Slippage of η3-allenyl/propargyl to an η1 structure and tautomerization of η1-propargyl to η1-allenyl in ligand addition and substitution reactions of platinum(II) complexes

Article abstract of DOI:10.1016/S0020-1693(01)00493-5

Reactions of [(PPh₃)₂Pt(η³-CH₂CCPh)]OTf with each of PMe₃, CO and Br^- result in the addition of these species to the metal and a change in hapticity of the η³-CH₂CCPh to η¹-CH₂C≡CPh or η¹-C(Ph)=C=CH₂. Thus, PMe₃ affords [(PMe₃)₃Pt(η¹-C(Ph)=C=CH₂)] ⁺, CO gives both [trans-(PPh₃)₂Pt(CO)(η¹-CH₂ C≡CPh)]⁺ and [trans-(PPh₃)₂Pt(CO)(η¹-C(Ph)=C=CH ₂)]⁺, and LiBr yields cis-(PPh₃)₂PtBr(η¹-CH₂ C≡CPh), which undergoes isomerization to trans-(PPh₃)₂PtBr(η¹-CH₂ C≡CPh). Substitution reactions of cis- and trans-(PPh₃)₂PtBr(η¹-CH₂ C≡CPh) each lead to tautomerization of η¹-CH₂C≡CPh to η¹-C(Ph)=C=CH₂, with trans-(PPh₃)₂PtBr(η¹-CH₂ C≡CPh) affording [(PMe₃)₃Pt(η¹-C(Ph)=C=CH₂)] ⁺ at ambient temperature and the slower reacting cis isomer giving [trans-(PPh₃)(PMe₃)₂Pt(η¹- C(Ph)=C=CH₂)]⁺ at 54°C . All new complexes were characterized by a combination of elemental analysis, FAB mas spectrometry and IR and NMR (¹H, ¹³C{¹H} and ³¹P{¹H}) spectroscopy. The structure of [(PMe₃)₃Pt(η¹-C(Ph)=C=CH₂)] BPh₄·0.5MeOH was determined by single-crystal X-ray diffraction analysis.

Full text of DOI:10.1016/S0020-1693(01)00493-5

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Inorganica Chimica Acta 320 (2001) 110–116
Slippage of h3-allenyl/propargyl to an h1 structure and
tautomerization of h1-propargyl to h1-allenyl in ligand addition
and substitution reactions of platinum(II) complexes
Patrick W. Blosser a, Mario Calligaris b,1, David G. Schimpff a, Andrew Wojcicki a,*
a Department of Chemistry, The Ohio State Uni6ersity, 100 West 18th A6enue, Columbus, OH 43210-1185, USA
b Dipartimento di Scienze Chimiche, Uni6ersita` di Trieste, 34127 Trieste, Italy
Received 30 March 2001; accepted 27 April 2001
Abstract
Reactions of [(PPh3)2Pt(h3-CH2CCPh)]OTf with each of PMe3, CO and Br− result in the addition of these species to the metal
and a change in hapticity of the h3-CH2CCPh to h1-CH2CꢀCPh or h1-C(Ph)ꢁCꢁCH2. Thus, PMe3 affords [(PMe3)3Pt(h1-
C(Ph)ꢁCꢁCH2)]+, CO gives both [trans-(PPh3)2Pt(CO)(h1-CH2CꢀCPh)]+ and [trans-(PPh3)2Pt(CO)(h1-C(Ph)ꢁCꢁCH2)]+, and
LiBr yields cis-(PPh3)2PtBr(h1-CH2CꢀCPh), which undergoes isomerization to trans-(PPh3)2PtBr(h1-CH2CꢀCPh). Substitution
reactions of cis- and trans-(PPh3)2PtBr(h1-CH2CꢀCPh) each lead to tautomerization of h1-CH2CꢀCPh to h1-C(Ph)ꢁCꢁCH2, with
trans-(PPh3)2PtBr(h1-CH2CꢀCPh) affording [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]+ at ambient temperature and the slower reacting cis
isomer giving [trans-(PPh3)(PMe3)2Pt(h1-C(Ph)ꢁCꢁCH2)]+ at 54 °C . All new complexes were characterized by a combination of
elemental analysis, FAB mas spectrometry and IR and NMR (1H, 13C{1H} and 31P{1H}) spectroscopy. The structure of
[(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4·0.5MeOH was determined by single-crystal X-ray diffraction analysis. © 2001 Elsevier
Science B.V. All rights reserved.
Keywords: Platinum complexes; Allenyl complexes; Propargyl complexes; Crystal structure
unusual chemical behavior toward nucleophilic reagents
which add to the central carbon atom of the hydrocar-
1. Introduction
byl ligand [1,7a,b,9–11]. However, reactions are also
In recent years a number of papers have dealt with
known which result in addition of nucleophile/ligand to
transition-metal h1-propargyl–h1-allenyl tautomerism
the metal center with rearrangement of the h3-allenyl/
[1–8]. These processes are thought to proceed by inter-
propargyl to h1-allenyl or h1-propargyl [1,7a,12].
mediacy of a metal h3-allenyl/propargyl, and in some
Transformations of this type are important, since they
cases evidence exists for such a pathway.
can provide insight into h1-propargyl–h1-allenyl tau-
h3-Allenyl/propargyl complexes of transition metals
tomerism in transition-metal complexes. In this paper
have attracted considerable attention because of their
we report on such reactions of [(PPh3)2Pt(h3-
CH2CCPh)]+ as well as on h1-propargyl to h1-allenyl
tautomerization in the course of ligand substitution
reactions of cis- and trans-(PPh3)2PtBr(h1-CH2CꢀCPh).
* Corresponding author. Tel.: +1-614-292 4750; fax: +1-614-292
1685.
E-mail addresses: calligaris@univ.trieste.it (M. Calligaris), wojci-
An X-ray structural study of [(PMe3)3Pt(h1-
C(Ph)ꢁCꢁCH2)]BPh4 is described. Some aspects of our
cki.1@osu.edu (A. Wojcicki).
1 To whom inquiries concerning the X-ray crystallographic studies
investigation (but not the structure) have already been
communicated [7a].
should be addressed. Fax: +39-40-676 3903.
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00493-5

P.W. Blosser et al. / Inorganica Chimica Acta 320 (2001) 110–116
111
3
1
2. Experimental
2.0 Hz, JPtC=45 Hz, JCH=167 Hz, CH2), 18.1 (dt,
1JPbC=33.5 Hz, 3JPaC=2.1 Hz, 2JPtC=25.8 Hz,
PbMe3), 16.0 (td, 1JPaC=19.9 Hz, 3JPbC=2.3 Hz,
2.1. General procedures, measurements and materials
2JPtC=35.1
Hz,
PaMe3).
31P{1H}
NMR
2
1
Reactions and sample manipulations were generally
conducted under an atmosphere of argon by use of
standard procedures [13]. Solvents were dried [14], dis-
tilled under argon and degassed before use. Elemental
analyses were performed by M-H-W Laboratories,
Phoenix, AZ. IR, NMR (1H, 13C{1H} and 31P{1H})
and FAB mass spectra were obtained as previously
described [7].
(CD3C(O)CD3): l −21.2 (d, JPP=23.7 Hz, JPtP
=
=
2488 Hz, PaMe3), −28.3 (t, 2JPP=23.7 Hz, JPtP
1
1991 Hz, PbMe3). FAB MS: 195Pt, m/z 538 (M+), 423
(M+−C3H2Ph), 347 (M+−C3H2Ph–PMe3). Anal.
Found: C, 58.63; H, 6.38. Calc. for C42H54BP3Pt: C,
58.81; H, 6.35%.
Reagents were procured from various commercial
sources and used as received. The complexes cis- and
trans-(PPh3)2PtBr(h1-CH2ꢀCPh) and [(PPh3)2Pt(h3-
CH2CCPh)]OTf (OTf=O3SCF3) were prepared by our
published procedures [7b].
2.3. Reaction of cis-(PPh3)2PtBr(p1-CH2CꢀCPh) with
PMe3
2.2. Reaction of trans-(PPh3)2PtBr(p1-CH2CꢀCPh)
with PMe3
A stirred solution of cis-(PPh3)2PtBr(h1-CH2CꢀCPh)
(0.330 g, 0.361 mmol) in 50 ml of THF at 54 °C was
treated with PMe3 in toluene (10.0 ml, 1.0 M, 10
mmol). The resulting solution was stirred for 10 h, and
the white precipitate that had formed was collected on
a filter frit and converted to the BPh−4 salt in a manner
analogous to that described above for [(PMe3)3Pt(h1-
C(Ph)ꢁCꢁCH2)]BPh4. Yield of [trans-(PPh3)(PMe3)2Pt-
(h1-C(Ph)ꢁCꢁCH2)]BPh4, 0.183 g (49%). IR (Nujol):
A solution of PMe3 in toluene (3.0 ml, 1.0 M, 3.0
mmol) was added to trans-(PPh3)2PtBr(h1-CH2CꢀCPh)
(0.654 g, 0.715 mmol) dissolved in 40 ml of THF at
room temperature. The resulting yellow solution began
to cloud after several minutes and was stirred vigor-
ously for 18 h. The white precipitate that formed during
this time was collected on a filter frit and washed with
20 ml of hexane, and the yellow–orange filtrate was
discarded. The precipitate was dissolved in 2 ml of
MeOH in air, and the solution was filtered into a flask
containing NaBPh4 (0.300 g, 0.877 mmol) in 1.5 ml of
MeOH. The voluminous ivory precipitate was collected
on a filter frit, washed with 60 ml of hexane and dried
briefly. This product was found to contain some salt
impurities which were removed by addition of 100 ml
of CH2Cl2 and filtration of the cloudy solution through
a 2×2 cm column of wet Celite. The filtrate was
concentrated to 10 ml under vacuum, and hexane (100
ml) was introduced with stirring to induce the precipita-
tion of the ivory product. After reducing the mixture
volume to 50 ml, the solid was collected on a filter frit,
washed with 20 ml of hexane and dried under vacuum
overnight. Yield of [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4,
0.475 g (78%). IR (Nujol): w(CꢁCꢁC) 1908 cm−1 (m).
1H NMR (CD3C(O)CD3): l 7.62–6.75 (m, 25H, Ph),
1
w(CꢁCꢁC) 1908 cm−1 (m). H NMR (CD3C(O)CD3): l
5
4
8.00–6.75 (m, 40H, Ph), 4.44 (q, JPH=1.8 Hz, JPtH
=
2
3
13.7 Hz, 2H, CH2), 1.11 (t, JPH=3.9 Hz, JPtH=28.2
Hz, 18H, PMe3). 31P{1H} NMR (CD3C(O)CD3): l 15.1
2
1
(t, JPP=23.5 Hz, JPtP=2153 Hz, PPh3), −21.9 (d,
2JPP=23.5 Hz, JPtP=2486 Hz, PMe3).
1
2.4. Reaction of [(PPh3)2Pt(p3-CH2CCPh)]OTf with
PMe3
To a stirred solution of [(PPh3)2Pt(h3-CH2CCPh)]-
OTf (0.090 g, 0.092 mmol) in 30 ml of THF at 0 °C
was added dropwise a solution of PMe3 in toluene (1.2
ml, 1.0 M, 1.2 mmol). After 20 h of reaction time,
during which the temperature was allowed to rise to
25 °C , solvent was removed, the residue was treated
with 40 ml of hexane and the resulting mixture was
stirred for 2 h. The contents were filtered, and the
filtrate was discarded. The collected solid was extracted
into 10 ml of acetone, and the extract was filtered and
evaporated to dryness under vacuum. The remaining
solid was dissolved in MeOH, and the resulting solution
was treated with ca. 0.1 g (0.3 mmol) of NaBPh4. The
rest of the work-up closely followed that given in
Section 2.2. Yield of [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]-
BPh4, 0.048 g (62%). Spectroscopic properties of the
5
4
4.26 (q, JPH=5.4 Hz, JPtH=38.0 Hz, 2H, CH2), 1.85
2
3
(d, JPH=9.3 Hz, JPtH=21.7 Hz, 9H, PbMe3), 1.60 (t,
2JPH=3.8 Hz, JPtH=28.9 Hz, 18H, PaMe3). 13C{1H}
3
3
NMR (CD3C(O)CD3): l 202.4 (t, JPC=4 Hz, unre-
solved JPtC, ꢁCꢁ), 164.9 (qsept, 1JC11B=49.6 Hz,
2
1JC10B=14.4 Hz, ipso-PhB), 142.7 (t, JPaC=1.6 Hz,
3
2JPtC=16 Hz, ipso-PhC), 137.0 (m, m-PhB), 129.9 (s,
o-PhC), 127.3 (s, p-PhC), 126.0 (m, o-PhB), 122.2 (s,
p-PhB), 101.6 (dt, 2JPbC=90 Hz, 2JPaC=12 Hz,
1JPtC=603 Hz, PhC), 69.9 (dt, JPbC=6.4 Hz, JPaC
=
4
4

112
P.W. Blosser et al. / Inorganica Chimica Acta 320 (2001) 110–116
1
product matched those of the sample prepared from
OTf (B), 0.174 g (81%). H NMR (CD2Cl2): l 8.0–6.6
5
4
trans-(PPh3)2PtBr(h1-CH2CꢀCPh) and PMe3.
(m, Ph), 3.65 (t, JPH=4.7 Hz, JPtH=38 Hz, CH2 of
3
2
B), 1.98 (t, JPH=9.7 Hz, JPtH=83 Hz, CH2 of A).
2.5. Reaction of [(PPh3)2Pt(p3-CH2CCPh)]OTf with
CO
13C{1H} NMR (CD2Cl2): l 203.1 (t, JPC=4.8 Hz, ꢁCꢁ
3
2
2
of B), 175.2 (t, JPC=9.0 Hz, CO), 174.5 (t, JPC=10.1
Hz, CO), 138–123 (m, Ph), 101.5 (t, 2JPC=8.9 Hz, PhC
of B), 92.2 (s, 3JPtC=78 Hz, PhC of A), 72.9 (s,
Carbon monoxide was passed into a stirred solution
of [(PPh3)2Pt(h3-CH2CCPh)]OTf (0.208 g, 0.211 mmol)
in 4 ml of CH2Cl2 at room temperature. After 2 h,
hexane (20 ml) was added, and the resulting solution
was concentrated to 15 ml to induce the precipitation of
a bright yellow solid. The solid was collected on a filter
frit and dried under vacuum overnight. Yield of a ca.
1:1 mixture of [trans-(PPh3)2Pt(CO)(h1-CH2CꢀCPh)]-
OTF (A) and [trans-(PPh3)2Pt(CO)(h1-C(Ph)ꢁCꢁCH2)]-
3JPtC=40 Hz, CH2 of B), 7.1 (t, JPC=3 Hz, JPtC
=
2
1
484 Hz, CH2 of A). 31P{1H} NMR (CD2Cl2): l 17.6 (s,
1JPtP=2677 Hz), 14.3 (s, JPtP=2573 Hz).
1
2.6. Reaction of [(PPh3)2Pt(p3-CH2CCPh)]OTf with
LiBr
A solution of [(PPh3)2Pt(h3-CH2CCPh)]OTf (ca. 30
mg) in 15 ml of 2:1 THF–CH2Cl2 was treated with
LiBr (ca. 10 mg), and the contents were stirred for 1 h
at room temperature. The reaction solution was then
concentrated to 3 ml, and its 31P{1H} NMR spectrum
was recorded. The spectrum showed signals which were
assigned to cis- and trans-(PPh3)2PtBr(h1-CH2CꢀCPh)
in ca. 9:1 ratio on the basis of published data for
authentic samples [7b].
Table 1
Summary of crystal data, data collection and structure refinement
parameters for [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4·0.5MeOH
Empirical formula
Formula weight
Crystal system
C42H54BP3Pt·0.5CH4O
873.73
triclinic
(
Space group
Unit cell dimensions
P1
,
a (A)
9.770(2)
20.965(4)
21.459(4)
104.13(1)
,
b (A)
2.7. Crystallographic analysis of
,
c (A)
h (°)
i (°)
[(PMe3)3Pt(p1-C(Ph)ꢁCꢁCH2)]BPh4·0.5MeOH
96.68(1)
k (°)
98.54(1)
4161(1)
4
1.39
Crystals
of
[(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4·
3
,
V (A )
0.5MeOH were grown from acetone–methanol solution
by slow evaporation of the solvent. Lattice constants
were determined by a least-squares refinement of 25
reflections, accurately centered on an Enraf–Nonius
CAD4 diffractometer. A summary of the crystal data
and the details of the intensity data collection and
refinement are provided in Table 1. No significant
change in intensities of control reflections was observed
over the course of data collection. The data were
corrected for Lorentz polarization effects, as well as for
absorption, through an empirical correction based on
the C scans of four close-to-axial reflections. The struc-
ture was solved by conventional Fourier methods. Final
full-matrix least-squares refinement, with the fixed con-
tribution of the hydrogen atoms (B=1.3Beq A ), con-
verged to the R and Rw values given in Table 1.
Scattering factors, anomalous dispersion terms, and
programs were taken from the Enraf–Nonius SDP
library [15].
Z
Dcalc (g cm−3
Crystal size (mm)
Diffractometer
)
0.4×0.4×0.6
Enraf–Nonius CAD4
0.71069 (graphite-monochromated Mo
Ka)
29491
35.50
1808
ꢀ/2q
1–7
2.0–24.0
0.95+0.35tanq
1+tanq
3
0.882–1.000
13409
,
u (A)
Temperature (K)
v (cm−1
F(000)
)
Scan type
ꢀ Scan rate (° min−1
q Range (°)
)
Scan angle (°) a
Aperture width
Intensity monitors
Transmission factors
Data collected b
Unique data with
I\3|(I)
2
,
10067
c
R
0.030
0.036
1
d
Rw
w
GOF e
2.697
Residuals in final map
−0.12, 0.71
−3
,
(e A
)
3. Results and discussion
a Extended by 25% on both sides for background measurements.
b Measured after each 4000 s.
3.1. Reactions of platinum(II) complexes with PMe3
c R=ꢀꢁFo−Fcꢁ/ꢀꢁFoꢁ.
2 1/2
d Rw=[ꢀw(ꢁFoꢁ−ꢁFcꢁ)2/ꢀwꢁFoꢁ ]
.
Reaction of [(PPh3)2Pt(h3-CH2CCPh)]OTf with a
large excess PMe3 in THF first at 0 °C and then at
e GOF=[ꢀw(ꢁFoꢁ−ꢁFcꢁ)2/(m−n)]1/2
n=number of variables.
; m=number of observables,

P.W. Blosser et al. / Inorganica Chimica Acta 320 (2001) 110–116
113
material was still incompletely consumed. Identification
of these transients was not possible but, based on the
chemical shifts, they appear to be the result of succes-
sive substitutions of PMe3 for PPh3 at platinum. In
contrast, when the reaction was conducted at 40 °C for
4 h, only one major product was observed by 31P{1H}
NMR spectroscopy. This product was prepared on a
larger scale by reacting cis-(PPh3)2PtBr(h1-CH2CꢀCPh)
with an excess of PMe3 in THF at 54 °C , and was
isolated as the white BPh4 salt [trans-(PPh3)(PMe3)2-
−
Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4 in 49% yield (Eq. (2)).
(2)
The remaining PPh3 in the product undergoes grad-
ual substitution by PMe3 at ambient temperature to
afford [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4.
Scheme 1. Ligand addition reactions of [(PPh3)2Pt(h3-CH2CCPh)]+
.
The product [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4 was
characterized by IR and NMR (1H, 13C{1H} and
31P{1H}) spectroscopy, FAB mass spectrometry and
elemental analysis. Its structure was determined by
X-ray diffraction analysis. The mixed-phosphine com-
25 °C for a total of 40 h afforded [(PMe3)3Pt(h1-
C(Ph)ꢁCꢁCH2)]+, which was isolated as [(PMe3)3Pt(h1-
C(Ph)ꢁCꢁCH2)]BPh4 in 62% yield (Scheme 1).
The h1-allenyl product can be prepared more conve-
niently and in a higher yield by treatment of trans-
(PPh3)2PtBr(h1-CH2CꢀCPh) with ca. 4 equiv. of PMe3
in THF at room temperature for 18 h. Work-up and
addition of NaBPh4 in MeOH, as detailed in Section
2.4, gave [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2]BPh4 as an ivory
solid in 78% yield (Eq. (1)).
plex
[trans-(PPh3)(PMe3)2Pt(h1-C(Ph)ꢁCꢁCH2]BPh4
1
was assigned structure on the basis of IR and H and
31P{1H} spectroscopic evidence. Each complex shows
an IR w(CꢁCꢁC) absorption at 1908 cm−1 and a H
1
NMR signal of the CH2 at l 4.44–4.26 as a quartet
(5JPH=1.8–5.4 Hz) with platinum-195 satellites, which
implicates h1-allenyl bonding of the hydrocarbyl group
[1–7,16–20]. The former complex contains inequivalent
PMe3 ligands as evidenced by two Me proton reso-
nances, a doublet (2JPH=9.3 Hz) at l 1.85 and a triplet
(2JPH=3.8 Hz) at l 1.60, each with platinum-195 satel-
lites, in a 1:2 intensity ratio, and two 31P{1H} reso-
nances, a doublet at l −21.2 and a triplet at l −28.3,
with 2JPP=23.7 Hz and 1JPtP=2488 and 1991 Hz,
respectively. The PPh3–PMe3 complex shows only one
(1)
Use of cis-(PPh3)2PtBr(h1-CH2CꢀCPh) in conjunc-
tion with PMe3 in THF also furnished [(PMe3)3Pt(h1-
C(Ph)ꢁCꢁCH2)]+, but the reaction was slower than that
of trans-(PPh3)2PtBr(h1-CH2CꢀCPh). The correspond-
ing chloride cis-(PPh3)2PtCl(h1-CH2CꢀCPh) can be em-
ployed as well; however, it has a lower solubility in
THF and does not react as cleanly as the cis and trans
bromides. This general synthetic methodology is appli-
cable also to complexes [(PR3)3Pt(h1-C(Ph)ꢁCꢁCH2)]+
containing some other phosphines; e.g. [(PMe2Ph)3Pt-
(h1-C(Ph)ꢁCꢁCH2)]+ was prepared by a similar treat-
ment of trans-(PPh3)2PtBr(h1-CH2CꢀCPh) with an ex-
cess of PMe2Ph in THF.
1
kind of PMe3 ligand by the appearance of a H reso-
nance at l 1.11 as a triplet (2JPH=3.9 Hz) with plat-
inum-195 satellites. Its 31P{1H} NMR spectrum consists
of two signals, a triplet at l 15.1, assigned to PPh3, and
2
a doublet at l −21.9, assigned to PMe3, with JPP
=
23.5 Hz and 1JPtP=2153 and 2486 Hz, respectively,
to indicate trans structure for the cation
a
[(PPh3)(PMe3)2Pt(h1-C(Ph)ꢁCꢁCH2)]+. The 13C{1H}
NMR spectrum of [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4
is in complete accord with the assigned structure [2,4–
6,16,18–20]. Resonances of the hydrocarbyl ligand oc-
cur at l 202.4 for ꢁCꢁ, l 101.6 with two different
The reaction of cis-(PPh3)2PtBr(h1-CH2CꢀCPh) with
an excess of PMe3 in THF at room temperature was
monitored by 31P{1H} NMR spectroscopy. A number
of intermediate platinum(II) phosphine complexes had
been observed in 18 h, after which time the starting
2
coupling constants JPC, 90 (trans) and 12 Hz (cis), and
1
a very large JPtC of 603 Hz for PhC, and l 69.9 with

114
P.W. Blosser et al. / Inorganica Chimica Acta 320 (2001) 110–116
sis on the [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4 obtained
from acetone–methanol as the 0.5MeOH solvate. The
crystals were found to contain two crystallographically
independent molecules, A and B; the structure of com-
plex cation A is shown in Fig. 1. Selected bond dis-
tances and angles are listed in Table 2.
3
1
2JPC=6.4 and 2.0 Hz, JPtC=45 Hz, and JCH=167
Hz (1H-coupled spectrum) for CH2. There are also
separate resonances of the PMe3 carbons for Pa and Pb
(cf. Section 2.4 for a, b designations) at l 18.1 and 16.0,
1
respectively, with appropriate coupling constants JPC
,
3JPC and 1JPtC. The FAB mass spectrum shows peaks of
the complex cation (M+) and fragments derived by loss
of C3H2Ph and of C3H2Ph plus PMe3.
The platinum is bonded to one h1-(1-phenylallenyl)
and three PMe3 ligands whose donor atoms adopt
approximately square planar geometry around the
metal. The bond angles around the Pt center vary from
83.8(2)–87.1(2)° between phosphorus and carbon, i.e.
for P(1)–Pt–C(3) and P(2)–Pt–C(3), to 93.97(9)–
95.00(8)° between two phosphorus atoms, i.e. for P(1)–
Pt–P(3) and P(2)–Pt–P(3). The sum of these bond
angles is 360.9 and 360.2° in molecules A and B,
respectively, and the deviations from the least-squares
plane defined by Pt and the four donor atoms are: Pt
0.003, P(1) 0.136, P(2) 0.140, P(3) −0.119 and C(3)
Since there are few published structures of mononu-
clear transition-metal h1-allenyl complexes [18b,19–21],
especially if the phosphoniumallenylidene analogs [22]
are excluded, we carried out an X-ray diffraction analy-
,
−0.159 A for molecule A; and Pt 0.003, P(1) −0.072,
,
P(2) −0.073, P(3) 0.063 and C(3) 0.081 A for molecule
,
B. The Pt–P bond distances of 2.313(2)–2.326(2) A are
similar to those reported for a number of platinum(II)
bromo a,b-unsaturated hydrocarbyl phosphine com-
plexes [19,20]. There is no difference in the Pt–P bond
distance for the two trans phosphines and the phos-
Fig. 1. Molecular structure of [(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2]+ with
,
phine trans to carbon. The Pt–C bond of 2.084(9) A for
,
50% probability ellipsoids. Hydrogen atoms have been omitted.
molecule A and 2.090(9) A for molecule B is longer
,
than a normal Pt–Csp2 bond of 1.98 A [23]. However, it
Table 2
is very similar to that reported for another platinum(II)
,
Selected bond distances (A), bond angles (°) and torsion angles (°) for
h1-allenyl
complex,
trans-(PPh3)2PtBr(h1-CHꢁCꢁ
[(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4·0.5MeOH
,
CMe2), which measures 2.10(3) A [19], and close to that
found in trans-(PPh3)2PtBr(h1-CHꢁCꢁCH2), i.e.
Molecule A
Molecule B
,
2.040(5) A [20].
The h1-allenyl fragment C(1)C(2)C(3) is linear
(178(1)°), and the bond distances C(1)–C(2) (1.34(1) A
for molecule A and 1.31(2) A for molecule B) and
C(2)–C(3) (1.31(1) A for molecule A and 1.30(1) A for
molecule B) are normal [18b,19–21]. The average an-
gles Pt–C(3)–C(2), Pt–C(3)–C(4) and C(2)–C(3)–C(4)
are very close to 120°, summing up, as expected, to
360.0° for both molecules A and B. The PtC(3)C(2)
plane is perpendicular to the least-squares plane
PtP(1)P(2)P(3)C(3), with the dihedral angle being 89.9°
for molecule A and 92.2° for molecule B.
Pt–P(1)
Pt–P(2)
Pt–P(3)
Pt–C(3)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
2.319(2)
2.326(2)
2.314(3)
2.084(9)
1.34(1)
1.31(1)
1.48(1)
2.316(2)
2.313(2)
2.320(3)
2.090(9)
1.31(2)
1.30(1)
1.47(1)
,
,
,
,
P(1)–Pt–P(2)
P(1)–Pt–P(3)
P(1)–Pt–C(3)
P(2)–Pt–P(3)
P(2)–Pt–C(3)
P(3)–Pt–C(3)
Pt–C(3)–C(2)
Pt–C(3)–C(4)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
168.26(9)
95.00(8)
87.1(2)
94.99(9)
83.8(2)
172.3(2)
121.2(7)
118.4(6)
178(1)
170.6(1)
94.80(8)
86.2(2)
93.97(9)
85.2(2)
176.3(3)
118.4(7)
119.8(6)
178(1)
3.2. Other reactions of platinum(II) complexes
120.4(8)
121.8(9)
The complex [(PPh3)2Pt(h3-CH2CCPh)]OTf reacts
with CO in CH2Cl2 solution at room temperature to
afford a ca. 1:1 mixture of [trans-(PPh3)2Pt(CO)(h1-
P(1)–Pt–C(3)–C(2)
P(1)–Pt–C(3)–C(4)
P(2)–Pt–C(3)–C(2)
P(2)–Pt–C(3)–C(4)
P(3)–Pt–C(3)–C(2)
P(3)–Pt–C(3)–C(4)
Pt–C(3)–C(4)–C(5)
C(2)–C(3)–C(4)–C(5)
−86.6(7)
95.5(6)
86.0(7)
−92.0(6)
168(1)
−11(2)
159.2(7)
−19(1)
−90.1(8)
92.0(7)
85.9(8)
−92.1(7)
164(3)
−14(4)
163.9(7)
−14(1)
CH2CꢀCPh)]OTf
and
[trans-(PPh3)2Pt(CO)(h1-
C(Ph)ꢁCꢁCH2)]OTf in 81% yield (Scheme 1). Efforts to
separate these two complexes, or to convert the mixture
to one isomer by heating, repeatedly were thwarted by
accompanying decomposition.

P.W. Blosser et al. / Inorganica Chimica Acta 320 (2001) 110–116
115
The presence of both the h1-propargyl [trans-
(PPh3)2Pt(CO)(h1-CH2CꢀCPh)]+ and the h1-allenyl
[trans-(PPh3)2Pt(CO)(h1-C(Ph)ꢁCꢁCH2]+ in the iso-
suggest that the anionic and the neutral adding species
interact differently with the substrate complex
[(PPh3)2Pt(h3-CH2CCPh)]+. Whereas the anions be-
cause of their charge probably approach the metal in
the vicinity of the h3-CH2CCPh group to give a cis
product, a point also made by Kurosawa [12b], neutral
species may enter in between the two PPh3 ligands. Of
course, such a proposal assumes that there is no cis
addition followed by rapid cis-to-trans product isomer-
ization for the latter group of incoming ligands, i.e. CO
and CNCMe3, and this point has not been demon-
strated. The formation of h1-allenyl and/or h1-propar-
gyl adducts may be due to several factors which include
a preference for ligand addition to platinum at the CH2
or the CPh side of the h3-CH2CCPh group and opti-
mization of the overall (s and p) bonding in the
product. Clearly, additional studies on an expanded
range of reacting ligands must be conducted before
some of these points are resolved.
1
lated solid is indicated by its H, 13C{1H} and 31P{1H}
1
NMR spectra. Thus, the H NMR spectrum shows two
CH2 triplets (owing to JPH coupling), that of the
PtC(Ph)ꢁCꢁCH2 at l 3.65 and that of the PtCH2CꢀCPh
at l 1.98. These chemical shifts are characteristic of the
two tautomeric structures [1–6,16–20], and the magni-
tude of JPtH coupling for the allenyl (38 Hz) is smaller
than that for the propargyl (83 Hz), as expected [1–
3,6–8,18–20]. The 13C{1H} NMR spectrum shows
characteristic signals of the allenyl ꢁCꢁ at l 203.1
[1,4–8,16,18–20] and of the propargyl CH2 at l 7.1
1
[1,6–8,16,18], the latter with a large JPtC constant of
484 Hz to indicate PtꢂCH2 bonding. There are two CO
resonances at l 175.2 and 174.5. The remaining signals
also are readily assignable to the allenyl and propargyl
species (Section 2.5). The occurrence of two 31P{1H}
resonances at l 17.6 and 14.3 as singlets with slightly
1
different JPtP coupling constants of 2677 and 2573 Hz,
4. Supplementary material
respectively, accords with the presence of the two tau-
tomeric species and their trans structures.
Crystallographic data for the structure of
The foregoing products of the reaction of
[(PPh3)2Pt(h3-CH2CCPh)]OTf with CO are analogous
to those of the corresponding reaction with the isoni-
trile CNCMe3 [24]. The latter also gives the h1-propar-
[(PMe3)3Pt(h1-C(Ph)ꢁCꢁCH2)]BPh4·0.5MeOH
have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 159531. Copies of the data can
be obtained free of charge from The Director, CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
gyl
and
h1-allenyl,
[trans-(PPh3)2Pt(CNCMe3)-
(h1-CH2CꢀCPh)]OTf and [trans-(PPh3)2Pt(CNCMe3)-
(h1-C(Ph)ꢁCꢁCH2)]OTf, respectively, but in the ratio
\6:1.
In contrast to the aforementioned reactions of
[(PPh3)2Pt(h3-CH2CCPh)]OTf with CO and CNCMe3,
treatment of the h3-allenyl/propargyl complex with
LiBr in THF–CH2Cl2 affords only h1-propargyl prod-
ucts. Thus, after 1 h at room temperature a ca. 9:1
mixture of cis- and trans-(PPh3)2PtBr(h1-CH2CꢀCPh)
was obtained (Scheme 1) which was characterized in
situ by 31P{1H} NMR spectroscopy. Since cis-
(PPh3)2PtBr(h1-CH2CꢀCPh) undergoes isomerization to
trans-(PPh3)2PtBr(h1-CH2CꢀCPh) under these condi-
tions, it is likely that the initial product of Br− addition
is exclusively the cis isomer. In a related study,
Kurosawa and co-workers recently reported [12b] that
[(PPh3)2Pt(h3-CH2CCPh)]OTf readily adds Cl− in
CD2Cl2 at −78 °C to room temperature to give only
cis-(PPh3)2PtCl(h1-CH2CꢀCPh).
Thus, there appear to be two patterns for ligand
addition reactions at metal of [(PPh3)2Pt(h3-CH2-
CCPh)]+. The neutral ligands CO and CNCMe3 (L)
yield the trans isomer of each tautomeric form of
allenyl/propargyl, i.e. [trans-(PPh3)2PtL(h1-C(Ph)ꢁCꢁ
CH2)]+ and [trans-(PPh3)2PtL(h1-CH2CꢀCPh)]+. How-
ever, the halides Br− and Cl− (X−) afford exclusively
(or almost exclusively) the h1-propargyl tautomer as the
cis isomer of (PPh3)2PtX(h1-CH2CꢀCPh). These results
Acknowledgements
This study was supported in part by the National
Science Foundation, The Ohio State University, and
MURST (Rome). P.W.B. thanks Procter and Gamble
Co. for a graduate fellowship.
References
[1] (a) A. Wojcicki, C.E. Shuchart, Coord. Chem. Rev. 65 (1990)
219;
(b) A. Wojcicki, New J. Chem. 18 (1994) 61;
(c) S. Doherty, J.F. Corrigan, A.J. Carty, E. Sappa, Adv.
Organomet. Chem. 37 (1995) 39;
(d) J.-T. Chen, Coord. Chem. Rev. 190–192 (1999) 1143.
[2] (a) C.J. Elsevier, H. Kleijn, K. Ruitenberg, P. Vermeer, J. Chem.
Soc., Chem. Commun. (1983) 1529;
(b) C.J. Elsevier, H. Kleijn, J. Boersma, P. Vermeer,
Organometallics 5 (1986) 716.
[3] J.P. Collman, J.N. Cawse, J.W. Kang, Inorg. Chem. 8 (1969)
2574.
[4] (a) R.-S. Keng, Y.-C. Lin, Organometallics 9 (1990) 289;
(b) T.-W. Tseng, I.-Y. Wu, J.-H. Tsai, Y.-C. Lin, C.-J. Chen,
G.-H. Lee, M.-C. Cheng, Y. Wang, Organometallics 13 (1994)
3963.

116
P.W. Blosser et al. / Inorganica Chimica Acta 320 (2001) 110–116
[5] J. Pu, T.-S. Peng, A.M. Arif, J.A. Gladysz, Organometallics 11
[14] D.D. Perrin, W.L.F. Armarego, D.R. Perrin, Purification of
Laboratory Chemicals, Pergamon, Oxford, 1991.
[15] B.A. Frenz and Associates, Inc., Structure Determination Pack-
age, Enraf–Nonius, Delft, 1985.
(1992) 3232.
[6] A.J. Canty, H. Jin, J.D. Penny, J. Organomet. Chem. 573 (1999)
30.
[7] (a) P.W. Blosser, D.G. Schimpff, J.C. Gallucci, A. Wojcicki,
Organometallics 12 (1993) 1993;
[16] C.E. Shuchart, R.R. Willis, A. Wojcicki, J. Organomet. Chem.
424 (1992) 185.
(b) M.W. Baize, P.W. Blosser, V. Plantevin, D.G. Schimpff, J.C.
Gallucci, A. Wojcicki, Organometallics 15 (1996) 164;
(c) R.R. Willis, M. Calligaris, P. Faleschini, J.C. Gallucci, A.
Wojcicki, J. Organomet. Chem. 593/594 (2000) 465;
(d) P.W. Blosser, J.C. Gallucci, A. Wojcicki, J. Organomet.
Chem. 597 (2000) 125.
[17] J.-L. Roustan, P. Cadiot, C.R. Acad. Sci., Ser. C 268 (1969) 734.
[18] (a) R.-H. Hsu, J.-T. Chen, G.-H. Lee, Y. Wang, Organometallics
16 (1997) 1159;
(b) J.-T. Chen, Y.-K. Chen, J.-B. Chu, G.-H. Lee, Y. Wang,
Organometallics 16 (1997) 1476.
[19] J.M.A. Wouters, R.A. Klein, C.J. Elsevier, L. Ha¨ming, C.H.
Stam, Organometallics 13 (1994) 4586 and references cited
therein.
[20] T.-M. Huang, R.-H. Hsu, C.-S. Yang, J.-T. Chen, G.-H. Lee, Y.
Wang, Organometallics 13 (1994) 3657.
[21] (a) V.G. Andrianov, I.B. Zlotina, M.A. Khomutov, N.E.
Kolobova, Yu.T. Struchkov, Koord. Khim. 4 (1978) 298;
(b) H. Werner, R. Flu¨gel, B. Windmu¨ller, A. Michenfelder, J.
Wolf, Organometallics 14 (1995) 612;
(c) M.A. Esteruelas, A.V. Gomez, A.M. Lopez, J. Modrego, E.
Onate, Organometallics 17 (1998) 5434;
(d) J. Barluenga, A.A. Trabanco, J. Florez, S. Garcia-Granda,
M.A. Llorca, J. Am. Chem. Soc. 120 (1998) 12129.
[22] (a) H. Berke, P. Harter, G. Huttner, L. Zsolnai, Z. Naturforsch.,
Teil B 36 (1981) 929;
[8] (a) S. Ogoshi, Y. Fukunishi, K. Tsutsumi, H. Kurosawa, J.
Chem. Soc., Chem. Commun. (1995) 2485;
(b) S. Ogoshi, Y. Fukunishi, K. Tsutsumi, H. Kurosawa, Inorg.
Chim. Acta 265 (1997) 9.
[9] (a) V.V. Krivykh, E.S. Taits, P.V. Petrovskii, Yu.T. Struchkov,
A.I. Yanovskii, Mendeleev Commun. (1991) 103;
(b) V.V. Krivykh, Organomet. Chem. USSR (Engl. Transl.) 5
(1992) 113; Metallorg. Khim. 5 (1992) 213.
[10] (a) C.P. Casey, C.S. Yi, J. Am. Chem. Soc. 114 (1992) 6597;
(b) C.P. Casey, A.D. Selmeczy, J.R. Nash, C.S. Yi, D.R. Powell,
R.K. Hayashi, J. Am. Chem. Soc. 118 (1996) 6698;
(c) C.P. Casey, J.R. Nash, C.S. Yi, A.D. Selmeczy, S. Chung,
D.R. Powell, R.K. Hayashi, J. Am. Chem. Soc. 120 (1998) 722.
[11] (a) A.-J. Chen, C.-C. Su, F.-Y. Tsai, J.-J. Lee, T.-M. Huang,
C.-S. Yang, G.-H. Lee, Y. Wang, J.-T. Chen, J. Organomet.
Chem. 569 (1998) 39;
(b) N.E. Kolobova, L.L. Ivanov, O.S. Zhvanko, O.M. Khitrova,
A.S. Batsanov, Yu.T. Struchkov, J. Organomet. Chem. 265
(1984) 271;
(c) R. Aumann, B. Jasper, M. Lage, B. Krebs, Chem. Ber. 127
(1994) 127.
(b) Y.-C. Cheng, Y.-K. Chen, T.-M. Huang, C.-I. Yu, G.-H.
Lee, Y. Wang, J.-T. Chen, Organometallics 17 (1998) 2953 and
references cited therein.
[12] (a) H. Kurosawa, S. Ogoshi, Bull. Chem. Soc. Jpn. 71 (1998)
3514;
(b) T. Nishida, S. Ogoshi, K. Tsutsumi, Y. Fukunishi, H.
Kurosawa, Organometallics 19 (2000) 4488.
[13] D.F. Shriver, M.A. Drezdzon, The Manipulation of Air-Sensi-
tive Compounds, Wiley, New York, 2nd edn., 1986.
[23] J.P. Collman, L.S. Hegedus, J.R. Norton, R.G. Finke, Principles
and Applications of Organotransition Metal Chemistry, Univer-
sity Science Books, Mill Valley, CA, 1987, p. 532.
[24] M.N. Ackermann, R.K. Ajmera, H.E. Barnes, J.C. Gallucci, A.
Wojcicki, Organometallics 18 (1999) 787.
.