(Phosphido)platinum complexes by sodium-promoted reaction of cis-PtCl2(PHCy2)2 - Synthesis and crystal structure of [trans-Pt(PCy2H)2(PCy2)Cl], a rare example of a terminal (phosphido)platinum(II) complex

Article abstract of DOI:10.1002/1099-0682(200205)2002:5<1210::AID-EJIC1210>3.0.CO;2-3

cis-PtCl₂(PHCy₂)₂ (1) reacts at 0°C in toluene with sodium metal to give the dinuclear Pt^I complexes cis-[(PHCy₂)-(H)Pt(μ-PCy₂)]₂ (2) and [(PHCy₂)(Cl)Pt(μ-PCy₂)Pt (PHCy₂)₂]-(Pt-Pt) (3). On standing in solution, complex 3 isomerizes to trans-[(PHCy₂)(Cl)Pt(μ-PCy₂) ₂Pt(PHCy₂)(H)] (4). When treated with sodium at room temperature, complex 3 transforms into [Pt(μ-PCy₂)(PHCy₂)]₂(Pt-Pt) (5). The sodium reduction of 1 carried out at room temperature leads to the direct formation of the phosphido bridged dinuclear complex [Pt(μ-PCy₂)(PHCy₂)]₂(Pt-Pt) (5) along with the mononuclear platinum(II) complex [trans-Pt(PCy₂H)₂(PCy₂)Cl] (6). Complex 6, which has also been obtained by reaction of 1 with LiPCy₂, unambiguously shows by single-crystal X-ray diffraction the presence of a pyramidal terminal phosphido ligand. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200205)2002:5<1210::AID-EJIC1210>3.0.CO;2-3

FULL PAPER
(Phosphido)platinum Complexes by Sodium-Promoted Reaction of cis-
PtCl2(PHCy2)2 ؊ Synthesis and Crystal Structure of [trans-
Pt(PCy2H)2(PCy2)Cl], a Rare Example of a Terminal (Phosphido)platinum(II)
Complex
Piero Mastrorilli,*[a] Cosimo F. Nobile,[a] Francesco P. Fanizzi,[b] Mario Latronico,[c]
Chunhua Hu,[d] and Ulli Englert[d]
Keywords: Platinum / P ligands / Terminal phosphides / Hydrides / Small ring systems
cis-PtCl2(PHCy2)2 (1) reacts at 0 °C in toluene with sodium
metal to give the dinuclear PtI complexes cis-[(PHCy2)-
(H)Pt(µ-PCy2)]2 (2) and [(PHCy2)(Cl)Pt(µ-PCy2)Pt(PHCy2)2]-
(Pt−Pt) (3). On standing in solution, complex 3 isomerizes to
[Pt(µ-PCy2)(PHCy2)]2(Pt−Pt) (5) along with the mononuclear
platinum(II) complex [trans-Pt(PCy2H)2(PCy2)Cl] (6). Com-
plex 6, which has also been obtained by reaction of 1 with
LiPCy2, unambiguously shows by single-crystal X-ray dif-
fraction the presence of a pyramidal terminal phosphido li-
gand.
trans-[(PHCy2)(Cl)Pt(µ-PCy2)2Pt(PHCy2)(H)]
(4).
When
treated with sodium at room temperature, complex 3 trans-
forms into [Pt(µ-PCy2)(PHCy2)]2(Pt−Pt) (5). The sodium re-
duction of 1 carried out at room temperature leads to the dir-
(
Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
ect formation of the phosphido bridged dinuclear complex 2002)
Introduction
respectively, depending on the diphosphane and on the re-
action conditions.[2] Phosphido-bridged dinuclear metal(I)
complexes have been accessed by sodium reduction of Ni(P-
Cy2Ph)2Cl2,[3] Pt(PHtBu2)2Cl2,[4] and M(PHCy2)2Cl2 (M ϭ
Ni, Pd).[5] Moreover, when the sodium reaction of
Pd(PHCy2)2Cl2 was carried out at 0 °C, the isolation of
[(PHCy2)(Cl)Pd(µ-PCy2)Pd(PHCy2)2](PdϪPd) (7) was
achieved (Scheme 1).
The reaction of sodium metal with phosphanyl divalent
group-10 halide complexes has been widely used to access
molecules in which a transition metal atom exhibits a low-
valent and somehow unusual oxidation state. In particular,
NiP2X2 (P ϭ PEt3, PnBu3, PEt2Ph; X ϭ Cl, Br) was re-
duced under argon to the zero-valent tetracoordinated spe-
cies NiP4, whereas Ni(PCy3)2X2 (X ϭ Cl, Br) gave
Ni(PCy3)3 or [NiX(PCy3)2]2.[1] The chelating diphosphane
complexes Ni(dp)Cl2 [dp ϭ 1,2-bis(diphenylphosphanyl)e-
thane (dppe), 1,2-bis(diethylphosphanyl)ethane (depe), 1,2-
bis(dicyclohexylphosphanyl)ethane (dcpe), 1,3-bis(dicy-
clohexylphosphanyl)propane (dcpp), 1,4-bis(dicyclohexyl-
phosphanyl)butane (dcpb)] afforded the 14- (dp ϭ dcpe,
dcpp, dcpb), 16- (dp ϭ dcpe, dcpb), or 18-electron (dp ϭ
dppe, depe, dcpe) complexes Ni(dp), Ni2(dp)3, and Ni(dp)2,
[a]
Centro di Studi C.N.R. M.I.S.O. and Dipartimento di
Ingegneria Civile e Ambientale del Politecnico di Bari,
Via Orabona 4, 70125 Bari, Italy
Fax: (internat.) ϩ 39-080/596-3611
E-mail: p.mastrorilli@poliba.it
[b]
Dipartimento di Scienze
e
Tecnologie Biologiche ed
Scheme 1
`
Ambientali, Universita degli Studi di Lecce,
Via Monteroni, 73100 Lecce, and
Consortium C.A.R.S.O., Cancer Research Centre,
70010 Valenzano, Italy
In this paper we describe the reactivity of cis-
Pt(PHCy2)2Cl2 (1) towards sodium metal which was found
to depend on the reaction temperature. At 0 °C the phos-
[c]
`
Dipartimento di Ingegneria e Fisica dell’Ambiente, Universita
della Basilicata,
C. da Macchia Romana, 85100 Potenza, Italy
Institut für Anorganische Chemie der RWTH,
Prof.-Pirlet-Str. 1, 52074 Aachen, Germany
phido-bridged
dinuclear
platinum
species
cis-
[d]
[(PHCy2)(H)Pt(µ-PCy2)]2 (2) and [(PHCy2)(Cl)Pt(µ-
1210
WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0505Ϫ1210 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 1210Ϫ1218

(Phosphido)platinum Complexes
FULL PAPER
PCy2)Pt(PHCy2)2](PtϪPt) (3) were formed, whereas a mix- signal at δ ϭ Ϫ170.6 (phosphide P1Cy2) splits into a triplet
ture of [Pt(µ-PCy2)(PHCy2)]2(PtϪPt) (5) and the mononu- of doublets due to the additional coupling with the trans
clear
(phosphido)platinum(II)
complex
[trans- hydride ligands [2J(P-H) ϭ 143 Hz].
Pt(PHCy2)2(PCy2)Cl] (6) was obtained when the reaction
was carried out at room temperature.
Table 1. NMR parameters for complex 2 ([D6]benzene, 295 K);
chemical shifts (bold) are in ppm; coupling constants (normal) are
in Hz
Results and Discussion
The reaction of cis-PtCl2(PHCy2)2 (1) with sodium metal
carried out in toluene at 0 °C resulted in the formation of
two dinuclear complexes 2 and 3 in an approximately 4:1
ratio. Complex 2 is fairly stable in the air but air-sensitive
in aromatic solvents, where it easily dissolves. Taking ad-
vantage of insolubility in alcohols it was isolated as a white
powder from the reaction mixture by treatment with meth-
anol.
Complex 2 exhibits in the IR spectrum two characteristic
bands at 2299 and 1940 cmϪ1 due to PϪH and PtϪH
stretching, respectively. The 31P{1H} NMR spectrum of 2
recorded at room temperature consists of three signals, all
flanked by 195Pt satellites: two doublets (δ ϭ 24.8 and δ ϭ
Ϫ170.6) and a triplet of doublets (δ ϭ Ϫ123.0). The high-
P1
P2
P3
H1
Pt
P1
P2
P3
H1
Pt
؊170.6
ca. 0
104
143
1322
ca. 0
24.8
308
20
1968
104
308
؊123.0
9
143
20
9
Ϫ3.84
905
1322
1968
2118
905
2118
Ϫ4441
1
Finally, the value of J(Pt-H) (905 Hz) and the position
field signals at δ ϭ Ϫ123.0 and δ ϭ Ϫ170.6, which are of the PtϪH stretching band in the IR spectrum both indic-
mutually coupled [2J(P-P) ϭ 104 Hz], are typical for ate terminal coordination for the hydride ligands. The di-
bridging phosphides involved in four-membered rings,[6] meric structure of 2 formulated as cis-[(PHCy2)(H)Pt(µ-
and strongly support a dinuclear structure for 2, with two PCy2)]2 was also confirmed by the 195Pt{1H} NMR spec-
inequivalent phosphide groups bound to two platinum trum which consists of a doublet of doublets of doublets
atoms without PtϪPt linkage. Moreover, the pattern of the centred at δ ϭ Ϫ4441 [1J(Pt-P1) ϭ 1322, 1J(Pt-P2) ϭ
1
phosphide 31P signals (triplet of doublets and doublet) and 1968 Hz, and J(Pt-P3) ϭ 2118 Hz].
the value of the coupling constant between the phosphorus
The minor product obtained in the sodium reduction of
signal at δ ϭ Ϫ123.0 and that at δ ϭ 24.8 [J(P-P) ϭ 308 Hz] 1 at 0 °C, is a yellow-orange solid, the spectroscopic fea-
both suggest a symmetrical dimeric structure in which two tures and elemental analysis of which indicate the phos-
platinum atoms, each bearing a dicyclohexylphosphane li- phido-bridged platinum(I) complex [(PHCy2)(Cl)Pt(µ-
gand are bridged by two dicyclohexylphosphide groups. In PCy2)Pt(PHCy2)2](PtϪPt) (3), and represents the Pt ana-
the dimer the dicyclohexylphosphane ligands are cis with logue of the palladium complex 7. In the region of the PϪH
respect to each other and trans with respect to the bridging stretching the IR spectrum of 3 shows the convolution of
phosphide group resonating at δ ϭ Ϫ123.0. 1H and proton- two bands of relative intensities 2:1 centred at 2295 cmϪ1
coupled 31P NMR spectroscopy experiments together with and 2255 cmϪ1. The PtϪCl band was found at 301 cmϪ1
.
IR data indicate that, on each platinum atom, the cis posi- The 31P{1H} NMR spectrum of 3 recorded at room temp.
tions with respect to the terminal dicyclohexylphosphane shows signals centred at δ ϭ 185.5, 37, and 16 and is remin-
ligands are occupied by terminal hydride ligands. In iscent of that of 7.
addition to the resonances of aliphatic protons and a broad
Among these signals, the only well-resolved one is that
doublet which can be attributed to the hydrogen atom centred at δ ϭ 185.5 (Figure 1) which does not significantly
directly bound to P in the coordinated dicyclohexylphos- split in the proton coupled spectrum. This signal can be
1
1
phane [δ ϭ 4.50; J(P-H) ϭ 317 Hz], the H NMR spec- attributed to a bridging phosphide group involved in a
trum shows a doublet of doublet of doublets [J(P-H) ϭ 143, three-membered Pt2P ring[7] in which the two platinum
20, and 9 Hz] with 195Pt satellites centred at δ ϭ Ϫ3.84 atoms are inequivalent. The spectrum consists of a central
[1J(Pt-H) ϭ 905 Hz]. This latter signal could be attributed doublet of triplets due to isotopomer A, which does not
to two equivalent terminal hydride ligands, cis with respect contain 195Pt (43.8%) flanked by three different sets of satel-
to each other and trans with respect to the bridging phos- lites, two arising from isotopomers B and C (22.4% each),
phide group resonating at δ ϭ Ϫ170.6 as suggested by the which contain only one 195Pt nucleus and one due to isoto-
2
high value of J(P-H) (143 Hz).
pomer D (11.4%) which contains two 195Pt nuclei. The
In the proton-coupled 31P NMR spectrum the signal at coupling constants 2J(P-P) ϭ 231 and 26 Hz, which are cle-
δ ϭ Ϫ123.0 (phosphide P3Cy2, see Table 1 for numbering) arly seen in the signal of isotopomer A, indicate that the
remains substantially unchanged while the signal at δ ϭ phosphorus atom of the bridging phosphide group is
24.8 (phosphanes P2Cy2H) splits into a pseudo-triplet due coupled with a pseudo-trans- and two pseudo-cis-oriented
to the additional direct coupling 1J(P-H) ϭ 317 Hz, and the phosphorus nuclei. The sets of satellites arising from both
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218
1211

P. Mastrorilli, C. F. Nobile, F. P. Fanizzi, M. Latronico, C. Hu, U. Englert
FULL PAPER
isotopomers B and C appear as doublets of doublets of experiments showed that the signal at δ ϭ 37, which does
doublets. The couplings of P1 with the two inequivalent not change significantly by lowering the temperature down
1
platinum atoms gives the constants J(Pt2-P1) ϭ 3072 Hz to Ϫ38°C, splits into a broad doublet [2J(P1-P3) ϭ 231 Hz]
and 1J(Pt1-P1) ϭ 3911 Hz whereas the coupling with P2 and at high temperatures (Ͼ 50 °C) due to the coupling with
P4 gives 2J(P1-P2) ϭ 34 Hz and 2J(P1-P4) ϭ 22 Hz (see the bridging phosphide group. The broadness of this signal
Table 2 for P and Pt numbering). The third subset of signals at or below room temperature, can therefore be explained
due to the isotopomer D consists of a doublet of doublets in terms of hindered rotation around the P3ϪPt bond ori-
of doublets of multiplets. The relevant coupling constants ginating in a set of slowly interconverting rotamers.
1
1
are J(Pt2-P1) ϭ 3080 Hz and J(Pt1-P1) ϭ 3916 Hz. Inter-
For the related palladium complex 7 the signal of the
estingly, the central signal appears as a doublet of triplets PHCy2 ligand trans to the bridging phosphide group is al-
(instead of the expected ddd). This can be explained in ready a broad doublet at room temperature[5] and becomes
2
terms of the isotopomer A having either coincident JP,P or a very broad singlet by lowering the temperature down to
a greater linewidth of the signal with respect to B, C, and Ϫ38 °C (Figure 2). This is in agreement with a more pro-
D, due to difference in relaxation efficiency in different iso- nounced fluxionality of palladium with respect to plat-
topomers. The latter explanation is in agreement with high- inum complexes.
temperature spectra (82 °C) that also show the expected
ddd for isotopomer A.[8]
Figure 1. Phosphide region of the 31P{1H} NMR spectrum of 3
([D8]toluene, 202 MHz, 295 K); A: isotopomer with no 195Pt atoms;
B: isotopomer with NMR-active Pt1; C: isotopomer with NMR-
active Pt2; D: isotopomer with NMR-active Pt1 and Pt2
Table 2. NMR parameters for complex 3 ([D8]toluene, 295 K);
chemical shifts (bold) are in ppm; coupling constants (normal) are
in Hz
P1
P2
P3
P4
P1
P2
P3
P4
185.5
34
231
22
34
16.3
16
231
16
37
12
22
154
12
Figure 2. VT 31P{1H} NMR spectra of 3 and 7 in [D8]toluene; (a)
202 MHz; (b) 81 MHz
154
15.8
In the case of complex 3, P2 and P4 (the two phosphorus
atoms of the phosphane ligands cis to the bridging phos-
The other 31P{1H} NMR resonances of 3 are a very phide group) belong to a second-order spin system and a
broad signal centred at δ ϭ 37 and a broad multiplet direct analysis of the spectrum was not obtained. The
centred at δ ϭ 16. The signal at δ ϭ 37 can be attributed 31P{1H} NMR spectrum simulation for the isotopomer
to P3 of the dicyclohexylphosphane pseudo-trans to the containing no 195Pt (ABMX spin system, A and B being P2
phosphide group. Dynamic 31P{1H} NMR spectroscopic and P4) agrees well with the experimental data for the fol-
1212
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218

(Phosphido)platinum Complexes
FULL PAPER
3
lowing parameters: δ(P2) ϭ 16.3, δ(P4) ϭ 15.8, J(P2-P4) ϭ findings indicate that both of the terminal phosphane li-
3
2
154, J(P2-P3) ϭ 16, J(P3-P4) ϭ 12 Hz (Table 2).
gands are trans to a bridging phosphide group. From the
Complex 3 is different from its Pd analogue 7 in that it 195Pt satellites the coupling constants [1J(Pt-P) ϭ 2070 Hz,
is not stable in solution and, with the rate depending on the 3J(Pt-P) ϭ 124 Hz (phosphorus signal at δ ϭ 21.3), and
temperature, undergoes an intramolecular oxidative addi- 1J(Pt-P) ϭ 1760 Hz, J(Pt-P) ϭ 68 Hz (phosphorus signal
3
tion of a PϪH bond with the rupture of the PtϪPt bond at δ ϭ 12.5)] could be extracted.
affording the new hydrido phosphido dinuclear platinum(II)
The signals of the bridging phosphide groups at δ ϭ
complex trans-[(PHCy2)(Cl)Pt(µ-PCy2)2Pt(PHCy2)(H)] (4).
Ϫ126.9 and δ ϭ Ϫ156.2 are both doublets of doublets due
to the mutual coupling [2J(P-P) ϭ 146 Hz] and also to the
additional coupling of each of them with the trans-phos-
phane ligand. 2D COSY 31P{1H} NMR spectroscopic ex-
periments enable one to clearly distinguish the satellites due
to different couplings with Pt1 and Pt2 (such satellites, six-
teen lines in total, are not unambiguously assigned in the
monodimensional 31P NMR spectrum) and the following
values for the relevant coupling constants can be extracted:
1
1
1J(P1-Pt1) ϭ 2497, J(P1-Pt2) ϭ 2239, J(P2-Pt1) ϭ 1729,
This complex shows one band at 281 cmϪ1 in the IR
spectrum that is due to the PtϪCl stretching, one broad
band at 2301 cmϪ1 attributable to the PϪH stretching, and
one intense band at 1929 cmϪ1 due to the PtϪH stretching.
The 31P{1H} NMR spectrum of 4 consists of four signals,
all flanked by 195Pt satellites, centred at δ ϭ 21.3, δ ϭ 12.5,
δ ϭ Ϫ126.9 and δ ϭ Ϫ156.2 (Table 3). The high-field sig-
nals at δ ϭ Ϫ126.9 and δ ϭ Ϫ156.21 indicate for 4, as in
the case of 2, a dinuclear structure in which two phosphide
groups are bound to two platinum atoms without PtϪPt
linkage.
1J(P3-Pt1) ϭ 1766, 1J(P3-Pt2) ϭ 1332, 1J(P4-Pt2) ϭ 2070 Hz.
1
The H NMR spectrum shows, beside resonances due to
aliphatic protons, two doublets centred at δ ϭ 4.79 and δ ϭ
4.35 as well as a doublet of doublets of doublets centred at
δ ϭ Ϫ3.19 [J(H-P) ϭ 138, 24, and 9 Hz]. The latter signal,
which is flanked by 195Pt satellites [1J(Pt-H) ϭ 912 Hz] is
due to a terminal hydride ligand cis to P4 (see Table 3 for P,
H, and Pt numbering for 4). Among the coupling constants
shown by the hydride signal the largest one [2J(H-P) ϭ
138 Hz] is attributed to the coupling with trans-P3, whereas
the two smaller ones [2J(H-P) ϭ 24 and 9 Hz] are due to
the couplings with cis-P4 and cis-P1, respectively.
When the Na reduction of 1 was carried out at room
temperature (instead of at 0 °C), the reaction solution
showed signals attributed to [Pt(µ-PCy2)(PHCy2)]2(PtϪPt)
(5) and [trans-Pt(PHCy2)2(PCy2)Cl] (6) in the 31P{1H}
NMR spectrum. 31P{1H} NMR of 5 consists of two triplets
centred at δ ϭ 242.0 and δ ϭ 19.6 [2J(P-P) ϭ 51 Hz] both
with 195Pt satellites.
Table 3. NMR parameters for complex 4 ([D6]benzene, 295 K);
chemical shifts (bold) are in ppm; coupling constants (normal) are
in Hz
The signal at δ ϭ 242.0 (Figure 3) which is flanked by
two sets of satellites due to the isotopomers containing one
or both NMR-active platinum atoms, does not change sub-
stantially in the proton-coupled spectrum, and belongs to
the bridging phosphide groups that couple with the Pt nuc-
lei [1J(Pt-P) ϭ 2598 Hz]. The low-field resonance of this
bridging phosphide group indicates the presence of a three-
membered Pt2P ring[7a,7b] and, therefore, of a PtϪPt bond
in complex 5. The triplet at δ ϭ 19.6 can be attributed to
the terminal dicyclohexylphosphane ligands. The signal
splits into a doublet of badly resolved triplets in the proton-
coupled spectrum [1J(P-H) ϭ 318 Hz] and is flanked by sat-
P1
P2
P3
P4
H1
9
P1
P2
P3
P4
H1
؊126.9
12
146
328
9
12
12.5
318
146
318
328
[a]
؊156.2
138
24
Ϫ3.19
[a]
21.3
24
138
[a] 2J(P3ϪP4) not assessed because less than signal linewidth.
Moreover, proton-coupled 31P NMR spectra show that, ellites due to 195Pt couplings [1J(Pt-P) ϭ 4811 Hz]. Neg-
of the two phosphide groups, the phosphorus atom at δ ϭ lecting signals due to the isotopomer containing two 195Pt
Ϫ156.2 is strongly hydrogen-coupled [2J(P-H) ϭ 138 Hz]. atoms, the main satellites each appear as a doublet of trip-
The signals at δ ϭ 21.3 and δ ϭ 12.5 belong to two in- lets due to the coupling with the phosphide groups [2J(P-
equivalent terminally bound secondary phosphane ligands P) ϭ 51 Hz] and with the other terminal phosphane ligand
[1J(P-H) ϭ 320 and 314 Hz, respectively] with the first ap- [3J(P-P) ϭ 70 Hz]. The relevant coupling constants found
pearing as a doublet [2J(P-P) ϭ 328 Hz], and the second as for the related complex [Pt{µ-P(SiMe3)2}(PEt3)]2(PtϪPt)
1
a doublet of doublets [2J(P-P) ϭ 318 and 12 Hz]. These are: J(Pt-P) ϭ 4957, 2J(P-P) ϭ 63, and 3J(P-P) ϭ 66 Hz.[9]
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218
1213

P. Mastrorilli, C. F. Nobile, F. P. Fanizzi, M. Latronico, C. Hu, U. Englert
proton-coupled spectrum, is flanked by satellites from
FULL PAPER
1
which a coupling constant J(P-Pt) ϭ 931 Hz could be ex-
tracted. Therefore such a triplet can be ascribed to a ter-
minal dicyclohexylphosphide group, coupled with two
equivalent phosphorus atoms, directly bound to the plat-
inum atom.
The doublet at δ ϭ 27.6 is flanked by two satellites char-
1
acterised by J(P-Pt) ϭ 3006 Hz. The pattern of the central
signal (isotopomer without 195Pt) in the proton-coupled
spectrum is typical for the A part of a second-order spin
[10]
system (AXY2)2
which is further coupled with a phos-
phorus atom [2J(P-P) ϭ 41 Hz]. In the present case A is 31P,
X is the proton bound to 31P, and Y are the methyne pro-
tons of the cyclohexyl rings. In Figure 5 the experimental
and simulated A part of the spectrum are reported. The
spectroscopic features obtained through the analysis de-
veloped by Palmer and Whitcomb[10] are collected in
Table 4. A similar pattern has been observed for the phos-
phorus atom of the coordinated secondary phosphane li-
gands in the palladium complexes [trans-Pd(SPh)2-
(PCy2H)2][11] and [trans-PdCl(CHCl2)(PtBu2H)2].[12]
Figure 3. Phosphide region of the 31P{1H} NMR spectrum for 5
([D6]benzene, 81 MHz, 295 K)
1
The H NMR spectrum of 5 shows the resonance of the
hydrogen atoms directly bound to phosphorus atoms for
the coordinated PCy2H at low field. This resonance appears
3
as a doublet of triplets [1J(P-H) ϭ 318 Hz and J(µP-H) ϭ
13 Hz] each broadened at the base due to HϪPt coupling
(Figure 4). Moreover, each of the triplet components ap-
pears split into three peaks, due to the additional coupling
with the cyclohexyl methyne protons, but the value of such
coupling constants (Ͻ 4 Hz) could not exactly be assessed.
Figure 4. 1H NMR spectrum in the low-field region for 5 ([D6]ben-
zene, 500 MHz, 295 K)
Figure 5. Proton-coupled 31P NMR spectrum of complex 6 in the
P1 region ([D6]benzene, 121 MHz, 295 K): (a) simulated, (b) experi-
mental; the asterisked triplet belongs to P2 satellites
The IR spectrum of 5 shows a strong band at 2238 cmϪ1
attributed to the PϪH stretching of the coordinated di-
cyclohexylphosphane ligand. Spectroscopically pure 5 was
directly obtained in an NMR tube by treating 3 in [D6]ben-
zene with sodium at room temperature.
The IR spectrum of 6 shows a strong band at 2324 cmϪ1
attributed to the PϪH stretching of the coordinated di-
cyclohexylphosphane ligands and a medium 259 cmϪ1 band
attributed to the PtϪCl stretching. According to the above
reported spectroscopic data, 6 can be formulated as [trans-
Pt(PHCy2)2(PCy2)Cl], a neutral terminal phosphido com-
plex of platinum(II).
Due to the exceedingly high trans-effect of phosphido
ligands, terminal (phosphido)platinum(II) complexes are
quite rare, so that the pioneering work of Chatt and David-
son concluded that, at least in the case of diphenylphos-
In the 31P{1H} NMR spectrum, complex 6 shows a phide, it seemed unlikely that such a ligand, terminally
doublet at δ ϭ 27.6 and a triplet at δ ϭ 20.6, in a 2:1 ratio bound to platinum(II), could even exist.[13] Nevertheless,
(as assessed by the integrals in the proton coupled spec- starting from the late 1980s, a number of terminal phos-
trum) with the same coupling constant of 41 Hz. The triplet phido complexes of platinum(II) have been prepared. The
at δ ϭ 20.6, which does not substantially change in the first molecule of this type to be synthesised was the dichloro-
1214
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218

(Phosphido)platinum Complexes
FULL PAPER
Table 4. Spectroscopic features for complexes 5 and 6 ([D6]benzene,
295 K); chemical shifts are in ppm; coupling constants are in Hz
Figure 6. Displacement ellipsoid plot[29] of 6; ellipsoids are scaled
to 30% probability, H atoms are shown with arbitrary radii
˚
Table 5. Selected bond lengths [A] and angles [°] for 6
PtϪP(3)
PtϪP(1)
2.272(3)
2.293(3)
PtϪP(2)
PtϪCl
2.326(3)
2.421(3)
[a]
|2J(P1-Pt)| ϭ 50 Hz. [b] 3J(P3-H1) ϭ 1 Hz.
P(3)ϪPtϪP(1)
P(3)ϪPtϪP(2)
P(1)ϪPtϪP(2)
P(3)ϪPtϪCl(1)
172.46(12)
99.87(11)
85.63(11)
86.03(11)
89.01(11)
171.98(12)
phosphide complex [PtCl(PEt3)(PCl2)].[14] Other examples
are the cations [Pt{PPh(CH2CH2PPh2)2}(PR2)]ϩ (R ϭ Cy, P(1)ϪPtϪCl(1)
Ph)[15] and [(xp3)Pt(PEt2)]ϩ [xp3 ϭ N(CH2CH2PPh2)3,
P(2)ϪPtϪCl(1)
P(CH2CH2PPh2)3][16] and the neutral [Pt(NCN)PPh2)]
[NCN ϭ C6H3(CH2NMe2)2-2,6] complex.[17] More recently,
Glueck et al. have described a series of terminal (phosphi- sions between the six cyclohexyl groups around the Pt
do)platinum(II) complexes of the type [Pt(dppe)Me(X)]nϩ atom. The relatively long[20] PtϪCl bond [2.421(3) A] indic-
˚
(X ϭ primary or secondary phosphide, n ϭ 0 or 1).[18]
ates a pronounced trans effect of the terminal phosphide
˚
In all of these terminal (phosphido)platinum complexes, group. The P(2)ϪPt bond length [2.326(3) A] is slightly
the chemical shifts of the phosphido phosphorus atom fall shorter than those reported for related terminal phosphido
in the range δ ϭ Ϫ88.4 to δ ϭ 56.7 and give scarce informa- platinum(II) complexes. The PtϪP(phosphido) bond
tion about the character of the phosphorus ligand. On the lengths of Pt(dppe)(Me)(PHMes*),[18b] Pt(dppe)(Me)(P-
1
other hand, the relatively small J(Pt-P) coupling constant Mes2),[18b] and Pt(S,S-Chiraphos)(Me)(PPhIs)[18d] [Mes* ϭ
expected between platinum and a terminal phosphido li- 2,4,6-(tBu)3C6H2, Mes ϭ 2,4,6-Me3C6H2, Chiraphos ϭ 2,3-
gand, rationalised in terms of low s character of the PtϪP bis(diphenylphosphanyl)butane, Is ϭ 2,4,6-(iPr)3C6H2] are,
bond,[18b] can be taken as diagnostic of the presence of such in fact, 2.378(5), 2.351(2), and 2.3622(15) A, respectively.
˚
1
a ligand. The value of the relevant JPt,P for the aforemen-
A possible pathway for the reaction of 1 with sodium at
tioned complexes ranges from 767 Hz to 1305 Hz. The room temp. could start with the abstraction of two sub-
1J(Pt-P) ϭ 931 Hz found for 6 supports our assignment as sequent chloride ions giving the dicoordinated Pt0 complex
[trans-Pt(PCy2H)2(PCy2)Cl].[19]
[Pt(PHCy2)2] (Scheme 2). This intermediate could lead to
In order to gain insight into the structure of complex intramolecular electrophilic attack of one coordinated
6, a crystallographic analysis was undertaken. The X-ray PHCy2 yielding [Pt(H)(PCy2)(PHCy2)] which, in turn, can
diffraction study revealed that 6 crystallises in the space dimerise to 5 via reductive elimination of hydrogen.[21]
¯
group P1 and contains a distorted square-planar plat-
On the other hand, at room temperature, 1 could also
inum(II) centre (Figure 6 and Table 5), the largest angle be- react with sodium dicyclohexylphosphide (one of the prod-
tween ligands being 99.87(11)° [P(3)ϪPtϪP(2)]. A tetrahed- ucts formed when 1 decomposes in the presence of sodium
ral distortion from planarity is also evident from the metal) giving 6 by substitution of the chloride ion with the
172.46(12)° [P(3)ϪPtϪP(1) and 171.98(12)° [P(2)ϪPtϪCl] dicyclohexylphosphide group (Scheme 2). A confirmation
angles, significantly differing from the ideal 180°.
of this proposed mechanism came from the reaction be-
The phosphide P atom is pyramidal as indicated by the tween 1 and LiPCy2 which gave pure 6.[22]
sum of the angles at P(2) of 320.5° (compared to 328.5° for
The lack of formation of both 5 and 6 when the reaction
a tetrahedral and 360° for a planar atom). The hydrogen of 1 with sodium metal is carried out at 0 °C can be ex-
atoms bonded to the phosphorus atom were located in a plained by admitting that both chloride ion abstraction and
Fourier difference synthesis. The two PϪH bonds of the intramolecular attack of a dicyclohexylphosphane ligand in
dicyclohexylphosphane ligands are both oriented toward [Pt(PHCy2)2] leading to [Pt(H)(PCy2)(PHCy2)] (Step a in
the phosphido ligand; such orientation minimises the repul- Scheme 2) are temperature-sensitive and slow in the reac-
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218
1215

P. Mastrorilli, C. F. Nobile, F. P. Fanizzi, M. Latronico, C. Hu, U. Englert
FULL PAPER
matic deuterated solvents were carefully dehydrated (Na) and de-
oxygenated (freeze and pump). Dicyclohexylphosphane was pur-
chased from Strem and used as received. PCy2Li[23] and
[24]
PtCl2(PhCN)2
were prepared by literature methods. Infrared
spectra were recorded with a Bruker Vector 22 spectrometer. Ele-
mental analyses (C, H) were carried out using a Carlo Erba model
EA 1108 instrument. The Cl and P contents (where reported) were
determined by potentiometric titration with AgCl (716DMS Me-
trohm) and by spectrophotometric methods (Uvikon 942 Kontron,
λ ϭ 460 nm), respectively. NMR spectra were recorded with
BRUKER Avance DRX500 (CARSO), BRUKER Avance
DPX300, and VARIAN XL200 spectrometers; frequencies are ref-
erenced to Me4Si (1H and 13C), 85% H3PO4 (31P), and H2PtCl6
(
195Pt).
cis-Dichlorobis(dicyclohexylphosphane)platinum(II) (1):[25]1.45 g of
dicyclohexylphosphane, dissolved in 10 mL of toluene, was added
dropwise to a toluene solution of trans-PtCl2(PhCN)2 (1.7 g in 30
mL) kept at 60 °C. After 1.5 h, the resulting white suspension was
cooled at room temp. and the solid filtered off, washed with toluene
(5 mL), and dried under vacuum affording pure 1 as a colourless
microcrystalline powder (2.03 g, 85% yield). IR (nujol mull): ν˜max ϭ
2351 w (PϪH), 285 m (PtϪCl) cmϪ1. 1H NMR (CDCl3, 500 MHz):
Scheme 2. Proposed mechanism for the sodium reduction of 1 at
room temperature
tion at 0 °C. Under these conditions both intermediate
[PtCl(PHCy2)2] and [Pt(PHCy2)2] could accumulate in the
reaction medium (Scheme 3). Therefore [Pt(PHCy2)2] may
become the preferential target for the attack of
[Pt(H)(PCy2)(PHCy2)] which results in the formation of 2
(effectively found in the reaction solution at 0 °C as the
major product). On the other hand, dimerization of
[PtCl(PHCy2)2] by HCl evolution (revealed as H2 and NaCl
formation in the presence of Na) could also account for the
formation of compound 3 as the minor product.
1
2
2
δ ϭ 3.60 [m, J(P-H) ϭ 362, J(Pt-H) ϭ 96, J(HP-CH) ϭ 6 Hz,
1
PH]. 31P NMR (CDCl3, 202 MHz): δ ϭ 18.6 [s, J(P-Pt) ϭ 3402,
2
3
1J(P-H) ϭ 362, J(P-PЈ) ϭ 19, J(P-HЈ) ϭ 8 Hz]. 195Pt{1H} NMR
(CDCl3, 64 MHz):
δ ϭ ϭ 3402 Hz].
Ϫ4540 [t, 1J(P-Pt)
C24H46Cl2P2Pt (662.58): calcd. C 43.51, H 7.00, Cl 10.70, P 9.35;
found C 43.48, H 7.10, Cl 10.75, P 9.27.
Reduction of 1 with Sodium at 0 °C: A suspension of cis-
PtCl2(PHCy2)2 (1) (0.98 g, 1.48 mmol) and sodium metal (0.067 g,
2.91 mmol) in toluene (40 mL) was vigorously stirred at 0 °C (ice
bath) for 9 h. In the course of the reaction dihydrogen evolved, as
revealed by gas chromatographic analysis. The resulting suspension
was filtered (to remove 0.243 g of unchanged 1 and 0.104 g of plat-
inum metal) and the solvent was removed at low temperature (0
°C). Treatment of the obtained solid with cold methanol afforded
pure 2 (0.12 g, 13.7% yield) as a white powder and a yellow solution
from which, after solvent removal and crystallisation of the residue
from THF/n-hexane (1:1) at Ϫ30 °C, pure 3 precipitated as a yellow
solid (28 mg, 3.1% yield). 1H NMR spectroscopic features of 2
other than those reported in Table 1 ([D8]toluene, 295 K): δ ϭ 4.50
[br. d, 1J(P-H) ϭ 317 Hz, H-P2). IR (nujol mull): ν˜max ϭ 2299 w
(PϪH), 1940 s (PtϪH) cmϪ1. C48H92P4Pt2 (1183.34): C 48.72, H
1
7.84, P 10.47; found C 47.86, H 7.95, P 10.13. H NMR spectro-
scopic features of 3 other than those reported in Table 2 ([D8]tol-
1
uene, 295 K): δ ϭ 4.31 [d, J(P-H) ϭ 319 Hz, H-P4], δ ϭ 4.45 [d,
1
1J(P-H) ϭ 312 Hz, H-P2], δ ϭ 5.3 [br. d J(P-H) ϭ 320 Hz, H-P3].
IR (nujol mull): ν˜max ϭ 2295 w and 2255 w (PϪH), 301 w (PtϪCl)
cmϪ1. C48H91ClP4Pt2 (1217.78): calcd. C 47.34, H 7.53, Cl 2.91;
found C 46.87, H 7.27, Cl 2.85.
Isomerisation of 3 To Give 4: A toluene solution of 3 was stirred at
50 °C for 5 h causing the colour to lighten from yellow-orange to
pale yellow. Evaporation of the solvent afforded a solid, which was
washed with cold methanol and after crystallisation from toluene/
n-hexane (2:1), 4 was obtained as white needles. IR (nujol mull):
Scheme 3. Proposed mechanism for the sodium reduction of 1 at
0 °C
1
ν˜max ϭ 2301 w (PϪH), 1929 w (PtϪH), 281 w (PtϪCl) cmϪ1. H
NMR spectroscopic features of 4 other than those reported in
Table 3 ([D6]benzene, 295 K): δ ϭ 4.35 [d, 1J(P-H) ϭ 314, 2J(Pt-
H) ϭ 98 Hz, H-P2], δ ϭ 4.79 [d, 1J(P-H) ϭ 320 Hz, H-P4].
C48H91ClP4Pt2 (1217.78): calcd. C 47.34, H 7.53, Cl 2.91, P 10.17;
found C 46.38, H 7.68, Cl 2.85, P 10.12.
Experimental Section
General Remarks: All manipulations were carried out under pure
dinitrogen, using freshly distilled and oxygen-free solvents. All aro-
1216
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218

(Phosphido)platinum Complexes
FULL PAPER
Reduction of 1 with Sodium at Room Temperature: A suspension of
methods and refined on F2 with the SHELXTL[28] suite of pro-
cis-PtCl2(PHCy2)2 (0.30 g, 0.45 mmol) and sodium metal (0.10 g, grams.
4.3 mmol) in toluene (30 mL) was vigorously stirred at room tem-
perature (25 °C) for 70 min. In the course of the reaction dihydro-
gen was evolved, as revealed by gas chromatographic analysis. The
Acknowledgments
resulting suspension was filtered and the solvent was removed in
vacuo from the yellow-orange filtrate. The residue was redissolved
in deuterated benzene and used for NMR spectroscopic analysis,
revealing the formation of 5 and 6 in an approximately 1:3 ratio.
We thank Dr. R. Giannandrea and Dr. M. Palma for invaluable
help. Mr. E. Pannacciulli is gratefully acknowledged for technical
assistance. Italian CNR and MURST are gratefully acknowledged
for financial support.
Reduction of 3 with Sodium: A light yellow solution of complex 3
in [D6]benzene was treated with sodium sand in an NMR tube at
room temperature until the hydrogen evolution stopped (about
0.5 h). The resulting dark yellow solution was analysed by NMR
spectroscopy giving signals due to 5 alone.
[1]
M. Aresta, C. F. Nobile, A. Sacco, Inorg. Chim. Acta 1975,
12, 167Ϫ178.
[2]
P. Mastrorilli, G. Moro, C. F. Nobile, M. Latronico, Inorg.
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C. F. Nobile, G. Vasapollo, P. Giannoccaro, A. Sacco, Inorg.
[3]
Chim. Acta 1981, 48, 261Ϫ263.
trans-Chloro(dicyclohexylphosphido)bis(dicyclohexylphosphane)-
[4]
R. Giannandrea, P. Mastrorilli, M. Palma, C. F. Nobile, F. P.
platinum(II) [Pt(PHCy2)2(PCy2)Cl] (6):
A suspension of cis-
Fanizzi, U. Englert, Eur. J. Inorg. Chem. 2000, 2573Ϫ2576.
R. Giannandrea, P. Mastrorilli, C. F. Nobile, U. Englert, J.
[Pt(PHCy2)2Cl2] (0.54 g, 0.82 mmol) and PCy2Li (0.166 g,
0.82 mmol) in toluene (20 mL) was vigorously stirred at 0 °C until
a yellow solution was obtained (about 8 h). LiCl was filtered and
the solution concentrated in vacuo to ca. 5 mL. By cooling at Ϫ20
°C pale yellow crystals of 6 precipitated which were isolated by
filtration (0.435 g, 65%). IR (nujol mull): ν˜max ϭ 2324 s (PϪH),
259 m (PtϪCl) cmϪ1. C36H68ClP3Pt (824.40): calcd. C 52.45, H
8.31, Cl 4.30, P 11.27; found C 51.93, H 8.45, Cl 4.37, P 11.32.
[5]
Chem. Soc., Dalton Trans. 1997, 1355Ϫ1358.
[6]
K. R. Dixon, A. D. Rattray, Inorg. Chem. 1978, 17, 1099Ϫ1103.
[7] [7a]
[7b]
P. E. Garrou, Chem. Rev. 1981, 81, 229.
A. J. Carty, S.
A. Maclaughlin, D. Nucciarone, in: Phosphorus-31 NMR Spec-
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Quin), VCH, New York, 1987, p. 559. Examples of Pt2P three-
membered rings can be found in: [7c]P. Leoni, S. Manetti, M.
Pasquali, Inorg. Chem. 1995, 34, 749Ϫ752. [7d] P. Leoni, G. Chi-
aradonna, M. Pasquali, F. Marchetti, Inorg. Chem. 1999, 38,
X-ray Data Collection, Structure Solution, and Refinement of 6:[26]
Crystal data and parameters for intensity data collection and struc-
ture refinement are compiled in Table 6. A pale yellow rod with the
approximate dimensions of 0.15 ϫ 0.11 ϫ 0.03 mm was studied at
room temperature with a BRUKER-AXS SMART Apex diffracto-
meter. An empirical absorption correction[27] was applied (max.
trans. 1.000, min. trans. 0.797). The structure was solved by direct
[7e]
253Ϫ259.
J. Jans, R. Naegeli, L. M. Venanzi, A. Albinati,
J. Organomet. Chem. 1983, 247, C37ϪC41. [7f] P. W. N. M. van
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[7g]
ganometallics 1990, 9, 1211Ϫ1222.
P. Leoni, M. Pasquali,
V. Cittadini, A. Fortunelli, M. Selmi, Inorg. Chem. 1999, 38,
5257Ϫ5265. [7h] P. Leoni, S. Manetti, M. Pasquali, A. Albinati,
[7i]
Inorg. Chem. 1996, 35, 6045Ϫ6052.
R. Bender, P.
Braunstein, A. Dedieu, P. D. Ellis, B. Huggins, P. D. Harvey,
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[7j] P. Leoni, M. Pasquali, A. Fortunelli, G. Germano, A. Albin-
ati, J. Am. Chem. Soc. 1998, 120, 9564Ϫ9573. [7k] S. Cristofani,
Table 6. Crystal data and structure refinement for 6
P. Leoni, M. Pasquali, F. Eisentraeger, A. Albinati, Organomet-
[7l]
´
L. R. Falvello, J. Fornies, C.
allics 2000, 19, 4589Ϫ4595.
[7m]
Empirical formula
Formula mass
C36H68ClP3Pt
824.35
293(2)
`
Fortun˜o, F. Martınez, Inorg. Chem. 1994, 33, 6242Ϫ6246.
R. Bender, P. Braunstein, A. Tiripicchio, M. Tiripicchio
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H. Wachtler, W. Schuh, K. H. Ongania, K. Wurst, P. Peringer,
[7n]
Temperature [K]
˚
Wavelength [A]
0.71073
triclinic
[7o]
Crystal system
Space group
Organometallics 1998, 17, 5640Ϫ5646.
A. R. Siedle, R. A.
¯
P1 (no. 2)
Newmark, W. B. Gleason, J. Am. Chem. Soc. 1986, 108,
[7p]
Unit cell dimensions
767Ϫ773.
N. Hadj-Bagheri, J. Browning, K. Dehghan, K.
˚
a [A]
9.9460(10)
10.7743(11)
18.772(2)
R. Dixon, N. J. Meanwell, R. Vefghi, J. Organomet. Chem.
˚
1990, 396, C47ϪC52. [7q] L. R. Falvello, J. Fornies, C. Fortun˜o,
b [A]
´
˚
c [A]
`
`
A. Martın, A. P. Martınez-Sarin˜ena, Organometallics 1997, 16,
[7r]
α [°]
β [°]
γ [°]
80.872(2)
79.098(2)
82.054(3)
1938.1(3)
5849Ϫ5856.
A. L. Bandini, G. Banditelli, G. Minghetti, J.
[7s]
Organomet. Chem. 2000, 595, 224Ϫ231.
E. Alonso, J. For-
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2001, 20, 850Ϫ859.
´
`
3
˚
V [A ]
[8]
Z
2
For temperature dependence of relaxation time see: F. A.
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H. Schaefer, D. Binder, Z. Anorg. Allg. Chem. 1988, 560,
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R. A. Palmer, D. R. Whitcomb, J. Magn. Res. 1980, 39,
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M. Pasquali, F. Marchetti, P. Leoni, T. Beringhelli, G. D’Al-
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phorus Sulfur 1987, 30, 143.
Dcalcd. [Mg mϪ3
]
1.413
3.835
1.12Ϫ28.26
9509
Absorption coeff. [mmϪ1
θ range for data coll. [°]
Independent reflections
Observed reflections
Refinement method
Data/parameters
]
[9]
[10]
[11]
3665
full-matrix least squares on F2
9509/370
0.840
0.0747
0.1279
Goodness-of-fit on F2
Final R[a] [I Ͼ 2σ(I)][a]
wR2[b] (all data)
[12]
[13]
[14]
Ϫ3
˚
Largest diff. peak/hole [eA
]
1.657, Ϫ0.881 (close to Pt)
[a]
[b]
R ϭ Σ||Fo| Ϫ |Fc||/Σ|Fo|. Rw ϭ [Σw(|Fo| Ϫ |Fc|)2/Σw|Fo|2]1/2
.
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218
1217

P. Mastrorilli, C. F. Nobile, F. P. Fanizzi, M. Latronico, C. Hu, U. Englert
FULL PAPER
[15]
[21]
A. Handler, P. Peringer, E. P. Muller, J. Chem. Soc., Dalton
Trans. 1990, 3725.
A symilar mechanism has been suggested for the related Ni
and Pd complexes [Ni(PHCy2)(µ-PCy2)]2 (see ref.[5]
and
)
[16]
[17]
F. Cecconi, C. A. Ghilardi, S. Midollini, S. Moneti, A. Orland-
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F. Maassarani, M. F. Davidson, I. C. M. Wehman-Ooyevaar,
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van Koten, Inorg. Chim. Acta 1995, 235, 327Ϫ338.
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263Ϫ270).
[22]
Such a type of reaction is unprecedented for Pt species, except
in the case of (Et3P)2PtCl2 with LiP(SiMe3)2 reported in ref.[9]
where unstable compounds such as (Et3P)2Pt[P(SiMe3)2]Cl and
(Et3P)2Pt[P(SiMe3)2]2 form, the latter of which, in turn, affords,
by splitting off of the phosphane ligands, a mixture of a (di-
phosphene)Pt0 complex and a phosphido-bridged PtI complex.
K. Issleib, W. Tschach, Chem. Ber. 1959, 92, 1118Ϫ1126.
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[18] [18a]
D. K. Wicht, I. V. Kourkine, B. M. Lew, J. M. Nthenge,
[18b]
D. S. Glueck, J. Am. Chem. Soc. 1997, 119, 5039Ϫ5040.
D. K. Wicht, S. N. Paisner, B. M. Lew, D. S. Glueck, G. P. A.
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[18c]
[23]
[24]
[25]
Nolan, Organometallics 1998, 17, 652Ϫ660.
D. K. Wicht,
D. S. Glueck, L. M. Liable-Sands, A. L. Rheingold, Organo-
[18d]
metallics 1999, 18, 5130Ϫ5140.
D. K. Wicht, I. Kovacik,
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[26]
CCDC-172800 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
at www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cam-
bridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, UK [Fax: (internat.) ϩ 44-1223/336-033;
E-mail: deposit@ccdc.cam.ac.uk].
[19]
In this regard it should be noted that the related complex trans-
Pt(PEt3)(PPhH)Cl proposed as intermediate in the reaction be-
tween (PPh)5 and PtCl2(PEt3)2 on the basis of its spectroscopic
features (I. P. Parkin, A. M. Z. Slawin, D. J. Williams, D. Wool-
lins, Inorg. Chim. Acta 1990, 172, 159Ϫ163) exhibits a coupling
1
constant J(P-Pt) of 3460 Hz which seems to be very unusual
[27] ]G. M. Sheldrick, SADABS, University of Göttingen, Ger-
many, 1996.
for a terminal phosphide group.
[20]
A. G. Orpen, L. Brammer, F. H. Allen, O. Kennard, D. G.
Watson, R. Taylor, Typical interatomic distances: organometal-
lic compounds and coordination complexes of the d- and f-block
metals, International Tables for Crystallography, vol. C (Ed.: A.
J. C. Wilson), Kluwer Academic Publishers, Dordrecht, The
Netherlands, 1995, pp. 707Ϫ791.
[28] ]G. M. Sheldrick, SHELXTL, Version 5.1. Bruker AXS Inc.,
Madison, Wisconsin, USA, 1998.
[29]
A. L. Spek, PLATON-94, University of Utrecht, The
Netherlands, 1994.
Received October 30, 2001
[I01424]
1218
Eur. J. Inorg. Chem. 2002, 1210Ϫ1218