Intramolecular dehydrofluorinative coupling of η5-pentamethylcyclopentadienyl and pentafluorophenylphosphine ligands in rhodium complexes

Article abstract of DOI:10.1021/om020612n

The rhodium(III) complex [Cp*RhCl(dfppe)]BF₄,1, undergoes rapid stepwise intramolecular dehydrofluorinative carbon-carbon coupling on addition of proton sponge to produce [{η⁵,κP,κP-C₅Me₃[CH₂ C₆F₄-2-P(C₆F₅)CH₂]₂ -1,3}RhCl]BF₄. The reaction requires less than the stoichiometric quantity of proton sponge and also occurs on addition of Bu₄ⁿNF or in the presence of polymer-supported fluoride. NMR studies of reactions between a series of complexes and proton sponge have revealed the necessary conditions for intramolecular dehydrofluorinative coupling in pentamethylcyclopentadienyl rhodium(III) phosphine complexes. The complex must be cationic, and the phosphine, which can be either part of a chelating ligand or monodentate need have only one pentafluorophenyl substituent. The reaction is rapid where Cp* and C₆F₅ are held in close proximity. The compounds [Cp*RhCl-{(C₆F₅)₂PC₆H₄ SMe-2}]BF₄, 7, and the diastereoisomer of [Cp*RhCl{(C₆F₅)PhPC₆H₄SMe-2}]- BF₄, 11a, in which Cp* and C₆F₅ are cis, undergo rapid coupling on treatment with proton sponge. The diastereoisomer of [Cp*RhCl{(C₆F₅)PhPC₆H₄SMe-2}]B F₄, in which Cp* and C₆F₅ are trans, undergoes isomerization to 11a at a much slower rate than that of coupling. Cationic complexes of monodentate phosphines, in which there is rotation about the Rh-P bond, undergo coupling on addition of proton sponge, but at a much slower rate than for 1, 7, and 11a. The structures of [{η⁶,κP,κP-C₅Me₄CH₂C ₆F₄-2-P(C₆F₅)CH₂CH₂ P(C₆F₅)₂}RhCl]-BF₄, [{η⁵,κP,κS-C₅Me₄CH₂C ₆F₄P(C₆F₅)C₆H₄ SMe}RhCl]BF₄, and [Cp*RhCl₂{PEt₂(C₆F₅)}] have been determined by single-crystal X-ray diffraction.

Full text of DOI:10.1021/om020612n

5726
Organometallics 2002, 21, 5726-5737
In tr a m olecu la r Deh yd r oflu or in a tive Cou p lin g of
η5-P en ta m eth ylcyclop en ta d ien yl a n d
P en ta flu or op h en ylp h osp h in e Liga n d s in Rh od iu m
Com p lexes
Ronan M. Bellabarba, Mark Nieuwenhuyzen, and Graham C. Saunders*
School of Chemistry, Queen’s University Belfast, David Keir Building, Belfast, BT9 5AG, U.K.
Received J uly 29, 2002
The rhodium(III) complex [Cp*RhCl(dfppe)]BF4, 1, undergoes rapid stepwise intramolecular
dehydrofluorinative carbon-carbon coupling on addition of proton sponge to produce
[{η5,κP,κP-C5Me3[CH2C6F4-2-P(C6F5)CH2]2-1,3}RhCl]BF4. The reaction requires less than the
stoichiometric quantity of proton sponge and also occurs on addition of Bun NF or in the
4
presence of polymer-supported fluoride. NMR studies of reactions between a series of
complexes and proton sponge have revealed the necessary conditions for intramolecular
dehydrofluorinative coupling in pentamethylcyclopentadienyl rhodium(III) phosphine com-
plexes. The complex must be cationic, and the phosphine, which can be either part of a
chelating ligand or monodentate need have only one pentafluorophenyl substituent. The
reaction is rapid where Cp* and C6F5 are held in close proximity. The compounds [Cp*RhCl-
{(C6F5)2PC6H4SMe-2}]BF4, 7, and the diastereoisomer of [Cp*RhCl{(C6F5)PhPC6H4SMe-2}]-
BF4, 11a , in which Cp* and C6F5 are cis, undergo rapid coupling on treatment with proton
sponge. The diastereoisomer of [Cp*RhCl{(C6F5)PhPC6H4SMe-2}]BF4, in which Cp* and C6F5
are trans, undergoes isomerization to 11a at a much slower rate than that of coupling.
Cationic complexes of monodentate phosphines, in which there is rotation about the Rh-P
bond, undergo coupling on addition of proton sponge, but at a much slower rate than for 1,
7, and 11a . The structures of [{η5,κP,κP-C5Me4CH2C6F4-2-P(C6F5)CH2CH2P(C6F5)2}RhCl]-
BF4, [{η5,κP,κS-C5Me4CH2C6F4P(C6F5)C6H4SMe}RhCl]BF4, and [Cp*RhCl2{PEt2(C6F5)}] have
been determined by single-crystal X-ray diffraction.
In tr od u ction
(NCMe)2]PF6 in its ligand substitution reactions with
phosphines and phosphites is in contrast to the low
diastereoselectivity shown by [{η5-C5H2(CO2Et)MeR-
2,4}Ru(NCMe)2{P(OMe)3}]PF6.4 Despite the advantages
offered by these ligands, the number of reports of
complexes of chelating hybrid cyclopentadienyl-phos-
phine ligands is somewhat limited.1 One reason for this
scarcity is the lack of convenient syntheses. Three
synthetic approaches to complexes of these hybrid
ligands can be envisaged: (i) prior synthesis of the
hybrid ligand followed by coordination to the metal; (ii)
coordination of both functionalities of the hybrid ligand
to the metal followed by intramolecular coupling; (iii)
coordination of one functionality of the hybrid ligand
to the metal followed by intermolecular coupling to the
second functionality and subsequent chelation. The first
strategy is the most commonly adopted route, but
suffers from the disadvantage that ligand syntheses are
often elaborate, involving multiple steps, and conse-
quently poor overall yields are obtained.1 The second
approach provides a method of overcoming this problem.
Since the two functionalities are held in close proximity
by coordination to the metal, high yields coupled with
high regioselectivities are expected. Despite the appeal
Cyclopentadienyl and phosphine ligands are two of
the most common and important classes of ligand
employed in organometallic chemistry. The coupling of
these two ligand types in chelating bi- or trifunctional
ligands is of current interest, since the resulting hybrid
cyclopentadienyl-phosphine ligands are expected to af-
fect metal reactivity differently from the separated
ligands and endow the complexes with enhanced regio-
and stereoselectivities in their reactions.1 For a number
of cases these expectations have been realized. For
example, zirconium complexes of trifunctional cyclopen-
tadienyl-diphosphines have been isolated, the unlinked
cyclopentadienide phosphine analogues of which are
either unknown or unstable;2 [{η5,κP-indenyl-CH2CH2-
PPh2}RhMe(CO)]BF4 reacts with 1-phenylpropyne at
room temperature, affording [{η5,κP-indenyl-CH2CH2-
PPh2}RhMe{C(Ph)dC(Me)C(Me)dO}]BF4, whereas un-
der the same conditions [(η5-indenyl)RhMe(CO)(PPh3)]-
BF4 does not react;3 and the high diastereoselectivity
shown by [{η5,κP-C5H2(CO2CH2CH2PPh2)MeR-2,4}Ru-
* To whom correspondence should be addressed. E-mail:
g.saunders@qub.ac.uk.
(1) Butenscho¨n, H. Chem. Rev. 2000, 100, 1527.
(2) (a) Fryzuk, M. D.; Mao, S. H. S.; Zaworotko, M. J .; MacGillivray,
L. R. J . Am. Chem. Soc. 1993, 115, 5336. (b) Bosch, B. E.; Erker, G.;
Fro¨hlich, R.; Meyer, O. Organometallics 1997, 16, 5449. (c) Wang, T.-
F.; Lai, C.-Y. J . Organomet. Chem. 1997, 546, 179
(3) Kataoka, Y.; Iwato, Y.; Shibahara, A.; Yamagata, T.; Tani, K. J .
Chem. Soc., Chem. Commun. 2000, 841.
(4) Onitsuka, K.; Dodo, N.; Matsushima, Y.; Takahashi, S. J . Chem.
Soc., Chem. Commun. 2001, 521.
10.1021/om020612n CCC: $22.00 © 2002 American Chemical Society
Publication on Web 11/21/2002

Intramolecular Dehydrofluorinative Coupling
Organometallics, Vol. 21, No. 26, 2002 5727
of this approach, there are very few reports of intramo-
lecular reactions leading to complexes of hybrid cyclo-
pentadienyl-phosphine ligands. The reaction of deca-
fluorodiazabenzene with [CpRuMe(PPh3)2] produces the
hybrid cyclopentadienyl-phosphine ligand complex [(η5,κP-
C5H4C6H4PPh2)Ru(κC1,κN2-C6F4NdNC6F5] in moderate
yield,5 Nelson and co-workers have reported that the
rhodium complex cation [Cp*RhCl(PPh2CHdCH2)2]+
undergoes radical or base-promoted hydroalkylation to
give a mixture of the 1,2 and 1,3 isomers of [{η5,κP,κP-
C5Me3(CH2CH2CH2PPh2)2}RhCl]+ in 35% and 42% yield,
respectively,6,7 and we have reported that in refluxing
ethanol the salts [(η5-C5Me4R)MX(dfppe)]BF4 (M ) Rh,
X ) Cl or Br, R ) H, Me or Et; M ) Ir, X ) Cl, R ) Me;
dfppe ) (C6F5)2PCH2CH2P(C6F5)2) undergo dehydroflu-
orinative C-C coupling to give [{η5,κP,κP-C5Me2R-
[CH2C6F4-2-P(C6F5)CH2]2}MX]BF4 in virtually quanti-
tative yield.8-13 Although not definitely established, it
is probable that the reaction between [Cp*RhCl(µ-Cl)]2
Here we describe dehydrofluorinative carbon-carbon
coupling as a convenient synthetic route to rhodium
complexes of bi- and trifunctional hybrid cyclopentadi-
enide-phosphine ligands, suggest a possible mechanism
for the reaction, and report the necessary conditions for
such coupling to occur. Part of this work has been
communicated.12,17
Resu lts a n d Discu ssion
In tr am olecu lar Deh ydr oflu or in ative Ligan d Cou -
p lin g of [Cp *Rh Cl(d fp p e)]BF 4. It has been estab-
lished that in refluxing ethanol [Cp*RhCl(dfppe)]BF4,
1, undergoes stepwise dehydrofluorinative carbon-
carbon coupling to give [{η5,κP,κP-C5Me4CH2C6F4-2-
P(C6F5)CH2CH2P(C6F5)2}RhCl]BF4, 2, then [{η5,κP,κP-
C5Me3[CH2C6F4-2-P(C6F5)CH2]2-1,3}RhCl]BF4, 3 (Scheme
1).8 We have since found that treatment of 1 with 2
equiv of the strong, non-nucleophilic base 1,8-bis-
(dimethylamino)naphthalene (proton sponge) at room
temperature also yields 3 in quantitative yield. An NMR
tube experiment in CDCl3 indicated that the reaction
is very rapid and had reached completion within 15 min.
We suggest that the mechanism of this reaction involves
initial formation of an η4-fulvene complex, or equivalent
zitterionic carbanion, by loss of a pentamethylcyclopen-
tadienyl proton, followed by nucleophilic attack of the
methylene carbon atom at the ortho position of the
pentafluorophenyl group (Scheme 1). In support of this
mechanism it has previously been established that the
methylene carbon atoms of η4-fulvene rhodium com-
plexes are nucleophilic18 and that polyfluorinated arenes
are susceptible to nucleophilic attack.19 This mechanism
has previously been proposed by Hughes and co-workers
for the similar dehydrofluorinative C-C coupling reac-
tion between the pentamethylcyclopentadienyl and per-
fluorobenzyl ligands of [Cp*Co(CF2C6F5)(PMe3)(CO)]+.20
It has been proposed that proton sponge can also act as
a single-electron donor,21 and the possibility of a mech-
anism involving proton sponge acting in this way was
also considered. However, two observations militate
against such a mechanism. First, the salt [C8H6-
(NMe2)2H]BF4, characterized by single-crystal X-ray
diffraction,22 was obtained on addition of NaBF4 to the
reaction mixture, and second the reaction does not
require the stoichiometric quantity of proton sponge to
proceed to completion. An attempt to prepare 2 by
treatment of 1 with 1 equiv of proton sponge gave 3
quantitatively. Even a ratio of 1:0.1 1:proton sponge
produced predominantly 3 along with some 2. Although
the two products could not be separated, a single crystal
of 2 was obtained from the mixture, allowing the
structure of this intermediate to be determined (vide
14
and (C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2 and that
between [(η5-C5Me4CF3)RhCl(µ-Cl)]2 and Ph2PCHdCH2
to give [{η5,κP-C5Me3(CO2Et)-2-CH2CH2CH2PPh2}RhCl2]7
also occur by coordination of the phosphine and subse-
quent intramolecular reaction, rather than being genu-
ine examples of the third type of synthetic approach to
hybrid cyclopentadienide-phosphine ligands. There are
reports of complexes of other hybrid cyclopentadienyl-
phosphorus(III) ligands formed by intramolecular reac-
tions, namely, the cyclopentadienyl-phosphite complex
[{η5,κP-C5H4C6H4OP(OPh)2}FeI{P(OPh)3}]15 and the cy-
clopentadienyl-phosphide complexes [{η5,κP-C5Me4-
CH2PCH(SiMe3)2P(SiMe3)}Fe(CO)2], [{η5,κP-C5Me4CHd
C(NMe2)PN(CO2R)NHCO2R}Fe(CO)2], and [{η5,κP-C5-
Me4CHdC(NMe2)PHX}Fe(CO)2] (X ) Cr(CO)5 or CpRh-
(CO)).16 As far as we are aware, there are no incontro-
vertible examples of the third synthetic approach.
(5) (a) Bruce, M. I.; Gardner, R. C. F.; Goodall, B. L.; Stone, F. G.
A.; Doedens, R. J .; Moreland, J . A. J . Chem. Soc., Chem. Commun.
1974, 185. (b) Bruce, M. I.; Gardner, R. C. F.; Stone, F. G. A. J . Chem.
Soc., Dalton Trans. 1976, 81.
(6) Barthel-Rosa, L. P.; Catalano, V. J .; Nelson, J . H. J . Chem. Soc.,
Chem. Commun. 1995, 1629.
(7) Barthel-Rosa, L. P.; Catalano, V. J .; Maitra, K.; Nelson, J . H.
Organometallics 1996, 15, 3924.
(8) Atherton, M. J .; Fawcett, J .; Holloway, J . H.; Hope, E. G.;
Karac¸ar, A.; Russell, D. R.; Saunders: G. C. J . Chem. Soc., Dalton
Trans. 1996, 3215.
(9) Atherton, M. J .; Fawcett, J .; Holloway, J . H.; Hope, E. G.; Russell,
D. R.; Saunders, G. C. J . Organomet. Chem. 1999, 582, 163.
(10) Atherton, M. J .; Fawcett, J .; Holloway, J . H.; Hope, E. G.;
Martin, S. M.; Russell, D. R.; Saunders: G. C. J . Organomet. Chem.
1998, 555, 67.
(11) (a) Atherton, M. J .; Holloway, J . H.; Hope, E. G.; Saunders: G.
C. J . Organomet. Chem. 1998, 558, 209. (b) Nieuwenhuyzen, M.;
Saunders, G. C. J . Organomet. Chem. 2000, 595, 292.
(12) Bellabarba, R. M.; Nieuwenhuyzen, M.; Saunders, G. C. J .
Chem. Soc., Dalton Trans. 2001, 512.
(13) Bellabarba, R. M.; Nieuwenhuyzen, M.; Saunders, G. C. Inorg.
Chim. Acta 2001, 323, 78.
(14) Fawcett, J .; Friedrichs, S.; Holloway, J . H.; Hope, E. G.; McKee,
V.; Nieuwenhuyzen, M.; Russell, D. R.; Saunders, G. C. J . Chem. Soc.,
Dalton Trans. 1998, 1477.
(15) Adrianov, V. G.; Chapovskii, Y. A.; Simeon, V. A.; Struchkov,
Y. J . Chem. Soc., Chem. Commun. 1968, 282.
(16) (a) Weber, L.; Kirchhoff, R.; Boese, R.; Stammler, H.-G.;
Neumann B. Organometallics 1993, 12, 731. (b) Weber, L.; Kirchhoff,
R.; Boese, R. Chem. Ber. 1993, 126, 1963. (c) Weber, L.; Kaminski, O.;
Boese, R.; Bla¨ser, D. Organometallics 1995, 14, 820. (d) Weber, L.;
Kirchhoff, R.; Quasdorff, B.; Stammler, H.-G.; Neumann, B. J . Orga-
nomet. Chem. 1997, 529, 329. (e) Weber, L.; Quasdorff, B.; Stammler,
H.-G.; Neumann, B. Chem. Eur. J . 1998, 4, 469. (f) Weber, L.; Scheffer,
M. H.; Stammler, H.-G.; Neumann, B. Inorg. Chim. Acta 1999, 291,
311.
(17) Bellabarba, R. M.; Saunders: G. C. J . Fluorine Chem. 2001,
112, 139.
(18) (a) Gusev, O. V.; Rubeshov, A. Z.; Miguel-Garcia, J . A.; Maitlis,
P. M. Mendeleev Commun. 1991, 121. (b) Gusev, O. V.; Sergeev, S.;
Saez, I. M.; Maitlis, P. M. Organometallics 1994, 13, 2059.
(19) (a) Chambers, R. D. Fluorine in Organic Chemistry; J . Wiley
& Sons: New York, 1973; Chapter 9. (b) Kobrina, L. S. Fluorine Chem.
Rev. 1974, 7, 1. (c) Brooke, G. M. J . Fluorine Chem. 1997, 87, 1.
(20) Hughes, R. P.; Lindner, D. C.; Rheingold, A. L.; Yap, G. P. A.
Organometallics 1996, 15, 5678.
(21) Hughes, R. P.; Kovacik, I.; Lindner, D. C.; Smith, J . M.;
Willemsen, S.; Zhang, D.; Guzei, I. A.; Rheingold, A. L. Organometallics
2001, 20, 3190.
(22) Wozniak, K.; Krygowski, T. M.; Kariuki, B.; J ones, W.; Grech,
E. J . Mol. Struct. 1990, 240, 111.

5728 Organometallics, Vol. 21, No. 26, 2002
Bellabarba et al.
Sch em e 1
infra). The production of 3 from 1 using significantly
less than the stoichiometric quantity can be explained
by fluoride ion, generated by the reaction, acting as the
base. In support of this explanation an NMR tube
In situ NMR experiments have proved useful in
establishing the reaction of 1 with proton sponge and
the intermediacy of 2 in the transformation 1 f 3,8 since
the products containing coupled Cp* and phosphine
ligands possess very different NMR spectroscopic prop-
erties from the starting materials. In particular, δP for
3 is at a higher frequency than that of 1 (by ca. 40 ppm),
and the 1H NMR spectrum of 1 shows a triplet reso-
nance assigned to the Cp* hydrogen atoms, whereas 3
shows two resonances for the hydrogen atoms of the
three methyl groups. The 1H NMR spectra of the
expected products of intramolecular dehydrofluorinative
coupling in the complexes [Cp*RhCl{(C6F5)2-xRxP-L}]+
and [Cp*RhClL{PR3-x(C6F5)x}]+ should contain four
methyl resonances, each integrating as three hydrogen
atoms, by virtue of the stereogenic metal center, as is
found for the tetramethylcyclopentadienyl complexes
[(η5-C5Me4H)RhCl(CNC6H11)PPh3-x(C6F5)x]BF4 (x ) 0 or
1),23 and that from the coupling in the complexes
[Cp*RhCl2{PR3-x(C6F5)x}] should contain two methyl
resonances each integrating for six hydrogen atoms. The
presence of products of coupling in complexes of phos-
phines bearing only one pentafluorophenyl group should
be readily discernible from the presence of four reso-
nances in their 19F spectra, in addition to those of BF4,
rather than the three associated with pentafluorophenyl
groups. Thus, the NMR spectra should provide definitive
evidence as to whether the coupling of the Cp* and
phosphine ligands has occurred, and we therefore
decided to investigate the reactions between the rhod-
ium complexes and proton sponge by in situ NMR
experiments.
reaction between stoichiometric amounts of 1 and Bun
-
4
NF in (CD3)2CO also yielded 3 quantitatively. Further-
more, 3 was obtained in high yield from treatment of 1
with polymer-supported fluoride in CH2Cl2.
The concept of an intramolecular dehydrofluorinative
carbon-carbon coupling reaction coupling two function-
alities by a mechanism involving loss of a proton and
nucleophilic attack by the resulting methylene carbon
at an ortho carbon of a pentafluorophenyl substituent
of a phosphine provides a simple, rational method for
the synthesis of transition metal complexes of other
hybrid cyclopentadienyl-phosphine ligands. The reaction
in Scheme 1 involves a cationic rhodium complex of a
chelating diphosphine in which both phosphorus atoms
bear two pentafluorophenyl substituents. We wished to
determine the criteria for intramolecular dehydroflu-
orinative coupling between Cp* and phosphines in
rhodium(III) complexes by answering the following
questions: (i) is it necessary for the complex to be
cationic? (ii) is it necessary to use a chelating diphos-
phine, or can other types of chelating ligand undergo
coupling? (iii) is it necessary for the phosphorus atom
to bear two pentafluorophenyl groups, or will phos-
phines bearing only one pentafluorophenyl substituent
undergo coupling? and (iv) is it necessary to use chelat-
ing ligands, or will monodentate phosphines undergo
coupling? To answer these questions, we chose to
investigate reactions between the following rhodium-
(III) complexes and proton sponge: (i) cationic com-
plexes of chelating ligands bearing only one bis(penta-
fluorophenyl)phosphine moiety [Cp*RhCl{(C6F5)2P-
L}]+, (ii) a cationic complex of a chelating phosphine
ligand bearing only one pentafluorophenyl substituent,
[Cp*RhCl{(C6F5)RP-L}]+, (iii) neutral complexes of
monodentate phosphines, [Cp*RhCl2{PR3-x(C6F5)x}], and
(iv) cationic complexes of monodentate phosphines,
[Cp*RhCl{PR3-x(C6F5)x}L]+ (L ) two-electron donor).
Syn th esis a n d In tr a m olecu la r Deh yd r oflu or i-
n a tive Liga n d Cou p lin g Stu d y of [Cp *Rh Cl-
{(C6F 5)2P -L}]+. The bifunctional phosphine-thioether
compound (C6F5)2PC6H4SMe-2 (4) was prepared in
80% yield by treating (C6F5)2PBr with Li[C6H4SMe],
formed by addition of nBuLi to 2-bromothioanisole. The
similar phosphine-anisole and phosphine-amine com-
(23) FitzGerald, AÄ . M.; Nieuwenhuyzen, M.; Saunders, G. C. J .
Organomet. Chem. 1999, 584, 206.

Intramolecular Dehydrofluorinative Coupling
Organometallics, Vol. 21, No. 26, 2002 5729
Sch em e 2a
a
(i) BunLi, Et2O; (ii) (C6F5)2PCl; (iii) NaBF4, CH2Cl2/MeOH; (iv) proton sponge, CH2Cl2.
Ta ble 1. NMR Da ta for th e P r od u cts of th e Rea ction s betw een 7, 11, 14a -c, a n d P r oton Sp on ge
starting
material
product
δP (1J RhP/Hz)
∆δP
δH of C5Me4 (4J PH/Hz)
δF of C6F4
7a
8
12
15a
15b
15c
58.6 (150)
53.6 (141)
40.9 (133)
41.7 (132)
59.0 (130)
+28.4
+16.1c
+18.3
+19.5
+24.1
2.17 d (8.9), 1.95 d (3.5), 1.65 s, 1.52 s
2.08 d (6.7), 1.82 d (4.5), 1.34 s, 1.30 s
2.08 d (5.1), 1.82 d (6.2), 1.71 s, 1.52 s
2.12 d (4.6), 1.86 d (6.6), 1.78 s, 1.32 s
2.09 d (4.9), 1.85 d (5.6), 1.70 s, 1.45 s
-119.73, -134.35, -142.43, -151.54
-125.24, -139.91, -149.93, -156.39
-119.22, -136.07, -145.54, -151.82
-120.61, -137.09, -146.30, -152.01
-125.64, -136.22, -146.71, -153.13
11b
14a d
14ba
14ca
a
b
d
Performed in CDCl3. Performed in (CD3)2CO. c Relative to 11a . Performed in CD2Cl2.
pounds (C6F5)2PC6H4OMe-2 (5) and (C6F5)2PC6H4CH2-
NMe-2 (6) were prepared similarly in 90 and 70% yields,
respectively. Compounds 4 and 5 were isolated as white
powders and 6 was isolated as a pale yellow oil, and all
were characterized by mass spectrometry and multi-
nuclear NMR spectroscopy. The 31P{1H} NMR spectra
of all three compounds comprise a quintet at ca. δ -57,
with phosphorus-fluorine coupling of 35-40 Hz. These
data are similar to those of PhP(C6F5)2.24
An NMR tube experiment revealed that on addition
of proton sponge, 7 underwent a similarly rapid and
clean dehydrofluorinative carbon-carbon coupling as 1,
to form 8 (Scheme 2). The NMR data are entirely
consistent with coupling of the Cp* and phosphine
ligands (Table 1). The 31P NMR spectrum showed a
1
resonance with coupling to rhodium at δ 58.6, the H
NMR spectrum contained four resonances assigned to
the four unique methyl groups between δ 0 and 2.5, each
integrating for three hydrogen atoms, and the reso-
nances in the 19F spectrum integrated for 13 atoms
rather than the 14 of 7. Confirmation of the identity of
the product of the coupling reaction, 8, was obtained
by characterization of a sample prepared in 92% by a
preparative scale reaction, including a single-crystal
X-ray structure determination (vide infra). The 1H NMR
spectrum of 8 contained, in addition to the four methyl
resonances, three resonances between δ 7.5 and 8.1,
assigned to the four aromatic hydrogen atoms, and two
resonances showing mutual coupling at δ 4.36 and 3.30,
each integrating for one hydrogen atom. The resonance
at δ 4.36 also shows coupling to phosphorus. These two
resonances are assigned to the nonequivalent hydrogen
atoms of the methylene group which links the Cp* and
C6F4 group and are consistent with resonances observed
for 3.8 The hydrogen atoms of the thiomethyl group give
a singlet resonance at δ 2.60. Compound 8 can exist as
four stereoisomers: the geometry of the cation leads to
only two possibilities of the stereochemistry at rhodium
and phosphorus, RRhSP and SRhRP, but for each there
Treatment of [Cp*RhCl(µ-Cl)]2 with 4 in the presence
of an excess of tetrafluoroborate afforded [Cp*RhCl(4)]-
BF4 (7) as a yellow oil in 79% yield (Scheme 2). Attempts
to crystallize 7 were unsuccessful, and characterization
is based on the NMR data and subsequent reaction. The
31P{1H} NMR spectrum of 7 comprises a doublet of
multiplets at δ 30.2 with a rhodium-phosphorus cou-
pling of 174 Hz, similar to that of 1, which comprises a
doublet of multiplets at δ 35.1 with a coupling of 150
Hz.8 The 19F NMR spectrum of 7, recorded at 298 K and
282 MHz, contains 10 resonances in addition to those
due to BF4-, indicating that there is hindered rotation
about the P-C bonds since all the fluorine atoms of the
P(C6F5)2 moiety are unique. No attempts were made to
determine the stereochemistry at sulfur of 7, and the
conformation suggested in Scheme 2, giving rise to the
R
RhRS and SRhSS pair of enantiomers, is based on
arguments for compound 8 (vide infra). In contrast to
4, neither 5 nor 6 coordinated to the Cp*RhCl fragment.
(24) Nichols, D. I. J . Chem. Soc. A 1969, 1471.

5730 Organometallics, Vol. 21, No. 26, 2002
Bellabarba et al.
Sch em e 3a
are two possibilities of the stereochemistry at sulfur.
1H spectroscopic studies reveal that there is no NOE
correlation between the thiomethyl and Cp* hydrogen
atoms, although NOE correlation between the thiom-
ethyl and two of the aromatic hydrogen atoms is
observed. This observation suggests that just two of the
possible stereoisomers, the enantiomers RRhRSSP and
S
RhSSRP, are present in solution. This is in agreement
with the X-ray structure (vide infra). In these enanti-
omers the Cp* and methyl groups are trans groups on
the five-membered RhSC2P ring, and this is expected
to be the sterically favored conformation. The possibility
of the singlet resonance arising from the averaging of
resonances from diastereoisomers was examined by
variable-temperature 1H NMR spectroscopy. Down to
228 K, the lowest temperature at which spectra were
recorded, no change in the resonance was observed, and
we suggest that the stereochemistry at the sulfur in 8
(and also in the compounds 7, 11a , 11b, and 12) is such
that the Cp* and methyl group are trans.
Syn th esis a n d In tr a m olecu la r Deh yd r oflu or i-
n a tive Liga n d Cou p lin g Stu d y of [Cp *Rh Cl{(C6F 5)-
RP -L}]+. The reaction between PhPCl2 and C6F5MgBr
in diethyl ether produced a mixture of PhP(C6F5)Cl (9a )
and PhP(C6F5)Br (9b) as a colorless solid.25 The mixture
was characterized by NMR spectroscopy. The 31P{1H}
NMR spectrum, which has not been reported previously,
shows two triplets at δ 57.3 and 41.1, both with coupling
3
constants, J PF, of 49 Hz. By analogy with the 31P{1H}
NMR spectra of (C6F5)2PX and (C6F5)PX2, in which the
resonances for chlorides are at higher frequency to those
of the respective bromides,26 the former resonance is
assigned to 9a and the latter to 9b. The 19F NMR
spectrum supports the presence of two compounds.
Although the meta and para fluorine resonances are
coincident for the two compounds, the ortho fluorine
resonances occur at δ -129.13 for 9a and -127.53 for
9b. The ratio of 9a to 9b was determined to be 1:3 from
these spectra. Treatment of the mixture of 9a and 9b
with Li[C6H4SMe] gave the bifunctional phosphine-
thioether compound PhP(C6F5)C6H4SMe-2 (10) in ca.
50% yield. The 31P{1H} NMR spectrum of 10 comprises
a
(i) BunLi, Et2O; (ii) (C6F5)PhPBr/Cl; (iii) NaBF4, CH2Cl2/
MeOH; (iv) proton sponge.
presumably the reverse can occur, the rate of isomer-
ization is slow and the equilibrium may not have been
established before the solid was isolated nor in the NMR
tube. The 31P{1H} NMR spectrum exhibits two doublet
resonances at δ 37.5 and 55.6, both with coupling to
rhodium of ca. 145 Hz. The former resonance is assigned
1
to 11a and is similar to that of 1 (δP 35.1, J RhP ) 151
Hz).8 The latter resonance is assigned to 11b and is
comparable to that of [Cp*RhCl(dppe)]BF4 (δP 66.2,
1J RhP ) 151 Hz).27 Both 11a and 11b show three
3
resonances in addition to those due to BF4 in the 19F
a triplet at δ -32.6 with a value of J PF of 37 Hz,
-
comparable with the data for Ph2P(C6F5).24
NMR spectrum.
Treatment of [Cp*RhCl(µ-Cl)]2 with compound 10 in
the presence of an excess of tetrafluoroborate yielded a
mixture of two isomers of [Cp*RhCl(10)]BF4 in ca. 1:1
ratio (Scheme 3). The isomers were fully characterized
by multinuclear spectroscopy, and subsequent reaction
(vida infra), as 11a and 11b. If, as suggested for 8, the
Cp* and methyl groups are trans groups on the RhSC2P
ring, then the isomers are racemic diastereoisomers,
differing in the relative positions of the Cp* and C6F5
groups. In 11a these groups are cis and in 11b trans.
The NMR data indicate that the relative proportions of
11a and 11b are 43 and 57%, respectively. Although
the ratio is consistent with the greater steric congestion
in 11a , it is not known whether the mixture is in
equilibrium or the ratio is a consequence of the kinetics
of the coordination of 10 to the [Cp*RhCl]+ fragment.
Although 11b can isomerize to 11a (vide infra), and
The reaction between proton sponge and the mixture
of 11a and 11b was performed in (CD3)2CO in an NMR
tube at room temperature. A rapid reaction was ob-
served by 31P{1H} NMR spectroscopy, which showed a
decrease in intensity of the doublet resonance of 11a
and the appearance of a new doublet at δ 53.6 with a
1
coupling to rhodium of 141 Hz. The H and 19F NMR
spectra also showed a decrease in intensity of the
resonances assigned to 11a and the presence of new
resonances (Table 1) consistent with coupling of the Cp*
and phosphine ligands to give 12 (Scheme 3). In addition
to the resonances assigned to C5Me4, the 1H NMR
spectrum possesses mutually coupled resonances at δ
4.33 and 3.49 characteristic of the nonequivalent hy-
drogen atoms of the methylene group. The former
resonance appears as a triplet due to coupling to
phosphorus of the same magnitude as the H-H coupling
(17.2 Hz). The latter resonance is a doublet. The
(25) (a) Fild, M.; Glemser, O.; Hollenberg, I. Z. Naturforsch., Teil B
1966, 21, 920. (b) Cowley, A. H.; Cushner, M.; Fild, M.; Gibson, J . A.
Inorg. Chem. 1975, 14, 1851.
(27) Hope, E. G.; Kemmitt, R. D. W.; Stuart, A. M. J . Chem. Soc.,
Dalton Trans. 1998, 3765.
(26) Ali, R.; Dillon, K. B. J . Chem. Soc., Dalton Trans. 1990, 2593.

Intramolecular Dehydrofluorinative Coupling
Organometallics, Vol. 21, No. 26, 2002 5731
thiomethyl resonance occurs at δ 3.02 Over time a
decrease in the intensity of the resonances assigned to
11b and a concomitant increase in the intensity of those
of 12 was observed. The relative integrations of the
resonances assigned to 11a , 11b, and 12 were ca. 1:3:2
after 3.5 h, ca. 0:1:3 after 19 h, ca. 0:1:5 after 28 h, and
ca. 0:1:10 after 50 h. Only resonances assigned to 12
and byproducts were observed after 144 h. The NMR
data are consistent with a rapid coupling of the Cp* and
phosphine ligands of 11a and a relatively slow isomer-
ization of 11b to 11a . Possible mechanisms of the
isomerization include (i) dissociation of the thioether
group rotation about the Rh-P bond and recoordination,
(ii) dissociation of the phosphine, rotation about the
Rh-S bond, and recoordination, (iii) dissociation of the
ligand 10 and recoordination to give 11a , (iv) dissocia-
tion of chloride and recoordination from the opposite
face of the Cp*Rh(10) fragment,28 (v) dissociation of
chloride from one cation and attack at another cation
of 11b trans to the coordinated chloride, followed by
dissociation of the appropriate chloride,29 and (vi) dis-
sociation of the phosphine, inversion at phosphorus, and
recoordination (Scheme 4). Mechanisms (i)-(v) result
in inversion of chirality only at rhodium, whereas
mechanism (vi) results in inversion of chirality only at
phosphorus. The isomerization of [Cp*RhCl(R-Ph2-
PCHMeCH2PPh2)]Cl, which occurs only at elevated
temperature, was proposed to occur by mechanism (v).29
The largest difference in coordination about rhodium
between 11b and [Cp*RhCl(R-Ph2PCHMeCH2PPh2)]Cl
is the presence of an Rh-S bond in the former instead
of the Rh-P bond of the latter. We suggest that it is
this difference that accounts for the difference in
isomerization rates at room temperature and reason
that (i) is the dominant mechanism of isomerization of
11b. If the other mechanisms are important, then the
isomerization of 11b might be expected to occur only
under conditions similar to that of [Cp*RhCl(R-Ph2-
PCHMeCH2PPh2)]Cl.
Syn th esis a n d In tr a m olecu la r Deh yd r oflu or i-
n a tive Liga n d Cou p lin g Stu d y of [Cp *Rh Cl{P R′2-
(C6F 5)}L]+. Attempts to prepare the bis(phosphine)
complex cations [Cp*RhCl{PR2(C6F5)}2]+ were unsuc-
cessful, presumably for steric reasons. Salts of the
cations [Cp*RhCl{R2P(C6F5)}(CNR′)]+ (R ) phenyl, R′
) phenyl 14a or cyclohexyl, 14b; R ) ethyl, R′ ) cyclo-
hexyl, 14c) were prepared by treatment of [Cp*RhCl2-
{PR2(C6F5)}] with an excess of sodium tetrafluoroborate
and the appropriate isonitrile (Scheme 5). The salt 14a
was obtained as an orange solid, but 14b and 14c were
obtained as yellow oils, which, despite repeated at-
tempts, failed to produce solid products and elemental
analyses could not be obtained. Characterization of
these two salts was based on the NMR spectroscopic
data and comparisons with 14a and similar com-
pounds.23,30 The 31P{1H} NMR spectra show doublet
resonances at ca. δ 22 for 14a and 14b and δ 34.9 for
14c. All three show coupling to rhodium of ca. 130 Hz,
and that of 14c also to fluorine of 11 Hz. The small shifts
of δP to higher frequency on going from [Cp*RhCl2{PR2-
(C6F5}] to [Cp*RhCl{PR2(C6F5)}(CNR′)]+ are consistent
with those of the tetramethylcyclopentadienyl ana-
logues.23
NMR tube experiments revealed that on addition of
proton sponge, 14a -c underwent dehydrofluorinative
carbon-carbon coupling to form 15a -c (Scheme 5). The
NMR data are entirely consistent with coupling of the
Cp* and phosphine ligands (Table 1). The 31P NMR
spectra showed resonances, with coupling to rhodium
of ca. 130 Hz, at ca. 20 ppm higher frequency than the
starting materials. The resonance of 15c also shows a
6 Hz coupling to one fluorine atom. The 1H NMR spectra
contained four resonances assigned to the four unique
methyl groups between δ 1 and 2.5. The methylene
hydrogen resonances of 15b appear as two doublets of
doublets at δ 3.64 and 3.30 with a mutual coupling of
16.0 Hz and couplings to phosphorus of 11.8 and 5.6 Hz,
respectively. For 15a and 15c only one methylene
resonance is observed; the other is presumably obscured
by broad resonances due to protonated proton sponge
at 2.6-3.0 ppm. That of 15a appears as a triplet at δ
3.64 with a coupling of 8.1 Hz to phosphorus and the
other methylene hydrogen, and that of 15c appears as
a doublet at δ 3.87 with a coupling of 8.3 Hz. The rates
of the reactions for 14a -14c are considerably slower
than those for 1, 7, and 11a . In each case the ratio of
starting material to product was ca. 1:1 after 24 h. The
reactions of 14b and 14c were clean, and the spectra
indicated that 15b and 15c were formed almost quan-
titatively after 68 and 45 h, respectively. In contrast the
reaction between 14a and proton sponge gave varying
amounts of other fluorine- and phosphorus-containing
compounds depending on the solvent. In chloroform at
least three other phosphorus- and fluorine-containing
compounds were formed in significant amounts (10-
30% of the total product), although in dichloromethane
the formation of these other products was significantly
reduced. The slower rates of dehydrofluorinative carbon-
carbon coupling for 14a -c in comparison to 1, 7, and
11a can be explained by rotation about the Rh-P bond
in the former group of compounds. In 1, 7, and 11a the
Syn th esis a n d In tr a m olecu la r Deh yd r oflu or i-
n a tive Liga n d Cou p lin g Stu d y of Cp *Rh Cl2{P R2-
(C6F 5)}. The neutral monodentate phosphine complex
[Cp*RhCl2{PPh2(C6F5)}] (13a ) has been described previ-
ously.10 The new complex [Cp*RhCl2{PEt2(C6F5)}] (13b)
was prepared from [Cp*RhCl(µ-Cl)]2 and PEt2(C6F5)
(Scheme 5). The 31P{1H} NMR spectrum of 13b pos-
sesses a doublet of triplets resonance, arising from
coupling to rhodium and the ortho fluorine atom, at
higher frequency by ca. 10 ppm than the resonances of
13a (δP 18.8)10 and [(η5-C5Me4H)RhCl2{PPh2(C6F5)}] (δP
21.4).23 The coupling to rhodium is ca. 145 Hz for all
three compounds. The formulation of 13b was confirmed
by single-crystal X-ray diffraction (vide infra). Neither
13a nor 13b underwent a reaction with proton sponge,
even over prolonged periods.
We have previously established that phosphines
containing two or more phenyl rings bearing two ortho
fluorine substituents are too bulky to coordinate to the
Cp*RhCl2 fragment,10,30 and compounds of formulation
[Cp*RhCl2{PR(C6F5)2}] could not be prepared.
(28) Davies, D. L.; Fawcett, J .; Garratt, S. A.; Russell, D. R.
Organometallics 2001, 20, 3029.
(29) Carmona, D.; Lahoz, F. J ., Oro, L. A.; Lamata, M. P.; Viguri,
F.; San J ose´, E. Organometallics 1996, 15, 2961.
(30) Corcoran, C.; Friedrichs, S.; Fawcett, J .; Holloway, J . H.; Hope,
E. G.; Russell, D. R.; Saunders, G. C.; Stuart, A. M. J . Chem. Soc.,
Dalton Trans. 2000, 161.

5732 Organometallics, Vol. 21, No. 26, 2002
Bellabarba et al.
Sch em e 4
two reacting groups are held in close proximity, which
is not the case for 14a -c. The slow rate of the reaction
would also allow the possibility of intermolecular reac-
tions with, for example, solvent and lead to nonquan-
titative formation of the ligand-coupled product, as
observed for 14a .
X-r a y Diffr a ction Stu d ies of 2, 8, a n d 13b. The
structures of compounds 2, 8, and 13b were determined

Intramolecular Dehydrofluorinative Coupling
Organometallics, Vol. 21, No. 26, 2002 5733
Sch em e 5a
a
(i) R′NC, NaBF4, CH2Cl2/MeOH; (ii) proton sponge.
Ta ble 2. Cr ysta l a n d Str u ctu r e Refin em en t Da ta
2‚2CHCl3
8‚3CHCl3
13b
formula
M
C
36H16BClF23P2Rh.2CHCl3
C
29H21BClF13PRhS.3CHCl3
C
20H25Cl2F5PRh
1337.35
1186.76
565.18
T, K
153(2)
153(2)
153(2)
cryst syst
space group
a, Å
b, Å
c, Å
triclinic
P1h
triclinic
P1h
monoclinic
P21/c
8.267(4)
35.806(19)
8.288(4)
90
116.566(8)
90
2194(2)
12.2595(8)
14.1355(9)
14.7311(10)
86.1140(10)
69.5290(10)
75.0530(10)
2310.0(3)
2
11.6484(9)
11.7516(10)
17.7351(14)
93.233(2)
102.5490(10)
112.3060(10)
2166.3(3)
2
R, deg
â, deg
γ, deg
U, Å3
Z
4
D
calc, g cm-3
1.923
1.819
1.768
λ, Å
0.71073
0.969
28.73
0.71073
1.179
28.66
0.71073
1.150
22.50
µ, mm-1
θmax, deg
cryst dimens, mm3
no. of reflns collected
no. of ind reflns
0.38 × 0.28 × 0.24
0.48 × 0.31 × 0.19
0.35 × 0.28 × 0.20
20235
14538
9676
10397 (Rint ) 0.0683)
6753
0.0507, 0.1011
0.0830, 0.1144
0.926
8998 (Rint ) 0.0521)
6357
0.0470, 0.1100
0.0701, 0.1204
0.935
2860 (Rint ) 0.1421)
1508
0.0916, 0.2242
0.1511, 0.2564
0.953
no. of obsd reflns [I > 2σ(I)]
R1, wR2 [I > 2σ(I)]
R1, wR2 (all data)
goodness-of-fit
largest ∆F, e Å-3
1.182, -1.015
0.728, -0.674
2.860, -1.110
by single-crystal X-ray diffraction. The crystal and
structure refinement data are given in Table 2.
Both 2 and 8 are racemic, and in both structures the
two enantiomers are contained within the unit cell. The
structure of the RRhSP cation of 2 is shown in Figure 1,
and that of the RRhRSSP enantiomer of the cation of 8
is shown in Figure 2.
A number of structural changes occur on coupling Cp*
and phosphine ligands through a tetrafluorophenylene
bridge. There is a reduction in the Cp†-Rh (Cp† repre-
sents the centroid of the C5 ring) and Rh-P distances
and the Cp†-Rh-P and P-Rh-P angles, but there is
little effect on the Rh-Cl distance. The Cp†-Rh dis-
tances of the coupled products 2, 3 (1.837(1) Å),31 and
the bromo analogue of 3 (1.829(7) Å)9 are identical
within experimental error, but significantly shorter than
that of 1, which is identical to those of salts of [Cp*RhCl-
(P2)]+, where P2 ) (C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2
(1.868(4) Å)14 and R-Ph2PCH(Me)CH2PPh2 (1.873(2)
Å).29 The Cp†-Rh of 8 is considerably shorter than those
of 2 and 3, which is presumably due to the difference
between coordination to phosphine and thioether. The
mean Rh-C distances of [Cp*RhCl(thioether)]+ com-
pounds range from 2.15 to 2.17 Å,32 that of 8 is 2.185
Å, and those of 131 and 2 are 2.22 and 2.21 Å, respec-
tively. The Rh-P distances for uncoupled phosphines
range from 2.33 to 2.36 Å, whereas those for the coupled
(31) Atherton, M. J .; Fawcett, J .; Holloway, J . H.; Hope, E. G.;
Karac¸ar, A.; Russell, D. R.; Saunders, G. C. J . Chem. Soc., Chem
Commun. 1995, 191.

5734 Organometallics, Vol. 21, No. 26, 2002
Bellabarba et al.
of ca. 3-4°. The P-Rh-P angle of 1 is ca. 3° smaller
than those of 2 and 3, which are similar. The Rh-P
distance and Cp†-Rh-P and P-Rh-P angles are
consistent with those of similar uncoupled14,29 and
coupled compounds.9 The Rh-S distance of 8 is signifi-
cantly shorter than those found in [Cp*RhCl(thioether)]+
compounds (2.3645(9) to 2.4164(19) Å),32 all of which
comprise aliphatic thioethers, and this may be a con-
sequence of the phenylene backbone of the phosphine-
thioether moiety rather than coupling of the phosphine
to the Cp* ligand.
The cyclopentadienyl ring of 2 shows distortion from
a symmetrical η5-C5 ring toward an η3,η2-enyl-ene33 form
with the central atom of the enyl moiety attached to the
tetrafluorobenzyl group. The Rh-C(1), Rh-C(4), and
Rh-C(5) distances, ranging from 2.163(4) to 2.184(4) Å,
are significantly shorter than the Rh-C(2) and Rh-C(3)
distances (2.256(4) and 2.270(4) Å), which are ap-
proximately trans to P(1). Consistent with this distor-
tion, the C(2)-C(3) (ene) distance (1.412(6) Å) is sig-
nificantly shorter than the C(3)-C(4) distance (1.453(5)
Å), although within 3σ of the C(2)-C(5) distance (1.444-
(5) Å). The enyl C(1)-C(4) and C(1)-C(5) distances are
within 3σ of all other internal C-C ring distances. A
similar distortion of the cyclopentadienyl ring is found
in 8. The Rh-C(3) and Rh-C(4) distances (trans to
phosphine) of 2.241(4) and 2.219(4) Å, respectively, are
up to 0.1 Å longer than Rh-C(1), Rh-C(2), and Rh-
C(5) (2.134(4) to 2.171(4) Å), and the C(3)-C(4) (ene)
distance (1.399(6) Å) is ca. 0.4 Å shorter than C(2)-C(3)
and C(4)-C(5). The enyl C(1)-C(2) distance is within
3σ of all other internal C-C ring distances. The other
enyl bond distance, C(1)-C(5), is longer than C(3)-C(4)
but within experimental error of the others.
F igu r e 1. Structure of the RRhSP enantiomer of the cation
of [{η5,κP,κP-C5Me4CH2C6F4-2-P(C6F5)CH2CH2P(C6F5)2}-
RhCl]BF4 (2). Thermal ellipsoids are at the 30% probability
level. Hydrogen atoms are omitted for clarity. Cp†-Rh(1)
1.842(4) Å; Rh(1)-P(1) 2.2726(11) Å; Rh(1)-P(2) 2.3306-
(11) Å; Rh(1)-Cl(1) 2.3879(10) Å; C(1)-C(10) 1.505(5) Å,
C-CH3(mean) 1.491(6) Å; P(1)-C(11A) 1.825(4) Å; P(1)-
C(11B) 1.831(4) Å; P(1)-C(11) 1.831(4) Å; P(2)-C(21A)
1.837(4) Å; P(2)-C(21B) 1.838(4) Å; P(2)-C(12) 1.847(4)
Å; Cp†-Rh(1)-P(1) 124.2(1)°; Cp†-Rh(1)-P(2) 132.6(1)°;
Cp†-Rh(1)-Cl(1) 123.5(1)°; P(1)-Rh-P(2) 87.18(4)°; P(1)-
Rh-Cl(1) 88.38(4)°; P(2)-Rh-Cl(1) 87.73(4)°.
The structure of 13b is shown in Figure 3. The
complex shows the expected three-legged piano stool
geometry about rhodium. The C5 ring is symmetrical
with identical Rh-C, C-C, and C-CH3 distances. The
mean Rh-C, Rh-P, and Rh-Cl distances lie within the
ranges of those of other Cp*RhCl2(phosphine) complexes
(2.17-2.20, 2.29-2.38, and 2.36-2.42 Å, respectively).34
The three Cl-Rh-X (X ) P or Cl) angles of 13b are
less than 90°, which is in contrast to other Cp*RhCl2-
(phosphine) complexes, in which at least one Cl-Rh-X
angle is greater than 90°. However, the angles are all
within the range found for similar complexes (84.8-
(32) (a) Bell, M. N.; Blake, A. J .; Schro¨der, M.; Stephenson, T. A. J .
Chem. Soc., Chem. Commun. 1986, 471. (b) Albrecht, M.; Scheiring,
T.; Sixt, T.; Kaim, W. J . Organomet. Chem. 2000, 596, 84. (c)
Valderama, M.; Contreras, R.; Arancibia, V.; Boys, D. J . Organomet.
Chem. 2001, 620, 256.
(33) (a) Dahl, L. F.; Wei, C. H. Inorg. Chem. 1963, 2, 713. (b)
Bennett, M. J .; Churchill, M. R.; Gerloch, M.; Mason, R. Nature 1964,
201, 1318. (c) Mingos, D. M. P.; Minshall, P. C.; Hursthouse, M. B.;
Malik, K. M. A.; Willoughby, S. D. J . Organomet. Chem. 1979, 181,
169. (d) Rigby, W.; Lee, H. B.; Bailey, P. M.; McCleverty, J . A.; Maitlis,
P. M. J . Chem. Soc., Dalton Trans. 1979, 387.
(34) (a) Dapporto, P.; Stoppioni, P.; Maitlis, P. M. J . Organomet.
Chem. 1982, 236, 273. (b) Brost, R. D.; Bruce, G. C.; Grundy, S. L.;
Stobart, S. R. Inorg. Chem. 1993, 32, 5195. (c) Keim, W.; Kraneburg,
P.; Dahmen, G.; Deckers, G.; Englert, U.; Linn, K.; Spaniol, T. P.;
Raabe, G.; Kru¨ger, C. Organometallics 1994, 13, 3085. (d) Han, X.-H.;
Yamamoto, Y. J . Organomet. Chem. 1988, 561, 157. (e) Fawcett, J .;
Hope, E. G.; Kemmitt, R. D. W.; Paige, D. R.; Russell, D. R.; Stuart,
A. M. J . Chem. Soc., Dalton Trans. 1998, 3751. (f) Ma, J .-F.; Yamamoto,
Y. J . Organomet. Chem. 1999, 574, 148. (g) Ve´zina, M.; Gagnon, J .;
Villeneuve, K.; Drouin, M.; Harvey, P. D. J . Chem. Soc., Chem.
Commun. 2000, 1073. (h) Yamamoto, Y.; Sugawara, K. J . Chem. Soc.,
Dalton Trans. 2000, 2896. (i) Durran, S. E.; Smith, M. B.; Slawin, A.
M. Z.; Steed, J . W. J . Chem. Soc., Dalton Trans. 2000, 2771.
F igu r e 2. Structure of the RRhRSSP enantiomer of the
cation of [{η5,κP,κS-C5Me4CH2C6F4-2-P(C6F5)C6H4SMe}-
RhCl]BF4 (8). Thermal ellipsoids are at the 30% probability
level. Hydrogen atoms are omitted for clarity. Cp†-Rh(1)
1.815(4) Å; Rh(1)-P(1) 2.2540(10) Å; Rh(1)-S(7A) 2.3502-
(10) Å; Rh(1)-Cl(1) 2.3719(11) Å; C(1)-C(6) 1.496(5) Å;
C-CH3(mean) 1.498(6) Å; P(1)-C(11) 1.825(4) Å; P(1)-
C(21) 1.825(4) Å; P(1)-C(1A) 1.818(4) Å; S(7A)-C(6A)
1.793(4) Å; S(7A)-C(8A) 1.801(4) Å; Cp†-Rh-P(1) 126.6-
(1)°; Cp†-Rh-S(7A) 121.7(1)°; Cp†-Rh-Cl(1) 124.4(1)°;
P(1)-Rh(1)-S(7A) 86.10(4)°; P(1)-Rh(1)-Cl(1) 93.19(4)°;
Cl(1)-Rh(1)-S(7A) 94.71(4)°.
phosphines are considerably shorter, 2.25 to 2.28 Å. The
Rh-Cl distance is the same within experimental error
for 1-3 and 8. The Cp†-Rh-P angles are >130° for
uncoupled phosphines, but are significantly smaller for
coupled phosphines (<127°). Both groups show a range

Intramolecular Dehydrofluorinative Coupling
Organometallics, Vol. 21, No. 26, 2002 5735
presence of the positive charge increases the acidity
enough to facilitate the reaction. It is necessary for the
phosphine to bear only one pentafluorophenyl group.
The reaction is rapid (within 15 min) in complexes
where a pentafluorophenyl group is held close to the Cp*
ligand. This occurs in complexes of chelating ligands
with a P(C6F5)2 functionality (1, 7) and that with a PPh-
(C6F5) functionality where the pentafluorophenyl group
is in a cis arrangement with the Cp* about the Rh-P
bond (11a ). Where only a trans arrangement of pen-
tafluorophenyl and Cp* exists (as in 11b) the presence
of a labile group in the chelating ligand can allow
isomerization to a complex with a cis arrangement
followed by intramolecular coupling to occur. Thus, the
coupling of Cp* to ligands such as (C6F5)PhPC6H4SMe-2
(10) leads to only one product. Coupling between Cp*
and monodentate phosphines occurs at a much slower
rate than reactions involving chelating ligands. This is
a consequence of rotation about the Rh-P bond, which
allows the pentafluorophenyl group to be distant to the
Cp* ligand.
F igu r e 3. Structure of [Cp*RhCl2{PEt2(C6F5)}] (13b).
Thermal ellipsoids are at the 30% probability level. Hy-
drogen atoms are omitted for clarity. Cp†-Rh(1) 1.82(2) Å;
Rh(1)-P(1) 2.310(5) Å; Rh(1)-Cl(1) 2.402(4) Å; Rh(1)-Cl-
(2) 2.389(5) Å; Rh-C (mean) 2.180(16) Å; P(1)-C(11) 1.825-
(16) Å; P(1)-C(21) 1.837(16) Å; P(1)-C(31) 1.880(15) Å;
Cp†-Rh(1)-P(1) 132.2(5)°; Cp†-Rh(1)-Cl(1) 123.6(5)°; Cp†-
Rh(1)-Cl(2) 123.1(5)°; P(1)-Rh(1)-Cl(1) 87.25(15)°; P(1)-
Rh(1)-Cl(2) 89.36(15)°; Cl(1)-Rh(1)-Cl(2) 88.44(17)°; Rh-
(1)-P(1)-C(11) 115.1(5)°; Rh(1)-P(1)-C(21) 117.2(6)°;
Rh(1)-P(1)-C(31) 115.4(5)°; C(11)-P(1)-C(21) 103.1(7)°;
C(11)-P(1)-C(31) 101.8(7)°; C(21)-P(1)-C(31) 102.2(7)°.
Exp er im en ta l Section
Gen er a l P r oced u r es. The preparations of 4, 5, 6, 9a and
9b, and 10 were carried out under dinitrogen using standard
Schlenk line techniques and diethyl ether dried by distillation
from sodium/benzophenone under dinitrogen. PhPCl2 and Ph2-
PCl (Aldrich) were distilled under dinitrogen before use. For
all other preparations and NMR tube reactions no special
precautions were taken and reagent grade solvents were used
as supplied. The compounds [Cp*RhCl(µ-Cl)]2, NaBF4, proton
sponge, polymer-supported fluoride (fluoride on Amberlyst
A-26), 2-bromothioanisole, 2-bromoanisole, N,N-dimethylben-
zylamine, Et2PCl (Aldrich), and C6F5Br (Fluorochem) were
used as supplied. (C6F5)2PBr,26 13a ,10 and PhNC35 were
prepared as described. PPh2(C6F5)36 and PEt2(C6F5)37 were
prepared from Ph2PCl and Et2PCl, respectively, as described
for similar compounds.25 The 1H, 19F, and 31P NMR spectra
were recorded using Bruker DPX300 and 500 spectrometers.
1H NMR (300.13 and 500.13 MHz) were referenced internally
using the residual protio solvent resonance relative to SiMe4
(δ 0), 19F NMR (282.26 MHz) externally to CFCl3 (δ 0), and
31P NMR (121.45 MHz) externally to 85% H3PO4 (δ 0). All
chemical shifts are quoted in δ (ppm), using the high-frequency
positive convention, and coupling constants are in Hz. EI mass
spectra were recorded on a VG Autospec X series mass
spectrometer. Elemental analyses were carried out by A.S.E.P.,
The School of Chemistry, Queen’s University Belfast.
93.9°) and the sum of these angles for 13b, 265.0(5)°, is
similar to that found for Cp*RhCl2PPh2CH2CH(C6H4-
CO2Me-4)C6H3(OMe-2)(OH-6), 265.5(6)°.34h The Cp†-
Rh-P angle is ca. 9° larger than the Cp†-Rh-Cl angles,
which is consistent with the greater bulk of the phos-
phine group in comparison to chloride. In comparison,
the Cp†-Rh-P and Cp†-Rh-Cl angles of the tri-
arylphosphine complex Cp*RhCl2P{C6H4(CF2)5CF3-4}3
are respectively ca. 2.5° larger and 1-3° smaller.34e The
phosphine group of 13b possesses pseudo-C3 symmetry
about the Rh-P axis with similar Rh-P-C and C-P-C
angles and P-C distances that are identical within
experimental error.
Con clu sion s
Intramolecular dehydrofluorinative carbon-carbon
coupling provides a convenient method of preparing
rhodium(III) complexes of hybrid cyclopentadienide-
phosphine ligands. Results of studies of this reaction
for 1, which forms 2 then 3, are consistent with a
mechanism proposed by Hughes and co-workers for a
cobalt(III) complex.20 Loss of a proton from the Cp*
ligand affords an η4-fulvene complex or equivalent
carbanion-containing zwitterion, which contains a nu-
cleophilic methylene carbon (carbanion) which attacks
a pentafluorophenyl group at an ortho position, leading
to loss of fluoride and formation of a carbon-carbon
bond. The reaction occurs rapidly in the presence of
proton sponge, which acts as a base, and also fluoride,
which is generated by the reaction. Thus reaction occurs
on addition of much less than the stoichiometric quan-
tity of proton sponge.
(C6F 5)2P C6H4SMe-2, 4. A solution of BunLi in hexane (1.5
cm3, 1.6 M) was added to 2-bromothioanisole (0.50 g, 2.4 mmol)
in diethyl ether (50 cm3) at 0 °C. After stirring for 1 h the
solution was added dropwise to (C6F5)2PBr (1.07 g, 2.4 mmol)
at 0 °C. The solution was allowed to warm to room temperature
overnight. Water (ca. 2 cm3) was added, and the volatiles were
removed under reduced pressure. The product was obtained
as a white solid on recrystallization from methanol. Yield: 0.82
1
g (80%). H NMR (CDCl3): δ 7.44 (m, 2H, C6H4), 7.20 (m, 1H,
C6H4), 7.08 (m, 1H, C6H4), 2.51 (s, 3H, Me). 19F (CDCl3): δ
3
-129.15 (m, 4F, o-C6F5), -149.40 (t, J FF ) 21.2 Hz, 2F,
p-C6F5), -160.30 (m, 4F, m-C6F5). 31P (CDCl3): δ -57.4
3
(quintet, J PF ) 37 Hz). MS(EI) m/z: 487 (25%, [M - H]+),
472 (100%, [M - CH4]+); found for [M - H]+ 486.97691.
NMR studies have revealed the necessary conditions
for the intramolecular dehydrofluorinative coupling of
Cp* and phosphine ligands of rhodium(III) complexes.
The complex must be cationic. We suggest that in
neutral complexes the acidity of the hydrogen atoms of
the Cp* complex is not sufficient for reaction, but the
C
19H6F10PS requires 486.97682.
(35) Rigby, J . H.; Laurent, S. J . Org. Chem. 1998, 63, 6742.
(36) Kemmitt, R. D. W.; Nichols, D. I.; Peacock, R. D. J . Chem. Soc.
A 1968, 2149.
(37) Fild, M.; Glemser, O.; Hollenberg, I. Naturwissenschaften 1965,
52, 590.

5736 Organometallics, Vol. 21, No. 26, 2002
Bellabarba et al.
(C6F 5)2P C6H4OMe-2, 5. Compound 5 was prepared simi-
larly to Ph2PC6H4OMe-238 from 2-bromoanisole (0.33 cm3, 2.6
mmol) and (C6F5)2PBr (1.15 g, 2.6 mmol). Yield: 0.97 g (90%).
1H NMR (CDCl3): δ 7.43 (m, 1H, C6H4), 6.95 (m, 3H, C6H4),
3.83 (s, 3H, OMe). 19F (CDCl3): δ -129.95 (m, 4F, o-C6F5),
(m, 2H), 7.10 (m, 1H), 6.98 (m, 1H), 2.48 (s, 3H, Me). 19F (282.4
3
MHz, CDCl3): δ -128.30 (m, 2F, o-C6F5), -150.69 (t, J FF
)
20.0 Hz, 1F, p-C6F5), -160.95 (m, 2F, m-C6F5). 31P (CDCl3): δ
3
-32.6 (t, J PF ) 37 Hz).
[Cp *Rh Cl{(C6F 5)P h P C6H4SMe-2}]BF 4, 11. [Cp*RhCl(µ-
Cl)]2 (0.14 g, 0.22 mmol), 10 (0.175 g, 0.44 mmol), and NaBF4
(0.11 g, 1.0 mmol) were treated as for the preparation of 7. A
mixture of 43% 11a and 57% 11b was obtained as an orange
microcrystalline solid containing 0.33 molecule of dichlo-
romethane. Yield: 0.35 g (100%). 1H NMR [(CD3)2CO]: δ 7.4-
8.2 (m, 9H, C6H4 and C6H5), 5.56 (s, 0.66H, CH2Cl2), 3.09 (s,
1.3H, SMe 11a ), 2.96 (s, 1.7H, SMe 11b), 1.73 (d, J PH ) 4.1
Hz, 6.45H, Cp* 11a ), 1.66 (d, J PH ) 4.0 Hz, 8.55H, Cp* 11b).
19F [(CD3)2CO]: δ -125.34 (d, J ) 16.3 Hz, 1.1F, o-C6F5 11b),
-127.58 (br s, 0.9F, o-C6F5 11a ), -148.99 (m, 0.4F, p-C6F5 11a ),
-150.79 (m, 0.6F, p-C6F5 11b), -152.95 (s, 0.8F, 10BF4-),
-153.00 (s, 3.2F, 11BF4-), -161.51 (m, 0.9F, m-C6F5, 11a ),
-163.31 (m, 1.1F, m-C6F5 11b). 31P (121.5 MHz, (CD3)2CO):
3
-150.11 (t, J FF ) 19.8 Hz, 2F, p-C6F5), -160.78 (m, 4F,
m-C6F5). 31P (CDCl3): δ -57.0 (quintet, 3J PF ) 36 Hz). MS(EI)
m/z: 472 (87%, M+), 365 (100%, [M - C6H4OCH3]+); found for
M+ 472.00897. C19H7F10PO requires 472.00749.
(C6F 5)2P C6H4CH2NMe2-2, 6. Compound 6 was prepared as
described for 4 from N,N-dimethylbenzylamine (0.15 cm3, 1.0
mmol) and (C6F5)2PBr (0.445 g, 1.0 mmol). Yield: 0.35 g (70%).
1H NMR (CDCl3): δ (m, 2H, C6H4), 7. 19F (CDCl3): δ -130.51
3
(m, 4F, o-C6F5), -151.84 (t, J FF ) 21.2 Hz, 2F, p-C6F5),
3
-161.48 (m, 4F, m-C6F5). 31P (CDCl3): δ -56.5 (quintet, J PF
) 39.5 Hz). MS(EI) m/z: 499 (51%, M+); found for M+
499.05579. C21H12F10NP requires 499.05477.
[Cp *Rh Cl{(C6F 5)2P C6H4SMe-2}]BF 4, 7. [{RhCl(µ-Cl)(η5-
C5Me5)}2] (0.14 g, 0.22 mmol), 4 (0.28 g, 0.44 mol), and NaBF4
(0.11 g, 1 mmol) were treated as for the synthesis of [Cp*RhCl-
(dfppe)][BF4].8 Salt 5 was obtained as an orange oil. Yield: 0.40
g (79%). Repeated attempts at recrystallization failed to give
solid product, and elemental analysis could not be obtained.
Characterization is based on the NMR spectroscopic data and
comparison with similar compounds.8 1H NMR (CDCl3): δ 7.95
(m, 1H, C6H4), 7.73 (m, 1H, C6H4), 7.65 (m, 1H, C6H4), 7.54
(m, 1H, C6H4), 3.08 (s, 3H, SMe), 1.76 (d, J PH ) 4.7 Hz, 15H,
Cp*). 19F (CDCl3): δ -122.05 (m, 1F, o-C6F5), -126.75 (m, 1F,
o-C6F5), -127.47 (m, 1F, o-C6F5), -131.36 (m, 1F, o-C6F5),
1
1
δ 55.6 (dm, J RhP ) 143 Hz, 11b), 37.5 (dm, J RhP ) 146 Hz,
11a ). Anal. Calcd for C29H27BClF9PSRh‚0.33CH2Cl2: C, 44.76;
H, 3.54. Found: C, 44.85; H, 3.46.
[Cp *Rh Cl2{P Et2(C6F 5)}], 13b. PEt2(C6F5) (0.082 g, 0.32
mmol) in dichloromethane (20 cm3) was added to [Cp*RhCl-
(µ-Cl)]2 (0.10 g, 0.16 mmol) in methanol (10 cm3) and the
mixture stirred for 1 h under nitrogen. The volatiles were
removed under reduced pressure, and the red solid was washed
with hexane and recrystallized from hot toluene to give 0.13
g of 13b. Yield: 70%. Crystals for analysis and X-ray diffrac-
tion studies were grown from chloroform. 1H NMR (CDCl3):
4
-141.96 (t, 1F, 3J FF ) 19.8 Hz, p-C6F5), -144.39 (t, 1F, 3J FF
)
δ 2.38 (m, 4H, CH2), 1.39 (d, J PH 3.7 Hz, 15H, Cp*), 1.05 (dt,
3
3J PH 16.8 Hz, J HH 7.4 Hz, 6H, CH2CH3). 19F (CDCl3):
δ
19.8 Hz, p-C6F5), -153.69 (s, 0.8F, 10BF4-), -153.74 (s, 3.2F,
11BF4-), -154.74 (m, 1F, m-C6F5), -156.91 (m, 1F, m-C6F5),
-157.84 (m, 1F, m-C6F5), -160.31 (m, 1F, m-C6F5). 31P
3
3
-129.82 (t, J FF 16 Hz, 2F, o-C6F5), -153.25 (t, J FF ) 20 Hz,
1F, p-C6F5), -163.87 (m, 2F, m-C6F5). 31P (CDCl3): δ 33.9 (dt,
1J RhP ) 148 Hz, J PF ) 15.5 Hz). Anal. Calcd for C20H25Cl2F5-
3
1
(CDCl3): δ 30.2 (dm, J RhP ) 174 Hz).
[{η5,KP ,KS-C5Me4CH2C6F 4P (C6F 5)C6H4SMe}Rh Cl]BF 4, 8.
Salt 7 (0.4 g, 0.35 mmol) in chloroform (50 cm3) was treated
with proton sponge (0.08 g, 0.35 mmol). The mixture was
stirred for 30 min, and NaBF4 (0.10 g, 0.9 mol) and water (ca.
20 cm3) were added. The organic layer was separated and the
solvent removed under reduced pressure. The resulting orange
oil was washed with diethyl ether (2 × 50 cm3) and dried in
vacuo. Yield: 0.36 g (92%). Crystals for analysis and X-ray
PRh: C, 42.50; H, 4.46. Found: C, 42.46; H, 4.38.
[Cp *Rh Cl{P P h 2(C6F 5)}(CNP h )]BF 4, 14a . Salt 14a was
prepared as described for [(η5-C5Me4H)RhCl{PPh2(C6F5)}-
(CNC6H11)]BF423 from 13a , prepared in situ from [Cp*RhCl2]2
(0.200 g, 0.330 mmol) and PPh2(C6F5) (0.236 g, 0.670 mmol)
using phenylisonitrile (0.066 g, 0.640 mmol), and obtained as
an orange solid containing 0.5 molecule of dichloromethane.
1
Yield: 0.500 g, 88%. H NMR (CDCl3): δ 7.86 (2H, m, C6H5),
1
7.42 (11H, m, C6H5), 6.91 (2H, d, J ) 7.5 Hz, C6H5), 5.30 (s,
1H, CH2Cl2), 1.75 (15H, d, J PH ) 4.2 Hz, Cp*). 19F (CDCl3): δ
-124.15 (2F, m, o-F), -143.86 (1F, m, p-F), -153.81 (0.8F, s,
10BF4-), -153.86 (3.2F, s, 11BF4-), -157.24 (2F, m, m-F). 31P-
diffraction were grown from chloroform. H NMR (CDCl3): δ
8.08 (m, 1H, C6H4), 7.80 (m, 2H, C6H4), 7.71 (m, 1H, C6H4),
2
2
4.36 (dd, J PH ) 17.2, J HH ) 17.2, Hz, 1H, CH2), 3.03 (d, J HH
) 17.2 Hz, 1H, CH2), 2.60 (s, 3H, SMe), 2.17 (d, J PH ) 8.9 Hz,
3H, Me), 1.95 (d, J PH ) 3.5 Hz, 3H, Me), 1.65 (m, 3H, Me),
1.52 (s, 3H, Me). 19F (CDCl3): δ -119.73 (m, 1F), -126.32 (m,
1F), -132.89 (m, 1F), -134.35 (m, 1F), -142.43 (m, 1F),
1
{1H} (CDCl3): δ 22.6 (dm, J RhP ) 130 Hz). Anal. Calcd for
C
35H30BClF9NPRh‚0.5CH2Cl2: C, 49.68; H, 3.64; N, 1.63.
Found: C, 49.55; H, 3.57; N, 1.49.
3
-145.50 (t, 1F, J FF ) 19.8 Hz, p-C6F5), -151. 54 (m, 1F)
[Cp *Rh Cl{P P h 2(C6F 5)}(CNC6H11)]BF 4, 14b. Complex 13a
(0.110 g, 0.170 mmol) was treated with NaBF4 (0.022 g, 0.200
mmol) and cyclohexylisonitrile (0.022 g, 0.200 mmol) as
described for the preparation of [(η5-C5Me4H)RhCl{PPh2-
(C6F5)}(CNC6H11)]BF4.23 The product was obtained as a yellow
oil in virtually quantitative yield. Repeated recrystallization
failed to give solid product, and elemental analysis could not
be obtained. Characterization is based on the NMR spectro-
scopic data and comparison with similar compounds.23 1H NMR
(CDCl3): δ 7.77 (2H, m, C6H5), 7.47 (8H, m, C6H5), 4.17 (1H,
m, CNCH), 2.05 (2H, m, C6H11), 1.67 (15H, d, J PH ) 4.2 Hz,
Cp*), 1.61 (8H, m, C6H11). 19F (CDCl3): δ -123.79 (2F, br, o-F),
-144.21 (1F, br, p-F), -153.91 (0.8F, s, 10BF4-), -153.96 (3.2F,
s, 11BF4-), -157.38 (2F, br, m-F). 31P{1H} (CDCl3): δ 22.19 (dm,
1J RhP ) 129 Hz).
[Cp *Rh Cl{P Et2(C6F 5)}(CNC6H11)]BF 4, 14c. Complex 13b
(0.17 g, 0.3 mmol), cyclohexylisocyanide (0.036 g, 0.33 mmol),
and NaBF4 (0.11 g, 1 mmol) were treated as described for the
preparation of [(η5-C5Me4H)RhCl{PPh2(C6F5)}(CNC6H11)]BF4.23
The product was obtained as a yellow oil. Repeated recrystal-
lizations failed to give solid product, and elemental analysis
could not be obtained. Characterization is based on the NMR
-153.27 (s, 0.8F, 10BF4-), -153.33 (s, 3.2F, 11BF4-), -158.50
1
(m, 2F, m-C6F5). 31P (CDCl3): δ 58.6 (dm, J Rh-P ) 150 Hz).
Anal. Calcd for C29H21BClF13PRhS‚2.5CHCl3: C, 33.57; H,
2.10. Found: C, 33.47; H, 2.07.
(C6F 5)P h P X (X ) Cl or Br ), 9. A 1:3 ratio of PPh(C6F5)Cl,
9a , and PPh(C6F5)Br, 9b, was prepared from PhPCl2 and C6F5-
MgBr in diethyl ether as described.25 A ratio of 1:3 of 9a to 9b
was determined by 31P and 19F NMR spectroscopy. 1H
(CDCl3): 7.65 (2H, m), 7.40 (3H, m). 19F (CDCl3): -127.53 [2F,
m, Fortho 9b, 75%], -129.13, Fortho 9a , 25%], -147.39 (1F, m,
3
F
para), -160.36 (2F, m, Fmeta). 31P{1H} (CDCl3): 57.3 [t, J PF
)
3
49 Hz, 9a , 25%], 41.1 [t, J PF ) 49 Hz, 9b, 75%].
(C6F 5)P h P C6H4SMe-2, 10. Compound 10 was prepared as
for described for 4 from 2-bromothioanisole (0.50 g, 2.4 mmol)
and a 1:3 mixture of 9a and 9b (0.83 g, 2.4 mmol). The product
was purified by chromatography on a neutral deactivated
alumina using 2:1:1 hexane/toluene/diethyl ether as eluant.
1
Yield: 0.455 g (48%). H NMR (CDCl3): δ 7.53 (m, 5H), 7.35
(38) Blin, J .; Braunstein, P.; Fischer, J .; Kickelbick, G.; Knorr, M.;
Morise, X.; Wirth, T. J . Chem. Soc., Dalton Trans. 1999, 2159.

Intramolecular Dehydrofluorinative Coupling
Organometallics, Vol. 21, No. 26, 2002 5737
spectroscopic data and comparison with similar compounds.23
Yield: 0.18 g (83%). 1H NMR (CDCl3): δ 4.17 (1H, m, CNCH),
2.53 (4H, m, PCH2), 2.09 (2H, m, C6H11), 1.85 (2H, m, C6H11),
1.72 (15H, d, J PH ) 3.9 Hz, Cp*), 1.45 (6H, m, C6H11), 1.32
positions were added, and idealized positions and a riding
model with fixed thermal parameters (Uij ) 1.2Ueq for the atom
to which they are bonded (1.5 for CH3)) were used for
2
subsequent refinements. The function minimized was ∑[w(|Fo|
2
2
- |Fc| )] with reflection weights w-1 ) [σ2|Fo| + (g1P)2 + (g2P)]
3
3
(3H, dt, J PH ) 18.7 Hz, J HH ) 7.3 Hz, PCH2CH3), 1.16 (3H,
2
2
3
3
dt, J PH ) 17.4 Hz, J HH ) 7.6 Hz, PCH2CH3). 19F (CDCl3): δ
where P ) [max|Fo| + 2|Fc| ]/3. Additional material available
from the Cambridge Crystallographic Data Centre comprises
relevant tables of atomic coordinates, bond lengths and angles,
and thermal parameters (CCDC numbers: 2 190808, 8 155415,
13b 190807).
3
-128.86 (2F, m, o-C6F5), -144.86 (1F, t, J FF ) 19.5 Hz,
p-C6F5), -153.99 (0.8F, s, 10BF4-), -154.05 (3.2F, s, 11BF4-),
-157.20 (2F, m, m-C6F5). 31P (CDCl3): δ 34.9 (dt, J RhP ) 130
1
3
Hz, J PF ) 11 Hz).
X-r a y Cr ysta llogr a p h y. Crystals of 2, 8, and 13b were
obtained from chloroform. Crystal data are listed in Table 2.
Diffraction data were collected on a Bruker SMART diffrac-
tometer using the SAINT-NT39 software with graphite-mono-
chromated Mo KR radiation. A crystal was mounted on the
diffractometer at low temperature, ca. 120 K. Lorentz and
polarization corrections were applied. Empirical absorption
corrections were applied using SADABS.40 The structures were
solved using direct methods and refined with the program
package SHELXTL,41 and the non-hydrogen atoms were
refined with anisotropic thermal parameters. Hydrogen atom
Ack n ow led gm en t. We are grateful to Prof. R. P.
Hughes, Prof. D. S. Glueck, and Dr P. Bhattacharyya
for helpful discussions. We thank the E.P.S.R.C. for
support (to R.M.B.).
Su p p or tin g In for m a tion Ava ila ble: A listing of atomic
coordinates, anisotropic displacement parameters, and bond
distances and bond angles for 2‚2CHCl3, 8‚3CHCl3, and 13b.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM020612N
(39) SAINT-NT; Bruker AXS Inc.: Madison, WI, 1998.
(40) Sheldrick, G. M. SADABS; University of Go¨ttingen: Germany
1996.
(41) Sheldrick, G. M. SHELXTL; Bruker AXS Inc.: Madison, WI,
1998.