Synthesis and characterization of organopalladium complexes containing a fluoro ligand

Article abstract of DOI:10.1021/om9708440

The synthesis of organopalladium complexes containing a fluoro ligand, [(Ph₃P)₂Pd(F)R], is described. Two general synthetic strategies have been developed: (i) neutralization of hydroxo palladium dimers, [(Ph₃P)₂Pd₂(R)₂(μ-OH) ₂] (R = Me or Ph), with TREAT HF ([(HF)₃-NEt₃]) in the presence of PPh₃ and (ii) the ultrasound-promoted exchange between [(Ph₃P)₂Pd(I)R] and AgF in benzene. It is essential for the synthesis with TREAT HF that no excess of the HF source is used; otherwise, the corresponding bifluorides, [(Ph₃P)₂Pd-(FHF)R], are formed instead. Conducting the I/F exchange in the presence of 5-10% of the corresponding organic iodide, RI, is beneficial for purity of the desired fluoro complexes. All complexes 1-10 have been fully characterized by a variety of methods. The fluoro ligand in [(Ph₃P)₂Pd(F)R] is inert in anhydrous media of low polarity. However, in the presence of trace amounts of water, F ligand exchange is observed. No irreversible hydrolysis of the Pd-F bond takes place as [(Ph₃P)₂Pd(F)R] remains the only observable (NMR) species in the system. VT NMR studies of various [(Ph₃P)₂Pd(F)R] in CH2Cl2 saturated with water have been conducted, revealing a push/pull-type, ambiphilic mechanism of the H₂O-promoted F ligand-exchange process. The Pd-F bond cleavage likely involves nucleophilic attack of water on the metal center, concomitantly occurring with the formation of a hydrogen bond between the fluoro ligand and H₂O.

Full text of DOI:10.1021/om9708440

1774
Organometallics 1998, 17, 1774-1781
Syn th esis a n d Ch a r a cter iza tion of Or ga n op a lla d iu m
Com p lexes Con ta in in g a F lu or o Liga n d
Mark C. Pilon and Vladimir V. Grushin*,†
Department of Chemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada N2L 3C5
Received September 26, 1997
The synthesis of organopalladium complexes containing a fluoro ligand, [(Ph3P)2Pd(F)R],
is described. Two general synthetic strategies have been developed: (i) neutralization of
hydroxo palladium dimers, [(Ph3P)2Pd2(R)2(µ-OH)2] (R ) Me or Ph), with TREAT HF
([(HF)3‚NEt3]) in the presence of PPh3 and (ii) the ultrasound-promoted exchange between
[(Ph3P)2Pd(I)R] and AgF in benzene. It is essential for the synthesis with TREAT HF that
no excess of the HF source is used; otherwise, the corresponding bifluorides, [(Ph3P)2Pd-
(FHF)R], are formed instead. Conducting the I/F exchange in the presence of 5-10% of the
corresponding organic iodide, RI, is beneficial for purity of the desired fluoro complexes.
All complexes 1-10 have been fully characterized by a variety of methods. The fluoro ligand
in [(Ph3P)2Pd(F)R] is inert in anhydrous media of low polarity. However, in the presence of
trace amounts of water, F ligand exchange is observed. No irreversible hydrolysis of the
Pd-F bond takes place as [(Ph3P)2Pd(F)R] remains the only observable (NMR) species in
the system. VT NMR studies of various [(Ph3P)2Pd(F)R] in CH2Cl2 saturated with water
have been conducted, revealing a push/pull-type, “ambiphilic” mechanism of the H2O-
promoted F ligand-exchange process. The Pd-F bond cleavage likely involves nucleophilic
attack of water on the metal center, concomitantly occurring with the formation of a hydrogen
bond between the fluoro ligand and H2O.
In tr od u ction
basis of elemental analysis data, with no evidence for
the presence of a Pd-F bond. A cationic Pd(II) fluoro
complex [(Et3P)3PdF]+ has been characterized by 19F
NMR in solution but never isolated.10 In light of the
recent studies by Mason and Verkade,11 one might
expect the cation, [(Et3P)3PdF]+, to be very unstable,
readily decomposing to a mixture of Pd(0) and P(V)
compounds.
Organometallic complexes of palladium containing a
fluoro ligand are of special interest due to their potential
role in organofluorine chemistry. In this paper, we
report the synthesis and characterization of a series of
novel organopalladium fluoro complexes of the type
[(Ph3P)2Pd(R)F], where R ) Ar or Me. Part of this work
has been recently published as a preliminary com-
munication.12 Two synthetic techniques will be de-
scribed: (i) neutralization of organopalladium hydrox-
ides with TREAT HF, a 3:1 complex of HF with
Late transition metal complexes containing a fluoro
ligand are of considerable interest in modern research
due to their relevance to contemporary concepts of
bonding in coordination chemistry, C-F bond activation
and formation, and catalysis.1-4 The latter makes fluoro
complexes of the platinum group metals especially
attractive. However, surprisingly little is known about
fluoro palladium compounds, despite the fact that
palladium is one of the most important catalytic metals
whose complexes are capable of promoting a wide
variety of reactions,5 including important industrial
processes.6 Although some inorganic solid-state pal-
ladium fluorides have been synthesized,7 no reports
have appeared in the literature describing the isolation
and reliable characterization of molecular palladium
fluorides. Two compounds have been formulated as
[(Ph3P)4Pd2(µ-F)2]F2 and [(Ph3P)2Pd(H)F]9 only on the
8
(7) (a) For examples of structurally characterized solid-state pal-
ladium fluorides, see: [PdF6]2- 7b KPdF3,7c PdF4,7d PdF2,7e and M2PdF4
,
† Present address: E. I. Du Pont de Nemours and Company, Central
Research and Development, Experimental Station E328/306, Wilm-
ington, DE 19880.
(1) (a) Doherty, N. M.; Hoffman, N. W. Chem. Rev. 1991, 91, 553.
(b) Witt, M.; Roesky, H. W. Prog. Inorg. Chem. 1992, 40, 353.
(2) Holloway, J . H.; Hope, E. G. J . Fluorine Chem. 1996, 76, 209.
(3) Kiplinger, J . L.; Richmond, T. G.; Osterberg, C. E. Chem. Rev.
1994, 94, 373.
(4) (a) Hudlicky, M. J . Fluorine Chem. 1989, 44, 345. (b) For
homogeneous, catalytic C-F bond activation, see: Aizenberg, M.;
Milstein, D. Science 1994, 265, 359; J . Am. Chem. Soc. 1995, 117, 8674.
(5) For a recent monograph, see: Tsuji, J . Palladium Reagents and
Catalysis: Innovations in Organic Synthesis; Wiley: Chichester, 1995.
(6) (a) Parshall, G. W.; Ittel, S. D. Homogeneous Catalysis. The
Applications and Chemistry of Catalysis by Soluble Transition Metal
Complexes; Wiley: New York, 1992. (b) Wiessermel, K.; Arpe, H.-J .
Industrial Organic Chemistry; VCH: New York, 1993.
(M ) Na and K).7f (b) Leary, K.; Templeton, D. H.; Zalkin, A.; Bartlett,
N. Inorg Chem. 1973, 12, 1726. (c) Alter, E. Z. Anorg. Allg. Chem. 1974,
408, 115. (d) Wright, A. F.; Fender, B. E. F.; Bartlett, N.; Leary, K.
Inorg. Chem. 1978, 17, 748. (e) Tressaud, A.; Soubeyroux, J . L.;
Touhara, H.; Demazeau, G.; Langlais, F. Mater. Res. Bull. 1981, 16,
207. (f) Bachmann, B.; Mueller, B. G. Z. Anorg. Allg. Chem. 1991, 597,
9.
(8) Peacock, R. D.; Kemmitt, R. D. W.; Stocks, J . J . Chem. Soc. A
1971, 846.
(9) Doyle, G. J . Organomet. Chem. 1982, 224, 355.
(10) (a) Dixon, K. R.; McFarland, J . J . J . Chem. Soc., Chem.
Commun. 1972, 1274. (b) Cairns, M. A.; Dixon, K. R.; McFarland, J .
J . J . Chem. Soc., Dalton Trans. 1975, 1159.
(11) Mason, M. R.; Verkade, J . G. Organometallics 1990, 9, 864;
1992, 11, 2212.
(12) Fraser, S. L.; Antipin, M. Yu.; Khroustalyov, V. N.; Grushin,
V. V. J . Am. Chem. Soc. 1997, 119, 4769.
S0276-7333(97)00844-3 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 03/31/1998

Synthesis of Organopalladium Complexes
Organometallics, Vol. 17, No. 9, 1998 1775
Ta ble 1. Isola ted Yield s a n d An a lytica l Da ta for th e Com p lexes [(P h 3P )2P d (R)(X)] (X ) F or HF 2), 1-10
analysis, calcd (found)
complex
R
X
fluorinating agent
yield, %
% C
% H
1
2
3
4
5
6
7
8
C6H5
CH3
C6H5
CH3
4-CH3C6H4
4-CH3OC6H4
1-C10H7
4-ClC6H4
4-CF3C6H4
4-O2NC6H4
F
F
HF2
HF2
F
F
F
F
F
TREAT HF or AgF
TREAT HF or AgF
TREAT HF
TREAT HF
AgF
AgF
AgF
AgF
AgF
90-98
60-85
95-99
85-90
71-92
80-96
92-98
71-87
80-86
86-90
69.4 (69.5)
66.8 (67.1)
67.5 (67.6)
64.9 (64.7)
69.7 (69.5)
68.2 (68.0)
71.1 (71.0)
66.2 (66.1)
62.4 (62.4)
65.3 (65.1)
4.9 (4.9)
5.0 (5.1)
4.9 (4.9)
5.0 (4.9)
5.0 (5.1)
4.9 (5.1)
4.8 (4.9)
4.5 (4.7)
4.2 (4.5)
4.4 (4.6)
9a
10
F
AgF
a
Complex 9 was isolated as a 2:1 dichloromethane adduct, [(Ph3P)2Pd(4-CF3C6H4)(F)]‚1/2CH2Cl2.
triethylamine, and (ii) ultrasound-promoted I/F ex-
change between iodo organopalladium complexes and
silver(I) fluoride. Both methods seem to be general and,
therefore, might be applicable to the preparation of
otherwise unobtainable fluoro complexes of other tran-
sition metals.
procedure developed for [(Ph3P)2Pd2(Ph)2(µ-OH)2],14a
most likely due to the σ-aryl/phosphine aryl exchange16
occurring in the course of the reaction between [(Ph3P)2-
PdCl2], p-iodotoluene, and alkali. On the other hand,
it is thought that our neutralization method employing
TREAT HF could be successfully used for the prepara-
tion of fluoro complexes of other transition metals from
various readily accessible17-19 hydroxo derivatives.
Ult r a sou n d -P r om ot ed E xch a n ge b et w een AgF
a n d Or ga n op a lla d iu m Iod id es. The other synthetic
method for the preparation of organopalladium fluorides
is based upon the ultrasound-promoted halide exchange
between readily available organopalladium iodides,
[(Ph3P)2Pd(Ar)(I)],20 and silver fluoride in benzene (eq
3). All fluoro palladium complexes obtained by both
Resu lts a n d Discu ssion
Neu t r a liza t ion of P a lla d iu m H yd r oxo Com -
p lexes w ith TREAT HF . In a number of cases, HF
has been used for the preparation of fluoro complexes
of Fe, Mo, Tc, Ru, W, Re, Ir, and Pt.1 An efficient
substitute for anhydrous hydrogen fluoride, “TREAT
HF” (Et3N‚3HF), is a new, versatile fluorinating agent
which has already been widely used in organic syn-
thesis13a but only recently applied in organometallic
chemistry.12,13b We found that the reaction between
TREAT HF, a hydroxo palladium dimer, [(Ph3P)2Pd2-
(R)2(µ-OH)2], where R ) Ph14a or Me,14b and PPh3 in a
2:3:6 molar ratio furnished the corresponding fluorides,
trans-[(Ph3P)2Pd(R)(F)] (R ) Ph, 1, and Me, 2), in high
yield (eq 1). Each molecule of Et3N‚3HF “neutralizes”
[(Ph3P)2Pd(Ar)I] +
AgF ultrasound8 [(Ph3P)2Pd(Ar)F] + AgI (3)
benzene
1, Ar ) Ph
5, Ar ) 4-CH3C6H4
6, Ar ) 4-CH3OC6H4
7, Ar ) 1-C10H7
8, Ar ) 4-ClC6H4
9, Ar ) 4-CF3C6H4
10, Ar ) 4-NO2C6H4
3[(Ph3P)2Pd2(R)2(µ-OH)2] + 2[Et3N(HF)3] +
6PPh3 benzene8 6[(Ph3P)2Pd(R)(F)] + 2Et3N + 6H2O
1, R ) Ph
2, R ) Me
techniques, their yields, and analytical data are sum-
marized in Table 1.
(1)
Silver fluoride has been used for the preparation of
various fluoro complexes.1 These reactions are normally
conducted in polar solvents, such as methanol, aceto-
nitrile, and acetone, in which AgF is somewhat soluble.
three hydroxo ligands on the metal. Any excess of
TREAT HF must be avoided for the synthesis of 1 and
2 because, like their platinum counterparts15a,b and
some other transition metal fluorides,13b,15c,d the desired
fluorides are prone to forming stable adducts with HF,
trans-[(Ph3P)2Pd(R)(HF2)] (R ) Ph, 3, and Me, 4; eq 2).
(13) (a) McClinton, M. A. Aldrichim. Acta 1995, 28, 31 and refer-
ences cited therein. (b) It was recently reported that the reaction
between TREAT HF and cis-[(dmpe)2RuH2] resulted in the formation
of trans-[(dmpe)2Ru(H)(FHF)] as the major product, see: Whittlesey,
M. K.; Perutz, R. N.; Greener, B.; Moore, M. H. J . Chem. Soc., Chem.
Commun. 1997, 187.
(14) (a) Grushin, V. V.; Alper, H. Organometallics 1993, 12, 1890.
(b) Grushin, V. V.; Bensimon, C.; Alper, H. Organometallics 1995, 14,
3259.
(15) (a) Coulson, D. R. J . Am. Chem. Soc. 1976, 98, 3111. (b)
Hintermann, S.; Pregosin, P. S.; Ru¨egger, H.; Clark, H. C. J . Orga-
nomet. Chem. 1992, 435, 225. (c) Roesky, H. W.; Sotoodeh, M.; Xu, Y.
M.; Schrumpf, F.; Noltemeyer, M. Z. Anorg. Allg. Chem. 1990, 580,
131. (d) Murphy, V. J .; Hascall, T.; Chen, J . Y.; Parkin, G. J . Am. Chem.
Soc. 1996, 118, 7428.
(16) (a) Kong, K.-C.; Cheng, C.-H. J . Am. Chem. Soc. 1991, 113,
6131. (b) Goodson, F. E.; Wallow, T. I.; Novak, B. M. J . Am. Chem.
Soc. 1997, 119, 12441 and references cited therein.
[(Ph3P)2Pd2(R)2(µ-OH)2] +
2PPh3 TREAT HF (excess)8 2[(Ph3P)2Pd(R)(FHF)] (2)
-2H2O
3, R ) Ph
4, R ) Me
Reactions 1 and 2 as well as the subsequent isolation
of the products were conducted in air, affording com-
plexes 1-4 as white or pale cream-yellow, well-shaped
crystals. The “neutralization” method is simple and
efficient. Its major limitation, however, stems from the
fact that hydroxo palladium dimers of the type [(Ph3P)2-
Pd2(Ar)2(µ-OH)2] are difficult to synthesize when Ar )
σ-aryls other than phenyl. For instance, pure [(Ph3P)2-
Pd2(4-CH3C6H4)2(µ-OH)2] cannot be obtained by the
(17) Bryndza, H. E.; Tam, W. Chem. Rev. 1988, 88, 1163.
(18) Gilje, J . W.; Roesky, H. W. Chem. Rev. 1994, 94, 895.
(19) Bergman, R. G. Polyhedron 1995, 14, 3227.
(20) (a) Fitton, P.; Rick, E. A. J . Organomet. Chem. 1971, 28, 287.
(b) Garrou, P. E.; Heck, R. F. J . Am. Chem. Soc. 1976, 98, 4115.

1776 Organometallics, Vol. 17, No. 9, 1998
Pilon and Grushin
Sch em e 1
Using these solvents for the synthesis of the palladium
fluoro complexes, 1, 2, 5-10, would be futile as the
target products are insoluble in acetonitrile while being
reactive toward acetone and, especially, methanol (see
below). Simply stirring the iodo palladium complex,
[(Ph3P)2Pd(Ph)(I)], with AgF in benzene resulted in poor
conversions and yields. Under sonication, however, this
reaction smoothly occurred, furnishing the desired
fluoride in 80-98% isolated yield at 100% conversion.
We believe that this method might be successfully
extended to the preparation of a large variety of transi-
tion metal fluoro complexes from their much more
readily available iodo derivatives. For this reason, a
very detailed description of the synthetic procedure
developed for the F/I exchange under sonication is
presented in the Experimental Section.
When duplicating the I/F exchange reactions de-
scribed in this paper, one should not rely completely on
the reaction times specified in the Experimental Section
but rather frequently monitor the process (e.g., by 31P
NMR).24 In some cases, the Pd fluorides isolated from
the I/F exchange experiments were yellow or even
brown, although complexes of the type [(Ph3P)2Pd(R)F]
are white in nature. However, no side products were
detected by 31P NMR analysis of the reaction mixtures,
and all fluoro complexes isolated were found to be
spectroscopically pure, regardless of their color. The
high yields (Table 1) of the fluoro complexes also
suggested that the side reactions were minor, producing
just trace amounts of deeply colored impurities. Inter-
estingly, once quantitative conversion was achieved,
filtration of the reaction suspension would sometimes
produce virtually colorless, clear solutions which dark-
ened upon isolation of the product. It was also noticed
that while remaining spectroscopically pure, the prod-
ucts became deeper in color upon prolonged exposure
to light. At the same time, the reaction between a
bromo complex, [(Ph3P)2Pd(Ph)(Br)], and AgF always
gave white products, albeit the conversion never reached
100% (see above).
We found that the formation of the colored impurities
can be suppressed by conducting the I/F exchange in
the presence of small amounts of the corresponding
iodoarene. For instance, the reaction between [(Ph3P)2-
Pd(4-CH3C6H4)(I)] and AgF was conducted several
times, always affording spectroscopically pure 5 in high
yield. However, the exchange in the absence of
4-CH3C6H4I gave the desired product as a brownish-
grey solid, whereas white crystals of 5 were isolated
from the exchange carried out in the presence of 5-10
Reaction 3 is heterogeneous in nature. We have
noticed that even under similar conditions the reaction
time may vary in a broad range, sometimes from 1 to
10 h, depending on the size of the AgF granules used
as well as the stirring and sonication efficiency. When
a bromo complex, [(Ph3P)2Pd(Ph)(Br)], was used for the
synthesis instead of its iodo analogue, the reaction was
sluggish, taking over 1 day for just ca. 70-80% conver-
sion. This observation suggests that the mechanism of
the exchange likely involves the interface formation of
a bimetallic complex, e.g., [(Ph3P)2Pd(Ph)(µ-I)(µ-F)Ag],
which eliminated AgI to give the palladium fluoride. As
the ∆H° values for crystalline AgF and AgI are -48.5
f
and -14.91 kcal/mol, respectively,21 the driving force
for the PdI/AgF exchange might be the superior stability
of the palladium fluoride product. Indeed, it was
recently established22 that for anhydrous media of low
polarity (CH2Cl2 and CHCl3), the affinity of the metal
center in [(Ph3P)2Pd(Ph)(X)] for various halogens, X,
decreases in the order F > Cl > Br > I. Similar
observations were previously made for a series of Rh(I)
complexes.23
(23) Araghizadeh, F.; Branan, D. M.; Hoffman, N. W.; J ones, J . H.;
McElroy, E. A.; Miller, N. C.; Ramage, D. L.; Salazar, A. B.; Young, S.
H. Inorg. Chem. 1988, 27, 3752. Branan, D. M.; Hoffman N. W.;
McElroy, E. A; Miller, N. C.; Ramage, D. L.; Schott, A. F.; Young, S.
H. Inorg Chem. 1987, 26, 2915.
(24) (a) Following the I/F exchange reactions by 31P NMR is
convenient because the signals of the starting iodo complexes are 3-5
ppm downfield from those of the corresponding fluorides. It is worth
noting that because the I/F exchange reactions were run in the
presence of small amounts of water,24b the 31P NMR spectra of the
reaction mixtures exhibited slightly broadened singlet resonances for
the fluoro complexes (see text). (b) Silver(I) fluoride originating from
aqueous solutions always contains some amounts of water which is
virtually impossible to remove, see: Horn, E.; Snow, M. R. Aust. J .
Chem. 1980, 33, 2369.
(21) CRC Handbook of Chemistry and Physics, 57th ed.; Weast, R.
C., Ed.; CRC Press: Cleveland, 1976; p D-75.
(22) (a) Grushin, V. V. Angew.Chem. 1998, in press. (b) Flemming,
J . P.; Pilon, M. C.; Borbulevitch, O. Ya.; Antipin, M. Yu.; Grushin, V.
V. Inorg Chim. Acta 1998, in press.

Synthesis of Organopalladium Complexes
Organometallics, Vol. 17, No. 9, 1998 1777
Ta ble 2. 31P a n d 19F NMR Da ta for
Or ga n op a lla d iu m F lu or o Com p lexes,
tr a n s-[(P h 3P )2P d (F )(R)], in Dich lor om eth a n e
mol % of p-iodotoluene. Scheme 1 readily accounts for
the beneficial effect of iodoarenes. In the course of the
I/F exchange, a small amount of the palladium(II)
complexes possibly decomposed to give Pd(0), e.g., via
the fluoride-induced intramolecular redox process,
[Pd(II)-P(III)/Pd(0)-P(V)].11 The resulting coordina-
tively unsaturated zerovalent complexes, [(Ph3P)nPd]
(n ) 1 or 2), are known to be unstable, disproportion-
ating rapidly to Pd metal, [(Ph3P)3Pd], and [(Ph3P)4-
Pd].14b The latter is completely dissociated in solution
to [(Ph3P)3Pd] and free triphenylphosphine,25 which
easily forms soluble complexes with silver halides.26 The
Pd(0) side products and iodotriphenylphosphinesilver
species contaminated the fluoro palladium complexes,
subsequently staining them upon air- and light-induced
decomposition. In the presence of ArI, however, the C-I
bond would oxidatively add to [(Ph3P)nPd] (n ) 1 or 2)
prior to its disproportionation,14b thus terminating the
formation of free PPh3 and its soluble silver complexes.
The oxidative addition of Ar-I to the Pd(0) should
produce the starting σ-aryl iodo Pd complex, which
would eventually be converted, in situ, to the desired
Pd fluoride because an excess of AgF was always used
for the synthesis.
31P NMR,
19F NMR,
J F-P,
complex
δa
δb
Hz
[(Ph3P)2Pd(C6H5)F], 1
[(Ph3P)2Pd(CH3)F], 2
19.5
24.5
18.9
19.7
19.7
19.2
19.7
19.3
-274
-268
-274
-276
-275
-279
13.3
12.5
12.0
11.8
12.5
13.0
[(Ph3P)2Pd(4-C6H4CH3)F], 5
[(Ph3P)2Pd(4-C6H4OCH3)F], 6
[(Ph3P)2Pd(l-C10H7)F], 7
[(Ph3P)2Pd(4-C6H4Cl)F], 8
[(Ph3P)2Pd(4-C6H4CF3)F], 9
[(Ph3P)2Pd(4-C6H4NO2)F], 10
-280; -63c 10.8
-283
10.4
a
b
External standard: 85% H3PO4. External standard: CFCl3.
c The singlet resonance at -63 ppm is due to the CF3 group.
In the presence of trace amounts of water, however,
the 31P and 19F NMR signals from 1 appear as broad-
ened singlets with similar chemical shifts and ∆ν1/2
)
5-20 (31P) and 50-150 Hz (19F). The loss of P-F
coupling was indicative of exchange processes occurring
in moist solutions of 1. Processes involving Pd-F
ionization (eq 4) and/or Pd-F‚‚‚HOH hydrogen bond
formation (eq 5) were conceivable.
H2O
[(Ph3P)2Pd(Ph)F] y z [(Ph3P)2Pd(Ph)]+ + F- (4)
Ch a r a ct er iza t ion of F lu or o P a lla d iu m Com -
p lexes. Complexes 1-10 are air-stable compounds. If
pure, they can be stored in air at room temperature for
weeks and even a few months without decomposition.
All palladium fluorides are easily soluble in dichlo-
romethane and chloroform, moderately soluble in ben-
zene, but insoluble in alkanes, acetonitrile, acetone, and
methanol. However, adding MeOH to a benzene solu-
tion of 1 does not result in precipitation of the complex
but rather its slow (hours at room temperature) decom-
position to Pd(0), Ph3PO, and other products.
[(Ph3P)2Pd(Ph)F] + H2O h [(Ph3P)2Pd(Ph)F---HOH]
(5)
Thermodynamic considerations predict that as the
sample is being cooled the formation of 1 should be
favored by equilibrium 4, which will shift to the left,
but disfavored by equilibrium 5 due to its shift to the
right. The room-temperature 31P NMR spectrum of 1
in CH2Cl2 (stock bottle; water content <0.1%) exhibited
a singlet at 19.7 ppm with ∆ν1/2 ) 7.5 Hz (<J PF ) 13.3
Hz). Upon slowly cooling the sample to +5 °C, this
singlet resonance resolved into a doublet identical with
that observed for anhydrous solutions of 1 at 20 °C. At
coalescence (ca. +10 °C), ∆Gq for Pd-F ionization was
calculated29 to be 14.6 kcal/mol. The VT NMR data
obtained was indicative of Pd-F ionization (eq 4), i.e.,
in the presence of small amounts of H2O, the fluoro
ligand in complex 1, at ambient temperature, became
labile on the NMR time scale. Evidence has been
reported for facile ionization of the palladium-halogen
bond in closely related complexes [L2Pd(X)Ar] (L )
tertiary phosphine, X ) halogen) of both trans16b,22 and
cis30 geometry, under mild conditions.
Equilibrium 5 alone fails to account for the VT NMR
behavior observed. Clearly, the formation of 1 via loss
of water from [(Ph3P)2Pd(Ph)(F‚‚‚HOH)] would be fa-
vored at higher rather than lower temperatures. By no
means does this imply, however, that no hydrogen bond
formation between 1 and water takes place. Moreover,
the Pd-F‚‚‚HOH hydrogen bond likely plays an impor-
tant role in the Pd-F ionization process (see below).
Because no other resonances were observed in the
low-temperature 31P NMR spectrum of 1, all the equi-
The nature of the Pd-F bond in 1-10 is an important
issue from the perspective of potential use of such
complexes in synthesis and catalysis. Since the fluoride
anion is the hardest base known (orbital electronega-
tivity in water is -12.18 eV) while Pd2+ is a soft acid,
the interaction between them is expected to be neither
charge- nor orbital-controlled.27 Although one might
anticipate a Pd-F bond to be rather weak and easily
ionized, this is not true for organopalladium fluorides
1-10. The X-ray structure of almost ideally square-
planar 1 suggests that the Pd-F bond (2.085(3) Å) is
covalent.12 The 19F and 31P NMR spectral characteris-
tics for the fluoro complexes are summarized in Table
2. In anhydrous28 solvents of low polarity, such as
benzene, chloroform, and dichloromethane, all ligands
on the Pd atom in 1 are inert on the NMR time scale.
For solutions of 1 in dry CD2Cl2, a doublet at 19.5 ppm
and a triplet at -274 ppm with the same coupling
constant (J P-F ) 13.3 Hz) are observed in the 31P and
19F NMR spectra, respectively.12
(25) Kurran, W.; Musco, A. Inorg. Chim. Acta 1975, 12, 187. Mann,
B. E.; Musco, A. J . Chem. Soc., Dalton Trans. 1975, 1673.
(26) Lancashire, R. J . In Comprehensive Coordination Chemistry;
Wilkinson, G., Ed.; Pergamon Press: Oxford, 1987; Vol. 5, p 775.
(27) Klopman, G. In Chemical Reactivity and Reaction Paths;
Klopman, G., Ed.; J ohn Wiley and Sons: New York, 1974; p 55.
(28) Samples for the NMR studies of complexes 1-10 were prepared
by vacuum transfer of the dry solvent to a solid complex placed in a
standard 5-mm NMR tube. The tube was then filled with nitrogen and
sealed. The prepurified solvent was stirred with P2O5 under nitrogen
for at least 24 h prior to use.
(29) (a) k ) πJ /x2 ) 30 s-1, where J ) coupling constant in hertz;
∆Gq ) RT{ln(kB/h) - ln(k/T)} ) 14.6 kcal/mol, where kB is Boltzmann’s
constant, h is Planck’s constant, and R is the universal gas constant.29b
(b) Harris, R. K. Nuclear Magnetic Resonance Spectroscopy: A Phys-
icochemical View; Longman Scientific & Technical: Harlow, 1986.
(30) Portnoy, M.; Ben-David, Y.; Rousso, I.; Milstein, D. Organo-
metallics 1994, 13, 3465.

1778 Organometallics, Vol. 17, No. 9, 1998
Pilon and Grushin
Sch em e 2
Ta ble 3. Tem p er a tu r e of Coa lescen ce a n d ∆Gq
Va lu es Obta in ed fr om VT 31P NMR Stu d ies of
Solu tion s of tr a n s-[(P h 3P )2P d (F )(R)] (0.0185 m m ol)
in CH2Cl2 (0.5 m L) Con ta in in g Wa ter (0.037 m m ol)
NMR spectra of these samples exhibited singlet reso-
nances which resolved into doublets upon cooling. As
seen from Table 3, there was no correlation between the
electronic effects of the substituents on the benzene ring
and the temperature of coalescence. Both strong elec-
tron-withdrawing and electron-releasing substituents
facilitated the exchange, whereas the slowest ionization
was observed for 7 and 8 containing relatively “neutral”
1-naphthyl and 4-chlorophenyl ligands.36
The lack of correlation may be rationalized in terms
of both electrophilic and nucleophilic attack of H2O on
the fluoro complex. Water may cause the ionization of
the Pd-F bond by coordinating to the metal center (A;
nucleophilic cleavage)37 or by forming a hydrogen bond
with the F ligand (B; electrophilic cleavage).38-40 It is
also conceivable that the Pd-F bond ionizes via both
nucleophilic and electrophilic paths concomitantly, as
shown in structures C and D (“ambiphilic” or push/pull-
type mechanisms).
temp of
coalescence, K
∆Gq,
kcal/mol
complex
[(Ph3P)2Pd(C6H5)F], 1
[(Ph3P)2Pd(CH3)F], 2
253
233
253
253
273
288
248
258
13.0
12.0
13.1
13.1
14.1
14.9
12.9
13.4
[(Ph3P)2Pd(4-C6H4CH3)F], 5
[(Ph3P)2Pd(4-C6H4OCH3)F], 6
[(Ph3P)2Pd(1-C10H7)F], 7
[(Ph3P)2Pd(4-C6H4Cl)F], 8
[(Ph3P)2Pd(4-C6H4CF3)F], 9
[(Ph3P)2Pd(4-C6H4NO2)F], 10
libria between the fluoro complexes and products of
Pd-F ionization were obviously shifted almost entirely
toward the fluoro complex. This is consistent with the
fact that the synthesis, isolation, and recrystallization31
of the fluoro complexes were successfully carried out
with solvents which had not been dried. The spectral
parameters, reactivity, and color of 1 were different from
those of the cationic complex, [(Ph3P)2Pd(Ph)]+,32 which
would form upon complete loss of F- from 1. The
hydrolysis of 1 (Scheme 2) is the reverse of its formation
from the Pd hydroxo dimer and HF in the form of
TREAT HF (compare eq 1 and Scheme 2).33,34 Obvi-
ously, in the presence of water, the Pd-F bond is not
inert, albeit certainly favored by thermodynamics.
In an attempt to reveal mechanistic features of the
water-induced Pd-F ionization, we undertook VT NMR
studies of various arylpalladium fluorides in wet CH2Cl2
(Table 3). For each of the samples studied ([(Ph3P)2-
Pd(R)F] ) 3.7 × 10-2 mol/L) the molar ratio of water to
the Pd fluoride was 2:1.35 All room-temperature 31P
Depending on the nature of group X (structures
A-D), the Pdδ+-Fδ- bond is polarized to a different
extent. Electron-withdrawing substituents on the ring
(36) The lack of correlation cannot be accounted for by impurities
in the fluoro complexes used for the VT NMR studies. Two recrystal-
lizations of 7 from dichloromethane-hexane did not affect the tem-
perature of coalescence. No difference in the VT NMR behavior was
observed for similarly prepared wet dichloromethane solutions of 1
originating from the TREAT HF and AgF reactions.
(37) Alkaline hydrolysis of [(Ph3P)2Pd(Ph)I] to [(Ph3P)2Pd2(Ph)2(µ-
OH)2] in the presence of 18-crown-6 likely involves nucleophilic attack
of OH- on the metal center, see: Grushin, V. V.; Alper, H. J . Am. Chem.
Soc. 1995, 117, 4305. Adding solid KOH to a dichloromethane solution
of 1 resulted, within hours, in the formation of PPh3 and the hydroxo
palladium dimer,14a which were identified by 31P NMR.
(38) For examples of hydrogen bonds to fluoro ligands in transition
metal complexes, see: Richmond, T. G. Coord. Chem. Rev. 1990, 105,
221.
(39) (a) Veltheer, J . E.; Burger, P.; Bergman, R. G. J . Am. Chem.
Soc. 1995, 117, 12478. (b) Mechanism B may govern ionization of the
Ir-F bond in the 18e complex, [Cp*Ir(PMe3)(Ph)F], whose hydrolysis
is “likely aided by hydrogen bonding”,39a whereas direct coordination
of H2O to the electronically saturated Ir center is unlikely. The Pd
fluorides are 16e complexes which may undergo facile ligand exchange
via the associative mechanism. In aqueous THF, [Cp*Ir(PMe3)(Ph)F]
exists in equilibrium with a species formulated as [Cp*Ir(PMe3)(Ph)-
(H2O)]+[F‚xH2O]-.39a Depending on the amount of water added, the
equilibrium can be shifted toward the covalent fluoride or the cationic
aqua complex. Nonetheless, the fluoro ligand on the Ir atom remains
inert on the NMR time scale, regardless of the position of the
equilibrium. In contrast, the Pd-F bond is labile on the NMR time
scale (at room temperature) when complexes of the type [(Ph3P)2Pd-
(R)F] are dissolved in solvents containing even small amounts of H2O.
(40) Intermediate B, [(Ph3P)2Pd(R)(F‚‚‚HOH)], contains the already
“hydrated” fluoride as a ligand which is an incomparably better leaving
group than the F-. There is much similarity between this intermediate
and bifluoride complexes 3 and 4, in which the FHF ligand is labile
under rigorously dry conditions. The 1H NMR spectra of 3 and 4 are
almost indistinguishable from those of their fluoro counterparts, 1 and
2, respectively, except for the presence of broad downfield resonances
at ca. 12.5 ppm arising from the FHF ligand. At room temperature,
19F NMR signals of 3 and 4 were too broad to be observed and only
singlet resonances were found in the 31P NMR spectra of 3 and 4 in
dry dichloromethane (see Experimental Section), obviously due to
fluorine exchange processes. Upon cooling a dichloromethane solution
of 4 to -85 °C, the 31P NMR singlet resonance transformed to a broad,
poorly resolved doublet (δ ) 27 ppm; J P-F ) 8.3 Hz).
(31) The fluoro complexes are convenient to recrystallize by adding
pentane or hexane to their concentrated solutions in benzene or,
preferentially, dichloromethane. Precipitating the complexes with ether
instead of pentane or hexane normally results in substantial losses,
especially for compound 9 which is slightly soluble in ether, perhaps
due to the lipophilic CF3 group. Complexes 1-10 can also be success-
fully recrystallized by adding toluene to their concentrated dichlo-
romethane solution, followed by removal of the CH2Cl2 by rotary
evaporation (15-30 min at ambient temperature) and keeping the
resulting solution at ca. -15 to -20 °C overnight.
(32) Amatore, C.; Carre´, E.; J utand, A.; M’Barki, M. A.; Meyer, G.
Organometallics 1995, 14, 5605.
(33) The hydroxo palladium complexes are obviously more basic than
triethylamine since the reaction between [(Ph3P)2Pd2(R)2(µ-OH)2] (3
equiv) and [(HF)3‚NEt3] (2 equiv) in the presence of PPh3 occurs
quantitatively, resulting in the formation of the corresponding fluoro
complex and free Et3N.
(34) (a) Although it has been established34b that the equilibrium
between [(Ph3P)2Pd(R)(OH)] and [(Ph3P)2Pd2(R)2(µ-OH)2] (R ) Ph or
Me) is shifted almost entirely toward the dimer, the palladium fluoride
remains the only thermodynamically favored species when dissolved
in dichloromethane saturated with water (Scheme 2). (b) Grushin, V.
V.; Alper, H. Organometallics 1996, 15, 5242.
(35) (a) All samples were made up by dissolving 0.0185 mmol of each
fluoro complex in 0.5 mL of CH2Cl2 saturated with water (0.198% by
weight at 20 °C).40b (b) Riddick, J . A.; Bunger, W. B.; Sakano, T. K.
Organic Solvents. Physical Properties and Methods of Purification, 4th
ed.; Wiley: New York, 1986; p 490-491.

Synthesis of Organopalladium Complexes
Organometallics, Vol. 17, No. 9, 1998 1779
tion in organomercury compounds is orders of magni-
tude faster in the presence of nucleophiles.45 Although
the reaction between diphenylmercury and sulfuric acid
is sluggish, the C-Hg bond is cleaved very rapidly when
I- is added (eq 7).
Exp er im en ta l Section
Gen er a l Con sid er a tion s. A Varian VXR-200 NMR spec-
trometer was used for measuring 1H, 19F, and 31P NMR
spectra. Elemental analyses were carried out by M-H-W
Laboratories (Phoenix, AZ). Silver fluoride, TREAT HF, and
other chemicals were purchased from Aldrich Chemical Co.
and used as received. The organopalladium hydroxo com-
plexes, [(Ph3P)2Pd2(R)2(µ-OH)2], where R ) Ph or Me, were
prepared as described in the literature.14 Organopalladium
iodo complexes of the type [(Ph3P)2Pd(I)Ar] were obtained in
the following manner. A mixture of 40% NaOH (20 g), PPh3
(2.4 g, 9.2 mmol), benzene (65 mL), [(Ph3P)2PdCl2] (2.0 g, 2.9
mmol), and benzyltriethylammonium chloride (0.1 g, 0.04
mmol) was vigorously stirred under N2 at room temperature
for 24 h. The mixture was then stirred at 65-75 °C until the
zerovalent palladium complex46 generated dissolved in the
organic phase. The bottom aqueous layer was carefully
separated by a pipette. After the yellow benzene solution was
allowed to cool to room temperature, powdered sodium iodide
(5-7 g)47 and an aryl iodide (3.5-5 mmol) were added and the
mixture was stirred under nitrogen for 15-30 min. The
arylpalladium iodo complexes were isolated in air. The
mixture was filtered, the solids were thoroughly extracted with
benzene,48 and the combined clear organic solutions were
reduced in volume and treated with excess ethanol. White or
yellowish crystals of the product were separated, washed with
ethanol and ether, and dried under vacuum. The yield of the
spectroscopically pure20 organopalladium iodo complexes was
in the range of 75-97%.
would increase the partial positive charge on the pal-
ladium,41 thus facilitating Pd-F ionization via the
nucleophilic path involving coordination of water to the
metal center (A). Hydrogen bonding between the F
ligand and an H atom of another (C) or the same (D)
water molecule provides electrophilic aid to the process.
To the contrary, when X is an electron-donating group,
the electrophilic path (B) may be dominant due to
stronger filled/filled repulsions,42 with nucleophilic sup-
port coming from the oxygen coordinated to the metal
(C and/or D). As a result, both relatively electron-
deficient and electron-rich σ-organic ligands in [(Ph3P)2-
Pd(R)F] speed up the water-induced Pd-F ionization.43
In concluding this article, we would like to remark
on conceptual analogies to mechanistic models C and
D, which can be found in various areas of chemistry. In
many instances, electrophiles provide aid to nucleophilic
reactions, whereas the presence of a nucleophile is
crucial for a number of electrophilic processes. For
example, SN2-type reactions between primary alcohols
and anionic nucleophiles (e.g., Br-) readily occur only
in the presence of a strong protic acid44 because proto-
nation of the OH function changes it into a much better
leaving group (eq 6). Similarly, electrophilic substitu-
The I/F exchange was performed under nitrogen in a
Schlenk-type flask immersed in a Branson 1200 ultrasonic
bath filled with water. Using flasks with a broad and desirably
flat bottom surface was found to be crucial for the synthesis,
as it prevented the dense silver salts from amassing in a thick,
(41) (a) In palladium complexes of the type [L2Pd(X)(4-C6H4Y)],
where L is a tertiary phosphine, X is a halogen, and Y is a π-acceptor
(e.g., NO2), both polar and resonance41b effects may be responsible for
an increase in the positive charge on the metal center. (b) Manna, J .;
Kuehl, C. J .; Whiteford, J . A; Stang, P. J . Organometallics 1997, 16,
1897.
(45) Reutov, O. A.; Beletskaya, I. P. Reaction Mechanisms of
Organometallic Compounds; North-Holland: Amsterdam, 1968. Makaro-
va, L. G.; Nesmeyanov, A. N. The Organic Compounds of Mercury;
North-Holland: Amsterdam, 1967.
(42) Caulton, K. G. New J . Chem. 1994, 18, 25.
(43) Among complexes of the type [(Ph3P)2Pd(4-XC6H4)F], the slow-
est exchange was observed for 8 (X ) Cl) in which the Pd-F bond is
polarized to the degree that is least favorable for hydrolysis via C- or
D-type path. Replacing the p-chlorophenyl ligand with a more electron-
donating one (1, 2, 5, or 6) facilitates the hydrogen bond formation,
whereas more electron-withdrawing groups (9 and 10) increase the
rate of nucleophilic attack on the metal. Both effects eventually result
in the elimination of the hydrated F- from the palladium. It is believed
that synergism of the two mechanisms, as shown in structures C or
D, is essential for efficient Pd-F ionization. The 1-naphthyl ligand in
7 is too remote from the F to impede its hydrogen bonding to water
but bulky enough to limit access of H2O to the metal center. As a result,
the water-induced ligand exchange in 7 is noticeably slower than in
1.
(46) Ioele, M.; Ortaggi, G.; Scarsella, M.; Sleiter, G. Polyhedron 1991,
10, 2475.
(47) The addition of NaI suppressed the formation of small amounts
(1-3%) of the corresponding organopalladium chloride, [(Ph3P)2Pd(Cl)-
Ar]. The latter apparently arose from ligand exchange between the
[(Ph3P)2Pd(I)Ar] formed and the Cl- present in droplets of the aqueous
phase, always remaining in the flask after the aqueous layer is
separated. Alternatively, to make the system Cl--free, the benzene
solution of the Pd(0) complex can be washed with a few portions of
water. However, because the washing must be done under nitrogen,
we found this less convenient than simply adding solid NaI to the
mixture.
(48) Unlike other [(Ph3P)2Pd(I)Ar] prepared in this work, the
p-chlorophenyl complex, [(Ph3P)2Pd(I)(4-C6H4Cl)], is only moderately
soluble in benzene and, hence, partially precipitates upon formation.
To assure a good isolated yield, the solid mixture of NaI and [(Ph3P)2-
Pd(I)(4-C6H4Cl)] should be thoroughly extracted with dichloromethane
and/or hot benzene.
(44) March, J . Advanced Organic Chemistry: Reactions, Mecha-
nisms, and Structure, 4th ed.; Wiley: NewYork, 1992. Bunton, C. A.
Nucleophilic Substitution at a Saturated Carbon Atom; Elsevier: New
York, 1963.

1780 Organometallics, Vol. 17, No. 9, 1998
Pilon and Grushin
stationary layer under the liquid phase. The reactions were
run in benzene, which had not been dried before the reaction,
at 10-25 °C in the dark. At lower temperatures the reaction
was slow, whereas at higher temperatures side reactions
occurred, resulting in lower yields and contamination of the
product. Occasional exposure of the reaction mixtures to light
for 5-10 min did not ruin or terminate the process. The
exchange was normally conducted with a 30-100% excess of
AgF, which was stored and handled under nitrogen in the
dark. Satisfactory results were obtained when the AgF
reagent had been briefly exposed to air for obtaining an
accurate weighing before the reaction. The fluorination of the
iodo complexes with AgF was monitored by 31P NMR analysis
of the liquid phase. Once the exchange process was complete,
the sonication was immediately stopped to avoid decomposition
of the desired fluorides.
[(P h 3P )2P d (F )P h ], 1. (a) A mixture of [(Ph3P)2Pd(I)Ph]
(162 mg, 0.19 mmol) and AgF (39 mg, 0.31 mmol) in benzene
(6 mL) was sonicated under N2 in the dark at 15-18 °C until
the iodo complex disappeared (2 h; 31P NMR control). The
solution was filtered through Celite, reduced in volume to ca.
2 mL, and treated with pentane to give 135 mg (96%) of 1 as
white crystals, which were separated, washed with pentane,
and dried under vacuum.
(b) A mixture of [(Ph3P)2Pd(I)Ph] (450 mg, 0.62 mmol), AgF
(118 mg, 0.93 mmol), and iodobenzene (7 µL, 0.06 mmol) in
benzene (10 mL) was sonicated under N2 in the dark at 18-
25 °C until the iodo complex disappeared (2.5 h; 31P NMR
control). The liquid phase was separated, and the solid was
extracted first with benzene (4 × 10 mL) and then with
dichloromethane (3 × 10 mL). The combined organic solutions
were filtered through a Celite plug, which was then washed
with dichloromethane (10 mL). The combined filtrates were
reduced in volume to ca. 5 mL and treated with hexane to give
385 mg (98%) of 1 as white crystals, which were separated,
washed with pentane, and dried under vacuum. 1H NMR
(CDCl3, 20 °C)49 δ: 6.2 (t, 2H, J ) 7.3 Hz, 3,5-C6H5Pd), 6.35
(t, 1H, J ) 7.0 Hz, 4-C6H5Pd), 6.55 (d, 2H, J ) 7.3 Hz, 2,6-
C6H5Pd), 7.1-7.6 (m, 30H, C6H5P).
[(P h 3P )2P d (F )Me], 2. TREAT HF (27.5 µL, 0.17 mmol)
was added to a suspension of [(Ph3P)2Pd2(Me)2(µ-OH)2] (202
mg, 0.25 mmol), PPh3 (140 mg, 0.53 mmol), and benzene (10
mL), and the mixture was stirred for 1 h. The benzene solution
was filtered through a short Celite plug, reduced in volume,
and treated with pentane to give 283 mg (84%) of spectroscopi-
cally pure 2 as a yellowish solid. Colorless crystals of 2 were
obtained by adding toluene (5 mL) to a saturated solution of
the yellowish material in dichloromethane, slowly evaporating
the mixture on a rotary evaporator at room temperature until
most of the dichloromethane was removed, and keeping the
resulting oversaturated toluene solution of 2 at -17 °C
overnight. 1H NMR (CDCl3, 20 °C) δ: -0.1 (t, 3H, J P-H ) 5.8
Hz, CH3Pd), 7.2-7.8 (m, 30H, C6H5P).
7.0 Hz, 4-C6H5Pd), 6.55 (d, 2H, J ) 7.3 Hz, 2,6-C6H5Pd), 7.1-
7.6 (m, 30H, C6H5P), 12.4 (br s, 1H, FHF). 31P NMR (CH2Cl2,
20 °C) δ: 20.2 (s).
[(P h 3P )2P d (HF 2)Me], 4. TREAT HF (200 µL, 1.24 mmol)
was added to a stirred mixture of [(Ph3P)2Pd2(Me)2(µ-OH)2]
(515 mg, 0.64 mmol), PPh3 (380 mg, 1.45 mmol), and benzene
(15 mL), and the mixture was vigorously stirred until the solids
dissolved and then stirred for 5 more min. The solution was
filtered through cotton wool, reduced in volume to ca. 3 mL,
and treated with ether (15 mL). The crystals were separated,
washed with ether, and dried under vacuum. The yield of
yellowish 4 was 760 mg (86%). Colorless crystals of the
spectroscopically pure 4 were obtained by recrystallization
from dichloromethane-toluene, as described in ref 31. 1H
NMR (CDCl3, 20 °C) δ: -0.1 (t, 3H, J P-H ) 5.8 Hz, CH3Pd),
7.2-7.8 (m, 30H, C6H5P), 12.4 (br s, 1H, FHF). 31P NMR (CH2-
Cl2, 20 °C) δ: 25.6 (s).
[(P h 3P )2P d (F )(4-C6H4CH3)], 5. A mixture of [(Ph3P)2Pd-
(I)(4-C6H4CH3)] (335 mg, 0.39 mmol), AgF (109 mg, 0.85 mmol),
p-iodotoluene (6 mg, 0.03 mmol), and benzene (10 mL) was
sonicated under N2 in the dark at 15-20 °C until the iodo
complex disappeared (5 h; 31P NMR control). The reaction
mixture was filtered through a Celite plug, which was thor-
oughly washed with benzene. The combined filtrates were
reduced in volume to ca. 5 mL and treated with excess pentane
to give white crystals of 5, which were washed with pentane
and dried under vacuum. The yield of 5 was 270 mg (92%).
1H NMR (CDCl3, 20 °C) δ: 1.9 (s, 3H, CH3), 6.1 (d, 2H, J H-H
) 8.0 Hz, 3,5-C6H4Pd), 6.4 (dt, 2H, J H-H ) 8.0 Hz, HH-P ) 1.7
Hz, 2,6-C6H4Pd), 7.2-7.7 (m, 30H, C6H5P).
[(P h 3P )2P d (F )(4-C6H4OCH3)], 6. A mixture of [(Ph3P)2-
Pd(I)(4-C6H4OCH3)] (476 mg, 0.55 mmol) and AgF (130 mg,
1.02 mmol) in benzene (15 mL) was sonicated under N2 in the
dark at 15-20 °C until the iodo complex disappeared (3 h; 31
P
NMR control). The reaction mixture was filtered through a
Celite plug, which was thoroughly washed with benzene. The
combined filtrates were reduced in volume to ca. 5 mL and
treated with pentane to give yellowish crystals of 6, which were
washed with pentane and dried under vacuum. The yield of
6 was 399 mg (96%). 1H NMR (CDCl3, 20 °C) δ: 3.5 (s, 3H,
CH3), 5.9 (d, 2H, J H-H ) 8.5 Hz, 3,5-C6H4Pd), 6.4 (dt, 2H, J H-H
) 8.5 Hz, HH-P ) 1.5 Hz, 2,6-C6H4Pd), 7.1-7.6 (m, 30H,
C6H5P).
[(P h 3P )2P d (F )(1-C10H7)], 7. A mixture of [(Ph3P)2Pd(I)(1-
C
10H7)] (224 mg, 0.25 mmol) and AgF (86 mg, 0.68 mmol) in
benzene (7 mL) was sonicated under N2 in the dark at 15-20
°C until the iodo complex disappeared (4 h; 31P NMR control).
The solution was filtered through a Celite plug, which was
then thoroughly washed first with benzene and then with
dichloromethane. The combined filtrates were reduced in
volume to ca. 5 mL and treated with pentane to give 193 mg
(98%) of 7 as pale-yellow crystals, which were separated,
washed with pentane, and dried under vacuum. 1H NMR
(CDCl3, 20 °C) δ: 6.4 (t, 1H J H-H ) 7.6 Hz, C10H7), 6.8-7.0
(m, 5H C10H7), 7.1-7.6 (m, 30H, C6H5), 8.4 (d, 1H J H-H ) 7.6
Hz, C10H7).
[(P h 3P )2P d (F )(4-C6H4Cl)], 8. A mixture of [(Ph3P)2Pd(I)-
(4-C6H4Cl)] (231 mg, 0.27 mmol) and AgF (70 mg, 0.55 mmol)
in benzene (9 mL) was sonicated under N2 in the dark at 15-
20 °C until the iodo complex disappeared (4 h; 31P NMR
control). The reaction mixture was transferred onto a Celite
plug, which was then thoroughly washed with benzene and
dichloromethane. The combined filtrates were reduced in
volume to ca. 5 mL and treated with hexane to give 175 mg
(86%) of 8 as greyish-white crystals, which were separated,
washed with hexane, and dried under vacuum. 1H NMR
(CDCl3, 20 °C) δ: 6.2 (d, 2H, J H-H ) 8.1 Hz, 3,5-C6H4Pd), 6.5
(d, 2H, J H-H ) 8.1 Hz, 2,6-C6H4Pd), 7.1-7.7 (m, 30H, C6H5P).
[(P h 3P )2P d (F )(4-C6H4CF 3)], 9. A mixture of [(Ph3P)2Pd-
(I)(4-C6H4CF3)] (574 mg, 0.64 mmol) and AgF (116 mg, 0.91
mmol) in benzene (10 mL) was sonicated under N2 in the dark
[(P h 3P )2P d (HF 2)P h ], 3. TREAT HF (215 µL, 1.32 mmol)
was added to a stirred mixture of [(Ph3P)2Pd2(Ph)2(µ-OH)2] (620
mg, 0.66 mmol), PPh3 (390 mg, 1.49 mmol), and benzene (35
mL), and the mixture was vigorously stirred until the solids
dissolved and then stirred for another 5 min. The solution
was filtered through a short Celite plug, which was then
washed with benzene (3 × 5 mL). The combined benzene
solutions were reduced in volume to ca. 10 mL, at which point
crystals of 3 started to deposit. To complete precipitation,
pentane (25 mL) was slowly added portionwise and the
mixture was left at room temperature for 2 h. The crystals
were separated, washed with pentane, and dried under
vacuum. The yield of 3 was 984 mg (98%). 1H NMR (CDCl3,
20 °C) δ 6.2 (t, 2H, J ) 7.3 Hz, 3,5-C6H5Pd), 6.35 (t, 1H, J )
(49) Interestingly, all four complexes of the type [(Ph3P)2Pd(Ph)X]
(X ) F, Cl, Br, and I) exhibit virtually indistinguishable 1H NMR
spectral patterns.

Synthesis of Organopalladium Complexes
Organometallics, Vol. 17, No. 9, 1998 1781
at 15-20 °C until the iodo complex disappeared (2 h; 31P NMR
control). The reaction mixture was filtered through a Celite
plug, which was thoroughly washed with benzene. The
combined filtrates were reduced in volume to ca. 5 mL and
treated with pentane to give 435 mg (82%) of 9‚1/2CH2Cl2 as
yellowish crystals, which were separated, washed with pen-
tane, and dried. 1H NMR (CDCl3, 20 °C) δ: 5.3 (s, 1H, CH2-
Cl2), 6.4 (dq, 2H, J H-H ) 8.3 Hz, J H-F ) 0.6 Hz, 3,5-C6H4Pd),
6.7 (dm, 2H, J H-H ) 8.3 Hz, 2,6-C6H4Pd), 7.2-7.7 (m, 30H,
C6H5P).
[(P h 3P )2P d (F )(4-C6H4NO2)], 10. A mixture of [(Ph3P)2Pd-
(I)(4-C6H4NO2)] (203 mg, 0.23 mmol) and AgF (61 mg, 0.48
mmol) in benzene (9 mL) was sonicated under N2 in the dark
at 15-20 °C until the iodo complex disappeared (4 h; 31P NMR
control). The reaction mixture was filtered through a Celite
plug, which was then thoroughly washed with benzene. The
combined filtrates were reduced in volume to ca. 5 mL and
treated with pentane to give 160 mg (90%) of 10 as yellowish
crystals, which were separated, washed with pentane, and
dried under vacuum. 1H NMR (CDCl3, 20 °C) δ: 6.8 (dt, 2H,
J H-H ) 9.0 Hz, HH-P ) 1.4 Hz, 2,4-C6H4Pd), 7.0 (d, 2H, J H-H
) 9.0 Hz, 3,5-C6H4Pd), 7.2-7.7 (m, 30H, C6H5P).
Ack n ow led gm en t. We are grateful to DuPont and
the Science and Technology Endowment Program (STEP)
at Wilfrid Laurier University for support of this re-
search. Prof. D. Gusev is acknowledged for discussion
of the NMR data.
OM9708440