Synthesis of phosphido-bridged phosphinito platinum(I) complexes by reaction of cis-PtCl2(PHCy2)2 with oxygenated bases - Crystal structure of [(PCy2OMe)Pt(μ-PCy2)] 2(Pt-Pt)

Article abstract of DOI:10.1002/ejic.200500510

Reaction of cis-PtCl₂(PHCy₂)₂ (1) with oxygenated bases leads to phosphido-bridged dinuclear complexes. The product obtained using sodium hydroxide is the asymmetric Pt¹ complex [(Cy₂PH)Pt(μ-PCy₂)(κ²P,O-μ-Cy ₂PO)Pt(Cy₂PH)](Pt-Pt) (2), which represents a rare example of a complex containing a Pt-Pt-P-O cycle. The reaction products between 1 and NaOR (R = Me, Et) depend on experimental conditions: lack of base results in the formation of trans-[Pt(PHCy₂) Cl(μ-PCy₂)]₂ (3) as the main product. Using an excess of base at 50°C allowed the isolation of the symmetric Pt^I dimers [(PCy₂OR)P(μ- PCy₂)]₂(Pt-Pt) (5, R = Me; 7, R = Et) containing two alkyl dicyclohexylphosphinito ligands. The asymmetric compounds [(PCy ₂H)Pt(μ-PCy₂)₂Pt(PCy₂OR)](Pt-Pt) (4, R = Me; 8, R = Et) form after work-up of the reaction of 1 with excess NaOR (8 equiv.) in toluene/methanol at room temperature. Investigations on the mechanism of formation of phosphinito Pt^I complexes (carried out also employing NaOtBu and NaOPh as oxygenated bases) show that the first two steps of the overall reaction are the metathesis leading to cis-Pt(OR) ₂(PHCy₂)₂ and the subsequent formation of terminal phosphido complexes through ROH elimination. Single crystal X-ray diffraction showed that molecules of 5 are located on cristallographic inversion centres; hence their necessarily planar Pt₂P₂ core contains a Pt-Pt bond. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200500510

FULL PAPER
Synthesis of Phosphido-Bridged Phosphinito Platinum( ) Complexes by
I
Reaction of cis-PtCl2(PHCy2)2 with Oxygenated Bases – Crystal Structure of
[(PCy2OMe)Pt(µ-PCy2)]2(Pt–Pt)
Vito Gallo,[a] Mario Latronico,[a,d] Piero Mastrorilli,*[a] Cosimo F. Nobile,[a]
Gian P. Suranna,[a] Giuseppe Ciccarella,[b] and Ulli Englert[c]
Keywords: Platinum / Bridging ligands / Phosphinites / Oxygenated bases
Reaction of cis-PtCl2(PHCy2)2 (1) with oxygenated bases
leads to phosphido-bridged dinuclear complexes. The prod-
uct obtained using sodium hydroxide is the asymmetric PtI
complex [(Cy2PH)Pt(µ-PCy2)(κ2P,O-µ-Cy2PO)Pt(Cy2PH)](Pt–
Pt) (2), which represents a rare example of a complex con-
taining a Pt–Pt–P–O cycle. The reaction products between 1
and NaOR (R = Me, Et) depend on experimental conditions:
lack of base results in the formation of trans-[Pt(PHCy2)Cl(µ-
PCy2)]2 (3) as the main product. Using an excess of base at
50 °C allowed the isolation of the symmetric PtI dimers
[(PCy2OR)Pt(µ-PCy2)]2(Pt–Pt) (5, R = Me; 7, R = Et) containing
two alkyl dicyclohexylphosphinito ligands. The asymmetric
compounds [(PCy2H)Pt(µ-PCy2)2Pt(PCy2OR)](Pt–Pt) (4, R =
Me; 8, R = Et) form after work-up of the reaction of 1 with
excess NaOR (8 equiv.) in toluene/methanol at room tem-
perature. Investigations on the mechanism of formation of
phosphinito PtI complexes (carried out also employing Na-
OtBu and NaOPh as oxygenated bases) show that the first
two steps of the overall reaction are the metathesis leading
to cis-Pt(OR)2(PHCy2)2 and the subsequent formation of ter-
minal phosphido complexes through ROH elimination. Sin-
gle crystal X-ray diffraction showed that molecules of 5 are
located on crystallographic inversion centres; hence their
necessarily planar Pt2P2 core contains a Pt–Pt bond.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
can act either as nucleophiles and/or as bases, triggering
different reaction pathways depending on both the nature
of R and the experimental conditions.
Introduction
Secondary phosphanes are attractive as ligands for tran-
sition metals because they add some peculiar characteristics
to the typical σ basicity and π acidity of the trivalent phos-
phorus compounds because of the presence of the reactive
P–H bond: (i) the capability to form polynuclear complexes
in which the metal atoms are linked by phosphido bridges;
(ii) the possibility to give rise to a metal–hydrogen bond by
intramolecular oxidative addition.
Pursuing our studies on platinum complexes with bulky
secondary phosphanes such as di-tert-butylphosphane[1,2]
and dicyclohexylphosphane,[3] we recently became inter-
ested in the reactivity of cis-PtCl2(PHCy2)2 (1) with NaOR
(R = H, Me, Et, Ph, tBu). The latter compounds, in fact,
The reaction of alkaline alkoxides with phosphanyl PtII
complexes has been used for the preparation of alkoxo com-
plexes, starting from the corresponding chloro species.[4–8]
In some cases the alkoxo complexes are not stable and give
rise to redox processes leading to decomposition prod-
ucts,[9] to hydride complexes of platinum()[10] or to zero-
valent platinum compounds.[11] The reducing ability of al-
kaline alkoxides towards halide metal complexes has been
demonstrated also for Ni[12] and Pd[13] compounds.
Herein we describe the reactivity of cis-PtCl2(PHCy2)2
(1) with sodium hydroxide, alkoxides and phenoxide, which
led to phosphido-bridged binuclear platinum compounds,
the nature of which depended on both the base and the
reaction conditions (Scheme 1).
[a] Dipartimento di Ingegneria delle Acque e di Chimica del Po-
litecnico di Bari,
via Orabona 4, 70125 Bari, Italy
Fax: +39-080-5963611
E-mail: p.mastrorilli@poliba.it
Results and Discussion
[b] Dipartimento di Ingegneria dell’Innovazione, University of
Lecce,
Via Monteroni, 73100 Lecce, Italy
Contrary to trans-PtCl2(PHtBu2)2, whose reaction with
oxygenated bases such as NaOMe,[2] NaOEt[14] or NaOH[15]
was ineffective, the reaction of 1 with NaOH in a biphasic
CH2Cl2/H2O system proceeded smoothly to form a new di-
nuclear PtI complex whose spectroscopic features and ESI-
MS analysis indicate as [(Cy2PH)Pt(µ-PCy2)(κ2P,O-µ-
[c] Institut für Anorganische Chemie der RWTH,
Landoltweg 1, 52074 Aachen, Germany
[d] On leave of absence from Dipartimento di Ingegneria e Fisica
dell’Ambiente, Università della Basilicata,
viale dell’Ateneo Lucano 10, 85100 Potenza, Italy
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
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DOI: 10.1002/ejic.200500510
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V. Gallo et al.
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Scheme 1.
Cy2PO)Pt(Cy2PH)](Pt–Pt) (2). The 31P{1H} NMR spec-
The characterisation of 2 was completed by IR, elemen-
trum of 2 (Figure 1) showed 4 mutually coupled doublets tal and ESI-MS analysis. In particular, the IR spectrum
of doublets of doublets flanked by 195Pt satellites centred at showed two weak bands in the region of P–H stretching
δ = 134.4, δ = 94.6, δ = 18.5 and δ = 15.9 ppm.
(2279 and 2252 cm–1) and bands at 816 and 1024 cm–1 as-
Of these, the latter two can be ascribed to coordinated cribable to the P–O stretchings. Eventually, the ESI-MS
PCy2H (comparison with proton-coupled spectrum gave spectrum showed the signals corresponding to [M + H]+
1JP,H of 310 Hz and 323 Hz respectively) while that at δ = with an isotope pattern identical to that calculated on the
94.6 is ascribable to a deshielded P–O ligand. The remain- basis of the natural abundances (Figure 3).
ing low field signal at δ = 134.4 is flanked by three different
Complex 2 is a rare example of an asymmetric monopho-
sets of satellites and can be attributed to a phosphide in- sphido-bridged PtI complex. The spectroscopic data sum-
volved in a three-membered Pt2P ring[16,17] bridging two in- marised above are consistent either with structure A, in
1
equivalent Pt atoms. The H NMR spectrum showed, be- which the P(O)Cy2 ligand acts as monodentate (κ-P bound
side cyclohexyl protons, two signals attributable to the hy- to Pt2), or with structure B, in which the P(O)Cy2 acts as
drogens directly bound to P in coordinated PCy2H, which bidentate (κ2-P,O) bridging the two Pt atoms (Figure 4).
were attributed to the proper PCy2H ligand on the basis of
An equilibrium between the two structures might also be
1H–31P HMQC experiments (Supporting Information, conceived. NMR features can help in discriminating be-
ESI 1). The 195Pt{1H} NMR spectrum consisted of two tween the two structures. We have previously noticed that
dddd centred at δ = –4798 (Pt1) and δ = –5205 (Pt2) (Fig- binuclear monobridged dicyclohexylphosphane complexes
ure 2).
of Pd and Pt such as [(Cy2PH)(Cl)Pt(µ-PCy2)Pt(Cy2PH)2]-
Figure 1. 31P{1H} NMR spectrum of 2 (161 MHz, 295 K, C6D6).
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Phosphido-Bridged Phosphinito Platinum()
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Figure 2. 195Pt{1H} NMR spectrum of 2 (295 K, C6D6). a: Pt1; b: Pt2.
spectrum recorded at 195 K did not differ significantly from
those found at 295 K.
The reaction of 1 with solid sodium methoxide (2 equiv.)
in toluene at room temperature gave the symmetric dimer
trans-[Pt(PHCy2)Cl(µ-PCy2)]2 (3) as the main product (82%
yield).[20] Complex 3 was characterised by multinuclear
NMR, IR, ESI-MS and elemental analysis. The appearance
of an AAЈXXЈ spin system in the 31P{1H} NMR spectrum
for the isotopomer not containing 195Pt substantiates the
trans geometry of the complex. Computer simulation of the
spectrum, using as starting chemical shifts and coupling
constants those extractable directly from the experimental
spectrum,[21] gave the spectroscopic features reported in
Table 1 (Supporting Information, ESI 3–4). The values
3
3
2
3
,Pt1
found for JPAЈ
,PXЈ
core.[22]
= JPA,Pt2, for JPX,PXЈ and for JPA,PX =
3JPAЈ
are consistent with a planar geometry of the Pt2P2
Figure 3. ESI-MS spectrum of 2 (bottom trace: calculated).
Table 1. Spectroscopic features for 3 (CDCl3, 295 K).
Figure 4. Possible structures of 2.
(Pt–Pt)[3]
or
[(Cy2PH)(Cl)Pd(µ-PCy2)Pd(Cy2PH)2]-
PA
15.1
4.2
357.3
9.2
PAЈ
PX
PXЈ
Pt1
Pt2
79
1948
2399
2048
(Pd–Pd)[18] (Supporting Information, ESI 2) are character-
ised by broad 31P{1H} NMR signals for all ligands except
the bridging PCy2, a feature that was ascribed to hindered
rotation of the PHCy2 ligands about the metal–P bond. The
sharp signals found in the 31P{1H} NMR of 2 (Figure 1)
favour structure B, in which both PHCy2 (in particular that
bound to Pt2) have more room to freely rotate around the
Pt–P bonds.
PA
4.2
357.3
9.2
–137.9
–150.8
2048
9.2
1948
79
2048
2399
PAЈ
PX
PXЈ
Pt1
Pt2
15.1
9.2
357.3
79
357.3
–150.8
–137.9
2399 –4014
2048
1948
79
1948
2399
–4014
The analogous palladium() complex trans-[Pd(PHCy2)-
The presence of a Pt–P–O–Pt ring in 2 is corroborated Cl(µ-PCy2)]2 is the reaction product between cis-
by the literature. In fact, XRD analysis of the related PtI PdCl2(PHCy2)2 and 1 equiv. NaOPh and reacts at 50 °C
complex [Pt(κ2P,O-µ-OPPh2)(PMePh2)]2 showed that each with 1 more equiv. NaOPh to afford the bis(dicyclohexyl)-
platinum atom is involved in a four-membered Pt–P–O–Pt phenylphosphinito palladium() complex [(PhOPCy2)Pd(µ-
ring.[19]
PCy2)]2.[23] This reaction is not transferable to our system
Finally, equilibrium between structures A and B seems because 3 was recovered unaltered after 24 h stirring with
unlikely because the signals found in the 195Pt{1H} NMR 2 equiv. NaOMe in toluene at 50 °C (Scheme 2). A possible
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V. Gallo et al.
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explanation for the different reactivity of trans-[Pd- mutually coupled [1JPt,Pt = 337 Hz)] and were centred at δ
(PHCy2)Cl(µ-PCy2)]2 and 3 might reside in a different = –5530 and δ = –5570 respectively.
strength of the metal–Cl bond. IR stretching of the Pd–Cl
bond (275 cm–1) is in fact 14 cm–1 red-shifted with respect spectrum the signal of the bridging phosphide at δ = 245.3
The symmetric dimer 5 showed in the 31P{1H} NMR
to that of the Pt–Cl in 3 (289 cm–1).
and that of the terminal methyl dicyclohexylphosphinite at
The reaction of 1 with excess NaOMe (5 equiv.) in tolu- δ = 171.2. The 195Pt{1H} NMR spectrum consisted of a
ene/methanol at room temperature for 1 day afforded, after doublet of triplets centred at δ = –5570 ppm.
work-up, a mixture of products made up of the asymmetric
Prolonging to 7 days the stirring time of the reaction
PtI complex [(PCy2H)Pt(µ-PCy2)2Pt(PCy2OMe)](Pt–Pt) (4, between 1 and excess NaOMe described above resulted in
60%), the symmetric PtI dimer [(PCy2OMe)Pt(µ-PCy2)]2- the synthesis of the dimer 5 as the main product, devoid of
(Pt–Pt) (5, 35%) and traces of 3 (Scheme 3).
the asymmetric complex 4. This result prompted us to mon-
Complex 4 showed in the 31P{1H} NMR spectrum two itor the reaction by 31P{1H} NMR in order to ascertain
low field signals and one signal in the region of coordinated whether 4 is the precursor of 5, so as to shed some light on
PHCy2 (each flanked by 195Pt satellites due to isotopomers the reaction mechanism. The spectrum recorded after
containing one or two NMR active Pt atoms). The low field 30 min reaction showed the transformation of 1 into cis-
signals are a doublet of doublets centred at δ = 245.7 and Pt(PHCy2)2(OMe)2 (6) and traces of 3. Prolonging the reac-
a doublet of triplets centred at δ = 173.6. Both signals are tion time resulted in the progressive decrease of signals due
due to phosphorus atoms not directly bound to hydrogens to 6 with contemporary appearance of signals due to 5,
(comparison with proton coupled spectra) and are easily which became predominant after 2 days.
assigned, the first to a dicyclohexylphosphido group in-
Complex 6 gave a singlet with 195Pt satellites in the
1
volved in three-membered rings, and the second, according 31P{1H} NMR spectrum [δ = 7.2, JP,Pt = 3267 Hz], which
to 1H NMR and ESI-MS data, to a coordinated PCy2OMe. split into a doublet in the proton-coupled spectrum [1JP,H
The remaining signal is a doublet of triplets (further split = 341 Hz)]. The corresponding 195Pt{1H} NMR spectrum
1
in the proton-coupled spectrum due to the 318 Hz JP,H
)
consisted in a triplet centred at δ = –4233 [1JP,Pt = 3267 Hz].
centred at δ = 19.1 ascribed to a coordinated PHCy2. The Experiments carried out in deuterated solvent allowed as-
1H NMR spectrum showed, beside resonances due to cyclo- signation of the 1H NMR resonance of the coordinated
3
1
4
hexyl protons, a doublet at δ = 3.94 [3 H, JP,H = 13 Hz] Cy2PH [δ = 3.6, JH,P = 341 Hz] and OCH3 [δ = 3.5, JH,P
ascribable to the methyl group of the coordinated PCy2- = 3.9 Hz; 3JH,Pt = 25 Hz]. Complex 6, which is very soluble
OMe and a doublet of multiplets due to the hydrogen di- in the reaction mixture so as to prevent its precipitation at
rectly bound to the phosphorus of the coordinated PCy2H low temperature, could not be isolated in a pure state be-
[δ = 6.36, 1JP,H = 318 Hz]. The two 195Pt{1H} NMR signals cause of its fast and irreversible transformation into 4 dur-
of the atoms directly bound to PHCy2 and PCy2OMe were ing solvent removal either by reduced pressure or by bub-
Scheme 2.
Scheme 3.
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Phosphido-Bridged Phosphinito Platinum()
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bling of inert gas. This explains our experimental results: Table 2. Selected bond lengths [Å] and angles [°] for 5.
the starting complex 1 reacts with excess methoxide to give
Pt(1)–P(2)
Pt(1)–P(1)Ј
Pt(1)–P(1)
Pt(1)–Pt(1)Ј
P(2)–O(1)
C(1)–O(1)
P(1)–Pt(1)–P(2)
P(1)Ј–Pt(1)–P(2)
Pt(1)Ј–Pt(1)–P(1)
Pt(1)Ј–Pt(1)–P(1)Ј
Pt(1)Ј–Pt(1)–P(2)
2.2150(14)
2.2982(15)
2.3058(14)
2.6307(5)
1.626(4)
6 (and traces of 3, which does not further react), which
slowly transforms into 5. If the reaction is stopped when 6
is still present (e.g. 1 day), work-up of the crude results in
the formation of a mixture containing 4 (formed mainly
during solvent removal) and 5. Complex 4 could be ob-
tained in a pure state after work-up of the reaction of 1
with excess NaOMe (8 equiv.) in toluene/methanol at room
temperature, and 5 could be obtained in 67% yield after
6 h by reacting 1 with excess NaOMe (8 equiv.) in toluene/
methanol at 50 °C. Longer reaction times resulted in lower
isolated yields because of decomposition of 5 into unidenti-
fied products.
Slow evaporation of a toluene solution of 5 deposited
yellow-orange crystals suitable for single-crystal X-ray dif-
fraction. The structure of a molecule in the crystal is shown
in Figure 5. Significant bond lengths and angles are given
in Table 2. The complex crystallises in the monoclinic space
group P21/c. The molecule contains an inversion centre, and
therefore the Pt2P2 quadrilater with angles of 110.30(4)°
and 69.70(4)° is planar for reasons of symmetry; the OCH3
oxygen atoms also lie in this plane within experimental er-
ror. The presence of a Pt–Pt bond is evidenced by an in-
termetal distance of 2.6307(5) Å, which is comparable with
the 2.6127(6) Å and 2.604(1) Å Pt–Pt distances of
[(PtBu2H)Pt(µ-PtBu2)2Pt(CO)](Pt–Pt)[24] and [(PPh3)Pt(µ-
PPh2)2Pt(PPh3)](Pt–Pt)[25] respectively. The average Pt–Pt
bond length for 66 error-free observations in the CSD[26]
amounts to 2.633 Å.
1.365(7)
127.53(5)
122.17(5)
55.01(4)
55.29(4)
177.45(4)
Pt(µ-PCy2)]2(Pt–Pt) (7) in 55% yield after only 2 h. How-
ever, because of the higher reactivity shown by EtONa, in
this case it was not possible to isolate the asymmetric com-
plex [(PCy2H)Pt(µ-PCy2)2Pt(PCy2OEt)](Pt–Pt) (8) in a
pure state. It was observed in mixture with 7 and character-
ised in solution by multinuclear NMR spectroscopy.
The experimental data presented so far allow some
mechanistic considerations to be put forward.
A possible explanation for the selectivity towards 3 of
the reaction between 1 and NaOMe (2 equiv.) in toluene
could be the accumulation, in these conditions, of the mon-
osubstituted methoxo complex cis-PtCl(OMe)(PHCy2)2,
which can dimerise to 3 by loss of methanol (Scheme 4).
Such accumulation could derive from the constant lack of
methoxide present in the reaction medium, because of its
scarce solubility in toluene. Complex cis-PtCl(O-
Me)(PHCy2)2 could be detected by recording 31P{1H}
NMR spectra of CD2Cl2 solutions of 1, to which an equi-
molar amount of NaOMe was added. The solution showed,
along with the singlets of residual 1 and 6, two mutually
coupled [2JP,P = 15 Hz] doublets centred at δ = 17.3 [1JP,Pt
= 3814 Hz] and δ = 8.7 [1JP,Pt = 2942 Hz] attributable to
the P trans to Cl and P trans to OMe respectively. Analo-
gous results were obtained by using NaOEt instead of Na-
OMe as limiting reagent. In this case the spectroscopic fea-
tures of cis-PtCl(OEt)(PHCy2)2 are δ = 16.6 [1JP,Pt
=
3734 Hz, P trans to Cl] and δ = 7.4 [1JP,Pt = 2966 Hz, P
trans to OEt] [2JP,P = 18 Hz].
Figure 5. Displacement ellipsoid plot of 5;[27] ellipsoids are scaled
to 30% probability, H atoms have been omitted for clarity.
The Pt–Pµ distances (2.30 Å) are longer than Pt–Pt
[2.2150(14) Å]. The external angle P(1)Ј–Pt(1)–P(2)
[122.17(5)°] is smaller than P(1)–Pt(1)–P(2) [127.53(5)°] be-
cause of a rather short (2.01 Å) and repulsive H···H contact
between a methoxy hydrogen and a H atom of a cyclohexyl
substituent bonded to P(1).
The reactivity shown by 1 towards NaOEt parallels that
found for NaOMe: the reaction of 1 with 8 equiv. EtONa
at 50 °C in a toluene/ethanol mixture afforded [(PCy2OEt)- Scheme 4. Proposed mechanism for the formation of 3.
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As to the formation of the alkylphosphinito PtI dimers coordinated to ruthenium;[31] (v) MeOP(Ph)R (R = H, Ph,
observed when the reaction was carried out in the presence OMe) from PPhR– coordinated to osmium and methox-
of excess NaOR (R = H, Me, Et), a possible mechanism is ide.[32] In all cases the formation of the P–O bond is ex-
depicted in Scheme 5.
plained in terms of intramolecular [intermolecular in case v]
The initially formed metathesis product cis-Pt(PHCy2)2- attack of RO– on a coordinated phosphide (or phosphane),
(OR)2 can formally lose ROH, giving the terminal phos- substantially identical to our proposal for the transforma-
phido species a. The latter can give rise to an intramolecular tion of a into b.
process involving the metal, the coordinated RO group and
Path 2 of Scheme 5 could also explain the formation of
the coordinated terminal phosphide, resulting in the phos- the asymmetric complexes [(PCy2H)Pt(µ-PCy2)2Pt-
phinito intermediates b. When R is an alkyl group, intra- (PCy2OR)](Pt–Pt), which could be derived from intermedi-
molecular oxidative addition of the P–H bond to Pt fol- ate c (R = Me, Et) after loss of alcohol and ring closure.
lowed by hydrogen elimination and dimerisation (path 1) The circumstance that the asymmetric compounds formed
would account for the observed formation of the symmetric only when reaction mixtures containing significant amounts
dimers [(PCy2OR)Pt(µ-PCy2)]2(Pt–Pt). The sequence of re- of complexes cis-Pt(PHCy2)2(OR)2 were evaporated can be
actions leading from b to [(PCy2OR)Pt(µ-PCy2)]2(Pt–Pt) explained by the fact that, under reaction conditions, the
has already been proposed for the synthesis of several anal- transformation from a to b is fast, so that a never accumu-
ogous systems.[3,18,28]
lates in the reaction medium. Putting mixtures containing
When R is H, the intramolecular oxidative addition of cis-Pt(PHCy2)2(OR)2 under vacuum would progressively
the P–H bond to Pt is disfavoured by the co-presence in the enhance the amount of a in solution, rendering the forma-
hypothetically formed Pt(PCy2)(H)(PCy2OH) of a strongly tion of c competitive with Path 1.
basic centre (the terminal phosphide) and an acidic proton
The transformation of cis-Pt(PHCy2)2(OR)2 into a when
(Cy2POH). Reaction of a with b (R = H, path 2) can give R is Me or Et deserves comment. It is known that mononu-
intermediate c, which evolves into the final product 2 after clear dimethoxo PtII complexes are unstable and give alde-
loss of water and ring closure.
hyde, alcohol and traces of CO.[9] In our case, intermediate
The central point of the suggested mechanism is the me- a could form either by alcohol elimination or a dehydro-
tal assisted formation of the P–O bond that leads to the genative pathway consisting in the formation of Pt hydride
dicyclohexylphosphinito ligands. In the literature, few ex- with loss of aldehyde and subsequent loss of H2 (Scheme 6).
amples can be found of such a transformation. In particu-
In order to ascertain which of the above-mentioned path-
lar, the following have been reported: (i) PhOPCy2 from ways is operative in our system, we have carried out reac-
PHCy2 and phenoxide ion coordinated to palladium;[23] tions between 1 and phenoxide or tert-butoxide, two bases
(ii) MeOPPh2 from PPh2Im (Im = 1-methylimidazole) and incapable of forming the aldehyde contemplated by path ii.
methoxide coordinated to ruthenium;[29] (iii) 1-phenyl-3H-
The reaction of 1 with NaOPh (8 equiv.) in toluene at
2,1-benzoxaphosphole from o-(diphenylphosphanyl)benzyl 50 °C for 1 day afforded the symmetrical PtI dimer [(PCy2-
alkoxide coordinated to platinum;[30] (iv) (4-methylphenyl)- OPh)Pt(µ-PCy2)]2(Pt–Pt) (9), whereas the asymmetric PtI
dimethylphosphinite from PMe3 and 4-methylphenoxide complex [(PCy2H)Pt(µ-PCy2)2Pt(PCy2OtBu)](Pt–Pt) (10)
Scheme 5. Proposed mechanism for reactions carried out with excess NaOR.
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Phosphido-Bridged Phosphinito Platinum()
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spectrometer. THF (CH2Cl2 in the case of 3) solutions of the com-
plexes were infused with a Cole-Parmer syringe pump. All the ESI-
MS spectra were recorded with an Agilent LC/MS SL series instru-
ment adopting the following general conditions: electrospray, posi-
tive ions, flow rate 0.200 mLmin–1, drying gas flow 4.0 lmin–1,
nebuliser pressure 25 psi, drying gas temperature 300 °C, capillary
voltage 4000 V, mass range 400–1400 m/z. The isotopic pattern was
calculated by the Isotope Pattern Viewer software, downloadable
free of charge from the www.surfacespectra.com website. NMR
spectra were recorded with a BRUKER Avance 400 spectrometer;
frequencies are referenced to Me4Si (1H and 13C), 85% H3PO4 (31P)
and H2PtCl6 (
195Pt). NMR simulation was performed using the
program WINDAISY.
[(Cy2PH)Pt(µ-PCy2)(κ2P,O-µ-Cy2PO)Pt(Cy2PH)](Pt–Pt) (2): An
aqueous solution of NaOH (0.7 mL, 0.90 ⁾ was added to a vigor-
ously stirred colourless CH2Cl2 solution (10 mL) of cis-[Pt(PHCy2)2-
Cl2] (0.203 g, 0.306 mmol) at room temperature. After 3 days the
yellow organic phase was separated, washed twice with water and
dried on Na2SO4. After filtration the solvent was evaporated to
dryness under reduced pressure, affording 152 mg of pure 2 as a
yellow powder (83%). The complex was air sensitive in solution,
very soluble in dichloromethane, toluene and n-hexane and scarcely
soluble in acetone. C48H90OP4Pt2 (1197.28): calcd. C 48.15, H 7.58;
Scheme 6.
was the main product of the reaction of 1 with NaOtBu
(8 equiv.) in toluene at 50 °C.
Although the dehydrogenative pathway ii of Scheme 6
cannot be conclusively ruled out when NaOMe or NaOEt
were the bases, these findings indicate that the loss of
alcohol (path i) can be responsible (as in the cases of Na-
OPh or NaOtBu) for the transformation of cis-Pt(PHCy2)2-
(OR)2 into the intermediate Pt(PHCy2)(PCy2)(OR) (a).
The diverse behaviour observed passing from NaOPh to
NaOtBu can be explained on the basis of the high differ-
ence in basicity exhibited by the two oxygenated bases and
further supports the mechanism proposed. In fact, accord-
ing to Scheme 5, the formation of asymmetric monophos-
phinito dimers is related to the contemporary presence in
solution of significant amounts of intermediates a and b. In
the case of NaOPh the formation of a is disfavoured be-
cause of the low basicity of phenoxide[33] and it is presum-
able that as soon as it forms it gives b, which evolves into
9. On the contrary, with the very strong base NaOtBu, the
loss of tBuOH leading to a is very fast, so that path 2 of
Scheme 5 becomes predominant.
In conclusion, the presence of the relatively weak P–H
bonds determines a rich reactivity of 1 with oxygenated
bases. Depending on the base and on the experimental con-
ditions it is possible to address the reaction towards the
phosphido-bridged PtII complex 3, the asymmetric alkyl di-
cyclohexylphosphinito complexes 4, 8, 10 or the bis dicyclo-
hexylphosphinito complexes 5, 7, 9. Using NaOH resulted
in the smooth formation of a PtI complex, showing a rare
example of a Pt–P–O–Pt ring.
found
C48H90OP4Pt2: 1196.52 amu; found: 1197.5 [M + H]+. M.p. 135 °C
(dec.). IR (KBr): ν = 2279 (w, P–H), 2252 (w, P–H), 1024 (s,
C 48.25, H 7.60. LC-MS: exact mass calcd. for
˜
max
P=O) cm–1. 1H NMR (400 MHz, C6D6, 295 K): δ = 5.68 [m,
2
1
1JH(2),P(4) = 310, JH(2),Pt(2) = 53 Hz, H(2)], 4.85 [m, JH(1),P(2)
=
323, JH(1),Pt(1) = 112 Hz, H(1)] ppm. 31P{1H} NMR (161 MHz,
C6D6, 295 K): δ = 134.4 [sharp ddd, 2JP(1),P(2) = 48, 2JP(1),P(3) = 229,
2
2JP(1),P(4) = 54, JP(1),Pt(1) = 4091, JP(1),Pt(2) = 2985 Hz, P(1)], 94.6
1
1
[sharp ddd, 2JP(3),P(1) = 229, 3JP(3),P(2) = 29, 2JP(3),P(4) = 5, 1JP(3),Pt(2)
2
2
= 3061, JP(3),Pt(1) = 42 Hz, P(3)], 18.5 [broad ddd, JP(4),P(1) = 54,
3JP(4),P(2) = 112, 2JP(4),P(3) = 5, 1JP(4),Pt(2) = 3682, 2JP(4),Pt(1) = 83 Hz,
2
3
3
P(4)], 15.9 [broad ddd, JP(2),P(1) = 48, JP(2),P(3) = 29, JP(2),P(4)
=
112, JP(2),Pt(1) = 4230, JP(2),Pt(2) = 107 Hz, P(2)] ppm. 195Pt{1H}
1
2
NMR (86 MHz, C6D6, 295 K): δ = –4798 [dddd, 1JPt(1),P(1) = 4091,
2
2
1JPt(1),P(2) = 4230, JPt(1),P(3) = 42, JPt(1),P(4) = 83 Hz, Pt(1)], –5205
1
2
1
[dddd, JPt(2),P(1) = 2985, JPt(2),P(2) = 107, JPt(2),P(3) = 3061,
1JPt(2),P(4) = 3682 Hz, Pt(2)] ppm.
trans-Dichlorodi-µ-cyclohexylphosphidobis(dicyclohexylphosphane)-
platinum(II) (3): A suspension of cis-[Pt(PHCy2)2Cl2] (0.564 g,
0.85 mmol), CH3ONa (0.092 g, 1.70 mmol) in toluene (20 mL) was
vigorously stirred at room temperature (21 °C) for 3 days. The re-
sulting pale yellow suspension was evaporated under reduced pres-
sure. The residue was washed twice with n-hexane and the product
was extracted with 10 mL CH2Cl2. Evaporation of the solvent af-
forded trans-[Pt(PHCy2)(PCy2)Cl]2 as a white powder (0.439 g,
82%). The complex was air stable, very soluble in dichloromethane
and chloroform, scarcely soluble in toluene and insoluble in n-hex-
ane. C48H90Cl2P4Pt2 (1252.18): calcd. C 46.04, H 7.24, Cl 5.66;
found C 46.15, H 7.25, Cl 5.68. LC-MS: exact mass calcd. for
C48H90Cl2P4Pt2: 1250.5 amu; found: 1251.5 [M + H]+. M.p.
Experimental Section
General Remarks: All manipulations were carried out under pure
dinitrogen, using freshly distilled, thoroughly dehydrated and oxy-
gen-free solvents. All aromatic deuterated solvents were carefully
dehydrated (molecular sieves) and deoxygenated (freeze and
pump). cis-Dichlorobis(dicyclohexylphosphane)platinum() (1)
was prepared as described in ref.[3]
.
C, H elemental analyses were carried out on a Eurovector CHNS-
O Elemental Analyser. Cl elemental analysis was performed by
potentiometric titration using a Metrohm DMS Titrino. Melting
points were measured with a Gallenkamp apparatus and are uncor-
rected. Infrared spectra were recorded with a Bruker Vector 22
Ͼ300 °C. IR (nujol mull): ν
= 2337 (m, P–H), 289 (m, Pt–Cl)
˜
max
cm–1. 1H NMR (400 MHz, CDCl3, 295 K): δ = 3.9 (m, 1JH,P = 322,
Eur. J. Inorg. Chem. 2005, 4607–4616
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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V. Gallo et al.
2JH,Pt = 72 Hz, PH) ppm. 31P{1H} NMR and 195Pt{1H} NMR {[Cy2(EtO)P]Pt(µ-PCy2)}2(Pt–Pt) (7): A solution of EtONa in dry
FULL PAPER
spectroscopic data are reported in Table 1.
ethanol (1.0 , 2.5 mL) was added to a vigorously stirred suspen-
sion of cis-[Pt(PHCy2)2Cl2] (0.206 g, 0.311 mmol) in toluene
(10 mL) at 50 °C. After 2 h the resulting orange suspension was
evaporated under reduced pressure. The product was extracted with
3×5 mL hexane and precipitated, as a yellow powder, with acetone
(hot/cold). Isolated yield: 0.109 g, 55%. The complex was air sensi-
tive in solution, very soluble in dichloromethane, chloroform, hex-
ane and toluene, scarcely soluble in acetone and methanol.
C52H98O2P4Pt2 (1269.38): calcd. C 49.20, H 7.78; found C 49.12,
H 7.75. LC-MS: exact mass calcd. for C52H98O2P4Pt2: 1268.58
{(Cy2PH)Pt(µ-PCy2)2Pt[Cy2(MeO)P]}(Pt–Pt) (4): A solution of
CH3ONa in methanol (1.0 , 3.2 mL) was added to a vigorously
stirred suspension of cis-[Pt(PHCy2)2Cl2] (0.262 g, 0.395 mmol) in
toluene (10 mL) at room temperature. After 2 h the resulting
orange suspension was evaporated under reduced pressure. The
product was extracted with 3×5 mL hexane and precipitated, as a
yellow powder, with acetone (hot/cold). Isolated yield: 0.129 g,
54%. The complex was air sensitive in solution, very soluble in
dichloromethane, chloroform, hexane and toluene, scarcely soluble
in acetone and methanol. C49H92OP4Pt2 (1211.31): calcd. C 48.59,
H 7.66; found C 48.45, H 7.56. LC-MS: exact mass calcd. for
C49H92OP4Pt2: 1210.54 amu; found: 1211.5 [M + H]+. M.p. 150 °C
amu; found: 1269.6 [M + H]+. IR (nujol mull): νmax = 1263 (m, C–
˜
O), 1177 (w), 1102 (m), 1059 (m, P–O), 1001 (m), 849 (m), 818 (w),
749 (m), 525 (m), 462 (m) cm–1. 1H NMR (400 MHz, C6D6, 295 K):
3
δ = 4.39 (m, JH,H = 7.1 Hz, CH3CH2O) ppm. 31P{1H} NMR
(dec.). IR (KBr): ν
= 2234 (w, P–H), 1095 (s), 1020 (s, P–O),
˜
max
2
1
809 (s, P–O) cm–1. 1H NMR (400 MHz, C6D6, 295 K): δ = 6.36
(161 MHz, C6D6, 295 K): δ = 244.0 [t, JP(1),P(2) = 68, JP(1),Pt(1)
=
=
2
3
1
1
3
2481 Hz, P(1)], 167.3 [t, JP(2),P(1) = 68, JP(2),P(3) = 77, JP(2),Pt(1)
[m, JH,P = 318 Hz, H(1)], 3.94 (d, JH,P = 13 Hz, POCH3) ppm.
5451, JP(2),Pt(2) = 132 Hz, P(2)] ppm. 195Pt{1H} NMR (86 MHz,
2
31P{1H} NMR (161 MHz, C6D6, 295 K): δ = 245.7 [dd, JP(1),P(3)
2
1
1
2
1
1
C6D6, 295 K): δ = –5567 [dtd, JPt(1),P(1) = 2481 Hz, JPt(1),P(2)
=
= 67, JP(1),P(2) = 55, JP(1),Pt(1) = 2625, JP(1),Pt(2) = 2450 Hz, P(1)],
2
173.6 [dt, 3JP(3),P(2) = 76, 2JP(3),P(1) = 67, 1JP(3),Pt(2) = 5477 Hz, P(3)],
5451, JPt(1),P(3) = 132 Hz, Pt(1)] ppm.
19.1 [dt, 3JP(2),P(3) = 76, JP(2),P(1) = 55, JP(2),Pt(1) = 4800, JP(2),Pt(2)
2
1
2
= 47 Hz, P(2)] ppm. 195Pt{1H} NMR (86 MHz, C6D6, 295 K): δ
1
1
1
= –5530 [dt, JPt(1),P(1) = 2625, JPt(1),P(2) = 4800, JPt(1),Pt(2)
=
1
2
337 Hz, Pt(1)], –5570 [dtd, JPt(2),P(1) = 2450, JPt(2),P(2) = 47,
1
1JPt(2),P(3) = 5477, JPt(2),Pt(1) = 337 Hz, Pt(2)] ppm.
NMR Spectroscopic Features for 8: 1H NMR (400 MHz, C6D6,
1
295 K): δ = 6.23 [dm, JH(1),P(2) = 318 Hz, P(1)], 4.40 (pseudoquin-
3
3
3
tet, JH,P = 7, JH,H = 7 Hz, POCH2CH3), 1.56 (t, JH,H = 7 Hz,
POCH2CH3) ppm. 31P{1H} NMR (161 MHz, C6D6, 295 K): δ =
2
2
1
245.4 [dd, JP(1),P(3) = 64, JP(1),P(2) = 54, JP(1),Pt(1) = 2710,
1JP(1),Pt(2) = 2461 Hz, P(1)], 169.5 [dt, JP(3),P(2) = 77, JP(3),P(1)
=
=
3
2
1
3
2
{[Cy2(MeO)P]Pt(µ-PCy2)}2(Pt–Pt) (5): A solution of CH3ONa in
methanol (1.0 , 2.9 mL) was added to a vigorously stirred suspen-
sion of cis-[Pt(PHCy2)2Cl2] (0.240 g, 0.362 mmol) in toluene
(10 mL) at 50 °C. After 6 h the resulting orange suspension was
evaporated under reduced pressure. The product was extracted with
3×5 mL hexane and precipitated, as a yellow powder, with acetone
(hot/cold). Isolated yield: 0.150 g, 67%. The complex was air sensi-
tive in solution, very soluble in dichloromethane, chloroform, hex-
ane and toluene, scarcely soluble in acetone and methanol.
C50H94O2P4Pt2 (1241.33): calcd. C 48.38, H 7.63; found C 48.48,
H 7.65. LC-MS: exact mass calcd. for C50H94O2P4Pt2: 1240.55
amu; found: 1241.5 [M + H]+. M.p. 188 °C (dec.). IR (nujol mull):
64, JP(3),Pt(2) = 5458 Hz, P(3)], 19.5 [dt, JP(2),P(3) = 77, JP(2),P(1)
1
2
54, JP(2),Pt(1) = 4894, JP(2),Pt(2) = 54 Hz, P(2)] ppm. 195Pt{1H}
1
NMR (86 MHz, C6D6, 295 K): δ = –5524 [dt, JPt(1),P(1) = 2710,
1JPt(1),P(2) = 4894, 1JPt(1),Pt(2) = 333 Hz, Pt(1)], –5567 [dtd, 1JPt(2),P(1)
2
1
1
= 2461, JPt(2),P(2) = 54, JPt(2),P(3) = 5458, JPt(2),Pt(1) = 337 Hz,
Pt(2)] ppm.
ν
= 1259 (m, C–O), 1175 (w), 1103 (m), 1054 (m, P–O) cm–1.
˜
max
1H NMR (400 MHz, C6D6, 295 K): δ = 3.92 (d, JH,P = 13 Hz,
3
CH3O). 31P{1H} NMR (161 MHz, C6D6, 295 K): δ = 245.3 [dd,
2JP(1),P(2) = 68, JP(1),Pt(1) = 2475 Hz, P(1)], 171.2 [dd, JP(2),P(1)
=
1
2
68, 3JP(2),P(3) = 81, 1JP(2),Pt(1) = 5468, 2JP(2),Pt(2) = 126 Hz, P(2)] ppm.
{[Cy2(PhO)P]Pt(µ-PCy2)}2(Pt–Pt) (9): Sodium phenoxide (0.285 g,
2.46 mmol) was added to a stirred suspension of cis-[Pt(PHCy2)2-
Cl2] (0.204 g, 0.308 mmol) in toluene (5 mL). After 24 h stirring at
50 °C the suspension was filtered and the filtrate was concentrated
to 3 mL under reduced pressure. The product was obtained, as a
yellow solid, by precipitation with acetone (50 mg, 24%). The com-
plex was air sensitive in solution, very soluble in dichloromethane,
chloroform, hexane and toluene, scarcely soluble in acetone and
methanol. C60H98O2P4Pt2 (1365.47): calcd. C 52.78, H 7.23; found
C 52.59, H 7.20. LC-MS: exact mass calcd. for C60H98O2P4Pt2:
195Pt{1H} NMR (86 MHz, C6D6, 295 K): δ = –5570 [dtd, 1JPt(1),P(1)
1
2
= 2475, JPt(1),P(2) = 5468, JPt(1),P(3) = 64 Hz, Pt(1)] ppm.
1364.58 amu; found: 1365.6 [M + H]+. IR (KBr): νmax = 2925 (m),
˜
2848 (m), 1262 (s), 1229 (m), 1100 (vs, P–O), 1021 (vs, P–O), 873
4614
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 4607–4616

Phosphido-Bridged Phosphinito Platinum()
(m), 801 (vs), 678 (w), 518 (w), 501 (w) cm–1. 1H NMR (400 MHz, 2JH,Pt = 91 Hz, PH trans OPh) ppm. 31P{1H} NMR (161 MHz,
FULL PAPER
1
2
CD2Cl2, 295 K): δ = 7.25–7.02 (10 H, Ph), 2.4–0.7 (88 H, Cy) ppm.
CDCl3, 295 K): δ = 8.7 (d, JP,Pt = 3174, JP,P = 14 Hz, P trans
31P{1H} NMR (161 MHz, C6D6, 295 K) (Supporting Information, OPh), 15.2 (d, JP,Pt = 3653, JP,P = 14 Hz, P trans Cl) ppm.
1
2
2
1
1
ESI 5): δ = 242.7 [t, JP(1),P(2) = 71, JP(1),Pt(1) = 2469 Hz, P(1)],
195Pt{1H} NMR (86 MHz, CDCl3, 295 K): δ = –4323 (dd, JP,Pt
=
2
3
1
2
1
163.6 [t, JP(2),P(1) = 71, JP(2),P(3) = 82, JP(2),Pt(1) = 5489, JP(2),Pt(2) 3174, JP,Pt = 3653 Hz) ppm.
= 49 Hz, P(2)] ppm. 195Pt{1H} NMR (86 MHz, CD2Cl2, 295 K): δ
X-ray Data Collection, Structure Solution and Refinement of 5:[34]
Crystal data, parameters for intensity data collection and conver-
gence results are compiled in Table 3. A yellow platelet of approxi-
mate dimensions 0.20×0.11×0.04 mm was studied at room tem-
perature with a BRUKER-AXS SMART APEX diffractometer.
An empirical absorption correction[35] was applied before averaging
symmetry-related reflections. The structure was solved by direct
methods[36] and refined on F2.[37]
1
1
2
= –5524 [dtd, JPt(1),P(1) = 2469, JPt(1),P(2) = 5489, JPt(1),P(3)
=
49 Hz, Pt(1)] ppm.
Table 3. Crystal data and structure refinement for 5.
Empirical formula
Molecular mass
Temperature [K]
Wavelength [Å]
Crystal system
Space group
Unit cell dimensions
a [Å]
b [Å]
C50H94O2P4Pt2
1241.31
293(2)
0.71073
monoclinic
P21/c (no. 14)
NMR Spectroscopic Features for {(Cy2PH)Pt(µ-PCy2)2Pt-
[Cy2(tBuO)P]}(Pt–Pt) (10): Compound 10 was the main product
of reaction of 1 with NaOtBu (8 equiv.) in toluene at 50 °C. 1H
NMR (400 MHz, C6D6, 295 K): δ = 6.38 [m, 1JH(1),P(2) = 317 Hz, 2
H, H(1)]; 1.66 (s, 9 H, tBu) ppm. 31P{1H} NMR (161 MHz, C6D6,
11.1753(13)
21.220(2)
12.2712(14)
113.052(2)
2677.6(5)
2
1.540
5.4
1.9–28.4
6689
4198
6689/262
0.997
0.0453
0.0615
2.55, –1.08 (close to Pt)
2
2
1
295 K): δ = 235.8 [dd, JP(1),P(3) = 57, JP(1),P(2) = 53, JP(1),Pt(1)
=
c [Å]
2594, 1JP(1),Pt(2) = 2528 Hz, P(1)], 128.7 [dt, 3JP(3),P(2) = 78, 2JP(3),P(1)
β [°]
1
3
2
= 57, JP(3),Pt(2) = 5378 Hz, P(3)], 18.4 [dt, JP(2),P(3) = 78, JP(2),P(1)
V [Å3]
1
= 54, JP(2),Pt(1) = 4794 Hz, P(2)] ppm. 195Pt{1H} NMR (86 MHz,
Z
1
1
Dcalcd. [Mgm–3]
Absorption coeff. [mm–1]
θ Range for data coll. [°]
Independent reflections
Observed reflections
Data/parameters
Goodness-of-fit on F2
R[a] [I Ͼ 2σ(I)]
C6D6, 295 K): δ = –5492 [dt, JPt(1),P(1) = 2594, JPt(1),P(2)
=
1
1
4794 Hz, (1)]; –5445 [dt, JPt(2),P(1) = 2528, JPt(2),P(3) = 5378 Hz,
Pt(2)] ppm.
[b]
wR2 (all data)
Largest diff. peak/hole [eÅ–3]
2
2 2
[a] R = ∑||Fo| – |Fc||/∑|Fo|. [b] wR2 = [∑w(Fo – Fc ) /∑w(Fo2)2]1/2
.
Supporting Information: The H-31P HMQC NMR spectrum of 2,
the 31P{1H} NMR spectrum of [(Cy2PH)(Cl)Pt(µ-PCy2)Pt-
(Cy2PH)2](Pt–Pt), the comparison of the experimental 31P{1H}
NMR spectrum of 3 with that calculated, and the 31P{1H} NMR
spectrum of 9 are given as supporting information.
1
cis-[Pt(PHCy2)2(OPh)2] (11): Sodium phenoxide (0.116 g,
0.999 mmol) was added to a toluene suspension of cis-[Pt(PHCy2)2-
Cl2] (0.224 g, 0.338 mmol in 10 mL) and the mixture was stirred at
room temperature for 2 h. The resulting suspension was filtered,
giving a white solid and a yellow solution. The white solid was
washed with water, extracted with CH2Cl2 and precipitated with
toluene, affording 98 mg (41%) of pure cis-[Pt(PHCy2)2(Cl)(OPh)]
(12). The yellow filtrate was evaporated under reduced pressure.
The residue was redissolved in 4 mL of dichloromethane and n-
hexane added , which caused the precipitation of cis-[Pt(PHCy2)2-
(OPh)2] (11) as a white solid (0.155 g, 59%). Complex 11 was air
stable, very soluble in dichloromethane, toluene, scarcely soluble in
hexane. C36H56O2P2Pt (777.85): calcd. C 55.59, H 7.26; found C
Acknowledgments
Italian MIUR (PRIN 2004, project 2004030719_005) is gratefully
acknowledged for financial support. We thank Dr. A. Fiore for
experimental assistance, Dr. C. Hu for help with the X-ray experi-
ment and Prof. F. P. Fanizzi for helpful discussions.
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55.45, H 7.38. M.p. 129–131 °C (dec.). IR (nujol mull): νmax = 2333
˜
1
(m, P–H) cm–1. H NMR (400 MHz, CDCl3, 295 K): δ = 3.8 (m,
1JH,P = 367 Hz, PH) ppm. 31P{1H} NMR (161 MHz, CDCl3,
295 K): δ = 5.6 (s, JP,Pt = 3389 Hz) ppm. 195Pt{1H} NMR
1
1
(86 MHz, CDCl3, 295 K): δ = –4155 (t, JP,Pt = 3389 Hz) ppm.
cis-[Pt(PHCy2)2(Cl)(OPh)] (12): C30H51ClOP2Pt (720.20): calcd. C
50.03, H 7.14, Cl 4.92; found C 50.11, H 7.18, Cl 4.88. M.p.
Ͼ300 °C (dec.). IR (nujol mull): ν
= 2330, 2345 (m, P–H), 306
˜
max
(m, Pt–Cl) cm–1. 1H NMR (400 MHz, CDCl3, 295 K): δ = 3.83 (m,
2
1
1JH,P = 359, JH,Pt = 102 Hz, PH trans Cl), 3.67 (m, JH,P = 352,
Eur. J. Inorg. Chem. 2005, 4607–4616
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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V. Gallo et al.
FULL PAPER
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Received: June 7, 2005
Published Online: September 26, 2005
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