Halogen addition to a frustrated Lewis pair

Article abstract of DOI:10.1002/ejic.201200288

The reactive intramolecular frustrated Lewis pair (FLP) Mes ₂PCH₂CH₂B(C₆F₅) ₂ reacts rapidly with thionyl chloride to yield the zwitterionic chlorination product [Mes₂PCl⁺]CH₂-CH ₂[BCl(C₆F₅)₂^-]. Analogous zwitterionic products were obtained by the reaction of the FLP with chlorine or bromine. Compounds [Mes₂PX⁺]CH₂CH ₂[BX(C₆F₅)₂^-] (X = Cl, Br) were characterized by X-ray crystal structure analyses. The reactive frustrated Lewis pair A reacts with thionyl chloride and halogens to yield the zwitterionic X⁺/X^- addition products B and C, respectively. Copyright

Full text of DOI:10.1002/ejic.201200288

Job/Unit: I20288
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Date: 27-06-12 09:44:38
Pages: 7
FULL PAPER
DOI: 10.1002/ejic.201200288
Halogen Addition to a Frustrated Lewis Pair
Silke Frömel,[a] Roland Fröhlich,[a][‡] Constantin G. Daniliuc,[a][‡] Gerald Kehr,[a] and
Gerhard Erker*[a]
Keywords: Frustrated Lewis pairs / Phosphorus / Boron / Halogens / Zwitterions
The reactive intramolecular frustrated Lewis pair (FLP)
Mes2PCH2CH2B(C6F5)2 reacts rapidly with thionyl chloride
products were obtained by the reaction of the FLP with
chlorine or bromine. Compounds [Mes2PX+]CH2CH2[BX-
(C6F5)2–] (X = Cl, Br) were characterized by X-ray crystal
structure analyses.
to
yield
the
zwitterionic
chlorination
product
[Mes2PCl+]CH2–CH2[BCl(C6F5)2–]. Analogous zwitterionic
acid might show a substantial influence. This was eventu-
ally the case, as we were able to show by treating the very
reactive intramolecular frustrated Lewis pair 4 (see below)
with thionyl chloride.
Introduction
Phosphorus halides of the general stoichiometry R3PX2
can feature any of three different structural types depending
on the nature of substituents R and the halide and the con-
ditions of their preparation. This structural trio contains
one pentacoordinate phosphorus compound, namely, the
trigonal-bipyramidal system 1, and two pseudotetrahedrally
coordinated phosphorus compounds. These are the phos-
phonium salt 2 and the unusually structured “spoke” ad-
duct 3, which may be regarded as a charge-transfer complex
(see Scheme 1).[1–3]
Results and Discussion
For this study, we generated the reactive FLP 4[13] in situ
by hydroboration of dimesityl(vinyl)phosphane with
HB(C6F5)2 (Piers’ borane). The yellow solution of 4 in
benzene was then treated on a preparative scale with a ten-
fold excess amount of thionyl chloride at room temperature.
After stirring overnight and workup with pentane, we iso-
lated the chlorinated product 5 as a white solid in 54%
yield. NMR spectroscopy showed that the product con-
tained small amounts (5–10%) of the side products 6 and 7
(for details, see below). Compound 5 was characterized by
X-ray diffraction. Suitable single crystals were obtained by
slow evaporation of solvent from a solution of 5 in dichlo-
romethane at low temperature.
The X-ray crystal-structure analysis of product 5 shows
that formally a Cl+/Cl– pair has been added to FLP 4. We
find a phosphorus center in a pseudotetrahedral ligand en-
vironment that features the P1–Cl1 unit [2.002(1) Å] and a
pseudotetrahedral borate unit with the B1–Cl2 bond
[1.925(5) Å]. The phosphonium and borate subunits are
connected by a –CH2–CH2– linker. In compound 5, this
attains a staggered conformation with the bulky Mes2PCl
and (C6F5)2BCl units oriented in an antiperiplanar manner
[P1–C1 1.795(4), C1–C2 1.527(5), C2–B1 1.627(6) Å; dihe-
dral angle P1–C1–C2–B1 –169.6(3)°]. A bulky mesityl sub-
stituent at the phosphorus atom is arranged in an antiperi-
planar fashion to the C1–C2 vector; a similar arrangement
is found for a C6F5 substituent at the boron atom [θ: C2–
C1–P1–C11 179.8(3), C1–C2–B1–C31 –177.7(3)°]. This
brings both the P1–Cl1 and B1–Cl2 vectors in gauche posi-
tions to the different faces of the central framework of 5
Scheme 1.
Frustrated Lewis pairs (FLPs) were shown to have ex-
traordinary abilities to bind and/or activate a great variety
of small molecules.[4] Most noteworthy is their often ob-
served heterolytic cleavage of dihydrogen[5] and its acti-
vation for metal-free catalytic hydrogenation processes.[6,7]
But FLPs might also add to a variety of alkenes, alkynes,
conjugated π-systems, to organic carbonyl compounds, to
CO2, to N2O, and even to NO.[8–11] Therefore, it was tempt-
ing to probe their reactivity towards halogens and haloge-
nating reagents.[12] Since some FLPs contain a reactive
tricoordinate phosphorus center, formation of any of the
three structural types (1–3) mentioned above might in prin-
ciple be feasible, but the presence of a strong boron Lewis
[a] Organisch-Chemisches Institut, Universität Münster,
Corrensstrasse 40, 48149 Münster, Germany
Fax: +49-251-83-36503
E-mail: erker@uni-muenster.de
[‡] X-ray crystal structure analyses
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201200288.
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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S. Frömel, R. Fröhlich, C. G. Daniliuc, G. Kehr, G. Erker
FULL PAPER
[trans-gauche arrangement; see Figure 1; θ: Cl1–P1–C1–C2
–65.1(3), C1–C2–B1–Cl2 66.5(4)°] (all values were taken
from molecule A).
Scheme 2.
Figure 1. View of the molecular structure of compound 5.
In solution, compound 5 shows typical phosphonium
and borate NMR spectroscopic resonances [δ = –2.5 ppm
Figure 2. Molecular structure of compound 7.
(11B); δ = –132.4, –160.9, –165.2 ppm (19F; Δδ19Fm,p
=
4.3 ppm); δ = +82.9 ppm (31P)]. It features the NMR spec-
troscopic signals of the bridging –PCH2–BCH2– unit at δ =
3.44/1.79 (1H) and 37.3/20.2 (13C) ppm, respectively.
HCl addition product 8 (see Scheme 3). The latter was char-
acterized by X-ray diffraction (for details, see the Support-
ing Information).
In this experiment, the pair of chlorine atoms from the
SOCl2 reagent was added to the P/B Lewis base/Lewis acid
pair of the reactive FLP 4, but the fate of the major fraction
of the remaining SO unit remained unclear. This was dif-
ferent when we treated the FLP 4 with only 0.33 equiv. of
thionyl chloride. In this case, we observed the formation of
three products (see Scheme 2) in a close to equimolar ratio
(5/6/7 = 10:12:9). We had previously described the phos-
phorus oxide product 6 and confirmed its heterocyclic
structure by X-ray diffraction.[14] The formation of the
phosphorus sulfide product 7 was confirmed by indepen-
dent synthesis within the scope of this study. Treatment of
the frustrated Lewis pair 4 with elemental sulfur in benzene
(room temp., 3 d) eventually gave 7, which was isolated in
61% as a colorless solid [δ = 59.9 ppm (31P); 0.0 ppm (11B);
–131.9, –158.8, –164.0 ppm (19F; Δδ19Fm,p = 5.2 ppm); 2.91,
Scheme 3.
We also treated FLP 4 with bromine and isolated the Br2
2.03 ppm (1H; –PCH2–BCH2–)]. Compound 7 was charac- addition product 9 as a pale yellow solid in 84% yield. The
terized by X-ray diffraction (single crystals from [D6]benz- compound features a 31P NMR spectroscopic signal at δ =
ene). In the crystal, compound 7 features the newly formed 62.4 ppm and an 11B NMR spectroscopic resonance at δ =
P–S bond [P1–S1 2.034(1) Å]. The sulfur atom is internally –3.7 ppm. The [B](C6F5)2 unit shows 19F NMR spectro-
coordinated to the boron atom [B1–S1 2.019(4) Å; P1–S1– scopic signals at δ = –131.4 (o), –160.6 (p), and –165.2 ppm
B1 96.7(1)°] and the resulting five-membered ring attains a (m). The small Δδ19Fm,p difference of only 4.6 ppm is typical
distorted twistlike conformation to minimize eclipsed inter- for a tetracoordinate boron atom in this ligand environ-
actions at the backbone (see Figure 2).
ment.
Compound 9 was characterized by an X-ray crystal
Compound 5 was also prepared by treatment of the in-
tramolecular FLP 4 with chlorine gas. In our experiment, structure analysis (see Figure 3). It shows the bulky
the Cl2 gas used was not dried; therefore, we obtained a Mes2PBr and (C6F5)2BBr units oriented in an antiperi-
mixture of the Cl2 addition product 5 and the respective planar fashion at the bridging –CH2–CH2– unit (θ: P1–
2
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Halogen Addition to a Frustrated Lewis Pair
KappaCCD diffractometer. Programs used: COLLECT (Nonius
B.V., 1998) for data collection, Denzo-SMN for data reduction,[18]
Denzo for absorption correction,[19] SHELXS-97 for structure
solution,[20] SHELXL-97 for structure refinement,[21] XP for graph-
ics (Bruker AXS, 2000). Graphics show the thermal ellipsoids with
50% probability, R values are given for the observed reflections,
wR2 values for all reflections. CCDC-858574 (for 5), -858575 (for
6), -858576 (for 7), 858577 (for 8), and 873310 (for 9) contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
C1–C2–B1 179.5°). The P–Br and B–Br vectors are also
found in a pseudo-antiperiplanar arrangement (θ: Br1–
P1····B1–Br2 167.6°).
Materials: Dimesityl(vinyl)phosphane,[13] bis(pentafluorophenyl)-
borane,[22] and {2-[bis(pentafluorophenyl)boryl]ethyl}dimesityl-
phosphane (4)[13] were prepared according to modified literature
procedures.
Treatment of 4 with Thionyl Chloride To Yield 5, 6, and 7: A mixture
of dimesityl(vinyl)phosphane (10.0 mg, 0.034 mmol) and bis(pen-
tafluorophenyl)borane (11.7 mg, 0.034 mmol, 1.0 equiv.) was dis-
solved in [D6]benzene (1 mL) and stirred until a yellow solution of
4
was formed. After addition of thionyl chloride (25 μL,
0.34 mmol, 10.0 equiv.), the solution immediately became colorless.
The reaction mixture was stirred for 90 min to yield a mixture of
compounds 5 (74%), 6 (6%), and 7 (20%) (from 19F NMR spec-
trum).
Figure 3. Molecular structure of compound 9.
1
NMR Spectroscopic Data of 5: H NMR (500 MHz, C6D6, 25 °C):
δ = 6.32 (d, 4JP,H = 5.5 Hz, 2 H, m-Mes), 3.44 (m, 1 H, PCH2), 1.90
(s, 6 H, o-CH3Mes), 1.792 (s, 3 H, p-CH3Mes), 1.790 (m, 1 H, BCH2)
ppm. 13C{1H} NMR (126 MHz, C6D6, 25 °C): δ = 148.5 (dm, 1JF,C
Conclusion
Our study shows that binding of the halide anion by
halogenoborate formation stabilizes the halogenophos-
phonium structure of the R3PX2 manifold. The straightfor-
4
2
≈ 241 Hz, o-C6F5), 145.9 (d, JP,C = 3.0 Hz, p-Mes), 141.9 (d, JP,C
1
= 12.3 Hz, o-Mes), 139.3 (dm, JF,C ≈ 241 Hz, p-C6F5), 137.5 (dm,
3
1JF,C ≈ 247 Hz, m-C6F5), 132.8 (d, JP,C = 13.0 Hz, m-Mes), 124.5
–
ward formation of the [Mes2PX+]CH2CH2[BX(C6F5)2 ]
1
1
(br., i-C6F5), 119.3 (d, JP,C = 76.3 Hz, i-Mes), 37.3 (d, JP,C
=
zwitterion (5, X = Cl; 9, X = Br) by treating the FLP 4
with either thionyl chloride or the elemental halogens
may potentially make the development of FLP-derived
[P](Hal)+ reagents and their chemistry an interesting alter-
native to the conventional methods.[15,16]
33.8 Hz, PCH2), 23.0 (d, JP,C = 4.7 Hz, o-CH3Mes), 20.7 (d, JP,C
= 1.6 Hz, p-CH3Mes), 20.2 (br., BCH2) ppm. 19F NMR (470 MHz,
C6D6, 25 °C): δ = –132.4 (m, 2 F, o-C6F5), –160.9 (t, JF,F = 20.8 Hz,
1 F, p-C6F5), –165.2 (m, 2 F, m-C6F5) [Δδ19Fm,p = 4.3] ppm.
11B{1H} NMR (160 MHz, C6D6, 25 °C): δ = –2.5 ppm. 31P{1H}
NMR (202 MHz, C6D6, 25 °C): δ = 82.9 (ν1/2 ≈ 15 Hz) ppm.
3
5
NMR Spectroscopic Data of 6:[14] 1H NMR (500 MHz, C6D6,
4
Experimental Section
25 °C): δ = 6.40 (d, JP,H = 4.5 Hz, 2 H, m-Mes), 2.44 (m, 2 H,
PCH2), 2.10 (s, 6 H, o-CH3Mes), 1.86 (s, 3 H, p-CH3Mes), 1.85
General Procedures: All syntheses that involve air- and moisture-
sensitive compounds were carried out by using standard Schlenk-
type glassware (or in a glovebox) under argon. Solvents were dried
with the procedure according to Grubbs[17] or were distilled from
appropriate drying agents and stored under argon. The following
instruments were used for physical characterization of the com-
pounds. NMR spectra: Bruker AV 300 spectrometer (1H: 300 MHz;
19F: 282 MHz; 11B: 96 MHz; 31P: 122 MHz), Varian Inova 500 (1H:
500 MHz; 13C: 126 MHz; 19F: 470 MHz; 11B: 160 MHz; 31P:
202 MHz), Varian Unity Plus 600 (1H: 600 MHz; 13C: 151 MHz;
19F: 564 MHz; 11B: 192 MHz; 31P: 243 MHz). 1H and 13C NMR
spectroscopy: chemical shifts (δ) are given relative to TMS and ref-
erenced to the solvent signal. 19F NMR spectroscopy: chemical
shifts (δ) are given relative to CFCl3 (external reference). 11B NMR
spectroscopy: chemical shifts (δ) are given relative to BF3·Et2O (ex-
ternal reference). NMR spectroscopic assignments are supported
by additional 2D NMR experiments. Elemental analyses were per-
formed with an Elementar Vario El III. IR spectra were recorded
with a Varian 3100 FTIR (Excalibur Series). Melting points were
obtained with a DSC Q20 (TA Instruments). Mass spectra were
recorded with an Orbitrap LTQ XL (Thermo Scientific). X-ray
crystal structure analyses: Data sets were collected with a Nonius
(BCH2; from gCOSY experiment) ppm. 13C{1H} NMR (126 MHz,
4
2
C6D6, 25 °C): δ = 143.4 (d, JP,C = 2.9 Hz, p-Mes), 142.0 (d, JP,C
3
= 11.3 Hz, o-Mes), 131.6 (d, JP,C = 11.7 Hz, m-Mes), 123.5 (d,
1JP,C = 96.2 Hz, i-Mes), 32.7 (d, JP,C = 53.6 Hz, PCH2), 22.2 (d,
1
3JP,C = 4.8 Hz, o-CH3Mes), 20.7 (p-CH3Mes; from gHSQC experi-
ment), not observed (BCH2), not listed (C6F5) ppm. 19F NMR
(470 MHz, C6D6, 25 °C): δ = –133.8 (m, 2 F, o-C6F5), –159.5 (t,
JF,F = 20.7 Hz, 1 F, p-C6F5), –164.5 (m, 2 F, m-C6F5) [Δδ19Fm,p
=
≈
5.0] ppm. 31P{1H} NMR (202 MHz, C6D6, 25 °C): δ = 80.0 (ν1/2
5 Hz) ppm.
1
NMR Spectroscopic Data of 7: H NMR (500 MHz, C6D6, 25 °C):
δ = 6.35 (d, 4JP,H = 4.4 Hz, 2 H, m-Mes), 2.93 (m, 1 H, PCH2), 2.07
(s, 6 H, o-CH3Mes), 2.03 (dm, JP,H = 31.9 Hz, 1 H, BCH2), 1.85 (s,
3
3 H, p-CH3Mes) ppm. 13C{1H} NMR (126 MHz, C6D6, 25 °C): δ =
4
142.4 (d, JP,C = 2.9 Hz, p-Mes), 141.1 (d, 2JP,C = 10.2 Hz, o-Mes),
132.1 (d, 3JPC = 11.5 Hz, m-Mes), 125.2 (d, 1JP,C = 73.5 Hz, i-Mes),
38.9 (d, 1JP,C = 43.6 Hz, PCH2), 22.8 (d, 3JP,C = 5.2 Hz, o-CH3Mes),
22.4 (br., BCH2; from gHSQC experiment), 20.6 (d, 5JP,C = 1.5 Hz,
p-CH3Mes), not listed (C6F5) ppm. 19F NMR (470 MHz, C6D6,
25 °C): δ = –131.8 (m, 2 F, o-C6F5), –158.9 (t, JF,F = 20.3 Hz, 1 F,
p-C6F5), –164.0 (m, 2 F, m-C6F5) [Δδ19Fm,p = 5.1] ppm. 31P{1H}
Eur. J. Inorg. Chem. 0000, 0–0
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S. Frömel, R. Fröhlich, C. G. Daniliuc, G. Kehr, G. Erker
FULL PAPER
NMR (202 MHz, C6D6, 25 °C): δ = 59.9 (m) ppm. 31P NMR
(202 MHz, C6D6, 25 °C): δ = 59.9 (tm, JP,H ≈ 31.2 Hz) ppm.
γ = 113.153(1)°, V = 1797.59(6) Å3, ρcalcd. = 1.411 gcm–3, μ =
3.405 mm–1, empirical absorption correction (0.460ՅTՅ0.848), Z
= 2, triclinic, space group P1 (no. 2), λ = 1.54178 Å, T = 223(2) K,
3
¯
Preparative Scale:
A
mixture of dimesityl(vinyl)phosphane
ω and φ scans, 23757 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ]
(50.0 mg, 0.17 mmol) and bis(pentafluorophenyl)borane (58.6 mg,
0.17 mmol, 1.0 equiv.) was dissolved in benzene (5 mL) and stirred
for 10 min. The yellow solution was added to a solution of thionyl
chloride (124 μL, 1.70 mmol, 10.0 equiv.) in benzene (1 mL). The
solution immediately became colorless. After stirring overnight, the
solvent was removed in vacuo. The residual white solid was washed
with n-pentane (3ϫ4 mL) and dried in vacuo to afford 5 (85%) as
a white powder and compounds 6 (5%) and 7 (10%) as side prod-
ucts (overall yield: 64%, 0.108 mmol, 76.0 mg). Crystals of 5 suit-
able for an X-ray crystal structure analysis were grown by slow
concentration of a solution of the product mixture in dichloro-
methane at –40 °C. C32H26BCl2F10P (5) (713.2): calcd. C 53.89, H
3.67; found C 54.30, H 3.75. The NMR spectroscopic data of the
compounds obtained in the preparative-scale reaction are consis-
tent with the NMR spectroscopic data of the “NMR-scale” reac-
tion.
= 0.60 Å–1, 6203 independent (Rint = 0.051) and 5124 observed
reflections [IՆ2σ(I)], 443 refined parameters, R = 0.061, wR2
=
0.169, max./min. residual electron density 0.69/–0.63 eÅ–3, the hy-
drogen atom at P was calculated from difference Fourier calcula-
tions, others calculated and refined as riding atoms; the second
disordered solvent molecule could not be identified, therefore
SQUEEZE was used.
Reaction of 4 with Sulfur To Yield 7: A mixture of dimesityl(vinyl)-
phosphane (30.0 mg, 0.101 mmol) and bis(pentafluorophenyl)bor-
ane (35.0 mg, 0.101 mmol, 1.0 equiv.) was dissolved in benzene
(3 mL) and stirred for 10 min. After addition of sulfur (4.0 mg,
0.12 mmol, 1.2 equiv.) to the yellow solution, the solution immedi-
ately became colorless, and the reaction mixture was stirred for 3 d.
Thereafter all volatiles were removed in vacuo, and the residue was
dried in vacuo to yield 7 as a white solid (61%, 0.06 mmol,
41.0 mg). Crystals of 7 suitable for an X-ray crystal structure analy-
sis were obtained from a solution of 7 in deuterated benzene in an
NMR spectroscopy tube at room temperature. M.p. 176 °C. ESI-
HRMS: calcd. for C32H27BF10PS 675.1504; found 675.1505. 1H
X-ray Crystal Structure Analysis of 5: C32H26BCl2F10P, Mr
=
713.21, colorless crystal 0.28ϫ0.10ϫ0.08 mm, a = 12.5699(6) Å,
b = 22.0482(14) Å, c = 25.4508(13) Å, β = 91.242(5)°, V =
7051.9(7) Å3, ρcalcd. = 1.344 gcm–3, μ = 2.754 mm–1, empirical ab-
sorption correction (0.513ՅTՅ0.810), Z = 8, monoclinic, space
group P21/c (no. 14), λ = 1.54178 Å, T = 223(2) K, ω and φ scans,
60860 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1,
12130 independent (Rint = 0.091) and 7405 observed reflections
[IՆ2σ(I)], 841 refined parameters, R = 0.060, wR2 = 0.168, max./
min. residual electron density 0.23/–0.30 eÅ–3, hydrogen atoms cal-
culated and refined as riding atoms, solvent molecule (probably
CH2Cl2) totally disordered, therefore SQUEEZE was used.
4
NMR (600 MHz, C6D6, 25 °C): δ = 6.33 (d, JP,H = 4.6 Hz, 2 H,
m-Mes), 2.91 (m, 1 H, PCH2), 2.06 (s, 6 H, o-CH3Mes), 2.03 (dm,
3JP,H = 31.9 Hz, 1 H, BCH2), 1.83 (s, 3 H, p-CH3Mes) ppm. 13C{1H}
1
NMR (151 MHz, C6D6, 25 °C): δ = 148.0 (dm, JF,C ≈ 240 Hz, o-
4
2
C6F5), 142.4 (d, JP,C = 2.9 Hz, p-Mes), 141.2 (d, JP,C = 10.4 Hz,
1
1
o-Mes), 139.7 (dm, JF,C ≈ 244 Hz, p-C6F5), 137.6 (dm, JF,C
≈
253 Hz, m-C6F5), 132.0 (d, 3JP,C = 11.2 Hz, m-Mes), 125.2 (d, 1JP,C
1
= 74.5 Hz, i-Mes), 122.0 (br., i-C6F5), 38.9 (d, JP,C = 43.2 Hz,
3
PCH2), 22.8 (d, JP,C = 5.0 Hz, o-CH3Mes), 22.4 (br., BCH2), 20.6
Reaction of 4 with Chlorine To Yield 5 and 8: A mixture of dimes-
ityl(vinyl)phosphane (100.0 mg, 0.34 mmol) and bis(pentafluoro-
phenyl)borane (117.0 mg, 0.34 mmol, 1.0 equiv.) was dissolved in
n-pentane (8 mL) and stirred for 30 min. Then chlorine gas was
introduced for 10 min. Immediately a white powder began to pre-
cipitate. The reaction mixture was stirred at room temperature for
5 h. Afterwards all volatiles were removed in vacuo to yield com-
pounds 5 and 8 (ratio 1:3; from 19F NMR spectrum) as a white
powder (overall yield: 88%, 0.30 mmol, 207.0 mg). Crystals of 8
suitable for an X-ray crystal structure analysis were grown by slow
concentration of a solution of the product mixture in dichloro-
methane at –40 °C.
(d, JP,C = 1.5 Hz, p-CH3Mes) ppm. 19F NMR (564 MHz, C6D6,
5
25 °C): δ = –131.9 (m, 2 F, o-C6F5), –158.8 (t, JF,F = 21.0 Hz, 1 F,
p-C6F5), –164.0 (m, 2 F, m-C6F5) [Δδ19Fm,p = 5.2] ppm. 11B{1H}
NMR (192 MHz, C6D6, 25 °C): δ = 0.0 (ν1/2 ≈ 450 Hz) ppm.
31P{1H} NMR (243 MHz, C6D6, 25 °C): δ = 59.9 (m) ppm. 31P
NMR (243 MHz, C6D6, 25 °C): δ = 59.9 (tm, 3JP,H = 32.1 Hz) ppm.
X-ray
Crystal
Structure
Analysis
of
7:
Formula
C32H26BF10PS·3C6H6, Mr
=
908.69, colorless crystal
0.25ϫ0.18ϫ0.07 mm, a = 11.3489(3) Å, b = 14.3452(4) Å, c =
15.7940(4) Å, α = 106.725(5)°, β = 105.005(4)°, γ = 104.483(3)°, V
= 2227.31(16) Å3, ρcalcd. = 1.355 gcm–3, μ = 1.652 mm–1, empirical
absorption correction (0.683ՅTՅ0.893), Z = 2, triclinic, space
1
NMR Spectroscopic Data of 8: H NMR (600 MHz, C6D6, 25 °C):
¯
δ = 7.31 (dt, 1JP,H = 482.4, 3JH,H = 7.4 Hz, 1 H, PH), 6.37 (d, 4JP,H
= 4.2 Hz, 4 H, m-Mes), 3.02 (m, 2 H, PCH2), 2.00 (s, 12 H, o-
group P1 (no. 2), λ = 1.54178 Å, T = 223(2) K, ω and φ scans,
27740 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1, 7676
independent (Rint = 0.055) and 6104 observed reflections [IՆ2σ(I)],
538 refined parameters, R = 0.062, wR2 = 0.178, max./min. residual
electron density 0.44/–0.41 eÅ–3, hydrogen atoms calculated and
refined as riding atoms.
CH3Mes), 1.85 (s, 6 H, p-CH3Mes), 1.79 (m, 2 H, BCH2) ppm.
1
13C{1H} NMR (151 MHz, C6D6, 25 °C): δ = 148.4 (dm, JF,C
≈
=
241 Hz, o-C6F5), 145.2 (d, JP,C = 2.5 Hz, p-Mes), 143.1 (d, 2JP,C
4
1
9.7 Hz, o-Mes), 139.1 (dm, JF,C ≈ 256 Hz, p-C6F5), 137.4 (dm,
1JF,C ≈ 249 Hz, m-C6F5), 131.6 (d, JP,C = 10.7 Hz, m-Mes), 124.5
3
Reaction of 4 with Air To Yield 6: A mixture of dimesityl(vinyl)-
phosphane (167 mg, 0.56 mmol) and bis(pentafluorophenyl)borane
(195 mg, 0.56 mmol, 1.0 equiv.) in n-pentane (15 mL) was stirred
for 15 min. Thereafter the flask was opened, and the reaction mix-
ture was stirred at room temperature for 30 min. A white solid pre-
cipitated, which was isolated by cannula filtration and dried in
vacuo to yield 6 (32%, 0.18 mmol, 119 mg). Crystals of 6 suitable
for an X-ray crystal structure analysis were obtained from a solu-
tion of 6 in cyclohexane at room temperature. Decomp. 133 °C.
1
1
(br., i-C6F5), 113.1 (d, JP,C = 79.0 Hz, i-Mes), 23.8 (d, JP,C
=
39.1 Hz, PCH2), 22.2 (br., BCH2), 21.7 (d, JP,C = 6.7 Hz, o-
CH3Mes), 20.8 (p-CH3Mes) ppm. 19F NMR (564 MHz, C6D6,
25 °C): δ = –132.5 (m, 2 F, o-C6F5), –160.7 (t, JF,F = 20.8 Hz, 1 F,
p-C6F5), –165.2 (m, 2 F, m-C6F5) [Δδ19Fm,p = 4.5] ppm. 11B{1H}
NMR (192 MHz, C6D6, 25 °C): δ = –2.5 (ν1/2 ≈ 750 Hz) ppm.
31P{1H} NMR (243 MHz, C6D6, 25 °C): δ = –5.5 (m) ppm. 31P
3
1
NMR (243 MHz, C6D6, 25 °C): δ = –5.5 (d, JP,H ≈ 481 Hz) ppm.
4
X-ray Crystal Structure Analysis of 8: C32H27BClF10P·CH2Cl2, Mr
= 763.69, colorless crystal 0.27ϫ0.17ϫ0.05 mm, a = 11.8395(2) Å,
b = 13.8203(3) Å, c = 14.0288(3) Å, α = 116.672(1)°, β = 94.135(1)°,
1H NMR (300 MHz, C6D6, 27 °C): δ = 6.39 (d, JP,H = 4.4 Hz, 2
H, m-Mes), 2.42 (m, 1 H, PCH2), 2.09 (s, 6 H, o-CH3Mes), 1.84 (s,
3 H, p-CH3Mes), not observed (BCH2) ppm. 19F NMR (282 MHz,
4
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Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I20288
/KAP1
Date: 27-06-12 09:44:38
Pages: 7
Halogen Addition to a Frustrated Lewis Pair
C6D6, 27 °C): δ = –133.8 (m, 2 F, o-C6F5), –159.3 (t, JF,F = 20.8 Hz,
1 F, p-C6F5), –164.4 (m, 2 F, m-C6F5) [Δδ19Fm,p = 5.1] ppm.
11B{1H} NMR (96 MHz, C6D6, 27 °C): δ = 4.5 (ν1/2 ≈ 600 Hz)
vacuo, and the residue was dried in vacuo to yield 8 as a white
powder (87%, 0.087 mmol, 59.0 mg). Crystals suitable for X-ray
crystal structure analysis were grown by slow concentration of a
ppm. 31P{1H} NMR (122 MHz, C6D6, 27 °C): δ = 80.0 (ν1/2 ≈ 4 Hz) solution of 8 in dichloromethane at –40 °C. The cell parameters are
ppm. 31P NMR (122 MHz, C6D6, 27 °C): δ = 80.0 (t, 2JP,H or 3JP,H equivalent to those described for compound 8 above. M.p. 185 °C.
= 21 Hz) ppm.
C32H27BClF10P (678.8): calcd. C 56.62, H 4.01; found C 56.66.13,
H 3.48.
X-ray Crystal Structure Analysis of 6: C32H26BF10OP, Mr = 658.31,
colorless crystal 0.30ϫ0.20ϫ0.20 mm, a = 11.0902(3) Å, b =
14.4816(5) Å,
Supporting Information (see footnote on the first page of this arti-
cle): Experimental details and structural data of compounds 5–9.
c
=
18.7149(6) Å,
β
=
100.871(2)°,
V
=
2951.75(16) Å3, ρcalcd. = 1.481 gcm–3, μ = 1.640 mm–1, empirical
absorption correction (0.639ՅTՅ0.735), Z = 4, monoclinic, space
group P21/n (no. 14), λ = 1.54178 Å, T = 223(2) K, ω and φ scans,
27334 reflections collected (Ϯh, Ϯk, Ϯl), [(sinθ)/λ] = 0.60 Å–1, 5225
independent (Rint = 0.040) and 4703 observed reflections [IՆ2σ(I)],
412 refined parameters, R = 0.044, wR2 = 0.119, max./min. residual
electron density 0.28/–0.25 eÅ–3, hydrogen atoms calculated and
refined as riding atoms.
Acknowledgments
Financial support from the Deutsche Forschungsgemeinschaft is
gratefully acknowledged.
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Reaction of 4 with Bromine To Yield 9: A mixture of dimesityl-
(vinyl)phosphane (40.0 mg, 0.135 mmol) and bis(pentafluoro-
phenyl)borane (46.7 mg, 0.135 mmol, 1.0 equiv.) was dissolved in
n-pentane (3 mL) and stirred for 10 min. Then bromine (excess
amount) was added to the yellow solution of 4 and a change of
color to dark brown was observed. After 2 d of stirring, a light
yellow solid began to precipitate, which was isolated after 5 d by
cannula filtration, washed with n-pentane (3ϫ4 mL), and dried in
vacuo to yield compound 9 as a light yellow powder (84%,
0.114 mmol, 91.3 mg). Crystals of 9 suitable for an X-ray crystal
structure analysis were grown by slow concentration of a solution
of 9 in deuterated benzene at room temperature. M.p. 141 °C.
C32H26BBr2F10P (802.1): calcd. C 47.92, H 3.27; found C 48.40, H
4
3.64. 1H NMR (500 MHz, C6D6, 26 °C): δ = 6.33 (d, JP,H
=
5.5 Hz, 2 H, m-Mes), 3.69 (m, 1 H, PCH2), 1.94 (s, 6 H, o-CH3Mes),
1.90 (m, 1 H, BCH2), 1.80 (s, 3 H, p-CH3Mes) ppm. 13C{1H} NMR
1
(126 MHz, C6D6, 26 °C): δ = 148.4 (dm, JF,C ≈ 242 Hz, o-C6F5),
145.7 (d, 4JP,C = 3.1 Hz, p-Mes), 141.6 (d, 2JP,C = 11.9 Hz, o-Mes),
1
1
139.4 (dm, JF,C ≈ 241 Hz, p-C6F5), 137.5 (dm, JF,C ≈ 244 Hz, m-
3
C6F5), 132.9 (d, JP,C = 12.8 Hz, m-Mes), 123.9 (br., i-C6F5), 119.5
(d, JP,C = 70.1 Hz, i-Mes), 39.7 (d, JP,C = 28.5 Hz, PCH2), 23.3
1
1
3
5
(d, JP,C = 4.8 Hz, o-CH3Mes), 21.1 (br., BCH2), 20.7 (d, JP,C
=
1.6 Hz, p-CH3Mes) ppm. 19F NMR (470 MHz, C6D6, 26 °C): δ =
–131.4 (m, 2 F, o-C6F5), –160.6 (t, JF,F = 20.9 Hz, 1 F, p-C6F5),
–165.2 (m, 2 F, m-C6F5) [Δδ19Fm,p = 4.6] ppm. 11B{1H} NMR
(96 MHz, C6D6, 25 °C): δ = –3.7 (ν1/2 ≈ 646 Hz) ppm. 31P{1H}
NMR (202 MHz, C6D6, 26 °C): δ = 62.4 (ν1/2 ≈ 12 Hz) ppm.
X-ray Crystal Structure Analysis of 9: C35H29BBr2F10P, Mr
841.18, colorless crystal 0.30ϫ0.27ϫ0.15 mm, a = 14.4911(4) Å,
8.5962(2) Å, 28.6984(7) Å, 101.331(2)°, V =
=
b
=
c
=
β
=
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3505.23(15) Å3, ρcalcd. = 1.594 gcm–3, μ = 4.070 mm–1, empirical
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independent (Rint = 0.040) and 5694 observed reflections [IՆ2σ(I)],
448 refined parameters, R = 0.036, wR2 = 0.097, max./min. residual
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dimesityl(vinyl)phosphane (30.0 mg, 0.101 mmol) and bis(pen-
tafluorophenyl)borane (35.0 mg, 0.101 mmol, 1.0 equiv.) was dis-
solved in benzene (3 mL) and stirred for 10 min. Then hydrogen
chloride (2.0 m in diethyl ether, 51 μL, 0.101 mmol, 1.0 equiv.) was
added to the yellow solution, and the solution immediately became
colorless. After stirring overnight, all volatiles were removed in
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Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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Job/Unit: I20288
/KAP1
Date: 27-06-12 09:44:38
Pages: 7
S. Frömel, R. Fröhlich, C. G. Daniliuc, G. Kehr, G. Erker
FULL PAPER
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Received: March 21, 2012
Published Online: ᭿
6
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Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I20288
/KAP1
Date: 27-06-12 09:44:38
Pages: 7
Halogen Addition to a Frustrated Lewis Pair
Halogen Addition
S. Frömel, R. Fröhlich, C. G. Daniliuc,
G. Kehr, G. Erker* ............................ 1–7
Halogen Addition to a Frustrated Lewis
Pair
The reactive frustrated Lewis pair A reacts
with thionyl chloride and halogens to yield
the zwitterionic X+/X– addition products B
and C, respectively.
Keywords: Frustrated Lewis pairs / Phos-
phorus / Boron / Halogens / Zwitterions
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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7