Chemical properties of cationic phenylplatinum(II) complexes with a 2,2′-bipyridine ligand. Insertion of CO and allene into the Pt-C bond and oxidative addition of MeI

Article abstract of DOI:10.1021/om0109105

[PtPh(bpy)(solvent)]BF₄ (1-MeCN, solvent = MeCN; 1-acetone, solvent = acetone) are prepared from the reaction of HBF₄ with PtPh₂(bpy) or from the reaction of AgBF₄ with PtI(Ph)(bpy). The MeCN ligand of 1-MeCN in a CD₃CN solution undergoes exchange with the solvent in 12 h at room temperature. The coordinated solvent of 1-acetone is replaced with acetone-d₆ much more rapidly. 1-acetone reacts easily with H₂O and CO to form 1-OH₂ and 1-CO, respectively. The reaction of phenylallene with 1-acetone produces the (π-allyl)-platinum complex [Pt(η³-CH₂CPhCHPh)(bpy)]BF₄ (2) as a mixture of syn and anti isomers. One of the isomers, 2-syn, was isolated by recrystallization of the products and characterized by X-ray crystallography and ¹H NMR spectroscopy. The complex reacts with CO (1 atm) at room temperature to form a mixture of [Pt((Z)-CH₂CPh=CHPh)(bpy)(CO)]BF₄ (3-Z) and [Pt-((E)-CH₂CPh=CHPh)(bpy)(CO)]BF₄ (3-E). The ratio of 3-Z to 3-E decreases gradually during the reaction to afford an equilibrium mixture ([3-Z]:[3-E] = 35:65) after 26 min. First-order rate constants of the reaction under CO and under argon are similar to each other, indicating that the isomerization occurs via a pentacoordinate intermediate with carbonyl and π-allyl ligands bonded to the Pt center. 1-MeCN reacts with Mel at 50 °C to produce a mixture of two isomeric cationic Pt(IV) complexes after 9 days. X-ray crystallography of one of the products, [PtI(Me)(Ph)(NCMe)(bpy)]BF₄ (4), revealed an octahedral structure having the methyl, iodo, and bipyridine ligands in the same coordination plane.

Full text of DOI:10.1021/om0109105

2088
Organometallics 2002, 21, 2088-2094
Ch em ica l P r op er ties of Ca tion ic P h en ylp la tin u m (II)
Com p lexes w ith a 2,2′-Bip yr id in e Liga n d . In ser tion of CO
a n d Allen e in to th e P t-C Bon d a n d Oxid a tive Ad d ition
of MeI
Takeyoshi Yagyu, Yuji Suzaki, and Kohtaro Osakada*
Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, J apan
Received October 18, 2001
[PtPh(bpy)(solvent)]BF4 (1-MeCN, solvent ) MeCN; 1-a ceton e, solvent ) acetone) are
prepared from the reaction of HBF4 with PtPh2(bpy) or from the reaction of AgBF4 with
PtI(Ph)(bpy). The MeCN ligand of 1-MeCN in a CD3CN solution undergoes exchange with
the solvent in 12 h at room temperature. The coordinated solvent of 1-a ceton e is replaced
with acetone-d6 much more rapidly. 1-a ceton e reacts easily with H2O and CO to form 1-OH2
and 1-CO, respectively. The reaction of phenylallene with 1-a ceton e produces the (π-allyl)-
platinum complex [Pt(η3-CH2CPhCHPh)(bpy)]BF4 (2) as a mixture of syn and anti isomers.
One of the isomers, 2-syn , was isolated by recrystallization of the products and characterized
1
by X-ray crystallography and H NMR spectroscopy. The complex reacts with CO (1 atm) at
room temperature to form a mixture of [Pt((Z)-CH2CPhdCHPh)(bpy)(CO)]BF4 (3-Z) and [Pt-
((E)-CH2CPhdCHPh)(bpy)(CO)]BF4 (3-E). The ratio of 3-Z to 3-E decreases gradually during
the reaction to afford an equilibrium mixture ([3-Z]:[3-E] ) 35:65) after 26 min. First-order
rate constants of the reaction under CO and under argon are similar to each other, indicating
that the isomerization occurs via a pentacoordinate intermediate with carbonyl and π-allyl
ligands bonded to the Pt center. 1-MeCN reacts with MeI at 50 °C to produce a mixture of
two isomeric cationic Pt(IV) complexes after 9 days. X-ray crystallography of one of the
products, [PtI(Me)(Ph)(NCMe)(bpy)]BF4 (4), revealed an octahedral structure having the
methyl, iodo, and bipyridine ligands in the same coordination plane.
In tr od u ction
reported that the cationic arylpalladium complexes with
a labile THF or acetone ligand undergo facile intermo-
lecular coupling of the aryl ligands to afford biaryl or
insertion of unsaturated molecules such as alkyne and
allene into the Pd-aryl bond.6 The reactivity of the
cationic Pd-MeCN complexes toward the above reac-
tions is lower than the complexes with acetone or THF
ligand. Comparison of the chemical properties of cationic
arylplatinum complexes with those of the Pd complexes
is of interest because the Pt-C bonds are more stable
than the Pd-C bonds of similar square-planar com-
plexes and because the arylplatinum complexes are
suitable for elucidating the mechanism of their reac-
tions. De Felice et al. reported the preparation of [PtAr-
Cationic methylplatinum(II) complexes with auxiliary
nitrogen ligands undergo facile C-H bond activation of
alkanes and insertion of alkenes into the Pt-Me bond,
which is often related to activation and functionalization
of methane promoted by Pt complexes and by related
Pd complexes.1,2 In the past decade, analogous cationic
arylplatinum(II) complexes having chelating diimine
ligands, [PtAr(L2)(solvent)]+ (L2 ) diimine ligand), have
attracted significant attention due to their unique
chemical properties, such as facile insertion of unsatur-
ated molecules into the Pt-Ar bond.3-5 Recently, we
(1) Recent reviews on cationic organoplatinum complexes: (a)
Rendina, L. M.; Puddephatt, R. J . Chem. Rev. 1997, 97, 1735. (b) Stahl,
S. S.; Labinger, J . A.; Bercaw, J . E. Angew. Chem., Int. Ed. 1998, 37,
2180.
(3) (a) Sanchez, A.; Castellari, C.; Panunzi, A.: Vitagliano, A.; De
Felice, V. J . Organomet. Chem. 1990, 388, 243. (b) De Felice, V.; De
Renzi, A.; Tesauro, D.; Vitagliano, A. Organometallics 1992, 11, 3669.
(c) De Felice, V.; Cucciolito, M. E.; De Renzi, A.; Ruffo, F.; Tesauro, D.
J . Organomet. Chem. 1995, 493, 1. (d) De Felice, V.; De Renzi, A.;
Ferrara, M. L.; Panunzi, A. J . Organomet. Chem. 1996, 513, 97.
(4) (a) Heiberg, H.; J ohansson, L.; Gropen, O.; Ryan, O. V.; Swang,
O.; Tilset, M. J . Am. Chem. Soc. 2000, 122, 10831. (b) J ohansson, L.;
Tilset, M.; Labinger, J . A.; Bercaw, J . E. J . Am. Chem. Soc. 2000, 122,
10846.
(5) Earlier reports of cationic arylplatinum complexes: Grove, D.
M.; van Koten, G.; Louwen, J . N.; Noltes, J . G.; Spek, A. L.; Ubbels, J .
C. J . Am. Chem. Soc. 1982, 104, 6609. Terheijden, J .; van Koten, G.;
Vinke, I. C.; Spek, A. L. J . Am. Chem. Soc. 1985, 107, 2891. Ortiz, J .
V.; Havias, Z.; Hoffmann, R. Helv. Chim. Acta 1984, 67, 1.
(6) Yagyu, T.; Hamada, M.; Osakada, K.; Yamamoto, T. Organome-
tallics 2001, 20, 1087.
(2) Current references of cationic methylplatinum(II) complexes with
auxiliary nitrogen ligands: (a) Cucciolito, M. E.; de Felice, V.; Orabona,
I.; Ruffo, F. J . Chem. Soc., Dalton Trans. 1997, 1351. (b) Ganis, P.;
Orabona, I.; Ruffo, F.; Vitagliano, A. Organometallics 1998, 17, 2646.
(c) J ohansson, L.; Ryan, O. B.; Rømming, C.; Tilset, M. Organometallics
1998, 17, 3957. (d) Periana, R. A.; Taube, D. J .; Gamble, S.; Taube,
H.; Satoh, T.; Fujii, H. Science 1998, 280, 560. (e) Reinartz, S.; White,
P. S.; Brookhart, M.; Templeton, J . L. Organometallics 2000, 19, 3854.
(f) Fang, X.; Scott, B. L.; Watkin, J . G.; Kubas, G. J . Organometallics
2000, 19, 4193. (g) Bayler, A.; Canty, A. J .; Edwards, P. G.; Skelton,
B. W.; White, A. H. J . Chem. Soc., Dalton Trans. 2000, 3325. (h)
J ohansson, L.; Tilset, M. J . Am. Chem. Soc. 2001, 123, 739. (i)
J ohansson, L.; Ryan, O. B.; Rømming, C.; Tilset, M. J . Am. Chem. Soc.
2001, 123, 6579. (j) Madine, J . W.; Wang, X.; Widenhoefer, R. A. Org.
Lett. 2001, 3, 385, 1591.
10.1021/om0109105 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 04/11/2002

Phenylplatinum(II) Complexes with 2,2′-Bipyridine
Organometallics, Vol. 21, No. 10, 2002 2089
(L2)(NCMe)]+ (Ar ) C6H4OMe-4; L2 ) 2,9-dimeth-
ylphenanthroline, phenanthroline) and their reaction
with CO to cause insertion of CO into the Pt-Ar bond
under mild conditions and the reaction with 1,1-di-
methylallene to afford a (π-allyl)platinum complex.3c,d,7
In this paper, we report preparation of the cationic
phenylplatinum complex with bipyridine and reactivity
of the complex, which differs depending on the solvent
coordinated to the metal center. The reaction of allene
with the complex to form the (π-allyl)platinum complex
and its further reaction with CO are also mentioned.
1-a ceton e in acetone-d6. The 1H NMR signal of the
coordinated solvent of 1-MeCN in CD3CN appears at δ
2.52 flanked by 195Pt satellite signals (J (PtH) ) 14 Hz),
whose position is distinguished unambiguously from
CHD2CN contained as an impurity in the solvent (δ
1.93; free CH3CN δ 1.95). The peak position and the
coupling constants are similar to those of cationic Pt
complexes with a NCMe ligand.8 The gradual intensity
decrease of the signal of the coordinated MeCN and
concomitant growth of the peak at δ 1.95 indicates
exchange of the coordinated and uncoordinated MeCN
molecules. The spectroscopic change is completed in 12
h at room temperature. On the other hand, 1-a ceton e
in acetone-d6 exhibits a single solvent signal at δ 2.08,
which suggests rapid exchange of the coordinated and
free solvents. Evaporation of a part of acetone from the
solution of 1-a ceton e under vacuum followed by addi-
tion of Et2O led to crystallization of the cationic phenyl-
platinum aqua complex [PtPh(bpy)(H2O)]BF4 (1- OH2),
which was probably formed via exchange of the coordi-
nated solvent with water contained in the solution.
[PtPh(D2O)(bpy)]BF4 (1-OD2) was prepared also from
the reaction with D2O in acetone-d6 and showed NMR
signals of the aromatic hydrogens at positions different
from those of 1-a ceton e.
Resu lts a n d Discu ssion
P r ep a r a tion of Ca tion ic P h en ylp la tin u m Com -
p lexes w ith a Bip yr id in e Liga n d . The cationic phen-
ylplatinum complex [PtPh(bpy)(NCMe)]BF4 (1-MeCN)
is prepared from an equimolar reaction of HBF4 with
PtPh2(bpy) in MeCN (eq 1) or the reaction of AgBF4 with
PtI(Ph)(bpy) in MeCN (eq 2). The reaction of AgBF4 with
The introduction of carbon monoxide (1 atm) to
solutions of 1-MeCN and of 1-a ceton e leads to the
formation of the cationic carbonyl complex [PtPh(bpy)-
(CO)]BF4 (1-CO), as shown in eq 3. The complete
PtI(Ph)(bpy) in acetone produces [PtPh(bpy)(acetone)]-
BF4 (1-a ceton e) as a colorless solid. Previously, we
reported that the reaction of AgBF4 with PdI(Ph)(bpy)
in acetone led to formation of the biphenyl species via
the initial formation of the cationic palladium complex
[PdPh(bpy)(acetone)]BF4, which was not sufficiently
stable to be isolated or fully characterized but, rather,
underwent bimolecular coupling of the phenyl ligand.
The complex 1-a ceton e, however, is stable in acetone
solution for 24 h at room temperature. The complexes
1-MeCN and 1-a ceton e were characterized by 1H NMR
spectroscopy, although the low solubility of the com-
plexes in organic solvents prevented detailed 13C NMR
analyses. 1H NMR signals of ortho phenyl hydrogens of
1-MeCN and 1-a ceton e are observed at δ 7.35 (J (PtH)
) 39 Hz) and δ 7.30 (J (PtH) ) 33 Hz), respectively. Two
pyridyl groups of the bipyridine ligand are observed in
the 1H NMR spectra of 1-MeCN in CD3CN and of
substitution of MeCN of 1-MeCN with CO requires 7
days, while 1-a ceton e undergoes similar ligand ex-
change within 3 h. 1-CO is sufficiently stable to be
1
characterized by H NMR spectroscopy and elemental
analyses. The NMR signals are located at reasonable
positions; the ortho hydrogen signal at δ 7.46 is ac-
companied by 195Pt satellite signals (J (PtH) ) 32 Hz).
The IR spectrum exhibits a characteristic band due to
the carbonyl ligand (ν(CO) ) 2120 cm-1). The reaction
under CO (1 atm) does not cause insertion of CO into
the Pt-Ph bond. This is in contrast with the previous
results that PtAr(Cl)(CO)(L2) (L2 ) 2,9-dimethylphenan-
throline) with a labile pentacoordinated metal center
reacts with CO to cause facile insertion of CO into the
Pt-Ar bond, affording the aroylplatinum(II) complex.3d
(8) [PtCl(NH3)2(NCMe)]+ showed the 1H NMR signal of the MeCN
ligand at δ 2.53 with 4J (PtH) ) 12.7 Hz (Erxleben, A.; Mutikinen, I.;
Lippert, B. J . Chem. Soc., Dalton Trans. 1994, 3667). The coupling
constants of similar complexes are in the range 10.4-14.4 Hz. See also
ref 2.
(7) For analogous reaction of Pt-phosphine complexes, see: Chish-
olm, M. H.; J ohns, W. S. Inorg. Chem. 1975, 14, 1189.

2090 Organometallics, Vol. 21, No. 10, 2002
Yagyu et al.
The reaction of CO with 1-MeCN at higher pressure
(30 atm) produces a mixture of 1-CO and [Pt(COPh)-
(bpy)(CO)]BF4. The mixture shows IR peaks at 2066 and
1647 cm-1 of the carbonyl and benzoyl ligands of the
latter complex in addition to the peaks of 1-CO. Isola-
tion of the benzoylplatinum complex, produced via CO
insertion into the Pt-Ph bond, was not possible, due to
rapid decarbonylation of it during purification. Exposure
of the above mixture of the complexes to argon causes
regeneration of 1-CO very quickly at room temperature.
The reaction is much faster than the decarbonylation
of cationic trans-aroylplatinum(II) complexes with two
monodentate phosphine ligands9 and that of pentaco-
ordinated PtCl(COAr)(CO)(L2) (L2 ) 2,9-dimethylphenan-
throline).3
F igu r e 1. ORTEP drawing of 2-syn (30% probability).
Selected bond lengths (Å) and angles (deg): Pt1-N1 )
2.10(2), Pt1-N2 ) 2.09(2), Pt1-C1 ) 2.12(2), Pt1-C2 )
2.07(7), Pt1-C3 ) 2.13(2), C1-C2 ) 1.45(3), C2-C3 )
1.47(3); N1-Pt1-N2 ) 78.6(8), N1-Pt1-C1 ) 109(1), N1-
Pt1-C2 ) 173.7(9), N1-Pt1-C3 ) 106.9(9), N2-Pt1-C1
) 109(1), N2-Pt1-C2 ) 137.8(9), N2-Pt1-C3 ) 170.2-
(4), C1-Pt1-C3 ) 69.8(9).
In ser tion of Allen e in to th e P t -C Bon d . The
insertion of allene into the Pd-Me bond was studied in
detail.10,11 Previously, we reported preparation of a (π-
allyl)palladium complex from the insertion of a CdC
double bond of phenylallene into the Pd-C bond of [Pd-
(C6H3Me2-3,5)(bpy)(solvent)]BF4.6 [Pt(C6H4OMe)(L2)-
(MeCN)]BF4 (L2 ) 2,9-dimethylphenanthroline) was
reported to cause similar insertion of 1,1-dimethylallene
into the Pt-C bond, affording the corresponding (π-
allyl)platinum complex.3c The reaction of phenylallene
with the platinum complex 1-a ceton e also takes place
smoothly to produce the (π-allyl)platinum complex [Pt-
(η3-CH2CPhCHPh)(bpy)]BF4 (2), as shown in eq 4. The
is almost perpendicular to the π-allylic plane, while the
phenyl group bonded to the terminal carbon of the
ligand is coplanar with the π-allyl ligand.
1
The H NMR spectrum of 2-syn contains signals of
the three hydrogens of the allyl ligand at δ 3.69, 4.07,
and 4.55. The first two signals are coupled with each
other (J (HH) ) 3 Hz) and are assigned to the two d
CH2 hydrogens of the ligand. The signal at higher
magnetic field (δ 3.69) and the signal assigned to
benzylidene hydrogen (δ 4.55) show J (PtH) values of 67
and 70 Hz, respectively. The signal at δ 4.07 with a
smaller coupling constant (J (PtH) ) 23 Hz) is assigned
to the hydrogens at the syn position of the π-allylic
ligand. Heating the solution of 2-syn at 50 °C caused
its isomerization into 2-a n ti, which gave an equilibrated
mixture of the syn and anti isomers (52:48) in 8 days.
1
The H NMR spectrum of the mixture shows signals of
π-allyl hydrogens of 2-a n ti at δ 3.48 (J (PtH) ) 71 Hz),
4.42 (J (PtH) ) 23 Hz), and 6.39 (J (PtH) ) 42 Hz). The
first two signals are assigned to the two dCH2 hydro-
gens at anti and syn positions, respectively, on the basis
of the peak positions and J (PtH) values. The ben-
zylidene hydrogen signal at the syn position causes its
appearance at a lower magnetic field and a smaller
coupling constant as compared to those of 2-syn . The
isomerization between 2-syn and 2-a n ti occurs much
more slowly than for the Pd complex [Pd{η3-CH2C(C6H3-
Me2-3,5)CHPh}(bpy)]BF4, which is obtained as the
thermodynamically stable syn isomer soon after the
preparation.6
1H NMR spectrum of the reaction mixture shows the
existence of syn and anti isomers of 2. Recrystallization
of the product gives single crystals of 2-syn , whose
phenyl substituent occupies the syn position of the allyl
ligand. The molecular structure determined by X-ray
crystallography is shown in Figure 1. Despite the
unsymmetrical structure of the π-allyl ligand, the two
Pt-N bond distances and Pt-C1 and Pt-C3 bond
distances are similar within experimental error. The
phenyl plane bonded to the central carbon of the ligand
Contact of CO (1 atm) with 2-syn in MeCN causes
rapid conversion into a (σ-allyl)platinum complex, [Pt-
(CH2CPhdCHPh)(bpy)(CO)]BF4. The solution after the
reaction with CO for 4 min contains a mixture of the
isomer with a Z configuration, 3-Z, and the E isomer,
3-E, in a 72:28 ratio. The ratio between the isomers
decreases to 35:65 after 26 min and does not change
further. These results indicate that the complexes 3-Z
and 3-E are in equilibrium under the reaction condi-
(9) Huang, L.; Ozawa, F.; Osakada, K.; Yamamoto, A. J . Organomet.
Chem. 1990, 383, 587.
(10) (a) Dekker, G. P. C. M.; Elsevier, C. J .; Vrieze, K.; van Leeuwen,
P. W. N. M. Organometallics 1992, 11, 1598. (b) van Asselt, R.; Gielens,
E. E. C. G.; Ru¨lke, R. E.; Vrieze, K.; Elsevier, C. J . J . Am. Chem. Soc.
1994, 116, 977. (c) Groen, J . H.; Elsevier, C. J .; Vrieze, K.; Smeets, W.
J . J .; Spek, A. L. Organometallics 1996, 15, 3445. See also: Mecking,
S. Coord. Chem. Rev. 2000, 203, 325.
(11) For the related insertion of the CdC double bond of allene into
Pd-X and Pt-X bonds (X ) R, Cl, etc.), see: Powell, P. Synthesis of
η3-Allyl Complexes. In The Chemistry of the Metal-Carbon Bond;
Hartley, F. R., Patai, S. Eds.; Wiley: New York, 1982; pp 355-357.
Deeming, A. J .; J ohnson, B. F. G.; Lewis, J . J . Chem. Soc. D 1970,
598. Stevens, R. R.; Shier, G. D. J . Organomet. Chem. 1970, 21, 495.
Hughes, R. P.; Powell, J . J . Organomet. Chem. 1972, 34, C51. Hughes,
R. P.; Powell, J . J . Organomet. Chem. 1973, 60, 409. May, C. J .; Powell,
J . J . Organomet. Chem. 1980, 184, 385.
1
tions, as shown in eq 5. The H NMR spectrum of the
equilibrated mixture shows two singlets of CH2-Pt
hydrogens at δ 3.61 and 3.33 with large J (PtH) values
(94 and 112 Hz, respectively). Since the 1H NMR
spectrum of an initial reaction mixture of CO with 2-syn
shows the signal at δ 3.61 at a higher intensity than
that at δ 3.33, these peaks are assigned to 3-Z and 3-E,
respectively. Complexes 3-E and 3-Z exhibit vinylic
hydrogen signals at δ 6.79 and 6.88. The J (PtH) value
(22 Hz) of 3-E is larger than that of 3-Z (17 Hz), which

Phenylplatinum(II) Complexes with 2,2′-Bipyridine
Organometallics, Vol. 21, No. 10, 2002 2091
F igu r e 2. First-order plots of the isomerization of 3-Z to
3-E (a) under CO and (b) under argon. The reaction was
carried out in an NMR tube at 22 °C.
plexes 2-syn and 2-a n ti isomerize with a much slower
reaction rate. Scheme 1 depicts a plausible mechanism
of the isomerization to account for the above results.
Complex 3-Z, which is formed from the reaction of CO
with 2-syn , is equilibrated with an intermediate square-
pyramidal (π-allyl)platinum complex containing a car-
bonyl ligand (A), although trigonal-bipyramidal organ-
oplatinum complexes with a 2,9-dimethylphenanthroline
ligand were reported.3 The coexistence of π-allyl and
bipyridine ligands in A renders the square-planar
coordination more stable than the trigonal-bipyramidal
structure. The intermediate A undergoes the syn-anti
isomerization more rapidly than complex 2 with a
square-planar coordination. Partial loss of the carbonyl
ligand from A produces 2-syn , which is much slower
than the isomerization between 3-E and 3-Z both under
argon and under CO.
Oxid a tive Ad d ition of MeI to 1. Oxidative addition
of MeI to dimethyl- or diphenylplatinum(II) complexes
produces octahedral triorganoplatinum(IV) complexes
with a halogeno ligand.1,12-17 They are currently used
in the synthesis of organometallic polymers containing
Pt centers. The cationic monoorganoplatinum(II) com-
plexes seem to have a more electrophilic metal center
is consistent with the above assignment of the isomers.
These results suggest that the (σ-allyl)platinum complex
with an E configuration is thermodynamically more
stable than the Z isomer that is initially formed via
carbonylation of 2-syn . Figure 2a depicts a linear first-
order plot of the reaction, indicating that the isomer-
ization obeys the first-order kinetics of the complex. The
sum of the rate constants of the forward and reverse
reactions, (k1 + k-1 in eq 5) is 2.0 × 10-3 s-1 under CO
at 22 °C. The reaction under argon at the same tem-
perature occurs at a rate (k1 + k-1 ) 1.7 × 10-3 s-1
)
similar to that in CO. The small difference of the rate
constants between the reaction under argon and that
under CO is assigned to slow conversion of the (σ-allyl)-
platinum complex in part to form 2-syn irreversibly
during the reaction under argon.
The structural change between 3-E and 3-Z should
involve syn-anti isomerization of a (π-allyl)platinum
intermediate, although the square-planar π-allyl com-
Sch em e 1

2092 Organometallics, Vol. 21, No. 10, 2002
Yagyu et al.
In summary, the cationic phenylplatinum(II) complex
with 2,2′-bipyridine exhibits different reactivities in
insertion of small molecules into the Pt-C bond de-
pending on the coordinated solvent ligands. It undergoes
unprecedented oxidative addition of MeI to afford the
Pt(IV) complex with phenyl, methyl, and iodo ligands.
Allene inserts into the Pt(II)-phenyl bond to form (π-
allyl)platinum complexes whose structures are similar
to the palladium analogue reported previously. The (π-
allyl)platinum complex formed via insertion of allene
into the Pt(II)-phenyl bond reacts with CO to afford
the (σ-allyl)platinum complex, which undergoes cis-
trans isomerization via the (π-allyl)platinum intermedi-
ate with a carbonyl ligand.
F igu r e 3. ORTEP drawing of 4 (30% probability). Selected
bond lengths (Å) and angles (deg): Pt-I ) 2.581(3), Pt-
N1 ) 2.19(2), Pt-N2 ) 2.05(3), Pt-N3 ) 2.08(3), Pt-C1
) 2.25(2), Pt-C2 ) 2.01(3); I-Pt-N1 ) 97.5(7), I-Pt-N2
) 175.8(8), I-Pt-N3 ) 94.9(9), I-Pt-C1 ) 73.2(4), I-Pt-
C2 ) 92.4(9), N1-Pt-N2 ) 79(1), N1-Pt-C1 ) 167.9(7),
N2-Pt-C1 ) 111.3(9), N3-Pt-C2 ) 172(1).
Exp er im en ta l Section
Gen er a l Con sid er a tion , Mea su r em en t, a n d Ma ter ia ls.
Manipulations of the platinum complexes were carried out
under nitrogen or argon using standard Schlenk techniques.
Solvents were purified in the usual manner and stored under
argon. The other chemicals were commercially available. NMR
spectra were recorded on J EOL EX-400 and Varian MER-
CURY300 spectrometers. Elemental analyses were carried out
with a Yanaco MT-5 CHN autocorder.
and undergo oxidative addition of MeI less easily than
do the neutral diorganoplatinum complexes. The reac-
tion of MeI with 1-MeCN takes place slowly at room
temperature to produce Pt(IV) complexes after 9 days
(eq 6). One of the products, complex 4, was isolated as
P r ep a r a tion of [P tP h (NCMe)(bp y)]BF 4 (1-MeCN). To
a MeCN (2 mL) solution of PtPh2(bpy) (45.4 mg, 0.090 mmol)
was added an Et2O solution of HBF4 (54 wt % Et2O solution,
12 µL, 0.087 mmol) dropwise at 0 °C. The reaction mixture
was stirred continuously for 1 h. Et2O (25 mL) was added to
the mixture to induce separation of a colorless solid. The solid
product was collected by filtration and dried in vacuo to give
1-MeCN as an off-white solid (35.3 mg, 71%). 1-MeCN was
prepared also from the reaction of PtI(Ph)(bpy) with AgBF4
in MeCN (57%). Anal. Calcd for C18H16BF4N3Pt: C, 38.87; H,
2.90; N, 7.55. Found: C, 38.89; H, 3.12; N, 7.69. 1H NMR (300
MHz, CD3CN): δ 2.52 (s, CH3CN, J (PtH) ) 14 Hz), 7.08 (m,
1H, C6H5-p), 7.15 (m, 2H, C6H5-m), 7.35 (d, 2H, C6H5-o, J (HH)
) 7 Hz, J (PtH) ) 39 Hz), 7.48 (ddd, 1H, H5′-bpy, J (HH) ) 8,
6, 2 Hz), 7.82 (ddd, 1H, H5-bpy, J (HH) ) 7, 5, 2 Hz), 8.24 (ddd,
1H, H4′-bpy, J (HH) ) 8, 8, 2 Hz), 8.29* (1H, H6′-bpy), 8.32*
(H3′-bpy), 8.34 (ddd, 1H, H4-bpy, J (HH) ) 7, 7, 2 Hz), 8.39
(1H, H3-bpy), 8.89 (d, 1H, H6-bpy, J (HH) ) 5 Hz). The peaks
with asterisks are overlapped significantly with other signals.
P r ep a r a tion of [P tP h (a ceton e)(bp y)]BF 4 (1-a ceton e).
To PtI(Ph)(bpy) (190 mg, 0.34 mmol) dispersed in acetone (1
mL) was slowly added an acetone solution of AgBF4 (equimolar
to the Pt complex) to induce dissolution of the Pt complex, a
color change from yellow to orange, and separation of AgI.
After 5 min of the reaction, insoluble AgI was removed by
filtration. Reducing of the solvent under vacuum and subse-
quent addition of Et2O to the product caused separation of a
yellow solid that was dried in vacuo to give 1-a ceton e (141
mg, 72%). 1H NMR (400 MHz, acetone-d6): δ 2.08 (s, solvent),
7.04 (m, 1H, C6H5-p), 7.13 (m, 2H, C6H5-m), 7.30 (m, 2H, C6H5-
o, J (PtH) ) 33 Hz), 7.64 (ddd, 1H, H5′-bpy, J (HH) ) 8, 6, 2
Hz), 7.91 (ddd, 1H, H5-bpy, J (HH) ) 8, 5, 1 Hz), 8.40 (1H,
H4′-bpy), 8.42 (1H, H4-bpy), 8.53 (dd, 1H, H3-bpy, J (HH) )
5, 1 Hz), 8.57-8.60 (1H, H6′-bpy), 8.59-62 (1H, H3′-bpy), 8.66
(d, 1H, H6-bpy, J (HH) ) 8 Hz).
single crystals and characterized by X-ray crystal-
lography. The other isomer formed in the reaction
mixture was not isolated or characterized unambigu-
ously. Figure 3 depicts the molecular structure of 4 with
an octahedral coordination around the Pt center. The
phenyl and methyl ligands are situated at cis positions
in order to minimize the mutual trans effects. Complex
4 has methyl and iodo ligands at cis positions, which is
not consistent with the trans stereochemistry of the
oxidative addition of MeI to a late-transition-metal
center.1,12a This suggests the occurrence of isomerization
of the initial product with a labile MeCN ligand into 4.
(12) (a) J award, J . K.; Puddephatt, R. J . J . Organomet. Chem. 1976,
117, 297. (b) Scott, J . D.; Puddephatt, R. J . Organometallics 1986, 5,
2522. (c) Scott, J . D.; Puddephatt, R. J . Organometallics 1987, 5, 2522.
(d) Achar, S.; Scott, J . D.; Vittal, J . J .; Puddephatt, R. J . Organome-
tallics 1993, 12, 4592. (e) Rendina, L. M.; Vittal, J . V.; Puddephatt, R.
J . Organometallics 1995, 14, 2188. (f) Liu, G. X.; Puddephatt, R. J .
Organometallics 1996, 15, 5257.
(13) Uso´n, R.; Fornie´s, J .; Espinet, P.; Gar´ın, J . Synth. React. Inorg.
Met.-Org. Chem. 1977, 7, 211.
Attempts to purify 1-a ceton e by recrystallization from
acetone-Et2O were not successful, probably due to the ex-
change of the coordinated acetone with water contained in the
acetone during recrystallization and the lower solubility of
1-H2O as compared to 1-a ceton e. The obtained analytical
results suggest the formation of [PtPh(H2O)(bpy)]BF4 (1-H2O).
Anal. Calcd for C16H15BF4N2OPt: C, 36.04; H, 2.84; N, 5.25.
Found: C, 36.49; H, 3.33; N, 4.92. The reaction of PtI(Ph)-
(bpy) with AgBF4 in the presence of D2O produced [PtPh(D2O)-
(bpy)]BF4 (1-D2O), which exhibited the NMR signals at posi-
(14) (a) Byers, P. K.; Canty, A. J .; Crespo, M.; Puddephatt, R. J .;
Scott, J . D. Organometallics 1988, 7, 1363. (b) Aye, K.-T.; Canty, A.
J .; Crespo, M.; Puddephatt, R. J .; Scott, J . D.; Watson, A. A. Organo-
metallics 1989, 8, 1518. (c) Canty, A. J .; J in, H.; Penny, J . D. J .
Organomet. Chem. 1999, 573, 30. (d) Bayler, A.; Canty, A. J .; Edwards,
P. G.; Skelton, B. W.; White, A. H. J . Chem. Soc., Dalton Trans. 2000,
3325.
(15) De Felice, V.; Giovannitti, B.; De Renzi, A.; Tesauro, D.;
Panunzi, A. J . Organomet. Chem. 2000, 593-594, 445.
(16) Kuyper, J . Inorg. Chem. 1978, 17, 77.
(17) van Asselt, R.; Rijnberg, E.; Elsevier, C. J . Organometallics
1994, 13, 706.

Phenylplatinum(II) Complexes with 2,2′-Bipyridine
Organometallics, Vol. 21, No. 10, 2002 2093
tions different from those of 1-a ceton e. To PtI(Ph)(bpy) (34.6
mg, 0.0623 mmol) and AgBF4 (16.4 mg, 0.0845 mmol) dispersed
in acetone-d6 (0.7 mL) was added slowly to cause dissolution
of the Pt complex and separation of AgI. After 5 min of stirring
at room temperature, D2O (40 µL, 2.0 mmol) was added.
Insoluble AgI was removed by filtration before the 1H NMR
was measured. 1H NMR (300 MHz, acetone-d6): δ 6.97 (m,
1H, C6H5-p), 7.07 (m, 2H, C6H5-m), 7.39 (m, 2H, C6H5-o, J (PtH)
) 39 Hz), 7.57 (ddd, 1H, H5′-bpy, J (HH) ) 8, 6, 2 Hz), 8.00
(ddd, 1H, H5-bpy, J (HH) ) 8, 5, 1 Hz), 8.38 (ddd, 1H, H4′-
bpy, J (HH) ) 8, 8, 2 Hz), 8.43-8.45* (1H, H6′-bpy), 8.46 (ddd,
1H, H4-bpy, J (HH) ) 8, 8, 2 Hz), 8.57 (m, 1H, H3-bpy), 8.66
(m, 1H, H3′-bpy), 8.89 (m, 1H, H6-bpy). The peaks with
asterisks are overlapped significantly with other signals.
Rea ction of CO (1 a tm ) w ith 1-CH3CN a n d 1-a ceton e.
An acetone (1.5 mL) solution of AgBF4 (31.7 mg, 0.163 mmol)
was added to PtI(Ph)(bpy) (87.6 mg, 0.158 mmol) at room
temperature, which instantly caused separation of a white
solid of AgI. After separation of AgI, CO (1 atm) was introduced
to the solution containing 1-a ceton e, which caused separation
of a dark solid from the yellow solution. The formation of 1-CO
was completed within 3 h, on the basis of the results of 1H
NMR analyses of the reaction mixture. After the mixture was
stirred continuously for 10 h, the solid product was removed
by filtration, and the solvent was reduced under vacuum.
Addition of Et2O (40 mL) to the solution caused separation of
a white solid that was dried in vacuo to give 1-CO (52.6 mg,
61%). The reaction using CH3CN as a solvent gave the same
product in 5 days (55%). At this time, the reaction was not
completed. The reaction in an NMR tube caused complete
47.56; H, 3.35; N, 4.44. Found: C, 47.29; H, 3.26; N, 4.41.
Isolation of 2-syn was carried out by the same reaction without
stirring the solution. Allowing the solution of phenylallene with
1-a ceton e to stand for 48 h led to the growth of colorless
crystals that were collected by filtration and dried in vacuo to
give 2-syn (139 mg, 35%). 1H NMR (400 MHz, CD3CN): δ 3.69
(d, 1H, CH2, J (HH) ) 3 Hz, J (PtH) ) 67 Hz), 4.07 (d, 1H, CH2,
J (HH) ) 3 Hz, J (PtH) ) 23 Hz), 4.55 (s, 1H, CHPh, J (PtH) )
70 Hz), 7.15-7.35* (11H, 2C6H5, H5′-bpy), 7.44 (m, 1H, H6′-
bpy, J (PtH) ) 33 Hz), 7.80 (ddd, 1H, H5-bpy, J (HH) ) 2, 5, 7
Hz), 8.19 (ddd, 1H, H4′-bpy, J (HH) ) 2, 8, 8 Hz), 8.39* (1H,
H4-bpy), 8.40* (1H, H3′-bpy), 8.46 (m, 1H, H3-bpy), 9.30 (dd,
1H, H6-bpy, J (HH) ) 1, 5 Hz, J (PtH) ) 35 Hz). The peaks
with asterisks are overlapped significantly with other signals.
Th er m a l Isom er iza tion of 2-syn . In an NMR tube was
charged a CD3CN (0.5 mL) solution of 2-syn (12.4 mg, 0.0196
mmol) under Ar. The Pt complex was dissolved. The NMR tube
was heated in an oil bath (50 °C) and stored when not being
actively monitored. 1H NMR spectra were checked occasionally.
After reaction for 8 days, the 1H NMR spectrum showed signals
1
due to 2-syn and 2-a n ti in a 52:48 peak area ratio. H NMR
for 2-a n ti (400 MHz, CD3CN, obtained from the spectrum of
the above mixture of 2-syn and 2-a n ti): δ 3.48 (d, 1H, CH2,
J (HH) ) 3 Hz, J (PtH) ) 71 Hz), 4.42 (dd, 1H, CH2, J (PtH) )
23 Hz), 6.39 (s, 1H, CHPh, J (PtH) ) 42 Hz), 7.15-7.35* (10H,
2C6H5), 7.41-7.48* (1H), 7.28-7.70* (2H), 7.83 (ddd, 1H,
J (HH) ) 2, 5, 7 Hz), 8.31 (ddd, 1H, J (HH) ) 2, 8, 8 Hz), 8.35-
8.45* (1H), 9.20 (m, 1H, J (PtH) ) 34 Hz), 9.51 (m, 1H, J (PtH)
) 33 Hz). The peaks with asterisks are overlapped significantly
with other signals.
1
ligand substitution in 7 days. H NMR (400 MHz, CDCl3): δ
Rea ction of CO w ith 2-syn . A CD3CN (5 mL) solution of
2-syn (10.4 mg, 0.017 mmol) in a flask was degassed by a
pump-and-thaw cycle. CO (1 atm) was introduced into the
flask, and the solution was stirred for ca. 5 min. A part of the
deep yellow solution (0.5 mL) was transferred to an NMR tube
7.25-7.29* (1H, C6H5-p), 7.25-7.29* (2H, C6H5-m), 7.46 (m,
2H, C6H5-o, J (PtH) ) 32 Hz), 7.55 (ddd, 1H, H5′-bpy, J (HH)
) 7, 6, 1 Hz), 7.82-7.87* (1H, H5-bpy), 7.82-7.87* (1H, H6′-
bpy), 8.39 (m, 1H, H4-bpy), 8.46 (m, 1H, H4′-bpy), 8.83-8.87*
(1H, H3-bpy), 8.83-8.87*(1H, H3′-bpy), 8.83-8.87*(1H, H6-
bpy). The peaks with asterisks are overlapped significantly
with other signals. IR (KBr): ν(CtO) 2120 cm-1. Anal. Calcd
for C17H13BF4N2OPt: C, 37.59; H, 2.41; N, 5.16. Found: C,
37.16; H, 2.69; N, 5.20.
1
under CO. The H NMR spectrum indicates the formation of
3-Z and 3-E in a 72:28 molar ratio. The mixture of the original
solution and that in the NMR tube was kept for 24 h at room
temperature. Addition of Et2O (20 mL) to the solution caused
separation of a colorless solid that was isolated by decantation
1
of the solvent. The H NMR spectrum showed the existence of
Rea ction of CO (30 a tm ) w ith 1-CH3CN a n d 1-a ceton e.
An acetone (10 mL) solution of AgBF4 (53.5 mg, 0.275 mmol)
was added to PtI(Ph)(bpy) (149 mg, 0.269 mmol) at room
temperature, which instantly caused separation of AgI. After
separation of AgI, the solution was stirred under CO (30 atm)
for 13 h at room temperature. After the pressure was released,
a black solid was generated. The solid was removed by
filtration. The solvent was reduced under vacuum. Addition
of Et2O (40 mL) to the solution caused the separation of a white
solid that was dried in vacuo to give a mixture of [Pt(COPh)-
(bpy)(CO)]BF4 and 1-CO in an 82:18 molar ratio (59.0 mg).
1H NMR of [Pt(COPh)(bpy)(CO)]BF4 in the mixture of the
complexes (400 MHz, acetone-d6): δ 7.29 (m, 1H, C6H5-p), 7.60
(m, 2H, C6H5-m), 7.97 (m, 1H, H5′-bpy), 8.08 (m, 1H, H5-bpy),
8.48 (d, 2H, C6H5-o, J (HH) ) 7 Hz), 8.48 (d, 1H, H6′-bpy, J (HH)
) 7 Hz), 8.59-8.61* (1H, H4), 8.59-8.61* (1H, H4′), 8.85-8.92*
(1H, H3), 8.85-8.92* (1H, H3′), 9.19 (dd, 1H, H6-bpy, J (HH) )
5, 2 Hz). The peaks with asterisks are overlapped significantly
with other signals. IR (KBr): ν(CtO) 2066 cm-1, ν(CdO) 1647
1
a mixture of 3-Z and 3-E in a 34:66 molar ratio. H NMR of
3-Z (400 MHz, CD3CN): δ 3.61 (s, 2H, Pt-CH2, J (PtH) ) 94
Hz), 6.88 (s, 1H, CHPh, J (PtH) ) 17 Hz, overlapped partly
with aromatic hydrogen peaks). IR (KBr): ν(CtO) 2056 cm-1
.
1H NMR of 3-E (400 MHz, CD3CN): δ 3.33 (d, 2H, Pt-CH2,
J (HH) ) 1 Hz, J (PtH) ) 112 Hz), 6.79 (s, 1H, CHPh, J (PtH)
) 22 Hz). IR (KBr): ν(CtO) 2103 cm-1. Isomerization of 3-Z
into 3-E was monitored by the NMR measurement of the
solution under CO or argon.
Rea ction of MeI w ith 1-MeCN. To 1-MeCN (38.0 mg,
0.068 mmol) were added MeCN (1 mL) and MeI (3.4 g, 24
mmol), in that order. Stirring the yellow solution for 9 days
at room temperature caused separation of a yellow solid that
was collected by filtration, washed with Et2O, and dried in
1
vacuo (20.5 mg). The H NMR spectrum analyses of the solid
indicated two signals at δ 1.82 (J (PtH) ) 77 Hz) and 2.30
(J (PtH) ) 67 Hz) due to PtCH3 hydrogens and signals of
1
1-MeCN. H NMR of the major product (400 MHz, CD3CN):
cm-1
.
δ 1.82 (J (PtH) ) 77 Hz), 7.15-7.30 (5H, C6H5), 7.75 (ddd, 1H,
H5′-bpy, J (HH) ) 8, 6, 2 Hz), 7.95 (ddd, 1H, H5-bpy, J (HH) )
7, 5, 1 Hz), 8.20 (dd, 1H, H6′-bpy, J (HH) ) 6, 1 Hz, J (PtH) )
39 Hz), 8.30-8.35 (1H, H4′-bpy), 8.40 (ddd, 1H, H4-bpy, J (HH)
) 10, 8, 2 Hz), 8.54 (d, 1H, H3′-bpy, J (HH) ) 8 Hz), 8.61 (d,
1H, H3-bpy, J (HH) ) 8 Hz), 9.94 (m, 1H, H6-bpy, J (PtH) )
Rea ction of P h en yla llen e w ith 1-a ceton e. An acetone
(3 mL) solution of AgBF4 (133 mg, 0.68 mmol) was added to
PtI(Ph)(bpy) (350 mg, 0.63 mmol) at room temperature. The
resulting AgI was removed by filtration. To the solution
containing 1-a ceton e formed in situ was added phenylallene
(40 µL, 0.64 mmol). The reaction mixture was stirred for 48
h. Evaporation of the solvent to ca. 1 mL and addition of Et2O
to the solution caused separation of a colorless solid that was
collected by filtration and dried in vacuo. The NMR spectrum
indicated the presence of syn and anti isomers of [Pt(η3-CH2-
CPhCHPh)(bpy)]BF4 (2). Anal. Calcd for C25H21BF4N2Pt: C,
1
11 Hz). H NMR of the minor product (400 MHz, CD3CN): δ
8.92 (d, 1H, H6′-bpy, J (HH) ) 5 Hz), 10.00 (d, 1H, H6-bpy,
J (HH) ) 4 Hz, J (PtH) ) 38 Hz). Other signals were not
assigned due to low intensity and overlapping of the peaks.
Cr ysta l Str u ctu r e Deter m in a tion . Crystals of 2-syn and
4 suitable for X-ray diffraction study were obtained by slow

2094 Organometallics, Vol. 21, No. 10, 2002
Yagyu et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta of 2-syn a n d 4
ω-2θ scan method, and an empirical absorption correction (Ψ
scan) was applied. Scattering factors were taken from the
literature.18 Calculations were carried out using the program
package TEXSAN for Windows. Atomic scattering factors were
obtained from the literature. A full-matrix least-squares
refinement was used for non-hydrogen atoms with anisotropic
thermal parameters. Hydrogen atoms were located by assum-
ing the ideal geometry and included in the structure calcula-
tion without further refinement of the parameters. Crystal-
lographic data and details of refinement of the two complexes
are summarized in Table 1.
2-syn
4
chem formula
fw
C
25H21BF4N2Pt
C19H19BF4IN3Pt
698.18
631.35
cryst syst
space group
a, Å
b, Å
c, Å
monoclinic
P21/c (No. 14)
10.276(1)
20.401(5)
12.001(1)
110.697(9)
2353.3(6)
4
monoclinic
P21/n (No. 14)
12.606(3)
9.844(3)
17.836(4)
99.42(2)
2183.3(8)
4
â, deg
V, Å3
Z
µ, mm-1
F(000)
5.985
1216
1.782
7.859
1304
2.124
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research on Priority Areas,
“Molecular Physical Chemistry”, from the Ministry of
Education, Science, Culture, and Sports of J apan (No.
11166221). T.Y. is grateful for a fellowship from the
J SPS (J apan Society for the Promotion of Science).
D
calcd, g cm-3
cryst size, mm
2θ range, deg
no. of unique rflns
no. of used rflns
(I > 3.0σ(I))
no. of variables
R
0.75 × 0.15 × 0.15
5.0-55.0
5574
0.25 × 0.15 × 0.15
5.0-55.0
5304
2953
1880
298
0.067
0.068
257
0.079
0.057
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates, isotropic thermal parameters, and all bond lengths
and angles. This material is available free of charge via the
Internet at http://pubs.acs.org.
Rw
evaporation of an acetone solution and by recrystallization
from MeCN-Et2O, respectively, and mounted in glass capil-
lary tubes. Intensities were collected for Lorentz and polariza-
tion effects on a Rigaku AFC-5R automated four-cycle diffrac-
tometer by using Mo KR radiation (λ ) 0.710 69 Å) and the
OM0109105
(18) International Tables for X-ray Crystallography; Kynoch: Bir-
mingham, England, 1974; Vol. 4.