organic compounds
(Biphenyl-2,2′-diyl)di-tert-butylphosphonium trifluoromethanesulfonate
aDepartment of Chemistry, University of Johannesburg (APK Campus), PO Box 524, Auckland Park, Johannesburg, 2006, South Africa
*Correspondence e-mail: mullera@uj.ac.za
To aid in the elucidation of catalytic 20H26P+·CF3SO3−. Selected geometrical parameters include P—biphenyl (av.) = 1.801 (3) Å and P—t-Bu (av.) = 1.858 (3) Å, and significant distortion of the tetrahedral P-atom environment with biphenyl—P—biphenyl = 93.93 (13)° and t-Bu—P—t-Bu = 118.82 (14)°. In the crystal, weak C—H⋯O interactions lead to channels along the c axis that are occupied by CF3SO3− anions.
of palladacycles, we found that reaction of trifluoromethanesulfonic acid with a phosphapalladacycle resulted in elimination of the palladium and formation of the title phospholium salt, CRelated literature
For background to catalytic studies on palladacycles, see: Herrman et al. (2003); Beletskaya & Cheprakov (2004); Omondi et al. (2011); Williams et al. (2008); d'Orlye & Jutland (2005). For a description of the Cambridge Structural Database, see: Allen (2002).
Experimental
Crystal data
|
Data collection: SMART-NT (Bruker, 1998); cell SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus and XPREP (Bruker, 2008); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 2012).
Supporting information
https://doi.org/10.1107/S1600536812049045/aa2079sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812049045/aa2079Isup2.hkl
Trifluorometanesulfonic acid (150 mg, 1 mmol) in 5 ml me thanol was added dropwise to a stirred solution of (acetato-κ2O,O')[2'-(di-tert- butylphosphanyl)-1,1'-biphenyl-κ2P,C2]palladium (462 mg, 1 mmol) in dichloromethane (30 ml) at room temperature under argon. The solution changed from colourless to deep purple and then to dark brown over a period of 10 min. After several hours at room temperature a fine precipitate of palladium black started to form. After 24 h the reaction mixture was filtered through celite to remove the palladium. The solvent was removed in vacuo and the residue distributed between water (15 ml) and ether (15 ml). The aqueous phase was extracted with dichloromethane (3 x 30 ml). The combined extract furnished crystalline (413 mg, 82%) on removal of the solvent in vacuo. Good crystals (mp. 157 – 159 °C) was obtained by diffusion of the vapours of ether into a solution in dichloromethane. Analytical data: 1H-NMR: δ 1.45 (18H, d, J = 17 Hz), 7.68 (2H, dt, J = 2.5 and 7.5 Hz), 7.85 (2H, t, J = 7.8 Hz), 7.99 (2H, t, J = 7.8 Hz), and 8.64 (2H, dd, J = 2.5 and 7.8 Hz) 13C{H}-NMR: δ 26.74 (s), 36.42 (d, J = 42 Hz), 118.72 (d, J = 101 Hz), 123.58 (d, J = 12.3 Hz), 130.90 (d, J = 14.0 Hz), 131.90 (d, J = 14.0 Hz), 131.67 (d, J = 11.4 Hz), 135.95 (d, J = 2.7 Hz), 144.97 (d, J = 17.4 Hz) 31P-NMR: δ 51.24
All hydrogen atoms for methyl and aromatic H atoms were positioned in geometrically idealized positions with C—H = 0.96 Å and 0.93 Å respectively. Aromatic hydrogen atoms were allowed to ride on their parent atoms with Uiso(H) = 1.2Ueq, and for methyl hydrogen atoms Uiso(H) = 1.5Ueq was utilized. The initial positions of methyl hydrogen atoms were located from a Fourier difference map and refined as fixed rotor. The
refined to 0.05 (11).The introduction of a cyclopalladated compound as a robust catalyst (Herrman et al., 2003) for Heck and cross-coupling reactions resulted in the design of structurally related palladacycles, phosphapalladacycles in particular (Beletskaya & Cheprakov, 2004). However, growing evidence suggests that palladacycles are disassembled during the pre-activation stage to yield low ligated Pd0 species as the actual catalyst (d'Orlye & Jutland, 2005). This is further exemplified by our finding that the use of palladacycle (II in Fig. 1), an effective amination catalyst (Beletskaya & Cheprakov, 2004), as a source of palladium together with triphenylphosphine and a strong acid provided an extremely active catalytic system for the hydromethoxylation of
(Omondi et al., 2011 and Williams et al., 2008). In the reaction medium compound II (Fig. 1) was rapidly converted into tetrakistriphenylphosphinepalladium(0) which acted as the actual catalyst. The facile formation of Pd0 resulted from acid catalyzed elimination from the palladacycle. This treatment of II with ten equivalents of trifluoromethanesulfonic acid at room temperature resulted in the formation of colloidal palladium and the title compound (I in Fig. 1), the structure of which was confirmed by single-crystal X-ray crystallography.The title compound I (Fig. 2 and Scheme 1) is a salt consisting of phospholium cations and trifluoromethanesulfonate anions. All ions lie on general positions in the
with no discernible differences in the bond distances of the of the phosphorus environment. The bond angles at the phosphorus center shows significant deviations from the expected 109.5° for the tetrahedral shape with biphenyl—P—biphenyl = 93.93 (13)° and t-Bu—P—t-Bu = 118.82 (14)°. These deviations can be ascribed to the somewhat strained 5-membered cyclisation of the dibenzo fragment to form the phospholium ring. This pinching effect in turn allows for more space for the bulky tertiary butyl groups positioned above and below the plane formed by the tricyclic phospholium conjugate and hence the observed t-Bu—P—t-Bu angle. The tricyclic phospholium conjugate marginally deviates from planarity (C1—C6—C7—C12 = 1.9 (4)°), and would have been the primary route to alleviate stress from the pinching effect. Data extracted from the Cambridge Structural Database (Allen, 2002) for the torsion angle between the planes shows a mean value of 1.72° (126 observations). The general trend seems to be that substituents opposite the phospholium cycle forces it to be planar. The of the tertiary butyls are due to several weak C—H···O interactions observed between ions (see Table 1).For background to catalytic studies on palladacycles, see: Herrman et al. (2003); Beletskaya & Cheprakov (2004); Omondi et al. (2011); Williams et al. (2008); d'Orlye & Jutland (2005). For a description of the Cambridge Structural Database, see: Allen (2002).
Data collection: SMART-NT (Bruker, 1998); cell
SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus and XPREP (Bruker, 2008); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 2012).C20H26P+·CF3O3S− | Dx = 1.34 Mg m−3 |
Mr = 446.45 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, P41212 | Cell parameters from 3572 reflections |
Hall symbol: P 4abw 2nw | θ = 2.5–21.9° |
a = 12.1339 (10) Å | µ = 0.26 mm−1 |
c = 30.057 (2) Å | T = 293 K |
V = 4425.4 (6) Å3 | Prism, yellow |
Z = 8 | 0.4 × 0.26 × 0.2 mm |
F(000) = 1872 |
Bruker SMART 1K CCD diffractometer | 3241 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.101 |
π scans | θmax = 28.4°, θmin = 1.8° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −13→16 |
Tmin = 0.902, Tmax = 0.949 | k = −11→16 |
25275 measured reflections | l = −39→28 |
5502 independent reflections |
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)] = 0.054 | H-atom parameters constrained |
wR(F2) = 0.117 | w = 1/[σ2(Fo2) + (0.0519P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.99 | (Δ/σ)max = 0.001 |
5502 reflections | Δρmax = 0.17 e Å−3 |
268 parameters | Δρmin = −0.25 e Å−3 |
0 restraints | Absolute structure: Flack (1983), 2283 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.05 (11) |
C20H26P+·CF3O3S− | Z = 8 |
Mr = 446.45 | Mo Kα radiation |
Tetragonal, P41212 | µ = 0.26 mm−1 |
a = 12.1339 (10) Å | T = 293 K |
c = 30.057 (2) Å | 0.4 × 0.26 × 0.2 mm |
V = 4425.4 (6) Å3 |
Bruker SMART 1K CCD diffractometer | 5502 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 3241 reflections with I > 2σ(I) |
Tmin = 0.902, Tmax = 0.949 | Rint = 0.101 |
25275 measured reflections |
R[F2 > 2σ(F2)] = 0.054 | H-atom parameters constrained |
wR(F2) = 0.117 | Δρmax = 0.17 e Å−3 |
S = 0.99 | Δρmin = −0.25 e Å−3 |
5502 reflections | Absolute structure: Flack (1983), 2283 Friedel pairs |
268 parameters | Absolute structure parameter: 0.05 (11) |
0 restraints |
Experimental. The intensity data was collected on a Bruker SMART 1 K CCD diffractometer using an exposure time of 20 s/frame. A total of 984 frames were collected with a frame width of 0.3° covering up to θ = 28.37° with 99.3% completeness accomplished. |
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. |
x | y | z | Uiso*/Ueq | ||
P1 | 0.60082 (6) | 0.44749 (6) | 0.87672 (2) | 0.03329 (18) | |
C1 | 0.4783 (2) | 0.4567 (2) | 0.84292 (9) | 0.0370 (7) | |
C2 | 0.4328 (2) | 0.3813 (3) | 0.81337 (9) | 0.0454 (8) | |
H2 | 0.4651 | 0.3126 | 0.8092 | 0.054* | |
C3 | 0.3384 (3) | 0.4104 (3) | 0.79028 (11) | 0.0576 (9) | |
H3 | 0.3082 | 0.3616 | 0.7698 | 0.069* | |
C4 | 0.2892 (3) | 0.5108 (3) | 0.79748 (13) | 0.0744 (12) | |
H4 | 0.2255 | 0.5289 | 0.7819 | 0.089* | |
C5 | 0.3324 (3) | 0.5852 (3) | 0.82750 (13) | 0.0746 (12) | |
H5 | 0.2979 | 0.6525 | 0.8322 | 0.09* | |
C6 | 0.4280 (2) | 0.5587 (3) | 0.85057 (10) | 0.0472 (8) | |
C7 | 0.4846 (2) | 0.6282 (2) | 0.88434 (10) | 0.0450 (7) | |
C8 | 0.4517 (3) | 0.7307 (3) | 0.89949 (13) | 0.0692 (11) | |
H8 | 0.3888 | 0.7639 | 0.888 | 0.083* | |
C9 | 0.5129 (4) | 0.7833 (3) | 0.93185 (12) | 0.0687 (11) | |
H9 | 0.4896 | 0.8516 | 0.9424 | 0.082* | |
C10 | 0.6074 (3) | 0.7372 (3) | 0.94885 (10) | 0.0536 (9) | |
H10 | 0.6475 | 0.774 | 0.9706 | 0.064* | |
C11 | 0.6428 (3) | 0.6358 (3) | 0.93346 (9) | 0.0427 (8) | |
H11 | 0.7076 | 0.6048 | 0.9443 | 0.051* | |
C12 | 0.5808 (2) | 0.5806 (2) | 0.90172 (9) | 0.0359 (7) | |
C13 | 0.7242 (2) | 0.4477 (3) | 0.83999 (9) | 0.0402 (7) | |
C14 | 0.7210 (3) | 0.3492 (3) | 0.80819 (11) | 0.0714 (12) | |
H14A | 0.7818 | 0.3538 | 0.7878 | 0.107* | |
H14B | 0.653 | 0.3501 | 0.7918 | 0.107* | |
H14C | 0.7262 | 0.2821 | 0.8249 | 0.107* | |
C15 | 0.8297 (3) | 0.4475 (3) | 0.86695 (11) | 0.0643 (10) | |
H15A | 0.8327 | 0.382 | 0.8848 | 0.096* | |
H15B | 0.8314 | 0.5112 | 0.8859 | 0.096* | |
H15C | 0.8919 | 0.4491 | 0.8472 | 0.096* | |
C16 | 0.7161 (3) | 0.5544 (3) | 0.81278 (12) | 0.0724 (11) | |
H16A | 0.7235 | 0.6167 | 0.8322 | 0.109* | |
H16B | 0.6458 | 0.5573 | 0.7981 | 0.109* | |
H16C | 0.7738 | 0.5558 | 0.7909 | 0.109* | |
C17 | 0.5876 (3) | 0.3380 (2) | 0.91950 (10) | 0.0441 (8) | |
C18 | 0.6709 (3) | 0.3567 (3) | 0.95735 (11) | 0.0679 (11) | |
H18A | 0.6629 | 0.2996 | 0.9792 | 0.102* | |
H18B | 0.6574 | 0.4271 | 0.9709 | 0.102* | |
H18C | 0.7444 | 0.3552 | 0.9455 | 0.102* | |
C19 | 0.6031 (3) | 0.2239 (3) | 0.89885 (11) | 0.0651 (10) | |
H19A | 0.5876 | 0.1684 | 0.9207 | 0.098* | |
H19B | 0.6777 | 0.2162 | 0.8887 | 0.098* | |
H19C | 0.5536 | 0.2156 | 0.8742 | 0.098* | |
C20 | 0.4700 (3) | 0.3478 (3) | 0.93813 (13) | 0.0797 (13) | |
H20A | 0.4177 | 0.3361 | 0.9146 | 0.12* | |
H20B | 0.4596 | 0.42 | 0.9505 | 0.12* | |
H20C | 0.4592 | 0.2934 | 0.9609 | 0.12* | |
C21 | 0.1201 (3) | 0.5421 (4) | 0.93747 (13) | 0.0681 (11) | |
S1 | 0.01008 (7) | 0.49559 (7) | 0.97325 (2) | 0.0494 (2) | |
O1 | −0.0109 (2) | 0.3861 (2) | 0.95856 (8) | 0.0773 (8) | |
O2 | 0.0560 (2) | 0.5059 (2) | 1.01687 (8) | 0.0780 (8) | |
O3 | −0.0772 (2) | 0.5722 (2) | 0.96379 (8) | 0.0762 (8) | |
F1 | 0.0927 (2) | 0.5358 (2) | 0.89479 (7) | 0.0956 (8) | |
F2 | 0.2088 (2) | 0.4800 (3) | 0.94266 (10) | 0.1323 (12) | |
F3 | 0.1493 (2) | 0.6442 (2) | 0.94525 (9) | 0.1194 (10) |
U11 | U22 | U33 | U12 | U13 | U23 | |
P1 | 0.0327 (4) | 0.0315 (4) | 0.0357 (4) | 0.0012 (3) | −0.0020 (3) | −0.0017 (3) |
C1 | 0.0316 (17) | 0.0394 (17) | 0.0402 (17) | −0.0015 (13) | −0.0040 (12) | −0.0074 (13) |
C2 | 0.0408 (19) | 0.046 (2) | 0.0499 (18) | −0.0048 (14) | −0.0006 (14) | −0.0101 (14) |
C3 | 0.043 (2) | 0.073 (3) | 0.057 (2) | −0.0074 (19) | −0.0131 (16) | −0.0140 (19) |
C4 | 0.054 (2) | 0.082 (3) | 0.087 (3) | 0.016 (2) | −0.036 (2) | −0.019 (2) |
C5 | 0.059 (3) | 0.068 (3) | 0.097 (3) | 0.025 (2) | −0.031 (2) | −0.023 (2) |
C6 | 0.0405 (19) | 0.0486 (19) | 0.0527 (19) | 0.0085 (15) | −0.0091 (14) | −0.0083 (16) |
C7 | 0.0429 (19) | 0.0394 (18) | 0.0527 (19) | 0.0092 (14) | −0.0024 (14) | −0.0075 (14) |
C8 | 0.076 (3) | 0.052 (2) | 0.080 (3) | 0.028 (2) | −0.016 (2) | −0.0170 (19) |
C9 | 0.089 (3) | 0.043 (2) | 0.074 (3) | 0.015 (2) | −0.001 (2) | −0.0187 (18) |
C10 | 0.074 (3) | 0.044 (2) | 0.0424 (19) | −0.0093 (19) | 0.0009 (18) | −0.0068 (15) |
C11 | 0.0457 (19) | 0.0417 (19) | 0.0406 (18) | −0.0064 (15) | −0.0008 (14) | −0.0039 (14) |
C12 | 0.0392 (18) | 0.0305 (17) | 0.0379 (16) | −0.0011 (12) | 0.0000 (13) | −0.0047 (12) |
C13 | 0.0338 (17) | 0.0500 (19) | 0.0366 (17) | 0.0014 (14) | −0.0006 (13) | −0.0024 (15) |
C14 | 0.062 (3) | 0.091 (3) | 0.061 (2) | 0.004 (2) | 0.0162 (19) | −0.030 (2) |
C15 | 0.038 (2) | 0.100 (3) | 0.055 (2) | 0.0045 (19) | −0.0035 (16) | −0.007 (2) |
C16 | 0.059 (2) | 0.084 (3) | 0.075 (3) | 0.001 (2) | 0.0156 (19) | 0.034 (2) |
C17 | 0.048 (2) | 0.0409 (19) | 0.0433 (18) | −0.0060 (14) | 0.0026 (15) | 0.0063 (13) |
C18 | 0.088 (3) | 0.061 (2) | 0.055 (2) | −0.008 (2) | −0.019 (2) | 0.0175 (18) |
C19 | 0.090 (3) | 0.042 (2) | 0.063 (2) | −0.0063 (19) | −0.011 (2) | 0.0065 (17) |
C20 | 0.069 (3) | 0.092 (3) | 0.078 (3) | −0.004 (2) | 0.025 (2) | 0.026 (2) |
C21 | 0.065 (3) | 0.072 (3) | 0.068 (3) | −0.002 (2) | −0.002 (2) | −0.003 (2) |
S1 | 0.0554 (5) | 0.0515 (5) | 0.0412 (4) | −0.0037 (4) | −0.0034 (4) | −0.0056 (4) |
O1 | 0.103 (2) | 0.0526 (16) | 0.0761 (17) | −0.0131 (15) | −0.0052 (16) | −0.0034 (13) |
O2 | 0.0889 (19) | 0.102 (2) | 0.0427 (14) | −0.0036 (16) | −0.0149 (12) | −0.0077 (13) |
O3 | 0.0609 (18) | 0.089 (2) | 0.0783 (16) | 0.0226 (14) | −0.0057 (13) | −0.0149 (15) |
F1 | 0.109 (2) | 0.125 (2) | 0.0528 (13) | −0.0194 (16) | 0.0148 (12) | 0.0069 (13) |
F2 | 0.0551 (16) | 0.197 (4) | 0.145 (2) | 0.036 (2) | 0.0137 (16) | −0.001 (2) |
F3 | 0.139 (3) | 0.092 (2) | 0.128 (2) | −0.0655 (18) | 0.0139 (19) | −0.0078 (16) |
P1—C12 | 1.798 (3) | C14—H14A | 0.96 |
P1—C1 | 1.804 (3) | C14—H14B | 0.96 |
P1—C17 | 1.856 (3) | C14—H14C | 0.96 |
P1—C13 | 1.860 (3) | C15—H15A | 0.96 |
C1—C2 | 1.389 (4) | C15—H15B | 0.96 |
C1—C6 | 1.400 (4) | C15—H15C | 0.96 |
C2—C3 | 1.384 (4) | C16—H16A | 0.96 |
C2—H2 | 0.93 | C16—H16B | 0.96 |
C3—C4 | 1.374 (5) | C16—H16C | 0.96 |
C3—H3 | 0.93 | C17—C19 | 1.529 (4) |
C4—C5 | 1.380 (5) | C17—C20 | 1.538 (5) |
C4—H4 | 0.93 | C17—C18 | 1.538 (4) |
C5—C6 | 1.388 (4) | C18—H18A | 0.96 |
C5—H5 | 0.93 | C18—H18B | 0.96 |
C6—C7 | 1.487 (4) | C18—H18C | 0.96 |
C7—C8 | 1.383 (4) | C19—H19A | 0.96 |
C7—C12 | 1.403 (4) | C19—H19B | 0.96 |
C8—C9 | 1.380 (5) | C19—H19C | 0.96 |
C8—H8 | 0.93 | C20—H20A | 0.96 |
C9—C10 | 1.376 (5) | C20—H20B | 0.96 |
C9—H9 | 0.93 | C20—H20C | 0.96 |
C10—C11 | 1.382 (4) | C21—F3 | 1.310 (4) |
C10—H10 | 0.93 | C21—F2 | 1.323 (5) |
C11—C12 | 1.387 (4) | C21—F1 | 1.327 (4) |
C11—H11 | 0.93 | C21—S1 | 1.805 (4) |
C13—C15 | 1.515 (4) | S1—O1 | 1.423 (3) |
C13—C14 | 1.531 (4) | S1—O2 | 1.430 (2) |
C13—C16 | 1.534 (4) | S1—O3 | 1.438 (2) |
C12—P1—C1 | 93.93 (13) | C13—C14—H14C | 109.5 |
C12—P1—C17 | 109.98 (13) | H14A—C14—H14C | 109.5 |
C1—P1—C17 | 111.29 (14) | H14B—C14—H14C | 109.5 |
C12—P1—C13 | 110.82 (14) | C13—C15—H15A | 109.5 |
C1—P1—C13 | 109.20 (12) | C13—C15—H15B | 109.5 |
C17—P1—C13 | 118.82 (14) | H15A—C15—H15B | 109.5 |
C2—C1—C6 | 120.9 (3) | C13—C15—H15C | 109.5 |
C2—C1—P1 | 130.3 (2) | H15A—C15—H15C | 109.5 |
C6—C1—P1 | 108.8 (2) | H15B—C15—H15C | 109.5 |
C3—C2—C1 | 118.8 (3) | C13—C16—H16A | 109.5 |
C3—C2—H2 | 120.6 | C13—C16—H16B | 109.5 |
C1—C2—H2 | 120.6 | H16A—C16—H16B | 109.5 |
C4—C3—C2 | 120.4 (3) | C13—C16—H16C | 109.5 |
C4—C3—H3 | 119.8 | H16A—C16—H16C | 109.5 |
C2—C3—H3 | 119.8 | H16B—C16—H16C | 109.5 |
C3—C4—C5 | 121.2 (3) | C19—C17—C20 | 109.4 (3) |
C3—C4—H4 | 119.4 | C19—C17—C18 | 110.7 (3) |
C5—C4—H4 | 119.4 | C20—C17—C18 | 109.2 (3) |
C4—C5—C6 | 119.6 (3) | C19—C17—P1 | 110.9 (2) |
C4—C5—H5 | 120.2 | C20—C17—P1 | 106.1 (2) |
C6—C5—H5 | 120.2 | C18—C17—P1 | 110.5 (2) |
C5—C6—C1 | 119.1 (3) | C17—C18—H18A | 109.5 |
C5—C6—C7 | 126.6 (3) | C17—C18—H18B | 109.5 |
C1—C6—C7 | 114.3 (3) | H18A—C18—H18B | 109.5 |
C8—C7—C12 | 119.1 (3) | C17—C18—H18C | 109.5 |
C8—C7—C6 | 127.0 (3) | H18A—C18—H18C | 109.5 |
C12—C7—C6 | 113.9 (3) | H18B—C18—H18C | 109.5 |
C9—C8—C7 | 119.6 (3) | C17—C19—H19A | 109.5 |
C9—C8—H8 | 120.2 | C17—C19—H19B | 109.5 |
C7—C8—H8 | 120.2 | H19A—C19—H19B | 109.5 |
C10—C9—C8 | 121.5 (3) | C17—C19—H19C | 109.5 |
C10—C9—H9 | 119.3 | H19A—C19—H19C | 109.5 |
C8—C9—H9 | 119.3 | H19B—C19—H19C | 109.5 |
C9—C10—C11 | 119.8 (3) | C17—C20—H20A | 109.5 |
C9—C10—H10 | 120.1 | C17—C20—H20B | 109.5 |
C11—C10—H10 | 120.1 | H20A—C20—H20B | 109.5 |
C10—C11—C12 | 119.4 (3) | C17—C20—H20C | 109.5 |
C10—C11—H11 | 120.3 | H20A—C20—H20C | 109.5 |
C12—C11—H11 | 120.3 | H20B—C20—H20C | 109.5 |
C11—C12—C7 | 120.6 (3) | F3—C21—F2 | 107.3 (4) |
C11—C12—P1 | 130.3 (2) | F3—C21—F1 | 107.1 (3) |
C7—C12—P1 | 109.1 (2) | F2—C21—F1 | 106.6 (3) |
C15—C13—C14 | 110.7 (3) | F3—C21—S1 | 112.9 (3) |
C15—C13—C16 | 109.9 (3) | F2—C21—S1 | 110.7 (3) |
C14—C13—C16 | 108.9 (3) | F1—C21—S1 | 111.9 (3) |
C15—C13—P1 | 111.3 (2) | O1—S1—O2 | 115.83 (15) |
C14—C13—P1 | 110.4 (2) | O1—S1—O3 | 114.24 (17) |
C16—C13—P1 | 105.4 (2) | O2—S1—O3 | 114.32 (15) |
C13—C14—H14A | 109.5 | O1—S1—C21 | 103.84 (18) |
C13—C14—H14B | 109.5 | O2—S1—C21 | 103.35 (17) |
H14A—C14—H14B | 109.5 | O3—S1—C21 | 103.01 (18) |
C12—P1—C1—C2 | −178.5 (3) | C17—P1—C12—C11 | 64.7 (3) |
C17—P1—C1—C2 | −65.2 (3) | C13—P1—C12—C11 | −68.7 (3) |
C13—P1—C1—C2 | 67.9 (3) | C1—P1—C12—C7 | −0.2 (2) |
C12—P1—C1—C6 | 1.2 (2) | C17—P1—C12—C7 | −114.5 (2) |
C17—P1—C1—C6 | 114.4 (2) | C13—P1—C12—C7 | 112.1 (2) |
C13—P1—C1—C6 | −112.5 (2) | C12—P1—C13—C15 | 74.3 (3) |
C6—C1—C2—C3 | 2.3 (4) | C1—P1—C13—C15 | 176.4 (2) |
P1—C1—C2—C3 | −178.1 (2) | C17—P1—C13—C15 | −54.5 (3) |
C1—C2—C3—C4 | −1.8 (5) | C12—P1—C13—C14 | −162.4 (2) |
C2—C3—C4—C5 | 0.4 (6) | C1—P1—C13—C14 | −60.2 (3) |
C3—C4—C5—C6 | 0.6 (6) | C17—P1—C13—C14 | 68.8 (3) |
C4—C5—C6—C1 | −0.1 (6) | C12—P1—C13—C16 | −44.9 (2) |
C4—C5—C6—C7 | −179.1 (4) | C1—P1—C13—C16 | 57.2 (2) |
C2—C1—C6—C5 | −1.3 (5) | C17—P1—C13—C16 | −173.7 (2) |
P1—C1—C6—C5 | 179.0 (3) | C12—P1—C17—C19 | 179.3 (2) |
C2—C1—C6—C7 | 177.8 (3) | C1—P1—C17—C19 | 76.6 (3) |
P1—C1—C6—C7 | −1.9 (3) | C13—P1—C17—C19 | −51.5 (3) |
C5—C6—C7—C8 | 1.2 (6) | C12—P1—C17—C20 | 60.7 (3) |
C1—C6—C7—C8 | −177.9 (3) | C1—P1—C17—C20 | −42.0 (3) |
C5—C6—C7—C12 | −179.1 (3) | C13—P1—C17—C20 | −170.1 (2) |
C1—C6—C7—C12 | 1.9 (4) | C12—P1—C17—C18 | −57.6 (3) |
C12—C7—C8—C9 | −1.1 (5) | C1—P1—C17—C18 | −160.3 (2) |
C6—C7—C8—C9 | 178.6 (3) | C13—P1—C17—C18 | 71.6 (3) |
C7—C8—C9—C10 | 1.3 (6) | F3—C21—S1—O1 | 178.2 (3) |
C8—C9—C10—C11 | 0.0 (5) | F2—C21—S1—O1 | −61.4 (3) |
C9—C10—C11—C12 | −1.5 (5) | F1—C21—S1—O1 | 57.3 (3) |
C10—C11—C12—C7 | 1.8 (4) | F3—C21—S1—O2 | −60.5 (3) |
C10—C11—C12—P1 | −177.4 (2) | F2—C21—S1—O2 | 59.9 (3) |
C8—C7—C12—C11 | −0.5 (5) | F1—C21—S1—O2 | 178.6 (3) |
C6—C7—C12—C11 | 179.8 (3) | F3—C21—S1—O3 | 58.8 (3) |
C8—C7—C12—P1 | 178.9 (3) | F2—C21—S1—O3 | 179.2 (3) |
C6—C7—C12—P1 | −0.9 (3) | F1—C21—S1—O3 | −62.1 (3) |
C1—P1—C12—C11 | 179.1 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O1i | 0.93 | 2.49 | 3.381 (4) | 161 |
C19—H19A···O2ii | 0.96 | 2.52 | 3.458 (4) | 165 |
C11—H11···O3iii | 0.93 | 2.7 | 3.601 (4) | 162 |
C15—H15B···O3iii | 0.96 | 2.69 | 3.470 (4) | 138 |
Symmetry codes: (i) x+1/2, −y+1/2, −z+7/4; (ii) y, x, −z+2; (iii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C20H26P+·CF3O3S− |
Mr | 446.45 |
Crystal system, space group | Tetragonal, P41212 |
Temperature (K) | 293 |
a, c (Å) | 12.1339 (10), 30.057 (2) |
V (Å3) | 4425.4 (6) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.26 |
Crystal size (mm) | 0.4 × 0.26 × 0.2 |
Data collection | |
Diffractometer | Bruker SMART 1K CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2008) |
Tmin, Tmax | 0.902, 0.949 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 25275, 5502, 3241 |
Rint | 0.101 |
(sin θ/λ)max (Å−1) | 0.669 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.054, 0.117, 0.99 |
No. of reflections | 5502 |
No. of parameters | 268 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.17, −0.25 |
Absolute structure | Flack (1983), 2283 Friedel pairs |
Absolute structure parameter | 0.05 (11) |
Computer programs: SMART-NT (Bruker, 1998), SAINT-Plus (Bruker, 2008), SAINT-Plus and XPREP (Bruker, 2008), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 2012).
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O1i | 0.93 | 2.49 | 3.381 (4) | 161.4 |
C19—H19A···O2ii | 0.96 | 2.52 | 3.458 (4) | 165 |
C11—H11···O3iii | 0.93 | 2.7 | 3.601 (4) | 162 |
C15—H15B···O3iii | 0.96 | 2.69 | 3.470 (4) | 138.2 |
Symmetry codes: (i) x+1/2, −y+1/2, −z+7/4; (ii) y, x, −z+2; (iii) x+1, y, z. |
Acknowledgements
The University of Witwatersrand is thanked for the use of their diffractometer. The research fund of the University of Johannesburg is gratefully acknowledged.
References
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The introduction of a cyclopalladated compound as a robust catalyst (Herrman et al., 2003) for Heck and cross-coupling reactions resulted in the design of structurally related palladacycles, phosphapalladacycles in particular (Beletskaya & Cheprakov, 2004). However, growing evidence suggests that palladacycles are disassembled during the pre-activation stage to yield low ligated Pd0 species as the actual catalyst (d'Orlye & Jutland, 2005). This is further exemplified by our finding that the use of palladacycle (II in Fig. 1), an effective amination catalyst (Beletskaya & Cheprakov, 2004), as a source of palladium together with triphenylphosphine and a strong acid provided an extremely active catalytic system for the hydromethoxylation of alkenes (Omondi et al., 2011 and Williams et al., 2008). In the reaction medium compound II (Fig. 1) was rapidly converted into tetrakistriphenylphosphinepalladium(0) which acted as the actual catalyst. The facile formation of Pd0 resulted from acid catalyzed elimination from the palladacycle. This treatment of II with ten equivalents of trifluoromethanesulfonic acid at room temperature resulted in the formation of colloidal palladium and the title compound (I in Fig. 1), the structure of which was confirmed by single-crystal X-ray crystallography.
The title compound I (Fig. 2 and Scheme 1) is a salt consisting of phospholium cations and trifluoromethanesulfonate anions. All ions lie on general positions in the unit cell with no discernible differences in the bond distances of the coordination polyhedron of the phosphorus environment. The bond angles at the phosphorus center shows significant deviations from the expected 109.5° for the tetrahedral shape with biphenyl—P—biphenyl = 93.93 (13)° and t-Bu—P—t-Bu = 118.82 (14)°. These deviations can be ascribed to the somewhat strained 5-membered cyclisation of the dibenzo fragment to form the phospholium ring. This pinching effect in turn allows for more space for the bulky tertiary butyl groups positioned above and below the plane formed by the tricyclic phospholium conjugate and hence the observed t-Bu—P—t-Bu angle. The tricyclic phospholium conjugate marginally deviates from planarity (C1—C6—C7—C12 = 1.9 (4)°), and would have been the primary route to alleviate stress from the pinching effect. Data extracted from the Cambridge Structural Database (Allen, 2002) for the torsion angle between the planes shows a mean value of 1.72° (126 observations). The general trend seems to be that substituents opposite the phospholium cycle forces it to be planar. The preferred orientation of the tertiary butyls are due to several weak C—H···O interactions observed between ions (see Table 1).