Difluoro complexes of platinum(II) and -(IV) with monodentate phosphine ligands: An exceptional stability of d6 octahedral organometallic fluorides

Article abstract of DOI:10.1021/ic0488177

Complexes (R₃P)₂PtF₂ were prepared by reaction of the corresponding diiodo precursors with AgF in dichloromethane. The intermediate formation of trans- and cis-(R₃P)₂Pt(I)F was also observed. All fluoro complexes demonstrate a strong preference for the cis-configuration (R = Ph or Et) unless a bulky phosphine ligand is used (R = i-Pr), in which case the trans complex was observed. The Pt(IV) difluoro compounds (R₃P)₂Ar₂PtF₂ were obtained by reacting the Pt(II) diaryl precursors with XeF₂. The fluoro ligands are located in the trans-position relative to the aryl groups in the overall octahedral environment. The representative Pt(II) and Pt(IV) difluoro complexes were characterized by X-ray crystallography. All fluoro compounds react rapidly with chlorotrimethylsilane to give the corresponding chloro complexes. The Pt(IV) difluorides are remarkably stable in the C-C reductive elimination reaction, relative to their dichloro analogs which reductively eliminate diaryl within several hours at 45°C in N-methylpyrrolidone. It was found that phosphine dissociation from the octahedral Pt(IV) complex is essential for the reductive elimination reaction to take place, the difluoro complex being kinetically stable even at 60°C.

Full text of DOI:10.1021/ic0488177

Inorg. Chem. 2005, 44, 1547−1553
Difluoro Complexes of Platinum(II) and -(IV) with Monodentate
Phosphine Ligands: An Exceptional Stability of d6 Octahedral
Organometallic Fluorides
Anette Yahav, Israel Goldberg, and Arkadi Vigalok*
School of Chemistry, The Raymond and BeVerly Sackler Faculty of Exact Sciences,
Tel AViV UniVersity, Tel AViV 69978, Israel
Received August 26, 2004
Complexes (R3P)2PtF2 were prepared by reaction of the corresponding diiodo precursors with AgF in dichloromethane.
The intermediate formation of trans- and cis-(R3P)2Pt(I)F was also observed. All fluoro complexes demonstrate a
strong preference for the cis-configuration (R
) Ph or Et) unless a bulky phosphine ligand is used (R ) i-Pr), in
which case the trans complex was observed. The Pt(IV) difluoro compounds (R3P)2Ar2PtF2 were obtained by reacting
the Pt(II) diaryl precursors with XeF2. The fluoro ligands are located in the trans-position relative to the aryl groups
in the overall octahedral environment. The representative Pt(II) and Pt(IV) difluoro complexes were characterized
by X-ray crystallography. All fluoro compounds react rapidly with chlorotrimethylsilane to give the corresponding
chloro complexes. The Pt(IV) difluorides are remarkably stable in the C
to their dichloro analogs which reductively eliminate diaryl within several hours at 45
was found that phosphine dissociation from the octahedral Pt(IV) complex is essential for the reductive elimination
reaction to take place, the difluoro complex being kinetically stable even at 60 C.
−C reductive elimination reaction, relative
°
C in N-methylpyrrolidone. It
°
Introduction
reactions, start to appear in the literature.6,7 Still, palladium
and platinum phosphine complexes with more than one
fluoro ligand were believed to be too unstable to be isolated
in their pure form.6a,8 The reasons for the limited stability
of late transition metal complexes with the fluoride ligand
Palladium and platinum phosphine complexes are of great
interest to organometallic chemistry and catalysis.1 Many
important textbook examples of oxidative addition, reductive
elimination, and ligand exchange reactions have been
performed on such complexes.2 In most of these transforma-
tions the participation of a metal halide complex is involved,
with chloride, bromide, or iodide being the natural ligands
of choice. In contrast, little is known about palladium and
platinum phosphine complexes containing a fluoro ligand.3-5
Only recently did adequately characterized fluoro complexes,
which show high reactivity in nucleophilic substitution
(4) For reviews on C-F bond activation, see: (a) Burdeniuc, J.; Jedlicka,
B.; Crabtree, R. H. Chem. Ber./Recueil 1997, 130, 145. (b) Kiplinger,
J. L.; Richmond, T. G.; Osterberg, C. E. Chem. ReV. 1994, 94, 373.
(c) See also: Braun, T.; Perutz, R. N. Chem. Commun. 2002, 2749
and references therein.
(5) For reviews on fluoro complexes in catalysis, see: (a) Fagnou, K.;
Lautens, M. Angew. Chem., Int. Ed. 2002, 41, 26. (b) Pagenkopf, B.
L.; Carreira, E. M. Chem.sEur. J. 1999, 5, 3437.
(6) (a) Fraser, S. L.; Antipin, M. Y.; Khroustalyov, V. N.; Grushin, V. V.
J. Am. Chem. Soc. 1997, 119, 4769. (b) Pilon, M. C.; Grushin, V. V.
Organometallics 1998, 17, 1774. (c) Marshall, W. J.; Thorn, D. L.;
Grushin, V. V. Organometallics 1998, 17, 5427.
(7) Several Pt(II) monofluoride complexes have been reported; see for
example: (a) Nilsson, P.; Plamper, F.; Wendt, O. F. Organometallics
2003, 22, 5235. (b) Clark, H. C. S.; Fawcett, J.; Holloway, J. H.; Hope,
E. G.; Peck, L. A.; Russel, D. R. J. Chem. Soc., Dalton Trans. 1998,
1249. (c) Coulson, D. R. J. Am. Chem. Soc. 1976, 98, 3111. (d)
Bernhardt, P. V.; Gallego, C.; Martinez, M.; Parella, T. Inorg. Chem.
2002, 41, 1747. (e) Doherty, N. M.; Critchlow, S. C. J. Am. Chem.
Soc. 1987, 109, 7906. (f) Cairns, M. A.; Dixon, K. R.; McFarland, J.
J. J. Chem. Soc., Dalton Trans. 1975, 1159. (g) Russell, D. R.; Mazid,
M. A. J. Chem. Soc., Dalton Trans. 1980, 1737.
* Author to whom correspondence should be addressed. E-mail: avigal@
post.tau.ac.il. Tel.: 972-3-640 8617. Fax: 972-3-640 6205.
(1) (a) Tsuji, J. Palladium Reagents and Catalysts: InnoVations in Organic
Synthesis; John Wiley & Sons: New York, 1997. (b) Strukul, G. Top.
Catal. 2002, 19, 33. (c) Clarke, M. L. Polyhedron 2001, 20, 151.
(2) (a) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Sausalito, CA, 1987. (b) Atwood, J. D.
Inorganic and Organometallic Reaction Mechanisms, 2nd ed.; VCH
Publishers: New York, 1997.
(3) For general reviews, see: (a) Grushin, V. V. Chem.sEur. J. 2002, 8,
1007. (b) Murphy, E. F.; Murugavel, R.; Roesky, H. W. Chem. ReV.
1997, 97, 3425. (c) Doherty, N. M.; Hoffman, N. W. Chem. ReV. 1991,
91, 553.
(8) (a) Mason, M. R.; Verkade, J. G. Organometallics 1992, 11, 2212.
(b) Organometallics 1990, 9, 864. (c) Grushin, V. V. Organometallics
2000, 19, 1888.
10.1021/ic0488177 CCC: $30.25
Published on Web 02/03/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 5, 2005 1547

Yahav et al.
Scheme 1
are hard to evaluate conclusively, and it is often attributed
to incompatibility of a “soft” transition metal acid with a
very “hard” fluoride base.3,9 Recently, Mezzetti and co-
workers revisited the “hardening” the metal center, via either
coordinative unsaturation or electrostatic interactions, as an
essential requirement for metal-fluoride stabilization.10
Unfavorable pπ-dπ four electron repulsions may also be
operative in late transition metal fluoro complexes.11,12 The
π-donation properties of the fluoride ion are strongest among
the halide ligands, a notion supported by CO IR frequency
analysis.13 Due to the relative shortage of the late transition
metal fluoro complexes, the experimental and theoretical
comparative studies were often performed on different metal
systems, which varied in the number and types of ligands,
and their coordination geometries.10,11
We recently reported the first palladium(II) and platinum-
(II) complexes of the formula L2MF2, where L2 is a cis-
chelating diphosphine ligand (eq 1).14 We hereby present the
extension of our studies toward the synthesis and comparative
reactivity of a series of Pt(II) and Pt(IV) difluoro complexes
with monodentate phosphine ligands. Our results indicate
that such complexes may be more common than previously
believed and that the fluoro ligand can have a stabilizing
effect on its metal complexes.
characterized (R3P)2MF2 (M ) Pd, Pt) complexes reported
by us.14 While the analogous palladium(II) complexes could
only be isolated with the cis-chelating trialkylphosphine
ligands, the platinum complexes were also obtained with cis-
chelating arylphosphines as well as the monodentate triph-
enylphosphine. In the latter case, the formation of the trans-
(Ph3P)2PtF2 was mistakenly reported.14
We found that cis-(Ph3P)2PtF2 (2a) can be readily prepared
by reacting (Ph3P)2PtI2 (1a) with 3 equiv of AgF in CH2Cl2
for 3 h (Scheme 1). The 31P (5.03 ppm) and 19F NMR
(-216.34 ppm) spectra of 2a exhibit the characteristic
AA′MXX′ pattern (for the 195Pt isotope) with a calculated
trans-JPF of 180.0 Hz. Performing the reaction with 1 equiv
of AgF in CH2Cl2 showed the formation of small amounts
of trans-(Ph3P)2Pt(I)F (3a) as an intermediate in the halide
exchange reaction. Slowing the reaction, using benzene as a
solvent, resulted in the formation of 3a as a major reaction
product. The 19F NMR spectrum of 3a showed a triplet at
-310.38 ppm (JPF ) 19.1 Hz, JPtF ) 543.1 Hz), while the
31P NMR spectrum showed the doublet at 13.61 ppm (JPtP
) 2747.1 Hz). Similarly, reacting trans-(Et3P)2PtI2 with 3
equiv of AgF gave the cis-difluoro complex 2b (19F NMR,
-225.31 ppm; AA′MXX′ for the 195Pt isotope), and the
corresponding trans-intermediate 3b was observed during the
reaction (triplet in 19F NMR spectrum at -335.20 ppm, JPF
) 18.6 Hz, JPtF ) 494.4 Hz). Upon being warmed to 45 °C,
trans-3b underwent clean conversion to cis-3′b. Thus, there
is a strong thermodynamic preference for the overall cis-
configuration in both mono- and difluoroplatinum(II) com-
plexes. Interestingly, there is a dramatic difference (ca. 90
ppm) in the 19F NMR chemical shifts upon moving from
the trans-3b to cis-3′b, which exhibited a doublet of doublets
in the 19F NMR spectrum at -248.10 ppm (JPtransF ) 166.9
Hz, JPcisF ) 22.3 Hz).17
Results and Discussion
1. Synthesis and Reactivity of Platinum(II) Difluoro
Complexes. While palladium(II) and, especially, platinum-
(II) square planar complexes of the formula (R3P)2MX2 (X
) Cl, Br, I) have been extensively studied to evaluate kinetic
and thermodynamic parameters of ligand exchange pro-
cesses,15 similar studies on fluorides have been hindered by
the instability of such complexes. Several claims to have
made the difluoro platinum complexes bearing phosphine
ligands did not provide definitive characterization of the
resulting products.16 Only recently were the first fully
(9) Mezzetti, A.; Bekker, C. HelV. Chim. Acta 2002, 85, 2686.
(10) Becker, C.; Kieltsch, I.; Broggini, D.; Mezzetti, A. Inorg. Chem. 2003,
42, 8417.
(11) Caulton, K. G. New J. Chem. 1994, 18, 25.
(12) Meyer, J. M. Comments Inorg. Chem. 1988, 8, 125.
(13) Poulton, J. T.; Sigalas, M. P.; Folting, K.; Streib, W. E.; Eisenstein,
O.; Caulton, K. G. Inorg. Chem. 1994, 33, 1476.
(14) Yahav, A.; Goldberg, I.; Vigalok, A. J. Am. Chem. Soc. 2003, 125,
13634.
(15) (a) Basolo, F.; Chatt, J.; Gray, H. B.; Pearson, R. G.; Shaw, B. L. J.
Chem. Soc. 1961, 2207. (b) Cooper, D. G.; Powell, J. J. Am. Chem.
Soc. 1973, 95, 1102. (c) Verstuyft, A. W.; Nelson, J. H. Inorg. Chem.
1975, 14, 1501. (d) Anderson, G. K.; Cross, R. J. Chem. Soc. ReV.
1980, 185.
(16) (a) McAvoy, J.; Moss, K. C.; Sharp, D. W. A. J. Chem. Soc. 1965,
1376. (b) Kemmitt, R. D. W.; Peacock, R. D.; Stocks, J. J. Chem.
Soc. A 1971, 846. (c) Bland, W. J.; Kemmitt R. D. W. J. Chem. Soc.
A 1969, 2062. (d) Thomson, J.; Fzea, A. H.; Lobban, J.; McGivern,
P.; Cairns, J. A.; Fitzgerald, A. G.; Berry, G. J.; Davidson, M. R.;
Fan, Y. C. MRS Symp. Proc. 1999, 546, 225.
When trans-(i-Pr3P)2PtI2 was treated with an excess of AgF
in CH2Cl2 for 3 h, the formation of trans-(i-Pr3P)2Pt(I)F (3c)
was observed as the major compound. Complex 3c showed
a triplet at -329.68 ppm (JPF ) 12.6 Hz, JPtF ) 520.6 Hz)
in the 19F NMR spectrum and a doublet at 31.09 ppm in the
(17) For a brief discussion on 19F NMR chemical shifts in late transition
metal complexes, see: Huang, D.; Koren, P. R.; Folting, K.; Davidson,
E. R.; Caulton, K. G. J. Am. Chem. Soc. 2000, 122, 8916.
1548 Inorganic Chemistry, Vol. 44, No. 5, 2005

Difluoro Complexes of Platinum(II) and -(IV)
Scheme 3
(Scheme 2). Complexes 5 show first-order patterns in their
19F and 31P NMR spectra (Experimental Section), in agree-
ment with the proposed cis-orientation of the two phosphine
ligands. Similarly, reacting 2 with <2 equiv of Me3SiI gave
a mixture of unreacted 2, cis-diodo complexes 1, and the
monosubstituted complex cis- (R3P)2Pt(I)F (3′a,b). Thus, the
reactivity of the Pt(II) difluoro complexes 2 is similar to that
observed for the Pd(II) and Pt(II) monofluoro complexes,
which rapidly fluorinate strongly electrophilic organic re-
agents.6,7
Figure 1. Selected bond distances (Å) and bond angles (deg) for a
molecule of 2a: Pt-F1 1.999(2), Pt-F2 2.016(2), Pt-P1 2.2198(9), Pt-
P2 2.2304(10); F1-Pt-F2 84.81(9), F1-P-P1 91.05(7), F1-Pt-P2
169.92(7), F2-Pt-P1 175.74(7), F2-Pt-P2 85.27(7), P1-Pt-P2 98.89-
(3).
2. Synthesis and Reactivity of the Platinum(IV) Dif-
luoro Complexes. A Pt(IV) difluoro complex was previously
observed with only pyridine ligands, and no corresponding
phosphine complexes were reported.19 We prepared the bis-
(triphenylphosphine)platinum(IV) difluoro complex 7a by
reacting the diphenylplatinum(II) precursor (6a) with XeF2
in CH2Cl2 (Scheme 3).20 This reaction was previously
reported to produce the trans-(Ph3P)2PtF2.14 The assignment
was based on the 31P and 19F NMR spectra, which showed
the expected pattern of two phosphine and two fluoro ligands
being symmetrical and in the mutual cis-arrangement. While
formation of biphenyl and the corresponding cis-(R3P)2PtF2
complexes was observed with cis-chelating diphosphine
ligands (eq 1), only trace amounts of carbon-carbon
reductive elimination products were obtained in the reaction
of 6a with XeF2. As monitoring the formation of biphenyl
Scheme 2
31P NMR spectrum. Prolonged treatment (2 days) with an
excess of AgF did not produce pure trans-(i-Pr3P)2PtF2 (2c)
although it was obtained as the major complex as indicated
by a triplet at -455.90 ppm (JPF ) 11.2 Hz, JPtF ) 973.6
Hz) in the 19F NMR spectrum and a triplet at 34.87 ppm
(JPtP ) 2822.4 Hz) in the 31P NMR spectrum. Large amounts
of decomposition products were also observed in this case.
Colorless crystals of 2a were obtained by slow pentane
diffusion into the CH2Cl2 solution. The platinum center is
located in the square planar arrangement (Figure 1) with the
angle between the two fluoro ligands (84.81(9)°) being
substantially smaller than that between the two phosphine
ligands (98.89(3)°), indicating steric repulsions between the
latter. The Pt-F1 and Pt-F2 distances of 1.999(2) and
2.016(2) Å, respectively, are significantly shorter than in
trans-(Ph3P)2Pt(Ph)F (2.117(3) Å).7a The fluoro ligands are
also involved in intermolecular interactions with aromatic
hydrogens of the phosphine ligands (2.276 and 2.376 Å).
Shorter Pt-P bond distances in 2a (2.2198(9) and 2.2304-
(10) Å) compared with those in cis-(Ph3P)2PtCl2 (2.251(2)
and 2.265(2) Å)18 provide evidence of the weak trans-
influence of the fluoride.
1
by H NMR was obscured by triphenylphosphine aromatic
signals, we also prepared the para-fluorophenyl analogs 6b
and 7b, which would show the characteristic singlet in the
19F NMR spectrum at -115.8 ppm if the formation of 4,4′-
difluorobiphenyl occurred during the reaction.
The 19F NMR spectrum of 7b shows a broad singlet at
-255.22 ppm, which resolves into a triplet (JPtF ) 122.3
Hz) in N-methylpyrrolidinone (NMP). Complex 7b also
shows a singlet at -119.83 ppm due to the para-fluoro
substituent. The 31P NMR spectrum of 7b exhibits a triplet
at 8.32 ppm with Pt-P satellite signals of 2070.4 Hz. Similar
to the triphenylphosphine complexes, the corresponding Pt-
(IV) complexes 7c,d, containing the trialkylphosphine ligands
(Et3P and i-Pr3P), were also prepared using the same
procedure (Scheme 1). Complex 7c shows a triplet in the
31P NMR spectrum at 7.03 ppm (JFP ) 21.5 Hz, JPtP ) 1877.7
Complexes 2a,b reacted rapidly with 2 equiv of chloro-
(trimethyl)silane (Me3SiCl) to give Me3SiF and the cis-
dichloro complexes 4a,b (Scheme 3). When less than 2 equiv
of the organic chloride was used, a mixture of 2, 4, and the
monosubstituted complex cis-(R3P)2Pt(Cl)F (5a,b) was formed
(19) Drews, H.-H.; Preetz, W. Z. Anorg. Allg. Chem. 1997, 623, 509.
(20) For use of XeF2 in synthesis of metal fluoro complexes, see: (a)
Cockman, R. W.; Ebsworth, E. A. V.; Holloway, J. H.; Murdoch, H.;
Robertson, N.; Watson, P. G. In Fluorine Chemistry (Toward the 21st
Century); Thrasher, J. S., Strauss, S. H., Eds.; American Chemical
Society: Washington, DC, 1994; Chapter 20, p 327. (b) Holloway, J.
H.; Hope, E. G. J. Fluorine Chem. 1996, 76, 209.
(18) Anderson, G. K.; Clark, H. C.; Davies, J. A.; Ferguson, G.; Parvez,
M. J. Crystallogr. Spectrosc. Res. 1982, 12, 449.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1549

Yahav et al.
Scheme 4
Scheme 5
dichloro complexes 8a-c (Scheme 4). Replacement of the
fluoro ligand in 7b with the chloride results in the upfield
shift of the aromatic fluoro signal in the 19F NMR spectrum,
which appears at -121.03 ppm in 8b. It also results in the
decrease in JPtP by ca. 100 Hz in the 31P NMR spectrums
an indication of lower electron density at the metal center.24
Similar to 2, addition of less than 2 equiv of Me3SiCl in
CH2Cl2 or NMP gave a mixture of 7, 8, and the monosub-
stituted complex 9 (Scheme 4). Complexes 7 reacted with
Me3SiCl at significantly slower rates than complexes 2. When
a 10:1 mixture of 7b and 2a was treated with 1 equiv of
Me3SiCl (per 2a), only 5a was observed in the 19F NMR
spectrum along with the unreacted 2a and 7b. Formation of
5a was also noted in the 31P NMR spectrum. However, reac-
tion of an NMP solution of 7b with 2 equiv of Me3SiOTf
resulted in the monosubstituted complex 10b as the only
product (Scheme 5).
Figure 2. Selected bond distances (Å) and bond angles (deg) for a
molecule of 7a: Pt-F1 2.0892(14), Pt-C1 2.039(2), Pt-P1 2.3846(6); C1-
Pt-C1′ 95.30(14), C1-Pt-F1 86.56(9), C1-Pt-F1′ 176.94(7), F1-Pt-
F1′ 91.70(8), P1-Pt-P1′ 171.45(3).
Hz) and a triplet in the 19F NMR spectrum at -270.89 ppm
(JPtF ) 104.3 Hz) in NMP. In the case of 7d the resulting
complex could not be purified due to its high solubility in
hexane.
Crystals of 7a, suitable for single-crystal X-ray analysis,
were obtained by slow evaporation of its CH2Cl2 solution.
The crystal structure of 7a (Figure 2) shows the platinum
atom in a distorted octahedral environment, with the phos-
phine ligands tilted toward the fluorides (P1-Pt-P1′ )
171.45(3)°). The platinum fluoride distances of 2.0892(14)
Å are slightly shorter than those in trans-(Ph3P)2Pt(Ph)F
(2.117(3) Å),7a while the Pt1-C1 distance of 2.039(2) Å is
longer than that in the Pt(II) case (1.978(5) Å). The Pt-F1
distance in 7a also correlates well with Pt-F distances in
Pt(II) complexes that have the fluoro ligand trans to the
phosphine (2.043(7) and 2.03(1) Å in (Et3P)3PtF+ and cis-
(Ph3P)2Pt(CH(CF3)2)F, respectively).7f,21 It is, however, sig-
nificantly longer than the Pt-F bonds in the trans-(py)4PtF22+
complex (1.938(10) and 1.943(10) Å).19 The C1-Pt-C1′
angle of 95.30(14)° is larger than C1-Pt-F1 (86.56(9)°) as
a result of steric repulsions between the bulkier phenyl
groups. These repulsions are further evident in the significant
deviation (30.91°) of the two phenyl ligands from the
equatorial plane.22 There is a strong interaction between the
fluoro ligands and one of the aromatic protons of each Ph3P,
manifested in the very short nonbonding distance of 2.059
Å.23 The intramolecular and intermolecular nonbonding
interactions between one of the aromatic hydrogens of the
phenyl substituent and the fluoro ligands (2.491 and 2.367
Å, respectively) are also worth noting.
This compound could be isolated by performing the
reaction in a toluene-NMP (9:1) mixture followed by the
precipitation of 10b with hexane. No formation of the
disubstituted product was observed, even when an excess
(3-5 equiv) of Me3SiOTf was used. The 19F NMR spectrum
of 10b showed a triplet at -274.52 ppm (JPtF ) 97.0 Hz)
and two singlets, due to inequivalent fluorine atoms of the
aromatic ligands, at 118.70 and 118.04 ppm. The 31P NMR
spectrum of 10b exhibited a doublet at 4.27 ppm. The
reaction with Me3SiOTf is solvent dependent. A different
reactivity pattern was observed in CH2Cl2, where substitution
of both fluoro ligands occurs rapidly to give 2 equiv of
Me3SiF and the ditriflate complex. The latter could not be
isolated at room temperature, and a number of decomposition
products were observed. While the polarity of CH2Cl2 is
significantly lower than that of NMP (ꢀ ) 9 vs 32.5,
respectively),25 it is inclined to form hydrogen bonds with
the coordinated fluoride.26 Thus, it is possible that, in a
CH2Cl2 solution, formation of hydrogen bonds might be
responsible for the higher lability and reactivity of the fluoro
Reacting complexes 7a-c with 2 equiv of Me3SiCl
resulted in the rapid formation of Me3SiF and the Pt(IV)
(24) (a) Cobley, C. J.; Pringle, P. G. Inorg. Chim. Acta 1997, 265, 107.
(b) Mather, G. G.; Rapsey, G. J. N.; Pidcock, A. Inorg. Nucl. Chem.
Lett. 1973, 9, 567.
(25) Abboud, J.-L. M.; Notario, R. Pure Appl. Chem. 1999, 71, 645.
(26) Grushin, V. V.; Marshall, W. J. Angew. Chem., Int. Ed. 2002, 41,
4476.
(21) Howard, J.; Woodward, P. J. Chem. Soc., Dalton Trans. 1973, 1840.
(22) Flemming, J. P.; Pilon, M. C.; Borbulevitch, O. Y.; Antipin, M. Y.;
Grushin, V. V. Inorg. Chim. Acta 1998, 280, 87.
(23) Barthazy, P.; Stoop, R. M.; Worle, M.; Togni, A.; Mezzetti, A.
Organometallics 2000, 19, 2844.
1550 Inorganic Chemistry, Vol. 44, No. 5, 2005

Difluoro Complexes of Platinum(II) and -(IV)
Scheme 6
Although ligand dissociation could provide partial relief of
the filled-filled pπ-dπ repulsions present in the octahedral
configuration,11,31,32 this would only happen if the resulting
unsaturated complex adapted a trigonal bipyramidal config-
uration. In our system, phosphine dissociation would only
result in a square pyramidal structure due to the presence of
two fluoro ligands trans to two aryl groups.
Scheme 7
The overall stability of the Pt(IV) fluoro complexes in
comparison with the corresponding chloro analogs is a rare
example of a dramatic reactivity change upon replacing one
halide with another.33,34
3. Summary. Platinum(II) square planar complexes (R3P)2-
PtF2 were prepared and fully characterized. These compounds
exhibit a strong preference for the cis-geometry, unless steric
hindrance (R ) i-Pr) exists. We also prepared octahedral
Pt(IV) difluoro complexes (R3P)2Ar2PtF2 with the fluoro
ligands in the trans position to the aryl groups. The platinum-
(II) and platinum(IV) difluoro complexes are stable at room
temperature in both solution and the solid state, although
they rapidly fluorinate strong organic electrophiles. Interest-
ingly, the fluoro ligands stabilize Pt(IV) complexes which
show greater stability in the C-C reductive elimination
reaction than the analogous dichoro complexes. This stabi-
lization is caused by stronger binding of the phosphine ligand
in the Pt(IV) fluoro complexes, as phosphine dissociation
from the octahedral complex was found to be essential for
the reductive elimination process.
ligand compared with that in an NMP solution. This notion
is supported by the broadening of the 19F NMR signals in 7
in CH2Cl2 vs NMP. The addition of a 5-10-fold excess of
methanol to solutions of 7b,c in NMP caused no changes in
their 19F and 31P NMR spectra over the period of 1 day.
While complex 7b was stable when heated at 60 °C in
NMP overnight, complex 8b underwent a rapid reductive
elimination to give 4 and 4,4′-difluorobiphenyl quantitatively
within 5 h at 45 °C (Scheme 6). The formation of the latter
was confirmed by 19F NMR spectroscopy, EI-MS, and an
authentic sample. The Pt(IV) Et3P complexes were signifi-
cantly more stable toward the reductive elimination, with
both 2c and 8c unchanged after 12 h at 80 °C. Interestingly,
10b is less reactive toward the C-C reductive elimination
than 8b, even though the platinum center is less electron
rich and a highly labile ligand (OTf-) is present.27 The C-C
reductive elimination from a Pt(IV) center is generally
preceded by ligand dissociation28 and, thus, could greatly
benefit from the presence of a labile ligand, such as
triflate.29,30 Therefore, the presence of a single fluoro ligand
in 10b is sufficient to overcome both the electronic and
(anionic) ligand lability factors (when compared with 8b)
that generally strongly facilitate the reductive elimination
processes. When a 10-fold excess of Ph3P was added to a
solution of 8b in NMP, very little C-C reductive elimination
was observed after 5 h at 45 °C. Addition of a 10-fold excess
of (p-Tolyl)3P to a solution of 7b in NMP showed no ligand
exchange at 60 °C, while complex 8b underwent a complete
exchange reaction giving (p-Tolyl)3P2Pt(Ar)2Cl2 at 45 °C
after 5 h (Scheme 7).
Experimental Section
General Methods. All operations with air- and moisture-sensitive
compounds were performed in a nitrogen-filled Innovative Technol-
ogy glovebox. All solvents were of reagent grade or better. Hexane,
toluene, benzene, and THF were distilled over sodium/benzophe-
none ketyl. CH2Cl2 and NMP were refluxed over CaH2 and distilled.
All solvents were degassed and stored under high-purity nitrogen
after distillation. All deuterated solvents (Aldrich) were stored under
high-purity nitrogen on molecular sieves (3 Å). Commercially
available reagents were used as received. Silver(I) fluoride and
xenon difluoride were purchased from Matrix Scientific. Caution:
XeF2 is a strong oxidant and may cause a fire upon contact with
combustible materials. (R3P)2PtAr2 were prepared by ligand
exchange with (1,5-cyclooctadiene)PtAr2 as previously reported.35
1H, 31P, 19F, and 13C NMR spectra were recorded on Bruker AC
1
200 MHz and Bruker AMX 400 MHz spectrometers. H and 13C
NMR signals are reported in ppm downfield from TMS. 1H signals
are referenced to the residual proton (7.26 ppm for CDCl3) of a
The reduced lability of the phosphine ligand in the difluoro
complex 7b can be attributed to lower electron density at
the metal center bound to the most electronegative atom.
(31) (a) Riehl, J.-F.; Jean, Y.; Eisenstein, O.; Pelissier, M. Organometallics
1992, 11, 729. (b) Albright, T. A.; Burdett, J. K.; Whangbo, M.-H.
Orbital Interactions in Chemistry; John Wiley & Sons: New York,
1985; Chapters 15-17, p 277.
(32) Fluoride is the strongest π-donor among halides: (a) Smart, B. E. In
Chemistry of Organic Fluorine Compounds II; Hudlicky, M., Pavlath,
A. E., Eds.; American Chemical Society: Washington, DC, 1995;
Chapter 6, p 979. (b) Hammet constants σp: F, 0.06; Cl, 0.23; Br,
0.23; I, 0.18. Hansch, C.; Leo, A.; Taft, R. W. Chem. ReV. 1991, 91,
165.
(27) Continued heating at higher temperatures gave a number of decom-
position products, which could be the result of instability of (Ph3P)2-
PtF(OTf), formed after the reductive elimination step. See: Thorn,
D. L. Organometallics 1998, 17, 348 and ref 7b.
(28) For proposed aryl-aryl C-C reductive elimination from a 18 electron
Pt(IV) center, see: Edelbach, B. L.; Lachicotte, R. J.; Jones, W. D. J.
Am. Chem. Soc. 1998, 120, 2843.
(29) (a) Williams, B. S.; Goldberg, K. I. J. Am. Chem. Soc. 2001, 123,
2576. (b) Crumpton, D. M.; Goldberg, K. I. J. Am. Chem. Soc. 2000,
122, 962.
(33) Cooper, A. C.; Folting, K.; Huffman, J. C.; Caulton, K. G. Organo-
metallics 1997, 16, 505.
(30) For general review on C-C reductive elimination, see: (a) Brown, J.
M.; Cooley, N. A. Chem. ReV. 1988, 88, 1031. See also: (b) Stang,
P. J.; Kowalski, M. H. J. Am. Chem. Soc. 1989, 111, 3356. (c)
Puddephatt, R. J. Angew. Chem., Int. Ed. 2002, 41, 261.
(34) Grushin, V. V.; Marshall, W. J. J. Am. Chem. Soc. 2004, 126, 3068.
(35) (a) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411.
(b) Eaborn, C.; Odell, K. J.; Pidcock, A. J. Chem. Soc., Dalton Trans.
1978, 357.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1551

Yahav et al.
Table 1. Selected 19F NMR Signals of Complexes 2-10
Table 2. Crystal Structure Information for Complexes 7a and 2a
complex
2a
19F signal (ppm)a
J
PtF (Hz)
JPF (Hz)
7a
2a
-216.34
108.0b
180.0b
18.0
empirical formula
fw
temp (K)
wavelength (å)
radiatn type
cryst system
space group
unit cell dimens
a (Å)
C48H40F2P2Pt
911.83
C36H30F2P2Pt
757.63
2b
2c
3a
3′a
-225.31b
-455.90c
-310.38d
-246.99d
110(2)
0.710 73
Mo KR
110(2)
0.710 73
Mo KR
973.6
543.1
68.8
11.2
19.1
181.9
28.6
18.6
166.9
22.3
12.6
23.6
21.5
monoclinic
C2/c
monoclinic
P21/c
3b
3′b
-335.20c
-248.10d
494.4
20.5030(3)
9.85000(10)
19.2560(3)
90.00
102.0220(5)
90.00
9.7590(2)
33.2970(9)
10.0480(2)
90.00
116.1981(13)
90.00
b (Å)
c (Å)
3c
7a
7b
-329.68c
520.6
-252.49
104.2d
122.3b
R (deg)
-255.22
â (deg)
-119.83
γ (deg)
7c
7d
-270.89
104.3d
21.6
17.8
19.9
22.2
18.8
20.2
cell vol (Å3)
Z
3803.55(9)
4
2929.64(12)
4
-119.71
-261.03c
calcd density (g m-3
cryst descriptn
cryst size (nm)
)
1.592
1.718
-120.74
colorless prisms
colorless prisms
9b
-280.31c
0.20 × 0.20 × 0.15 0.20 × 0.15 × 0.15
-121.93, -121.86
θ range for data collcn (deg) 2.45-27.86
2.34-28.24
0 e h e 12
0 e k e 43
9c
-281.92c
index ranges
0 e h e 26
0 e k e 12
EnDash25 e l e 24 EnDash13 e l e 12
4509/4288
full-matrix F2
1.054
4509/0/240
0.0249
-120.99, -120.22
-274.52d
10b
10c
97.0
75.9
-118.70, -118.04
reflcns collcd/unique
refinement method
goodness-of-fit
data/restrains/params
R1 (I > 2σ(I))
wR2 (all data)
6932/5681
full-matrix F2
1.026
6932/0/370
0.0450
-263.81e
-117.69, -116.93
a The signals are reported in CDCl3, unless stated otherwise. b AA′MXX′
system (∼30%). c In CH2Cl2. d In NMP. e In C6D6.
0.0588a
0.0736b
2
2
2
a w )1/[σ2(Fo ) + (0.0311P)2 + 6.4988P], where P ) (Fo + 2Fc )/3.
deuterated solvent, and for 13C NMR spectra, the signal of CDCl3
(77.00 ppm) was used as a reference. 31P chemical shifts are reported
in ppm downfield from H3PO4 and referenced to an external 85%
phosphoric acid sample. 19F chemical shifts are reported in ppm
downfield from CClF3 and referenced to an internal C6F6. Table 1
shows selected 19F NMR signals of reported compounds. All
measurements were performed at 22 °C in CDCl3 unless stated
otherwise. The second-order coupling constants were deduced using
the gNMR simulation program. Table 2 shows crystal structure
information for complexes 2a and 7a. Elemental analyses were
performed in the laboratory for microanalysis at the Hebrew
University of Jerusalem.
2
2
2
b w )1/[σ2(Fo ) + (0.0302P)2 + 3.2056P], where P ) (Fo + 2Fc )/3.
Observations of 3 and 3′. 3a: A solution of 1a (0.02 mmol) in
C6H6 (2 mL) was treated with AgF (0.03 mmol). The resulting
suspension was stirred vigorously for 15 h. Further stirring led to
the corresponding difluoride complex. The C6H6 was concentrated,
and 3 mL of hexane was added resulting in product precipitation
as a yellow powder (95% pure by NMR). 31P{1H}: 13.61 (d, JFP
) 19.1 Hz, JPtP ) 2747.1 Hz). 19F{1H}: -310.38 (t, JPtF ) 543.1
Hz). Addition of 1 equiv of (CH3)3SiI to a solution of 2a in CH2-
Cl2 or NMP resulted in the formation of 3′, together with 1a and
the unreacted 2a. 3′: 31P{1H} 11.88 (overlapped), 1.95 (dd, JPaPb
) 13.8 Hz, JF(trans)Pb ) 181.9 Hz, JPtPb ) 2991.0 Hz); 19F{1H}
-246.99 (dd, JF(cis)P ) 28.6 Hz, JPtF ) 68.8 Hz).
Synthesis of 2. In a typical procedure, 1a or 1b (0.02 mmol) in
2 mL of CH2Cl2 was vigorously stirred with 8 mg (0.063 mmol)
of AgF for 3 h. The suspension was filtered through a cotton pad
and Celite, the filtrate was concentrated in a vacuum, and 3 mL of
hexane was added. The resulting white precipitate was collected
and dried in a vacuum. Yield: 90-95%. In the case of 1c, 10 equiv
of AgF were used and the suspension was stirred for 2 days. After
filtration, the solvent was evaporated and the product extracted with
hexane (ca. 85% pure by NMR).
3b: A solution of 1b (0.02 mmol) in CH2Cl2 (2 mL) was treated
with AgF (0.02 mmol). The resulting suspension was vigorously
stirred for 30 min resulting in a mixture of 2b (30%) and 3b (70%).
31P{1H}: 12.07 (d, JFP ) 18.6 Hz, JPtP ) 2473.8 Hz). 19F{1H}:
-335.20 (t, JPtF ) 494.4 Hz). Warming this mixture in NMP at 45
°C for 5 h showed complete conversion of 3b into the 3′. 31P{1H}:
16.93 (m, JPtPa ) 3501.8 Hz), -1.47 (dd, JPtPb ) 4469.9 Hz, JPaPb
2a: 31P{1H} 5.03 (AA′MXX′, ∼30%, JF(trans)P ) 180.0 Hz, JPtP
) 14.9 Hz, JF(trans)Pb ) 166.9 Hz). 19F{1H}: -248.10 (dd, JF(cis)P
22.3 Hz). 3′ was also observed in the reaction mixture upon addition
of 1 equiv of (CH3)3SiI to a solution of 2b in CH2Cl2 or NMP.
)
) 3966.4 Hz, JP(cis)P ) 21.0 Hz); 19F{1H} -216.34 (A ) A′MXX′,
1
JPtF ) 108.0 Hz, JP(cis)F ) 18.0 Hz, JF(cis)F ) 88.0 Hz); H 6.92-
7.49 (m, Ar-H); FAB-MS M+ (M+ calcd for C36H30F2P2Pt): m/z
757 (m/z 757). Anal. Found (calcd) for C36H30F2P2Pt: C, 56.26
(57.07); H, 4.46 (3.99).
3c: A solution of 1c (0.03 mmol) in CH2Cl2 (2 mL) was treated
with AgF (0.06 mmol). The resulting suspension was stirred
vigorously for 4 h and filtered. The CH2Cl2 solution was concen-
trated, and 3 mL of hexane was added resulting in the product
precipitating as a yellow powder (95% pure by NMR). 31P{1H}:
31.09 (d, JPF ) 12.6 Hz, JPtP ) 2485.3 Hz). 19F{1H}: -329.68 (t,
2b: 31P{1H} 3.18 (AA′MXX′, ∼30%, JF(trans)P ) 181.0 Hz, JPtP
1
) 3748.1 Hz); 19F{1H} -225.31 (AA′MXX′); H 1.20 (m, CH3,
18H), 1.86 (m, CH2, 12H); 13C{1H} 7.85 (s, CH3), 15.08 (br s,
CH2). Anal. Found (calcd) for C12H30F2P2Pt: C, 30.75 (30.71); H,
6.71 (6.44).
1
JPtF ) 520.6 Hz). H NMR: 1.38 (m, CH3, 36H), 2.88 (m, C-H,
6H). FAB-MS M+ (M+ calcd for C18H42FIPt): m/z 661 (m/z 661).
2c: 31P{1H} 34.87 (t, JFP ) 11.2 Hz, JPtP ) 2822.4 Hz); 19F-
{1H} -455.90 (t, JPtF ) 973.6 Hz). FAB-MS M+ (M+ calcd for
C18H42F2P2Pt): m/z 553 (m/z 553).
Synthesis of 7a-d. In a typical procedure, a cold (-30 °C)
freshly prepared solution of XeF2 (0.034 mmol in 1 mL) was
quickly added to a solution of 1 (0.034 mmol) in CH2Cl2 (1 mL)
1552 Inorganic Chemistry, Vol. 44, No. 5, 2005

Difluoro Complexes of Platinum(II) and -(IV)
at -30 °C. The reaction mixture was left at this temperature for
10 min and then slowly warmed to room temperature. The 31P-
{1H} NMR spectrum showed the disappearance of the starting
material and formation of the corresponding difluoride complex.
The CH2Cl2 was concentrated, and 3 mL of hexane was added
resulting in the product precipitating as white powder in high yields
(92-97%). 7d was too soluble in hexane to be isolated by
precipitation and purified. The XeF2 solution must be reacted within
15-30 min of preparation to avoid the formation of side products.
7a: 31P{1H} 8.30 (t, JFP ) 23.6 Hz, JPtP ) 2130.4 Hz); 19F{1H}
-252.49 (br s, 2F) which appears as triplet in NMP (JPtF ) 104.2
Observations of 9b,c. To a solution of 7b,c in NMP or CH2Cl2
(1 mL) was added 1 equiv of (CH3)3SiCl. Complexes 9b,c were
observed in the mixture with 8b,c and unreacted 7b,c.
9b (NMP): 31P{1H} 3.39 (d, JFP ) 19.9 Hz, JPtP ) 1939.0 Hz);
19F{1H} -280.31 (m, Pt-F, 1F), -121.93 (s, Ar-F, 1F), 121.86
(s, Ar-F, 1F).
9c (CH2Cl2): 31P{1H} 0.77 (d, JFP ) 22.2 Hz, JPtP ) 1832.3
Hz); 19F{1H} -281.92 (br s, Pt-F, 1F), -120.99 (s, Ar-F, 1F),
120.22 (s, Ar-F, 1F).
Synthesis of 10b,c. To a 9:1 toluene-NMP solution of 7b (20
mg, 0.02 mmol in 1 mL) was added 4 µL (0.022 mmol) of (CH3)3-
SiOTf. The 19F{1H} NMR spectrum revealed the formation of 1
equiv of (CH3)3SiF and 10b. The latter was isolated as a white
solid in 80% yield by concentration in a vacuum and addition of 3
mL of hexane. Under similar conditions, 10c was also prepared in
solution; however, we could not isolate it in pure form.
10b: 31P{1H} 4.27 (s, JFP ) 18.8 Hz, JPtP ) 1987.4 Hz); 19F-
{1H} -274.52 (m, Pt-F, 1F), which appears as triplet in NMP
(JPtF ) 97.0 Hz), -118.70 (s, Ar-F, 1F), -118.04 (s, Ar-F, 1F),
-80.36 (s, CF3, 3F); 1H NMR 7.06 (br s, Ar-H, 4H), 7.14 (br t, J
) 7.4 Hz Ar-H, 4H), 7.20-7.62 (m, Ar-H, 30H); FAB-MS M+
(M+ calcd for C49H38F6O3SPt): m/z 1075 (m/z 1075).
1
Hz); H 6.32 (m, Ar-H), 6.73 (m, Ar-H), 6.77-7.74 (m, Ar-H).
Anal. Found (calcd) for C48H40F2P2Pt: C, 62.20 (63.20); H, 4.63
(4.42).
7b: 31P{1H} 8.32 (t, JFP ) 21.5 Hz, JPtP ) 2070.4 Hz); 19F{1H}
-255.22 (br s, 2F) which appears as triplet in NMP (JPtF ) 122.3
Hz), -119.83 (s, Ar-F, 2F); 1H 6.14 (br t, J ) 8.7 Hz, Ar-H, 4H),
6.89 (br s, 4H), 7.04-7.43 (m, 30H); 13C{1H} 112.73 (m, Pt-Ar),
126.43 (m, Ar), 128.17 (t, J ) 5.5 Hz, Ar), 131.02 (s, Ar), 134.84
(m, Ar), 135.55 (br s, Ar), 137.21 (br s, Ar), 161.10 (br d, F-Ar,
JF-C ) 242.2 Hz). Anal. Found (calcd) for C48H38F4P2Pt: C, 61.63
(60.82); H, 4.39 (4.04).
10c: 31P{1H} 12.87 (d, JFP ) 20.2 Hz, JPtP ) 1808.5 Hz); 19F-
7c: 31P{1H} 7.03 (t, JFP ) 21.6 Hz, JPtP ) 1877.7 Hz); 19F{1H}
{1H} -263.81 (t, Pt-F, 1F, JPtF ) 75.9 Hz in toluene), -117.69
-270.89 (br-s, Pt-F, 2F) which appears as triplet in NMP (JPtF
)
1
1
(s, Ar-F, 1F), -116.93 (s, Ar-F, 1F), -77.45 (br s, CF3, 3F); H
104.3 Hz), -119.71 (s, Ar-F, 2F); H NMR 0.79 (m, CH3, 18H),
1.68 (m, CH2, 12H), 6.91 (br t, J ) 8.6 Hz, Ar-H, 4H), 7.76 (br s,
Ar-H, 4H); 13C{1H} 7.66 (s, CH3), 12.48 (m, CH2), 114.57 (m,
Pt-Ar), 116.39 (m, Ar), 136.95 (br s, Ar), 162.24 (d, F-C, JF-C
) 242.6 Hz). Anal. Found (calcd) for C24H38F4P2Pt‚0.2CH2Cl2: C,
42.84 (42.61); H, 5.73 (5.66).
NMR 0.55 (m, CH3, 18H), 1.69 (br m, CH2, 12H), 6.68 (br t, Ar-
H, 4H, JHH ) 8.4 Hz), 6.79-7.61 (m, Ar-H, 4H); FAB-MS M+
(M+ calcd for C25H38F6O3SPt): m/z 789 (m/z 789).
Reductive Elimination in 8b. An NMP solution of 8b (20
mg,0.02 mmol) in a sealed NMR tube was warmed at 45 °C in an
oil bath, and the reaction progress was monitored by 19F NMR (C6F6
as a reference). After 5 h, the complete disappearance of 8b was
observed with the concomitant formation of 4,4-difluorobiphenyl.
The 31P NMR spectrum showed the formation of (Ph3P)2PtCl2, 4a,
as the only product.
Exchange Reaction with (p-tolyl)3P. To a solution of 8b in
NMP (10 mg, 0.01 mmol) was added 30 mg (10 equiv) of (p-
tolyl)3P, and the mixture was warmed at 45 °C for 5 h in an NMR
tube. The 31P and 19F NMR spectra showed the disappearance of
8b and formation of the new complex ((p-tolyl)3P)2Pt(p-FC6H4)2-
Cl2. An equivalent amount of free PPh3 was also observed in the
31P NMR spectrum: 31P{1H} 0.93 (s, JPtP ) 1952.4 Hz); 19F{1H}
-120.90 (s, Ar-F, 2F).
7d: 31P{1H} 14.27 (t, JFP ) 17.8 Hz, JPtP ) 1762.5 Hz); 19F-
{1H} -261.03 (br s, Pt-F, 2F), -120.74 (s, Ar-F, 2F).
Synthesis of 8b,c. A solution of 0.02 mmol of 7b,c in 1 mL of
CH2Cl2 was treated with 2 equiv of (CH3)3SiCl. The 31P{1H} and
19F{1H} NMR spectra indicated the disappearance of the starting
material and formation of the corresponding dichloride complex.
The CH2Cl2 was concentrated, and 3 mL of hexane was added
resulting in product precipitation as a white powder (90-94%
isolated yields).
1
8a: 31P{1H} 1.94 (s, JPtP ) 2014.7 Hz); H NMR 6.33-7.74
(m, Ar-H); 13C{1H} 114.53 (m, Pt-Ar), 127.56 (br s, Ar), 128.28
(m, Ar), 129.31 (br s, Ar), 130.94 (br s, Ar) 134.83 (br s, Ar), 135.29
(m, Ar) 139.49 (br s, Ar).
8b: 31P{1H} 1.59 (s, JPtP ) 1966.1 Hz); 19F{1H} -121.03 (s,
Acknowledgment. This work was supported by a Tel
Aviv University Internal Grant. A.V. is the incumbent of
the Raymond and Beverly Sackler Career Development Chair
and the Yigal Alon Fellow. The authors thank Prof. David
Milstein for valuable discussions and Prof. Yoram Cohen
for performing the gNMR calculations.
1
Ar-F, 2F); H NMR 6.15 (br s, Ar-H, 4H), 7.00-7.50 (m, Ar-H,
34H); 13C{1H} 112.79 (m, Pt-Ar), 127.65 (t, J ) 5.5 Hz, Ar),
128.03 (m, Ar), 130.76 (br s, Ar), 134.99 (br m, Ar) 135.85 (br s,
Ar), 140.19 (br s, Ar). Anal. Found (calcd) for C48H38Cl2F2P2Pt:
C, 58.45 (58.78); H, 4.19 (3.91).
8c: 31P{1H} -3.91 (s, JPtP ) 1784.1 Hz); 19F{1H} -120.33 (s,
Ar-F, 2F); 1H NMR 0.94 (m, CH3, 18H), 1.98 (m, CH2, 12H), 6.75
(br t, J ) 8.5 Hz, Ar-H, 4H), 7.24 (br s, Ar-H, 4H); 13C{1H} 8.54
(s, CH3), 14.24 (m, CH2), 114.26 (m, Pt-Ar), 122.65 (br s, Ar),
138.87 (br s, Ar), 161.41 (d, F-Ar, JFC ) 244.5 Hz). Anal. Found
(calcd) for C24H38Cl2F2P2Pt: C, 41.90 (41.63); H, 5.65 (5.53).
Supporting Information Available: X-ray crystallographic files
(CIF) for 2a and 7a and NMR spectra of complexes 2a and 7a.
This material is available free of charge via the Internet at
http://pubs.acs.org.
IC0488177
Inorganic Chemistry, Vol. 44, No. 5, 2005 1553