Reaction of platinum acetate with phosphines and molecular structure of trans-[Pt(OAc)2(PPh3)2]

Article abstract of DOI:10.1016/S0020-1693(03)00314-1

An improved synthesis of platinum acetate is reported in detail. This tetrameric complex reacts with PPh₃ or P-n-Bu₃ at room temperature to give the thermodynamically unstable bis-substituted trans-[Pt(OAc)₂L₂] complexes, which are not easily accessible via other routes. The structure of the new compound trans-[Pt(OAc)₂(PPh₃)₂] has been determined by X-ray analysis.

Full text of DOI:10.1016/S0020-1693(03)00314-1

Inorganica Chimica Acta 355 (2003) 399ꢀ403
/
www.elsevier.com/locate/ica
Note
Reaction of platinum acetate with phosphines and molecular
structure of trans-[Pt(OAc)2(PPh3)2]
Marino Basato a,*, Andrea Biffis a, Gianluca Martinati a, Cristina Tubaro a,
Alfonso Venzo a, Paolo Ganis a, Franco Benetollo b
a Dipartimento di Chimica Inorganica, Metallorganica e Analitica, Universita` di Padova, and ISTM-CNR, via Marzolo 1, I-35131 Padua, Italy
b ICIS-CNR, Corso Stati Uniti 4, I-35127, Italy
Received 24 March 2003; accepted 24 April 2003
Abstract
An improved synthesis of platinum acetate is reported in detail. This tetrameric complex reacts with PPh3 or Pꢀ
/n-Bu3 at room
temperature to give the thermodynamically unstable bis-substituted trans-[Pt(OAc)2L2] complexes, which are not easily accessible
via other routes. The structure of the new compound trans-[Pt(OAc)2(PPh3)2] has been determined by X-ray analysis.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Platinum acetate; Platinum(II) complexes; Phosphino complexes; Acetato complexes; trans Complexes
1. Introduction
[Pt4(OAc)8] was obtained, albeit in low yield (20%), by
chromatography on Sephadex LH-20 using acetic acid
as the eluent. 1H and 195Pt NMR spectra of the product
in CDCl3 show the expected signals of the methyl
protons out (2.01 ppm) and in (2.44 ppm) the plane of
the four platinum centers [9], and a unique 195Pt signal
The chemistry of Pt(II) complexes with carboxylate
ligands is rather limited. This is not surprising if one
considers that the logical starting reagent, platinum
acetate, is not commercially available; furthermore, its
reported synthesis can produce explosive mixtures and is
at ꢁ
detectable in the 1D spectrum, are clearly observed in
the 1Hꢀ13C 2D heterocorrelated experiments [11]1
[1Hꢀ13 21.57 (CH3COOꢁ out of
C, d (ppm): 2.01ꢀ
131 Hz), 2.44ꢀ
22.35 (CH3COOꢁ in
131 Hz), 2.44ꢀ
188.12 (CH3COOꢁ in
650 Hz), 2.01ꢀ
193.71 (CH3COOꢁ out of
740 Hz).
/
589 ppm [10]. The 13C resonances, which are not
characterized by low irreproducible yields [1ꢀ3]. The
/
/
known carboxylate complexes mainly contain mono-
and bidentate phosphines as additional ligands: in fact,
they are synthesized by oxidation of PtL4 phosphino
/
/
3
plane, JPtC
ꢂ
/
/
3
complexes [4ꢀ
6], or via a Clꢁ/O2CRꢁ exchange by
/
plane, JPtC
ꢂ
/
/
2
plane JPtC
plane JPtC
ꢂ
/
/
treating the corresponding chloro-complexes with silver
carboxylate [7]. The more straightforward synthesis for
this type of complexes, i.e. the reaction of platinum
acetate with phosphines, requires the availability of a
convenient synthetic procedure for the platinum salt.
An alternative method is described in an ICI Patent
and is based on treatment of PtCl4 with silver acetate in
acetic acid at reflux [8]. In our experience, the isolated
2
ꢂ
/
2. Results and discussion
We have developed a more convenient synthesis in
which PtCl4 is replaced by PtCl2 [12]. Treatment of
PtCl2 with 2 equiv. of Ag(OAc) in acetic acid at reflux
for 45 min gives a pure sample of platinum acetate in
1
solid was always a mixture, as indicated by its H and
195Pt NMR spectra in CDCl3; however, a pure sample of
1
* Corresponding author. Tel.: ꢃ
8275 223.
E-mail address: marino.basato@unipd.it (M. Basato).
/
39-049-8275 217; fax: ꢃ
/
39-049-
HMQC with bird sequence and quadrature along F1 was achieved
using the TPPI method for the H-bonded atoms, HBBC for the
carbonyl ones.
0020-1693/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00314-1

400
M. Basato et al. / Inorganica Chimica Acta 355 (2003) 399ꢀ403
/
fair yield (45ꢀ55%), with Pt metal as the main by-
/
product. Under the adopted experimental conditions
[Pt4(OAc)8] is solvated by 2 mol of acetic acid, whose
1
presence strongly affects the H NMR spectrum of the
compound. In CDCl3 solution the two peaks of the
methyl protons at 2.01 and 2.44 ppm appear actually
superimposed to a broad large band centered at 2.25
ppm; however, only the expected signal at ꢁ
observed in the 195Pt spectrum (investigated range from
100 to ꢁ4600 ppm).
/
589 ppm is
/
[Pt4(OAc)8] reacts quickly in chloroform at room
temperature with phosphines having different steric and
electronic properties. The reaction involves the degrada-
tion of the tetrameric structure and yields the mono-
nuclear [Pt(OAc)2L2] complexes (Lꢂ
/
PPh3, Pꢀn-Bu3,
/
1/2 Ph2PCH2PPh2) when the ligand is used in a Pt/L 1/2
molar ratio. NMR data indicate that the isolated bis-
substituted complexes with monophosphines are trans
isomers; the 1JPtP constants (3080 Hz for PPh3 and 2760
Fig. 1. ORTEP plot of [Pt(OAc)2(PPh3)2] with atom labeling. Selected
˚
bond distances (A) and bond angles (8): Ptꢀ
C(25)ꢂ1.836(8), PtꢀP(2)ꢂ2.313(2), P(2)ꢀC(31)ꢂ
O(1)ꢂ2.032(5), O(1)ꢀC(37)ꢂ1.31(1), PtꢀO(4)ꢂ2.044(5), C(37)ꢀ
O(2)ꢂ1.22(1), P(1)ꢀC(1)ꢂ1.823(8), C(37)ꢀC(38)ꢂ1.51(1), P(1)ꢀ
C(7)ꢂ1.835(8), O(4)ꢀC(39)ꢂ1.31(1), P(1)ꢀC(13)ꢂ1.839(9), C(39)ꢀ
O(3)ꢂ1.21(1), P(2)ꢀC(19)ꢂ1.819(8), C(39)ꢀC(40)ꢂ1.50(1); P(1)ꢀ
PtꢀP(2)ꢂ167.8(7), P(2)ꢀPtꢀO(1)ꢂ93.5(2), P(1)ꢀPtꢀO(1)ꢂ91.3(2),
P(2)ꢀPtꢀO(4)ꢂ84.9(2), P(1)ꢀPtꢀO(4)ꢂ90.1(2), O(1)ꢀPtꢀO(4)ꢂ
178.3(2), O(1)ꢀC(37)ꢀO(2)ꢂ124.0(9), O(4)ꢀC(39)ꢀO(3)ꢂ126.0(8),
O(1)ꢀC(37)ꢀC(38)ꢂ113.1(8), O(4)ꢀC(39)ꢀC(40)ꢂ112.3(7), O(2)ꢀ
C(37)ꢀC(38)ꢂ122.8(9), O(3)ꢀC(39)ꢀC(40)ꢂ121.8(8).
/
P(1)ꢂ
/
2.327(2), P(2)ꢀ
/
/
/
/
/
/
1.829(8), Ptꢀ
/
/
/
/
/
/
/
Hz for Pꢀ/n-Bu3) are in the typical range for trans
/
/
/
/
/
/
phosphino complexes (2500ꢀ/3000 Hz) and, in addition,
/
/
/
/
/
/
the resonances of ortho and meta phenyl carbons appear
as triplets. This behavior is characteristic of a trans
arrangement of the two phosphines; in fact, the coupling
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2
/
/
/
/
/
/
constant JPPtrans is so high that the carbon nuclei
experience the effect of both phosphorus atoms (virtual
/
/
/
/
/
/
/
/
/
/
/
/
coupling). The cis
geometry observed with
Ph2PCH2PPh2 is imposed by the chelating properties
of this diphosphine.
The molecular structure of [Pt(OAc)2(PPh3)2] is
shown in Fig. 1 with the atom-labeling scheme used.
X-ray structure analysis of trans-[Pt(OAc)2(PPh3)2]:
1/2ꢁ
Torsion angles (8): Ptꢀ
P(2)ꢀC(31)ꢀC(36)ꢀ59.0(7),
16.7(7), PtꢀP(2)ꢀC(25)ꢀ
C(13)ꢀC(14)ꢀ45.7(7), Ptꢀ
P(1)ꢀPtꢀO(4)ꢀC(39)ꢀ80.8(5), P(2)ꢀ
84.2(6), P(1)ꢀPtꢀO(1)ꢀC(37)ꢀ106.9(5), P(2)ꢀ
C(39) 110.4(5); the reciprocal orientation of the two
phosphines corresponds almost exactly to a staggered
conformation. In this way, the contact interactions
between faced phenyl groups are minimized [13]. In
agreement with the observed molecular pseudo-symme-
try C2, the two acetato groups are disposed in a cisoid
arrangement with respect to the coordination plane of
Pt. A rough, yet reliable conformational analysis of the
complex has shown that any different reciprocal ar-
rangement of the two acetato groups and/or of the two
/
z); O(2)ꢀ ꢀ ꢀH(33)ƒ 2.71 (ƒ at 1ꢁ
P(1)ꢀC(1)ꢀC(6)ꢀ
PtꢀP(1)ꢀ
C(30)ꢀ55.4(7),
P(2)ꢀC(19)ꢀC(24)ꢀ
PtꢀO(1)ꢀ
Ptꢀ
/
x, 1ꢁ
62.7(7), Ptꢀ
C(7)ꢀC(8)ꢀ
PtꢀP(1)ꢀ
42.0(7),
C(37)ꢀ
O(4)ꢀ
/
x, 1ꢁ
/
z).
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C40H36O4P2Pt, Mrꢂ837.76, monoclinic, space group
/
/
/
/
/
/
/
/
/
˚
˚
P21/c, aꢂ
/
11.830(3) A, bꢂ
94.69(3)8, Zꢂ4, Vꢂ
cmꢁ3, mꢂ
/
15.158(3) A, cꢂ
/
19.632(4)
3
3509(1) A , rcalc
/
/
/
/
/
/
/
˚
˚
A, bꢂ
/
/
/
ꢂ
/1.586 g
˚
/
4.130 mmꢁ1, Mo Ka (lꢂ
293(2) K. Philips PW1100 (Febo System); structure
solved by heavy atoms methods and refined with
/
0.71073 A), Tꢂ
/
SHELXL-97. Reflections collectedꢂ
servedꢂ6422 [I ꢀ2s(I)]; R1ꢂ0.048 (R1ꢂ
ajFoj); wR2ꢂ0.104 (wR2ꢂ
/
6948; reflections ob-
ajFojꢁjFcj/
[a w(Fo2ꢁFc2)2/
/
/
/
/
/
/
/
/
a w(Fo2)2]1/2). All the bond lengths and angles are in
ranges typical for comparable molecular groupings.
The coordination around Pt is only slightly distorted
four-planar, the highest deviations being P(2)ꢀ
/
PtꢀP(1)
/
PPh3 groups would lead to highly repulsive intramole-
˚
2.00 A,
167.8(2)8 and P(2)ꢀPtꢀO(4) 84.9(2)8. The triphenylpho-
/
/
cular contact distances, namely: Oꢀ ꢀ ꢀHB
/
sphine groups in trans position assume an intrinsically
asymmetric propeller-shaped geometry. They exhibit the
same configuration and are apparently related by a local
pseudo C2 symmetry with the twofold axis almost
orthogonal to the coordination plane of Pt. Intramole-
˚
˚
2.8 A. Nonetheless, even
Cꢀ ꢀ ꢀHB
/
2.10 A and Cꢀ ꢀ ꢀCB
/
in the observed molecular structure very short contact
distances are present. However, they appear to be of
quite different nature. In fact, values such as
˚
˚
˚
O(3)ꢀ ꢀ ꢀH(8) 2.72 A and O(1)ꢀ ꢀ ꢀH(36) 2.72 A, but also
cular non bonded distances (A): O(1)ꢀ ꢀ ꢀH(14) 2.28,
˚
˚
H(30)ꢀ ꢀ ꢀO(3) 3.04 A and H(8)ꢀ ꢀ ꢀO(2) 2.93 A, fall in the
O(3)ꢀ ꢀ ꢀH(8) 2.72, O(1)ꢀ ꢀ ꢀH(36) 2.72, O(3)ꢀ ꢀ ꢀH(30)
range of now generally accepted weak bond interactions
3.04, O(2)ꢀ ꢀ ꢀH(8)ꢂ2.93, O(4)ꢀ ꢀ ꢀH(24) 2.38. Intermole-
/
˚
of type Cꢀ
/
Hꢀ ꢀ ꢀX (X acceptorꢂ
/
O, N); the bond angles
1408) are in agreement with this as-
cular non bonded distances (A): O(2)ꢀ ꢀ ꢀH(22) 2.61,
O(2)ꢀ ꢀ ꢀH(23)? 2.71, O(3)ꢀ ꢀ ꢀH(22)? 2.88 (? at x, 1/2ꢁy,
/
Cꢀ
/
Hꢀ ꢀ ꢀX (110ꢀ
/

M. Basato et al. / Inorganica Chimica Acta 355 (2003) 399ꢀ
/403
401
sumption as well [14]. In contrast, the distances and
˚
The results obtained indicate that platinum acetate is
a very convenient reagent for the room temperature
synthesis of trans bis-phosphine complexes. The high
trans effect of the phosphine ligand appears responsible
for the observed geometry and for the degradation of
the tetrameric structure of the platinum salt. Heating of
the trans complexes in deuteroacetic acid at 90 8C
angles O(1)ꢀ ꢀ ꢀH(14) 2.28 A (O(1)ꢀ ꢀ ꢀH(14)ꢀ
/
C(14) 1448)
˚
and O(4)ꢀ ꢀ ꢀH(24) 2.36 A (O(4)vH(24)ꢀ
/
C(24) 1448), are
close to the expected values for typical hydrogen-bonds
[15]. All of these bond interactions play a significant role
in the stabilization of the observed molecular structure.
The complex undergoes an easy rearrangement to a
cis configuration by moderate heating in polar solvents.
In fact, the platinum cis-bisphosphino complexes are
stabilized, compared with the trans ones, by stronger
induces trans ꢀcis isomerization without any evidence
/
of the formation of reduction products. This last aspect
confirms the difference of reactivity between platinum
and palladium complexes; in fact, bis-carboxylato bis-
phosphine palladium complexes are good catalysts for
the Heck reaction, due to their ability to give on heating
catalytically active palladium zero species [17].
PtꢀP bonds and better solvent effects, which may
/
overcome the less favourable electrostatic interactions
between the metal and the ligand set [16].
The reactivity of platinum acetate toward phosphines
has been checked also with the smaller phosphine
PMe2Ph at different molar ratios in deuterated acetic
acid, at room temperature and at 90 8C (Scheme 1).
It is interesting to note that: (i) reaction at room
3. Experimental
temperature gives the kinetically favored trisꢀ
no complex [Pt(OAc)L3](OAc) even at low L/Pt molar
ratios (0.5ꢀ1.0) together with unreacted platinum ace-
/
phosphi-
3.1. Synthesis
/
tate; (ii) heating of these mixtures at 90 8C affords the
thermodynamically stable monosubstituted complexes
[Pt(OAc)2L]1,2 and the bis-substituted cis-[Pt(OAc)2L2],
in relative amounts dependent on the total phosphine
content; (iii) heating induces conversion of the trans into
the cis isomer; (iv) at a Pt/L 1/2 molar ratio the mixture
of platinum acetate, bis- and tris-substituted complexes
formed at room temperature is converted upon heating
into the expected trans- and cis-[Pt(OAc)2L2]; (v) the
small PMe2Ph (Tolman’s cone angle 1228 compared to
3.1.1. Platinum acetate
A mixture of PtCl2 (1.02 g, 3.85 mmol) and Ag(OAc)
(1.35 g, 8.10 mmol) in acetic acid (60 ml) was maintained
at reflux under stirring for 45 min. The precipitated
AgCl was filtered off at room temperature (r.t.) and the
resulting blue solution was evaporated at reduced
pressure. The solid was dissolved with dichloromethane
(20 ml) and filtered over celite to eliminate traces of
residual silver chloride and some metallic platinum. The
blue solid obtained after solvent removal was treated
with diethyl ether, filtered and dried under vacuum (0.65
1328 for Pꢀ
/
n-Bu3 and 1458 for PPh3) easily forms the
dicationic tetraphosphino complex [Pt(PMe2Ph)4]2ꢃ
,
g, 47% yield calculated on [Pt4(OAc)8]×
Calc. for C20H32O20Pt4: C, 17.50; H, 2.34. Found: C,
17.20; H, 2.16%.
/
2HOAc). Anal.
whereas with the more hindering PPh3 only two
phosphines can be coordinated to the platinum centre.
Scheme 1. Major products of the reaction between [Pt4(OAc)8] (Pt4) and PMe2Ph (L) at different Pt/L ratios, in CD3COOD. In this solvent OAc
indicates deutero acetate.

402
M. Basato et al. / Inorganica Chimica Acta 355 (2003) 399ꢀ403
/
3.1.2. trans-[Pt(OAc)2(PPh3)2]
phosphine was added directly, in successive steps, to a
solution of [Pt4(OAc)8]×
2HOAc (ca. 10ꢁ2 mol dmꢁ3) to
A solution of [Pt4(OAc)8]×
/
2HOAc (75 mg, 0.054
/
mmol) and PPh3 (130 mg, 0.48 mmol) in chloroform
(30 mL) was stirred at r.t. for 3 h, during which time the
color changed from deep blue to orange. The solvent
was evaporated at reduced pressure; the resulting yellow
solid was treated with diethyl ether and filtered (120 mg,
66% yield). Anal. Calc. for C40H36O4P2Pt: C, 57.36; H,
4.30. Found: C, 57.32; H, 4.22%. NMR data; 1H, d
reach the following Pt/L ratios 2/1, 1/1, 1/2, 1/3, and 1/4.
The 1H and 31P NMR spectra were recorded at r.t.
immediately after the addition of the phosphine and
after heating of the resulting solution at 90 8C for 4 h.
The major products for each investigated Pt/L molar
ratios were summarised in Scheme 1.
The tris-substituted complex [Pt(OAc)(PMe2-
Ph)3](OAc) possesses two equivalent phosphorous do-
nor atoms in trans to each other and a ‘middle’
phosphorous coupled to those in cis positions. The 31P
(ppm): 0.89 (s, 3H, CH3COOꢁ), 7.19ꢀ
/
7.77 (m, 15H,
134.79 (Ph),
3080 Hz);
3080 Hz).
Ph); 13C: 21.12 (s, CH3COOꢁ), 128.11ꢀ
/
175.92 (s, CH3COOꢁ); 31P: 14.55 (s, JPtP
ꢂ
/
1
1
195Pt (vs. [PtCl6]2ꢁ ꢂ
/
0): ꢁ
/
2910 (t, JPtP
ꢂ
/
peak at ꢁ
can be assigned to the central phosphorous (Pa) and that
at ꢁ 2480 Hz) to the
0.1 ppm (d, 2JPP 22.8 Hz, 1JPtP
/
25.4 ppm (t, 2JPP
ꢂ
/
22.8 Hz, 1JPtP
ꢂ
/
3420 Hz)
Crystals for X-ray analysis were obtained by slow
evaporation of an acetonitrile solution. Further NMR
data in CDCl3: 13C, d (ppm): 21.12 (s, CH3COOꢁ),
/
ꢂ
/
ꢂ
/
remaining two phosphorous atoms (Pb), on the basis of
1
multiplicity, integration (1:2) and JPtP coupling con-
3
128.1 (t, m-C6H5, JPC
ꢂ
/
5.3 Hz), 130.4 (s, p-C6H5),
6.5 Hz), 175.9 (s, CH3COOꢁ).
H)], 1660 and 1435
2
134.8 (t, o-C6H5, JPC
ꢂ
/
FTIR (KBr, cmꢁ1): 3047 [n(Cꢀ
/
stants. The pattern of these signals is characteristic of
[n(CO2ꢁ)], 1481, 1284, 1097, 744, 692. MS (ESI,
capillary voltage 4.5 kV, capillary temp. 200 8C): m/z
778 ([Pt(OAc)(PPh3)2]ꢃ).
trisꢀphosphino complexes [18]. NMR data in
/
2
CD3COOD: 1H, d (ppm): 1.78 (t, JPH
ꢂ
/
3.5 Hz,
8 (PPh);
19.7 Hz, PaCH3), 15.8 (d, 1JPC
72.0
Hz, PbCH3), 128.7 (d, 2JPC
12 Hz, Pb(o-Ph)), 129.4 (t,
3JPC
5.3 Hz, Pa(m-Ph)), 129.6 (d, JPC
Pb(m-Ph)), 131.2 (t, JPC
p-Ph), 132.1 (d, 4JPC
(vs.[PtCl6]2ꢁ ꢂ
0 ppm), ꢁ
1JPtP
2480 Hz).
Two singlets in the 31P NMR spectra at ꢀ
(1JPtP 26.2 (1JPtP
4080 Hz) and ꢀ 4400 Hz), observed
2
PaCH3), 1.53 (d, JPH
ꢂ
/
11 Hz, PbCH3), 7.4ꢀ
/
13C, 12.1 (t, 1JPC
ꢂ
/
ꢂ
/
ꢂ
/
3.1.3. trans-[Pt(OAc)2(Pꢀ
n-Butylphosphine (0.115 g, 0.57 mmol) was added to
a solution of [Pt4(OAc)8]×2HOAc (0.095 g, 0.07 mmol)
/n-Bu3)2]
3
ꢂ
/
ꢂ10.4 Hz,
/
2
ꢂ6.2 Hz, Pa(o-Ph)), 131.8 (s,
/
/
in chloroform (25 ml); the mixture was left under
stirring at r.t. for 3 h, during which time the color
changed from deep blue to yellow. The solution was
then evaporated to dryness, to give an orange oil. Anal.
Calc. for C28H60O4P2Pt: C, 46.88; H, 8.36. Found: C,
ꢂ
/
2.9 Hz, p-Ph); 195Pt
1
/
/
4910 (dt, JPtP
ꢂ
/3420 Hz,
ꢂ
/
/
24.7
ꢂ
/
/
ꢂ
/
1
47.57; H, 9.07%. NMR data in CDCl3: H, d (ppm):
0.7ꢀ
2.1 (cm, butyl and acetoxy protons); 13C: 13.7 (s),
in the heated solution with Pt/L 2/1, are attributed to the
mono-substituted complexes [Pt(OAc)2L]1,2 on the basis
of the ESI MS spectrum, which shows two peaks at m/z
/
21.0 (t), 24.4 (t), 25.6 (s), 27.6 (s), 176.9 (CH3COOꢁ);
1
31P: 8.12 (s, JPtP
ꢂ
/
2760 Hz); 195Pt (vs.[PtCl6]2ꢁ ꢂ
0
/
937
([Pt(CD3COO)2(PMe2Ph)]2(Naꢃ))
and
480
1
2932 (t, JPtP
([Pt(CD3COO)2(PMe2Ph)](Naꢃ)). The different nucle-
arity of the fragments was confirmed also by the analysis
of the isotopic pattern of the two metal clusters.
The trans- and cis-[Pt(OAc)2(PMe2Ph)2] were identi-
ppm): ꢁ
/
ꢂ2760 Hz).
/
3.1.4. [Pt(OAc)2(Ph2PCH2PPh2)]
The reaction between platinum acetate and
Ph2PCH2PPh2 was studied in CDCl3, recording the 31P
1
and H NMR spectra. The diphosphine (0.016 g, 0.04
1
fied on the basis of the JPtP constants and of the
resonances of the phosphine methyl protons, which
appeared as triplets or doublets in the trans or cis
geometry respectively. cis-[Pt(OAc)2(PMe2Ph)2]; NMR
mmol) was added to a solution of [Pt4(OAc)8]×
/2HOAc
(0.015 g, 0.01 mmol) in deuterated chloroform. The
color of the solution changed immediately from deep
1
2
data in CD3COOD: H, d (ppm): 1.67 (d, JPH
1
20.8(s, JPtP
ꢂ
/
11.3
blue to orange. NMR data in CDCl3: 1H, d (ppm): 1.96
Hz, PCH3), 7.4ꢀ
/
8.0 (PPh); 31P, ꢁ
Hz). trans-[Pt(OAc)2(PMe2Ph)2]; NMR data in
/
ꢂ
/
3700
2
(s, 3H, CH3COOꢁ), 4.18 (t, 1H, CH2, JPH
ꢂ
ꢂ
/
9 Hz),
1
68.6 (s, JPtP
7.00ꢀ
/
7.82 (m, 10H, Ph); 31P: ꢁ
Hz). These data were in agreement with those reported
in Ref. [5].
/
/3460
CD3COOD: 1H, d (ppm): 1.73 (t, JPH
ꢂ
/
3.6 Hz,
2
1
3.8 (s, JPtP
PCH3), 7.4ꢀ
/
8 (PPh); 31P, ꢁ
The dicationic tetra-phosphino complex [Pt(PMe2-
/
ꢂ
/
2680 Hz).
1
12.8 (s, JPtP
Ph)4](OAc)2 presents a singlet at ꢁ
/
ꢂ2320
/
3.2. Reaction of [Pt4(OAc)8] (Pt4) with PMe2Ph (L)
at different Pt/L ratios
Hz); these values are in agreement with those reported in
literature for the same cation [19].
The acetato groups rapidly exchange with deuterated
acetic acid, so that the resonances of their methyl
protons can not be detected.
The reaction between [Pt4(OAc)8]×
PMe2Ph was followed in deuterated acetic acid at
different Pt/L molar ratios, in a NMR tube. The
/
2HOAc and

M. Basato et al. / Inorganica Chimica Acta 355 (2003) 399ꢀ
/403
403
[6] C. Eaborn, K.J. Odell, A. Pidcock, J. Chem. Soc., Dalton Trans.
(1979) 758.
4. Supplementary material
[7] A.L Tan, P.M.N. Low, Z.-Y. Zhow, W. Zheng, B.-M. Wu,
T.C.W. Mak, T.S.A. Hor, J. Chem. Soc., Dalton Trans (1996)
2207.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 203517. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
[8] D. Wright, Br. Patent 1214552, Imperial Chemical Industries
Ltd., 1970.
[9] T. Yamaguchi, Y. Sasaki, A. Nagasawa, T. Ito, N. Koga, K.
Morokuma, Inorg. Chem. 28 (1989) 4312.
1EZ, UK (fax: ꢃ44-1223-336-033; e-mail: depos-
/
[10] T. Yamaguchi, K. Abe, T. Ito, Inorg. Chem. 33 (1994) 2689.
[11] (a) A. Bax, S. Subramanian, J. Magn. Reson. 67 (1986) 565;
(b) G. Otting, K. Wuthrich, J. Magn. Reson. 76 (1988) 569;
¨
it@ccdc.cam.ac.uk or www: http://www.ccdc.cam.a-
c.uk).
(c) G. Drobny, A. Pines, S. Sinton, D. Weitekamp, D. Wemmer,
Faraday Symp. Chem. Soc. 13 (1979) 49;
(d) S. Bax, M.F. Sumers, J. Am. Chem. Soc. 108 (1986) 2093.
[12] This reaction was suggested, without any experimental detail and
product characterization in: P. Braunstein, B. Oswald, A.
Tiripicchio, F. Ugozzoli, J. Chem. Soc., Dalton Trans. (2000)
2195.
Acknowledgements
We thank Mr. A. Ravazzolo for skilled technical
assistance and Dr. R. Seraglia for ESI measurements.
[13] R. D’Amato, A. Furlani, M. Colapietro, G. Portalone, M.
Casalboni, M. Falconieri, M.V. Russo, J. Organomet. Chem.
627 (2001) 13.
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