Reaction of triangulo-clusters (see abstract)

Article abstract of DOI:10.1039/b203075f

Hexafluoro-2-butyne, CF₃C≡CCF₃, reacts with the triangulo-clusters [Pt₃(μ-CO)₃(PR₃)₃] to give the diplatinum(o) compounds [Pt₂(CO)₂(PR₃)₂ (μ-η²:η² -CF₃ C≡CCF₃)] {PR₃ = PPh₃ (1), PBzPh₂ (2), PCy₃ (3), PⁱPr₃ (4)}. Spectroscopic properties are reported which are in accord with the molecular structures for 1 and 3, both having the acetylenic C-C axis perpendicular to the Pt-Pt axis, bridging two [Pt(CO)(PR₃)] fragments in a μ-η²:η² fashion. A large excess of hexafluorobutyne slowly converts 1 and 2 to the diplatinum(II) complexes [Pt₂(CO)₂(PR₃)₂ (μ-η¹:η¹-CF₃C≡CCF₃) ₂] {PR₃ = PPh₃ (5), PBzPh₂ (6)}, having two planar hexafluorobutyne bridges. This stereochemistry has been established by NMR and IR spectra, and confirmed by single-crystal X-ray diffraction.

Full text of DOI:10.1039/b203075f

View Article Online / Journal Homepage / Table of Contents for this issue
Reaction of triangulo-clusters [Pt3(ꢀ-CO)3(PR3)3] with
hexafluorobutyne. The X-ray crystal structures of
2
2
᎐
[Pt (CO) (PR ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF )] (PR ؍ PPh or PCy )
᎐
2
2
3 2
3
1
3
3
3
3
1
᎐
and [Pt (CO) (PBzPh )(ꢀ-ꢁ :ꢁ -CF C᎐CCF ) ]
᎐
2
2
2
3
3 2
Renzo Ros,*a Augusto Tassan,a Raymond Roulet,*b Gàbor Laurenczy,b Virginie Duprezb and
Kurt Schenkc
a Dipartimento di Processi Chimici dell’Ingegneria, Via Marzolo 9, I-35131 Padova, Italy
b Ecole Polytechnique Fédérale de Lausanne, BCH, CH-1015 Lausanne, Switzerland
c Institut de Cristallographie de l’Université de Lausanne, BSP, CH-1015 Lausanne, Switzerland
Received 27th March 2002, Accepted 12th July 2002
First published as an Advance Article on the web 20th August 2002
᎐
Hexafluoro-2-butyne, CF C᎐CCF , reacts with the triangulo-clusters [Pt (µ-CO) (PR ) ] to give the diplatinum()
᎐
3
3
3
3
3 3
2
2
i
᎐
compounds [Pt (CO) (PR ) (µ-η :η -CF C᎐CCF )] {PR = PPh (1), PBzPh (2), PCy (3), P Pr (4)}. Spectroscopic
᎐
2
2
3
2
3
3
3
3
2
3
3
properties are reported which are in accord with the molecular structures for 1 and 3, both having the acetylenic C–C
axis perpendicular to the Pt–Pt axis, bridging two [Pt(CO)(PR3)] fragments in a µ-η2:η2 fashion. A large excess of
1
1
᎐
hexafluorobutyne slowly converts 1 and 2 to the diplatinum() complexes [Pt (CO) (PR ) (µ-η :η -CF C᎐CCF ) ]
᎐
2
2
3
2
3
3 2
{PR3 = PPh3 (5), PBzPh2 (6)}, having two planar hexafluorobutyne bridges. This stereochemistry has been established
by NMR and IR spectra, and confirmed by single-crystal X-ray diffraction.
is also reported, and is the first example of a diplatinum()
complex having two parallel alkyne bridges.
Introduction
The ability of hexafluorobutyne (hfb) to coordinate only one
metal centre is well known.1–3 Such complexes are schematically
represented as I and designated as η2-acetylene derivatives. Less
Results and discussion
common are species in which hfb is bonded to two metal centres
1
1
4
᎐
in a parallel mode (II), as in [Pt (µ-η :η -CF C᎐CCF )(cod) ],
Hexafluorobutyne reacts at room temperature with [Pt3(µ-CO)3-
(PR3)3] in dichloromethane to give the diplatinum() com-
᎐
2
3
3
2
or in the perpendicular mode (III), as in [Pt2(µ-η2:η2-CF3-
2
2
2
2
᎐
᎐
C᎐CCF )(cod) ] or in the structurally analogous [Pt (µ-η :η -
pounds [Pt (CO) (PR ) (µ-η :η -CF C᎐CCF )] {PR = PPh3
᎐
᎐
3
2
2
2 2 3 2 3 3 3
5
᎐
CF C᎐CCSiMe )(cod) ], formulated on the basis of spectro-
(1), PBzPh2 (2), PCy3 (3), PiPr3 (4)}. In these complexes, the
alkyne ligand acts as a 4-electron donor and thereby stabilizes
the two 16-electron platinum units, which are structurally
analogous to the di(tert-butyl)acetylenedicarboxylate derivative
᎐
3
3
2
scopic, analytical, and molecular weight data. The preparation
6
᎐
of [Pt (CO) (µ-CF C᎐CCF )(µ-dppm)] has been reported, but
᎐
2
2
3
3
its structure is not known.
2
2
t
t
᎐
The two alternative geometries II and III, together with their
interconversion energies, have been analysed using qualitative
molecular orbital theory.7
[Pt (CO) (PCy ) (µ-η :η - BuO CC᎐CCO Bu)] {PR = PCy3
᎐
2 2 3 2 2 2 3
(3), PiPr3 (4)}.10 This binding mode may be identified by its
spectroscopic signature. All the dinuclear complexes 1–4 are air
stable as solids and in solution (their IR and NMR spectra were
essentially invariant for a few days). The IR spectrum presents a
strong band in the 2012–2030 cmϪ1 region characteristic of
terminal CO ligands. All these complexes present only one
19F-NMR resonance, in agreement with the dimeric structure
of type III, where the CF3 groups occupy symmetrically equiva-
lent sites (Table 1). For example, the spectrum of 1 (Fig. 1)
exhibits five doublets of relative intensity 1:8:17:8:1. This
spectrum is the superimposition of the sub-spectra related to
the three isotopomers, namely a central doublet due to the
A3AЈ3MMЈ spin system (43.82% abundance, no 195Pt nuclei),
which is flanked by two doublets due to the A3AЈ3MMЈX spin
In the course of our continuing investigation8,9 into the
chemical reactivity of the triangulo-complexes [Pt3((µ-CO)3-
(PR3)3], they were found to react with hexafluorobutyne to give
the stable dinuclear derivatives [Pt2(CO)2(PR3)2(µ-η2:η2-CF3-
i
᎐
C᎐CCF )] {PR = PPh (1), PBzPh (2), PCy (3), P Pr (4)}, with
᎐
3
3
3
2
3
3
type III structures. Under a large excess of hfb, two of these
slowly convert to the diplatinium() complexes [Pt2(CO)2-
1
1
᎐
(PR ) (µ-η :η -CF C᎐CCF ) ] {PR = PPh (5), PBzPh (6)}.
᎐
3
2
3
3
2
3
3
2
The molecular structures of 1 and 3 have been established by
single-crystal X-ray diffraction, and compared with the struc-
2
2 t
᎐
turally similar complex [Pt (CO) (PCy ) (µ-η :η – BuO CC᎐
᎐
2
2
3
2
2
CCO2 Bu)] recently described.10 The molecular structure of 6
t
DOI: 10.1039/b203075f
J. Chem. Soc., Dalton Trans., 2002, 3565–3570
This journal is © The Royal Society of Chemistry 2002
3565

View Article Online
Table 1 Selected 19F-, 31P{1H}-, and 13C{1H}-NMRa data for com-
plexes 1–4 in CD2Cl2 at 25 ЊC (δ/ppm, J/Hz)
spectrum of the PBzPh2 derivative 2 has a very similar pattern
(Table 1). The steric bulk of phosphine ligands, such as PCy3 or
PiPr3 in 3 and 4, respectively, renders the two CF3 groups mag-
netically non-equivalent, resulting in two multiplets instead of
the expected two doublets relative to the isotopomer having one
195Pt (see crystal structures); i.e. the two CF3 groups have two
different coupling constants with the neighboring 195Pt atom,
5
together with a small but measurable J(F–F). In order to
assign these coupling constants, we have collected the 19F{31P}-
NMR spectra of compounds 3 and 4 with an adapted Bruker
DRX 400 spectrometer. All spectra were satisfactory simulated
using the following simplified spin systems: 19F{31P}, A3AЈ3
(43.82%, no 195Pt nuclei), A3AЈ3X (44.75%, one 195Pt nucleus),
and A3AЈ3XXЈ (11.42%, two 195Pt nuclei). As an example, the
observed and computed spectra of the dimeric cluster 4 are
illustrated in Fig. 2.
PR3
PPh3 (1)
PPh2Bz (2)
PCy3 (3)
PiPr3 (4)
a
δ(F)trans
Ϫ49.00
102.8
102.8
13.9
< 1
∼1.2
16.81
3351
Ϫ70
< 1
382
182.1
1658
∼4.1
∼ Ϫ19
< 0.7
Ϫ49.69
102.6
102.6
14.0
< 1
∼1.3
11.95
3356
Ϫ67
< 1
381
Ϫ48.68
97.4
117.7
14.3
< 1
3.4
28.87
3191
Ϫ63
< 1
331
183.1
1632
∼4.6
∼ Ϫ17
< 0.7
Ϫ48.00
97.3
115.9
14.1
< 1
3.1
42.90
3222
Ϫ69
< 1
341
183.7
1633
∼4.2
∼ Ϫ19
< 0.6
3J(F–Pt)trans
a
3J(F–Pt)cis
a
4J(F–P)trans
a
4J(F–P)cis
a
The 31P{1H} and 13C{1H}-NMR spectra of complexes 1–4
are also diagnostic of such a dinuclear geometry. All spectra are
consistent with a Pt2P2C2 system, where both phosphorous and
carbonyl atoms occupy symmetrically equivalent sites, showing
a single resonances for these nuclei, with similar patterns of
satellites. The rather low values of the 195Pt–195Pt-coupling con-
stant (331–382 Hz, observed in the 31P spectra)11–13 rule out any
direct metal–metal interaction. Satisfactory computer simu-
lations of these spectra have been achieved on the basis of such
a system; for example, the 13C{1H}-NMR spectral analysis
results in the superimposition of the spectra of each of the
isotopomers A3AЈ3MMЈNNЈ (43.82%, no 195Pt nuclei), A3AЈ3-
MMЈNNЈX (44.75%, one 195Pt nucleus, X), and A3AЈ3MMЈ-
NNЈXXЈ (11.42%, two 195Pt nuclei, X and XЈ). The NMR data
for all complexes are summarized in Table 1.
5J(F–F)
δ(P)
1J(P–Pt)
3J(P–Pt)
4J(P–P)
2J(Pt–Pt)
δ(C)b
182.9
1656
∼4.4
1J(C–Pt)
2J(C–P)
3J(C–Pt)
4J(C–F)trans
∼ Ϫ18
c
d
—
a Data for CF3 groups in pseudo-trans and pseudo-cis positions relative
to PR3. b 13C{1H}-NMR data for carbonyl ligands of the complexes
enriched (>99%) in 13CO. c Data for CO groups in pseudo-trans
positions relative to one CF3 group. d Not observed.
The reaction of hexaflurobutyne (hfb) with [Pt3(µ-CO)3-
(PCy3)3] (1:1 molar ratio) in toluene was monitored by NMR at
Ϫ50 ЊC. No evidence was found of an adduct [Pt3(µ-CO)3-
(PCy3)3(π-hfb)] similar to those observed with olefins. Dimer 3
was observed, together with an isomer of Cs symmetry
(obtained by interconverting the positions of P1 and C5 in
Fig. 4; δ(CO) 183.4 ppm, J(C–Pt) 1651 Hz, δ(P) 26.8 ppm,
J(P–Pt) 3085 Hz). Upon warming the solution to Ϫ20 ЊC, the
latter isomer slowly converts to 3. As one third of a mole of
starting trimer is reformed per mole of dimer formed, the final
solution shows a 3:[Pt3(CO)3(PCy3)3] molar ratio of 1:0.33.
When a large excess of hexafluorobutyne was introduced to a
dichloromethane solution of the starting clusters [Pt3(µ-CO)3-
(PR3)3] (or of the dinuclear intermediates 1 and 2), a slow
declusterization reaction occurred at room temperature. After
ca. 70 h, total conversion to the scarcely soluble complexes
1
1
᎐
[Pt (CO) (PR ) (µ-η :η -CF C᎐CCF ) ] {PR = PPh (5), PBz-
᎐
2
2
3
2
3
3
2
3
3
Ph2 (6)} was evident, on the basis of their CO frequencies at
2077 and 2078 cmϪ1 respectively, which are characteristic of
terminally bonded carbonyl ligands. Their dimeric nature was
ascertained by X-ray analysis of 6, and their formulation as
diplatinum() complexes is based on the observed square
planar arrangement of ligands and on a CO stretching shift
ca. 40 cmϪ1 to higher wavelengths relative to that observed for
the platinum() dimers 1 and 2.
The 19F-NMR spectra of 5 and 6 display two signals of equal
intensities which exclude any mirror plane containing the
Pt ؒ ؒ ؒ Pt axis or perpendicular to it. The lower field signal (F1b,
Fig. 1 Observed (top) and simulated (bottom) 19F-NMR spectra of
2
2
4
᎐
[Pt2(CO)2(PPh3)2(µ-η ,η -CF3C᎐CCF3)] (1) in CD2Cl2 at 25 ЊC.
F2a; Table 2) appears as a doublet of quartets due to J(F–P)
᎐
5
and J(F–F) coupling with 195Pt satellites, whereas the higher
system (44.75% abundance, one 195Pt nucleus, X), and two
external, less intense doublets for the A3AЈ3MMЈXXЈ spin
system (11.42% abundance, two 195Pt nuclei, X and XЈ), with
field signal (F1a, F2b) is a multiplet due to the additional 5J(F–P)
3
coupling; this assignment is consistent with a lower J(F–Pt)
according to the greater trans-influence of PR3 relative to CO.
The latter pair of CF3 groups is therefore non-equivalent to the
former due to its pseudo-trans position with respect to one
phosphorous atom. The spectra where simulated successfully
using the superposition of three spin systems, A3AЈ3MMЈ,
A3AЈ3MMЈX, and A3AЈ3MMЈXXЈ for the isotopomers with
zero, one, and two 195Pt nuclei, respectively. The values of the
4
4
3J(Pt–F) = 102.8, J(P–F)trans = 13.9, and J(P–F)cis ≤ 1 Hz. In
view of their magnitudes, the two P–F coupling are assigned to
couplings with the P atoms in pseudo-trans positions; pseudo-
cis P–F couplings could not be detected (< 1 Hz). This result
implies two “Pt(CO)(PPh3)” units symmetrically bridged to the
hexafluorobutyne ligand in a µ-η2:η2-fashion. The 19F-NMR
3566
J. Chem. Soc., Dalton Trans., 2002, 3565–3570

View Article Online
i
2
2
Fig. 2 (a) Observed (top) and simulated (bottom) 19F-NMR spectra of [Pt2(CO)2(P Pr3)2(µ-η ,η -CF3C᎐CCF3)] (4). (b) The corresponding 19F{31P}-
᎐
᎐
NMR spectra; N = 3J(F–Pt)cis ϩ 3J(F–Pt)trans
.
Fig. 3 ORTEP representation at the 40% probability level of one (1b)
of the two independent molecules of [Pt2(CO)2(PPh3)2(µ-η2:η2-
᎐
CF3C᎐CCF3)] (1).
᎐
Fig. 4 ORTEP representation at the 40% probability level of complex
2
2
᎐
[Pt2(CO)2(PCy3)2(µ-η :η -CF3C᎐CCF3)] (3).
᎐
coupling constants reported in Table 2 were confirmed by
selective 19F{31P} decoupling and selective homonuclear
decoupling.
the average value of 1.202(5) Å found in free acetylenes.17 Like-
wise, the mean values for the acetylenic bend-back angle are
significantly greater (47.4, 46.7, and 48.0Њ for 1a, 1b, and 3,
respectively) than the corresponding values for PtL2(CF3-
Crystal structures
᎐
C᎐CCF ) (39.9 and 45.4Њ for L = PPh and PCy , respectively),
᎐
3
3
3
In order to confirm the structures of both dimeric compound
types, single-crystal X-ray crystallographic analyses were com-
pleted on 1 and 3. Details are summarized in the Experimental
section. Two independent molecules are present in the crystals
of 1 (1a and 1b). Selected intramolecular bond lengths and
angles for the molecules are give in Table 3. Views of the mole-
cules 1b and 3 are presented in Fig. 3 and 4, respectively. The
atoms coordinated to platinum deviate slightly from planarity:
the values for the angle between the plane defined by C(2), C(1),
Pt(1) and Pt(1), P(1), C(5) are 1.3, 4.2, and 7.5Њ for 3, 1a, and
1b, respectively. The corresponding values for the planes at
Pt(2) are 2.9, 6.0, and 6.7Њ for 3, 1a, and 1b, respectively. The
hexafluorobutyne has been perturbed considerably on coordin-
ation. The acetylenic bond lengths of 1.417(6) (mean) and
1.401(4) Å for 1a, 1b, and 3, respectively are larger than the
values of 1.255(9), 1.260(10), and 1.282(9) Å observed in the
probably because the acetylenic carbon atoms are bonded to
two metal atoms. No correlation could be found between the
Pt–C–C–F dihedral angles and the coupling constants reported
in Table 1.
In order to confirm the dimeric nature of the products of the
reaction of the starting clusters with a large excess of hexa-
fluorobutyne, a single-crystal X-ray crystallographic analysis
1
1
᎐
was completed on [Pt (CO) (PBzPh ) (µ-η :η -CF C᎐CCF ) ]
᎐
2
2
2
2
3
3 2
(6). Details are summarized in the Experimental section.
Selected intramolecular bond lengths and angles for the
molecules are give in Table 3. The molecular structure of 6 is
illustrated in Fig. 5. As expected from the NMR data, two
molecular Pt(CO)(PBzPh2) fragments are present in the struc-
ture, both σ-bonded symmetrically by two hexafluorobutyne
ligands. The C(1a)–C(2a) and C(1b)–C(2b) separations of
1.316(5) and 1.303(5) Å, respectively, and the angles about
C(1a), C(2a), C(1b), and C(2b) suggest that the hybridization of
these atoms is close to sp2. The Pt()–C(sp2) distances in 6
14
᎐
zerovalent platinum compounds PtL (CF C᎐CCF ) L = PPh ,
᎐
2
3
3
3
PCy3,15 and AsPh3,16 respectively, and significantly larger than
J. Chem. Soc., Dalton Trans., 2002, 3565–3570
3567

View Article Online
Table 2 Selected NMR data for 5 and 6 in CD2Cl2 at 25 ЊC (δ/ppm, J/Hz)
F2a
F1b
P1
P2
Pt1
Pt2
Complex 5
δ(F1a, 2b
δ(F1b, 2a
δ(P1, 2)
)
)
Ϫ54.66
Ϫ52.53
8.87
F1a
F2b
F1b
F2a
P1
12.6
8.8
3.9
1.5
3.9
8.8
123.9
∼6
12.6
∼6
130.0
∼10
123.9
∼10
1.5
130.0
δ(CO5, 6)
174.8a
1949
P2
1949
Complex 6
δ(F1a, 2b
δ(F1b, 2a
δ(P1, 2)
)
)
Ϫ54.80
Ϫ51.56
12.77
F1a
F2b
F1b
F2a
P1
13.3
8.9
4.1
2.2
4.1
8.9
122.5
∼6
130.2
∼9
2001
∼6
13.3
122.5
∼9
2.2
130.2
δ(CO5,6)
173.5a
P2
2001
a 1J(CO5–Pt1) = 1J(CO6–Pt2) 1113, 1106; 2J(CO5–P1) = 2J(CO6–P2) ∼4.4, ∼3.9; 4J(CO5–F1b) = 4J(CO6–F2a) ∼3.2, ∼3.7 for 5 and 6, respectively.
Table 3 Selected bond lengths [Å] and angles [Њ] for 1, 3, and 6
1a
1b
3
6a
Pt(1)–Pt(2)
Pt(1)–P(1)
Pt(1)–C(5)
Pt(1)–C(1)
Pt(1)–C(2)
Pt(2)–P(2)
Pt(2)–C(6)
Pt(2)–C(1)
Pt(2)–C(2)
C(1)–C(2)
C(2)–C(3)
C(1)–C(4)
C(5)–O(5)
C(6)–O(6)
3.056(1)
2.304(1)
1.905(5)
2.069(4)
2.065(4)
2.311(1)
1.885(4)
2.056(3)
2.098(3)
1.416(6)
1.450(6)
1.479(6)
1.118(6)
1.125(5)
3.096(1)
2.315(1)
1.892(5)
2.063(4)
2.053(4)
2.307(1)
1.904(4)
2.059(4)
2.072(4)
1.418(5)
1.469(6)
1.474(5)
1.109(6)
1.096(5)
3.068(1)
2.337(1)
1.872(5)
2.068(3)
2.069(3)
2.329(1)
1.873(4)
2.063(3)
2.069(3)
1.401(4)
1.468(5)
1.471(5)
1.143(5)
1.140(4)
3.218(1)
2.339(1)
1.936(4)
(a) 2.086(3), (b) 2.092(3)
2.335(1)
1.917(4)
(a) 2.075(3), (b) 2.085(4)
(a) 1.316(5), (b) 1.303(5)
(a) 1.500(5), (b) 1.509(5)
(a) 1.487(5), (b) 1.495(5)
1.104(4)
1.126(5)
Pt(1)–C(1)–C(2)
Pt(1)–C(1)–Pt(2)
Pt(1)–C(1)–C(4)
Pt(2)–C(1)–C(4)
C(1)–C(2)–Pt(2)
Pt(1)–C(2)–Pt(2)
Pt(1)–C(2)–C(3)
Pt(2)–C(2)–C(3)
C(5)–Pt(1)–P(1)
C(1)–Pt(1)–C(2)
C(5)–Pt(1)–C(1)
P(1)–Pt(1)–C(2)
Pt(1)–C(5)–O(5)
C(6)–Pt(2)–P(2)
C(1)–Pt(2)–C(2)
C(6)–Pt(2)–C(2)
P(2)–Pt(2)–C(1)
Pt(2)–C(6)–O(6)
C(1)–C(2)–C(3)
C(2)–C(1)–C(4)
P(1)–Pt(1)–C(1)
P(2)–Pt(2)–C(2)
69.8(2)
95.6(2)
128.7(3)
132.8(3)
68.5(2)
69.5(2)
97.4(1)
129.1(3)
131.1(3)
69.4(2)
70.3(2)
95.9(1)
128.8(2)
133.3(3)
69.9(2)
95.7(1)
70.1(2)
128.2(3)
97.5(1)
39.6(1)
112.6(2)
110.3(1)
178.8(5)
97.5(1)
(a) 116.8(2), (b) 117.6(3)
(a) 115.5(2), (b) 118.4(3)
(a) 117.6(3), (b) 116.9(3)
94.4(2)
97.3(2)
133.9(3)
129.7(3)
98.1(1)
132.4(3)
128.3(3)
99.2(1)
(a) 118.6(3), (b) 115.9(2)
91.1(1)
40.0(2)
40.3(2)
114.7(2)
107.1(1)
177.4(4)
100.1(1)
39.8(2)
113.4(2)
106.8(1)
179.4(4)
132.4(4)
132.9(4)
146.6(1)
146.2(1)
112.8(2)
107.4(1)
175.6(6)
100.5(2)
40.1(2)
111.1(2)
108.2(1)
176.7(5)
132.9(4)
133.7(4)
147.5(1)
148.4(1)
(a) 90.3(2), (b) 173.2(1)
178.1(3)
92.9(1)
39.6(1)
113.4(2)
109.4(1)
178.6(4)
132.5(3)
131.4(3)
149.90(9)
149.07(9)
(a) 173.6(2), (b) 90.3(2)
176.7(4)
(a) 123.8(3), (b) 127.2(3)
(a) 127.7(3), (b) 123.9(3)
(a) 178.6(1), (b) 94.8(1)
(a) 93.4(1), (b) 176.8(1)
a The letters a and b refer to the two hexafluorobutyne bridges (see Fig. 5).
[average 2.085(4) Å] are normal for σ-bonds.18 The Pt(1)–Pt(2)
separation of 3.218(1) Å is more than twice the covalent radius
of platinum, as found in [Pt2(CO)2( PBzPh2)2(µ-η1,η1-tBuO2-
Pt–Pt separations of 3.056(1)–3.096(1) Å in 1 and 3, in which
the µ-η2,η2-alkyne ligand prevents direct Pt–Pt bonding. In
compound 6, the two platinum atoms have a 16-electron con-
figuration and planar coordination [the mean deviations of the
t
10
᎐
CC᎐CCO Bu)] {2.638(8) Å}, and is comparable with the
᎐
2
3568
J. Chem. Soc., Dalton Trans., 2002, 3565–3570

View Article Online
Ϫ1
᎐
(cm ): CH Cl solution ν(C᎐O) 2031vs; Nujol mull ν(CF)
᎐
2
2
sym
1276s, ν(CF)deg 1172s, 1121s, 1099s.
2
2
᎐
[Pt (CO) (PBzPh ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF )] (2). Prepared as
᎐
2
2
2
2
3
3
for 1, starting with [Pt3(CO)3(PBzPh2)3] (0.27 g, 0.18 mmol) and
᎐
CF C᎐CCF (20 ml, 0.83 mmol). Yield: 0.198 g (63%) as ivory
᎐
3
3
crystals after crystallization from dichloromethane–heptane.
M.p. 102–107 ЊC dec. (Found: C, 45.85; H, 3.03; C44H34F6-
O2P2Pt2 requires C, 45.52; H, 2.95%). Selected IR data (cmϪ1):
᎐
CH Cl solution ν(C᎐O) 2029vs; Nujol mull ν(CF)
1275s,
᎐
2
2
sym
ν(CF)deg 1168s, 1118s, 1098s.
2
2
᎐
[Pt (CO) (PCy ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF )] (3). A suspension
᎐
2
2
3
2
3
3
of [Pt3(CO)3(PCy3)3] (0.332 g, 0.22 mmol) in dichloromethane
᎐
(20 ml) was cooled at Ϫ20 ЊC and gaseous CF C᎐CCF (25ml,
᎐
3
3
1.04 mmol) was added. The suspension was stirred for 10 min at
this temperature and then at room temperature. After 1 h, the
pale orange solution obtained was concentrated under vacuum
to ca. 2 ml. Addition of pentane (10 ml) and cooling at Ϫ22 ЊC
overnight afforded pale grey crystals of 3. Recrystallization
from dichloromethane–heptane at low temperature gave ivory
crystals suitable for X-ray diffraction studies (Yield: 0.251 g,
65%). M.p. 201–204 ЊC dec. (Found: C, 43.15; H, 5.60;
C42H66F6O2P2Pt2 requires C, 43.15; H, 5.69%). Selected IR data
Fig.
5
ORTEP representation at the 30% probability level of
1
1
᎐
[Pt2(CO)2(PR3)2(µ-η :η -CF3C᎐CCF3)2] (6).
᎐
coordinated atoms from the planes containing Pt(1) and Pt(2)
are 0.029 and 0.013 Å, respectively]; the interplanar angle is
82.8(1)Њ.
Ϫ1
᎐
(cm ): CH Cl solution ν(C᎐O) 2012vs; Nujol mull ν(CF)
᎐
2
2
sym
1272s, ν(CF)deg 1167s, 1109s, 1103s.
i
2
2
᎐
[Pt (CO) (P Pr ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF )] (4). A solution of
᎐
2
2
3
2
3
3
[Pt3(CO)3(PiPr3)3] (0.437 g, 0.38 mmol) in dichloromethane
(15 ml) was cooled at Ϫ20 ЊC and gaseous CF C᎐CCF (37 ml,
Experimental
᎐
᎐
3
3
General procedures
1.54 mmol) was added. After 30 min at room temperature, the
pale orange solution was evaporated to dryness and crude 4 was
treated with 5 ml of cold pentane. The ivory–ochre solid was
filtered and recrystallized from dichloromethane–heptane at
Ϫ22 ЊC overnight (Yield: 0.292 g, 55%). Selected IR data
All manipulations were carried out under nitrogen atmospheres
using standard Schlenk techniques. All solvents were dried by
conventional methods and distilled prior to use.
Infrared spectra of solids (KBr, Nujol mulls) and CH2Cl2
solutions (KBr or CaF2 cells) were recorded on Perkin-Elmer
983 or FT-IR-2000 spectrometers, and NMR spectra on Bruker
AC 200 (1H at 200.13 MHz, 31P at 81.02 MHz, and 13C at
50.32 MHz), Bruker WH 360 (13C at 90.55 MHz), or Bruker
DRX 400 (31P at 161.93 MHz, 13C at 100.6 MHz, and 19F at
376.4 MHz) spectrometers. The chemical shifts (δ) are referred
to Me4Si (1H and 13C), CFCl3 (19F) or external 85% H3PO4
Ϫ1
᎐
(cm ): CH Cl solution ν(C᎐O) 2016vs; Nujol mull ν(CF)
᎐
2
2
sym
1274s, ν(CF)deg 1165s, 1109s, 1100s.
1
1
᎐
[Pt (CO) (PPh ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF ) ] (5). A solution of
᎐
2
2
3
2
3
3 2
[Pt3(CO)3(PPh3)3] (0.195 g, 0.134 mmol) in dichloromethane
᎐
(25 ml) was cooled at Ϫ20 ЊC and gaseous CF C᎐CCF (55 ml,
᎐
3
3
2.29 mmol) was added. After 10 min at this teperature, the
solution was stirred at room temperature for 70 h. Concen-
tration of the resulting suspension to few ml, followed by addi-
tion of heptane (20 ml), gave a whitish solid. Recrystallization
from dichloromethane–heptane at low temperature afforded 5
as ivory microcrystals (Yield: 0.12 g, 46%). M.p. 222–225 ЊC
dec. (Found: C, 42.81; H, 2.32; C46H30F12O2P2Pt2 requires C,
(31P), respectively. The spectra of all nuclei (except H) were
1
1H decoupled. Simulations were performed with the gNMR 4.0
program, taking into account only the relative population of
platinum isotopomers, since all samples for 13C{1H}-NMR
were enriched to ≥99% 13CO.8 Microanalyses were obtained
from the Department of Inorganic, Metalorganic and
Analytical Chemistry, University of Padova.
42.67; H, 2.34%). Selected IR data (cmϪ1): CH2Cl2 solution
The compounds [Pt3(CO)3(PR3)3], where
L
=
PPh3,8
sym
᎐
ν(C᎐O) 2077vs; Nujol mull ν(CF)
1243s, 1224s, ν(CF)deg
᎐
PBzPh2,8,19 PCy3,20 and PiPr3 were prepared by literature
methods. The 13C isotopically labeled derivatives were prepared
similarly, using 13CO enriched to 99%. Hexafluoro-2-butyne
(Aldrich) and carbon monoxide (> 99% 13CO) were used as
received.
20
1134s, 1122s, 1098s.
1
1
᎐
[Pt (CO) (PBzPh ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF ) ] (6). Prepared as
᎐
2
2
2
2
3
3 2
for 5, starting with [Pt3(CO)3(PBzPh2)3] (0.132 g, 0.088 mmol)
᎐
and CF C᎐CCF (43 ml, 1.79 mmol). Yield: 0.077 g (44%)
᎐
3
3
as ivory microcrystals after recrystallization from dichloro-
methane–heptane. M.p. 215–218 ЊC dec. (Found: C, 43.34; H,
2.52; C48H34F12O2P2Pt2 requires C, 43.58; H, 2.59%). Selected
Syntheses
2
2
᎐
[Pt (CO) (PPh ) (ꢀ-ꢁ :ꢁ -CF C᎐CCF )] (1). A suspension of
Ϫ1
᎐
2
2
3
2
3
3
᎐
IR data (cm ): CH Cl solution ν(C᎐O) 2078vs; Nujol mull
᎐
2
2
[Pt3(CO)3(PPh3)3] (0.29 g, 0.20 mmol) in a 1:2 dichloro-
methane–heptane mixture (25 ml) was cooled to Ϫ10 ЊC and
gaseous CF C᎐CCF (15 ml, 0.62 mmol) was added with a
ν(CF)sym 1241s, 1226s, ν(CF)deg 1126s, 1118s, 1103s.
᎐
᎐
3
3
Crystal structures
syringe. The mixture was stirred for 10 min at this temperature
and then 1 h at room temperature. Concentration of the result-
ing solution, followed by addition of heptane and cooling over-
night at Ϫ22 ЊC gave a whitish solid. Recrystallization from
dichloromethane–isopropanol at low temperature afforded 1
as ivory crystals suitable for X-ray diffraction studies (Yield:
0.251 g, 74%). M.p. 163–166 ЊC dec. (Found: C, 44.53; H, 2.67;
C42H30F6O2P2Pt2 requires C, 44.80; H, 2.65%). Selected IR data
Crystal data for 1. A yellow crystal, of which the habitus
consisted of a {110} prism and a {001} pinacoid, was mounted
on a Bruker SMART CCD system equipped with Mo-Kα radi-
ation. A hemisphere of reflections was collected as ω scans over
12 h. Lattice constants were optimized using the SAINT21
package. C42H30F6O2P2Pt2; M/g molϪ1: 1132.78; crystal size/
mm: 0.62 × 0.33 × 0.14; T /K: 293(2); crystal system: triclinic;
J. Chem. Soc., Dalton Trans., 2002, 3565–3570
3569

View Article Online
¯
space group: P1; a/Å: 14.810(3); b/Å: 15.703(3); c/Å: 18.227(4);
See http://www.rsc.org/suppdata/dt/b2/b203075f/ for crystal-
lographic data in CIF or other electronic format.
α/Њ: 78.32(3); β/Њ: 77.49(3); γ/Њ: 88.93(3); V/Å3: 4051.1(14); Z: 4;
Dc/g cmϪ3: 1.857; F(000): 2152; µ/mmϪ1: 7.040; θ range/Њ: 2.44 to
27.99; reflections collected/unique: 46049/17658 [Rint = 0.0289];
variables: 973; R1: 0.0262, wR2 [I > 2σ(I)]: 0.0434.
Acknowledgements
We thank the Swiss National Science Foundation and Murst
Cofin-2001 for financial support.
Crystal data for 3. A yellow crystal, of which the habitus
¯¯
¯
consisted of {010}, {001}, {011}, {111}, {011} and {010}
pinacoids, was mounted on a Stoe IPDS system equipped with
Mo-Kα radiation. A crystal–image plate distance of 60 mm was
used and 240 images, in oscillation steps of 1Њ, were exposed for
3 min each. After inspection of reciprocal space, it was ascer-
tained that the diffraction figure consisted essentially of the
spots corresponding to the cell given below. For the integration,
a mosaic spread of 0.008 and spot sizes between 13 and 27
pixels were used. C42H66F6O2P2Pt2; M/g: molϪ1 1169.07; T /K:
293(2); crystal system: monoclinic; space group: P21/n; a/Å:
16.8390(11); b/Å: 15.3101(10); c/Å: 18.6194(12); β/Њ: 108.481(1);
V/Å3: 4552.7(5); Z: 4; Dc/g cmϪ3: 1.706; F(000): 2296; µ/mmϪ1:
6.266; θ range/Њ: 1.42 to 23.29; reflections collected/unique:
17087/6484 [Rint = 0.0212]; variables: 488; R1: 0.0207, wR2
[I > 2σ(I)]: 0.0426.
References
1 F. R. Hartley, Angew. Chem., Int. Ed. Engl., 1972, 11, 596.
2 F. G. A. Stone, Acc. Chem. Res., 1981, 14, 318.
3 G. B. Young, in Comprehensive Organometallic Chemistry II,
ed. E. W. Abel, F. G. A. Stone and G. Wilkinson, Pergamon, Oxford,
1995, vol. 9, p. 533.
4 N. M. Boag, M. Green and F. G. A. Stone, J. Chem. Soc.,
Chem. Commun., 1980, 1281.
5 N. M. Boag, M. Green, J. A. K. Howard and F. G. A. Stone,
J. Chem. Soc., Dalton Trans., 1991, 862.
6 G. J. Spivak and R. J. Puddephatt, J. Organomet. Chem., 1998, 551,
383.
7 (a) D. M. Hoffman, R. Hoffman and C. R. Fisel, J. Am. Chem. Soc.,
1982, 104, 3858; (b) D. M. Hoffman and R. Hoffman, J. Chem. Soc.,
Dalton Trans., 1982, 1471, and references therein.
8 R. Ros, A. Tassan, G. Laurenczy and R. Roulet, Inorg. Chim. Acta,
2000, 303, 94.
9 R. Ros, G. Facchin, A. Tassan, R. Roulet, G. Laurenczy and
F. Lukas, J. Cluster Sci., 2001, 12(1), 99.
Crystal data for 6. A pale yellow crystal, of which the habitus
¯
¯¯
consisted of a {110} prism, a {100} pinacoid, and (034), (056)
¯
and (105) pedions, was mounted on a Stoe IPDS system
10 R. Ros, A. Tassan, R. Roulet, V. Duprez, S. Detti, G. Laurenczy and
K. Schenk, J. Chem. Soc., Dalton Trans., 2001, 2858.
11 A. Moor, P. S. Pregosin and L. M. Venanzi, Inorg. Chim. Acta, 1981,
48, 153.
12 D. Carbona, R. Thouvenot, L. M. Venanzi, F. Bachechi and
L. Zambonelli, J. Organomet. Chem., 1983, 250, 589.
13 H. Rüegger and D. Moskau, Magn. Reson. Chem., 1991, 29, 511.
14 B. W. Davies and N. C. Payne, Inorg. Chem., 1974, 13, 1848.
15 J. F. Richardson and N. C. Payne, Can. J. Chem., 1977, 55, 3203.
16 D. H. Farrar and N. C. Payne, J. Organomet. Chem., 1981, 220, 239.
17 Spec. Publ. Chem. Soc., 1965, 18, S16s.
18 G. K. Anderson, in Comprehensive Organometallic Chemistry II,
ed. E. W. Abel, F. G. A. Stone, and G. Wilkinson, Pergamon,
Oxford, 1995, vol. 9, p. 445.
19 J. Chatt and P. Chini, J. Am. Chem. Soc., 1970, 1538.
20 K. H. Dalmer, A. Moor, R. Naegli and L. M. Venanzi, Inorg. Chem.,
1991, 30, 4285.
21 SAINT, Programme for the Reduction of Data from an Area
Detector, version 4.05, Bruker Analytical X-Ray Instruments, Inc,
Madison, WI, USA, 1996.
22 G. M. Sheldrick, SHELXTL 5.05, Bruker Analytical X-Ray
Instruments, Inc, Madison, WI, USA, 1996.
23 P. T. Beurskens, G. Beurskens, W. P. Bosman, R. de Gelder,
S. García-Granda, R. O. Gould, R. Israël and M. M. Smits,
The DIRDIF-96 System of Programmes, Laboratorium voor
Kristallografie, Katholieke Universiteit Nijmegen, 1996.
equipped with Mo-Kα radiation. A crystal–image plate dis-
tance of 60 mm was used and 164 images, in oscillation steps of
1Њ, were exposed for 5 min each. After inspection of reciprocal
space, it was ascertained that the diffraction figure consisted
essentially of the spots corresponding to the cell given below.
For the integration, a mosaic spread of 0.007 and spot sizes
between 13 and 19 pixels were used. C48H34F12O2P2Pt2; M/g
molϪ1: 1322.87; T /K: 293(2); crystal system: monoclinic; space
group: P21/c; a/Å: 13.001(3); b/Å: 13.740(3); c/Å: 26.580(5); β/Њ:
104.03(3); V/Å3: 4606(2); Z: 4; Dc/g cmϪ3: 1.908; F(000): 2528;
µ/mmϪ1: 6.224; θ range/Њ: 2.46 to 28.06; reflections collected/
unique: 35396/10541 [Rint 0.0298]; variables: 646; R1: 0.0270,
wR2: [I > 2σ(I)] 0.0402.
For all measurements, intensities were corrected for Lorentz
and polarization effects. An absorption correction based on the
crystal habiti were computed with the help of the XPREP22
program. The decay during the measurements was negligible.
The structures were solved with the help of DIRDIF-96,23 and
refined by means of SHELXTL 5.05.22 All non-hydrogen atoms
were refined anisotropically, and all hydrogens, which were
made to ride on their associated carbons, isotropically.
CCDC reference numbers 183074–183076.
3570
J. Chem. Soc., Dalton Trans., 2002, 3565–3570