Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803006561/tk6098sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803006561/tk6098Isup2.hkl |
CCDC reference: 214592
Key indicators
- Single-crystal X-ray study
- T = 295 K
- Mean (C-C) = 0.004 Å
- R factor = 0.048
- wR factor = 0.154
- Data-to-parameter ratio = 19.0
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Alert Level C:
PLAT_320 Alert C Check Hybridisation of C(21) in Main Residue ?
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check
The title compound, (I), was synthesized according to the method of Grushin (2001). A mixture of palladium acetate (5 mg), 1,4-bis(diphenylphosphino)butane (2.00 g, 4.8 mmol), 1,2-dibromoethane (1.8 g, 9.6 mmol) and dichloromethane (5 ml) was stirred for 30 min. Aqueous sodium hydroxide (20% w/w, 5 ml) was added and the mixture stirred at room temperature for 3 d. Dichloromethane (15 ml) was then added and the organic phase filtered through a silica plug which was then washed with dichloromethane–ethyl acetate (5:3 v/v, 40 ml). The combined organic solutions were evaporated to dryness. The solid residue was dissolved in boiling dichloromethane (15 ml). Ether (50 ml) was added and the solution left to stand at room temperature for 2 h, yielding colourless crystals of (I). A crystal suitable for X-ray diffraction studies was grown by slow diffusion of methanol into a solution of (I) in dichloromethane. Analysis found: C 76.2, H 6.4%; calculated for C28H28OP2: C 76.0, H 6.4%. νmax (KBr) cm−1 1182 (P═O). δH (400 MHz, CDCl3, p.p.m.) 1.4 (2H, m, CH2), 1.7 (2H, m, CH2), 1.9 (2H, m, CH2), 2.15 (2H, m, CH2), 7.20–7.75 (20H, m, Ph). δP (161.9 MHz, CDCl3, p.p.m.) 15.82–15.69 (d, PPh2), 33.04–33.24 (d, OPPh2).
H atoms were included in the refinement at calculated positions in the riding-model approximation.
Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1999); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1999).; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON for Windows (Spek, 1999); software used to prepare material for publication: SHELXL97.
Fig. 1. The molecular configuration and atom-labelling scheme for (I). Ellipsoids are at the 30% probability level. |
C28H28OP2 | Z = 1 |
Mr = 442.44 | F(000) = 234 |
Triclinic, P1 | Dx = 1.228 Mg m−3 |
Hall symbol: -P 1 | Melting point = 463–464 K |
a = 8.927 (2) Å | Mo Kα radiation, λ = 0.71069 Å |
b = 12.514 (3) Å | Cell parameters from 25 reflections |
c = 5.802 (2) Å | θ = 12.6–17.2° |
α = 102.98 (2)° | µ = 0.20 mm−1 |
β = 102.23 (3)° | T = 295 K |
γ = 100.71 (2)° | Prismatic, colourless |
V = 598.5 (3) Å3 | 0.50 × 0.20 × 0.15 mm |
Rigaku AFC-7R diffractometer | Rint = 0.026 |
Radiation source: Rigaku rotating anode | θmax = 27.5°, θmin = 2.6° |
Graphite monochromator | h = −11→11 |
ω–2θ scans | k = −16→15 |
3238 measured reflections | l = −3→7 |
2752 independent reflections | 3 standard reflections every 150 reflections |
2133 reflections with I > 2σ(I) | intensity decay: 0.5% |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.048 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.154 | H-atom parameters constrained |
S = 0.86 | w = 1/[σ2(Fo2) + (0.1P)2 + 0.507P] where P = (Fo2 + 2Fc2)/3 |
2752 reflections | (Δ/σ)max < 0.001 |
145 parameters | Δρmax = 0.28 e Å−3 |
0 restraints | Δρmin = −0.28 e Å−3 |
C28H28OP2 | γ = 100.71 (2)° |
Mr = 442.44 | V = 598.5 (3) Å3 |
Triclinic, P1 | Z = 1 |
a = 8.927 (2) Å | Mo Kα radiation |
b = 12.514 (3) Å | µ = 0.20 mm−1 |
c = 5.802 (2) Å | T = 295 K |
α = 102.98 (2)° | 0.50 × 0.20 × 0.15 mm |
β = 102.23 (3)° |
Rigaku AFC-7R diffractometer | Rint = 0.026 |
3238 measured reflections | 3 standard reflections every 150 reflections |
2752 independent reflections | intensity decay: 0.5% |
2133 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.154 | H-atom parameters constrained |
S = 0.86 | Δρmax = 0.28 e Å−3 |
2752 reflections | Δρmin = −0.28 e Å−3 |
145 parameters |
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 | Occ. (<1) | |
P1 | 0.65422 (6) | 0.83393 (5) | 0.03061 (11) | 0.0430 (2) | |
O1 | 0.6811 (5) | 0.8512 (3) | 0.2806 (6) | 0.0645 (9) | 0.50 |
C1A | 0.6990 (2) | 0.70021 (18) | −0.1015 (4) | 0.0462 (5) | |
C1B | 0.4514 (2) | 0.81581 (17) | −0.1441 (4) | 0.0416 (5) | |
C2A | 0.6673 (4) | 0.6513 (2) | −0.3496 (6) | 0.0734 (8) | |
C2B | 0.3325 (3) | 0.7541 (2) | −0.0705 (5) | 0.0579 (6) | |
C3A | 0.7037 (5) | 0.5488 (3) | −0.4348 (7) | 0.0904 (11) | |
C3B | 0.1752 (3) | 0.7383 (2) | −0.1886 (7) | 0.0725 (9) | |
C4A | 0.7705 (5) | 0.4955 (3) | −0.2796 (9) | 0.0884 (11) | |
C4B | 0.1349 (3) | 0.7840 (3) | −0.3795 (6) | 0.0742 (9) | |
C5A | 0.8059 (5) | 0.5434 (3) | −0.0369 (9) | 0.0923 (12) | |
C5B | 0.2503 (3) | 0.8458 (3) | −0.4539 (5) | 0.0712 (8) | |
C6A | 0.7702 (4) | 0.6462 (3) | 0.0565 (6) | 0.0698 (8) | |
C6B | 0.4085 (3) | 0.8611 (2) | −0.3378 (5) | 0.0570 (6) | |
C11 | 0.7732 (2) | 0.93418 (16) | −0.0831 (4) | 0.0400 (4) | |
C21 | 0.9487 (2) | 0.95868 (17) | 0.0481 (4) | 0.0417 (5) | |
H2A | 0.6210 | 0.6881 | −0.4617 | 0.088* | |
H2B | 0.3597 | 0.7231 | 0.0631 | 0.068* | |
H3A | 0.6798 | 0.5155 | −0.6059 | 0.108* | |
H3B | 0.0951 | 0.6949 | −0.1406 | 0.087* | |
H4A | 0.7934 | 0.4253 | −0.3382 | 0.106* | |
H4B | 0.0266 | 0.7743 | −0.4597 | 0.087* | |
H5A | 0.8556 | 0.5077 | 0.0770 | 0.111* | |
H5B | 0.2216 | 0.8770 | −0.5865 | 0.084* | |
H6A | 0.7950 | 0.6790 | 0.2286 | 0.083* | |
H6B | 0.4874 | 0.9032 | −0.3912 | 0.067* | |
H11A | 0.7400 | 0.9921 | −0.0584 | 0.044* | |
H11B | 0.7570 | 0.8937 | −0.2792 | 0.044* | |
H21A | 0.9755 | 0.8818 | 0.0023 | 0.044* | |
H21B | 0.9634 | 1.0103 | 0.2240 | 0.044* |
U11 | U22 | U33 | U12 | U13 | U23 | |
P1 | 0.0383 (3) | 0.0411 (3) | 0.0502 (3) | 0.0063 (2) | 0.0115 (2) | 0.0167 (2) |
O1 | 0.077 (2) | 0.065 (2) | 0.0479 (19) | 0.0127 (18) | 0.0167 (17) | 0.0124 (17) |
C1A | 0.0387 (10) | 0.0375 (10) | 0.0627 (14) | 0.0059 (8) | 0.0129 (9) | 0.0178 (10) |
C1B | 0.0364 (10) | 0.0387 (10) | 0.0489 (11) | 0.0091 (8) | 0.0155 (8) | 0.0065 (9) |
C2A | 0.098 (2) | 0.0522 (15) | 0.0722 (18) | 0.0282 (15) | 0.0218 (16) | 0.0150 (13) |
C2B | 0.0476 (13) | 0.0491 (13) | 0.0816 (18) | 0.0100 (10) | 0.0287 (12) | 0.0177 (12) |
C3A | 0.125 (3) | 0.0554 (17) | 0.097 (3) | 0.0284 (18) | 0.049 (2) | 0.0091 (17) |
C3B | 0.0426 (13) | 0.0546 (15) | 0.114 (3) | 0.0030 (11) | 0.0322 (15) | 0.0065 (16) |
C4A | 0.102 (3) | 0.0486 (16) | 0.138 (3) | 0.0318 (16) | 0.064 (2) | 0.0294 (19) |
C4B | 0.0378 (12) | 0.0668 (17) | 0.093 (2) | 0.0117 (12) | 0.0041 (13) | −0.0143 (16) |
C5A | 0.097 (3) | 0.075 (2) | 0.137 (3) | 0.050 (2) | 0.042 (2) | 0.057 (2) |
C5B | 0.0582 (16) | 0.087 (2) | 0.0616 (16) | 0.0295 (15) | 0.0012 (13) | 0.0102 (15) |
C6A | 0.0722 (18) | 0.0657 (17) | 0.0789 (19) | 0.0264 (14) | 0.0154 (15) | 0.0313 (15) |
C6B | 0.0448 (12) | 0.0708 (16) | 0.0574 (14) | 0.0155 (11) | 0.0128 (10) | 0.0213 (12) |
C11 | 0.0353 (10) | 0.0344 (10) | 0.0513 (12) | 0.0081 (8) | 0.0125 (8) | 0.0132 (8) |
C21 | 0.0346 (10) | 0.0363 (10) | 0.0537 (12) | 0.0076 (8) | 0.0115 (9) | 0.0127 (9) |
P1—O1 | 1.379 (3) | C11—C21 | 1.529 (3) |
P1—C1A | 1.830 (2) | C21—C21i | 1.531 (3) |
P1—C1B | 1.823 (2) | C2A—H2A | 0.9473 |
P1—C11 | 1.820 (2) | C2B—H2B | 0.9490 |
C1A—C2A | 1.376 (4) | C3A—H3A | 0.9466 |
C1A—C6A | 1.376 (4) | C3B—H3B | 0.9444 |
C1B—C2B | 1.393 (3) | C4A—H4A | 0.9440 |
C1B—C6B | 1.384 (3) | C4B—H4B | 0.9520 |
C2A—C3A | 1.390 (5) | C5A—H5A | 0.9567 |
C2B—C3B | 1.382 (4) | C5B—H5B | 0.9479 |
C3A—C4A | 1.342 (6) | C6A—H6A | 0.9503 |
C3B—C4B | 1.369 (5) | C6B—H6B | 0.9474 |
C4A—C5A | 1.343 (7) | C11—H11A | 0.8276 |
C4B—C5B | 1.374 (5) | C11—H11B | 1.1028 |
C5A—C6A | 1.401 (6) | C21—H21A | 1.0252 |
C5B—C6B | 1.387 (4) | C21—H21B | 1.0448 |
O1—P1—C1A | 108.97 (19) | C3B—C2B—H2B | 119.58 |
O1—P1—C1B | 117.0 (2) | C2A—C3A—H3A | 119.29 |
O1—P1—C11 | 118.56 (19) | C4A—C3A—H3A | 119.30 |
C1A—P1—C1B | 102.84 (10) | C2B—C3B—H3B | 120.41 |
C1A—P1—C11 | 102.76 (10) | C4B—C3B—H3B | 119.64 |
C1B—P1—C11 | 104.76 (10) | C3A—C4A—H4A | 121.13 |
P1—C1A—C2A | 123.81 (19) | C5A—C4A—H4A | 119.61 |
P1—C1A—C6A | 118.1 (2) | C3B—C4B—H4B | 120.19 |
C2A—C1A—C6A | 118.1 (2) | C5B—C4B—H4B | 119.52 |
P1—C1B—C2B | 116.70 (18) | C4A—C5A—H5A | 120.68 |
P1—C1B—C6B | 124.72 (18) | C6A—C5A—H5A | 118.20 |
C2B—C1B—C6B | 118.6 (2) | C4B—C5B—H5B | 119.84 |
C1A—C2A—C3A | 120.1 (3) | C6B—C5B—H5B | 120.03 |
C1B—C2B—C3B | 120.7 (2) | C1A—C6A—H6A | 119.70 |
C2A—C3A—C4A | 121.4 (4) | C5A—C6A—H6A | 120.39 |
C2B—C3B—C4B | 119.9 (3) | C1B—C6B—H6B | 119.99 |
C3A—C4A—C5A | 119.3 (4) | C5B—C6B—H6B | 119.62 |
C3B—C4B—C5B | 120.3 (3) | P1—C11—H11A | 106.17 |
C4A—C5A—C6A | 121.1 (4) | P1—C11—H11B | 106.70 |
C4B—C5B—C6B | 120.1 (3) | C21—C11—H11A | 111.35 |
C1A—C6A—C5A | 119.9 (3) | C21—C11—H11B | 108.18 |
C1B—C6B—C5B | 120.4 (3) | H11A—C11—H11B | 113.32 |
P1—C11—C21 | 111.04 (15) | C11—C21—H21A | 103.89 |
C11—C21—C21i | 111.89 (18) | C11—C21—H21B | 106.15 |
C1A—C2A—H2A | 119.55 | H21A—C21—H21B | 127.48 |
C3A—C2A—H2A | 120.30 | C21i—C21—H21A | 108.14 |
C1B—C2B—H2B | 119.71 | C21i—C21—H21B | 99.18 |
O1—P1—C1A—C2A | 172.1 (3) | C6A—C1A—C2A—C3A | 1.5 (5) |
O1—P1—C1A—C6A | −8.7 (3) | C2A—C1A—C6A—C5A | −1.0 (5) |
C1B—P1—C1A—C2A | 47.3 (2) | P1—C1B—C2B—C3B | 178.5 (2) |
C1B—P1—C1A—C6A | −133.5 (2) | C6B—C1B—C2B—C3B | 0.1 (4) |
C11—P1—C1A—C2A | −61.3 (2) | C2B—C1B—C6B—C5B | 0.5 (4) |
C11—P1—C1A—C6A | 117.9 (2) | P1—C1B—C6B—C5B | −177.7 (2) |
O1—P1—C1B—C2B | −38.2 (3) | C1A—C2A—C3A—C4A | −0.3 (6) |
O1—P1—C1B—C6B | 140.1 (3) | C1B—C2B—C3B—C4B | −0.3 (5) |
C1A—P1—C1B—C2B | 81.2 (2) | C2A—C3A—C4A—C5A | −1.4 (7) |
C1A—P1—C1B—C6B | −100.6 (2) | C2B—C3B—C4B—C5B | −0.2 (5) |
C11—P1—C1B—C2B | −171.73 (18) | C3A—C4A—C5A—C6A | 1.8 (7) |
C11—P1—C1B—C6B | 6.5 (2) | C3B—C4B—C5B—C6B | 0.8 (5) |
O1—P1—C11—C21 | 47.2 (3) | C4A—C5A—C6A—C1A | −0.6 (6) |
C1A—P1—C11—C21 | −73.00 (16) | C4B—C5B—C6B—C1B | −1.0 (5) |
C1B—P1—C11—C21 | 179.82 (17) | P1—C11—C21—C21i | 178.99 (15) |
P1—C1A—C6A—C5A | 179.7 (3) | C11—C21—C21i—C11i | 180.0 (4) |
P1—C1A—C2A—C3A | −179.3 (3) |
Symmetry code: (i) −x+2, −y+2, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C6A—H6A···O1 | 0.95 | 2.53 | 2.933 (6) | 105 |
C11—H11B···O1ii | 1.10 | 2.41 | 3.473 (4) | 163 |
Symmetry code: (ii) x, y, z−1. |
Experimental details
Crystal data | |
Chemical formula | C28H28OP2 |
Mr | 442.44 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 295 |
a, b, c (Å) | 8.927 (2), 12.514 (3), 5.802 (2) |
α, β, γ (°) | 102.98 (2), 102.23 (3), 100.71 (2) |
V (Å3) | 598.5 (3) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 0.20 |
Crystal size (mm) | 0.50 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Rigaku AFC-7R diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3238, 2752, 2133 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.048, 0.154, 0.86 |
No. of reflections | 2752 |
No. of parameters | 145 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.28, −0.28 |
Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1999), MSC/AFC Diffractometer Control Software, TEXSAN for Windows (Molecular Structure Corporation, 1999)., SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON for Windows (Spek, 1999), SHELXL97.
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Tertiary phosphine oxides have proven utility as coordinating ligands in complex chemistry as well as being useful as aids for crystallization (Etter & Baures, 1988) through simple linear hydrogen-bonding associations between the oxide group and a proton-donating group, such as a carboxylic acid (Lynch et al., 1992, 1997; Smith et al., 1997, 1998). The parent tertiary phosphines, e.g. triphenylphosphine, are likewise useful as bulky ligands for stabilization of metal ions such as copper(I), silver(I) and gold(I), and extension of the ligand capacity via multiple pendant phosphinoyl groups has potential for formation of useful polymeric structures. It has been observed (Heinze et al., 1997) that partial oxidation of the phosphorus group in uncoordinated `dangling arms' of such multidentate ligands occurs quite easily. The first reported example of this was in the ReIII–carbonyl complex with bis(diphenylphosphino)methane (Carriedo et al., 1990), where the occupancy factor for O was 0.30. For the PdII–chloride complex with a similar diphosphine (Sevillano et al., 2000), the pendant arm was 50% oxidized. The phenomenon has also been observed in structures of uncoordinated phosphines, such as 1,1,1-tris(diphenylphosphinomethyl)propane (Chekhlov, 2000), where the three O atoms had occupancies of 11.3, 13.5 and 39.0%. In another example, the triphenylphosphine oxide–triphenylmethanol dimer (Steiner, 2000), the two molecules are related by pseudosymmetry across a crystallographic inversion centre (50% occupancy). We have also found that an isomorphous crystal series exists for the three isolated phosphine oxides (25.0, 50.0, 100.0%) of [4-(N,N-dimethylamino)phenyl]diphenylphosphine oxide (Lynch et al., 2003).
The cell dimensions of the title compound, (I), are similar to those previously reported for the dioxide (Fontes et al., 1991) [comparative (room temperature) permuted unit cell (Fontes et al., 1991): a = 8.862 (1), b = 12.517 (2), c = 5.862 (1) Å, α = 102.67 (1), β = 104.22 (1), γ = 100.29 (1)°, V = 592.4 (2) Å3]. Our determination in (I) has confirmed the presence of 50% occupancy (see below) for the oxygen sites which are statistically distributed across an inversion centre in the cell (Fig. 1). This result is consistent with the analytical and spectroscopic data that one P atom is oxidized while the other is unoxidized.
Another interesting and previously unreported phenomenon is the presence of significant P—O bond shortening for (I) [1.379 (3) Å] and for all other known `partial oxides', compared to 1.481 (2) Å in the `full oxide' (Fontes et al., 1991) and in both triphenylphosphine oxide [1.483 (2) and 1.484 (1) Å for the two monoclinic modifications (Ruban & Zabel, 1976; Spek, 1987)] and in triphenylphosphine oxide–carboxylic acid adducts [1.49 Å (mean); Smith et al., 1998]. The value in (I) is similar to distances for other `50% oxides' [1.378 (3) (Steiner, 2000), 1.39 (2) (Sevillano, 2000) and 1.357 (4) Å (Lynch et al. 2002)], and compares with 1.399 (4) (11.3%), 1.295 (14) (13.5%) and 1.368 (5) Å (39.0%) (Chekhlov, 2000), and 1.280 (4) Å (25.0%) (Lynch et al., 2003). The 31P NMR chemical shift data and P═O IR vibrational frequency data for (I) are typical for `normal' arylphosphine oxide P═O bonds, e.g. ν (P═O) for (I) (1182 cm−1) cf. 1185 cm−1 for 1,4-bis(diphenylphosphinoyl)butane (Higgins et al., 1987). This indicates that the apparent shortening of the P—O bond in structures with partial occupancy of the O atoms is an probably an artefact of the structure refinement process. In this context, it is interesting to note that the C—P—O and C—P—C bond angles around the P atom in (I) are consistently larger (115° mean) and smaller (104° mean), respectively, than the corresponding angles in the full oxide (112.7° and mean 105.9°). This is consistent with the decrease in the P—O bond length arising from movement of the P atom site towards the O atom.
Stabilizing the conformation of the ring system is a short intramolecular contact between a ring H and the oxide O atom [C6A—H6A···O1 = 2.933 (6) Å]. As expected little intermolecular association is found in the unit cell of (I), with only one C—-H···O contact [C11–H11B···O1i = 3.473 (4) Å: symmetry code: (i) x, y, 1 + z].