Regiochemical control of a Pt-promoted alkylation of the phenyl ring

Article abstract of DOI:10.1039/a800603b

The reactivity of cationic Pt^II-phenyl complexes of the type [PtPh(CH₂=CHR)(Phen)]⁺ (R = H or Me) has been investigated. In all cases, insertion of the alkene into the Pt-Ph bond has been observed. The fate of the resulting Pt-CH₂CHRPh (R = H or Me) derivative depends on the experimental conditions. In the presence of donor ligands (e.g. excess olefin, pyridine or triphenylphosphine) the product is stable, while in the absence of them a rapid rearrangement to form Pt-C₆H₄(CHRMe)-2 occurs.

Full text of DOI:10.1039/a800603b

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Regiochemical control of a Pt-promoted alkylation of the phenyl ring
Maria E. Cucciolito, Augusto De Renzi,*,† Ida Orabona, Francesco Ruffo and Diego Tesauro
Dipartimento di Chimica, Università di Napoli ‘Federico II’, via Mezzocannone 4, I-80134 Napoli,
Italy
The reactivity of cationic PtII–phenyl complexes of the type [PtPh(CH ᎐CHR)(phen)]ϩ (R = H or Me) has been
᎐
2
investigated. In all cases, insertion of the alkene into the Pt᎐Ph bond has been observed. The fate of the resulting
Pt᎐CH2CHRPh (R = H or Me) derivative depends on the experimental conditions. In the presence of donor
ligands (e.g. excess olefin, pyridine or triphenylphosphine) the product is stable, while in the absence of them a
rapid rearrangement to form Pt᎐C6H4(CHRMe)-2 occurs.
It has been reported1 by some of us that cationic PtII–aryl com-
N
plexes containing a N,N chelate ligand [e.g. 6-MeC5H3N-2-
CH2
N
Pt
Cl
CH᎐NR (R = Me or Ph)] effectively promote the migratory
᎐
insertion of alkenes into the PtII᎐Caryl σ bond. Two different
metal-bound hydrocarbyl groups are formed, according to the
experimental conditions (Scheme 1). It was observed that the
presence of a bidentate N,N ligand with reduced in-plane
hindrance,2 and/or an excess of alkene, promoted the complete
formation of A. However, no definite conclusion was reached
about the mechanistic pattern of the process. In fact, two reac-
tion paths with different transition states could account for the
formation of A and B, or a unique parent precursor could be
driven differently by the reaction environment.
A
CHR
N
CH2=CHR, Cl–
N
Pt+ NCMe
N
B
N
Pt
Cl
CHR Me
In this paper we report an investigation on the mechanism of
the above reaction. The studies indicate that the co-ordinating
ability of the olefin and of the ancillary ligands as well as the
rates of the exchange processes exert a powerful influence in
determining the overall reaction pattern and the type of the
resulting hydrocarbyl derivative.
Scheme 1
equation (3), R = H, 6 or R = Me, 7] could be isolated and were
fully characterized:
[Pt(CH CHRPh)(CH ᎐CHR)(phen)]BF ϩ KI →
᎐
2
2
4
[Pt(CH CHRPh)I(phen)] ϩ CH ᎐CHR ϩ KBF (3)
᎐
2
2
4
Results and Discussion
The square-planar [PtPhI(phen)] 1 (phen = 1,10-phenanthro-
line) complex was used as a starting material to generate the
reactive cationic PtII species by treatment with AgBF4. The iodo
derivative was preferred to the chloro homologue because of
the faster and quantitative halide removal. By adding at room
temperature solid 1 to a nitromethane solution of an equi-
molar amount of AgBF4 under an olefin (ethene or propene)
atmosphere, immediate dissolution of the complex ensued and
formation of the cis-phenyl–olefin cationic complexes [PtPh-
The reactive intermediates 2 and 3 were characterized using
1H NMR spectroscopy with a stoichiometric amount of olefin
in order to get sharp signals. The two halves of the phen ligand
are not equivalent and the olefin protons couple to 195Pt [e.g. for
2
2, δ(C2H4) 4.85, JPt᎐H 69 Hz]. A slight excess of olefin causes
broadening of the signals and loss of the satellites, while the
unsymmetric pattern is retained for the phen protons. This is
consistent with the occurrence of a fast olefin exchange via an
associative mechanism.3
(CH ᎐CHR)(phen)]BF (R = H, 2 or R = Me, 3) was observed
᎐
2
4
The Markovnikov regiochemistry of propene insertion, i.e.
formation of the Pt᎐CH2CH(Me)Ph fragment, is fully consist-
ent with our previous findings.1 It should be noted that under
similar experimental conditions, the analogous palladium()
complex [PdPh(MeCN)(bipy)]ϩ showed a different behaviour
when treated with propene.4 In fact, initial formation of the
Pd᎐CH(Me)CH2Ph moiety and its subsequent rearrangement
to the Pd᎐CH(Et)Ph group was observed. The change of
regiochemistry on going from Pt to Pd was explained4 in
terms of a stabilizing effect played by the phenyl group on a
Pd-bound carbon.
[equation (1)]. Within 1 h complete transformation of 2 and 3
[PtPhI(phen)] ϩ AgBF ϩ CH ᎐CHR →
᎐
4
2
AgI ϩ [PtPh(CH ᎐CHR)(phen)]BF (1)
᎐
2
4
into the corresponding insertion products [Pt(CH2CHRPh)-
(CH ᎐CHR)(phen)]BF [equation (2), R = H, 4 or R = Me, 5]
᎐
2
4
[PtPh(CH ᎐CHR)(phen)]BF ϩ CH ᎐CHR →
᎐
᎐
2
2
4
[Pt(CH CHRPh)(CH ᎐CHR)(phen)]BF (2)
᎐
2
2
4
Attempts to isolate the cationic cis-phenyl–ethene complex 2
in the solid state were unsuccessful. By adding diethyl ether to a
nitromethane solution of the complex immediately after its
formation, a yellow solid was obtained. This transformed into
a reddish product in spite of careful working up in attempting
1
was observed in the H NMR monitored experiments. More-
over, while attempts to obtain solid 5 failed, complex 4 and
the neutral [Pt(CH2CHRPh)I(phen)] complexes [obtained by
1
isolation in the cold. The H NMR spectrum of this material
showed only the presence of Pt᎐C6H4Et-2 and Pt᎐CHMePh
† E-Mail: derenzi@unina.it
J. Chem. Soc., Dalton Trans., 1998, Pages 1675–1678
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groupings. It should be noted that PtII complexes similar to 2
and 3, but including alkyl instead of aryl groups, have already
been isolated and characterized3 and are stable towards
the insertion migratory process. When a solution of 2 was
allowed to stand at room temperature in the absence of free
olefin, the signals attributable to the η2-complex disappeared
within 1 h but formation of the Pt᎐CH2CH2Ph fragment was
not observed. Instead, a Pt᎐C6H4Et-2 moiety was detected
[equation (4)] and [Pt(C6H4Et-2)(MeCN)(phen)]BF4 8 was
N
N
Pt+
L
+ L
N
[PtPh(CH ᎐CH )(phen)]ϩ → {Pt(C H Et-2)(phen)}ϩ (4)
N
N
᎐
2
2
6
4
N
Pt+
Pt+
N
Pt
N
isolated in high yield after addition of MeCN [equation (5)]. We
{Pt(C6H4Et-2)(phen)}ϩ ϩ MeCN →
[Pt(C6H4Et-2)(MeCN)(phen)]ϩ (5)
X
note that if complex 2 is allowed to stand for a longer time
in solution in the absence of MeCN a slow decomposition
takes place to a brown unidentified material and ethylbenzene.
On the other hand, if 1 equivalent of MeCN is immediately
added to a freshly prepared solution of 2, [Pt(CH2CH2Ph)-
(MeCN)(phen)]BF4 9 is ultimately obtained [equation (6)]
+ MeCN
N
N
Pt+
NCMe
[PtPh(CH ᎐CH )(phen)]ϩ ϩ MeCN →
᎐
2
2
[Pt(CH2CH2Ph)(MeCN)(phen)]ϩ (6)
as the main reaction product and complex 8 forms only in small
amounts.
Scheme 2
Similar results were obtained in the case of the propene
derivative 3 and the formation of the corresponding Pt᎐C6H4-
(CHMe2)-2 moiety was clearly observed in the experiments
performed in the absence of free MeCN. However, the longer
reaction time (ca. 2.5 h) required to reduce substantially the
amount of the starting η2 species and a fast decomposition
process of the isopropylphenyl derivative to isopropylbenzene
prevented the isolation of a definite hydrocarbyl PtII complex
analogous to 8.
case of excess ethene being present. Otherwise, besides 4, an
increasing amount of 9 was detected with time. These data sug-
gest the occurrence of a preliminary ligand exchange step, in
which acetonitrile is slowly substituted by ethene to form 2.‡
Since insertion is faster than substitution, formation of species
X occurs in all cases in the presence of free ethene. Therefore,
according to the better ligand ability of ethene relative to
MeCN, complex 4 is detected as the first reaction product even
though an initial 1:1 ethene–Pt ratio is used. However, owing to
the presence of free MeCN, an equilibrium process occurs
involving 9 (release of ethene) allowing further formation of
4 until the overall reaction to give 4 and 9 is complete. It is
noteworthy that the same final result, i.e. a mixture of 4 and 9,
was obtained by adding MeCN to a freshly prepared solution
of 2 in which no excess ethene was present. In particular, after
30 min only 4 was detected in 50% yield based on Pt.
A suggestion arises by comparing this experiment with that
performed in the absence of MeCN [equation (4)]. In the latter
case, quantitative formation of Pt᎐C6H4Et-2 ensued. This
means that, although (as noted above) acetonitrile does not co-
ordinate to Pt in the early stages of the reaction, it must play an
active role in inhibiting the rearrangement [Pt(CH2CH2Ph)-
(phen)]ϩ → [Pt(C6H4Et-2)(phen)]ϩ. This inhibition would
favor the intervention of unreacted ethene to form 4, stable
towards the rearrangement. Finally, we wish to comment on the
observed preference1 towards the formation of the Pt᎐C6H4Et-
2 moiety in the case when the starting substrate contains an
N,N-chelate ligand which favors the olefin uptake with form-
ation of a five-coordinate adduct. This preference is largely
reduced if the cationic complex [PtRЈ(C2H4)(MeCN)(N,N-
chelate)]ϩ is allowed to stand at a temperature higher than 273
K and/or free olefin is present in solution, and free MeCN also
has an inhibitory effect. This behaviour can be rationalized on
the basis of the existence of the two equilibria (7). In fact, if the
The ensemble of results suggests that the Pt᎐C6H4(CHRMe)-
2 group derives from a rearrangement of the Pt᎐CH2CHRPh
fragment prompted by the absence of ligands able to fill the co-
ordinative unsaturation following the ‘usual’ migratory inser-
tion process (see species X in Scheme 2). Actually, the possibil-
ity of such a rearrangement was already presented in a previous
work.1 However, it looked to be only speculative, since the
experimental conditions used did not provide clear evidence.
In keeping with the above hypothesis, removal of iodine from
the neutral [Pt(CH2CHRPh)I(phen)] complexes (6 or 7) in the
absence of potential ligands was followed by rapid formation of
Pt᎐C6H4(CHRMe)-2 groups. It should be noted that if halogen
removal from 6 was performed in the presence of MeCN, a
mixture of 8 and 9 was obtained. On the other hand, only
[Pt(CH2CH2Ph)(L)(phen)]BF4 species (4, 10 or 11; L = ethene,
pyridine or triphenylphosphine) were isolated in the presence of
L. Moreover, an analysis of these results discloses some signifi-
cant differences with those previously obtained1 by reacting the
cationic substrates [PtRЈ(MeCN)(N,N-chelate)]ϩ [RЈ = C6H4-
(OMe)-4] with the same olefins used here, i.e. ethene and
propene. In the former case a markedly longer reaction time
(up to 48 h) was necessary to complete the insertion–
rearrangement process. Furthermore, only crowded N,N lig-
ands afforded the Pt᎐C6H4(CHRMe)-2 moiety, while ligands
similar to phen gave rise only to the corresponding Pt᎐CH2-
CHRRЈ derivatives.
In order to rationalize these results, the reaction of [PtPh-
(MeCN)(phen)]BF4 12 with ethene was reinvestigated (Scheme
3). A markedly slow reaction was observed and the first detect-
able product was 4, irrespective of the C2H4–complex ratio. A
nearly 50% conversion was evaluated after 5 h, and the reaction
was complete after 24 h with quantitative formation of 4, in the
‡ It should be noted that when [PtR(MeCN)(N,N-chelate)]ϩ (R = alkyl)
species are allowed to stand at room temperature in an ethene-saturated
solution, several hours are required to obtain a 50% substitution of
MeCN for the olefin with formation of the corresponding species
[PtR(CH2᎐᎐CH2)(N,N-chelate)]ϩ.
1676
J. Chem. Soc., Dalton Trans., 1998, Pages 1675–1678

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N
N
N
fast
slow
Pt+
N
Pt+ NCMe
N
Pt
+
MeCN
N
2
X
12
C2H4 fast
N
N
slow
Pt+
N
Pt+
N
C2H4
+
MeCN
4
9
Scheme 3
[PtRЈ(C2H4)(N,N-chelate)]ϩ ϩ MeCN
II (e.g. 2)
step are clearly favored, while the rearrangement is hindered
by a competitive co-ordination to the promoting metal center.
The same inhibitory effect is observed if, operating with a
stoichiometric amount of olefin, other σ-donor species are
present in solution. Actually, the reported results give a further
example of the peculiar ability of an unsaturated metal center
in promoting unusual reaction paths.5
[PtRЈ(C2H4)(MeCN)(N,N-chelate)]ϩ
I
[PtRЈ(MeCN)(N,N-chelate)]ϩ ϩ C2H4 (7)
III (e.g. 12)
steric features of the N,N ligand lead to a fair stabilization of
the species I, it can be inferred that both the dissociative equi-
libria are largely displaced towards the five-co-ordinate adduct.
Therefore, at low temperature (<273 K) and in the absence
of added MeCN and/or olefin, very small concentrations of the
dissociation products are present in solution and the migratory
insertion on the reactive species II can be followed by the
intramolecular rearrangement to Pt(C6H4Et-2) prior to the
intermolecular addition of released MeCN or C2H4 stabilizing
the Pt(CH2CH2Ph) fragment. On raising the temperature, the
increased dissociation of I affords a concentration of released
ligands sufficient to cause a fair competition between the two
processes, so that the preference towards the formation of a
final Pt(C6H4Et-2) containing product decreases. The same
effect is observed when an excess of C2H4 is added to the
reaction medium, as it does not disfavor the formation of II
and its evolution to Pt(CH2CH2Ph), but inhibits the subsequent
rearrangement to Pt(C6H4Et-2). On the other hand, a large
excess of MeCN hinders the whole process shifting the equi-
libria far from II. On this basis, if species I contains an N,N
ligand with moderate or quite poor five-co-ordination stabil-
izing properties, dissociation in solution to four-co-ordinate
II and III is largely observed, irrespective of the temperature
and of the presence of excess MeCN and/or olefin. As a
consequence, only complexes containing the Pt(CH2CH2Ph)
moiety are obtained.
Experimental
Proton NMR spectra were recorded at 250 or 200 MHz on a
Bruker AC-250 or a Varian XL-200 spectrometer, respectively.
The spectra were recorded at 298 K in deuteriochloroform or
deuterionitromethane. Proton NMR chemical shifts are
reported in δ (ppm) relative to the solvent (CDCl3, 7.26 ppm;
CHD2NO2, 4.33 ppm), the abbreviation app defines apparent.
The complex [PtPhCl(cod)] (cod = cycloocta-1,5-diene) was
prepared according to literature methods.6 Solvents and
reagents were of AnalaR grade and were used without further
purification.
Preparations
[PtPhCl(phen)]. A solution of phen (0.18 g, 1.0 mmol) in
the minimum amount of methylene chloride was added at
room temperature with stirring to a solution of [PtPhCl(cod)]
(0.42 g, 1.0 mmol) in methylene chloride (10 ml). After 20 h
of stirring the solid was collected and washed with methylene
chloride (2 × 3 ml) and dried under vacuum (85–90% yield).
The compound was too insoluble in common organic solvents
for recording an NMR spectrum (Found: C, 44.28; H, 2.58; N,
5.80. Calc. for C18H13ClN2Pt: C, 44.32; H, 2.69; N, 5.74%).
[PtPh(MeCN)(phen)]BF4 12. A solution of AgBF4 (0.20 g,
1.0 mmol) in acetonitrile (10 ml) was added at room temper-
ature to a suspension of [PtPhCl(phen)] (0.49 g, 1.0 mmol) in
anhydrous methylene chloride (25 ml) under a nitrogen atmos-
phere. After 24 h of stirring AgCl was removed by filtration
and the solvent of the filtrate was evaporated to dryness. The
product was obtained as a yellow glassy solid in nearly quanti-
Conclusion
Two observations stemming from the above study deserve
particular comment: (i) the metal-assisted olefin–hydrocarbyl
migratory insertion process requires that these two groups are
co-ordinated to the same metal center in adjacent positions.
However, these intermediates are generally too labile to be
detected or too inert to be reactive. The studied reaction system
has offered the unique opportunity of identifying a cis-PtII–
olefin–phenyl complex whose kinetic stability allows to gain
unequivocal evidence both of its presence and of its subsequent
transformation. (ii) The conversion of a cationic PtII᎐RЈ sub-
strate to a cationic PtII᎐RЈ(R)-2 (RЈ = aryl, R = alkyl) product
by alkene addition is a multi-step process which is affected in
two opposite ways by an excess of olefin. The co-ordination of
the alkene to the metal and the subsequent migratory-insertion
1
tative yield. H NMR (200 MHz, CD3NO2): δ 9.25 [1 H, d,
3J(HH) 5, H2 of phen], 8.90 (2 H, dd, H4, H7 of phen), 8.70 [1
H, d, 3J(PtH) 60, 3J(HH) 5, H9 of phen], 8.20 (1 H, dd, H3 or H8
of phen), 8.18 (2 H, s, H5, H6 of phen), 7.85 (1 H, dd, H8 or H3 of
phen), 7.50 [2 H, d, J(PtH) 50, J(HH) 8, H2, H6 of Ph], 7.2
(3 H, m, H3, H4, H5 of Ph), 2.73 (3 H, s, MeCN) (Found: C,
41.21; H, 2.84; N, 7.30. Calc. for C20H16BF4N3Pt: C, 41.40; H,
2.78; N, 7.24%).
3
3
[PtPhI(phen)] 1. A saturated solution of KI in water (4 ml)
was added to [PtPh(MeCN)(phen)]BF4 (0.49 g, 1.0 mmol) in
nitromethane (4 ml). After 5 min of stirring the precipitated
J. Chem. Soc., Dalton Trans., 1998, Pages 1675–1678
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orange product was collected and washed with acetone (3 × 2
ml), chloroform (2 × 2 mL) and dried under vacuum (85–90%
yield). The compound was too insoluble in common organic
solvents for recording an NMR spectrum (Found: C, 37.40; H,
2.18; N, 4.91. Calc. for C18H13IN2Pt; C, 37.32; H, 2.26; N,
4.84%).
CH2Me], 2.73 (3 H, s, MeCN), 1.22 (3 H, t, CH2Me) (Found:
C, 43.52; H, 3.26; N, 7.03. Calc. for C22H20BF4N3Pt: C, 43.44;
H, 3.31; N, 6.91%).
Monitoring of the reactions through 1H NMR spectroscopy
A solution of AgBF4 (0.007 g, 0.036 mmol) in deuterio-
nitromethane (ca. 1 ml) containing a known amount of the
appropriate reagent (acetonitrile, propene, ethene, pyridine or
triphenylphosphine) was added to [PtRI(phen)] (R = Ph or
CH2CH2Ph) (0.034 mmol). The mixture was filtered through
Celite to remove AgI and the clear solution transferred into an
NMR tube. Spectra were recorded until no more chemical
changes were detected. Selected 1H NMR (200 MHz, CD3-
NO2): 2 δ 9.0 (3 H, m, H2, H4, H7 of phen), 8.81 [1 H, d, 3J(HH)
5, H9 of phen], 8.30 (2 H, s, H5, H6 of phen), 8.22 (1 H, dd, H3
or H8 of phen), 8.10 (1 H, dd, H8 or H3 of phen), 7.49 [2 H, d,
3J(PtH) 40, 3J(HH) 8, H2, H6 of Ph], 7.20 (3 H, m, H3, H4, H5
of Ph), 4.80 [4 H, s, 2J(PtH) 68, C2H4]; 3 δ 9.0 (4 H, m, H2, H4,
H7, H9 of phen), 8.28 (2 H, s, H5, H6 of phen), 8.26 (1 H, dd, H3
or H8 of phen), 8.00 (1 H, dd, H8 or H3 of phen), 7.5 (2 H, m,
H2, H6 of Ph), 7.20 (3 H, m, H3, H4, H5 of Ph), 5.72 [1 H, app
qnt, 2J(PtH) 76, 3J(HH) 7, CH2᎐᎐CHMe], 4.92 [1 H, d, 2J(PtH)
[Pt(CH2CH2Ph)(phen)(C2H4)]BF4 4. Solid [PtPhI(phen)]
(0.58 g, 1.0 mmol) was added to a solution of AgBF4 (0.20 g,
1.0 mmol) in dry nitromethane (6 ml) under an ethene atmos-
phere at 273 K. After 5 min of stirring AgI was removed by
filtration through Celite under an ethene atmosphere and the
solution was allowed to stand at room temperature for 24 h.
The volume of the solution was reduced to 2 ml under
vacuum. Yellow crystals of product were obtained by careful
1
addition of diethyl ether (70–75% yield). H NMR (200 MHz,
3
3
CD3NO2): δ 9.30 [1 H, d, J(PtH) 50, J(HH) 5, H2 of phen],
9.05 [1 H, d, 3J(HH) 9, H4 or H7 of phen], 8.90 [1 H, d, 3J(HH)
9, H7 or H4 of phen], 8.72 [1 H, d, 3J(HH) 5, H9 of phen], 8.30
(1 H, dd, H3 or H8 of phen), 8.25 (2 H, s, H5, H6 of phen), 8.15
(1 H, dd, H8 or H3 of phen), 7.39 [2 H, d, 3J(HH) 7, H2, H6 of
Ph], 7.25 (3 H, m, H3, H4, H5 of Ph), 4.55 (4 H, br, C2H4), 2.89
3
2
[2 H, t, J(HH) 7.5, Pt᎐CH2CH2Ph], 1.62 [2 H, t, J(PtH) 75,
Pt᎐CH2CH2Ph] (Found: C, 44.55; H, 3.42; N, 4.60. Calc. for
C22H21BF4N2Pt: C, 44.39; H, 3.56; N, 4.71%).
76, 3J(HH) 7, CHH᎐CHMe], 4.60 [1 H, d, 2J(PtH) 64, 3J(HH)
᎐
3
14, CHH᎐CHMe], 1.86 [3 H, d, J(PtH) 60, CH ᎐CHMe]; 5 δ
᎐
᎐
2
9.28 [1 H, d, J(PtH) 45, J(HH) 5, H2 of phen], 9.00 [1 H, d,
3J(HH) 8, H4 or H7 of phen], 8.90 [2 H, m, H7 or H4, H9 of
phen], 8.30 (2 H, s, H5, H6 of phen), 8.15 (2 H, m, H3, H8 of
phen), 7.40 [2 H, d, 3J(HH) 8, H2, H6 of Ph], 7.20 (3 H, m, H3,
H4, H5 of Ph), 5.80 (1 H, br, CH ᎐CHMe), 4.75 (2 H, br,
3
3
[Pt(CH2CHRPh)I(phen)] R ؍ H, 6 or R ؍ Me, 7. A satur-
ated solution of KI in water (10 ml) was vigorously shaken
with a solution of [Pt(phen)(CH2CHRPh)(ethene)]BF4 (1.0
mmol) in nitromethane (5 ml) and chloroform (10 ml). The
organic phase was separated and the water phase was washed
with chloroform (2 × 10 ml). The combined organic phases
were dried over sodium sulfate and the solvents removed under
vacuum to afford the product as an orange solid (80%).
1H NMR (250 MHz, CDCl3): 6 δ 10.30 [1 H, d, 3J(HH) 6, H2 of
᎐
2
CH ᎐CHMe), 3.11 [1 H, app sxt, 3J(HH) 7, Pt᎐CH2CH-
᎐
2
(Me)Ph], 1.90–1.60 [2 H, m, Pt᎐CH2CH(Me)Ph], 1.80 [3 H, d,
3J(HH) 7, Pt᎐CH2CH(Me)Ph], 1.55 [3 H, d, 3J(PtH) 40,
3J(HH) 8, CH ᎐CHMe]; 9 δ 9.21 [1 H, d, 3J(PtH) 48, 3J(HH) 5,
᎐
2
H2 of phen], 9.05 [1 H, d, 3J(HH) 5, H9 of phen], 8.83 (2 H, dd,
H4, H7 of phen), 8.14 (2 H, s, H5, H6 of phen), 8.10 (2 H, m, H3,
H8 of phen), 7.49 [2 H, d, 3J(HH) 6, H2, H6 of Ph], 7.38 (2 H, t,
3
3
phen], 9.28 [1 H, d, J(PtH) 60, J(HH) 6, H9 of phen], 8.72
[1 H, d, 3J(HH) 10, H4 or H7 of phen], 8.51 [1 H, d, 3J(HH) 10,
H7 or H4 of phen], 7.99 (2 H, s, H5, H6 of phen), 7.85 (2 H, m,
3
H3, H5 of Ph), 7.21 (1 H, t, H4 of Ph), 2.84 [2 H, t, J(HH) 5,
Pt᎐CH2CH2Ph], 2.77 (3 H, s, MeCN), 2.38 [2 H, t, 2J(PtH) 80,
PtCH2CH2]; 10 δ 9.41 [1 H, d, 3J(HH) 7, H2 of phen], 2.75 [2 H,
t, 3J(HH) 7, Pt᎐CH2CH2Ph], 2.18 [2 H, t, 2J(PtH) 65, Pt᎐
3
H3, H8 of phen), 7.40 [2 H, d, J(HH) 7, H2, H6 of Ph], 7.19
3
(3 H, m, H3, H4, H5 of Ph), 2.88 [2 H, t, J(HH) 7.5, Pt᎐CH2-
2
CH2Ph], 2.62 [2 H, t, J(PtH) 80, Pt᎐CH2CH2Ph]; 7 δ 10.33
3
CH2CH2Ph]; 11 δ 9.52 [1 H, d, J(HH) 7, H2 of phen], 2.55
[1 H, d, 3J(HH) 5, H2 of phen], 9.17 [1 H, d, 3J(PtH) 60, 3J(HH)
5, H9 of phen], 8.67 [1 H, d, 3J(HH) 7.5, H4 or H7 of phen], 8.52
[1 H, d, 3J(HH) 7.5, H7 or H4 of phen], 7.95 (2 H, s, H5, H6 of
phen), 7.90 (1 H, m, H3 or H8 of phen), 7.73 (1 H, m, H8 or H3
of phen), 7.49 [2 H, d, 3J(HH) 7.5, H2, H6 of Ph], 7.20 (3 H, m,
H3, H4, H5 of Ph), 3.12 [2 H, m, Pt᎐CHHCH(Me)Ph], 2.26
[1 H, d, 2J(PtH) 95, 3J(HH) 5, Pt᎐CHHCH(Me)Ph], 1.55 [3 H,
d, 3J(HH) 7.5, Me] (Found: C, 39.67; H, 2.91; N, 4.40. Calc. for
C20H17IN2Pt 6: C, 39.55; H, 2.82; N, 4.61. Found: C, 40.57;
H, 2.98; N, 4.64. Calc. for C21H19IN2Pt 7: C, 40.59; H, 3.08;
N, 4.51%).
3
2
[2 H, t, J(HH) 7, Pt᎐CH2CH2Ph], 1.80 [2 H, t, J(PtH) 63,
Pt᎐CH2CH2Ph].
Acknowledgements
We thank the Consiglio Nazionale delle Ricerche and the
Ministero dell’Università e della Ricerca Scientifica e Tecnolo-
gica for financial support, the Centro Interdipartimentale di
Metodologie Chimico-Fisiche, Università ‘Federico II’, for
NMR spectroscopy facilities.
References
[Pt(C6H4Et-2)(MeCN)(phen)]BF4 8. Solid [PtPhI(phen)]
(0.58 g, 1.0 mmol) was added to a solution of AgBF4 (0.20 g,
1.0 mmol) in dry nitromethane (6 ml) containing ethene (ca.
1 mmol). After 5 min of stirring AgI was removed by filtration
through Celite and the solution was stirred at room temperature
for 1 h. Acetonitrile (0.041 g, 1.0 mmol) was added to the solu-
tion. After 1 h yellow crystals of 8 were obtained by careful
addition of diethyl ether (85% yield). 1H NMR (200 MHz,
1 V. De Felice, A. De Renzi, D. Tesauro and A. Vitagliano, Organo-
metallics, 1992, 11, 3669.
2 V. G. Albano, G. Natile and A. Panunzi, Coord. Chem. Rev., 1994,
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3 M. Fusto, F. Giordano, I. Orabona, A. Panunzi and F. Ruffo, Organo-
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4 V. De Felice, M. E. Cucciolito, A. De Renzi, F. Ruffo and D. Tesauro,
J. Organomet. Chem., 1995, 493, 1.
3
CD3NO2): δ 9.33 [1 H, d, J(HH) 5, H2 of phen], 8.97 [1 H, d,
5 See, for example, M. W. Holtcamp, J. A. Labinger and J. E. Bercaw,
J. Am. Chem. Soc., 1997, 119, 848.
6 H. C. Clark and L. E. Manzer, J. Organomet. Chem., 1973, 59, 411.
3J(HH) 8, H4 or H7 of phen], 8.86 [1 H, d, 3J(HH) 8, H7 or H4
of phen], 8.40 [1 H, d, 3J(HH) 5, H9 of phen], 8.20 (2 H, m, H5,
H6 of phen), 8.10 (1 H, dd, H3 or H8 of phen), 7.79 (1 H, dd, H8
or H3 of phen), 7.49 [1 H, d, 3J(PtH) 40, 3J(HH) 7.5, H6 of Ph],
7.20 (3 H, m, H3, H4, H5 of Ph), 3.02 [2 H, q, 3J(HH) 8,
Received 22nd January 1998; Paper 8/00603B
1678
J. Chem. Soc., Dalton Trans., 1998, Pages 1675–1678