Platinum(II) phosphido complexes as metalloligands. Structural and spectroscopic consequences of conversion from terminal to bridging coordination

Article abstract of DOI:10.1021/om050149p

Treatment of the terminal phosphido complexes Pt(dppe)(Me)(PPh(R)) (R = Ph (1), i-Bu (6)) with Pt(dppe)(Me)(OTf) gave the cationic μ-phosphido complexes [(Pt(dppe)(Me))₂(μ-PPh(R))][OTf] (R = Ph (7), i-Bu (8)). Similarly, Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10) was converted to [(Pt((R,R)-Me-Duphos)(Me))₂(μ-PPh(i-Bu))][OTf] (11). A fluxional process in 8 and 11, presumably involving hindered rotation about the Pt-PPh(i-Bu) bonds, was observed by NMR spectroscopy; it resulted in two diastereomers for 8 and four for 11 at low temperature. Coordination of the metalloligand 10 to the [Pt((R,R)-Me-Duphos)(Me)]⁺ fragment, yielding 11, resulted in structural changes at the Pt-phosphido group, whose geometry changed from distorted pyramidal to tetrahedral. Decomposition of 6 also gave the cation 8, while oxidation of 6 with H₂O₂ gave the crystallographically characterized phosphido oxide complex Pt(dppe)(Me)(P(O) Ph(i-Bu)) (12).

Full text of DOI:10.1021/om050149p

3370
Organometallics 2006, 25, 3370-3378
Platinum(II) Phosphido Complexes as Metalloligands. Structural
and Spectroscopic Consequences of Conversion from Terminal to
Bridging Coordination
Corina Scriban,† Denyce K. Wicht,†,‡ David S. Glueck,*,† Lev N. Zakharov,§
James A. Golen,§ and Arnold L. Rheingold§
6128 Burke Laboratory, Department of Chemistry, Dartmouth College, HanoVer, New Hampshire 03755,
and Department of Chemistry and Biochemistry, UniVersity of California, San Diego, 9500 Gilman DriVe,
La Jolla, California 92093
ReceiVed March 2, 2005
Treatment of the terminal phosphido complexes Pt(dppe)(Me)(PPh(R)) (R ) Ph (1), i-Bu (6)) with
Pt(dppe)(Me)(OTf) gave the cationic µ-phosphido complexes [(Pt(dppe)(Me))2(µ-PPh(R))][OTf] (R )
Ph (7), i-Bu (8)). Similarly, Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10) was converted to [(Pt((R,R)-Me-
Duphos)(Me))2(µ-PPh(i-Bu))][OTf] (11). A fluxional process in 8 and 11, presumably involving hindered
rotation about the Pt-PPh(i-Bu) bonds, was observed by NMR spectroscopy; it resulted in two
diastereomers for 8 and four for 11 at low temperature. Coordination of the metalloligand 10 to the
[Pt((R,R)-Me-Duphos)(Me)]+ fragment, yielding 11, resulted in structural changes at the Pt-phosphido
group, whose geometry changed from distorted pyramidal to tetrahedral. Decomposition of 6 also gave
the cation 8, while oxidation of 6 with H2O2 gave the crystallographically characterized phosphido oxide
complex Pt(dppe)(Me)(P(O)Ph(i-Bu)) (12).
Chart 1. Pt(II) Terminal Phosphido Complexes 1-4 and
Dinuclear µ-Phosphido Complex 5 Formed When 3 Acts as
a Ligand3
Introduction
Forty years ago, Chatt and Davidson considered the possibility
of terminal Pt-PPh2 ligands: “it seems unlikely that they can
exist in the Pt(II) series except under very special circumstances,
the tendency to occupy bridging positions between Pt atoms
being too strong.”1 Avoiding labile ligands such as halides and
monodentate phosphines is one way to fulfill the required special
circumstances and prepare stable Pt(II) terminal phosphido
complexes, such as the ones shown in Chart 1.2
* To whom correspondence should be addressed. E-mail: glueck@
dartmouth.edu.
† Dartmouth College.
‡ Present address: Department of Chemistry, Suffolk University, Boston,
Massachusetts 02108.
§ University of California, San Diego.
(1) Chatt, J.; Davidson, J. M. J. Chem. Soc. 1964, 2433-2445.
(2) For other terminal Pt-phosphido complexes, see: (a) Allen, C. W.;
Ebsworth, E. A. V.; Henderson, S. G.; Rankin, D. W. H.; Robertson, H.
E.; Turner, B.; Whitelock, J. D. J. Chem. Soc., Dalton Trans. 1986, 1333-
1338. (b) Schaefer, H.; Binder, D. Z. Anorg. Allg. Chem. 1988, 560, 65-
79. (c) Mastrorilli, P.; Nobile, C. F.; Fanizzi, F. P.; Latronico, M.; Hu, C.;
Englert, U. Eur. J. Inorg. Chem. 2002, 1210-1218. (d) Zhuravel, M. A.;
Glueck, D. S.; Zakharov, L. N.; Rheingold, A. L. Organometallics 2002,
21, 3208-3214. (e) Kovacik, I.; Wicht, D. K.; Grewal, N. S.; Glueck, D.
S.; Incarvito, C. D.; Guzei, I. A.; Rheingold, A. L. Organometallics 2000,
19, 950-953. (f) Wicht, D. K.; Kourkine, I. V.; Kovacik, I.; Glueck, D. S.;
Concolino, T. E.; Yap, G. P. A.; Incarvito, C. D.; Rheingold, A. L.
Organometallics 1999, 18, 5381-5394. (g) Wicht, D. K.; Glueck, D. S.;
Liable-Sands, L. M.; Rheingold, A. L. Organometallics 1999, 18, 5130-
5140. (h) Wicht, D. K.; Kovacik, I.; Glueck, D. S.; Liable-Sands, L. M.;
Incarvito, C. D.; Rheingold, A. L. Organometallics 1999, 18, 5141-5151.
(i) Kourkine, I. V.; Sargent, M. D.; Glueck, D. S. Organometallics 1998,
17, 125-127. (j) Wicht, D. K.; Kourkine, I. V.; Lew, B. M.; Nthenge, J.
M.; Glueck, D. S. J. Am. Chem. Soc. 1997, 119, 5039-5040. (k) David,
M.-A.; Wicht, D. K.; Glueck, D. S.; Yap, G. P. A.; Liable-Sands, L. M.;
Rheingold, A. L. Organometallics 1997, 16, 4768-4770. (l) David, M.-
A.; Glueck, D. S.; Yap, G. P. A.; Rheingold, A. L. Organometallics 1995,
14, 4040-4042. (m) Scriban, C.; Glueck, D. S. J. Am. Chem. Soc. 2006,
128, 2788-2789. For a Pt-phosphenium complex, see: (n) Hardman, N.
J.; Abrams, M. B.; Pribisko, M. A.; Gilbert, T. M.; Martin, R. L.; Kubas,
G. J.; Baker, R. T. Angew. Chem., Int. Ed. 2004, 43, 1955-1958.
Such metal phosphido complexes contain pyramidal, nucleo-
philic phosphorus centers, which can act as ligands to other
metals.4 For example, the reaction of 3 with [Pt(NCN)(H2O)]+
(NCN ) 2,6-(CH2NMe2)2C6H3) gave the bimetallic complex
5.3c We report here that Pt phosphido compounds such as 1
can also be converted into analogous µ-phosphido complexes,
and we describe the spectroscopic and structural consequences
of this change in coordination mode.
(3) For 1, see: (a) Wicht, D. K.; Paisner, S. N.; Lew, B. M.; Glueck, D.
S.; Yap, G. P. A.; Liable-Sands, L. M.; Rheingold, A. L.; Haar, C. M.;
Nolan, S. P. Organometallics 1998, 17, 652-660. For 2, see: (b) Handler,
A.; Peringer, P.; Muller, E. P. J. Chem. Soc., Dalton Trans. 1990, 3725-
3727. For 3 and 5, see: (c) Maassarani, F.; Davidson, M. F.; Wehman-
Ooyevaar, I. C. M.; Grove, D. M.; van Koten, M. A.; Smeets, W. J. J.;
Spek, A. L.; van Koten, G. Inorg. Chim. Acta 1995, 235, 327-338. For 4,
see: (d) Cecconi, F.; Ghilardi, C. A.; Midollini, S.; Moneti, S.; Orlandini,
A.; Scapacci, G. Inorg. Chim. Acta 1991, 189, 105-110.
10.1021/om050149p CCC: $33.50 © 2006 American Chemical Society
Publication on Web 06/09/2006

Pt(II) Phosphido Complexes as Metalloligands
Organometallics, Vol. 25, No. 14, 2006 3371
Table 1. Variable-Temperature 31P NMR Data (toluene-d8)
for Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10)a
Scheme 1
q
resonance
δ (ppm)
∆ν (Hz)
Tc (K)
∆Gc
trans Duphos P
PPh(i-Bu)
69.6, 67.8
-57.3, -63.9
809
1350
283
313
12.8
13.4
a Chemical shifts and ∆ν values were obtained from slow-exchange
spectra at -60 °C. Estimated errors are different for each resonance;
q
“typical” errors are 5 Hz in ∆ν, 10 °C in Tc, and 0.5 kcal/mol in ∆Gc .
Scheme 3a
Scheme 2
a [Pt] ) Pt((R,R)-Me-Duphos.
agreement between the data obtained for the two groups at
different coalescence temperatures. The barrier to the dynamic
process (a combination of P inversion and rotation about the
Pt-P bond) of ca. 13 kcal/mol was similar to those we reported
earlier for structurally analogous Pt-phosphido complexes.2d,g,h
As in the synthesis of phosphido-bridged complexes 7 and
8, treatment of 9 with AgOTf, followed by reaction with 10,
gave [(Pt((R,R)-Me-Duphos)(Me))2(µ-PPh(i-Bu))][OTf] (11) as
a white solid which was soluble in polar solvents (Scheme 3).
NMR spectroscopy provided information on the structure and
dynamics of the µ-phosphido complexes. Restricted rotation
about the Pt-P bonds in complex 5 was proposed to account
for its fluxionality.3c Similar processes are possible for 7, 8,
and 11. In the highest-symmetry complex, 7, the bulky Pt(dppe)-
(Me) groups would be equivalent in conformations where they
could be related by a C2 axis (A) and/or a mirror plane
containing the PPh2 group (B). This would result in an AA′BB′X
spin system for the isotopologue of 7 containing no 195Pt atoms,
along with AA′BB′XM and AA′BB′XMM′ spin systems for the
other isotopologues.11
Because the unsymmetrical substitution of the phosphido
group in 8 destroys the C2 axis (A above), its Pt(dppe)(Me)
groups can be equivalent only if they are related by a mirror
plane (B) containing the PPh group and bisecting the P-CH2-
CHMe2 moiety. This would give rise to spin systems such as
those described above for 7. However, if such a conformation
is not accessible, the Pt(dppe)(Me) groups would be inequiva-
lent, resulting in ABCDX and ABCDXMN spin systems for
the isotopologues containing zero and two 195Pt atoms. If the
Pt nuclei are inequivalent, the isotopologues with one 195Pt
(ABCDXM spin systems) are different compounds, which
should give rise to distinct 31P NMR spectra. Finally, the
chirality of (R,R)-Me-Duphos in 11 means that a potential mirror
plane (B) cannot relate the Pt((R,R)-Me-Duphos)(Me) groups;
therefore, this complex must display the reduced symmetry
(ABCDX, etc.) described above.
Results and Discussion
Synthesis of µ-Phosphido Complexes. In analogy to the
formation of 5 from 3, treatment of the terminal phosphido
complexes 1 and Pt(dppe)(Me)(PPh(i-Bu)) (6)3a with Pt(dppe)-
(Me)(OTf),5 generated from Pt(dppe)(Me)(Cl)6 and AgOTf, gave
the µ-phosphido complexes [(Pt(dppe)(Me))2(µ-PPh(R))][OTf]
(R ) Ph (7), i-Bu (8); Scheme 1).
Analogous chiral µ-phosphido complexes were prepared using
(R,R)-Me-Duphos instead of dppe. Treatment of Pt(COD)(Me)-
(Cl)7 with (R,R)-Me-Duphos gave Pt((R,R)-Me-Duphos)(Me)-
(Cl) (9),8 which was converted to the terminal phosphido
complex Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10) by reaction
with PHPh(i-Bu) in the presence of NaOSiMe3 (Scheme 2).
The room-temperature NMR spectra of 10 were very broad,
but at -40 °C, P inversion became slow on the NMR time scale
and the expected two diastereomers could be observed, in a
1:1.2 ratio.9 Measurement of the 31P NMR coalescence tem-
peratures for the phosphido P and the Duphos P trans to it (the
cis Duphos P signal occurred at the same chemical shift for
both diastereomers) provided the approximate free energy of
activation for the fluxional process (Table 1),10 with reasonable
(4) For some examples, see: (a) Carty, A. J.; MacLaughlin, S. A.;
Nucciarone, D. In Phosphorus-31 NMR Spectroscopy in Stereochemical
Analysis; Verkade, J. G., Quin, L. D., Eds.; VCH: Deerfield Beach, FL,
1987; pp 559-619. (b) Stephan, D. W. Coord. Chem. ReV. 1989, 95, 41-
107. (c) Baker, R. T.; Tulip, T. H.; Wreford, S. S. Inorg. Chem. 1985, 24,
1379-1383. (d) Barre, C.; Boudot, P.; Kubicki, M. M.; Moise, C. Inorg.
Chem. 1995, 34, 284-291.
(5) Hill, G. S.; Yap, G. P. A.; Puddephatt, R. J. Organometallics 1999,
18, 1408-1418.
(6) Appleton, T. G.; Bennett, M. A.; Tomkins, I. B. J. Chem. Soc., Dalton
Trans. 1976, 439-446.
The experimental NMR spectra were consistent with these
(7) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411-
1
predictions. For µ-PPh2 complex 7, 31P and H NMR spectra
428.
(8) For the analogous Pd complex, see: Murtuza, S.; Harkins, S. B.;
Sen, A. Macromolecules 1999, 32, 8697-8702.
(11) The spin system for the isotopologue with no 195Pt could simplify
to A2B2X if the dppe P nuclei are not magnetically inequivalent (for
example, if the cis JPP(dppe) value is 0). For the isotopologue with one
195Pt, we assume that isotopic substitution does not change the 31P NMR
chemical shifts.
(9) Rogers, J. R.; Wagner, T. P. S.; Marynick, D. S. Inorg. Chem. 1994,
33, 3104-3110.
(10) Friebolin, H. Basic One- and Two-Dimensional NMR Spectroscopy,
2nd ed.; VCH: New York, 1993; pp 287-314.

3372 Organometallics, Vol. 25, No. 14, 2006
Scriban et al.
Table 2. 31P{1H} NMR Data for the Dinuclear Complexes [(Pt(diphos)(Me))2(µ-PPh(R))][OTf] (7, 8, and 11)a
δ (JPt-P
)
diphos, R (no.)
temp (°C)
P1
P4
P2
P5
P3
J23, J53
J13, J43
dppe, Ph (7)b
21
21
49.2 (1895)
48.5 (1906)
48.6 (1886)
48.7 (1889)
49.1 (1903)
48.3 (1871)
69.3 (1840)
h
49.2 (1895)
47.6 (1800)
47.2 (1863)
47.0 (1864)
47.4 (1883)
48.3 (1871)
65.2 (1750)
h
52.3 (2450)
52.8 (2338)
53.2d (2330)
53.5 (2331)
53.9 (2331)
51.7 (2382)
67.5 (2292)
h
52.3 (2450)
50.5 (2408)
50.4e (2405)
50.4 (2405)
50.7 (2405)
51.7 (2382)
h
26.8 (2313)
1.0 (2289)
0.8 (2243, 2319)
0.9 (2231, 2319)
1.2f
2.3 (2280)
5.5 (2246)
-7.1 (2307)
-2.1
341
16
15, 15
15, 15
15, 15
f
15
h
dppe, i-Bu (8)c
329, 352
337, 339
334, 340
334, 340
338
334
304
340, 335
-20
-40f
-40f
100g
21h
Me-Duphos, i-Bu (11)
h
h
100i
66.6 (1834)
65.6 (1801)
65.9 (2325)
65.8 (2330)
a Chemical shift standard: external 85% H3PO4. Chemical shifts are given in ppm and coupling constants in Hz. Solvent: CD2Cl2 unless otherwise
indicated. b Additional couplings for 7: J14 ) 12, J25 ) 5, J46 ) J17 ) 37. c The signals were very broad; therefore, the expected two JPt-P couplings for
P3 were not resolved. Although two different JP-P(trans) couplings were observed from the dppe signals, the large line width means they are not significantly
d
e
different. J12 ) 6. J45 ) 4. f Two diastereomers (7:1 ratio). Data for the major isomer are reported first. The breadth and lower intensity of the minor
isomer signals prevented observation of the cis P-P couplings or JPt-P for the µ-PR2 peak. g In DMSO-d6. h Two diastereomers (2.5:1 ratio). Data for the
major isomer are reported first. The signals were broad; only the µ-phosphido peak for the minor diastereomer b and one of the two expected trans Duphos
signals for the major isomer a could be observed. i In 1,2-CD2Cl4; the peaks (especially the µ-phosphido signal) were broad.
Figure 1. The µ-phosphido portion of the experimental (top) and simulated13 (bottom) 31P{1H} NMR spectra of [(Pt(dppe)(Me))2(µ-PPh-
(i-Bu))][OTf] (8) in CD2Cl2 at -20 °C.
indicated equivalent Pt(dppe)(Me) groups, even at low temper-
ature. The 31P NMR spectrum could be simulated with the
parameters in Table 2 for the spin systems described above.12,13
The 31P NMR spectrum of the µ-PPh(i-Bu) complex 8 was
broadened at room temperature in CD2Cl2, but at -20 °C, sharp
signals for the four different dppe P nuclei could be observed,
consistent with inequivalent Pt(dppe)(Me) groups (Table 2). The
µ-phosphido signal had an unusual appearance (Figure 1), since
it showed two different large trans JPP couplings (339 and 337
Hz) and two cis JPP couplings of the same magnitude (15 Hz).
Therefore, the central peak, which results from molecules which
contain no 195Pt, appeared as an overlapping doublet of doublets
of triplets.
distinct from that of the central signal, which is different from
the usual observations in symmetrical dinuclear µ-phosphido
complexes.14 A second set of low-intensity satellite signals arises
from the isotopologue which contains two 195Pt nuclei. The 1H-
{31P} NMR spectrum of 8 at 25 °C showed only broad signals,
but the resonances were much sharper at -60 °C, and two
different Pt-Me signals were observed at δ 1.22 (JPt-H ) 63
Hz) and δ 0.81 (JPt-H ) 60 Hz), again consistent with
inequivalent Pt(dppe)(Me) groups.
At high temperature (100 °C in DMSO-d6), the four different
dppe 31P NMR signals coalesced into two, and one Pt-Me peak
1
(δ 1.02 (d, J ) 7, JPt-H ) 63 Hz)) was observed by H NMR
spectroscopy. The resulting spectra were similar to those of the
µ-PPh2 complex 7 and consistent with the equivalence of the
Pt(dppe)(Me) groups on the NMR time scale at high temper-
ature, due to the conformational changes discussed above.
When a CD2Cl2 solution of 8 was cooled further (to -40
°C), NMR signals due to the two diastereomers a and b (7:1
ratio), which presumably result from compounds differing in
the relative conformations of the Pt(dppe)(Me) groups, were
The two different Pt-P couplings to the µ-PR2 group (2243
and 2319 Hz) can be seen most clearly in the major Pt satellite
peaks, which are a superposition of subspectra of the two
different isotopologues which contain one 195Pt (ABCDXM spin
systems). This effect explains why these peaks show a pattern
(12) Abraham, R. J. The Analysis of High-Resolution NMR Spectra;
Elsevier: Amsterdam, 1971.
(13) Simulation with gNMR: Budzelaar, P. H. M. gNMR; Cherwell
Scientific, 1992-1996.
(14) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of Transition Metal
Phosphine Complexes; Springer-Verlag: New York, 1979.

Pt(II) Phosphido Complexes as Metalloligands
Organometallics, Vol. 25, No. 14, 2006 3373
Table 3. Selected 31P NMR Data for Terminal and Bridging Phosphido Groups in the Complexes Pt(diphos)(Me)(PPh(R)) and
[(Pt(diphos)(Me))2(µ-PPh(R))][OTf]a
complex
Pt(dppe)(Me)(PPh2) (1)
δ(PR2)
JPP(trans)
JPt-P(PR2)
JPt-P(trans to PR2)
-7.8
26.8
144
341
134
337, 339
129
130
334
304
1039
2313
946
2243, 2319
999
1011
2246
2307
1932
2450
1805
2330, 2405
1808
[(Pt(dppe)(Me))2(µ-PPh2)][OTf] (7)
Pt(dppe)(Me)(PPh(i-Bu)) (6)
-29.9
[(Pt(dppe)(Me))2(µ-PPh(i-Bu))][OTf] (8)b
Pt(Me-Duphos)(Me)(PPh(i-Bu)) (10)c
0.8
-57.3
-63.9
5.5
1816
[(Pt(Me-Duphos)(Me))2(µ-PPh(i-Bu))][OTf] (11)d
2292 (broad)e
-7.1
a Chemical shift standard: external 85% H3PO4. Chemical shifts are given in ppm and coupling constants in Hz. Solvent: C6D6 for 1 and 6, toluene-d8
for 10, CD2Cl2 for 7, 8, and 11. Data for 1 and 6 are from ref 3a. b At -20 °C. c At -40 °C, two diastereomers. d At 21 °C, two diastereomers. e The expected
two different Me-Duphos signals could not be resolved.
observed. The 31P NMR data for these species were similar to
those observed at higher temperature (Table 2).
Two diastereomers of 11 were also observed, but at room
temperature. Again, we presume that these differ in the relative
positions of the (Pt((R,R)-Me-Duphos)(Me)) moieties. The
µ-phosphido signals, as in 8, should show two different Pt-P
couplings, but these peaks were simply broad triplets with only
one JPt-P apparent. At 100 °C in CD2Cl4, the 31P NMR spectrum
of 11 showed broad peaks apparently due to a single species,
perhaps because rotation about the Pt-P bonds was no longer
slow on the NMR time scale. As expected, the four Me-Duphos
P nuclei remained inequivalent at this temperature.15 At -60
°C in CD2Cl2, four diastereomers were observed (see the
Experimental Section); these formed two sets of isomers with
similar µ-phosphido 31P NMR chemical shifts (δ 2.9 and 2.6
vs δ -10.1 and -10.3).
From Terminal to Bridging Phosphido Ligands: Spec-
troscopic and Structural Consequences. The 31P NMR data
for the terminal and bridging phosphido complexes (Table 3)
provided information on the changes in structure and bonding
that result from the change in coordination mode. In addition
to a substantial coordination chemical shift, both JPP (trans) and
JPt-P for the phosphido group increased significantly on quat-
ernization. The small magnitudes of these couplings in terminal
Pt-phosphido complexes have been ascribed to low s character
in the Pt-P bonds, so that the lone pair in the pyramidal
phosphido group has increased s character.3a Increased s
character in the Pt-P bond as a result of the change in
coordination number at P would rationalize the observed changes
in these coupling constants; similar effects were seen on
protonation of terminal phosphido complexes.3a Finally, the JPt-P
value for the phosphine trans to the phosphido group also
increased on coordination, consistent with a reduced trans
influence for the µ-phosphido ligand in comparison to its
terminal precursor.16
Figure 2. ORTEP diagram of Pt((R,R)-Me-Duphos)(Me)(Cl) (9).
The Pt((R,R)-Me-Duphos) complexes 9-11 were character-
ized crystallographically (see Figures 2-4, Tables 4 and 5, and
the Supporting Information), to obtain complementary data on
the structural results of complexation of the metalloligand 10
to the Pt((R,R)-Me-Duphos)(Me) cation.17 Although two dia-
stereomers of 10 were observed by low-temperature 31P NMR
spectroscopy, the crystal studied contained only one, with an R
configuration at the phosphido group. The unit cell of dinuclear
11 contained two independent molecules.
Figure 3. ORTEP diagram of Pt((R,R)-Me-Duphos)(Me)(PPh(i-
Bu)) (10). The i-Bu group was disordered and refined with fixed
geometry. The Pt-Me group (C19) was also disordered over two
positions (48/52), only one of which is shown.
All three complexes adopted slightly distorted square planar
geometries. As expected from the greater trans influence of Me
in comparison to that of Cl, the Pt-P bond in 9 trans to the
methyl group (2.223(5) Å) was longer than that trans to Cl
(2.205(5) Å).16 The Pt-Cl and Pt-P (trans to Cl) bond lengths
in 9 (2.347(9) Å and 2.205(5) Å) were similar to those in Pt-
((R,R)-Me-Duphos)Cl2‚CH2Cl2 (2.3854(12) Å (average) and
2.2183(11) Å, respectively).18 The average JPt-P(Duphos) values
for the two diastereomers of 10 at -40 °C were 1768 Hz (trans
to Me) and 1812 Hz (trans to PPh(i-Bu)). These data predict
(15) Similarly, the menthyl groups in tetrahedral Sn((-)-menthyl)2(Ph)-
(I) were inequivalent: Dakternieks, D.; Dunn, K.; Henry, D. J.; Schiesser,
C. H.; Tiekink, E. R. T. Organometallics 1999, 18, 3342-3347.
(16) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. ReV.
1973, 10, 335-422.
(17) For another example of structural comparisons before and after
conversion of a terminal phosphido ligand to a bridging one, see ref 4c.

3374 Organometallics, Vol. 25, No. 14, 2006
Scriban et al.
Scheme 4a
a [Pt] ) Pt(dppe).
above, as observed in related Pt(diphos) phosphido com-
plexes,2d-h,3a such as Pt((R,R)-Me-Duphos)(PPhIs)(H) (Is )
2,4,6-(i-Pr)3C6H2; Pt-PR2 ) 2.335(5) Å, average Pt-Duphos
) 2.262(5) Å).2e
When the metalloligand 10 was bound to Pt, the Pt-PR2 bond
lengthened slightly (from 2.372(4) to 2.394(6) Å). The sum of
the angles at the phosphido P in 10 was 306.2(11)°; compare
this pyramidal geometry to the ideal values for tetrahedral
(328.5°) or trigonal-planar (360°) coordination or to 270° for
unhybridized phosphorus (with the lone pair in an s orbital and
P p orbitals used to make the P-R and Pt-P bonds). On
coordination, this phosphorus became essentially tetrahedral. For
the two independent molecules of 11, the angles about P3 ranged
from 120.4(7) to 100.8(10)°; the average was 109.5°. This
change in geometry at phosphorus is consistent with the
increased steric demands of the lone pair in the terminal
phosphido complex 1020 and with increased s character in the
Pt-P bonds (P sp3 hybridization), as discussed above in the
context of the 31P NMR data.
Figure 4. ORTEP diagram of [(Pt((R,R)-Me-Duphos)(Me))2(µ-
PPh(i-Bu))][OTf]‚0.5THF (11), showing one of the two dinuclear
cations. The triflate anion and the solvent are omitted for clarity.
Table 4. Crystallographic Data for
Pt((R,R)-Me-Duphos)(Me)(Cl) (9),
Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10),
[(Pt(R,R)-Me-Duphos)(Me))2(µ-PPh(i-Bu))][OTf]‚0.5THF
(11‚0.5THF), and Pt(dppe)(Me)(P(O)Ph(i-Bu))‚H2O (12‚H2O)
9
10
11‚0.5THF
12‚H2O
formula
C19H31Cl-
P2Pt
C29H45P3Pt C51H80F3-
C37H43O2-
O3.50P5Pt2S P3Pt
formula wt
space group
a, Å
b, Å
c, Å
551.92
P43
681.65
P212121
9.7296(6)
15.4985(9)
1383.24
P1
13.001(6)
13.676(7)
807.71
P21/n
9.446(2)
14.982(3)
25.135(6)
90
97.384(4)
90
3527.7(14)
4
10.6441(7)
10.6441(7)
18.9672(19) 19.1019(12) 18.526(9)
90
90
90
2148.9(3)
4
The NMR results also predicted that the terminal phosphido
ligand in 10 would have a greater trans influence than the
bridging ligand in 11.16 However, the appropriate Pt-P(Duphos)
bond lengths in these compounds (2.243(3) and 2.255(6) Å)
were not significantly different; therefore, this effect could not
be confirmed from the crystallographic data. Finally, the relative
conformations of the Pt(diphos)(Me) groups in the solid state
are relevant to the fluxional processes observed in solution,
where these groups could become equivalent when coplanar
(conformation B above). The average dihedral angle between
the two Pt square planes in 11 was 76.4°, comparable to that
observed in 5 (71.1(2)°); both µ-phosphido complexes displayed
restricted rotation about the Pt-µ-PR2 bonds.3c
From Terminal to Bridging Coordination: An Alternative
Route. We also observed formation of 8 via decomposition of
6 (Scheme 4). Yellow solutions of 6 slowly deposited white
solid 8 at room temperature; the reaction was faster on heating.
It was difficult to induce complete conversion to 8, but filtration
enabled separation from 6. Solid 8 formed by this route was
soluble in polar solvents and could be recrystallized from CH2-
Cl2/ether to give a white powder. NMR and mass spectroscopy
confirmed that cation 8 formed, but how did this happen, and
what was the anion X-?
R, deg
90
90
90
2880.5(3)
4
1.572
5.054
100(2)
82.144(7)
71.255(7)
61.738(6)
2747(2)
2
1.672
5.321
100(2)
â, deg
γ, deg
V, Å3
Z
D(calcd), g/cm3
1.706
1.521
4.144
213(2)
µ(MoKR), mm-1 6.801
temp, K
173(2)
diffractometer
Bruker CCD
R(F), %a
8.04
19.25
6.07
14.55
8.09
19.41
3.37
8.50
Rw(F2), %a
2
2
a Quantities minimized are as follows: Rw(F2) ) ∑[w(Fo - Fc )2]/
2
2
∑[(wFo )2]1/2; R ) ∑∆/∑(Fo) (∆ ) |(Fo - Fc)|; w ) 1/[σ2(Fo ) + (aP)2 +
2
bP]; P ) [2Fc + Max(Fo,0)]/3).
Table 5. Selected Bond Lengths (Å) and Angles (deg) for the
Pt((R,R)-Me-Duphos)(Me)(X) Complexes 9, 10, and
11‚0.5THF
10 (X )
PPh(i-Bu))
11b,c (X )
PPh(i-Bu))
9 (X ) Cl)
Pt-P1 (trans to Me)
Pt-P2 (trans to X)
Pt-Me
2.223(5)
2.205(5)
2.264(13)
2.347(9)
88.2(2)
172.0(4)
90.3(4)
96.0(4)
2.273(3)
2.243(3)
2.13(3)a
2.372(4)
86.44(12)
171.0(9)a
90.45(12)
91.6(7)a
2.301(5)
2.255(6)
2.13(2)
2.394(6)
85.8(2)
171.8(6)
102.56(19)
86.9(6)
171.3(2)
84.3(6)
Pt-X
P1-Pt-P2
P1-Pt-Me
P1-Pt-X
P2-Pt-Me
P2-Pt-X
C-Pt-X
We considered several potential pathways for decomposition
of 6 to give 8 (Scheme 5). Most simply, attack of the phosphido
ligand at the Pt center in another molecule of 6 could displace
the anion [PPh(i-Bu)]- and give cation 8. However, neither this
known anion21 nor the secondary phosphine PHPh(i-Bu), which
would form from it on protonation by adventitious acid, were
observed during the decomposition of 6. Alternatively, oxidation
of 6 by traces of oxygen might produce a better leaving group
177.4(4)
85.7(5)
175.71(13)
91.6(7)a
a The Pt-Me group in 10 was disordered over two positions; average
bond lengths and angles are reported. b [Pt((R,R)-Me-Duphos)(Me)]+. There
are two molecules in the unit cell; average bond lengths and angles are
reported. c The average Pt-P3-Pt angle was 109.5(2)°.
that the methyl group has a slightly larger trans influence,
consistent with the Pt-P((R,R)-Me-Duphos) bond lengths
observed in the solid state: 2.273(3) Å (trans to Me) and 2.243-
(3) Å (trans to PPh(i-Bu)).19 The Pt-P(phosphido) bond in 10
(2.372(4) Å) was longer than the Pt-P((R,R)-Me-Duphos) bonds
(18) Wicht, D. K.; Zhuravel, M. A.; Gregush, R. V.; Glueck, D. S.; Guzei,
I. A.; Liable-Sands, L. M.; Rheingold, A. L. Organometallics 1998, 17,
1412-1419.
(19) Appleton, T. G.; Bennett, M. A. Inorg. Chem. 1978, 17, 738-747.
(20) Bonnet, G.; Kubicki, M. M.; Moise, C.; Lazzaroni, R.; Salvadori,
P.; Vitulli, G. Organometallics 1992, 11, 964-967.

Pt(II) Phosphido Complexes as Metalloligands
Organometallics, Vol. 25, No. 14, 2006 3375
Scheme 5. Possible Routes for Formation of Cation 8
from 6a
a [Pt] ) Pt(dppe).
Scheme 6a
a [Pt] ) Pt(dppe).
in the P(O)Ph(i-Bu) ligand, which could again be displaced by
the Pt-PPh(i-Bu) group.
Figure 5. ORTEP diagram of Pt(dppe)(Me)(PPh(i-Bu)O)‚H2O (12‚
H2O). The water molecule and the hydrogen atoms are not shown
(a partial ORTEP diagram which illustrates the hydrogen bonding
is given in the Supporting Information).
We tested the latter hypothesis by preparing the phosphido
oxide complex Pt(dppe)(Me)(P(O)Ph(i-Bu)) (12) by oxidation
of 6 with H2O2 (Scheme 6; it also formed on exposure of 6 to
air).22 The 31P NMR chemical shifts of the dppe and phosphido
oxide P atoms in 12 were similar, but they could be assigned
on the basis of their Pt-P coupling constants. On oxidation of
trans-Pt(PCy2H)2(PCy2)(Cl) to trans-Pt(PCy2H)2(P(O)Cy2)(Cl),
JPt-P for the phosphido ligand changed from 931 to 3078
Hz.2c,22a Similarly, JPt-P for the P(O)Ph(i-Bu) ligand in 12
increased to 3006 Hz from 946 Hz in 6.3a JPt-P for the dppe P
trans to this ligand decreased from 1805 to 1714 Hz, consistent
with a greater trans influence for the phosphido oxide than for
the phosphido ligand.3a,23 The change in trans JPP on oxidation
of 6 to 12 (from 134 to 411 Hz) is consistent with the trend in
JPt-P and increased s character in the Pt-P bond.3a
When 6 and oxide 12 were combined, cation 8 formed slowly,
as it did in the absence of 12. Thus, inadvertent oxidation to
yield 6-O does not appear to promote cation formation as
proposed in Scheme 5.
To further probe the formation of 8 from 6, we studied the
decomposition of 6 under a variety of conditions, including
deliberate addition of air, water, and the secondary phosphine
PHPh(i-Bu). Cation 8 was reproducibly formed in each case,
along with a varied mixture of unidentified phosphorus products,
observed by 31P NMR spectroscopy (see the Experimental
Section). As mentioned above, these did not include the anion
[PPh(i-Bu)]- or PHPh(i-Bu). Other potential products, including
the secondary phosphine oxide PH(O)Ph(i-Bu), its anion [P(O)-
Ph(i-Bu)]-, commercially available P(O)Ph(i-Bu)(OH), and its
anion [PO2Ph(i-Bu)]-, were generated for comparison to reac-
tion mixtures (see the Experimental Section), but the fate of
the PPh(i-Bu) group could not be determined. Attempts to
identify the anion (or anions) in cation 8 by elemental analyses
and mass spectroscopy were also unsuccessful.
The crystal structure of 12‚H2O (see Figure 5 and Table 4)
showed distorted-tetrahedral geometry at P and the presence of
a water molecule hydrogen-bonded to the PdO group.24 The
O‚‚‚O distance of 2.667 Å is similar to that found in related
hydrogen-bonded adducts of triphenylphosphine oxide.25
(21) Treatment of PHPh(i-Bu) with s-BuLi in petroleum ether gave a
white precipitate, presumably LiPPh(i-Bu), which was redissolved in THF
for 31P NMR characterization. The observed chemical shift was surprisingly
close to that of the phosphine, but direct reaction of PHPh(i-Bu) and s-BuLi
in THF gave the same results. This material was not soluble in toluene,
preventing direct comparison with the results from decomposition of 6. The
observed chemical shifts are consistent with an earlier report: Grim, S. O.;
Molenda, R. P. Phosphorus Relat. Group V Elem. 1974, 4, 189-193.
(22) For oxidation of terminal phosphido complexes, see: (a) Mastrorilli,
P.; Latronico, M.; Nobile, C. F.; Suranna, G. P.; Fanizzi, F. P.; Englert, U.;
Ciccarella, G. Dalton Trans. 2004, 1117-1119. (b) Giner Planas, J.;
Gladysz, J. A. Inorg. Chem. 2002, 41, 6947-6949. (c) Buhro, W. E.; Zwick,
B. D.; Georgiou, S.; Hutchinson, J. P.; Gladysz, J. A. J. Am. Chem. Soc.
1988, 110, 2427-2439. (d) Buhro, W. E.; Georgiou, S.; Hutchinson, J. P.;
Gladysz, J. A. J. Am. Chem. Soc. 1985, 107, 3346-3348. (e) Ebsworth, E.
A. V.; Gould, R. O.; McManus, N. T.; Rankin, D. W. H.; Walkinshaw, M.
D.; Whitelock, J. D. J. Organomet. Chem. 1983, 249, 227-242.
(23) We have observed the same trans influence ordering in related Pt-
(Me-Duphos) phosphido complexes and their oxidized derivatives: Scriban,
C.; Glueck, D. S.; DiPasquale, A. G.; Dougherty, W.; Rheingold, A. L.
Manuscript in preparation.
Conclusions
The terminal phosphido complexes Pt(diphos)(Me)(PPh(R))
(1, 6, and 10) acted as ligands to the [Pt(diphos)(Me)]+ fragment,
yielding the dinuclear µ-phosphido complexes [(Pt(diphos)-
(Me))2(µ-PPh(R))]+ (7, 8, and 11). Fluxional behavior in the
unsymmetrically bridged cations 8 and 11 was consistent with
restricted rotation about the Pt-PPh(i-Bu) bonds; it resulted in
two diastereomers for 8 and four for 11 at low temperature.
Comparison of the 31P NMR data before and after complexation
and the X-ray crystal structures of 10 and 11 were consistent
with changes in the geometry at phosphorus (from distorted
pyramidal, with a stereochemically active lone pair, to tetrahe-
(25) (a) Chandrasekhar, S.; Kulkarni, G.; Muktha, B.; Row, T. N. G.
Tetrahedron: Asymmetry 2003, 14, 3769-3772. (b) Steiner, T. Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 2000, C56, 1033-1034. (c)
Gramstad, T.; Husebye, S.; Maartmann-Moe, K. Acta Chem. Scand. 1986,
B40, 26-30.
(24) Edmundson, R. S. Chemical Properties and Reactions of Phosphine
Chalcogenides. In The Chemistry of Organophosphorus Compounds;
Hartley, F. R., Ed.; Wiley: Chichester, U.K., 1992; Vol. 2, pp 287-407.

3376 Organometallics, Vol. 25, No. 14, 2006
Scriban et al.
of Pt(dppe)(Me)(PPh(i-Bu)) (6; 154.8 mg, 0.2 mmol) in 5 mL of
THF. The reaction mixture turned off-white. The solvent was
removed under vacuum, and petroleum ether was added to the
viscous residue, yielding a light yellow precipitate, which was dried
under vacuum to yield 200 mg (65%) of light yellow powder. We
were unable to remove trace impurities by recrystallization from
CH2Cl2/ether; thus, analytically pure material was not obtained.
dral) on conversion of the terminal phosphido ligand to a
bridging group.
Experimental Section
Unless otherwise noted, all reactions and manipulations were
performed in dry glassware under a nitrogen atmosphere at 20 °C
in a drybox or using standard Schlenk techniques. Petroleum ether
(bp 38-53 °C), ether, THF, toluene, and CH2Cl2 were dried using
columns of activated alumina.26 Deuterated solvents used for NMR
spectroscopy were dried over molecular sieves and degassed. NMR
spectra were recorded using Varian 300 and 500 MHz spectrom-
eters. 1H and 13C NMR chemical shifts are reported vs Me4Si and
Anal. Calcd for C65H68F3O3P5Pt2S: C, 50.98; H, 4.48. Found:
C, 49.61; H, 4.72. HRMS (m/z): calcd, 1381.3305; found, 1381.3474.
See Table 2 and the accompanying discussion for more information
on the temperature-dependent 31P NMR spectra. 31P{1H} NMR
(CD2Cl2): δ 52.8 (broad d, J ) 329, JPt-P ) 2338), 50.5 (broad d,
J ) 352, JPt-P ) 2408), 48.5 (broad, JPt-P ) 1906), 47.6 (broad,
1
were determined by reference to the residual H and 13C solvent
JPt-P ) 1800), 1.0 (apparent tt, “J” ) 339, 15, apparent JPt-P
)
peaks. 31P NMR chemical shifts are reported vs H3PO4 (85%) used
as an external reference. Coupling constants are reported in Hz, as
absolute values unless noted otherwise. Unless indicated, peaks in
NMR spectra are singlets. IR spectra were obtained on KBr pellets
and are reported in cm-1. Elemental analyses were provided by
Schwarzkopf Microanalytical Laboratory. Mass spectra were
recorded at the University of Illinois Urbana-Champaign. Unless
otherwise noted, reagents were obtained from commercial suppliers.
The following compounds were made by the literature procedures:
Pt(COD)(Me)Cl,7 Pt(dppe)(Me)(Cl).6 The phosphido complexes Pt-
(dppe)(Me)(PPh(R)) (R ) Ph, i-Bu) were prepared as previously
reported3a or by the new method described below.
Pt(dppe)(Me)(PPh(i-Bu)) (6). We previously reported the
synthesis of this complex by treatment of Pt(dppe)(Me)(OMe) with
PHPh(i-Bu).3a Since the Pt-methoxide complex was made from
Pt(dppe)(Me)(Cl), the new procedure is more convenient. PHPh-
(i-Bu) (41.6 mg, 0.25 mmol) was added with a microsyringe to a
stirred slurry of Pt(dppe)(Me)(Cl) (161 mg, 0.25 mmol) in toluene
(20 mL). NaOSiMe3 (28.1 mg, 0.25 mmol) in toluene (10 mL) was
added to the reaction mixture, which turned yellow; a white
precipitate formed. The slurry was filtered through Celite, and the
yellow filtrate was concentrated under vacuum. Petroleum ether
was added to the yellow residue, yielding a yellow precipitate,
which was washed further with petroleum ether. Drying the
precipitate yielded 155 mg (80%) of yellow powder. Pt(dppe)(Me)-
(PPh2) was prepared similarly (82% yield).
[(Pt(dppe)(Me))2(µ-PPh2)][OTf] (7). A solution of AgOTf (51.4
mg, 0.2 mmol) in 2 mL of THF was added to a stirred slurry of
Pt(dppe)(Me)(Cl) (128.8 mg, 0.2 mmol) in 10 mL of THF. A white
precipitate formed immediately. The slurry was filtered through
Celite, and the filtrate was added to a bright yellow solution of
Pt(dppe)(Me)(PPh2) (1; 158.8 mg, 0.2 mmol) in 10 mL of THF.
The white precipitate that formed in about 5 min was washed with
THF (three 5 mL portions) and dried under vacuum, yielding 195
mg (63%) of white powder. The white powder was dissolved in
the minimum amount of CH2Cl2 and cooled to -25 °C overnight,
yielding white crystals.
Anal. Calcd for C67H64F3O3P5Pt2S: C, 51.87; H, 4.16. Found:
C, 52.07; H, 4.32. 31P{1H} NMR (CD2Cl2; see Table 2): δ 52.3
(broad dd, J ) 341, 16, JPt-P ) 2450), 49.2 (broad d, J ) 16, JPt-P
) 1895), 26.8 (apparent tt with fine structure on the central peak,
J ) 341, 16, JPt-P ) 2313). 1H NMR (CD2Cl2): δ 7.67-7.49 (broad
m, 12H, Ar), 7.49-7.42 (broad m, 8H, Ar), 7.35 (td, J ) 7, 2, 4H,
Ar), 7.22-7.19 (m, 8H, Ar), 7.18-7.14 (m, 8H, Ar), 7.00-6.97
(m, 2H, Ar), 6.88-6.84 (m, 4H, Ar), 6.68-6.63 (m, 4H, Ar), 2.12-
1.90 (m, 8H), 0.91-0.86 (m, 6H, JPt-H ) 61, Pt-Me).
2289). 31P{1H} NMR (CD2Cl2, -20 °C): δ 53.2 (dd, J ) 337, 6,
JPt-P ) 2330), 50.4 (dd, J ) 339, 4, JPt-P ) 2405), 48.6 (d, J )
15, JPt-P ) 1886), 47.2 (d, J ) 15, JPt-P ) 1863), 0.8 (overlapping
ddt, J ) 339, 337, 15, JPt-P ) 2243, 2319). 31P{1H} NMR (CD2-
Cl2, -40 °C): δ 53.9 (broad d, J ) 334, JPt-P ) 2331, b), 53.5 (d,
J ) 334, JPt-P ) 2331, a), 50.7 (broad d, J ) 340, JPt-P ) 2405,
b), 50.4 (d, J ) 340, JPt-P ) 2405, a), 49.1 (broad, JPt-P ) 1903,
b), 48.7 (d, J ) 15, JPt-P ) 1889, a), 47.4 (broad, JPt-P ) 1883,
b), 47.0 (d, J ) 15, JPt-P ) 1864, a), 1.2 (broad t, “J” ) 338, b),
0.9 (tt, J ) 340, 334, 15, JPt-P ) 2319, 2231, a). 31P{1H} NMR
(DMSO-d6, 100 °C): δ 51.7 (d, J ) 338, JPt-P ) 2382), 48.3
(apparent d, J ) 15, JPt-P ) 1871), 2.3 (apparent t, J ) 338,
1
apparent JPt-P ) 2280). H NMR (DMSO-d6, 21 °C; the signals
were broad, so it was not possible to integrate them all reliably;
peaks are assigned where possible): δ 7.80-7.62 (m, 4H, Ar),
7.62-7.50 (m, 14H, Ar), 7.50-7.40 (broad m, 10H, Ar), 7.40-
7.12 (m, 7H, Ar), 7.12-7.06 (m, 2H, Ar), 7.06-6.90 (broad, 2H,
Ar), 6.76-6.70 (m, 2H, Ar), 6.70-6.63 (m, 2H, Ar), 6.56-6.36
(broad, 2H, Ar), 2.50 (m, 1H, CH), 2.45-2.30 (m, 2H, CH2), 2.30-
1.60 (broad m, CH2), 1.30-1.00 (broad m, 3H, Pt-CH3), 0.90-
0.55 (broad m, 3H, Pt-CH3), 0.55-0.35 (broad m, CH3), 0.35-
0.10 (broad m, CH3). 1H NMR (DMSO-d6, 100 °C): δ 7.67-7.50
(m, 16H, Ar), 7.49-7.43 (m, 6H, Ar), 7.43-7.38 (m, 2H, Ar),
7.38-7.32 (m, 4H, Ar), 7.32-7.25 (m, 8H, Ar), 7.25-7.10 (broad
m, 4H, Ar), 7.09-7.03 (m, 1H, Ar), 6.88-6.81 (m, 2H, Ar), 6.76-
6.71 (m, 2H, Ar), 2.51-2.50 (m, 1H, CH), 2.45-2.25 (m, 4H, CH2),
2.20-2.00 (m, 4H, CH2), 1.70-1.60 (broad, 2H, CH2), 1.02 (d, J
) 7, JPt-H ) 63, 6H, Pt-Me), 0.50 (d, J ) 6, 6H, Me).
Pt((R,R)-Me-Duphos)(Me)(Cl) (9). A solution of (R,R)-Me-
Duphos (173 mg, 0.565 mmol) in CH2Cl2 (2 mL) was added
dropwise to a solution of Pt(COD)(Me)(Cl) (200 mg, 0.565 mmol)
in CH2Cl2 (3 mL) to give a pale yellow solution. In the air, the
solvent was removed under reduced pressure and the remaining
crystals were washed with Et2O (3 × 2 mL) and recrystallized from
CH2Cl2/Et2O at -25 °C to yield 247 mg (79%) of white crystals,
suitable for single-crystal X-ray diffraction.
Anal. Calcd for C19H31ClP2Pt: C, 41.35; H, 5.66. Found: C,
41.31; H, 5.74. 31P{1H} NMR (CDCl3): δ 72.3 (d, J ) 4, JPt-P
)
1722), 61.4 (d, J ) 4, JPt-P ) 4065). 1H NMR (CDCl3): δ 7.69-
7.63 (m, 2H, Ar), 7.57-7.55 (m, 2H, Ar), 3.24-3.18 (m, 1H),
3.06-2.96 (m, 1H), 2.82-2.69 (m, 2H), 2.40-2.25 (m, 4H), 2.02-
1.94 (m, 1H), 1.89-1.63 (m, 3H), 1.45-1.40 (dd, J ) 18, 7, 3H,
Me), 1.29-1.24 (dd, J ) 18, 7, 3H, Me), 0.90-0.86 (dd, J ) 15,
7, 3H, Me), 0.86-0.82 (dd, J ) 15, 7, 3H, Me), 0.71-0.60 (dd, J
) 7, 2, JPt-H ) 53, 3H, Me). 13C{1H} NMR (CDCl3): δ 144.2
(dd, J ) 38, 49, quat), 142.6 (dd, J ) 25, 36, quat), 133.1 (d, J )
13, Ar), 132.1 (dd, J ) 4, 15, Ar), 131.3-131.1 (m, Ar), 40.8 (d,
J ) 26), 40.1 (d, J ) 39), 37.3-36.7 (m), 35.6 (d, J ) 26), 17.2
(3-line pattern, Me), 14.4 (d, J ) 2, Me), 14.1 (Me), 6.5 (dd, J )
6, 97, Pt-Me).
[(Pt(dppe)(Me))2(µ-PPh(i-Bu))][OTf] (8). A solution of AgOTf
(51.4 mg, 0.2 mmol) in 2 mL of THF was added to a stirred slurry
of Pt(dppe)(Me)(Cl) (128.8 mg, 0.2 mmol) in 5 mL of THF. A
white precipitate formed immediately. The slurry was filtered
through Celite, and the filtrate was added to a bright yellow solution
Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10). PHPh(i-Bu) (33.2
mg, 0.2 mmol) was added with a microsyringe to a stirred slurry
of Pt((R,R)-Me-Duphos)(Me)(Cl) (110.4 mg, 0.2 mmol) in toluene
(26) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518-1520.

Pt(II) Phosphido Complexes as Metalloligands
Organometallics, Vol. 25, No. 14, 2006 3377
(20 mL). NaOSiMe3 (22.4 mg, 0.2 mmol) in toluene (10 mL) was
added to the reaction mixture, which turned yellow. After it was
stirred for 12 h, the slurry was filtered through Celite, and the yellow
filtrate was concentrated under vacuum. Petroleum ether was added
to the yellow residue, yielding a yellow precipitate, which was
washed further with petroleum ether. Drying the precipitate yielded
122 mg (90%) of yellow powder. The following NMR spectra are
reported for the mixture of two diastereomers a and b (ratio 1.2:
1), unless otherwise indicated. Recrystallization from petroleum
ether at -25 °C gave X-ray-quality crystals.
all the Me-Duphos peaks could be resolved/assigned)): δ 68.7 (JPt-P
) 1797), 68.4 (JPt-P ) 1803), 67.2 (d, J ) 339), 66.9 (d, J )
339), 66.6 (d, J ) 328), 66.0 (d, J ) 331), 65.2 (JPt-P ) 1849),
64.9 (JPt-P ) 1860), 64.2 (JPt-P ) 1864), 63.9 (JPt-P ) 1858), 2.9
(broad t, J ) 334, JPt-P ) 2300, a1), 2.6 (tt-like pattern, J ) 331,
14, JPt-P ) 2300, a2), -10.1 (broad t, J ) 335, JPt-P ) 2240, b1),
-10.3 (tm, J ) 335, JPt-P ) 2240, b2). 31P{1H} NMR (CD2Cl4,
100 °C): δ 66.6 (broad, JPt-P ) 1834), 65.9 (broad d, J ) 340,
JPt-P ) 2325), 65.8 (broad d, J ) 335, JPt-P ) 2330), 65.6 (broad,
JPt-P ) 1801), -2.1 (very broad).
Decomposition of Pt(dppe)(Me)(PPh(i-Bu)) (6). A bright
yellow solution of Pt(dppe)(Me)(PPh(i-Bu)) (6; 143 mg, 0.185
mmol) in toluene (15 mL) was heated in a sealed ampule at 50 °C
for 3 days, during which time a white precipitate formed and the
solution became pale yellow. The first crop was collected on a fine
frit, washed with petroleum ether, and dried to give 21 mg of an
off-white solid. The yellow mother liquor was heated for an
additional week to give a second crop (81 mg). The combined crops
were recrystallized from CH2Cl2/ether at -25 °C to give 70 mg of
white solid (54%; calculated for [(Pt(dppe)(Me))2(µ-PPh(i-Bu))]-
[OH], since the nature of the anion is not known).
Anal. Calcd for C29H45P3Pt: C, 51.10; H, 6.65. Found: C, 50.70;
H, 7.07. 31P{1H} NMR (21 °C, C6D6): δ 67.6 (broad d, J ) 116,
JPt-P ) 1779, a), 62.7 (broad, JPt-P ) 1776, a), -61.3 (broad d, J
) 120, JPt-P ) 1026, a), 66.3 (d, broad, J ) 116, Pt satellites not
resolved, b), 62.6 (broad, JPt-P ) 1743, b), -56.7 (broad d, J )
108, JPt-P ) 970, b). 31P{1H} NMR (-40 °C, toluene-d8; diaste-
reomer a): δ 69.6 (dd, J ) 131, 8, JPt-P ) 1816), 64.2 (dd, J )
21, 9, JPt-P ) 1768), -63.9 (dd, J ) 130, 18, JPt-P ) 1011). 31P-
{1H} NMR (-40 °C, toluene-d8; diastereomer b): δ 67.8 (dd, J )
128, 8, JPt-P ) 1808), 64.2 (dd, J ) 21, 9, JPt-P ) 1768), -57.3
(dd, J ) 129, 23, JPt-P ) 999). The chemical shift for the cis
phosphorus, as well as JPt-P, was the same for both diastereomers.
1H NMR (C6D6): δ 7.93 (broad, 2H, Ar), 7.33-7.30 (m, 1H, Ar),
7.28-7.25 (m, 2H, Ar), 7.21-7.18 (m, 1H, Ar), 7.06-6.99 (m,
3H, Ar), 3.65-3.62 (m, 1H, CH), 2.80-2.66 (broad, 1H), 2.58-
2.47 (m, 2H), 2.40-2.31 (m, 2H), 2.23-2.16 (m, 1H), 2.08-2.00
(m, 2H), 1.90-1.70 (m, 2H), 1.56-1.46 (m, 1H), 1.51 (dd, J )
18, 7, 3H, Me), 1.45-1.35 (m, 1H), 1.33 (d, J ) 7, 6H, Me), 1.31-
1.24 (m, 2H), 1.21 (td, J ) 7, 3, 3H, Pt-Me), 1.15 (dd, J ) 18, 7,
3H, Me), 0.76 (dd, J ) 14, 7, 3H, Me), 0.64 (dd, J ) 14, 7, 3H,
Me). 13C{1H} NMR (C6D6): δ 147.4 (m, quat), 145.8-145.5 (m,
quat), 133.2 (dd, J ) 50, 14, Ar), 130.2 (dm, J ) 42, Ar), 128.3
(Ar), 127.0 (d, J ) 3, Ar), 123.9 (m, Ar), 41.5 (d, J ) 27), 40.8 (d,
J ) 26), 37.7-37.4 (m), 36.9 (m), 35.5-34.9 (m), 34.4-33.5 (m),
29.5 (broad), 25.5 (d, J ) 7), 25.2 (broad), 22.7, 17.5-17.0 (m),
14.2 (d, J ) 8), 13.9.
Anal. Calcd for C64H68P5Pt2OH (8-OH): C, 54.94; H, 4.97. Anal.
Calcd for C64H68P5Pt2Cl (8-Cl): C, 54.22; H, 4.83. Found: C,
53.61; H, 5.36. 31P{1H} NMR: see Table 2 and data for the triflate
1
salt above. H{31P} NMR (CD2Cl2, -60 °C; relative integrals are
not reported, signals are assigned where possible): δ 7.87-7.84
(m, Ar), 7.81-7.78 (m, Ar), 7.65-7.32 (m, Ar), 7.18-7.11 (m,
Ar), 7.04-7.00 (m, Ar), 6.93-6.86 (broad m, Ar), 6.67-6.62 (m,
Ar), 6.51-6.48 (broad, Ar), 6.23-6.21 (m, Ar), 2.68-2.63 (m),
2.27-2.04 (m), 1.84-1.58 (m), 1.22 (JPt-H ) 63, Pt-Me), 0.81
(JPt-H ) 60, Pt-Me), 0.76 (broad), 0.15 (broad). Low-resolution
FAB MS (Magic Bullet; m/z): 1535.5, 1415.3, 1381.3 (M+), 1365.2,
1289.2, 1109.2, 791.1, 773.1, 758.1, 717.1, 702.1, 678.9, 634.9,
592.0, 558.9, 527.8, 484.9, 408.9, 301.9, 183.0. IR: 3044, 2922,
1622, 1483, 1433, 1411, 1311, 1183, 1100, 1000, 878, 822, 744,
700, 533, 489.
[Pt((R,R)-Me-Duphos)(Me))2(µ-PPh(i-Bu))][OTf] (11). A solu-
tion of AgOTf (19.8 mg, 0.08 mmol) in 2 mL of THF was added
to a solution of Pt((R,R)-Me-Duphos)(Me)(Cl) (42.5 mg, 0.08
mmol) in 5 mL of THF. A white precipitate formed immediately.
The slurry was filtered through Celite, and the filtrate was added
to a yellow solution of Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (52.5
mg, 0.08 mmol) in 5 mL of THF, yielding a colorless solution.
The solution was concentrated under vacuum, and petroleum ether
was added to the white residue, yielding a white precipitate. The
precipitate was washed with petroleum ether (three 3 mL portions)
and dried under vacuum, yielding 90 mg (87%) of a white powder,
which was recrystallized from THF and petroleum ether to give
crystals of a THF solvate suitable for X-ray crystallography. A
sample for elemental analysis, recrystallized from THF/petroleum
The decomposition of 6 was repeated several times in analogous
experiments, with monitoring by 31P NMR spectroscopy, in attempts
to identify the anion of 8 and the fate of the PPh(i-Bu) group (see
Scheme 5 and related discussion above). For details of these
experiments, see the Supporting Information.
Pt(dppe)(Me)(P(O)Ph(i-Bu)) (12). Pt(dppe)(Me)(PPh(i-Bu))
(101 mg, 0.13 mmol) was dissolved in 5 mL of toluene to yield a
yellow solution, which was transferred to an NMR tube fitted with
a rubber septum. H2O2 (30% in H2O, 30 µL, 0.26 mmol) was added
with a microliter syringe. The reaction mixture turned into a white
suspension, and gas evolved. 31P NMR spectroscopy indicated the
formation of Pt(dppe)(Me)(P(O)Ph(i-Bu)) (12). The solvent was
removed under vacuum, and the white residue was washed with
petroleum ether (three 3 mL portions). Drying the precipitate yielded
95 mg (93%) of white powder. Recrystallization from CD2Cl2 and
petroleum ether at 5 °C gave crystals of a monohydrate, as observed
by X-ray crystallography and elemental analysis.
1
ether, also contained THF, as quantified by integration of the H
NMR spectrum in CD2Cl2.
At room temperature in CD2Cl2, the two diastereomers a and b
were observed in a 2.5:1 ratio. At low temperature, the four
diastereomers a1, a2, b1, and b2 (1.7:2.3:1:1.4 ratio) were observed.
The following NMR spectra are reported for the mixture, with
assignments given where possible.
Anal. Calcd for C37H41OP3Pt‚H2O: C, 55.02; H, 5.37. Found:
C, 54.72; H, 5.48. 31P{1H} NMR (C6D6): δ 58.7 (dd, J ) 411, 23,
JPt-P ) 3006), 48.6 (d, J ) 23, JPt-P ) 1897), 46.4 (d, J ) 411,
JPt-P ) 1714). 1H NMR (CD2Cl2): δ 7.90-7.86 (m, 2H, Ar), 7.65-
7.58 (m, 6H, Ar), 7.53-7.39 (m, 12H, Ar), 7.32 (td, J ) 8, 2, 2H,
Ar), 7.20-7.19 (m, 3H, Ar), 2.36-1.96 (m, 6H), 1.58-1.54 (m,
1H), 0.98 (d, J ) 7, 3H, CH3, i-Bu), 0.75 (d, J ) 7, 3H, CH3,
i-Bu), 0.57 (m, JPt-H ) 66, 3H, Pt-CH3). 13C{1H} NMR (CD2-
Cl2): δ 134.3 (d, J ) 11, Ar), 134.0 (d, J ) 12, Ar), 133.8 (d, J
) 2, Ar), 133.7 (d, J ) 1, Ar), 133.6 (d, J ) 2, Ar), 133.5 (d, J )
1, Ar), 131.9 (d, J ) 30, Ar), 131.5 (d, J ) 30, Ar), 131.4 (d, J )
2, Ar), 131.3 (d, J ) 2, Ar), 130.8 (d, J ) 2, Ar), 130.6 (d, J ) 2,
Ar), 130.3 (Ar), 130.2 (Ar), 129.2 (d, J ) 4), 129.1 (d, J ) 4),
128.6 (d, J ) 7), 128.5 (d, J ) 7), 128.0 (d, J ) 2), 127.4 (d, J )
Anal. Calcd for C49H76F3O3P5Pt2S‚0.2C4H8O: C, 43.93; H, 5.74.
Found: C, 44.25; H, 5.69. 31P{1H} NMR (CD2Cl2): δ 69.3 (broad,
JPt-P ) 1840), 67.5 (broad d, J ) 334, JPt-P ) 2292), 65.2 (broad,
JPt-P ) 1750), 5.5 (broad t-like pattern, J ) 336, JPt-P ) 2246, a),
1
-7.1 (broad t-like pattern, J ) 304, JPt-P ) 2307, b). H NMR
(CD2Cl2): δ 7.94 (broad, 2H, Ar), 7.76-7.71 (m, 2H, Ar), 7.67-
7.62 (m, 2H, Ar), 7.60-7.54 (m, 4H, Ar), 7.30-7.26 (m, 2H, Ar),
7.18-7.14 (m, 1H, Ar), 3.20-1.50 (m, 27H, CH + CH2), 1.44-
0.98 (m, 21H, Me), 0.92-0.81 (m, 12H, Me), 0.50-0.18 (broad,
3H, Me). 31P{1H} NMR (CD2Cl2, -60 °C, selected signals (not

3378 Organometallics, Vol. 25, No. 14, 2006
Scriban et al.
9, Ar), 45.1 (dd, J ) 36, 10, CH2, i-Bu), 31.3-30.9 (m, CH2),
29.6-29.3 (m, CH2), 25.4 (d, J ) 8, CH3, i-Bu), 25.0 (CH, i-Bu),
27.9 (d, J ) 7, CH3, i-Bu), -1.7 (dd, J ) 80, 6, Pt-Me).
Decomposition of 6 in the Presence of H2O. A bright yellow
solution of 6 (15 mg, 0.019 mmol) in toluene (0.5 mL) was
transferred into an NMR tube, which was fitted with a septum,
under N2. H2O (1 µL, 0.02 mol) was added via a microliter syringe,
and the mixture was monitored by 31P NMR spectroscopy. After 2
weeks, the solution turned colorless, colorless crystals (presumably
8) formed on the walls of the NMR tube, and 12 was observed by
31P NMR spectroscopy.
Decomposition of 6 in the Presence of H2O and Air. A bright
yellow solution of 6 (15 mg, 0.019 mmol) in toluene (0.5 mL) was
transferred into an NMR tube. H2O (1 µL, 0.02 mol) was added
via a microliter syringe. The tube was left uncapped in the air, and
the mixture was monitored by 31P NMR spectroscopy. After 1 day,
the solution became pale yellow and complexes 12 and 6 were
observed. After 3 days, the solution turned colorless, and 12 was
the only species observed by 31P NMR. White flakes formed on
the walls of the NMR tube; they turned into white crystals after 2
weeks. The solution was removed from the NMR tube; the crystals
on the walls were washed with toluene, dissolved in CDCl3, and
shown, by 31P NMR spectroscopy, to contain cation 8. Two other
peaks were also observed at 26.9 and 26.7 ppm. The toluene
solution was mixed with the toluene washings, and the solvent was
removed under vacuum. The white residue was redissolved in
CDCl3, and 31P NMR spectroscopy showed that it was 12. An
additional peak at 33.8 ppm was also observed.
Decomposition of a Mixture of Pt(dppe)(Me)(PPh(i-Bu)) (6)
and Pt(dppe)(Me)(P(O)Ph(i-Bu)) (12). A solution of 6 (39 mg,
0.05 mmol) in toluene (0.2 mL) was mixed with a solution of 12
(40 mg, 0.05 mmol) in toluene (0.3 mL). The mixture was
transferred to an NMR tube, which was stored in a glovebox and
monitored by 31P NMR spectroscopy. After 10 days, the main
components of the solution were 6 and 12, but a small amount of
cation 8, along with several new peaks (δ 31.7, 29.6, 19.7, -11.6),
was observed. After 2 months, a considerable amount of white
precipitate had formed, and white crystals grew on the walls of the
NMR tube. The intensity of the new peaks increased, and other
new peaks were observed (δ -34.1, -34.5, -39.7 broad). The
solution was decanted. The crystals on the walls of the NMR tube
were dissolved in CH2Cl2; 31P NMR spectroscopy showed that they
were a mixture of cation 8 and 12.
Acknowledgment. We thank the National Science Founda-
tion for support and Cytec Canada for gifts of phosphines.
Supporting Information Available: Text and tables giving
details of additional experiments on the formation of 8 from 6 and
details of the crystallographic studies; crystallographic data are also
given as CIF files. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM050149P