Through-space J(P,P) and J(P,F) spin-spin coupling in C1- symmetric biaryl diphosphanes

Article abstract of DOI:10.1002/ejic.201100428

The first simultaneous ³¹P,³¹P and ³¹P,¹⁹F solution-phase through-space nuclear spin-spin coupling in biphenyl derivatives is reported. The magnitudes of the coupling constants are in the range 5.3-28.7 and 2.3-

Full text of DOI:10.1002/ejic.201100428

FULL PAPER
DOI: 10.1002/ejic.201100428
Through-Space J(P,P) and J(P,F) Spin–Spin Coupling in C1-Symmetric Biaryl
Diphosphanes
Laurence Bonnafoux,[a] Ludger Ernst,*[b] Frédéric R. Leroux,*[a] and Françoise Colobert[a]
Keywords: Biphenyl / Coupling / Phosphanes / Fluorine / NMR spectroscopy
The first simultaneous 31P,31P and 31P,19F solution-phase 1H{31P}-decoupling and iterative bandshape analysis] were
through-space nuclear spin–spin coupling in biphenyl deriv-
atives is reported. The magnitudes of the coupling constants
are in the range 5.3–28.7 and 2.3–5.1 Hz, respectively. Their
observation became possible through access to a recently de-
veloped class of C1-symmetric biphenyl diphosphanes. We
used this to prepare a series of model compounds for the
study of the through-space couplings. Various 1D and 2D
techniques [COSY, NOESY, heteronuclear single quantum
coherence (HSQC), HMBC, HSCQ-TOCSY, selective
applied to assign the 1H, 13C, 19F and 31P NMR spectra as
completely as possible. X-ray structure determinations con-
firmed the structural assignments and afforded P···P dis-
tances and torsion angles in the solid state. No simple corre-
lation was found between the experimental J(31P,31P) values
in solution and the relevant geometric parameters (P···P dis-
tance and torsional angle between the phosphorus lone
pairs) in the solid state.
Introduction
Phosphane-based ligand research for catalysis is one of
the most fascinating and prolific areas of chemistry. Over
the last 60 years, intensive efforts have been devoted to the
synthesis of new phosphanes and to their application in co-
ordination chemistry.[1] Particular attention has been paid
to their use in catalysis and especially in asymmetric hydro-
genation.[2] In this context, an increasingly large number of
phosphane ligands has been developed and tested in transi-
tion metal-catalyzed reactions. In particular, the role of the
ligand backbone is one of the cornerstones of investigations
Scheme 1. From C2-symmetry to C1-symmetry in biaryl diphos-
phane ligands as exemplified for MeO-BIPHEP.
In the course of our NMR studies on these diphos-
in the field of ligand design. Thus, phosphorus substituents phanes, an unexpected variety of J(P,P) and, in some cases,
have been successively attached to various building blocks, J(P,F) through-space nuclear spin–spin couplings was ob-
such as tartaric acid derivatives, binaphthyl, biphenyl, ferro- served, which have not been previously reported. To date,
cenyl and heteroaromatic scaffolds, providing great struc- the observation of scalar through-space interactions has
tural diversity and leading to powerful ligands including been limited mainly to fluorine containing organic spe-
DIOP,[3] BINAP,[4] MeO-BIPHEP[5] and Josiphos.[6] cies,[8] with the through-space 19F,1H coupling observed by
Among these phosphanes, our group has recently reported Davis et al. in 1961 being the first example.[9] Through-
the synthesis and catalytic properties of new C1-symmetric space coupling with at least one fluorine atom is quite com-
biaryl diphosphane ligands.[7] These studies have high- mon. More recent experimental studies have been published
lighted their efficiency in benchmark asymmetric hydrogen- by Ernst and Mallory et al.,[8a,8i] and theoretical investi-
ation reactions in comparison to classical C2-symmetric bi- gations by Peralta and Arnold et al.[8j,8k]
aryl diphosphanes, such as BINAP and MeO-BIPHEP
(Scheme 1).
Although through-space coupling involving one phos-
phorus nucleus is described in the literature, this phenome-
non has been less systematically studied and has phospho-
rus exclusively in the +III oxidation state.[10] For example,
Odorisio et al.[11] and Goddard et al.[12] reported the 31P,1H
coupling through space in 12H-dibenzo[d,g][1,3,2]dioxa-
phosphocinenes. In 1990, Pascal Jr. et al.[13] observed the
first 31P,13C spin–spin coupling through space in cy-
clophanes. Pye et al. reported an analogous through-space
coupling in 4,12-bis(diphenylphosphanyl)[2.2]paracyclo-
phane.[14] Pastor et al. studied numerous bis(phosphites)
[a] Laboratoire de Stéréochimie (UMR CNRS 7509), CNRS/Uni-
versity of Strasbourg, ECPM,
25 Rue Becquerel, 67087 Strasbourg Cedex 02, France
E-mail: frederic.leroux@unistra.fr
[b] Department of Chemistry, Technische Universität
Braunschweig
Hagenring 30, 38106 Braunschweig, Germany
E-mail: l.ernst@tu-bs.de
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100428.
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L. Bonnafoux, L. Ernst, F. R. Leroux, F. Colobert
FULL PAPER
and observed 31P,31P coupling through space.[15] Sawamura the value of J(P,P) is strongly dependent on the nature of
et al. also observed a large 31P,31P coupling of 22.0 Hz in the ortho-substituent R and varies from 11.4 when R = Ph
chiral bis[1-(diarylphosphanyl)ethyl]-1,1ЈЈ-biferrocene be- (5) to 28.7 Hz when R = –OCF2O– (8). The most reason-
tween the two P nuclei separated by seven bonds.[16] On the able explanation for these NMR patterns is the existence of
other hand, Hillebrand et al. claimed a 31P,31P coupling of a through-space coupling (nuclear spin–spin coupling
27.3 Hz to be present in 4,5-bis(diphenylphosphanyl)- through nonbonded interactions) of the phosphorus atoms.
xanthene.[17] Similarly, Hierso et al. reported 31P,31P cou- But surprisingly, for bis(diphenylphosphanyl)biphenyls sub-
pling through space in tetraphosphane ferrocenyl deriva- stituted by an N(CH3)2 (6) or OCF3 (7) group, the phos-
tives[18] and suggested, in analogy to Mallory’s theory, a phorus nuclei appear as one singlet in the 31P NMR spec-
lone-pair overlap model for this type of coupling. Matt et trum, see below for an explanation.
al. reported 31P,31P coupling through space in diphosphane
calixarenes where the phosphorus atoms are ten bonds
apart,[19] and, finally, extremely large through-space 31P,31P
Requirements for Through-Space Nuclear Spin–Spin
Coupling
couplings of about 240 Hz were observed in a series of di-
bridged calix[4]arene bisphosphites.[20]
In contrast, 31P,19F coupling through space is less often
Most notably, this phenomenon was studied and ana-
described in the literature than 31P,1H or 31P,13C cou- lyzed by Mallory et al. who established a qualitative model
plings.[21] 31P,19F coupling through space has been mainly to explain through-space coupling.[8b,8c] Some prerequisites
observed in 2-(trifluoromethyl)phenylphosphanes.[22]
are necessary to observe through-space coupling in NMR:
(i) Two lone-pair atomic orbitals of crowded elements
(phosphorus, nitrogen or fluorine) must be available.
(ii) They have to be in close proximity to permit overlap,
which can be achieved by rigid backbone architecture.
(iii) Homonuclear through-space coupling can only be ob-
served between anisochronous nuclei, i.e. in an unsymmetri-
cal system or by making use of the 13C satellites in an other-
wise symmetrical system. Due to the large one-bond 19F,13C
coupling constants, the observation of J(F,F) in the latter
case is relatively easy but it is difficult to observe J(P,P) in
symmetrical cases containing isochronous PIII nuclei be-
cause one-bond 31PIII,13C couplings are relatively small
(generally Ͻ 15 Hz) and of similar magnitude as the corre-
sponding two- and three-bond couplings. Additional diffi-
culty arises when the PIII nucleus is connected to three non-
equivalent 13C nuclei and experiences three 1J(P,C) cou-
plings of a similar size. Hence, the observation of through-
space coupling involving two phosphorus(III) atoms is
rare.[15–20] Particularly in the field of biaryl-based diphos-
phanes, no through-space P,P coupling has been reported
so far. In this context, it is of note that attempts to extract
J(P,P) solely from the splitting patterns of 13C NMR signals
of diphosphanes [i.e. extracting J(A,AЈ) or J(A,B) from the
X parts of AAЈX or ABX spin systems] give unreliable re-
sults because the desired coupling constant is insufficiently
correlated with the X frequencies.[17]
Results and Discussion
31P31P Coupling in Bis(diphenylphosphanyl)biphenyls
We synthesized the first C1-MeO-BIPHEP analogue (1)
and showed its efficiency in asymmetric hydrogenation in
2007 (Figure 1).[7b–7f] In this molecule, the two phosphorus
groups are nonequivalent due to the C1-symmetry of the
biphenyl backbone. When we analyzed its proton-decou-
pled 31P NMR spectrum, instead of observing two singlets
as expected, we were surprised to see that the nonequivalent
phosphorus nuclei appeared as doublets with a coupling
constant of 5J(P,P) = 18.3 Hz. First we assumed that
through-bond coupling was responsible for this multiplicity
as five bonds separate the phosphorus atoms.
Figure 1. C1-symmetric bis(diphenylphosphanyl)biphenyls.
In 2000, Mallory et al. quantified the through-space cou-
However, we recently prepared a series of analogues car- pling interaction for a family of 1,8-difluoronaphthalenes
rying various substituents at the ortho position instead of a through an exponential relationship between ab initio cal-
methoxy group. Our goal was to modify the steric and elec- culated intramolecular F···F distances and the observed
tronic properties of the biaryl backbone and to investigate J(F,F) values.[8a] Earlier, for difluorinated cyclophanes,
the influence of these parameters on the catalytic activity. Ernst and Ibrom derived a similar exponential correlation
Thus, eight new bis(diphenylphosphanyl)biphenyl com- between through-space J(F,F) and nonbonded F···F dis-
pounds with R = CH3 (2), Cl (3), OCH2O (4), Ph (5), tances calculated by molecular mechanical methods.[8i] The
N(CH3)2 (6), OCF3 (7), OCF2O (8) and OCF2CF2O (9) key feature of Mallory’s theory is that the magnitude of the
were synthesized (Figure 1).
through-space coupling constant depends on the degree of
In most of these compounds, the phosphorus groups also lone-pair orbital overlap.[10c] For a series of fluoro-substi-
appear as two doublets in the 31P NMR spectra measured tuted aromatic 15N-enriched oximes the authors also dem-
from CDCl3 solutions at room temperature. We noticed that onstrated that changing the angle between the two orbitals
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Through-Space J(P,P) and J(P,F) Spin–Spin Coupling in Biaryl Diphosphanes
involved in the proximate J(19F,15N) coupling affects its spired that we were only dealing with slightly temperature
size.[8b] In 2004, Hierso et al. successfully extended Mallo- dependent chemical shifts, which are equal at room tem-
ry’s model to 31P,31P through-space spin–spin interactions perature and therefore prevent signal splitting. In fact, when
in organometallic species.[18,23]
the solvent was changed from CDCl3 to CD2Cl2, both com-
pounds showed anisochronous 31P nuclei at room tempera-
ture, albeit with small chemical shift differences of 0.1 for
6 and 0.2 ppm for 7. The J(P,P) values were found to be 5.3
and 22.4 Hz for 6 and 7, respectively.
Discussion of the 31P,31P Coupling in
Bis(diphenylphosphanyl)biphenyls
In order to prove that the spin information from 31P to
31P is transmitted through space and not through the five
bonds of the biaryl backbone in the molecules mentioned
above several investigations were carried out.
Through-Space 31P,19F Coupling in Fluorinated
Bis(diphenylphosphanyl)biphenyls
First, the existence of coupling between the two phos-
phorus nuclei follows from the identical coupling constant
in the two 31P signals and from the fact that no other 31P
resonances are present. Confirmation was obtained from
2D 31P,31P COSY experiments, which showed the expected
cross peaks between the two 31P chemical shifts. The P,P
coupling of 22.5 Hz in 3, for example, might in principle
arise from through-bond interactions but its magnitude is
abnormally large for a five-bond coupling, particularly as
the biphenyl system is expected to be twisted about the C1–
C1Ј bond, which severely dampens the conjugation between
the phenyl rings. When we converted the diphosphanes 1–5
into their corresponding bis(phosphane oxides) and bis-
(phosphane selenides), the P,P couplings disappeared as the
lone pair electrons are no longer available for through-space
interactions but are involved in P–O or P–Se “double”
bonds (Table 1).
In diphosphane 7 (R = OCF3) only a barely resolved
31P,19F coupling of 1.4 Hz could be observed between the
trifluoromethoxy group and the phosphorus nucleus of the
PPh2 substituent at C2Ј. The OCF3 group probably prefers
a conformation in which it can avoid the region of steric
hindrance. In order to enforce 31P,19F interactions we de-
vised the bis(diphenylphosphanyl)biphenyls 8 and 9, substi-
tuted with rigid, cyclic fluorinated ether substituents (Fig-
ure 2). One would expect that there is at least one fluorine
atom that cannot evade close contact with the P2Ј atom due
to the restricted mobility about the C6–O bond in these
compounds (Figure 2).
Table 1. 31P NMR signals of the corresponding selenides and
oxides.
Figure 2. C1-symmetric bis(diphenylphosphanyl)biphenyls carrying
a fluorinated ether substituent.
Indeed, the presumed 31P,19F through-space coupling in
8 was larger than that in 7 (2.3 vs. 1.4 Hz). In compound 9
the more deshielded phosphorus atom is coupled to two
fluorine nuclei (5.1 and 2.5 Hz, see Table 2). This is dis-
cussed further below. In the corresponding bis(dicyclohex-
ylphosphanyl)biphenyls, 10 and 11, no 31P,19F coupling was
detected because the lines were broad, both in the 31P and
19F spectra.
In order to further substantiate the notion that the
31P,19F coupling is transmitted through space, we prepared
two cyclic compounds with only one phosphorus atom each
We have thus proved that the observed 31P,31P coupling in which through-space coupling cannot occur, namely the
is transmitted through space in 1–5. This also applies to the phosphafluorene derivatives 12 and 13. In these compounds
remaining compounds. However, we still need to explain the phosphorus appears as a singlet at δ = –5.2 (12) and
why the two chemically nonequivalent phosphorus nuclei –7.8 ppm (13), see Table 2. The systems 8/9 and 12/13 are
appear as a unique singlet in the bis(diphenylphosphanyl)- comparable with respect to the arrangement of the F2C–O–
biphenyls 6 [R = N(CH3)2] and 7 (R = OCF3). When we C6–C1–C2–P sequence of atoms (apart from the nonrota-
lowered the temperature, the 31P signals of both 6 and 7 tional C2–P bonds in 12/13). Hence, the absence of P,F cou-
decoalesced and became AB spectra. At first glance, this pling in 12/13 as opposed to 8/9 gives support to our hy-
gave the impression of slowing some conformational pro- pothesis that the P,F couplings observed in 8/9 are through-
cess. However, little line broadening occurred and it tran- space couplings involving P2Ј and not through-bond cou-
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L. Bonnafoux, L. Ernst, F. R. Leroux, F. Colobert
FULL PAPER
Table 2. 31P NMR of 8, 9, 12 and 13 in CDCl3 at room tempera- the 3.1 Hz coupling in the dd of HZ originates from PG,
ture.
J(PG,HZ) = 3.1 Hz, δP = –14.1 ppm, and PG is the phospho-
rus atom bound to C2. On the other hand, the 4.1 Hz cou-
pling of HX is J(P2Ј,H6Ј), which follows from selective de-
coupling of the signal at δP = –12.7 ppm.
1
Figure 4. H NMR spectrum of 8 (600 MHz, CDCl3).
Table 3. NMR data of 8.
Signal
Assignment δ [ppm]
Multiplicity[a] J [Hz]
plings involving P2. Experimentally this was proved as de-
scribed below.
PA
P2Ј
P2
Fanti
Fsyn
H4
H6Ј
H3
–12.7
–14.1
–49.73
–50.14
6.95
6.85
6.78
dd
d
d
dd
d
ddd
dd
28.7, 2.3
28.7
95.4
95.4, 2.3
8.2
7.6, 4.1, 1.3
8.2, 3.1
PG
FK
FQ
HT
HX
HZ
In addition, the 31P NMR spectrum of bis(diphenylphos-
phanyl)biphenyl 9 (R = OCF2CF2O) was recorded in C6D6
and in [D6]DMSO at two different concentrations (c =
0.33 and 3.3 mg/mL) and at 100 °C in C2D2Cl4. The multi-
plicities stayed the same as in CDCl3 solution, which dem-
onstrates that the P,F couplings are not solvent, concentra-
tion or temperature dependent.
7
7
[a] Multiplicities of 19F and 31P signals refer to 1H-decoupled spec-
tra.
In order to elucidate the spin coupling pattern of 8 in
more detail and to prove that the 31P nucleus involved in
spin coupling with 19F is the phosphorus atom bound to
C2Ј and not that bound to C2, we carried out additional
31P and 19F NMR experiments. The spin system under dis-
cussion is of the type AGKQTXZ (A, G = 31P; K, Q = 19F;
In the 31P{1H}cpd spectrum of 8, PA (δP = –12.7 ppm)
and PG (δP = –14.1 ppm) have a mutual coupling constant
J(P,P) of 28.7 Hz. The signal of PA shows a doublet split-
ting of 2.3 Hz (Figure 5a) caused by one of the fluorine
nuclei, FQ. PA is P2Ј as shown above, so the observed
J(PA,FQ) coupling of 2.3 Hz involves P2Ј and not P2. It can
be taken for granted that this coupling operates more or
less exclusively through space because the intervening seven
chemical bonds have neither suitable geometry nor suitable
electronic characteristics (two consecutive saturated centres,
C7 and O6) for long-range through-bond coupling.
Furthermore, it is likely that P2Ј couples to the fluorine
atom on the same side of the benzodioxole plane, FQ in 8,
which is the fluorine atom in front of the plane in the dia-
gram (Figure 3). If the J(P,F) coupling under discussion in-
volved P2 instead of P2Ј, one would expect very similar
couplings between P2 and both 19F nuclei because of the
planar nature of the benzodioxole ring system.
1
T, X, Z = H, Figure 3).
Figure 3. AGKQTXZ spin system in compound 8.
1
In the otherwise complicated H NMR spectrum, three
The 19F nuclei at δF = –49.73 (FK) and –50.14 ppm (FQ)
well resolved and separated signals were observed (Figure 4, mutually couple with J(F,F) = 95.4 Hz and FQ again shows
Table 3). Protons HT and HZ with their common coupling a J(PA,FQ) coupling of 2.3 Hz (Figure 5b). The chemical
of 8.2 Hz can only be H3 and H4 with HZ being H3 because nonequivalence of the two 19F nuclei indicates that internal
3
of its J(P,HZ) = 3.1 Hz coupling to phosphorus and HT rotation about the C1–C1Ј bond is slow on the NMR time
being H4 with 4J(P,HT) ≈ 0 Hz. This is more likely than the scale at room temperature. Incidentally, slow rotation about
1
reverse assignment and was supported by H,13C HMBC. C1–C1Ј applies to all the bis(diphenylphosphanyl)biphenyls
1
Selective H{31P} continuous wave decoupling showed that in this study deduced from the appearance of four sets of
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Through-Space J(P,P) and J(P,F) Spin–Spin Coupling in Biaryl Diphosphanes
Table 4. NMR data of 9.
Signal Assignment δ [ppm]
Multiplicity J [Hz]
PA
P2Ј
P2
Fanti
–13.9
–14.7
–90.44
–91.26
–92.72
–93.07
7.05
ddd
d
24.6, 5.1, 2.5
24.6
PG
FK
FL
FM
FN
HT
HX
HZ
7
ddd
dddd
dddd
ddd
d
148.5, 18.4, 10.1
147.3, 18.9, 10.1, 2.5
148.5, 18.9, 5.1, 3.8
147.3, 18.4, 3.8
8.5
F
F
syn8
syn7
Fanti
H4
H3
H6Ј
8
6.86
6.73
dd
ddd
8.5, 2.6
7.6, 4.1, 1.3
of the drawing of 9 in Figure 6 and are bound to C7 and
C8, respectively (Figure 7, Table 4). We assign the fluorine
atom with the 5.1 Hz coupling to FM (closer to P2Ј) and
that with the 2.5 Hz coupling to FL (further from P2Ј). The
3
dihedral angle dependence of J(F,F) is complex.[24] Hence,
the cis orientation of FL and FM cannot be derived simply
3
from the size of J(F,F).
Figure 5. 1H-decoupled NMR spectra of 8 in CDCl3, (a) 31P at
162 MHz, (b) 19F at 376 MHz. The high-frequency 31P signal and
the low-frequency 19F signal show a 31P,19F coupling of 2.3 Hz.
phenyl signals in each 13C NMR spectrum, i.e. all PPh2
groups have diastereotopic phenyl substituents at room
temperature.
A similar study was carried out with diphosphane 9,
which was considered as an AGKLMNTXZ spin system
(A, G = 31P; K, L, M, N = 19F and T, X, Z = 1H, Figure 6).
Figure 7. Experimental (bottom) and calculated (top) 376.5 MHz
19F NMR spectra of 9. Fluorine signals F–L and F–M show 31P-
19F couplings of 2.5 and 5.1 Hz, respectively.
As far as the size of our through-space coupling con-
stants is concerned, a J(P,P) of up to 28.7 Hz may not seem
overly large when compared, for example, with the biggest
through-space J(F,F) of 110.1 Hz that we reported pre-
viously.[8i] A proper comparison, however, should refer to
the reduced coupling constants K(X,Y) = 4π2J(X,Y)/
Figure 6. AGKLMNTXZ system in diphosphane 9.
In the complex 1H NMR spectrum of 9 three signals (hγXγY), which take into account the magnetogyric ratios of
were assigned (Table 4). Selective H{13Pcw} decoupling, as the coupled nuclei. A J(P,P) value of 28.7 Hz thus translates
1
in the case of 8, allowed the assignment of the 31P reso- to a K(P,P) value of 1.46ϫ1020 T2 J–1 (or kgA–2 s–2 m–2),
nances: PA at δP = –13.9 ppm corresponds to P2Ј and PG at whereas a J(F,F) value of 110.1 Hz corresponds to K(F,F)
δP = –14.7 ppm to P2; PA shows two couplings to 19F of 5.1 = 1.03ϫ1020 T2 J–1. Hence there is more significance to the
and 2.5 Hz.
J(P,P) than to the J(F,F) value. Our largest J(P,F) coupling
In the four-spin 19F subsystem, all fluorine atoms are of 5.1 Hz corresponds to a K(P,F) value of just 1.11ϫ1019
chemically nonequivalent. Thus, there is a slow rotation T2 J–1.
about C1–C1Ј. Two fluorine atoms are coupled to the same
There are two very similar chemical shifts of the mutually
phosphorus atom, namely P2Ј (δP = –13.9 ppm), with J = coupled 31P nuclei in the 13C NMR spectra of bis(phos-
5.1 and 2.5 Hz, respectively. The 19F spin system was ana- phanes) 6 and 7, which makes their 13C NMR spectra sec-
lyzed by iterative full line-shape fitting. The mutual cou- ond order: each 13C signal represents the X part of an ABX
pling of the fluorine atoms coupled to 31P is 18.9 Hz. It is spectrum. When two lines of these X parts are distinctly
likely that both are syn with respect to P2Ј, i.e. cis to each more intense than the remaining (two or four) lines, their
other. They are both oriented towards the front of the plane frequency difference is readily recognized as the sum
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L. Bonnafoux, L. Ernst, F. R. Leroux, F. Colobert
FULL PAPER
|J(A,X) + J(B,X)|. As the approximate size of J(A,X) and/ in solution was found, we note that the smallest coupling
or J(B,X) can be estimated from the values in the first order constant of 5.3 Hz in the NMe2 derivative 6 coincides with
spectra of the other bis(diphenylphosphanyl) compounds, the largest P···P distance.
this allows the deduction of the relative signs of J(A,X) and
J(B,X) in these cases. Consider, for example, the C1 signal
3
in 7 where |∑J(P,C)| = |2J(P2,C1) + J(P2Ј,C1)| = 39.7 Hz.
2
The individual magnitudes of J(P2,C1) in 1–3 are 30.8–
3
32.5 and those of J(P2Ј,C1) are 6.5–7.1 Hz. Hence these
two types of coupling must be of equal sign in order to give
a sum of ca. 40 Hz. Were they of opposite sign, their sum
would be 24–26 Hz. From the literature 2J(P,C-ortho) is
3
positive in triphenylphosphane.[25] Hence J(P2Ј,C1) in this
series of compounds must also be positive. From the C6Ј
signal of 7, |∑J(P,C)| = 9.6 Hz with 3J(P2Ј,C6Ј) = 6.2–
6.3 and 4J(P2,C6Ј) = 3.1–3.8 Hz in 1–3. These two cou-
plings must therefore also have the same sign. With 3J(P,C-
meta) being positive in triphenylphosphane,[25] 4J(P2,C6Ј) is
Figure 8. Molecular structure of compound 4 in the solid state.
also positive in our compounds. The situation is less clear
cut for the P,C couplings involved in C2 and C2Ј because
1
of the varying magnitude of J(P,C) and the small size of
4J(P,C).
Applying Mallory’s model of the transmission of
through-space coupling by overlap of the lone-pair electron
orbitals to our biphenyl diphosphanes, we searched for a
simple correlation between the observed 31P,31P coupling
constants and the geometries of those compounds for which
X-ray structure determinations had been carried out (4, 6,
8, 9). A simple exponential of the type J(P,P) = aϫexp-
[–bϫd(P···P)], where the P···P distance, d(P···P), is the only
geometric parameter on which the coupling depends, was
Figure 9. Molecular structure of compound 6 in the solid state.
far from successful in reproducing the experimental find-
ings, in contrast to our previously derived exponential de-
pendence of J(F,F) on d(F···F).[25] Multiplying the ex-
ponential by an angular function such as cosΘ(lp–P–P–lp)
or the square thereof, where Θ is the dihedral angle between
the phosphorus lone pairs, did not improve the result. Thus,
for the time being, we tentatively conclude that the X-ray
geometries do not reflect the geometries well, particularly
the conformations, of the biphenyl diphosphanes in solu-
tion.
Figure 10. Molecular structure of compound 8 in the solid state.
Crystallographic Studies
Single-crystal X-ray analyses have been carried out for 4,
6, 8 and 9.[26] Perspective ORTEP diagrams including the
atomic numbering schemes are provided in Figures 8, 9, 10
and 11. The torsion angles P–C–C–P between the planes of
the two Ph ring of the biphenyl system, Θ, are 110.35 (4),
111.03 (6), 110.36 (8) and 102.28° (9). Thus, due to trisub-
stitution, the two phosphane substituents show an in-
creased distance compared to a typical C2-symmetric bis(di-
phenylphosphanyl)biphenyl molecule, such as BIPHEMP
(88.7°).[27] The P···P distance in the OCH2O derivative 4 is
4.574, for NMe2 (6) 4.696, OCF2O (8) 4.414 and
OCF2CF2O (9) 4.455 Å. Although no correlation between
the solid-state structures and the J(P,P) coupling constants Figure 11. Molecular structure of compound 9 in the solid state.
3392
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 3387–3397

Through-Space J(P,P) and J(P,F) Spin–Spin Coupling in Biaryl Diphosphanes
purified by column chromatography on silica gel using cyclohexane
Conclusions
as the eluent to separate phosphafluorene and diphosphane from
triphenylphosphane. Triturating from dichloromethane afforded
pure (6-methoxybiphenyl-2,2Ј-diyl)bis(diphenylphosphane) (1;
17%) as a colourless powder. M.p. 227–228 °C (dec.). 1H NMR
(600 MHz, CDCl3): δ = 7.33–7.19 (m, 18 H), 7.18–7.14 (m, 4 H),
7.08–7.03 (m, 2 H, o-dpp), 6.82 (ddm, J ≈ 7.5, 4.3, 1.4 Hz, 1 H,
H6Ј), 6.77 (dd, J = 8.3, 1.0 Hz, 1 H, H5), 6.66 (ddd, J = 7.7, 3.2,
1.0 Hz, 1 H, H3), 3.22 (s, 3 H, OCH3). 13C NMR (151 MHz,
CDCl3): δ = 157.1 (Cq, dd, J = 9.6, 2.0 Hz, C6), 143.9 (Cq, dd, J
= 33.3, 7.9 Hz, C1Ј), 138.39 (Cq, dd, J = 10.4, 1.3 Hz, C2), 138.38
(Cq, d, J = 13.1 Hz, i-dpp), 138.32 (Cq, d, J = 13.8 Hz, i-dpp),
137.57 (Cq, dd, J = 13.1, 0.8 Hz, i-dpp), 137.44 (Cq, dd, J = 13.0,
0.8 Hz, i-dpp), 137.2 (Cq, dd, J = 9.1, 1.3 Hz, C2Ј), 136.2 (Cq, dd,
J = 32.5, 7.1 Hz, C1), 134.6 (d, J = 2.4 Hz, C3Ј), 134.1 (CH, d, J
= 20.1 Hz, 2 C, o-dpp), 133.9 (CH, d, J = 19.9 Hz, 2 C, o-dpp),
133.349 (CH, dd, J = 18.8, 2.3 Hz, 2 C, o-dpp), 133.346 (CH, dd,
J = 18.9, 1.2 Hz, 2 C, o-dpp), 131.2 (CH, dd, J = 6.2, 3.8 Hz, C6Ј),
128.8 (CH, d, J = 1.1 Hz, C4), 128.18 (CH, d, J = 6.8 Hz, 2 C, m-
dpp), 128.15 (CH, d, J = 6.0 Hz, 2 C, m-dpp), 128.14 (CH, d, J =
5.6 Hz, 2 C, m-dpp), 127.97 (CH, d, J = 6.7 Hz, 2 C, m-dpp), 128.4,
128.3 (br.), 128.00, 127.92, 127.86 (CH, C5Ј and 4 p-dpp), 127.6
(CH, C4Ј), 126.0 (CH, d, J = 1.6 Hz, C3), 110.5 (CH, C5), 54.7
(OCH3). 31P NMR (121 MHz, CDCl3): δ = –13.6 (d), –14.0 (d, J
So far, studies of the transmission of nuclear spin–spin
coupling through space have focused on fluorine- and nitro-
gen-containing organic compounds. In this work, we pro-
vide experimental evidence for and numerical values of
through-space J(P,P) and J(P,F) coupling constants. We
have identified the first simultaneous through-space P,P-
and P,F-coupling in biphenyl derivatives and analyzed this
phenomenon by accurate NMR studies and X-ray crystal-
lographic analysis. The study of this uncommon NMR
coupling pattern became possible due to access to a new
class of C1-symmetric bis(diphenylphosphanyl)biphenyls.
Attempts to correlate the experimental through-space
J(P,P) coupling constants in solution with the geometries of
the compounds in the solid state were unsuccessful.
Experimental Section
General Consideration: All reactions and workup procedures were
performed under an inert atmosphere of argon using conventional
vacuum line and Schlenk techniques. Toluene and THF were dis-
tilled by heating with sodium benzophenone under argon. Starting
materials, if commercial, were purchased and used as received, pro-
vided that adequate checks (melting ranges, refractive indices and
gas chromatography) had confirmed the purity. Air- and moisture-
sensitive materials were stored in Schlenk tubes and were protected
by and handled under an atmosphere of argon, using appropriate
glassware. 1H and 13C NMR spectra were recorded at 400 and 600
and at 101 and 151 MHz, respectively. The instruments used were
a Bruker Avance II 600 with a TCI (1H, 13C, 15N) cryo probe head,
a Bruker DRX 400 with a QNP (1H, 13C, 19F, 31P) probe head and
a Bruker Avance III 400 spectrometer with a BBFO+ (1H, 19F,
15N–31P) probe head. Chemical shifts are reported in δ units (ppm)
and were measured relative to tetramethylsilane (δH = 0.00 ppm)
and CDCl3 (δC = 77.01 ppm). 19F and 31P chemical shifts were
referenced to the frequencies previously determined for CCl3F (δF
= 0.00 ppm) and ext. 85% H3PO4 (δP = 0.00 ppm), respectively, in
CDCl3. Assignment techniques used were DEPT-135, H,H-COSY,
H,H-NOESY, H,C-HSQC, H,C-HMBC, HSQC-TOCSY and se-
lective 1H{31P}-decoupling. In order to distinguish 31P,13C coupling
constants from small chemical differences in the 13C NMR spectra,
these spectra were recorded both at 151 and at 101 MHz. Abbrevi-
ations: i-dpp, o-dpp, m-dpp and p-dpp refer to the ipso-, ortho-,
meta-, and para-positions, respectively, of the diphenylphosphanyl
substituents. Iterative analysis of the 19F NMR spectrum of 9 was
carried out with Bruker’s WIN-DAISY software.[28]
= 18.3 Hz). MS(EI): m/z (%) = 535.1 (Ͻ 1) [M+], 459.1 (1) [M+
–
Ph], 351.1 (100) [M+ – PPh2], 337.1 (6) [M+ – PPh2–Me], 183.1 (42)
[M+ – PPh2–Me–2 Ph]. HRMS for C37H30OP2 [M + H]: calcd.
553.1845; found 553.1886.
(6-Methylbiphenyl-2,2Ј-diyl)bis(diphenylphosphane) (2): Prepared
from 2,2Ј-dibromo-6-methylbiphenyl. The crude product was puri-
fied by column chromatography on silica gel using cyclohexane as
the eluent to separate phosphafluorene and diphosphane from tri-
phenylphosphane. Crystallization from methanol afforded pure (6-
methylbiphenyl-2,2Ј-diyl)bis(diphenylphosphane) (2, 30%) as
colourless crystals. M.p. 181–182 °C. 1H NMR (600 MHz, CDCl3):
δ = 7.37–7.32 (m, 2 H, o-dpp), 7.31–7.12 (m, 20 H), 7.07 (m, 1 H,
H5Ј), 6.96 (tm, J ≈ 7 Hz, 2 H, o-dpp), 6.86 (ddd, J = 7.5, 3.5,
1.4 Hz, 1 H, H3), 6.61 (ca dddd, J = 7.6, 4.4, 1.3, 0.6 Hz, 1 H,
H6Ј), 1.68 ppm (s, 3 H, CH3). 13C NMR (151 MHz, CDCl3): δ =
146.41 (Cq, dd, J = 30.8, 6.5 Hz, C1 or C1Ј), 146.37 (Cq, dd, J =
32.4, 7.0 Hz, C1Ј or C1), 138.75 (Cq, d, J = 14.2 Hz, i-dpp), 137.63
(Cq, d, J = 13.0 Hz, i-dpp), 137.36 (Cq, dd, J = 9.8, 2.1 Hz, C2),
137.26 (Cq, dd, J = 13.4, 1.3 Hz, i-dpp), 137.08 (Cq, dd, J = 13.5,
1.5 Hz, i-dpp), 136.92 (Cq, dd, J = 10.0, 1.8 Hz, C2Ј), 136.92 (Cq,
dd, J = 6.0, 2.1 Hz, C6), 134.44 (CH, d, J = 21.0 Hz, 2 C, o-dpp),
134.43 (CH, d, J = 2.3 Hz, C3Ј), 134.24 (CH, d, J = 20.5 Hz, 2 C,
o-dpp), 133.40 (CH, dd, J = 18.4, 3.1 Hz, 2 C, o-dpp), 133.18 (CH,
dd, J = 18.6, 1.4 Hz, 2 C, o-dpp), 131.30 (CH, d, J = 1.4 Hz, C3),
130.65 (CH, dd, J = 6.2, 3.1 Hz, C6Ј), 130.39 (CH, C5), 128.55
(CH, p-dpp), 128.36 (CH, p-dpp), 128.32 (CH, C5Ј), 128.23 (CH,
d, J = 7.1 Hz, 2 C, m-dpp), 128.21 (CH, d, J = 5.9 Hz, 2 C, m-
dpp), 128.07 (CH, d, J = 5.7 Hz, 2 C, m-dpp), 128.06 (CH, d, J =
7.1 Hz, 2 C, m-dpp), 127.98 (CH, p-dpp), 127.72 (CH, p-dpp),
127.67 (CH, C4), 127.47 (CH, C4Ј), 20.58 ppm (t, J = 2.7 Hz,
CH3). 31P NMR (162 MHz, CDCl3): –12.8 (d), –14.6 ppm (d, J =
27.1 Hz). MS(EI): m/z (%) = 535.1 (Ͻ 1) [M+], 459.1 (1) [M+ – Ph],
351.1 (100) [M+ – PPh2], 337.1 (6) [M+ – PPh2–Me], 183.1 (42)
[M+ – PPh2–Me–2 Ph]. C32H30P2 (536.58): calcd. (%) C 82.82, H
5.64; found C 82.53, H 5.92.
General Synthetic Procedure: At 25 °C, butyllithium (2 equiv. for
dibromobiaryls or 3 equiv. for bromoiodobiaryls) in hexanes was
added dropwise to a solution of dihalobiaryl (1 equiv.) in toluene
(5 mmol/mL). The reaction mixture was heated at 100 °C. After
1 h, it was cooled to 50 °C and a 1.0 m solution of chlorodiphenyl-
phosphane (2 or 3 equiv. for dibromobiaryls and bromoiodobiaryls,
respectively) in toluene (1 mmol/mL) was quickly added. The solu-
tion was heated for 2.5 hours and then cooled to room temperature.
Water was immediately added followed by extraction into dichloro-
methane. The combined organic layers were dried with sodium sul-
fate and the solvents were removed under reduced pressure.
(6-Chlorobiphenyl-2,2Ј-diyl)bis(diphenylphosphane) (3): Prepared
from 2,2Ј-dibromo-6-chlorobiphenyl. The crude product was puri-
(6-Methoxybiphenyl-2,2Ј-diyl)-bis(diphenylphosphane) (1): Prepared fied by column chromatography on silica gel using cyclohexane as
from 2,2Ј-dibromo-6-methoxybiphenyl. The crude product was the eluent. Crystallization from acetonitrile afforded (6-chlorobi-
Eur. J. Inorg. Chem. 2011, 3387–3397
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3393

L. Bonnafoux, L. Ernst, F. R. Leroux, F. Colobert
FULL PAPER
phenyl-2,2Ј-diyl)bis(diphenylphosphane) (3; 23%) as colourless
crystals. M.p. 158–159 °C. 1H NMR (600 MHz, CDCl3): δ = 7.40–
7.37 (m, 3 H, H5 and o-dpp), 7.34–7.20 (m, 15 H), 7.18–7.09 (m,
5 H), 6.91 (ddd, J = 7.7, 3.0, 1.2 Hz, 1 H, H3), 6.81 (dt, J = 6.9,
1.4 Hz, 2 H, o-dpp), 6.65 ppm (dddd, J = 7.6, 4.3, 1.3, 0.5 Hz, 1
anol afforded 2,2Ј-bisdiphenylphosphanyl-6-phenylbiphenyl (5;
24%) as a colourless powder. M.p. 85–86 °C. 1H NMR (600 MHz,
CDCl3): δ = 7.40–7.24 (m, 12 H), 7.18–7.14 (m, 3 H), 7.12–7.03
(m, 10 H), 7.01 (ddd, J = 7.6, 3.2, 1.4 Hz, 1 H, H3), 6.95 (ddd, J
= 7.6, 3.7, 1.0 Hz, 1 H, H3Ј), 6.89 (ddm, J = 7.6, 4.5 Hz, 1 H, H6Ј),
H, H6Ј). 13C NMR (151 MHz, CDCl3): δ = 145.15 (Cq, dd, J = 6.60–6.56 (m, 2 H, o-dpp), 6.53–6.49 ppm (m, 2 H, o-dpp). 13C
32.5, 6.5 Hz, C1), 144.68 (Cq, dd, J = 32.8, 6.6 Hz, C1Ј), 140.65
(Cq, dd, J = 14.2, 2.3 Hz, C2), 137.89 (Cq, d, J = 14.5 Hz, i-dpp),
137.41 (Cq, dd, J = 12.5, 1.2 Hz, i-dpp), 136.76 (Cq, d, J = 12.5, i-
dpp), 136.75 (Cq, dd, J = 10.1, 1.7 Hz, C2Ј), 136.40 (Cq, dd, J =
NMR (151 MHz, CDCl3): δ = 146.54 (Cq, dd, J = 33.2, 7.8 Hz,
C1Ј), 145.55 (Cq, dd, J = 32.5, 6.3 Hz, C1), 142.00 (Cq, dd, J =
6.0, 2.6 Hz, C6), 141.53 (Cq, t, J = 1.8 Hz, i-ph), 139.02 (Cq, d, J
= 14.6 Hz, i-dpp), 138.47 (Cq, dd, J = 14.1, 0.9 Hz, i-dpp), 138.26
13.1, 1.2 Hz, i-dpp), 134.80 (Cq, dd, J = 7.3, 2.6 Hz, C6), 134.78 (Cq, dd, J = 11.7, 1.9 Hz, C2), 137.38 (Cq, dd, J = 13.6, 0.7 Hz, i-
(CH, d, J = 2.3 Hz, C3Ј), 134.19 (CH, d, J = 20.8 Hz, 2 C, o-dpp),
133.86 (CH, dd, J = 19.0, 3.1 Hz, 2 C, o-dpp), 133.83 (CH, d, J =
20.0 Hz, 2 C, o-dpp), 133.11 (CH, dd, J = 18.9, 1.0 Hz, 2 C, o-
dpp), 132.20 (CH, d, J = 1.3 Hz, C3), 130.71 (CH, dd, J = 6.3,
dpp), 136.58 (Cq, d, J = 13.9 Hz, i-dpp), 135.77 (Cq, dd, J = 11.0,
1.3 Hz, i-dpp), 135.36 (CH, d, J = 2.6 Hz, C3Ј), 134.19 (CH, d, J
= 20.4 Hz, 2 C, o-dpp), 134.18 (CH, dd, J = 19.7, 3.4 Hz, 2 C, o-
dpp), 133.54 (CH, d, J = 1.6 Hz, C3), 132.94 (CH, d, J = 18.7 Hz,
3.3 Hz, C6Ј), 129.68 (CH, C5), 128.85 (CH, C4), 128.34 (CH, d, J 2 C, o-dpp), 132.82 (CH, d, J = 18.6 Hz, 2 C, o-dpp), 132.80 (CH,
= 0.8 Hz, C5Ј), 128.27 (CH, d, J = 6.1 Hz, 2 C, m-dpp), 128.27 dd, J = 4.6, 1.7 Hz, C6Ј), 130.88 (CH, d, J = 0.7 Hz, C5), 130.53
(CH, d, J = 7.5 Hz, 2 C, m-dpp), 128.19 (CH, d, J = 7.3 Hz, 2 C, (d, J = 1.3 Hz, 2 C), 127.37 (2 C, o-, m-ph), 128.50, 128.26, 127.92,
m-dpp), 128.15 (CH, d, J = 6.6 Hz, 2 C, m-dpp), 128.72, 128.29,
128.26, 128.18, 128.05 ppm (CH, 4 p-dpp and C4Ј). 31P NMR
(162 MHz, CDCl3): –12.0 (d), –14.1 ppm (d, J = 22.5 Hz). MS(EI):
127.59, 127.48, 126.07 (CH, 4 p-dpp, p-ph and C4), 128.28 (d, J =
7.1 Hz, 2 C, m-dpp), 128.19 (d, J = 6.6 Hz, 2 C, m-dpp), 127.97 (d,
J = 5.6 Hz, 2 C, m-dpp), 127.91 (d, J = 5.8 Hz, 2 C, m-dpp), 127.65
m/z (%) = 555.3 (Ͻ 1) [M+], 521.1 [M+ – Cl], 479.1 (1) [M+ – Ph], (CH, C4Ј), 127.38 (CH, d, J = 0.9 Hz, C5Ј). 31P NMR (162 MHz,
443.1 (Ͻ 1) [M+ – Cl–Ph], 371.1 (100) [M+ – PPh2], 336 (6) [M+
PPh2–Cl], 257.1 [M+ – PPh2– Cl–Ph], 183 (34) [M+ – PPh2–Cl–2
–
CDCl3): –13.9 (d), –15.1 ppm (d, J = 11.4 Hz). MS(EI): m/z (%) =
598.2 (Ͻ 1) [M+], 413.2 (100) [M+ – PPh2], 183.1 (22) [M+ – PPh2–
Ph]. C36H27ClP2·H3CCN (598.05): calcd. (%) C 76.32, H 5.06; 3 Ph]. C42H32P2 (598.65): calcd. (%) C 84.26, H 5.39; found C
found C 76.44, H 5.06.
83.40, H 5.66.
[2-{5-(Diphenylphosphanyl)benzo[d][1,3]dioxol-4-yl}phenyl]diphen-
2Ј,6-Bis(diphenylphosphanyl)-N,N-dimethylbiphenyl-2-amine (6):
ylphosphane (4): Prepared from 5-bromo-4-(2-bromophenyl)- Prepared from (6,2Ј-dibromobiphenyl-2-yl)dimethylamine. The
benzo[1,3]dioxole. The crude product was purified by column
chromatography on silica gel using cyclohexane as the eluent to
separate phosphafluorene and diphosphane from triphenylphos-
phane. Crystallization from methanol afforded pure [2-{5-(di-
phenylphosphanyl)benzo[d][1,3]dioxol-4-yl}phenyl]diphenyl-
phosphane (4, 18%) as colourless crystals. M.p. 160–161 °C. 1H
crude product was purified by column chromatography on silica
gel using cyclohexane as the eluent to separate phosphafluorene,
diphosphane and triphenylphosphane. Crystallization from aceto-
nitrile afforded pure 2Ј,6-bis(diphenylphosphanyl)-N,N-dimethylbi-
phenyl-2-amine (6, 44%) as colourless needles. M.p. 150–152 °C.
1H NMR (600 MHz, CDCl3): δ = 7.35–7.25 (m, 13 H), 7.22–7.15
NMR (600 MHz, CDCl3): δ = 7.32–7.12 (m, 22 H), 7.11 (dddd, J (m, 7 H), 7.07–7.04 (m, 2 H), 7.02 (dd, J = 8.0, 1.1 Hz, 1 H), 7.00–
= 7.7, 3.6, 1.4, 0.5 Hz, 1 H, H3Ј), 6.89 (ddd, J = 7.5, 4.1, 1.2 Hz,
1 H, H6Ј), 6.72 (d, J = 8.0 Hz, 1 H, H4), 6.57 (dd, J = 8.0, 3.5 Hz,
1 H, H3), 5.71 and 5.12 ppm (both d, J = 1.5, 1 H each, OCH2O).
6.97 (m, 1 H), 6.91–6.88 (m, 2 H), 6.76 (ddd, J = 7.7, 3.2, 1.1 Hz,
1 H), 2.13 ppm (s, 6 H, NMe2). 13C NMR (151 MHz, CDCl3; num-
bering of carbon atoms as for a 2,2Ј-bisphosphane): δ = 152.68
13C NMR (151 MHz, CDCl3; numbering of carbon atoms as for a (Cq, ABX, |ΣJPC| = 10.3 Hz, C6), 146.62 (Cq, ABX, |ΣJPC| =
2,2Ј-bisphosphane): δ = 147.69 (Cq, C5), 146.05 (Cq, dd, J = 11.7,
1.9 Hz, C6), 140.84 (Cq, dd, J = 31.7, 6.7 Hz, C1Ј), 138.46 (Cq, d,
J = 13.3 Hz, i-dpp), 137.70 (Cq, dd, J = 11.0, 1.2 Hz, C2Ј), 137.67
43.4 Hz, C1Ј), 142.38 (Cq, ABX, |ΣJPC| = 38.2 Hz, C1), 139.65 (Cq,
ABX, |ΣJPC| = 14.0 Hz, i-dpp), 138.77 (Cq, d, |ΣJPC| = 13.7 Hz, i-
dpp), 138.63 (Cq, ABX, |ΣJPC| = 13.1 Hz, i-dpp), 138.09 (Cq, d,
(Cq, dd, J = 13.2, 1.4 Hz, i-dpp), 137.52 (Cq, d, J = 13.3 Hz, i- |ΣJPC| = 12.8 Hz, i-dpp), 137.67 (Cq, ABX, |ΣJPC| = 10.9 or 9.5 Hz,
dpp), 136.97 (Cq, dd, J = 13.1, 1.1 Hz, i-dpp), 134.19 (CH, d, J = C2), 136.61 (Cq, ABX, |ΣJPC| = 8.4 Hz, C2Ј), 136.18 (CH, d, |ΣJPC
20.7 Hz, 2 C, o-dpp), 134.01 (CH, d, J = 1.7 Hz, C3Ј), 133.82 (CH, = 2.9 Hz, C3Ј), 133.96 (CH, ABX, |ΣJPC| = 19.9 Hz, 2 C, o-dpp),
|
d, J = 20.1 Hz, 2 C, o-dpp), 133.46 (CH, dd, J = 19.1, 1.6 Hz, 2 C,
o-dpp), 133.30 (CH, dd, J = 18.8, 1.9 Hz, 2 C, o-dpp), 130.69 (CH,
133.25 (CH, ABX, |ΣJPC| = 19.9 Hz, 2 C, o-dpp), 133.19 (CH,
ABX, |ΣJPC| = 21.0 Hz, 2 C, o-dpp), 132.93 (CH, ABX, |ΣJPC| =
dd, J = 5.6, 3.1 Hz, C6Ј), 129.93 (Cq, dd, J = 10.1, 1.4 Hz, C2), 18.8 Hz, 2 C, o-dpp), 132.73 [CH, ABX (“t”), |ΣJPC| = 12.9 Hz,
128.44 (CH, C5Ј), 128.40 (CH, d, J = 1.9 Hz, C3), 128.38–128.29
(CH, overlapped, p-dpp), 128.33 (CH, d, J = 2.4 Hz, C4Ј), 128.31
(CH, p-dpp), 128.28 (CH, d, J = 6.1 Hz, 2 C, m-dpp), 128.18 (CH,
d, J = 6.8 Hz, 2 C, m-dpp), 128.14 (CH, d, J = 6.1 Hz, 2 C, m-
dpp), 128.12 (CH, p-dpp), ≈128.1 (Cq, dd, J ≈ 37, 7 Hz, C1; signal
partially hidden), 128.06 (CH, d, J = 7.0 Hz, 2 C, m-dpp), 127.95
(CH, p-dpp), 108.25 (CH, d, J = 1.0 Hz, C4), 100.85 ppm (CH2,
C6Ј], 128.63 (CH, d, |ΣJPC| = 1.5 Hz, C3), 128.40 (CH, br., C4),
128.33 (CH, p-dpp), 128.31 (CH, |ΣJPC| = 6.4 Hz, 2 C, m-dpp),
128.10 (CH, |ΣJPC| = 5.6 Hz, 2 C, m-dpp), 128.03 (d, |ΣJPC| =
1.6 Hz, C5Ј), 128.02 (CH, |ΣJPC| = 5.4 Hz, 2 C, m-dpp), 127.92
(CH, |ΣJPC| = 5.8 Hz, 2 C, m-dpp), 127.77 (CH, p-dpp), 127.56
(CH, p-dpp), 127.50 (CH, p-dpp), 127.27 (CH, C4Ј), 119.18 (CH,
C5), 43.19 (CH3, NMe2). 31P NMR (162 MHz, CDCl3): –14.0 (s);
OCH2O). 31P NMR (162 MHz, CDCl3): –12.4 (d), –14.2 ppm (d, (CD2Cl2): –14.4 (d), –14.5 ppm (d, J = 5.3 Hz). MS(EI): m/z (%) =
J = 27.6 Hz). MS(EI): m/z (%) = 565.1 (1) [M+], 489.1 (5) [M+
–
564.2 (Ͻ 2) [M+], 521.0 (Ͻ 2) [M+ – NMe2], 488.2 (3) [M+ – Ph],
Ph], 381 (100) [M+ – PPh2], 353 (6) [M+ – PPh2–OCH2], 183.1 380.1 (100) [M+ – PPh2], 364.1 (25) [M+ – Me–PPh2], 336.1 (6)
(25) [M+ – PPh2–2 Ph–OCH2O]. C37H28O2P2·0.5 H3COH (582.17): [M+ – NMe2–PPh2]. C38H33NP2 (565.62): calcd. (%) C 80.69, H
calcd. (%) C 77.31, H 5.19; found C 77.36, H 5.11.
5.88, N 2.46; found C 80.80, H 6.17, N 2.29.
2,2Ј-Bis(diphenylphosphanyl)-6-phenylbiphenyl (5): Prepared from
2,2Ј-dibromo-6-phenylbiphenyl. Purification by chromatography
using cyclohexane as the eluent followed by triturating from meth-
[6-(Trifluoromethoxy)biphenyl-2,2Ј-diyl]bis(diphenylphosphane) (7):
Prepared from 2,2Ј-dibromo-6-trifluoromethoxybiphenyl. Purifica-
tion by chromatography on silica gel using cyclohexane as the elu-
3394
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 3387–3397

Through-Space J(P,P) and J(P,F) Spin–Spin Coupling in Biaryl Diphosphanes
ent followed by triturating from acetonitrile afforded [6-(trifluoro-
crude product was purified by chromatography on silica gel using
methoxy)biphenyl-2,2Ј-diyl]bis(diphenylphosphane) (7, 10%). M.p.
cyclohexane as the eluent. Triturating from methanol afforded pure
179–180. 1H NMR (600 MHz, CDCl3): δ = 7.36–7.26 (m, 13 H), [2-{6-(diphenylphosphanyl)-2,2,3,3-tetrafluoro-2,3-dihydro-
7.26–7.15 (m, 9 H), 7.11 (td, J = 7.5, 1.3 Hz, 1 H, H5Ј), 6.95 benzo[b][1,4]dioxin-5-yl}phenyl]diphenylphosphane (9; 34%) as a
1
(“ddd”, J ≈ 7.7, 2.7, 1.1 Hz, 1 H, H3), 6.90 (m, 2 H, o-dpp),
6.70 ppm (br. dd, J = 7.6, 3.2 Hz, 1 H, H6Ј). 13C NMR (151 MHz,
CDCl3): δ = 147.11 (Cq, qm, JFC = 7.8 Hz, C6), 141.71 (Cq, ABX,
|ΣJPC| = 40.1 Hz, C1Ј), 140.88 (Cq, ABX, |ΣJPC| = 11.5 Hz, C2),
colourless solid. M.p. 169–170 °C. H NMR (600 MHz, CDCl3): δ
= 7.36–7.14 (m, 21 H), 7.05 (d, J = 8.5 Hz, 1 H, H4), 6.97–6.94
(m, 2 H, o-dpp), 6.86 (dd, J = 8.5, 2.6 Hz, 1 H, H3), 6.73 ppm
(ddd, J = 7.6, 4.1, 1.3 Hz, 1 H, H6Ј). 13C NMR (151 MHz, CDCl3;
numbering of carbon atoms as for a 2,2Ј-bisphosphane): δ = 139.99
(Cq, dd, J = 33.3, 6.7 Hz, C1Ј), 137.56 (Cq, br. m, C5), 137.36 (Cq,
139.59 (Cq, ABX, |ΣJPC| = 39.7 Hz, C1), 137.68 (Cq, ABX, |ΣJPC
|
= 14.0 Hz, i-dpp), 137.103 (Cq, ABX, |ΣJPC| = 11.0 Hz, i-dpp),
137.099 (Cq, ABX, |ΣJPC| = 12.4 Hz, i-dpp), 136.88 (Cq, ABX, d, J = 13.5 Hz, i-dpp), 137.17 (Cq, d, J = 12.4 Hz, i-dpp), 137.11
|ΣJPC| = 9.0 Hz, C2Ј), 136.39 (Cq, ABX, |ΣJPC| = 11.7 Hz, i-dpp), (Cq, dd, J = 10.9, 1.4 Hz, C2Ј), 136.84 (Cq, dd, J = 35.0, 6.7 Hz,
134.57 (CH, ABX, |ΣJPC| = 1.8 Hz, C3Ј), 134.16 (CH, ABX, |ΣJPC
= 21.1 Hz, 2 C, o-dpp), 133.71 (CH, ABX, |ΣJPC| = 21.7 Hz, 2 C,
o-dpp), 133.61 (CH, ABX, |ΣJPC| = 20.1 Hz, 2 C, o-dpp), 133.18
|
C1), 136.50 (Cq, dd, J = 12.0, 1.2 Hz, i-dpp), 136.10 (Cq, dd, J =
12.8, 1.2 Hz, i-dpp), 135.95 (Cq, dd, J = 13.5, 1.9 Hz, C2), 135.33
(Cq, v.br. d, J ≈ 10.2 Hz, C6), 134.90 (CH, d, J = 2.4 Hz, C3Ј),
134.03 (CH, dd, J = 20.8, 0.5 Hz, 2 C, o-dpp), 133.58 (CH, br. d,
J = 19.8 Hz, 2 C, o-dpp), 133.54 (CH, dd, J = 18.8, 2.7 Hz, 2 C,
o-dpp), 133.09 (CH, dd, J = 18.8, 1.4 Hz, 2 C, o-dpp), 130.94 (CH,
dd, J = 6.2, 3.2 Hz, C6Ј), 130.52 (CH, d, J = 1.5 Hz, C3), 128.88
(CH, d, J = 0.5 Hz, p-dpp), 128.78 (CH, C4Ј), 128.56 (CH, d, J =
(CH, ABX, |ΣJPC| = 20.1 Hz, 2 C, o-dpp), 131.84 (CH, ABX, |ΣJPC
|
= 1.3 Hz, C3), 131.22 (CH, ABX, |ΣJPC| = 5.5 or 4.1 Hz, C6Ј),
128.88 (CH, C4), 128.77–128.13 (CH, several m + s, 13 C, 4 m-
dpp, 4 p-dpp, C4Ј), 128.11 (CH, C5Ј), 120.11 (Cq, q, JFC
=
258.0 Hz, CF3), 119.63 (CH, q, J = 1.7 Hz, C5). 31P NMR
(162 MHz, CDCl3): δ = –13.7 ppm (s); (CD2Cl2): δ = –13.90 (d), 0.9 Hz, C5Ј), 128.42 (CH, d, J = 7.2 Hz, 2 C, m-dpp), 128.41 (CH,
–14.15 ppm [dq, J(P,P) = 22.3, J(P,F) = 1.4 Hz]. 19F NMR
p-dpp), 128.38 (CH, d, J = 6.1 Hz, 2 C, m-dpp), 128.31 (CH, d, J
(376 MHz, CD2Cl2): δ = –56.9 ppm [d, J(P,F) = 1.4 Hz]. MS(EI): = 6.2 Hz, 2 C, m-dpp), 128.30 (CH, p-dpp), 128.27 (CH, p-dpp),
m/z (%) = 606.1 (Ͻ 2) [M+], 529.2 (6) [M+ – Ph], 421.1 (100) [M+
–
128.26 (CH, d, J = 6.2 Hz, 2 C, m-dpp), 116.95 ppm (CH, br., C4),
111.99 (Cq, tt, J = 267.0, 40.2 Hz, CF2CF2). 19F NMR (376 MHz,
CDCl3): –90.4 (ddd, J = 148.4, 18.4, 10.1 Hz), –91.3 (dddd, J =
147.3, 18.9, 10.1, 2.5 Hz), –92.2 (dddd, J = 148.4, 18.9, 5.1, 3.8 Hz),
–93.7 ppm (ddd, J = 147.3, 18.4, 3.8 Hz). 31P NMR (162 MHz,
CDCl3): –13.9 (ddd, J = 24.6, 5.1, 2.5 Hz), –14.7 ppm (d, J =
24.6 Hz). MS(EI): m/z (%) = 652.6 (Ͻ 1) [M+], 575.1 (2) [M+ – Ph],
467.1 (100) [M+ – PPh2], 183.1 [M+ – 2 PPh2–C2F4]. C38H26F4O2P2
(652.55): calcd. (%) C 69.94, H 4.02; found C 69.56, H 4.37.
PPh2], 353.2 (3) [M+ – PPh2–3 F], 336.2 (8) [M+ – PPh2–OCF3],
260.3 (11) [M+ – PPh2–OCF3–Ph], 183.1 (51) [M+ – PPh2–OCF3–
2 Ph]. C37H27F3OP2 (606.55): calcd. (%) C 73.27, H 4.49; found C
72.91, H 4.63.
[2-{5-(Diphenylphosphanyl)-2,2-difluorobenzo[d][1,3]dioxol-4-yl]-
phenyl]diphenylphosphane (8): Prepared from 5-bromo-2,2-difluoro-
4-(2-iodophenyl)benzo[1,3]dioxole. The crude product was purified
by chromatography on silica gel using cyclohexane as the eluent.
Triturating from methanol afforded pure [2-{5-(diphenylphos-
phanyl)-2,2-difluorobenzo[d][1,3]dioxol-4-yl}phenyl]diphenylphos-
Dicyclohexyl[2-{5-(dicyclohexylphosphanyl)-2,2-difluorobenzo[d]-
[1,3]dioxol-4-yl}phenyl]phosphane (10): At 25 °C, butyllithium
(27.3 mmol, 3 equiv.) in hexanes (17.5 mL) was added dropwise to
a solution of 5-bromo-2,2-difluoro-4-(2-iodophenyl)benzo[d][1,3]-
dioxole (4.00 g, 9.11 mmol, 1 equiv.) in toluene (46.0 mL). After
1 h, a solution of chlorodicyclohexylphosphane (6.36 g, 6.00 mL,
27.3 mmol, 3 equiv.) in toluene (30.0 mL) was added. After 2 h,
water (70.0 mL) was added followed by extraction into dichloro-
methane (3ϫ 70.0 mL). The combined organic layers were dried
with sodium sulfate, filtered and the solvents evaporated. The crude
product was purified by chromatography on silica gel. Triturating
from ethyl acetate afforded pure dicyclohexyl[2-{5-(dicyclohex-
ylphosphanyl)-2,2-difluorobenzo[d][1,3]dioxol-4-yl}phenyl]phos-
phane (10; 3.00 g, 5.25 mmol, 53%) as a colourless solid. M.p. 194–
195 °C. 1H NMR (600 MHz, CDCl3): δ = 7.56 (m, 1 H, H3Ј), 7.42–
7.36 (m, 2 H, H4Ј, H5Ј), 7.24 (dd, J = 8.3, 1.5 Hz, 1 H, H3), 7.14
(m, 1 H, H6Ј), 7.06 (d, J = 8.2 Hz, 1 H, H4), 2.00–1.92 (m, 2 H),
1.85–1.48 (m, 20 H), 1.34–0.88 ppm (m, 22 H). 13C NMR
(151 MHz, CDCl3; numbering of carbon atoms as for a 2,2Ј-bis-
phosphane): δ = 143.09 (Cq, br., C5), 142.26 (Cq, br. d, J = 11.5 Hz,
C6), 141.30 (Cq, dd, J = 31.0, 5.2 Hz, C1Ј), 135.98 (Cq, dd, J =
20.0, 1.4 Hz, C2Ј), 132.88 (CH, d, J = 3.1 Hz, C3Ј), 132.26 (Cq, dd,
J = 35.2, 5.6 Hz, C1), 131.90 (CH, dd, J = 6.1, 1.9 Hz, C6Ј), 131.44
(Cq, dd, J = 22.6, 1.9 Hz, C2), 131.30 (Cq, dd, J = 255.2, 253.9 Hz,
CF2), 127.89 (CH, d, J = 3.0 Hz, C3), 127.69 (CH, br., C5Ј), 127.45
(CH, C4Ј), 107.69 (CH, br., C4); C1 of cyclohexyl: 36.68 (CH, dd,
J = 16.8, 1.3 Hz), 35.43 (CH, dd, J = 15.4, 1.2 Hz), 33.87 (CH, d,
J = 14.5), 33.66 (CH, d, J = 14.0 Hz); C2,6 and C3,5 of cyclohexyl:
30.88 (CH2, dd, J = 11.7, 5.8 Hz), 30.78 (CH2, d, J = 14.2 Hz),
30.66 (CH2, dd, J = 11.6, 5.7 Hz), 30.32 (CH2, d, J = 19.7 Hz),
30.19 (CH2, d, J = 14.5 Hz), 30.14 (CH2, d, J = 17.8 Hz), 29.10
1
phane (8; 47%) as a colourless solid. M.p. 153–154 °C. H NMR
(600 MHz, CDCl3): δ = 7.35–7.14 (m, 21 H), 7.00–6.97 (m, 2 H, o-
dpp), 6.95 (d, J = 8.2 Hz, 1 H, H4), 6.85 (ddd, J = 7.6, 4.1, 1.3 Hz,
1 H, H6Ј), 6.78 ppm (dd, J = 8.2, 3.1 Hz, 1 H, H3). 13C NMR
(151 MHz, CDCl3; numbering of carbon atoms as for a 2,2Ј-
bisphosphane): δ = 143.70 (Cq, C5), 142.33 (Cq, dd, J = 11.6,
1.7 Hz, C6), 139.13 (Cq, dd, J = 32.2, 6.5 Hz, C1Ј), 137.69 (Cq, d,
J = 13.6 Hz, i-dpp), 137.43 (Cq, d, J = 11.8, 1.1 Hz, C2Ј), 136.83
(Cq, d, J = 12.5 Hz, i-dpp), 136.69 (Cq, dd, J = 13.0, 1.6 Hz, i-
dpp), 136.56 (Cq, dd, J = 12.2, 1.3 Hz, i-dpp), 134.43 (CH, d, J =
2.0 Hz, C3Ј), 133.87 (CH, d, J = 20.6 Hz, 2 C, o-dpp), 133.68 (CH,
d, J = 20.4 Hz, 2 C, o-dpp), 133.61 (CH, dd, J = 19.1, 2.2 Hz, 2 C,
o-dpp), 133.52 (Cq, dd, J = 14.0, 1.6 Hz, C2), 133.15 (CH, dd, J =
18.8, 1.6 Hz, 2 C, o-dpp), 131.24 (Cq, dd, J = 257.1, 255.2 Hz, CF2),
130.72 (CH, dd, J = 5.7, 3.1 Hz, C6Ј), 129.79 (CH, d, J = 1.7 Hz,
C3), 129.31 (Cq, dd, J = 36.9, 6.9 Hz, C1), 128.95 (CH, C4Ј), 128.72
(CH, p-dpp), 128.58 (CH, C5Ј), 128.57 (CH, p-dpp), 128.38 (CH,
d, J = 7.0 Hz, 2 C, m-dpp), 128.34 (CH, d, J = 6.1 Hz, 2 C, m-
dpp), 128.31 (CH, d, J = 6.9 Hz, 2 C, m-dpp), 128.32 (CH, p-
dpp), 128.30 (CH, d, J = 6.2 Hz, 2 C, m-dpp), 128.23 (CH, p-dpp),
108.97 ppm (CH, C4). 19F NMR (376 MHz, CDCl3): –49.57 (d, J =
95.4 Hz), –49.96 ppm (dd, J = 95.4, 2.3 Hz). 31P NMR (162 MHz,
CDCl3): –12.72 (dd, J = 28.7, 2.3 Hz), –14.15 ppm (d, J = 28.7 Hz).
MS(EI): m/z (%) = 602.1 (Ͻ 1) [M+], 525.2 (8) [M+ – Ph], 417.1
(100) [M+ – PPh2], 183.1 (51) [M+ – 2 PPh2–CF2]. HRMS for
C37H26F2O2P2 [M + H]: calcd. 603.1449; found 603.1378.
[2-{6-(Diphenylphosphanyl)-2,2,3,3-tetrafluoro-2,3-dihydrobenzo[b]-
[1,4]dioxin-5-yl}phenyl]diphenylphosphane (9): Prepared from 5-
bromo-2,2-difluoro-4-(2-iodophenyl)benzo[b][1,3]dioxole. The
Eur. J. Inorg. Chem. 2011, 3387–3397
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3395

L. Bonnafoux, L. Ernst, F. R. Leroux, F. Colobert
FULL PAPER
(CH2, d, J = 7.7 Hz), 28.94 (CH2, d, J = 5.9 Hz), 27.58 (CH2, d, J
= 11.3 Hz), 27.56 (CH2, d, J = 6.4 Hz), 27.49 (CH2, d, J = 7.7 Hz),
27.48 (CH2, d, J = 11.1 Hz), 27.31 (CH2, d, J = 9.3 Hz), 27.25
(CH2, d, J = 9.0 Hz), 27.19 (CH2, d, J = 11.1 Hz), 27.14 (CH2, d,
J = 11.8 Hz); C4 of cyclohexyl: 26.71 ppm (CH2, m, 2 C), 26.34
(CH2, br., 2 C). 19F NMR (376 MHz, CDCl3): –49.20 (d, J =
98.4 Hz), –49.89 ppm (d, J = 98.4 Hz). 31P NMR (162 MHz,
CDCl3): –11.0 (d), –12.9 ppm (d, J = 22.7 Hz). MS(EI): m/z (%) =
ene (3.00 mL) was added slowly. After 15 minutes, the reaction mix-
ture was allowed to reach 25 °C and was treated with a saturated
aqueous solution of ammonium chloride (15.0 mL). The mixture
was extracted into ethyl acetate (3ϫ 15.0 mL), and the combined
organic layers were dried with sodium sulfate. Evaporation of the
solvent followed by column chromatography on silica gel using cy-
clohexane as the eluent gave 2,2-difluoro-6-phenyl-6H-benzo[2,3]-
phosphindolo[4,5-d][1,3]dioxole (12; 0.15 g, 0.45 mmol, 30%) as a
626.3 (Ͻ 1) [M+], 543.3 (100) [M+ – Cy], 461.2 (17) [M+ – 2 Cy], yellow oil. 1H NMR (600 MHz, CDCl3): δ = 8.10 (dq, J = 7.8,
295.1 (14) [M+ – 4 Cy], 263 (63) [M+ – PCy2–2 Cy]. C37H50F2O2P2
(626.74): calcd. (%) C 70.91, H 8.04; found C 71.12, H 8.11.
0.8 Hz, 1 H, H10), 7.69 (ddt, J = 7.5, 5.1, 0.9 Hz, 1 H, H7), 7.51
(td, J = 7.6, 1.2 Hz, 1 H, H9), 7.38 (tdd, J = 7.5, 2.8, 1.2 Hz, 1 H,
H8), 7.37 (dd, J = 8.0, 5.2 Hz, 1 H, H5), 7.31–7.22 (m, 5 H, Ph),
7.02 ppm (dd, J = 8.0, 2.2 Hz, 1 H, H4). 13C NMR (151 MHz,
CDCl3): δ = 144.65 (Cq, t, J = 1.1 Hz, C3a), 143.18 (Cq, d, J =
4.6 Hz, C6a), 139.55 (Cq, d, J = 1.1 Hz, C10a), 138.82 (Cq, q, J =
1.3 Hz, C10c), 138.34 (Cq, d, J = 5.1 Hz, C5a), 135.63 (Cq, d, J =
19.5 Hz, i-ph), 132.63 (CH, d, J = 20.6 Hz, 2 C, o-ph), 131.93 (Cq,
t, J = 255.9 Hz, C2), 130.33 (CH, d, J = 21.9 Hz, C7), 129.64 (CH,
d, J = 1.2 Hz, p-ph), 129.13 (CH, C9), 128.80 (CH, d, J = 7.8 Hz,
2 C, m-ph), 128.33 (CH, d, J = 7.8 Hz, C8), 126.90 (Cq, d, J =
4.2 Hz, C10b), 125.45 (CH, d, J = 24.0 Hz, C5), 125.02 (CH, C10),
108.44 ppm (CH, d, J = 8.5 Hz, C4). 19F NMR (CDCl3, 376 MHz):
δ = –49.59 (d), –49.82 ppm (d, J = 96.4 Hz). 31P NMR (CDCl3,
162 MHz): δ = –5.2 ppm. MS(EI): m/z (%) = 340.1 (100) [M+],
Dicyclohexyl[2-{6-(dicyclohexylphosphanyl)-2,2,3,3-tetrafluoro-
2,3-dihydrobenzo[b][1,4]dioxin-5-yl}phenyl]phosphane (11): At 25 °C,
butyllithium (12.3 mmol, 3 equiv.) in hexanes (7.87 mL) was added
dropwise to a solution of 6-bromo-2,2,3,3-tetrafluoro-5-(2-iodo-
phenyl)-2,3-dihydrobenzo[b][1,4]dioxine (2.00 g, 4.09 mmol,
1 equiv.) in toluene (20 mL). After 1 h, a solution of chlorodicy-
clohexylphosphane (2.86 g, 2.71 mL, 12.27 mmol, 3 equiv.) in tolu-
ene (13.0 mL) was added. After 2 h, water (30.0 mL) was added
followed by extraction into dichloromethane (3ϫ 30.0 mL). The
combined organic layers were dried with sodium sulfate, filtered
and the solvents evaporated. The crude product was purified by
chromatography on silica gel. Triturating from methanol afforded
dicyclohexyl[2-{6-(dicyclohexylphosphanyl)-2,2,3,3-tetrafluoro-
2,3-dihydrobenzo[b][1,4]dioxin-5-yl}phenyl]phosphane (11; 2.00 g,
2.96 mmol, 73%) as colourless crystals. M.p. 97–99 °C. 1H NMR
(600 MHz, CDCl3): δ = 7.56 (m, 1 H, H3Ј), 7.40 (td, J = 7.4,
1.5 Hz, 1 H, H4Ј), 7.36 (br. t, J = 7.4 Hz, 1 H, H5Ј), 7.30 (dd, J =
8.5, 1.0 Hz, 1 H, H3), 7.14 (d, J = 8.5 Hz, 1 H, H4), 7.05 (ddd, J
= 7.5, 3.6, 1.5 Hz, 1 H, H6Ј), 2.02–1.43 (m, 24 H), 1.34–0.87 ppm
(m, 20 H). 13C NMR (151 MHz, CDCl3; numbering of carbon
atoms as for a 2,2Ј-bisphosphane): δ = 141.54 (Cq, dd, J = 31.1,
5.4 Hz, C1Ј), 139.48 (Cq, dd, J = 33.8, 5.1 Hz, C1), 137.21 (Cq, d,
J = 2.7 Hz, C5), 136.29 (Cq, dd, J = 19.5, 1.9 Hz, C2Ј), 135.16 (Cq,
dt, J = 10.2, 1.9 Hz, C6), 134.12 (Cq, dd, J = 22.4, 2.2 Hz, C2),
132.72 (CH, d, J = 3.0 Hz, C3Ј), 132.25 (CH, dd, J = 6.3, 2.0 Hz,
C6Ј), 128.94 (CH, d, J = 2.8 Hz, C3), 127.46 (CH, br., C5Ј), 127.27
(CH, C4Ј), 115.53 (CH, C4), CF2 signals not observed; C1 of cyclo-
hexyl: 36.72 (CH, dd, J = 17.4, 1.3 Hz), 35.54 (CH, dd, J = 15.3,
1.2 Hz), 33.47 (CH, d, J = 14.9), 33.44 (CH, d, J = 14.3 Hz); C2,6
and C3,5 of cyclohexyl: 31.16 (CH2, dd, J = 12.4, 6.5 Hz), 30.60
(CH2, dd, J = 11.4, 5.9 Hz), 30.54 (CH2, d, J = 13.0 Hz), 30.31
(CH2, d, J = 20.1 Hz), 30.13 (CH2, d, J = 17.3 Hz), 29.77 (CH2,
br. d, J = 10.3 Hz), 29.73 (CH2, d, J = 12.9 Hz), 29.31 (CH2, d, J
= 7.2 Hz), 27.64 (CH2, d, J = 6.9 Hz), 27.59 (CH2, d, J = 10.8 Hz),
27.50 (CH2, d, J = 10.4 Hz), 27.48 (CH2, d, J = 8.7 Hz), 27.34
(CH2, d, J = 9.8 Hz), 27.21 (CH2, d, J = 10.5 Hz, 2 C), 27.10 (CH2,
d, J = 11.8 Hz); C4 of cyclohexyl: 26.73 (CH2, d, J = 1.1 Hz), 26.68
(CH2, d, J = 1.1 Hz), 26.38 (CH2, d, J = 0.8 Hz), 26.29 ppm (CH2,
d, J = 0.9 Hz). 19F NMR (376 MHz, CDCl3): signals 3–4 Hz wide,
–88.39 (dt, J ≈ 149, 18 Hz), –89.50 (dt, J ≈ 148, 18 Hz), –93.94 (dd,
J ≈ 149, 19 Hz), –95.02 ppm (ddd, J ≈ 148, 19, 2 Hz). 31P NMR
(162 MHz, CDCl3): –10.7 (d), –12.9 ppm (d, J = 22.2 Hz). MS(EI):
m/z (%) = 676.74 (Ͻ 1) [M+], 593.3 (100) [M+ – Cy], 511.2 (16)
[M+ – 2 Cy], 427.1 (10) [M+ – 3 Cy], 313.1 (69) [M+ – P – 4 Cy].
C38H50F4O2P2 (676.74): calcd. (%) C 67.44, H 7.45; found C 67.61,
H 7.53.
308.2 (15) [M+ – F–O], 273.2 (21) [M+ – OCF2], 263.1 (34). [M+
–
Ph], 234.2 (47) [M+ – PPh], 169.1 (64) [M+ – PPh–OCF2], 139.2
(80) [M+ – PPh–Ph–F].
2,2,3,3-Tetrafluoro-7-phenyl-3,7-dihydro-2H-benzo[2,3]phosphind-
olo[4,5-b][1,4]dioxine (13): At –78 °C, butyllithium (4.50 mmol,
3 equiv.) in hexane (2.9 mL) was added slowly to a solution of 6-
bromo-2,2,3,3-tetrafluoro-5-(2-iodophenyl)-2,3-dihydrobenzo[b]-
[1,4]dioxine (0.74 g, 1.50 mmol, 1 equiv.) in tetrahydrofuran
(3.00 mL). After 60 minutes, a solution of dichlorophenylphos-
phane (0.54 g, 0.41 mL, 3.00 mmol, 2 equiv.) in toluene (3.00 mL)
was added slowly. After 15 minutes, the reaction mixture was al-
lowed to reach 25 °C and was treated with a saturated aqueous
solution of ammonium chloride (15.0 mL). The mixture was ex-
tracted into ethyl acetate (3ϫ 15.0 mL), and the combined organic
layers were dried with sodium sulfate. Evaporation of the solvent
followed by column chromatography on silica gel using cyclohex-
ane as the eluent gave 2,2,3,3-tetrafluoro-7-phenyl-3,7-dihydro-2H-
benzo[2,3]phosphindolo[4,5-b][1,4]dioxine (13, 0.27 g, 0.68 mmol,
45%) as an orange solid. M.p. 84–85 °C. 1H NMR (600 MHz,
CDCl3): δ = 8.41 (dq, J = 8.0, 0.8 Hz, 1 H, H11), 7.71 (dddd, J =
7.5, 5.6, 1.2, 0.7 Hz, 1 H, H8), 7.54 (ddd, J = 8.0, 7.4, 1.2 Hz, 1 H,
H10), 7.45 (dd, J = 8.2, 4.9 Hz, 1 H, H6), 7.41 (tdd, J = 7.4, 2.8,
1.1 Hz, 1 H, H9), 7.33–7.24 (m, 5 H, o-, m-, p-ph), 7.10 (dd, J =
8.2, 2.3 Hz, 1 H, H5). 13C NMR (151 MHz, CDCl3): δ = 143.4 (Cq,
d, J = 2.6 Hz, C7a), 140.8 (Cq, d, J = 4.1 Hz, C6a), 140.7 (Cq, d,
J = 1.3 Hz, C11a), 138.0 (Cq, br., C4a), 134.9 (Cq, d, J = 19.1 Hz,
i-ph), 134.4 (Cq, br. d, J = 1.2 Hz, C11c), 132.9 (CH, d, J =
20.6 Hz, 2 C, o-ph), 132.4 (Cq, d, J = 4.4 Hz, C11b), 130.4 (CH,
d, J = 22.2 Hz, C8), 129.8 (CH, d, J = 0.9 Hz, p-ph), 129.2 (CH,
s, C10), 128.9 (CH, d, J = 7.9 Hz, 2 C, m-ph), 128.3 (CH, d, J =
8.1 Hz, C9), 126.7 (CH, d, J = 23.3 Hz, C6), 126.3 (CH, s, C11),
116.6 (CH, d, J = 8.5 Hz, C5), 112.3 (Cq, ca. tt, J ≈ 268, 40 Hz,
C2 or C3), 112.1 ppm (Cq, ca. tt, J ≈ 266, 40 Hz, C3 or C2). 19F
NMR (CDCl3, 376 MHz): δ = –91.0 ppm –92.3 ppm (m, 4 F). 31P
NMR (CDCl3, 161 MHz): δ = –7.8 (s). MS(EI): m/z (%) = 390.1
(100) [M+], 359.2 (29) [M+ – O–F], 313.1 (67) [M+ – Ph], 295.2 (14)
2,2-Difluoro-6-phenyl-6H-benzo[2,3]phosphindolo[4,5-d][1,3]dioxole
(12): At –78 °C, butyllithium (4.50 mmol, 3 equiv.) in hexane
(2.9 mL) was added slowly to a solution of 5-bromo-2,2-difluoro-
4-(2-iodophenyl)benzo[1,3]dioxole (0.66 g, 1.50 mmol, 1 equiv.) in
tetrahydrofuran (3.00 mL). After 60 minutes, a solution of dichlo-
rophenylphosphane (0.54 g, 0.41 mL, 3.00 mmol, 2 equiv.) in tolu-
[M+ – Ph–F], 202.2 (12) [M+ – PPh–CF2–O–F], 169.1 (24) [M+
–
PPh–Ph–2 F], 157.1 (44) [M+ – PPh–Ph–CF2]. C20H11F4O2P·H2O
(408.28): calcd. (%) C 58.84, H 3.21; found C 58.31, H 3.33.
3396
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Eur. J. Inorg. Chem. 2011, 3387–3397

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Acknowledgments
We are grateful to the Ministère de la Recherche (France) and the
Centre National de la Recherche Scientifique (CNRS) (France).
L. B. thanks LONZA AG (Switzerland) for a PhD grant. We thank
Petra Holba-Schulz for carefully recording countless NMR spectra,
1
Dr. Kerstin Ibrom for help with the selective H{31P} experiments
and Dr. Lydia Brelot (Service de Radiocristallographie, University
of Strasbourg, France) for assistance with single crystal structure
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Received: April 20, 2011
Published Online: June 28, 2011
Eur. J. Inorg. Chem. 2011, 3387–3397
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3397