C19 | 1.4607 (15) | C13—H13 | 0.9300 |
C1—C10 | 1.3981 (15) | C14—C15 | 1.4105 (16) |
C1—C2 | 1.4096 (16) | C14—H14 | 0.9300 |
C2—C3 | 1.3641 (17) | C15—C16 | 1.4081 (16) |
C2—H2 | 0.9300 | C16—C17 | 1.3759 (16) |
C3—C4 | 1.4221 (16) | C16—H16 | 0.9300 |
C3—H3 | 0.9300 | C17—H17 | 0.9300 |
C4—C5 | 1.4165 (16) | C18—H18A | 0.9600 |
C4—C9 | 1.4218 (16) | C18—H18B | 0.9600 |
C5—C6 | 1.3685 (17) | C18—H18C | 0.9600 |
C5—H5 | 0.9300 | C19—H19A | 0.9600 |
C6—C7 | 1.4036 (16) | C19—H19B | 0.9600 |
C6—H6 | 0.9300 | C19—H19C | 0.9600 |
C7—C8 | 1.3718 (16) | ||
C1—O1—B1 | 121.89 (9) | C8—C9—C10 | 123.32 (10) |
F1—B1—F2 | 111.59 (10) | C4—C9—C10 | 118.47 (10) |
F1—B1—O1 | 108.81 (10) | C1—C10—C11 | 118.02 (10) |
F2—B1—O1 | 110.74 (10) | C1—C10—C9 | 119.98 (10) |
F1—B1—N1 | 109.17 (10) | C11—C10—C9 | 121.95 (10) |
F2—B1—N1 | 107.93 (9) | N1—C11—C10 | 122.86 (10) |
O1—B1—N1 | 108.53 (9) | N1—C11—H11 | 118.6 |
C11—N1—C12 | 119.38 (9) | C10—C11—H11 | 118.6 |
C11—N1—B1 | 119.58 (9) | C13—C12—C17 | 119.07 (10) |
C12—N1—B1 | 121.00 (9) | C13—C12—N1 | 121.29 (10) |
C15—N2—C18 | 119.15 (10) | C17—C12—N1 | 119.64 (10) |
C15—N2—C19 | 119.61 (10) | C14—C13—C12 | 120.68 (10) |
C18—N2—C19 | 117.60 (9) | C14—C13—H13 | 119.7 |
O1—C1—C10 | 121.15 (10) | C12—C13—H13 | 119.7 |
O1—C1—C2 | 118.13 (10) | C13—C14—C15 | 120.98 (11) |
C10—C1—C2 | 120.69 (11) | C13—C14—H14 | 119.5 |
C3—C2—C1 | 119.80 (11) | C15—C14—H14 | 119.5 |
C3—C2—H2 | 120.1 | N2—C15—C16 | 121.47 (11) |
C1—C2—H2 | 120.1 | N2—C15—C14 | 121.35 (10) |
C2—C3—C4 | 121.91 (11) | C16—C15—C14 | 117.11 (10) |
C2—C3—H3 | 119.0 | C17—C16—C15 | 121.51 (11) |
C4—C3—H3 | 119.0 | C17—C16—H16 | 119.2 |
C5—C4—C9 | 119.31 (11) | C15—C16—H16 | 119.2 |
C5—C4—C3 | 121.52 (10) | C16—C17—C12 | 120.63 (11) |
C9—C4—C3 | 119.15 (11) | C16—C17—H17 | 119.7 |
C6—C5—C4 | 120.99 (11) | C12—C17—H17 | 119.7 |
C6—C5—H5 | 119.5 | N2—C18—H18A | 109.5 |
C4—C5—H5 | 119.5 | N2—C18—H18B | 109.5 |
C5—C6—C7 | 119.76 (11) | H18A—C18—H18B | 109.5 |
C5—C6—H6 | 120.1 | N2—C18—H18C | 109.5 |
C7—C6—H6 | 120.1 | H18A—C18—H18C | 109.5 |
C8—C7—C6 | 120.74 (11) | H18B—C18—H18C | 109.5 |
C8—C7—H7 | 119.6 | N2—C19—H19A | 109.5 |
C6—C7—H7 | 119.6 | N2—C19—H19B | 109.5 |
C7—C8—C9 | 120.99 (10) | H19A—C19—H19B | 109.5 |
C7—C8—H8 | 119.5 | N2—C19—H19C | 109.5 |
C9—C8—H8 | 119.5 | H19A—C19—H19C | 109.5 |
C8—C9—C4 | 118.20 (10) | H19B—C19—H19C | 109.5 |
C1—O1—B1—F1 | −151.50 (10) | O1—C1—C10—C9 | 179.02 (10) |
C1—O1—B1—F2 | 85.50 (13) | C2—C1—C10—C9 | 1.17 (16) |
C1—O1—B1—N1 | −32.81 (14) | C8—C9—C10—C1 | 177.88 (10) |
F1—B1—N1—C11 | 143.57 (10) | C4—C9—C10—C1 | −1.18 (16) |
F2—B1—N1—C11 | −94.96 (12) | C8—C9—C10—C11 | −4.96 (16) |
O1—B1—N1—C11 | 25.11 (14) | C4—C9—C10—C11 | 175.99 (10) |
F1—B1—N1—C12 | −38.90 (14) | C12—N1—C11—C10 | 176.32 (10) |
F2—B1—N1—C12 | 82.57 (12) | B1—N1—C11—C10 | −6.11 (16) |
O1—B1—N1—C12 | −157.36 (9) | C1—C10—C11—N1 | −8.74 (16) |
B1—O1—C1—C10 | 21.42 (16) | C9—C10—C11—N1 | 174.03 (10) |
B1—O1—C1—C2 | −160.67 (11) | C11—N1—C12—C13 | −44.76 (15) |
O1—C1—C2—C3 | −178.63 (10) | B1—N1—C12—C13 | 137.71 (11) |
C10—C1—C2—C3 | −0.71 (17) | C11—N1—C12—C17 | 134.44 (11) |
C1—C2—C3—C4 | 0.29 (18) | B1—N1—C12—C17 | −43.09 (15) |
C2—C3—C4—C5 | −178.58 (11) | C17—C12—C13—C14 | −1.59 (16) |
C2—C3—C4—C9 | −0.32 (17) | N1—C12—C13—C14 | 177.62 (10) |
C9—C4—C5—C6 | 0.60 (17) | C12—C13—C14—C15 | 0.10 (17) |
C3—C4—C5—C6 | 178.85 (11) | C18—N2—C15—C16 | −167.37 (11) |
C4—C5—C6—C7 | −0.39 (17) | C19—N2—C15—C16 | −9.36 (17) |
C5—C6—C7—C8 | −0.38 (17) | C18—N2—C15—C14 | 15.88 (16) |
C6—C7—C8—C9 | 0.94 (17) | C19—N2—C15—C14 | 173.89 (11) |
C7—C8—C9—C4 | −0.71 (16) | C13—C14—C15—N2 | 177.72 (10) |
C7—C8—C9—C10 | −179.77 (11) | C13—C14—C15—C16 | 0.83 (16) |
C5—C4—C9—C8 | −0.05 (15) | N2—C15—C16—C17 | −177.17 (11) |
C3—C4—C9—C8 | −178.35 (10) | C14—C15—C16—C17 | −0.28 (17) |
C5—C4—C9—C10 | 179.05 (10) | C15—C16—C17—C12 | −1.21 (17) |
C3—C4—C9—C10 | 0.76 (15) | C13—C12—C17—C16 | 2.14 (17) |
O1—C1—C10—C11 | 1.74 (16) | N1—C12—C17—C16 | −177.08 (10) |
C2—C1—C10—C11 | −176.11 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···F1i | 0.93 | 2.61 | 3.3138 (13) | 133 |
C17—H17···F2 | 0.93 | 2.56 | 3.1938 (13) | 125 |
Symmetry code: (i) x−1/2, −y+1/2, z−1/2. |
References
Allen, F. H. (2002). Acta Cryst. B58, 380–388. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Fabian, J. & Hartmann, H. (1980). Light Absorption of Organic Colorants – Theoretical Treatment and Empirical Rules. Berlin, Heidelberg, New York: Springer-Verlag. Google Scholar
Grabarz, A. M., Laurent, A. D., Jędrzejewska, B., Zakrzewska, A., Jacquemin, D. & Ośmiałowski, B. (2016). J. Org. Chem. 81, 2280–2292. Web of Science CrossRef CAS PubMed Google Scholar
Itoh, K., Fujimoto, M. & Hashimoto, M. (1998). Acta Cryst. C54, 1324–1327. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Lugo née Gushwa, A. F. & Richards, A. F. (2010). Eur. J. Inorg. Chem. pp. 2025–2035. Google Scholar
Oxford Diffraction (2008). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England. Google Scholar
Ośmiałowski, B., Zakrzewska, A., Jędrzejewska, B., Grabarz, A., Zaleśny, R., Bartkowiak, W. & Kolehmainen, E. (2015). J. Org. Chem. 80, 2072–2080. Web of Science PubMed Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Singh, Y. P., Rupani, P., Singh, A., Rai, A. K., Mehrotra, R. C., Rogers, R. D. & Atwood, J. L. (1986). Inorg. Chem. 25, 3076–3081. CSD CrossRef CAS Web of Science Google Scholar
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