Reactivity of a secondary phosphine platinum(II) complex with [Pt(norbornene)3] and PPh3. Synthesis of new single phosphido-bridged derivatives of platinum(I) and phosphido-bridged platinum(II) hydrides

Article abstract of DOI:10.1021/om0007973

The reaction between cis-[Pt(C₆F₅)₂ (PPh₂H)₂], [Pt(norbornene)₃], and PPh₃ (1:1:1) results in the formation of the Pt(II) derivatives [(C₆F₅)₂Pt(μ-PPh₂) (μ-H)Pt(PPh₂H)(PPh₃)] (1) and [{(C₆F₅)(PPh₃)Pt(μ-PPh₂) (μ-H)}₂Pt] (2). For the molar ratio 1:1:2 the reaction proceeds with with formation of the Pt(I) derivative [(C₆F₅) (PPh₃)Pt(μ-PPh₂)Pt(PPh₃)₂] (3) and the Pt(II) derivatives [(C₆F₅)₂Pt(μ- PPh₂)(μ-H)Pt(PPh₃)₂] (4) and [(C₆F₅)(PPh₃)Pt(μ- PPh₂)₂Pt(H)(PPh₃)] (5). The structures of complexes 2, 3, and 5 have been established by X-ray diffraction. Spectroscopic (IR and NMR) data are also given.

Full text of DOI:10.1021/om0007973

850
Organometallics 2001, 20, 850-859
Rea ctivity of a Secon d a r y P h osp h in e P la tin u m (II)
Com p lex w ith [P t(n or bor n en e)3] a n d P P h 3. Syn th esis of
New Sin gle P h osp h id o-Br id ged Der iva tives of
P la tin u m (I) a n d P h osp h id o-Br id ged P la tin u m (II)
Hyd r id es†,‡
Ester Alonso,§ J uan Fornie´s,*,§ Consuelo Fortun˜o,§ Antonio Mart´ın,§,| and
A. Guy Orpen|
Departamento de Quı´mica Inorga´nica and Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and School of Chemistry,
University of Bristol, Cantocks Close, Bristol, U.K. BS8 ITS
Received September 18, 2000
The reaction between cis-[Pt(C6F5)2(PPh2H)2], [Pt(norbornene)3], and PPh3 (1:1:1) results
in the formation of the Pt(II) derivatives [(C6F5)2Pt(µ-PPh2)(µ-H)Pt(PPh2H)(PPh3)] (1) and
[{(C6F5)(PPh3)Pt(µ-PPh2)(µ-H)}2Pt] (2). For the molar ratio 1:1:2 the reaction proceeds with
formation of the Pt(I) derivative [(C6F5)(PPh3)Pt(µ-PPh2)Pt(PPh3)2] (3) and the Pt(II)
derivatives [(C6F5)2Pt(µ-PPh2)(µ-H)Pt(PPh3)2] (4) and [(C6F5)(PPh3)Pt(µ-PPh2)2Pt(H)(PPh3)]
(5). The structures of complexes 2, 3, and 5 have been established by X-ray diffraction.
Spectroscopic (IR and NMR) data are also given.
In tr od u ction
tives of the type [M2(µ-PR2)2L2(PR2H)2] with palladium-
(0) or platinum(0) complexes. Thus, the oxidative addi-
tion of the P-H bond of a secondary phosphine to
zerovalent complexes of platinum or palladium provides
easy access to polynuclear phosphido-bridged complexes.
The dinuclear Pd(I) complexes [Pd2(µ-PR2)2(PR2H)2]
(R ) But, Cy) have been synthesized1 by reacting PdCp-
(η3-C3H5) with PR2H. For R ) But the reaction is carried
out through the intermediate formation of the Pd(0)
In the past few years we have been involved in the
synthesis of palladium and/or platinum polynuclear
derivatives with bridging diphenylphosphido ligands.
The precursors of this type of phosphido complexes were
often Li2[cis-Pt(C6F5)2(PPh2)2] (M ) Pd, Pt), prepared
in situ by deprotonation of metal-coordinated secondary
phosphines in cis-[Pt(C6F5)2(PPh2H)2],5 which by react-
ing with several Pt(II) derivatives are able to produce
an interesting family of polynuclear phosphido palla-
dium(II) or platinum(II) derivatives. In this paper we
describe the reactions between cis-[Pt(C6F5)2(PPh2H)2]
and the platinum(0) complex [Pt(norbornene)3] in the
presence of different molar ratios of PPh3, which give
different types of phosphido- or phosphido/hydrido-
bridged platinum(I) or -(II) complexes.
complex Pd(PBut H)2 and oxidative addition of a P-H
2
bond. When the secondary phosphine is PPh2H, the
complex [Pd2(µ-PPh2)2(PPh2H)3] is obtained, and this
dinuclear complex cannot be obtained from [Pd-
(PPh2H)4].2 Some heterometallic platinum µ-phosphido
complexes in which the bridging phosphido moiety M(µ-
PR2)Pt is formed by reacting a transition-metal complex
containing PR2H with zerovalent complexes of platinum
have been reported.3 The synthesis of palladium or
platinum trinuclear clusters in mixed formal oxidation
state and displaying the M3(µ-PR2)3 core has been
carried out in some cases4 by reacting dinuclear deriva-
† Polynuclear Homo- or Heterometallic Palladium(II)-Platinum(II)
Pentafluorophenyl Complexes Containing Bridging Diphenylphosphido
Ligands. 9. Part 8: ref 13b.
‡ Dedicated to Prof. Rafael Uso´n on the occasion of his 75th birthday.
§ Universidad de Zaragoza-CSIC.
Resu lts a n d Discu ssion
| University of Bristol.
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Rea ction of cis-[P t(C6F 5)2(P P h 2H)2] w ith [P t-
(C7H10)3] (C7H10 ) η2-n or bor n en e) a n d P P h 3 in a
1:1:1 Mola r Ra tio. The results of the reaction between
cis-[Pt(C6F5)2(PPh2H)2] and [Pt(C7H10)3] (1:1 molar ratio)
in the presence of PPh3 depend on the amount of PPh3
used. When cis-[Pt(C6F5)2(PPh2H)2] is added at room
temperature to a toluene solution of [Pt(C7H10)3] and
PPh3 in a 1:1:1 molar ratio, the dinuclear hydride-
bridged Pt(II) complex [(C6F5)2Pt(µ-PPh2)(µ-H)Pt(PPh2H)-
(PPh3)] (1; 36% yield) is obtained (Scheme 1). In
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10.1021/om0007973 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 02/01/2001

Phosphido-Bridged Derivatives of Pt(I) and Pt(II)
Organometallics, Vol. 20, No. 5, 2001 851
Sch em e 1
addition, as we will see later, by workup of the mother
liquors a trinuclear platinum(II) derivative, [{(C6F5)-
(PPh3)Pt(µ-PPh2)(µ-H)}2Pt] (2; 21% yield), is obtained.
The structure of 1 (Scheme 1) has been established
on the basis of NMR and IR data and results from the
oxidative addition of one P-H bond to the Pt(0) center
and migration of the PPh2H ligand. Since complex 1 has
a valence electron count of 30, a metal-metal bond
between the two Pt(II) centers should be present.
Hydride-bridged complexes containing other bridging
ligands which contribute to the stability of the dinuclear
unit are known.6-8 The most representative are the
cationic bis(diphenylphosphino)methane-bridged A-
frame species of the type [Pt2X2(µ-H)(µ-dppm)2]+.6 Mixed-
bridge systems of the type Pt(µ-H)(µ-X)Pt (X being a
monodentate ligand) are relatively scarce,7 and only a
few derivatives of Pt(II) with a mixed hydride/phosphide
bridging system have been reported.8
The IR spectrum of 1 shows two absorptions of similar
intensity in the 800 cm-1 region. This is in accord with
the presence of two C6F5 groups bonded to the platinum
center in a cis fashion.9 The absorption due to the
stretching mode of the P-H bond of the secondary
phosphine is observed at 2320 cm-1 10
We have not
.
located the IR absorption of the bridging hydride,
although, as is well-known, such absorptions (ca. 1600
cm-1) are usually weak and often difficult to assign.11
1
The H NMR spectrum unequivocally shows the pres-
ence of a bridging hydrido ligand. The hydrido resonance
is a broad doublet (2J P(3),H ) 81 Hz) centered at -6.0
ppm, the splitting being due to the phosphorus atom of
the trans PPh2H ligand (see Scheme 1 for nuclei
labeling). The 2J P(trans to H),H values for the hydride ligand
2
are diagnostic of the bonding mode. Usually the J P(trans
to H),H values for the hydride ligand are ca. 55-80 Hz
for bridged hydrides, while this coupling is much larger
for terminal hydrides.3c,8d,12 The signal is flanked by
platinum satellites due to the coupling with the two
(6) (a) Brown, M. P.; Puddephatt, R. J .; Rashidi, M.; Seddon, K. R.
J . Chem. Soc., Dalton Trans. 1978, 516. (b) Brown, M. P.; Cooper, S.
J .; Frew, A. A.; Manojlovic-Muir, L.; Muir, K. V.; Puddephatt, R. J .;
Thomson, M. A. J . Chem. Soc., Dalton Trans. 1982, 299. (c) Azam, K.
A.; Puddephatt, R. J . Organometallics 1983, 2, 1396. (d) Azam, K. A.;
Brown, M. P.; Cooper, S. J .; Puddephatt, R. J . Organometallics 1982,
1, 1183. (e) Grossel, M. C.; Batson, R. J .; Moulding, R. P.; Seddon, K.
K. J . Organomet. Chem. 1986, 304, 391. (f) Langrick, C. R.; Pringle,
P. J .; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1985, 1015. (g)
Anderson, G. K. Adv. Organomet. Chem. 1993, 35, 1. (h) Xu, C.;
Anderson, G. K. Organometallics 1994, 13, 3981. (i) Xu, C.; Anderson,
G. K. Organometallics 1996, 15, 1760. (j) Uso´n, R.; Fornie´s, J .; Espinet,
P.; Fortun˜o, C. J . Chem. Soc., Dalton Trans. 1986, 1849.
1
inequivalent platinum atoms, J Pt(1,2),H ) 430 and 537
(8) (a) J ans, J .; Naegeli, R.; Venanzi, L. M.; Albinati, A. J . Orga-
nomet. Chem. 1983, 247, C37. (b) Siedle, A. R.; Newmark, R. A.;
Gleason, W. B. J . Am. Chem. Soc. 1986, 108, 767. (c) Van Leeuwen, P.
W. N. M.; Roobeek, C. F.; Frijns, J . H. G.; Orpen, A. G. Organometallics
1990, 9, 1211. (d) Leoni, P.; Manetti, S.; Pasquali, M. Inorg. Chem.
1995, 34, 749. (e) Bandini, A. L.; Banditelli, G.; Minghetti, G. J .
Organomet. Chem. 2000, 595, 224. (f) Goel, A. B.; Goel, S. Inorg. Chim.
Acta 1984, 90, L33. (g) Leoni, P.; Pasquali, M.; Cittadini, V.; Fortunelli,
A.; Selmi, M. Inorg. Chem. 1999, 38, 5257.
(7) (a) Ara, I.; Falvello, L. R.; Fornie´s, J .; Lalinde, E.; Mart´ın, A.;
Mart´ınez, F.; Moreno, M. T. Organometallics 1997, 16, 5392. (b)
Minghetti, G.; Bandini, A. L.; Banditelli, G.; Bonati, F.; Szostak, R.;
Strouse, C. E.; Knobler, C. B.; Kaesz, H. D. Inorg. Chem. 1983, 22,
2332. (c) Minghetti, G.; Albinati, A.; Banditelli, G. Angew. Chem., Int.
Ed. Engl. 1985, 24, 120. (d) Capdevila, M.; Gonza´lez-Duarte, P.; Mira,
I.; Sola, J .; Glegg, W. Polyhedron 1992, 12, 3091. (e) Carr, N.; Dunne,
B. J .; Mole, L.; Orpen, A. G.; Spencer, J . L. J . Chem. Soc., Dalton Trans.
1991, 863.
(9) Uso´n, R.; Fornie´s, J . Adv. Organomet. Chem. 1988, 288, 219 and
references given therein.
(10) (a) Leoni, P.; Pasquali, M.; Fortunelli, A.; Germano, G.; Albinati,
A. J . Am. Chem. Soc. 1998, 120, 9564. (b) Leoni, P.; Chiaradonna, G.;
Pasquali, M.; Marchetti, F. Inorg. Chem. 1999, 38, 253.
(11) Kaesz, H. D.; Saillant, R. B. Chem. Rev. 1972, 72, 231. See also
refs 7a and 8d.
(12) (a) Moore, D. S.; Robinson, S. D. Chem. Soc. Rev. 1983, 12, 415.
(b) Venanzi, L. M. Coord. Chem. Rev. 1982, 43, 251.

852 Organometallics, Vol. 20, No. 5, 2001
Alonso et al.
Hz. In known diplatinum hydrido complexes, bridging
hydrides display 1J Pt,H values in the range 300-600 Hz,
1
while terminal hydrides give signals with J Pt,H values
in the range 800-1400 Hz.3c,8d,12 Since the C6F5 group
has a high trans influence,9 the value of 430 Hz can be
assigned to the coupling with the platinum center
bonded to the two C6F5 groups. The signal due to the
P-H proton of the secondary phosphine must appear
as a doublet by coupling with P(3). Nevertheless, the
low-field part of this doublet is hidden by signals due
to hydrogen atoms of phenyl groups in this part of the
spectrum. The higher field part of the doublet is
observed as a doublet centered at 6.2 ppm (3J P(1),H ) 9
Hz) with platinum satellites (2J Pt(2),H ) 41 Hz) that
barely emerge from the baseline. Phosphorus-decoupled
1
1H NMR experiments have been carried out. In the H-
{31P} NMR experiment with irradiation in the P(2)
resonance region (18 ppm, PPh3 region, see below), the
observed spectrum is unchanged. Thus, the observed
splittings in the hydride and P-H signals cannot be due
to coupling with P(2) (PPh3 group). When the irradiation
is carried out in the P(3) resonance region (-8 ppm,
PPh2H region, see below), both the signal due to the
bridging hydride and that due to the P-H proton of the
PPh2H ligand change dramatically. This spectrum
shows the signal for the hydride ligand (-6.0 ppm) as
a broad singlet, thus confirming that the coupling of 81
Hz is due to P(3) of the PPh2H ligand. The signal due
to the hydrogen atom of the PPh2H ligand appears as a
doublet (9 Hz) at 6.8 ppm, whereas the high-field signal
F igu r e 1. Structure of the complex [{(C6F5)(PPh3)Pt(µ-
PPh2)(µ-H)}2Pt] (2). Thermal ellipsoids are drawn at the
50% probability level.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [{(C6F 5)(P P h 3)P t(µ-P P h 2)(µ-H)}2P t]‚
C6H12‚3/8C6H14 (2‚C6H12‚3/8C6H14
)
Pt(1)-C(1)
Pt(1)-Pt(2)
Pt(2)-Pt(3)
Pt(3)-P(4)
Pt(1)-P(1)
2.051(6)
Pt(2)-P(1)
Pt(3)-C(7)
Pt(1)-P(3)
Pt(2)-P(2)
Pt(3)-P(2)
2.2249(14)
2.058(5)
2.3137(14)
2.2279(14)
2.2667(14)
2.8474(3)
2.8523(3)
2.3074(15)
2.2638(14)
C(1)-Pt(1)-P(1)
94.96(15) C(1)-Pt(1)-P(3)
94.22(16)
C(1)-Pt(1)-Pt(2) 144.64(15)
P(1)-Pt(1)-P(3) 170.81(5)
P(1)-Pt(1)-Pt(2)
50.03(3)
P(3)-Pt(1)-Pt(2) 120.79(4)
P(1)-Pt(2)-Pt(1)
1
observed in the H NMR spectrum was a doublet (9 Hz)
P(1)-Pt(2)-P(2) 111.01(5)
P(2)-Pt(2)-Pt(1) 161.93(4)
51.23(4)
at 6.2 ppm. Moreover, the spectrum with irradiation in
the P(1) resonance region (111.5 ppm, see below) shows
a singlet at 6.2 ppm due to the P-H proton. Therefore,
P(1)-Pt(2)-Pt(3) 161.08(4)
Pt(1)-Pt(2)-Pt(3) 146.837(10)
P(2)-Pt(2)-Pt(3)
C(7)-Pt(3)-P(2)
51.21(4)
93.48(16) C(7)-Pt(3)-P(4)
93.84(16)
C(7)-Pt(3)-Pt(2) 142.71(15)
P(4)-Pt(3)-Pt(2) 123.10(4)
P(2)-Pt(3)-P(4) 172.04(5)
1
the J P(3),H value can be calculated (360 Hz), and the 9
P(2)-Pt(3)-Pt(2)
Pt(2)-P(1)-Pt(1)
50.01(4)
78.74(4)
Hz splitting is due to coupling with P(1).
Pt(2)-P(2)-Pt(3)
78.78(4)
The 19F NMR spectrum of 1 shows six signals. Two
of them (2:2 intensity ratio) appear at low field (o-F
atoms) and show platinum satellites, while those ap-
pearing at higher field (1:1:2:2 intensity ratio) are
assigned to the two p-F atoms and to the m-F atoms of
the two C6F5 groups, respectively. This pattern confirms
that the C6F5 groups are inequivalent.
The 31P{1H} NMR spectrum shows three signals. The
signal due to the P atom of the phosphido group (P(1))
appears at 111.5 ppm, in the expected region for PPh2-
bridged metal-metal-bonded complexes.13 The signal
appears as a doublet (2J P(1),P(2) ) 305 Hz) flanked by
195Pt satellites (1J Pt(1,2),P(1) ) 1734, 2068 Hz). The signal
due to P(2) (PPh3 group) appears at 18.1 ppm as a
doublet (305 Hz) with one pair of platinum satellites,
1J Pt(2),P(2) ) 2636 Hz, coupling with Pt(1) not being
observed. The signal due to the P atom of the PPh2H
group (P(3)) appears as a singlet at -8.0 ppm. This
signal shows two pairs of platinum satellites (splittings
of 207 and 3996 Hz) due to coupling with Pt(1) and Pt-
(2), respectively.
trinuclear complex in which the three platinum atoms
are in a nonlinear array. As can be seen, two “(C6F5)-
(PPh3)Pt(PPh2)(H)” units are joined to another platinum
atom through the diphenylphosphido and hydride groups
that are acting as bridging ligands. The core of this
complex is essentially planar, since the three platinum
atoms, and the atoms directly bonded to them, lie in
the same plane. The total valence electron count for this
complex is 44, implying the presence of two metal-
metal bonds. This is confirmed by the X-ray study,
which shows Pt-Pt distances of 2.874(1) Å (Pt(1)-Pt-
(2)) and 2.852(1) Å (Pt(2)-Pt(3)), compatible with the
existence of intermetallic bonds. Both Pt(1) and Pt(3)
have the same four ligands completing a square-planar
coordination around the metal centers. Unfortunately,
the X-ray study did not give reliable information about
the position of the hydride ligands, but their presence
1
and structural role can be inferred from the H NMR
spectrum of 2 (see below). The available angles around
Pt(1) and Pt(3) reveal a typical square-planar configu-
ration for the metals. The P(1)-Pt(2)-P(2) angle has a
somewhat high value, 111.01(5)°. This fact is probably
related to the bent (146.84(1)°) Pt(1)-Pt(2)-Pt(3) unit
and may be due to the small size of the hydride ligands
located trans to the phosphido groups at Pt(2) and the
steric repulsion caused by the phosphido phenyl rings.
The Pt-P-Pt angles are small, Pt(1)-P(1)-Pt(2) )
78.74(4)° and Pt(2)-P(2)-Pt(3) ) 78.78(4)°, as previ-
The structure of 2 has been established by an X-ray
diffraction study (see Figure 1). Selected bond distances
and angles are listed in Table 1. The compound is a
(13) (a) Falvello, L. R.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Mart´ınez-
Sarin˜ena, A. P. Organometallics 1997, 16, 5849. (b) Alonso, E.; Fornie´s,
J .; Fortun˜o, C.; Mart´ın, A.; Orpen, A. G. Organometallics 2000, 19,
2690. (c) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Mart´ın, A.; Orpen, A. G.
J . Chem. Soc., Chem. Commun. 1996, 231.

Phosphido-Bridged Derivatives of Pt(I) and Pt(II)
Organometallics, Vol. 20, No. 5, 2001 853
ously observed in systems in which the phosphorus atom
bridges two metal centers joined by an intermetallic
bond.
1
The H NMR spectrum of 2 confirms the presence of
bridging hydride ligands. It contains a high-field reso-
nance centered at -5.6 ppm as a broad doublet (45 Hz).
1
The H{31P} NMR experiments show for this signal the
same broad doublet when the spectrum is measured
with P irradiation in the PPh3 region (ca. 20 ppm, see
below), while it shows a broad singlet when the spec-
trum is measured with P irradiation in the µ-PPh2
region (ca. 107 ppm, see below). Thus, the splitting of
1
the µ-hydride signal in the H NMR spectrum is due to
coupling with the P atom of the PPh2 group trans to
the hydride at Pt(2) (2J P,H ) 45 Hz). This value is
smaller than typical P-H couplings for tertiary phos-
phine complexes, but it is similar to that found in the
µ-phosphido complex [PtW2(µ-PPh2)2(µ-H)(µ-CO)Cp2-
(CO)4]+.14 The signal shows platinum satellites from
F igu r e 2. Structure of the complex [Pt2(µ-PPh2)(C6F5)-
(PPh3)3] (3). Thermal ellipsoids are drawn at the 50%
probability level.
1
which two values of J Pt,H can be measured, 442 and
508 Hz, in accord with the presence of a bridging
hydride.3c,8d,12
The 19F NMR spectrum of 2 exhibits only three
signals in a 2:1:2 intensity ratio, in agreement with the
presence of two equivalent C6F5 groups.
Sch em e 2
The 31P{1H} NMR spectrum of 2 is in agreement with
the trinuclear nature of the cluster. It shows signals due
to all six subspectra arising from the six different
isotopomeric combinations of platinum nuclei having
different nuclear spins (Pt/Pt/Pt 29.1%, 195Pt/Pt/Pt
29.6%, Pt/195Pt/Pt 14.8%, 195Pt/195Pt/Pt 15.1%, 195Pt/Pt/
195Pt 7.5%, and 195Pt/195Pt/195Pt 3.8%). The spectrum has
two sharp doublets (308 Hz) at 106.8 (µ-P) and 19.9
(PPh3) ppm. From the platinum satellites two values of
2
1J Pt,P (3195 and 1918 Hz) and one value of J Pt,P (132
Hz) can be extracted for the µ-PPh2 groups and one
1
2
value of J Pt,P and one of J Pt,P (2708 and 63 Hz,
respectively) for the PPh3 ligands.
As we have seen before, some dinuclear platinum
complexes with the Pt(µ-PPh2)(µ-H)Pt bridging system
have been reported but, as far as we know, complex 2
is the first trinuclear platinum complex in which the
three metal centers are linked by “Pt(µ-PPh2)(µ-H)Pt”
units. The formation of complex 2 seems to be the result
of the oxidative addition of the P-H bonds of the two
PPh2H ligands of the mononuclear starting material to
one Pt(0) center and the migration of the C6F5 groups
(see Scheme 2). In accord with this proposal, a similar
reaction using cis-[Pt(C6F5)2(PPh2H)2]/[Pt(C7H10)3]/PPh3
in a 1:2:2 molar ratio gives 2 in a better yield (48%).
Rea ction of cis-[P t(C6F 5)2(P P h 2H)2] w ith [P t-
(C7H10)3] a n d P P h 3 in a 1:1:2 Mola r Ra tio. When cis-
[Pt(C6F5)2(PPh2H)2] is added to a toluene solution of
[Pt(C7H10)3] and PPh3 in a 1:1:2 molar ratio (Scheme
1), the neutral dinuclear Pt(I) derivative [(C6F5)(PPh3)-
Pt(µ-PPh2)Pt(PPh3)2] (3) is isolated in 20% yield (based
on platinum) from the reaction mixture.
The structure of 3 has been established by a X-ray
diffraction study (see Figure 2). Selected bond distances
and angles are listed in Table 2. Compound 3 is a
dinuclear Pt(I) complex in which the platinum atoms
are bridged only by a diphenylphosphido ligand which
is trans to the only pentafluorophenyl group present in
the complex. The central core of the complex, formed
by the platinum and phosphorus atoms and C(1), is
almost perfectly planar. The Pt-Pt distance (2.781(1)
Å), which is slightly longer than those in complex 2,
(14) Braunstein, P.; De J esu´s, E.; Tiripicchio, A.; Ugozzoli, F. Inorg.
Chem. 1992, 31, 411.

854 Organometallics, Vol. 20, No. 5, 2001
Alonso et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [P t2(µ-P P h 2)(C6F 5)(P P h 3)3]‚1/2CH3C6H5
(3‚1/2CH3C6H5)
decrease of the formal oxidation state of the metal
center.9 The 19F NMR spectrum shows three signals in
a 2:2:1 intensity ratio due to o-F, m-F, and p-F atoms,
respectively. The 31P NMR spectrum of 3 shows four
signals due to the four inequivalent P atoms and is the
result of the superposition of four subspectra, arising
from the four different isotopomeric combinations of
platinum nuclei having different nuclear spins (Pt/Pt
43.9%, 195Pt/Pt 22.3%, Pt/195Pt 22.3%, and 195Pt/195Pt
11.4%). The signal due to the PPh2 ligand, P(1), appears
at low field, 150.8 ppm, as can be expected13 for a PPh2
ligand bridging two platinum atoms joined by a metal-
metal bond. The signal appears as a broad doublet due
to the coupling with the P(4) atom of the PPh3 ligand
in a trans position (2J P(1),P(4) ) 232 Hz) and to poorly
resolved coupling with P(2) or P(3). The signal due to
P(4) appears at 31.8 ppm as a doublet (232 Hz). The
resonances due to the PPh3 ligands cis to the PPh2
group, P(2) and P(3), show similar chemical shift signals
and can be analyzed as an AB spin system from which
values of δ(PA) (17.3 ppm), δ(PB) (23.1 ppm), and J AB
Pt(1)-P(1)
Pt(1)-Pt(2)
Pt(2)-P(2)
Pt(1)-P(3)
2.262(2)
2.7813(7)
2.260(3)
2.286(3)
Pt(2)-C(1)
Pt(1)-P(4)
Pt(2)-P(1)
2.098(8)
2.311(2)
2.223(2)
P(1)-Pt(1)-P(3)
P(3)-Pt(1)-P(4)
103.21(9)
105.09(10) P(1)-Pt(1)-Pt(2)
P(3)-Pt(1)-Pt(2) 154.20(7)
P(1)-Pt(1)-P(4)
150.47(9)
51.04(6)
P(4)-Pt(1)-Pt(2) 100.19(7)
C(1)-Pt(2)-P(1)
P(1)-Pt(2)-P(2)
P(1)-Pt(2)-Pt(1)
Pt(2)-P(1)-Pt(1)
160.8(3)
106.00(9)
52.31(6)
76.65(7)
C(1)-Pt(2)-P(2)
93.0(3)
C(1)-Pt(2)-Pt(1) 108.5(3)
P(2)-Pt(2)-Pt(1) 157.87(7)
confirms the existence of the expected intermetallic
bond. The environment of the platinum atoms deviates
strongly from square planar. Thus, the angles around
platinum are as follows: around Pt(1), P(1)-Pt(1)-P(3)
) 103.21(9)°, P(3)-Pt(1)-P(4) ) 105.09(10)°, and P(1)-
Pt(1)-P(4) ) 150.47(9)°; around Pt(2), P(1)-Pt(2)-P(2)
) 106.00(9)°, P(2)-Pt(2)-C(1) ) 93.0(3)°, and P(1)-Pt-
(2)-C(1) ) 160.8(3)°. These values are likely due to the
steric effects introduced by the presence of several bulky
PPh3 ligands around the platinum atoms and the
absence of a second bridging ligand. As for complex 2,
the Pt(1)-P(1)-Pt(2) angle has a small value, 76.65-
(7)°, in agreement with the existence of a Pt-Pt bond.
Complex 3 contains one phosphido ligand and only
one C6F5 group and may be the result of two oxidative
additions of P-H bonds to the Pt(0) derivative and
reductive elimination of C6F5H. The total valence elec-
tron count of 30 is consistent with the presence of a
platinum-platinum single bond, as confirmed by the
X-ray study. Dinuclear cationic complexes of Pd(I) of the
type [Pd2(µ-PR2)(PR′3)2LL′]+ in which the two metal
atoms are linked by both a metal-metal bond and a
single PR2 bridging ligand and in which a nearly linear
P-Pd-Pd-P arrangement is present have been de-
scribed.15 The syntheses of these complexes is achieved
by substitution processes from dinuclear phosphido
derivatives of Pd(I). The analogous complexes of Pt(I)
have not been described.
The stoichiometry of 3, which contains three PPh3
ligands, suggests that other compounds are formed in
the reaction. The 19F and 31P NMR spectra of the solid
obtained from mother liquors show that it contains a
mixture of products in which the starting material cis-
[Pt(C6F5)2(PPh2H)2], [(C6F5)(PPh3)Pt(µ-PPh2)Pt(PPh3)2]
(3), [(C6F5)2Pt(µ-PPh2)(µ-H)Pt(PPh3)2] (4), and [(C6F5)-
(PPh3)Pt(µ-PPh2)2Pt(H)(PPh3)] (5) (see below) can be
identified.
The IR spectrum of 3 shows one absorption in the
X-sensitive region of the C6F5 group. The absorption of
the pentafluorophenyl group, which is usually located
at ca. 950 cm-1, is shifted toward lower wavenumber,
945 cm-1, relative to its position in the platinum(II)
starting material, 951 cm-1, as expected, due to the
3
(199 Hz) can be calculated. The J P(2),P(3) value, 199 Hz,
3
is in the range found for J P,P in dinuclear palladium-
(I)15b-d or platinum(I)16 complexes which have a linear
P-M-M-P arrangement. Moreover, signals due to PA
appear as doublets (25 Hz) due to coupling with P(1).
The assignment of PA to P(2) or P(3) cannot be made
unambiguously. All signals show platinum satellites,
from which the values of J Pt,P can be extracted (see the
Experimental Section). It is noteworthy that in complex
3 the Pt(1)-P(4) distance (2.311(2) Å) is the longest
while the value of the coupling constant between Pt(1)
and P(4) is the highest (3443 Hz). Moreover, the signal
1
of P(1) shows that J Pt(1),P(1) is nearly equal to 1J Pt(2),P(1)
while the trans groups P(4)Ph3 and C6F5, respectively,
are different, as are the two Pt-P(1) distances, 2.262-
(2) and 2.223(2) Å. As we have shown previously,13 it is
necessary to be cautious about the structural informa-
1
tion which can be deduced from J Pt,P values.
Rea ction of cis-[P t(C6F 5)2(P P h 2H)2] w ith [P t-
(C7H10)3] a n d P P h 3 in a 1:1:3 Mola r Ra tio. To try a
more rational synthesis of 3, we carried out the reaction
in the presence of 3 equiv of PPh3. In this process a very
small amount of an insoluble red solid, not containing
C6F5, was crystallized and identified by its 31P NMR
spectrum as the dinuclear platinum(I) complex [Pt2(µ-
PPh2)2(PPh3)2].17 Complex 3 was isolated from the
solution, although the yield was not much better (22%).
From the mother liquors a complex mixture of products
was obtained. The 19F and 31P NMR spectra indicate
that cis-[Pt(C6F5)2(PPh2H)2], 3, and 5 are present in the
mixture.
Syn th eses of [(C6F 5)(P P h 3)P t(µ-P P h 2)P t(P P h 3)2]
(3), [(C6F 5)2P t (µ-P P h 2)(µ-H )P t (P P h 3)2] (4), a n d
[(C6F 5)(P P h 3)P t(µ-P P h 2)2P t(H)(P P h 3)] (5). Complex
3 contains only one PPh2 bridging group, and it does
not contain any PPh2H ligand; therefore, in order to
improve the yield of 3, we carried out the reaction of a
(15) (a) Leoni, P.; Pasquali, M.; Sommovigo, M.; Laschi, F.; Zanello,
P.; Albinati, A.; Lianza, F.; Pregosin, P. S.; Ruegger, H. Organometallics
1993, 12, 1702. (b) Leoni. P.; Pasquali, M.; Sommovigo, M.; Albinati,
A.; Pregosin, P. S.; Ruegger, H. Organometallics 1996, 15, 2047. (c)
Leoni, P.; Pieri, G.; Pasquali, M. J . Chem. Soc., Dalton Trans. 1998,
657. (d) Leoni, P.; Papucci, S.; Pasquali, M. Inorg. Chim. Acta 1999,
284, 246. (e) Leoni, P.; Pasquali, M.; Sommovigo, M.; Laschi, F.; Zanello,
P.; Albinati, A.; Lianza, F.; Pregosin, P. S.; Ruegger, H. Organometallics
1994, 13, 4017.
(16) (a) Hunt, C. T.; Matson, G. B.; Balch, A. L. Inorg. Chem. 1981,
20, 2270. (b) Ma, E.; Semelhago, G.; Walker, A.; Farrar, D. H.;
Gukathasan, R. R. J . Chem. Soc., Dalton Trans. 1985, 2595. (c) Uso´n,
R.; Fornie´s, J .; Espinet, P.; Fortun˜o, C.; Toma´s, M.; Welch, A. J . J .
Chem. Soc., Dalton Trans. 1989, 1583.
(17) Bender, R.; Bouaoud, S.-E.; Braunstein, P.; Dusausoy, Y.;
Merabet, N.; Raya, J .; Rouag, D. J . Chem. Soc., Dalton Trans. 1999,
735.

Phosphido-Bridged Derivatives of Pt(I) and Pt(II)
Organometallics, Vol. 20, No. 5, 2001 855
toluene solution of cis-[Pt(C6F5)2(thf)2] and PPh2H (mo-
lar ratio 1:1) with a toluene solution of [Pt(C7H10)3] and
PPh3 (1:3 molar ratio). Complex 3 was obtained in
slightly better yield (37%).
As we have noted before, in the reactions that afford
3 a mixture of products is also obtained in which
complexes 4 and 5 can be identified. Both complexes can
be obtained by reasonable synthetic routes from com-
plexes 1 and 3, respectively. When PPh3 is added to a
solution of 1 in toluene, substitution of the PPh2H ligand
takes place and the dinuclear complex [(C6F5)2Pt(µ-
PPh2)(µ-H)Pt(PPh3)2] (4) is obtained. As expected, the
IR spectrum of 4 shows two absorptions of equal
intensity in the 800 cm-1 region (due to the X-sensitive
mode9 of the C6F5 groups). The 1H NMR spectrum shows
a signal at -6.5 ppm, due to the hydride ligand, as a
broad doublet, with splitting (80 Hz) due to the phos-
phorus atom of the PPh3 group trans to the hydride
ligand (P(3)). The signal shows platinum satellites from
which two values of 1J Pt,H can be extracted, 520 and 412
Hz, in the range found for bridging hydrides. The 19F
and 31P NMR spectra of 4 are analogous to those for
complex 1, and all data are given in the Experimental
Section. Aiming to try a more direct synthesis of 4, we
prepared the mononuclear platinum(II) derivative cis-
[Pt(C6F5)2(PPh2H)(PPh3)] in order to study its reaction
with [Pt(C7H10)3] and PPh3. However, when cis-[Pt-
(C6F5)2(PPh2H)(PPh3)] is added to toluene solutions of
[Pt(C7H10)3] and PPh3 in 1:1:1 molar ratio under the
same reaction conditions (20 h at room temperature),
complex 4 is not obtained and the starting material cis-
[Pt(C6F5)2(PPh2H)(PPh3)] is recovered from solution.
With the aim of establishing whether the dinuclear
platinum(I) complex 3 is obtained from the dinuclear
platinum(II) complex 4, which contains both phosphido
and hydride ligands, we carried out the reaction of
complex 1 with 3 equiv of PPh3. The solid obtained from
the solution does not contain the diplatinum(I) complex
3 (by NMR spectroscopy), thus indicating that complex
3 is not formed from 1 (or 4) through a reductive
elimination of C6F5H and addition of PPh3.
F igu r e 3. (a) Structure of the complex [Pt2H(C6F5)(µ-
PPh2)2(PPh3)2] (5). Thermal ellipsoids are drawn at the 50%
probability level. (b) Core of complex 5 showing its bent
disposition.
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [P t2H(C6F 5)(µ-P P h 2)2(P P h 3)2] (5)
Pt(1)-C(1)
Pt(1)-P(2)
Pt(2)-P(2)
Pt(1)-P(4)
2.073(9)
2.352(2)
2.364(2)
2.326(2)
Pt(2)-P(3)
Pt(2)-H(1)
Pt(1)-P(1)
Pt(2)-P(1)
2.291(3)
1.71(9)
2.334(2)
2.316(2)
C(1)-Pt(1)-P(4)
P(4)-Pt(1)-P(1)
P(4)-Pt(1)-P(2)
P(3)-Pt(2)-P(1)
P(1)-Pt(2)-P(2)
P(2)-Pt(2)-H(1)
Pt(2)-P(1)-Pt(1)
88.7(2)
98.54(8)
167.99(8)
176.92(8)
75.62(8)
162(3)
C(1)-Pt(1)-P(1)
C(1)-Pt(1)-P(2)
P(1)-Pt(1)-P(2)
P(3)-Pt(2)-P(2)
P(1)-Pt(2)-H(1)
P(3)-Pt(2)-H(1)
Pt(1)-P(2)-Pt(2)
172.5(2)
97.7(2)
75.50(8)
106.17(8)
89(3)
When PPh2H is added to a solution of the platinum-
(I) derivative 3, the dinuclear Pt(II) complex [(C6F5)-
(PPh3)Pt(µ-PPh2)2Pt(H)(PPh3)] (5), which contains one
terminal hydride and two PPh2 bridging ligands, can
be isolated.
89(3)
95.77(8)
97.55(9)
ideal. In accordance with this, the Pt(1)-P(1)-Pt(2) and
Pt(1)-P(2)-Pt(2) angles are larger (97.55(9) and 95.77-
(8)°, respectively) than for 2 and 3 (see Tables 1 and 2),
in which Pt-Pt bonds are present. Another substantial
difference between complexes 2 and 3 and complex 5 is
that, whereas the former are basically planar, 5 has a
folded core (Figure 3b), with the dihedral angle between
the coordination planes of the Pt atoms being 136.2°.
The structure of 5 was established by a X-ray diffrac-
tion study (see Figure 3). Selected bond distances and
angles are listed in Table 3. Compound 5 is a dinuclear
Pt(II) complex in which the platinum centers are
bridged by phosphido ligands and the two terminal PPh3
ligands are mutually transoid. The Pt‚‚‚Pt distance is
3.498(1) Å, which precludes any intermetallic bond, as
expected for a total valence electron count skeleton of
32. In this case, it has been possible to locate the hydride
ligand by using the program HYDEX18 and, subse-
quently, to refine its position against the X-ray data.
The square-planar environments of Pt(1) and Pt(2) are
slightly distorted, since, as observed in other poly-
nuclear Pt(II) complexes with no metal-metal bonds
and diphenylphosphido bridging ligands, the P(1)-Pt-
(1)-P(2) and P(1)-Pt(2)-P(2) angles are slightly more
acute (75.50(8) and 75.62(8)°, respectively) than the
The IR spectrum of 5 shows one absorption at 2038
cm-1, in accord with the presence of a terminal Pt-H
moiety.8d,10a Usually the ν(Pt-H) stretching mode for
this type of hydride is in the range 1970-2250 cm-1
,
whereas the ν(P-H) stretching mode in coordinated
PPh2H complexes appears at higher wavenumber (2329
cm-1 for cis-[Pt(C6F5)2(PPh2H)2]5 and 2320 cm-1 for 1).
There is one absorption in the 800 cm-1 region due to
the X-sensitive mode of the C6F5 group. The correspond-
ing absorption at 945 cm-1 in the starting material 3 is
shifted to higher wavenumber in 5, 952 cm-1, in
(18) Orpen, A. G. J . Chem. Soc., Dalton Trans. 1980, 2509.

856 Organometallics, Vol. 20, No. 5, 2001
Alonso et al.
agreement with the increase of the formal oxidation
state of the platinum centers.9
The H NMR spectrum of 5 shows a signal centered
complex 5 in toluene was heated to 40 °C for 3 h. No
changes were detected in the solution, and complex 5
was recovered. Under these conditions complex 5 does
not eliminate C6F5H to afford the well-known dinuclear
platinum(I) compound [Pt2(µ-PPh2)2(PPh3)2]. Similarly,
[Pt2(µ-PBut ) (H)2(PBut H)2] does not eliminate hydro-
1
at -5.6 ppm due to the hydride ligand. The signal is a
doublet of broad multiplets due to the coupling with the
P(2) of the PPh2 group trans to the hydride ligand and
to the two P atoms cis to the hydride. When the
spectrum is measured with phosphorus decoupling in
the PPh3 region, the signal of the hydride ligand appears
as a doublet of doublets, 148 and 16 Hz, with the large
splitting due to P(2) and the smaller one due to the P
atom of the cis µ-PPh2 group, P(1). When the spectrum
is measured with phosphorus decoupling in the diphe-
nylphosphide region, the coupling with the PPh3 ligand,
P(3), is not well-resolved and the signal appears as a
broad singlet. In all cases the signal shows platinum
2 2
2
gen to yield [Pt2(µ-PBut ) (PBut H)2].
8d,10b
2 2
2
Rea ction of 3 w ith CO. To establish that the PPh3
ligand trans to PPh2 in the neutral Pt(I) derivative 3
may be easily substituted, we studied the reaction of 3
with CO. When CO is bubbled through an orange
solution of 3 in CH2Cl2, the solution fades to yellow.
After addition of n-hexane with further bubbling of CO,
the yellow monocarbonyl derivative [(C6F5)(PPh3)Pt(µ-
PPh2)Pt(PPh3)(CO)] (6) is obtained. Nevertheless, if the
yellow CH2Cl2 solution is evaporated under vacuum, the
solution turns orange again and only the starting
material can be crystallized, thus indicating the revers-
ibility of the substitution process. The IR spectrum of 6
shows a strong absorption at 2039 cm-1, due to ν(CO).
This value is similar to those observed for other plati-
num(I) carbonyl derivatives, and it denotes some degree
of π-back-donation in the PtI-CO bond. The absorptions
due to the C6F5 group are analogous to those found for
this group in complex 3. The 19F NMR spectrum of 6
shows three signals in a 2:2:1 intensity ratio, as
expected, and the 31P NMR spectrum displays three
signals due to the three inequivalent P atoms. The
signal due to the PPh2 group (single bridging ligand
between two platinum atoms joined by a metal-metal
bond) appears at 136.5 ppm as a broad singlet. The
signals due to the P atoms of the two inequivalent PPh3
ligands appear at 27.2 and 18.9 ppm as two broad
doublets, the splitting being due to the coupling of both
P atoms (3J P,P ) 119 Hz). The three signals show
platinum satellites, and two values of 1J Pt,P for the PPh2
1
satellites from which the J Pt,H value can be calculated,
1038 Hz. The value of coupling constant between
2
hydride ligand and the trans P atom, J P(2),H ) 148 Hz,
1
as well as the J Pt,H value are larger than those found
2
1
for J P(trans to H),H and J Pt,H in complexes 1, 2, and 4, in
agreement with the presence of a terminal hydride
ligand in 5.3c,8d,12 The 19F NMR spectrum is similar to
that for 3, as expected.
The 31P NMR spectrum of 5 shows signals in two very
different regions. The signals due to the two inequiva-
lent PPh3 groups appear centered at 21.3 and 31.1 ppm.
Both are doublets (297 and 292 Hz, respectively) by
coupling with the trans-PPh2 group and show platinum
1
satellites from which the J Pt,P values can be extracted,
2175 and 2394 Hz, respectively. The signals due to the
two inequivalent diphenylphosphido ligands are both in
the -105 ppm region and show a very complex pattern.
Each of these two P atoms is coupled with one trans-
PPh3 ligand. For a structure, such as 5, in which the
two PPh2 groups in a dinuclear complex are inequiva-
lent, the coupling between the two cis P atoms is large.19
Moreover, the two platinum atoms in 5 are inequivalent,
so that each signal shows platinum satellites with
different splittings. All these couplings make a very
complex pattern of signals and prevent a reliable
assignment. The chemical shift is in the region expected
for two PPh2 groups that are acting as bridging ligands
between two platinum centers not joined by a metal-
metal bond.5,20
1
signal and one value of J Pt,P for each PPh3 signal can
be calculated. Moreover, in the signals due to the PPh3
ligands, a pair of close platinum satellites are observed
2
for each, so that the values of J Pt,P can be extracted.
The presence of a platinum-platinum bond in 6 (total
valence electron count 30) is supported by the δ(P) value
of the PPh2 group (136.5 ppm), by the coupling observed
between the two P atoms of the PPh3 ligands (3J P,P
119 Hz), and by the observed values of J Pt,P, 262 and
)
2
363 Hz.
The formation of 5 from complex 3 (a Pt(I)-Pt(I)
derivative) is formally the result of the oxidative addi-
tion of PPh2H to the dinuclear compound 3, with
concomitant elimination of PPh3. Some dinuclear cat-
ionic phosphido complexes of Pd(I) with coordinated
Con clu d in g Rem a r k s
The reaction that affords 1 from cis-[Pt(C6F5)2-
(PPh2H)2] with [Pt(C7H10)3] in the presence of 1 equiv
of PPh3 can be viewed as an oxidative addition of one
P-H bond to a platinum(0) center, giving rise to a
dinuclear derivative containing both a phosphido and
a hydrido ligand, and a migration of the PPh2H ligand
from one platinum center to the other. The trinuclear
complex 2 is formed as result of a double oxidative
addition of cis-[Pt(C6F5)2(PPh2H)2] to 2 equiv of the
zerovalent platinum derivative (Scheme 2). Neverthe-
less, the reaction with 2 or 3 equiv of PPh3 seems to be
more complex and it could be the result of several
reaction paths. (a) The initial formation of complex 1
and its reaction with one PPh3 ligand occurs, giving rise
to complex 4. (b) PPh2H adds oxidatively to the di-
nuclear Pt(I) derivative 3, leading to formation of
secondary phosphine are known, [Pd2(µ-PBut )L2-
2
(PR2H)2]+ (L ) CO, R ) But;15a L ) PR2H, R ) Cy15e).
Usually these complexes do not undergo oxidative
addition of a P-H bond to a palladium center to afford
palladium(II) complexes. In our case the P-H addition
may be favored by both the neutrality of the intermedi-
ate and the higher stability of the Pt-H bond versus
Pd-H.
Complex 5 contains both a C6F5 and a hydride ligand.
To study the stability of this complex, a solution of
(19) Falvello, L. R.; Fornie´s, J .; Fortun˜o, C.; Mart´ınez, F. Inorg.
Chem. 1994, 33, 6246.
(20) Alonso, E.; Fornie´s, J .; Fortun˜o, C.; Toma´s, M. J . Chem. Soc.,
Dalton Trans. 1995, 3777.

Phosphido-Bridged Derivatives of Pt(I) and Pt(II)
Organometallics, Vol. 20, No. 5, 2001 857
(b) 1:1:2 Mola r Ra tio. To a toluene solution (8 mL) of PPh3
(0.087 g, 0.332 mmol) was added [Pt(C7H10)3] (0.079 g, 0.165
mmol). After 10 min of stirring, cis-[Pt(C6F5)2(PPh2H)2] (0.149
g, 0.165 mmol) was added and the solution was stirred for 20
h at room temperature. The solution was evaporated to ca. 1
mL, and Et2O (6 mL) was added. The resulting yellow solid 3
was filtered off and washed with 3 × 0.5 mL of Et2O (0.050 g,
20%). Anal. Found (calcd) for C72F5H55P4Pt2: C, 56.3 (56.55);
H, 3.8 (3.6). IR (Nujol, C6F5): 945 cm-1; 770 cm-1 (X-sensitive9).
complex 5. (c) A reaction path of uncertain type leads
to 3. The oxidative addition of a P-H bond (of the
mononuclear Pt(II) starting material) to the platinum-
(0) center, giving rise to the “(C6F5)2Pt(µ-PPh2)(µ-H)Pt”
fragment, as in the formation of 1, can be ruled out,
since complex 4 does not react with PPh3 to give 3. (d)
The dinuclear platinum(I) complex [Pt2(µ-PPh2)2(PPh3)2]
forms at room temperature but does not result from
C6F5H elimination from the dinuclear platinum(II)
complex 5. It is noteworthy that [Pt2(µ-PPh2)2(PPh3)2]
has been reported as a product of thermolysis of
platinum(0) complexes, such as [Pt(PPh3)4] in benzene
and [Pt(C2H4)(PPh3)2] in acetone, and that the condi-
tions required to form it are critical.17,21
3
19F NMR (298 K, CDCl3, 282.4 MHz; δ): -112.2 (2 o-F, J Pt,F
) 367.1 Hz), -165.8 (2 m-F), -168.7 (1 p-F) ppm. 31P NMR
2
(298 K, CDCl3, 121.4 MHz; δ): 150.8 (broad d, P(1), J P(1),P(4)
1
) 232 Hz, J Pt(1),P(1)
≈
1J Pt(2),P(1) ) 2767 Hz), 31.8 (d, P(4),
2J P(1),P(4) ) 232 Hz, J Pt(1),P(4) ) 3443 Hz), 17.3 (PA, J P(2),P(3)
199 Hz, J P(1),P(A) ) 25 Hz, J Pt,P(A) ) 3240 Hz, J Pt,P(A) ) 449
Hz), 23.1 (PB, J P(2),P(3) ) 199 Hz, J Pt,P(B) ) 2997 Hz, J Pt,P(B)
)
1
3
2
1
2
3
1
2
)
605 Hz) ppm. The filtrate of 3 was evaporated to dryness, and
the residue was washed with hexane. This yellow solid is a
mixture of complexes in which the starting material cis-[Pt-
(C6F5)2(PPh2H)2], complex 3, complex 4, and complex 5 can be
detected (NMR spectroscopy).
Exp er im en ta l Section
Gen er a l Da ta . All reactions were carried out under a
nitrogen atmosphere. Literature methods were used to prepare
the starting complexes cis-[Pt(C6F5)2(PPh2H)2]5 and [Pt-
(C7H10)3].22 C and H analyses were performed with a Perkin-
Elmer 240B microanalyzer. IR spectra were recorded on a
Perkin-Elmer 599 spectrophotometer (Nujol mulls between
polyethylene plates in the range 4000-200 cm-1). NMR spectra
were recorded on a Varian Unity 300 instrument with SiMe4,
CFCl3, and 85% H3PO4 as external references for 1H, 19F, and
31P, respectively.
(c) 1:1:3 Mola r Ra tio. To a toluene solution (10 mL) of PPh3
(0.130 g, 0.496 mmol) was added [Pt(C7H10)3] (0.079 g, 0.165
mmol). After 10 min of stirring, cis-[Pt(C6F5)2(PPh2H)2] (0.149
g, 0.165 mmol) was added and the solution was stirred at room
temperature for 22 h. A red solid was filtered off and washed
with 3 × 0.5 mL of toluene (0.014 g). This compound was
identified (31P NMR, CD2Cl2) as [Pt2(µ-PPh2)2(PPh3)2].17 The
toluene solution was evaporated to ca. 1 mL, and Et2O (10 mL)
was added. The yellow solid 3 thus obtained was filtered off
and washed with 3 × 0.5 mL of Et2O (0.056 g, 22%). The
filtrate of 3 was evaporated to ca. 1 mL, hexane (10 mL) was
added, and the yellow solid thus obtained (0.070 g) was filtered
off and washed with hexane (3 mL). This yellow solid is (NMR
spectroscopy) essentially the starting material cis-[Pt(C6F5)2-
(PPh2H)2, together with other complexes, among which com-
plex 3 and complex 5 can be identified.
P r ep a r a tion of [{(C6F 5)(P P h 3)P t(µ-P P h 2)(µ-H)}2P t] (2).
To a toluene solution (10 mL) of PPh3 (0.058 g, 0.220 mmol)
and [Pt(C7H10)3] (0.105 g, 0.220 mmol) was added cis-[Pt(C6F5)2-
(PPh2H)2] (0.099 g, 0.110 mmol). After 20 h of stirring at room
temperature the solution was evaporated to dryness, acetone
(3 mL) was added, and a very pale yellow solid crystallized. 3
was filtered off and washed with 3 × 1 mL of acetone (0.097
g, 48%).
P r ep a r a tion of [(C6F 5)(P P h 3)P t(µ-P P h 2)P t(P P h 3)2] (3).
To a toluene solution (5 mL) of PPh3 (0.176 g, 0.671 mmol)
and [Pt(C7H10)3] (0.107 g, 0.224 mmol) was added a solution
of cis-[Pt(C6F5)2(thf)2] (0.150 g, 0.223 mmol) and PPh2H (39
µL, 0.224 mmol) in toluene (10 mL). After 23 h of stirring at
room temperature the solution was evaporated almost to
dryness. Et2O (5 mL) was added, and the yellow solid 3 was
filtered off and washed with 3 × 1 mL of Et2O (0.125 g, 37%).
P r ep a r a tion of [(C6F 5)2P t(µ-P P h 2)(µ-H)P t(P P h 3)2] (4).
To a toluene (5 mL) solution of 1 (0.060 g, 0.044 mmol) was
added PPh3 (0.012 g, 0.046 mmol). The solution was stirred
for 1 h and evaporated to dryness. The oily residue was treated
with hexane (10 mL), and by stirring a pale yellow solid was
formed, which was filtered off and washed with 2 mL of hexane
(0.039 g, 62%). The solid thus obtained is complex 4 together
with a minor amount of starting material. Pure sample of 4 is
obtained as pale yellow crystals by diffusion of hexane into
CH2Cl2 solutions. Anal. Found (calcd) for C60F10H41P3Pt2: C,
50.4 (50.2); H, 2.7 (2.9). IR (Nujol): 791, 782 cm-1 (X-sensitive,
Rea ction of cis-[P t(C6F 5)2(P P h 2H)2] w ith [P t(C7H10)3]
a n d P P h 3. (a ) 1:1:1 Mola r Ra tio. To a toluene solution (10
mL) of PPh3 (0.117 g, 0.446 mmol) was added [Pt(C7H10)3]
(0.213 g, 0.446 mmol). After 10 min of stirring, cis-[Pt(C6F5)2-
(PPh2H)2] (0.402 g, 0.446 mmol) was added and the solution
was stirred for 20 h at room temperature. The resulting
solution was evaporated almost to dryness, and the residue
was treated with a mixture of hexane (20 mL) and Et2O (10
mL). The very pale yellow solid 1 crystallized, which was
filtered off and washed with 2 × 0.5 mL of cold Et2O (0.220 g,
36%). Anal. Found (calcd) for C54F10H37P3Pt2: C, 47.45 (47.7);
H, 2.4 (2.7). IR (Nujol): 790, 780 cm-1 (X-sensitive,9 C6F5); 2320
cm-1 (ν(P-H)). 1H NMR (298 K, CDCl3, 300 MHz; δ): 6.8
1
3
2
(PPh2H, J P(3),H ) 360 Hz, J P(1),H ) 9 Hz, J Pt(2),H ) 41 Hz),
2
1
1
-6.0 (µ-H, J P(3),H ) 81 Hz, J Pt(1),H ) 430 Hz, J Pt(2),H ) 537
Hz) ppm. 19F NMR (298 K, CDCl3, 282.4 MHz; δ): -116.9 (2
o-F, 3J Pt,F ) 281.5 Hz), -117.9 (2 o-F, 3J Pt,F ) 405.8 Hz), -162.8
(1 p-F), -164.3 (1 p-F), -164.8 (2 m-F), -165.7 (2 m-F) ppm.
31P NMR (298 K, CDCl3, 121.4 MHz; δ): 111.5 (d, P(1), 2J P(1),P(2)
1
2
) 305 Hz, J Pt(1,2),P(1) ) 1734, 2068 Hz), 18.1 (d, P(2), J P(1),P(2)
) 305 Hz, 1J Pt(2),P(2) ) 2636 Hz), -8.0 (s, P(3), 1J Pt(2),P(3) ) 3996
2
Hz, J Pt(1),P(3) ) 207 Hz) ppm. The mother liquors of 1 were
evaporated to dryness, and the residue was treated with a
mixture of acetone (8 mL) and i-PrOH (2 mL) and left in the
freezer for 3 days. The very pale yellow solid 2 crystallized,
which was filtered off and washed with 4 × 0.5 mL of acetone
(0.084 g, 21% based on [Pt(C7H10)3]). Anal. Found (calcd) for
C
72F10H52P4Pt3: C, 47.9 (47.6); H, 2.8 (2.9). IR (Nujol): 793,
784 cm-1 (X-sensitive,9 C6F5). 1H NMR (298 K, CDCl3, 300
2
1
1
MHz; δ): -5.6 (µ-H, J P(trans),H ) 45 Hz, J Pt,H ) 442 Hz, J Pt,H
) 508 Hz) ppm. 19F NMR (298 K, CDCl3, 282.4 MHz; δ): -117.6
(2 o-F, 3J Pt,F ) 376.1 Hz), -164.6 (1 p-F), -165.6 (2 m-F) ppm.
31P NMR (298 K, CDCl3, 121.4 MHz; δ): 106.8 (sharp d, PPh2,
1
2
2J P,P(trans) ) 308 Hz, J Pt,P ) 3195 and 1918 Hz, J Pt,P ) 132
Hz), 19.9 (sharp d, PPh3, 2J P,P(trans) ) 308 Hz, 1J Pt,P ) 2708 Hz,
2J Pt,P ) 63 Hz) ppm.
C6F5). 1H NMR (298 K, CDCl3, 300 MHz; δ): -6.5 (2J P(3),H
)
1
1
80 Hz, J Pt(1),H ) 412 Hz, J Pt(2),H ) 520 Hz) ppm. 19F NMR
(21) (a) Bennett, M. A.; Berry, D. E.; Dirnberger, T.; Hockless, D.
C. R.; Wenger, E. J . Chem. Soc., Dalton Trans. 1998, 2367. (b) Taylor,
N. J .; Chieh, P. C.; Carty, A. J . J . Chem. Soc., Chem. Commun. 1975,
448. (c) Bender, R.; Braunstein, P.; Dedieu, A.; Ellis, P. D.; Higgins,
B.; Harvey, P. D.; Sappa, E.; Tiripicchio, A. Inorg. Chem. 1996, 35,
1223.
3
(298 K, CDCl3, 282.4 MHz; δ): -117.1 (2 o-F, J Pt,F ) 283.7
3
Hz), -118.0 (2 o-F, J Pt,F ) 398.2 Hz), -163.7 (1 p-F), -164.4
(1 p-F), -164.8 (2 m-F), -165.6 (2 m-F) ppm. 31P NMR (298
2
K, CDCl3, 121.4 MHz; δ): 108.1 (d, P(1), J P(1),P(2) ) 294 Hz,
(22) Crascall, L. E.; Spencer, J . L. Inorg. Synth. 1990, 28, 126.
1J Pt(1,2),P(1) ) 1863, 2022 Hz), 20.2 (s, P(3), 1J Pt(2),P(3) ) 4214 Hz,

858 Organometallics, Vol. 20, No. 5, 2001
Alonso et al.
Ta ble 4. Cr ysta l Da ta a n d Str u ctu r e Refin em en t Deta ils for [{(C6F 5)(P P h 3)P t(µ-P P h 2)(µ-H)}2P t]‚C6H12‚3/
8C6H14 (2‚C6H12‚3/8C6H14), [(C6F 5)(P P h 3)P t(µ-P P h 2)P t(P P h 3)2]‚1/2C7H8 (3‚1/2C7H8), a n d
[(C6F 5)(P P h 3)P t(µ-P P h 2)2P t(H)(P P h 3)] (5)
2‚C6H12‚3/8C6H14
3‚1/2C7H8
5
empirical formula
unit cell dimens
a (Å)
b (Å)
c (Å)
C
72H52F10P4Pt3‚C6H12‚3/8C6H14
C72H55F5P4Pt2‚1/2C7H8
C66H51F5P4Pt2
20.0988(8)
20.6592(8)
18.5612(7)
90
99.7940(10)
90
7594.8(5); 4
0.710 73
173(1)
13.088(2)
14.003(2)
19.100(3)
92.700(12)
104.261(11)
107.604(11)
3205.7(8); 2
0.710 73
293(1)
21.606(2)
13.364(3)
21.930(4)
90
118.238(9)
90
5578(2); 4
0.710 73
173(1)
R (deg)
â (deg)
γ (deg)
V (Å3); Z
wavelength (Å)
temp (K)
radiation
cryst syst
graphite-monochromated Mo KR
monoclinic
triclinic
monoclinic
space group
crystal dimensions (mm)
P21/c
P1h
P21/c
0.16 × 0.13 × 0.10
0.50 × 0.40 × 0.10
0.50 × 0.40 × 0.30
abs coeff (mm-1
)
5.663
4.517
5.183
transmission factors
abs cor
diffractometer
2θ range for data collecn (deg)
no. of rflns collected
no. of indep rflns
refinement method
goodness of fit on F2
final R indices (I > 2σ(I))a
R indices (all data)
1.956, 1.222
0.932, 0.435
ψ scans
Siemens P3m
3.0-50.0 ((h, (k, +l)
11 524
0.791, 0.358
30 086 equiv rflns
Bruker SMART
2.1-50.0 ((h, (k, (l)
42 936
1940 equiv rflns
Siemens SMART
3.7-46.5 ((h, (k, (l)
22 903
13 398 (R(int) ) 0.0372)
11 014 (R(int) ) 0.0370)
full-matrix least squares on F2
1.007
7983 (R(int) ) 0.0878)
1.016
1.320
R1 ) 0.0293, wR2 ) 0.0692
R1 ) 0.0480, wR2 ) 0.0752
R1 ) 0.0480, wR2 ) 0.1270
R1 ) 0.0787, wR2 ) 0.0787
R1 ) 0.0514, wR2 ) 0.0979
R1 ) 0.0716, wR2 ) 0.1094
wR2 ) [∑w(Fo - Fc2)2/∑wFo
]
; R1 ) ∑||Fo| - |Fc||/∑|Fo|.
a
2
4
0.5
2
1
2J Pt(1),P(3) ) 225 Hz), 18.6 (d, P(2), J P(1),P(2) ) 294 Hz, J Pt(2),P(2)
) 2568 Hz, J Pt(1),P(2) ) 32 Hz) ppm.
unit cell dimensions were initially determined from the
positions of 267 reflections in 90 intensity frames measured
at 0.3° intervals in ω and subsequently refined on the basis of
positions of 4932 reflections from the main data set. An
absorption correction was applied on the basis of 30 086
symmetry-equivalent reflection intensities. For 3, unit cell
dimensions were determined from 35 centered reflections in
the range 15.1 < 2θ < 28.9°. An absorption correction was
applied on the basis of 420 azimuthal scan data. For 5, unit
cell dimensions were initially determined from the positions
of 259 reflections in 90 intensity frames measured at 0.3°
intervals in ω and subsequently refined on the basis of
positions of 5556 reflections from the main data set. An
absorption correction was applied on the basis of 1940 sym-
metry-equivalent reflection intensities. Lorentz and polariza-
tion corrections were applied for all the structures.
The structures were solved by Patterson and Fourier
methods. All refinements were carried out using the program
SHELXL-9323 or SHELXL-97.24 All non-hydrogen atoms were
assigned anisotropic displacement parameters and refined
without positional constraints, except as noted below. All
hydrogen atoms were constrained to idealized geometries and
assigned isotropic displacement parameters 1.2 times the Uiso
value of their attached carbon atoms (1.5 times for methyl
hydrogen atoms). For 2, the asymmetric unit contains three
half-molecules of cyclohexane (which were refined with oc-
cupancy 1, 0.75 and 0.25) and one half-molecule of n-hexane
(refined with occupancy 0.75). The geometric parameters of
these solvent molecules were restrained to idealized values.
For 3, in the final stages of the resolution the presence of
toluene as crystallization solvent was observed. The toluene
molecule lies astride an inversion center, so that only three of
the ring carbon atoms are present in the asymmetric unit, the
rest being generated by the symmetry operator. The structural
parameters in the toluene molecule were restrained using
DFIX and FLAT instructions. The attempts to locate the
methyl group of the solvent in the Fourier density maps were
2
[(C6F 5)(P P h 3)P t(µ-P P h 2)2P tH(P P h 3)] (5). To a toluene (15
mL) solution of 3 (0.100 g, 0.065 mmol) was added PPh2H (13.5
µL, 0.077 mmol). The solution was stirred at room temperature
for 20 h and then evaporated almost to dryness. Et2O (6 mL)
was added, and the yellow solid 5 was filtered off and washed
with 3 × 1 mL of Et2O (0.030 g, 32%). Anal. Found (calcd) for
C
66F5H51P4Pt2: C, 54.3 (54.55); H, 3.3 (3.5). IR (Nujol): 952
cm-1; 781 cm-1 (X-sensitive, C6F5); 2038 cm-1 (ν(Pt-H)). 1H
NMR (298 K, CDCl3, 300 MHz; δ): -5.6 (2J P(2),H ) 148 Hz,
1
2J P(1),H ) 16 Hz, J Pt(2),H ) 1038 Hz) ppm. 19F NMR (298 K,
CDCl3, 282.4 MHz; δ): -115.8 (2 o-F, 3J Pt,F ) 258.9 Hz), -165.2
(2 m-F), -165.7 (1 p-F) ppm. 31P NMR (298 K, CDCl3, 121.4
2
2
MHz; δ): 31.1 (d, P(3) or P(4), J P(1),P(3) or J P(2),P(4) ) 292 Hz,
1J Pt,P ) 2394 Hz), 21.3 (d, P(4) or P(3), J P(2),P(4) or J P(1),P(3)
297 Hz, J Pt,P ) 2175 Hz), from -95 to -118 (complex signals
due to P(1) and P(2) atoms) ppm.
)
2
2
1
[(C6F 5)(P P h 3)P t (µ-P P h 2)P t (P P h 3)(CO)] (6). CO was
bubbled through a solution of 3 (0.123 g, 0.080 mmol) in CH2-
Cl2 (6 mL) for 10 min. Hexane (10 mL) was added, and the
solution was evaporated to ca. 10 mL by bubbling CO. A yellow
solid 6 crystallized, which was filtered off and washed with 2
× 1 mL of hexane. Anal. Found (calcd) for C55F5H40OP3Pt2:
C, 50.8 (51.0); H, 3.25 (3.1). IR (Nujol): 945 cm-1; 776 cm-1
(X-sensitive, C6F5); 2039 cm-1 (ν(CtO)). 19F NMR (298 K,
CDCl3, 282.4 MHz; δ): -115.2 (2 o-F, 3J Pt,F ) 362.7 Hz), -165.7
(1 p-F + 2 m-F) ppm. 31P NMR (298 K, CDCl3, 121.4 MHz; δ):
1
136.5 (broad s, P(1), J Pt,P(1) ) 2721 and 2866 Hz), 27.2 (broad
3
1
2
d, P(2) or P(3), J P(2),P(3) ) 119 Hz, J Pt,P ) 3753 Hz, J Pt,P
)
3
1
262 Hz), 18.9 (broad d, P(3) or P(2), J P(2),P(3) ) 119 Hz, J Pt,P
) 3113 Hz, J Pt,P ) 363 Hz) ppm.
2
Cr yst a l St r u ct u r e An a lyses of [{(C6F 5)(P P h 3)P t (µ-
P P h 2)(µ-H)}2P t]‚C6H12‚3/8C6H14 (2‚C6H12‚3/8C6H14), [(C6F 5)-
(P P h 3)P t(µ-P P h 2)P t(P P h 3)2]‚1/2C7H8 (3‚1/2C7H8), an d [(C6F5)-
(P P h 3)P t(µ-P P h 2)2P t(H)(P P h 3)2] (5). Crystal data and other
details of the structure analysis are presented in Table 4.
Suitable crystals of 2, 3, and 5 were obtained by slow diffusion
of petroleum ether (2) or n-hexane (3 and 5) into a solution of
ca. 0.025 g of the complex in toluene (3) or in CH2Cl2 (2 and
5). Crystals were mounted at the end of a glass fiber. For 2,
(23) Sheldrick, G. M. SHELXL-93, a Program for Crystal Structure
Determination; University of Go¨ttingen, Go¨ttingen, Germany, 1993.
(24) Sheldrick, G. M. SHELXL-97, a Program for Crystal Structure
Determination; University of Go¨ttingen, Go¨ttingen, Germany, 1997.

Phosphido-Bridged Derivatives of Pt(I) and Pt(II)
Organometallics, Vol. 20, No. 5, 2001 859
unsuccessful. The presence of toluene in the crystals was
confirmed by spectroscopic analysis (1H NMR). To complete
the electron density in the structural model, three partial-
occupancy methyl carbon atoms were geometrically placed,
Ack n ow led gm en t. We thank the Direccio´n General
de Ensen˜anza Superior of Spain for financial support
(Project PB98-1595-C02-01). E.A. and A.M. acknowledge
the Diputacio´n General de Arago´n and DGES of Spain,
respectively, for their grants. We are most indebted to
Servei Central d’Instrumentacio´ Cient´ıfica (SCIC) of the
Universitat J aume I (Castello´, Spain) for providing us
with X-ray facilities.
bonded to the ring carbon atoms present in the asymmetric
1
unit with assigned
/ occupancies and constrained bond
6
distances. Finally, all the atoms of the toluene moiety were
refined with a common isotropic thermal parameter. One
molecule of acetone was refined with full occupancy. No
attempts to include in the model the hydrogen atoms of the
toluene were made. Full-matrix least-squares refinement of
these models against F2 converged to the final residual indices
given in Table 4. Final difference electron density maps showed
11 features above 1 e/Å3 (maximum/minimum 1.57/-1.05 e/Å3)
with the largest peaks lying closer than 1 Å to the platinum
or solvent atoms for 2, one feature above 1 e/Å3 (maximum/
minimum 1.07/-1.32 e/Å3) being close to one of the platinum
atoms for 3, and 11 features above 1 e/Å3 (maximum/minimum
1.57/-1.42 e/Å3) with the largest peaks lying closer than 1 Å
to the platinum atoms for 5.
Su p p or tin g In for m a tion Ava ila ble: Tables of all atomic
positional and equivalent isotropic displacement parameters,
anisotropic displacement parameters, all bond distances and
bond angles, hydrogen coordinates, and isotropic displacement
parameters for the crystal structures and fully labeled figures
of complexes 2, 3, and 5. This material is available free of
charge via the Internet at http://pubs.acs.org.
OM0007973