Reactions of a Platinum(III) Dimeric Complex with Alkynes in Water: Novel Approach to α-Aminoketone, α-Iminoketone, and α, β-Diimine via Ketonyl-Pt(III) Dinuclear Complexes

Article abstract of DOI:10.1021/ja0302634

Reaction of the platinum(III) dimeric complex [Pt₂(NH ₃)₄((CH₃)₃CCONH)₂(NO ₃)₂](NO₃)₂ (1), prepared in situ by the oxidation of the platinum blue complex [Pt₄(NH₃) ₈((CH₃)₃CCONH)₄](NO ₃)₅ (2) with Na₂S₂O₈, with terminal alkynes CH≡CR (R = (CH₂)_nCH ₃ (n = 2-5), (CH₂)_nCH₂OH (n = 0-2), CH₂OCH₃, and Ph), in water gave a series of ketonyl-Pt(III) dinuclear complexes [Pt₂(NH₃) ₄((CH₃)₃CCONH)₂(CH ₂COR)](NO₃)₃ (3, R = (CH₂) ₂CH₃; 4, R = (CH₂)₃CH₃; 5, R = (CH₂)₄CH₃; 6, R = (CH₂) ₅CH₃; 7, R = CH₂OH; 8, R = CH ₂CH₂OH; 9, R = (CH₂)₂CH ₂OH; 10, R = CH₂OCH₃; 11, R = Ph). Internal alkyne 2-butyne reacted with 1 to form the complex [Pt₂(NH ₃)₄((CH₃)₃CCONH) ₂(CH(CH₃)COCH₃)](NO₃)₃ (12). These reactions show that Pt(III) reacts with alkynes to give various ketonyl complexes. Coordination of the triple bond to the Pt(III) atom at the axial position, followed by nucleophilic attack of water and hydrogen shift from the enol to keto form, would be the mechanism. The structures of complexes 3·H₂O, 7·0.5C₃H₄O, 9, 10, and 12 have been confirmed by X-ray diffraction analysis. A competitive reaction between equimolar 1-pentyne and 1-pentene toward 1 produced complex 3 and [Pt₂(NH₃)₄((CH₃) ₃CCONH)₂(CH₂CH(OH)CH₂CH ₂CH₃)](NO₃)₃ (14) at a molar ratio of 9:1, suggesting that alkyne is more reactive than alkene. The ketonyl-Pt(III) dinuclear complexes are susceptible to nucleophiles, such as amines, and the reactions with secondary and tertiary amines give the corresponding α-amino-substituted ketones and the reduced Pt(II) complex quantitatively. In the reactions with primary amines, the once formed α -amino-substituted ketones were further converted to the iminoketones and diimines. The nucleophilic attack at the ketonyl group of the Pt(III) complexes provides a convenient means for the preparation of α-aminoketones, α-iminoketones, and diimines from the corresponding alkynes and amines.

Full text of DOI:10.1021/ja0302634

Published on Web 02/03/2004
Reactions of a Platinum(III) Dimeric Complex with Alkynes in
Water: Novel Approach to r-Aminoketone, r-Iminoketone,
and r,â-Diimine via Ketonyl-Pt(III) Dinuclear Complexes
Masahiko Ochiai, Yong-Shou Lin, Jun Yamada, Hanae Misawa, Saiko Arai, and
Kazuko Matsumoto*
Contribution from the Department of Chemistry, AdVanced Research Center for Science and
Engineering, Waseda UniVersity, Japan Science and Technology Corporation,
3-4-1 Ohkubo, Shinjuku, Tokyo 169-8555, Japan
Received April 29, 2003; E-mail: kmatsu@waseda.jp
Abstract: Reaction of the platinum(III) dimeric complex [Pt2(NH3)4((CH3)3CCONH)2(NO3)2](NO3)2 (1),
prepared in situ by the oxidation of the platinum blue complex [Pt4(NH3)8((CH3)3CCONH)4](NO3)5 (2) with
Na2S2O8, with terminal alkynes CHtCR (R ) (CH2)nCH3 (n ) 2-5), (CH2)nCH2OH (n ) 0-2), CH2OCH3,
and Ph), in water gave a series of ketonyl-Pt(III) dinuclear complexes [Pt2(NH3)4((CH3)3CCONH)2(CH2-
COR)](NO3)3 (3, R ) (CH2)2CH3; 4, R ) (CH2)3CH3; 5, R ) (CH2)4CH3; 6, R ) (CH2)5CH3; 7, R ) CH2OH;
8, R ) CH2CH2OH; 9, R ) (CH2)2CH2OH; 10, R ) CH2OCH3; 11, R ) Ph). Internal alkyne 2-butyne reacted
with 1 to form the complex [Pt2(NH3)4((CH3)3CCONH)2(CH(CH3)COCH3)](NO3)3 (12). These reactions show
that Pt(III) reacts with alkynes to give various ketonyl complexes. Coordination of the triple bond to the
Pt(III) atom at the axial position, followed by nucleophilic attack of water and hydrogen shift from the enol
to keto form, would be the mechanism. The structures of complexes 3‚H2O, 7‚0.5C3H4O, 9, 10, and 12
have been confirmed by X-ray diffraction analysis. A competitive reaction between equimolar 1-pentyne
and 1-pentene toward 1 produced complex 3 and [Pt2(NH3)4((CH3)3CCONH)2(CH2CH(OH)CH2CH2CH3)]-
(NO3)3 (14) at a molar ratio of 9:1, suggesting that alkyne is more reactive than alkene. The ketonyl-Pt(III)
dinuclear complexes are susceptible to nucleophiles, such as amines, and the reactions with secondary
and tertiary amines give the corresponding R-amino-substituted ketones and the reduced Pt(II) complex
quantitatively. In the reactions with primary amines, the once formed R-amino-substituted ketones were
further converted to the iminoketones and diimines. The nucleophilic attack at the ketonyl group of the
Pt(III) complexes provides a convenient means for the preparation of R-aminoketones, R-iminoketones,
and diimines from the corresponding alkynes and amines.
bridging ligands18 have been established as a new class of
high-valent platinum compounds, organoplatinum(III) chemistry
still remains to be explored. Just one mononuclear organo-
platinum(III) complex has been reported, but its reactivity is
not well-known.19 Dinuclear platinum(III) complexes having an
alkyl group at the axial position of the Pt(III)-Pt(III) bond are
relatively rare, and only two had been known before our
Introduction
Although Pt(III)-Pt(III) complexes having various bridging
ligands such as amidates,1-3 pyrimidines,1-9 other nitrogen
donor ligands,1,10 sulfur-containing ligands,1,4,5,11 acetates,1,4,5,12
pyrophosphites,13 phosphates,1,4,5,13,14 sulfates,1,5,14,15 and σ-carbon-
containing ligands,1,16,17 and the Pt(III)-Pt(III) complex without
(1) Lippert, B. Coord. Chem. ReV. 1999, 182, 263.
(2) Matsumoto, K. In Chemistry and Biochemistry of a Leading Anticancer
Drug; Lippert, B., Ed.; Wiley-VCH: New York, 1999; p 455.
(3) Matsumoto, K.; Sakai, K. AdV. Inorg. Chem. 1999, 49, 375
(4) Zangrando, E.; Pichierri, F.; Randaccio, L.; Lippert, B. Coord. Chem. ReV.
1996, 156, 275.
(5) O’Halloran, T. V.; Lippard, S. J. Isr. J. Chem. 1985, 25, 130.
(6) (a) Hollis, L. S.; Lippard, S. J. J. Am. Chem. Soc. 1981, 103, 6761. (b)
Hollis, L. S.; Lippard, S. J. Inorg. Chem. 1982, 21, 2116. (c) Hollis, L. S.;
Lippard, S. J. Inorg. Chem. 1983, 22, 2605. (d) Hollis, L. S.; Roberts, M.
M.; Lippard, S. J. Inorg. Chem. 1983, 22, 3637. (e) O’Halloran, T. V.;
Roberts, M. M.; Lippard, S. J. Inorg. Chem. 1986, 25, 957.
(7) Lippert, B.; Scho¨llhorn, H.; Thewalt, U. J. Am. Chem. Soc. 1986, 108,
525.
(12) (a) Appleton, T. G.; Byriel, K. A.; Garrett, J. M.; Hall, J. R.; Kennard, C.
H. L.; Mathieson, M. T.; Stranger, R. Inorg. Chem. 1995, 34, 5646 and
references therein. (b) Appleton, T. G.; Byriel, K. A.; Garrett, J. M.; Hall,
J. R.; Kennard, C. H. L.; Mathieson, M. T. J. Am. Chem. Soc. 1992, 114,
7305.
(13) (a) Roundhill, D. M.; Gray, H. B.; Che, C.-M. Acc. Chem. Res. 1989, 22,
55. (b) Zipp, A. P. Coord. Chem. ReV. 1988, 84, 47. (c) Cotton, F. A.;
Han, S.; Conder, H. L.; Walton, R. A. Inorg. Chim. Acta 1983, 72, 191.
(14) Stranger, R.; Nissen, S. C.; Mathieson, M. T.; Appleton, T. G. Inorg. Chem.
1997, 36, 937 and references therein.
(15) Cotton, F. A.; Falvello, L. R.; Han, S. Inorg. Chem. 1982, 21, 2889.
(16) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas, J. M.; Mart´ın, A.; Cotton, F. A.
J. Am. Chem. Soc. 1994, 116, 7160 and references therein.
(8) (a) Abe, T.; Moriyama, H.; Matsumoto, K. Chem. Lett. 1989, 1857. (b)
Abe. T.; Moriyama, H.; Matsumoto, K. Inorg. Chem. 1991, 30, 4198.
(9) Peilert, M.; Weibbach, S.; Freisinger, E.; Korsunsky, V. I.; Lippert, B. Inorg.
Chim. Acta 1997, 265, 187 and references therein.
(17) Yamaguchi, T.; Sasaki, Y.; Ito, T. J. Am. Chem. Soc. 1990, 112, 4038.
(18) (a) Baxter, L. A. M.; Heath, G. A.; Raptis, R. G.; Willis, A. C. J. Am.
Chem. Soc. 1992, 114, 6944. (b) Cini, R.; Fanizzi, F. P.; Intini, F. P.; Natile,
G. J. Am. Chem. Soc. 1991, 113, 7805.
(19) (a) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Menjo´n, B.; Bau, R.; Su¨nkel, K.;
Kuwabara, E. Organometallics 1986, 5, 1576. (b) Uso´n, R.; Fornie´s, J.;
Toma´s, M.; Menjo´n, B.; Su¨nkel, K.; Kuwabara, E.; Bau, R. J. Chem. Soc.,
Chem. Commun. 1984, 751.
(10) Cotton, F. A.; Matonic, J. H.; Murillo, C. A. Inorg. Chim. Acta 1997, 264,
61 and references therein.
(11) Umakoshi, K.; Kinoshita, I.; Ichimura, A.; Ooi, S. Inorg. Chem. 1987, 26,
3551 and references therein.
9
2536
J. AM. CHEM. SOC. 2004, 126, 2536-2545
10.1021/ja0302634 CCC: $27.50 © 2004 American Chemical Society

Reactions of a Pt(III) Dimeric Complex with Alkynes
A R T I C L E S
Scheme 1
to the olefins on the Pt(III)2 complex. In aqueous solution, the
double nucleophilic attack releases 1,2-dihydroxy addition
products. This is a new and very novel process of organoplati-
num(III) chemistry.25
Although ketonyl-transition-metal complexes had been
known,26 their reactivities such as alkylation reactions
have rarely been studied.27 To our knowledge, the nucleo-
philic attack of water, halides, and diethylamine on our
ketonyl-Pt(III)2 complex is the first example that a ketonyl
group on a transition metal undergoes nucleophilic attack.22,23
As an extension of our study on the chemistry of organo-
platinum(III) complexes, reactions with other unsaturated
organic substrates were examined. Here, we report the reaction
of complex 1 with alkynes in water to give ketonyl-Pt(III)
dinuclear complexes, which is the alternative route to prepare
the ketonyl-Pt(III) complex. In the previous report,22,23 the
reaction of the ketonyl-Pt(III) complex was examined with only
diethylamine, but in the present study the reaction was studied
also with tertiary and primary amines. The ketonyl complexes
undergo nucleophilic attack also by secondary and tertiary
amines to give amino-substituted ketones. In the reactions with
primary amines, the R-aminoketones are further converted to
iminoketones and diimines.
extensive study was started on the reactions of dinuclear
Pt(III) complexes with olefins: oxidative addition of methyl
iodide to the dinuclear pyrophosphite-bridged Pt(II) complex
K4[Pt2(P2O5H2)4], giving the Pt(III) complex K4[Pt2(P2O5H2)4-
MeI] with the methyl group at the axial position,20 and the
platinum(III) compound [Pt2(NH3)4(C5H5N2O2)3](SiF6)(NO3)‚
7H2O having 1-methyluracilate as both bridging and axial
ligands21 are the early rare examples of Pt(III)-C bonds at the
axial site.
Following the above two examples, the pivalamidate-bridged
platinum(III) dimeric complex [Pt2(NH3)4((CH3)3CCONH)2-
(NO3)2](NO3)2 (1) was found to react with acetone to give a
novel axial acetonyl-Pt(III)2 complex via C-H bond activation
of acetone (Scheme 1).22 Compound 1 is generated in situ by
the oxidation of the platinum blue complex [Pt4(NH3)8((CH3)3-
CCONH)4](NO3)5 (2) with HNO3. A general method for the
synthesis of ketonyl-platinum(III) complexes was developed
recently for various ketones.23
The chemistry of organoplatinum(III) dinuclear complexes
having pivalamidate bridging ligands has been further developed
by the finding that various olefins react with 1. Compound 1
reacts with linear terminal olefins in water to give â-hydroxy-
alkyl-Pt(III) complexes, and reaction of 1 with 4-penten-1-ol
gives the 2-methyltetrahydrofurfuryl complex as shown in
Scheme 1.24 Novel alkyl-Pt(III) complexes are also afforded
by the reactions with cyclic olefins in water or methanol
(Scheme 1).25 Axial coordination of the olefinic double bond
to one of the two platinum(III) atoms in 1, followed by
intra- or intermolecular nucleophilic attack, is proposed as the
reaction mechanism. Interestingly, the R-carbon atom on the
Pt(III) atom further undergoes the second nucleophilic attack,
and consecutive double nucleophilic attack has been realized
Results and Discussion
Reactions of Alkynes with Pt(III)2 Complex 1. Various
terminal CHtCR (R ) (CH2)nCH3 (n ) 2-5), (CH2)nCH2OH
(n ) 0-2), CH2OCH3, and Ph) and internal CH3CtCCH3
alkynes were used in the reactions. Addition of terminal alkynes
CHtCR to an aqueous solution of platinum(III) dimeric
complex 1, prepared in situ by the oxidation of platinum
blue complex 2 with Na2S2O8, at room temperature smoothly
gave the corresponding dinuclear ketonyl-Pt(III) com-
plexes [Pt2(NH3)4((CH3)3CCONH)2(CH2COR)](NO3)3 (3, R )
(CH2)2CH3; 4, R ) (CH2)3CH3; 5, R ) (CH2)4CH3; 6, R )
(CH2)5CH3; 7, R ) CH2OH; 8, R ) CH2CH2OH; 9, R )
(CH2)2CH2OH; 10, R ) CH2OCH3; 11, R ) Ph) as shown
in eq 1. Internal alkyne 2-butyne formed complex
[Pt2(NH3)4((CH3)3CCONH)2(CH(CH3)COCH3)](NO3)3 (12)
(eq 2), which had also been obtained previously from the
reaction of 2 with butanone in the presence of concentrated
HNO3, via C-H bond activation of the methylene group of
butanone.23 However, this reaction gave a mixture of the
1-butanonyl- and 3-butanonyl-Pt(III) dinuclear complexes
formed via C-H activation of the R-methyl and R-methylene
group, respectively. In contrast, the 3-butanonyl-Pt(III)2 com-
plex 12 is exclusively obtained in the present reaction of 1 with
2-butyne. In the latter reaction, the water attack at the two
possible alkynic carbon atoms π-coordinated to the Pt(III) atom
gives an identical compound.
(20) (a) Che, C.-M.; Schaefer, W. P.; Gray, H. B.; Dickson, M. K.; Stein, P.
B.; Roundhill, D. M. J. Am. Chem. Soc. 1982, 104, 4253. (b) Che, C.-M.;
Mak, T. C. W.; Gray, H. B. Inorg. Chem. 1984, 23, 4386.
(21) Scho¨llhorn, H.; Thewalt, U.; Lippert, B. J. Chem. Soc., Chem. Commun.
1986, 258.
(26) (a) Vicente, J.; Abad, A. J.; Chicote, M.-T.; Abrisqueta, M.-D.; Lorca, J.-
A.; Arellano, M. C. R. Organometallics 1998, 17, 1564 and references
therein. (b) Arndtsen, B. A.; Bergman, R. G. J. Organomet. Chem. 1995,
504, 143. (c) Veya, P.; Floriani, C.; Chiesi-Villa, A.; Rizzoli, C. Organo-
metallics 1993, 12, 4899. (d) Vicente, J.; Bermudez, M.-D.; Carrillo, M.-
P.; Jones, P. G. J. Organomet. Chem. 1993, 456, 305. (e) Fawcett, J.;
Henderson, W.; Jones, M. D.; Kemmitt, R. D. W.; Russell, F. R.; Lam, B.;
Kang, S. K.; Albright, T. A. Organometallics 1989, 8, 1991. (f) Bertani,
R.; Castellani, C. B.; Crociani, B. J. Organomet. Chem. 1984, 269, C15.
(g) Ito, Y.; Nakatsuka, M.; Kise, N.; Saegusa, T. Tetrahedron Lett. 1980,
21, 2873.
(22) Matsumoto, K.; Matsunami, J.; Mizuno, K.; Uemura, H. J. Am. Chem. Soc.
1996, 118, 8959.
(23) Lin, Y.-S.; Misawa, H.; Yamada, J.; Matsumoto, K. J. Am. Chem. Soc.
2001, 123, 569.
(24) Matsumoto, K.; Nagai, Y.; Matsunami, J.; Mizuno, K.; Abe, T.; Somazawa,
R.; Kinoshita, J.; Shimura, H. J. Am. Chem. Soc. 1998, 120, 2900.
(25) Lin, Y.-S.; Takeda, S.; Matsumoto, K. Organometallics 1999, 18, 4897.
(27) Seebach, D. Angew. Chem., Int. Ed. Engl. 1988, 27, 1624.
9
J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004 2537

A R T I C L E S
Ochiai et al.
Table 1. 1H NMR Data for Complexes 3-12a
1
3
4
5
6
7
8
complex (n, A, B)
H (2JPtH, Hz)
H (3JHH, Hz)
H (3JHH, Hz)
H (3JHH, Hz)
H (3JHH, Hz)
H (3JHH, Hz)
H (3JHH, Hz)
pivalamidate
1.18 (s)
3 (3, H, H)
5.01 (s, 79)
5.13 (s, 78)
5.01 (s, 78)
5.02 (s, 78)
4.98 (s, 79)c
5.03 (s, 79)
5.03 (s, 78)
4.90 (s, 73)
5.57 (s, 77)
5.52 (q, 78)
2.65 (t, 7.4)
2.67 (t, 7.3)
2.67 (t, 7.5)
2.67 (t, 7.4)
4.21 (s)
2.92 (t, 5.7)
2.75 (t, 6.9)
4.30 (s)
1.65 (m)
1.61 (m)
1.63 (m)
1.64 (m)
0.95 (t, 7.0)
1.34 (m)
1.33 (m)
1.32 (m)
4 (4, H, H)
0.90 (t, 7.0)
1.22 (m)
1.19 (s)
1.20 (s)
1.20 (s)
1.20 (s)
1.19 (s)
1.19 (s)
1.19 (s)
0.98 (s)
5 (5, H, H)
0.88 (t, 7.0)
1.2-1.1 (m)
6 (6, H, H)
1.2-1.1 (m)b
0.87 (t, 7)
7 (1, OH, H)
8 (2, OH, H)
9 (3, OH, H)
10d (1, OMe, H)
11e (0, Ph, H)
12f (1, H, CH3)
3.93 (t, 5.7)
1.87 (m)
3.63 (t, 6.7)
2.39 (s)
1.23 (s), and 1.15 (s)g
a The 1H NMR spectra were measured in D2O at room temperature by using Me4NClO4 as an internal reference at 3.19 ppm. b Overlapped by the signal
of the pivalamidate ligands. c The integration of the singlet is about 1.5H, probably due to the equilibrium and exchange with the enol form isomer in D2O
solution. d The methyl protons of the methoxy group appeared at 3.43 ppm. e Protons of the phenyl group: 8.16 (d, J ) 7.5 Hz, 2H), 7.75 (t, J ) 7.3 Hz,
3
1H), 7.60 (t, J ) 7.3 Hz, 2H). f The protons of the methyl group bound to the R-carbon atom appeared at 0.24 ppm (d, JHH ) 7.02). g The two peaks are
due to the two optical isomers caused by the chiral center at the R-carbon. The two isomers have been confirmed in the X-ray diffraction analysis.
3-12 are summarized in Table 1, in which the satellite signals
are observed for the C1 protons with the coupling constants of
73-79 Hz in all of the complexes. Formation of the ketonyl
complexes was also confirmed by the analysis of IR spectra,
which gave the characteristic CdO signals of the ketonyl groups
(see the Experimental Section). The structures of complexes 3,
7, 9, 10, and 12 were also confirmed by X-ray diffraction
analysis. All of the complexes obtained were the head to head
(H-H) isomer in the orientation of the two pivalamidate ligands,
and only a signal was observed for the pivalamidate methyl in
1
the H NMR spectra.
Although coordination of the triple bond to the platinum(III)
atom could not be observed, formation of the ketonyl-Pt(III)
dinuclear complexes suggests that the reaction starts with the
coordination of the alkyne triple bond to the N2O2-coordinated
Pt(III) atom in 1, which is followed by the nucleophilic attack
of water on the triple bond carbon atom and isomerization of
the enol to keto form via hydrogen transfer. In the reaction of
terminal alkynes, the water attack always takes place on the
internal carbon atom of the triple bond. This is the first example
of alkyne reaction on a platinum(III) complex, and is contarasted
with the well-known Pt(II)-alkyne complexes and their reactiv-
ity toward nucleophiles.28a,b Similar reactivities were reported
on other electrophilic metals such as Hg(II),28c Pd(II),28d and
Au(III).28e It is known that high-valent transition metals are less
susceptible to unsaturated organic substrates due to the poorer
back-donation from the metal center to the unsaturated bond.29
No platinum(IV)-alkyne complex has been reported except one
example: the platinum(IV) complex [PtMe2(CF3)(PMe2Ph)2]-
(PF6) reacts with 3-butyn-1-ol, HCtCCH2CH2OH, in acetone
to give an alkoxyalkyl- or -carbene-type complex.30 Formation
of the ketonyl complexes rather than alkoxyalkyl- or -carbene-
The reaction of 1 with excess 1-pentyne in D2O was
monitored with 1H NMR spectroscopy, which revealed that the
reaction is completed within 10 min at room temperature, and
(28) (a) Hartley, F. R. In ComprehensiVe Organometallic Chemistry; Wilkinson,
G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press: Oxford, 1982;
Vol. 6, p 471. (b) Chisholm, M. H.; Clark, H. C. Acc. Chem. Res. 1973, 6,
complex 1 is totally converted to the pentanonyl complex 3.
The expected axial π-coordination of 1-pentyne to the Pt(III)
atom before the water attack could not be observed, even though
the reaction was carried out at 0 °C. No intermediate was
observed in the spectra.
All of the complexes obtained were identified by the 1H NMR
spectra and elemental analysis. The 1H NMR data of complexes
202 and references therein. (c) Bassetti, M.; Floris, B.; Spadafora, G. J.
Org. Chem. 1989, 54, 5934. (d) For Pd-catalyzed nucleophile addition to
unsaturated carbon-carbon multiple bonds, see: Yamamoto, Y.; Radhakrish-
nan, U. Chem. Soc. ReV. 1999, 28, 199 and references therein. (e) Gasparrini,
F.; Giovannoli, M.; Misiti, D.; Natile, G.; Palmieri, G.; Maresca, L. J. Am.
Chem. Soc. 1993, 115, 4401.
(29) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principle and
Applications of Organotransition Metal Chemistry, 2nd ed.; Mill Valley,
CA, 1987.
(30) Chisholm, M. H.; Clark, H. C. J. Chem. Soc., Chem. Commun. 1971, 1484.
9
2538 J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004

Reactions of a Pt(III) Dimeric Complex with Alkynes
A R T I C L E S
Figure 2. ORTEP drawing of the cation of complex 7. Thermal ellipsoids
are drawn at the 30% probability level.
Figure 1. ORTEP drawing of the cation of complex 3. Thermal ellipsoids
are drawn at the 30% probability level.
type complexes in the reactions of complex 1 with 3-butyn-1-
ol and 4-pentyn-1-ol indicates that external nucleophilic attack
of water on the triple bond is the more preferable process in
our present reaction condition than the intramolecular hydroxy
attack as observed previously in the reaction of 1 with 4-penten-
1-ol.24 It is noteworthy that alkynes bearing electron-withdraw-
ing groups, such as HCtCCOOH and HCtCCOOEt, did not
form the corresponding ketonyl-Pt(III)2 complex.
Structure Analysis of Complexes 3‚H2O, 7‚0.5C3H4O, 9,
10, and 12. Yellow crystals of complexes 3‚H2O, 7‚0.5C3H4O,
9, 10, and 12 were obtained by addition of 1-pentyne, 2-propyn-
1-ol, 4-pentyn-1-ol, methyl propargyl ether, and 2-butyne,
respectively, to an aqueous solution of complex 1 prepared in
situ by oxidation of complex 2 with Na2S2O8 in aqueous HNO3
solution. The structures were identified by X-ray diffraction
analysis. The ORTEP drawings of the cations of complexes 3,
7, and 12 are given in Figures 1-3. The ORTEP drawings of
complexes 9 and 10 and other crystal data are in the Supporting
Information. In complexes 7 and 12, disorder of the axial ligand
is observed, and one (A part) of the two structures is shown in
Figures 2 and 3. Both of the disordered structures are also shown
in Figures S1 and S4 in the Supporting Information. The
refinements of these structures were carried out with the initial
occupancy of 0.5 for both components. The final occupancies
of the A parts of complexes 7 and 12 were 0.63 and 0.78,
respectively. The B parts could not be refined anisotropically,
and only isotropical thermal factors were given. No essential
difference was observed between the structures of 3 and its
hydroxy-substituted complex 9. The structures of 3, 7, 10, and
12 clearly indicate the formation of the ketonyl-Pt(III) com-
plexes with the axial Pt-C bonds. The bond lengths of Pt-C
are 2.105(18) in 3, 2.097(14) in 7, 2.088(10) in 10, and 2.146-
(13) Å in 12. These are slightly shorter (3, 7, and 10) and slightly
longer (12) than that in the acetonyl-Pt(III) dinuclear complex
[Pt2(NH3)4((CH3)3CCONH)2(CH2COCH3)](NO3)3 (13) (2.14
Å).22 The longer Pt-C bond in 12 may imply the steric
hindrance of the bulkier secondary carbon atom bound to the
Figure 3. ORTEP drawing of the cation of complex 12. Thermal ellipsoids
are drawn at the 30% probability level.
Pt(III) atom. The C2-O1 bond lengths range from 1.15(7) Å
in 7 (C2A-O1A) to 1.24(3) in 12 (C2A-O1A), and all these
distances together with the characteristic IR spectra are assigned
to CdO double bonds. The C1-C2 bond lengths of all
complexes are thought to be appropriate for C-C single bonds.
The torsion angles of Pt1-C1-C2-C3 and Pt1-C1-C2-O1
largely deviate from 0° or 180°, indicating that these atoms are
not in the same plane. From the above structural parameters, it
is suggested that these complexes have a character of the ketonyl
form at least in the solid state. However, the decreased intensity
of the proton resonance signal of the 1-position in 7 (Table 1)
suggests that there is equilibrium between the ketonyl and enol
forms of the complex in D2O solution. Equilibrium between
the π- and σ-type coordination was observed previously in the
Pt(III)2-CH2CHO complex in aqueous solution.24 The increased
contribution of the enol form in 7 compared to 3, 10, and 12 is
probably due to the hydroxyl group bound to the C3 of 7, which
stabilizes the enol form by hydrogen bonding. The distance
9
J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004 2539

A R T I C L E S
Ochiai et al.
halogens.29 By taking advantage of the electrophilic nature of
the ketonyl-Pt(III) dinuclear complexes, nucleophile-substituted
ketones were synthesized from the reactions of the ketonyl-
Pt(III) complexes; reactions with OH-, halides, and HNEt2
(secondary amines) released R-hydroxyketones, R-halogenoke-
tones, and diethylaminoketones, respectively.22,23 In the present
study, reactions with primary and tertiary amines as well as
secondary amines were examined.
Table 2. Selected Bond Distances for 3‚H2O, 7‚0.5C3H4O, 10,
and 12 (Å)
3‚H O
2
7‚0.5C H O
10
12
3 4
Pt1-Pt2
Pt1-C1
C1-C2
C1-C4
O1-C2
C2-C3
O2-C3
C3-C4
C4-C5
2.6879(9)
2.105(18)
1.41(3)
2.7002(7)
2.097(14)
1.50(2)
2.6928(5)
2.088(10)
1.503(17)
2.7221(16)
2.146(13)
1.44(3)
1.60(6)
1.23(3)
1.57(3)
1.15(7)
1.60 (2)
1.60(2)
1.221(18)
1.46(2)
1.40(2)
1.24(3)
1.45 (4)
Treatment of 3 with propylamine in CDCl3 at room temper-
ature generated the corresponding R-propylaminoketone, as
shown in eq 4. After 5 min, formation of the R-aminoketone
was confirmed with 1H NMR and GC/MS spectroscopy of the
reaction solution. After 24 h of the reaction, the R-aminoketone
totally disappeared and diimine appeared in the 1H NMR
spectrum as eq 4 shows. The latter product was also confirmed
1.43(3)
1.54(4)
Table 3. Selected Bond Angles and Torsion Angles (deg) for
3‚H2O, 7‚0.5C3H4O, 10, and 12
3‚H O
2
7‚0.5C H O
10
12
3 4
Bond Angles
1
with GC/MS spectroscopy. In the H NMR spectrum, 2-pen-
C1-Pt1-Pt2
C2-C1-Pt1
O1-C2-C1
C1-C2-C3
O1-C2-C3
173.5(6)
113.7(12)
126(2)
171.9(5)
112(2)
129(5)
100(3)
131(4)
169.4(4)
172.4(4)
111.5(11)
132(3)
112.9(18)
122.0(15)
118.9(13)
119.0(14)
tanone and unidentified products were also observed for the
reason mentioned below.
118.6(19)
115(2)
108(3)
119(3)
Torsion Angles
Pt1-C1-C2-O1
Pt1-C1-C2-C3
C4-C1-C2-C3
O1-C2-C3-O2
-94(2)
86.7(19)
-69(8)
110(6)
83.8(16)
-91.6(13)
66(4)
100.9(17)
33(4)
-3(12)
172.5(15)
between O1A and O2A is 2.69 Å, suggesting hydrogen bonding.
In the methoxy-substituted complex 10, such an effect is not
observed.
The selected bond lengths and bond angles of complexes 3‚
H2O, 7‚0.5C3H4O, 10, and 12 are listed in Tables 2 and 3.
Competitive Reaction of 1 with a Mixture of 1-Pentyne
and 1-Pentene. An equimolar mixture of 1-pentyne and
1-pentene was reacted with 1 in D2O at room temperature to
give complexes 3 and [Pt2(NH3)4((CH3)3CCONH)2(CH2CH-
(OD)CH2CH2CH3)](NO3)3 (14), respectively, at a molar ratio
of 9:1 on the basis of the 1H NMR analysis (eq 3). This indicates
that alkyne is more reactive than alkene. The result is in
accordance with the general tendency that alkynes more easily
coordinated to transition metals than alkenes.29
The reaction of 3 with a bulkier primary amine, tert-
butylamine, was also attempted. In this case R-aminoketone and
iminoketone were observed in the 1H NMR and GC/MS spectra
as in eq 5. It seems that bulkier tBuNH2 does not react with the
carbonyl groups of the iminoketone. A less reactive amine,
aniline, also reacts with 3, and only aminoketone is formed as
in eq 6. In this case, neither iminoketone nor diimine was
obtained.
Reactivity of the Ketonyl-Pt(III) Complexes toward
Amines. It is known that the alkyl groups in the previous alkyl-
platinum(III) complexes undergo nucleophilic attack.22,23,25 The
property is in contrast to the usual alkyl-transition-metal
complexes, which react with electrophiles, such as acid and
On the basis of the reactions of eqs 4-6, it is concluded that
primary amine reacts with 3 to give aminoketone, which is then
totally converted to iminoketone and finally to diimine, if the
amine is reactive enough and is not sterically bulky. To consider
9
2540 J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004

Reactions of a Pt(III) Dimeric Complex with Alkynes
A R T I C L E S
Scheme 2
The reaction of 3 with tertiary amine was also attempted,
and R-keto quaternary ammonium salt was formed as in eq 9.
the reaction mechanism, the model reaction was carried out as
follows. Bromoacetone having a leaving group in the R-position
of the carbonyl group was reacted with excess propylamine in
CDCl3. The reaction was monitored with 1H NMR spectroscopy,
and the same products as for the reaction of 13 with propylamine
were obtained (see the Experimental Section). Therefore, the
reaction mechanism is proposed as in Scheme 2. The once
formed R-aminoketone is still reactive and attacks the excess
bromoacetone or 13, and the resulting diacetonylpropylamine
undergoes intramolecular hydrogen transfer and elimination of
acetone to form the propyliminoacetone. The succeeding conver-
sion of the iminoketone to diimine is a well-known organic
reaction. The released acetone and unidentified products were
also observed in the 1H NMR spectrum. We could not identify
and quantify all of these products.
Complex 12 having a secondary carbon atom bound to the
Pt(III) atom gave no corresponding aminoketone in the reactions
with secondary and tertiary amines. In these cases, unidentified
decomposition products were observed in the 1H NMR spectra.
Only 3-buten-2-one was identified in a low yield in the reaction
with triethylamine (eq 10). This result indicates that the steric
hindrance and the electron-donating nature of the methyl group
bound to the R-carbon of the ketonyl ligand prevent the
nuclephilic attack of amines. However, primary amine PrNH2
can react with 12 to give 3-propylamino-2-butanone, 3-propy-
limino-2-butanone, and 5,6-dimethyl-4,7-diazadecane-4,6-diene
as a mixture (eq 11). All these compounds were identified by
comparison of the 1H NMR spectra with those of the authentic
samples.31
Treatment of the ketonyl complexes 3-6 with secondary
amine HNEt2 in CDCl3 at room temperature generated R-ami-
noketones Et2NCH2CO(CH2)nCH3 (n ) 2-5), respectively, in
quantitative amount as identified by 1H NMR and GC/MS
spectroscopy (eq 7). In the reactions, the corresponding plati-
num(II) dinuclear complex was released as a yellow precipitate.
The above reactions give a valuable route to prepare R-ami-
noketones from alkynes. The reactions proceed almost quanti-
tatively.
The reaction of 3 with less donating N-ethylaniline in CDCl3
gave only R-aminoketone as expressed in eq 8.
9
J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004 2541

A R T I C L E S
Ochiai et al.
Table 4. Reaction of the Ketonyl-Pt(III)2 Complexes with Amines
a Notes: (1) The yield was calculated on the basis of the 1H NMR integrations. Yield ) amt of product (mol)/amt of ketonyl-Pt(III) complex used (mol).
(2) Conversion ) amt of consumed ketonyl-Pt(III) (mol)/amt of ketonyl-Pt(III) complex used (mol).
The reaction of 3 with a less basic nucleophile, sodium
acetate, was also attempted in methanol, but no reaction
proceeded.
The reaction with secondary amines exclusively gives R-ami-
noketones. It is noteworthy that less donating amines such as
aniline and aniline derivatives or even a tertiary amine react
with the ketonyl-Pt(III) complex to give R-aminoketones. In
all of the reactions above, complex 1 was reduced to the Pt(II)2
dinuclear complex [Pt2(NH3)4((CH3)3CCONH)2]2+ and precipi-
tated as yellow powder. To confirm this, the 1H and 195Pt NMR
spectra were measured in D2O. In the 1H NMR spectrum, only
a singlet peak was observed at 1.0 ppm which is assigned to
the pivalamidate (tBu) protons of the Pt(II)2 dimer complex.
The chemical shift was exactly the same as for the reactions
previously reported for the Pt(II)2 dimer complex.22 The high-
field shift compared to the Pt(III) dimer (1.2 ppm) was caused
by the shielding effect of the lowered platinum oxidation state.
The above reactions are summarized in Table 4, and the
following conclusions can be drawn. Primary amines react with
complex 3 to form R-aminoketones. This reaction is noteworthy,
since primary amines usually react with carbonyl carbon atoms
of free ketones in the absence of the Pt(III) complex. The
R-aminoketones further undergo dehydrogenation to iminoke-
tones, and diimines are finally produced if the amines are not
too bulky. It is known that various ketones easily react with
the Pt(III) dinuclear complex 1 to form the corresponding
ketonyl-Pt(III) dinuclear complexes.23 Therefore, the Pt(III)
dinuclear complex is a good reaction center to convert either
ketones or alkynes to R-aminoketones, iminoketones, and
diimines.
(31) For preparing authentic compounds see: (a) Merck Index, 10th ed.; ONR-
92. (b) Kliegman, J. M.; Barnes, R. K. Tetrahedron 1970, 26, 2555,
9
2542 J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004

Reactions of a Pt(III) Dimeric Complex with Alkynes
A R T I C L E S
1
The 195Pt NMR spectrum also indicated the Pt(II) dinuclear
complex was formed. (see the Experimental Section).
ppm (D2O) for H and to Na2PtCl6 (external reference, 0 ppm) and
K2PtCl4 (external reference, -1624 ppm) for 195Pt. The mass spectra
were measured on a JEOL AUTOMASS spectrometer and JEOL SX-
102A spectrometer. The IR spectra were recorded on a HITACHI
I-3000 spectrometer. Alkynes, solvents, and amines were commercially
available ones. The platinum blue complex 224 was synthesized as
reported in the literature.
It is clear that the high electron-withdrawing ability of the
Pt(III) atom is responsible for the novel reactivity of the
ketonyl-Pt(III) complexes toward amines. In this regard, the
reactivity should be compared to those of Pt(IV) and Pt(II):
several nucleophilic attacks on alkyl-platinum(IV) complexes
and other high oxidation state metals such as Rh(III) were
reported previously.32 A detailed mechanistic study of the
reductive elimination step of the Pt(IV) complex fac-L2PtMe3-
(OR) (L ) bis(diphenylphosphino)ethane, o-bis(diphenylphos-
phino)benzene, R ) acetyl, aryl; L ) PMe3, R ) aryl) was
performed. In the reaction, C-O coupling or C-C coupling
products were given depending on the reaction conditions.32e
Nucleophilic attack of amines on the ketonyl-Pt(III)2 complexes
is caused by such a Pt(IV) character, whereas in Pt(II) chemistry,
nucleophilic attack is known only to a cationic alkyl-platinum-
(II) complex, and all other alkyl-Pt(II) complexes undergo
electrophilic attack. A methyl-Hg(II) complex is also known
to exhibit an electrophilic property.33 In these reported reaction
systems, however, reaction of ketonyl ligands is not reported.
The importance of the present reaction is that Pt(III) reacts with
alkynes and the resulting ketonyl-Pt(III) complexes undergo
nucleophilic attack.
Reaction of 1 with Alkynes. General Procedure. In a typical
experiment, to a solution of 2 (0.050 g, 0.0307 mmol) in water (1 mL)
was added Na2S2O8 (0.015 g, 0.0615 mmol) at room temperature. After
the dark blue solution completely changed to yellow, 1-pentyne (0.030
mL, 0.307 mmol) was added, and the mixture was stirred for 1 h at
room temperature. The reaction mixture was kept at 5 °C for 1 day to
give yellow precipitate, which was filtered, washed with cold water,
and dried to obtain a yellow powder of 3 (yield, 67%). Anal. Calcd for
C15H41N9O12Pt2: C, 19.38; H, 4.45; N, 13.56. Found: C, 19.38; H,
4.27; N, 13.12. IR: νCdO ) 1596 cm-1
.
The same procedure as for the reaction with 1-pentyne forming 3
was employed for the reactions with 1-hexyne, 1-heptyne, 1-octyne,
2-propyn-1-ol, 3-butyn-1-ol, 4-pentyn-1-ol, methyl propargyl ether,
phenylacetylene, and 2-butyne, giving complexes 4-12, respectively.
The 1H NMR spectra of complexes 11 and 12 were the same as those
of the reaction products of complex 2 with acetophenone and butanone,
respectively, in the presence of concentrated HNO3,23 showing the same
products are obtained. The yields and elemental analyses are as follows.
(4) Yield: 65%. Anal. Calcd for C16H43N9O12Pt2: C, 20.36; H, 4.59;
N, 13.36. Found: C, 19.97; H, 4.62; N, 13.11. IR: νCdO ) 1599 cm-1
(5) Yield: 70%. Anal. Calcd for C17H45N9O12Pt2: C, 21.32; H, 4.74;
N, 13.16. Found: C, 20.96; H, 4.58; N, 12.89. IR: νCdO ) 1599 cm-1
(6) Yield: 45%. Anal. Calcd for C18H47N9O12Pt2: C, 22.25; H, 4.87;
N, 12.97. Found: C, 22.44; H, 4.65; N, 12.99. IR: νCdO ) 1598 cm-1
(7‚0.5C3H4O) Yield: 55%. Anal. Calcd for C14.5H39N9O13.5Pt2: C, 18.42;
H, 4.16; N, 13.33. Found: C, 18.46; H, 4.02; N, 13.08. IR: νCdO
1585 cm-1. (8) Yield: 67%. Anal. Calcd for C14H39N9O13Pt2: C, 18.05;
H, 4.22; N, 13.53. Found: C, 18.37; H, 3.88; N, 13.24. IR: νCdO
1594 cm-1. (9) Yield: 88%. Anal. Calcd for C15H41N9O13Pt2: C, 19.05;
H, 4.37; N, 13.33. Found: C, 18.97; H, 4.37; N, 12.98. IR: νCdO
1632 cm-1. (10) Yield: 55%. Anal. Calcd for C14H39N9O13Pt2: C, 18.05;
H, 4.22; N, 13.53. Found: C, 17.82; H, 4.05; N, 13.16. IR: νCdO
1597 cm-1. (11) Yield: 70%. Anal. Calcd for C18H39N9O12Pt2: C, 22.43;
H, 4.08; N, 13.08. Found: C, 22.14; H, 3.95; N, 12.53. IR: νCdO
1597 cm-1. (12) Yield: 69%. Anal. Calcd for C14H39N9O12Pt2: C, 18.36;
H, 4.29; N, 13.77. Found: C, 18.16; H, 4.20; N, 13.46. IR: νCdO
1600 cm-1
.
Conclusions
Treatment of the Pt(III)2 dimer complex 1 with a series of
alkynes in aqueous solution leads to formation of the corre-
sponding ketonyl-platinum(III) dinuclear complexes. The
process involves initial axial π-coordination of the triple bond
to the Pt(III) atom, followed by nucleophilic attack of water.
Such alkyne to ketonyl transformation shows the strong electron-
withdrawing effect of Pt(III). Interestingly, the ketonyl-
platinum(III) compounds react with amines to give various
R-amino-substituted ketones. Primary, secondary, and tertiary
amines react with the ketonyl-platinum(III) complexes. In the
reaction with primary amines, the resulting R-aminoketones
further undergo conversion to R-iminoketones and diimines.
Although quite a number of ketonyl-transition-metal com-
pounds are known, ketonyl ligands usually do not show
reactions, and their reactivity is limited. The present reactions
are almost the first to release conversion products.
.
.
)
)
)
)
)
)
.
Method for the Preparation of the Crystals of 3‚H2O,
7‚0.5C3H4O, 9, 10, and 12. To complex 2 (0.010 g, 0.00615 mmol) in
H2O (0.5 mL) was added Na2S2O8 (0.003 g, 0.012 mmol). The mixture
was stirred for 10 min at room temperature to give a yellow solution.
Addition of concentrated HNO3 (0.050 mL) and 1-pentyne (0.020 mL)
to the yellow solution and letting the mixture stand for a few days at
room temperature gave yellow crystals of 3‚H2O. Using 2-propyn-1-
ol, 4-pentyn-1-ol, methyl propargyl ether, and 2-butyne instead of
1-pentyne afforded yellow crystals of 7‚0.5C3H4O, 9, 10, and 12, which
were used for the X-ray diffraction analysis.
It should be emphasized here that, without the Pt(III)2
complex, ketones react with amines at the carbonyl carbon to
give Schiff bases. Considering the easy ketonyl-Pt(III)2 com-
plex formation from ketones,23 the present reaction provides a
unique method for R-nucleophile modification of ketones.
Experimental Section
Carbon, hydrogen, and nitrogen analyses were carried out on a
Perkin-Elmer PE 2400II elemental analyzer. The 1H NMR spectra were
recorded on a JEOL EX-270 spectrometer operating at 270 MHz for
1H and on a JEOL Lambda 500 spectrometer operating at 107.3 MHz
for 195Pt. Chemical shifts are reported in δ units (parts per million,
ppm) referenced to Me4Si at 0 ppm (CDCl3) or to Me4NClO4 at 3.19
Competitive Reaction of 1-Pentyne and 1-Pentene with Complex
1. To a solution of complex 1 (0.016 g, 0.01 mmol) in D2O (0.6 mL)
was added Na2S2O8 (0.005 g, 0.02 mmol). After the dark blue solution
was converted to yellow, the solution was transferred to an NMR tube,
and 1-pentyne (0.01 mL, 0.1 mmol) and 1-pentene (0.011 mL, 0.1
mmol) were added. After 1 h at room temperature, the reaction mixture
was analyzed with 1H NMR spectroscopy, which indicates the formation
(32) (a) Luinstra, G. A.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 1993,
115, 3004. (b) Sen, A.; Lin, M.; Kao, L.-C.; Hutson, A. C. J. Am. Chem.
Soc. 1992, 114, 6385. (c) Romero, P.; Valderrama, M.; Contreras, R.; Boys,
D. J. Organomet. Chem. 2003, 673, 102. (d) Weinberg, E. L.; Baird, M.
C. J. Organomet. Chem. 1979, 179 (4), C61. (e) Williams, B. S.; Goldberg,
K. I. J. Am. Chem. Soc. 2001, 123, 2576.
1
of complexes 3 and 14 at a molar ratio of 9:1. H NMR (D2O, δ, 270
MHz, 293 K) for 14: 4.51 (dd, 1H, 2JPtH ) 38 Hz, 2JHH ) 7.6 Hz, 3JHH
) 3.0 Hz, PtCH2), 4.01 (t, 1H, 2JHH ) 7.6 Hz, 3JHH ) 7.6 Hz PtCH2),
3.72 (m, 1H, CH2CH(OH)CH2), 1.79 (q, 2H, 3JHH ) 7.6 Hz, CH2CH2-
(33) Periana, R. A.; Taube, D. J.; Evitt, E. R.; Loffler, D. G.; Jwentrcek, P. R.;
Voss, G.; Masuda, T. Science 1993, 259, 340.
9
J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004 2543

A R T I C L E S
Ochiai et al.
Table 5. Summary of the Crystal Data for Complexes 3‚H2O, 7‚0.5C3H4O, 10, and 12
3‚H O
2
7‚0.5C H O
10
12
3 4
empirical formula
fw
C15H43N9O13Pt2
947.76
C14.5H39N9O13.5Pt2
949.76
C14H39N9O13Pt2
931.72
C14H39N9O12Pt2
915.72
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
triclinic
triclinic
monoclinic
P21/c
9.4625(4)
10.0973(4)
30.1278(12)
90
96.449(1)
90
2860.4(2)
293 ( 2
4
triclinic
P1h (No.2)
9.6251(17)
10.1925(18)
15.986(3)
84.335(3)
78.348(4)
89.358(3)
1528.4(5)
223 ( 1
P1h (No.2)
9.6133(6)
10.0893(7)
17.1561(11)
106.867(1)
100.741(1)
93.340(1)
1533.3(2)
298 ( 1
P1h (No.2)
9.807(8)
10.045(8)
14.742(11)
88.363(14)
82.960(14)
84.854(14)
1433.5(19)
293 ( 2
T (K)
Z
F
2
2
2
calcd (gcm-3
)
2.024
1.932
2.164
2.122
cryst dimens (mm)
0.5 × 0.3 × 0.1
0.3 × 0.2 × 0.1
0.4 × 0.3 × 0.09
0.5 × 0.3 × 0.1
abs coeff (cm-1
)
92.11
90.57
98.14
98.16
2θ range (deg)
4 < 2θ < 55
3198 (I > 2σ(I))
360
0.075
0.190
2.5 < 2θ < 46
4412 (I > 2σ(I))
357
0.046
0.124
2.7 < 2θ < 62
8349 (I > 2σ(I))
328
0.056
0.143
2.8 < 2θ < 47
4060 (I > 2σ(I))
347
0.036
0.093
no. of obsd unique reflns
no. of params
R a
b
Rw
GOFc
0.990
0.942
1.097
1.057
2
2
a R ) ∑||Fo| - |Fc ||/∑|Fo|. b Rw ) [∑w(|Fo | - |Fc |)2/∑wFo ]1/2, w ) 1/σ2(Fo). c GOF ) [∑w(Fo - Fc 2)2/∑(n - p)].1/2
CH2), 1.49 (quin, 2H, 3JHH ) 7.6 Hz, CH2CH2CH3), 1.19 (s, 18H, 2Me3-
CCONH), 0.96 (t, 3H, JHH ) 7.0 Hz, CH2CH3).
7.4 Hz, 3H, NC2H4CH3), 0.91 (t, J ) 7.3 Hz, 3H, H5). MS (EI) m/z
(relative intensity): 182 (M+, 2), 153 (M+ - Et, 91), 111 (21), 96 (9),
84 (52), 70 (100). A similar reaction was attempted with the acetonyl-
Pt(III) dinuclear complex 13 (0.015 g) and 5 equiv of PrNH2. The
3
Reactions of Ketonyl-Platinum(III) Dinuclear Complexes with
Amines. The reactions of the 1-pentanonyl complex 3 with primary,
secondary, and tertiary amines were examined as follows. In a typical
experiment, to a suspension of 1-pentanonyl-diplatinum(III) complex
3 (0.018 g, 0.02 mmol) in CDCl3 (0.6 mL) was added PrNH2 (0.10
mmol) at room temperature. After the mixture was stirred for 5 min,
the yellow precipitate of the reduced diplatinum(II) complex [Pt(II)2-
(NH3)4((CH3)3CCONH)2]2+ was filtered off, and the pale yellow filtrate
1
reaction was followed with H NMR and GC/MS spectroscopy, and
the formation of PrNHCH2COCH3 and PrNdCC(dNPr)CH3 was
confirmed. The assignment of the peaks for the latter diimine compound
was done by comparison with the authentic compound prepared from
pilvinaldehyde (OHCCOCH3) and PrNH2. The GC/MS spectrum of
PrNdCC(dNPr)CH3 shows that the largest peak is not the mother peak,
but the M+ - Et peak, and it seems that the mother ion easily loses
the Et group in GC/MS. 1H NMR (CDCl3, δ, 270 MHz) for
1
was analyzed with H NMR and GC/MS spectroscopy. Both of the
spectra identified PrNHCH2CO(CH2)2CH3 in the solution as the
exclusive product. The yellow precipitate was confirmed to be the
Pt(II) dinuclear complex [Pt(II)2(NH3)4((CH3)3CCONH)2]2+ with 195Pt
3
1-propylamino-2-propanone: 3.53 (s, 2H, NHCH2CO), 2.54 (t, JHH
) 7.2 Hz, 2H, NHCH2C2H5), 2.14 (s, 3H, COCH3), 1.50 (q, 2H,
NHCH2CH2CH3), 0.92 (t, 3H, NHC2H4CH3). MS (EI) for 1-propyl-
amino-2-propanone, m/z (relative intensity): 115 (M+, 14), 100 (4),
86 (46), 73 (100), 57 (62). Yield for 5-methyl-4,7-diazadecane-4,6-
diene: 46% (conversion of 13, 92%). 1H NMR (CDCl3, δ, 270 MHz)
for 5-methyl-4,7-diazadecane-4,6-diene: 7.81 (s, 1H, NdCHCdN),
1
NMR spectroscopy in D2O. H NMR (CDCl3, δ, 270 MHz): 3.49 (s,
2H, H1), 2.53 (t, 3JHH ) 7.1 Hz, 2H, NHCH2C2H5), 2.37 (t, 3JHH ) 7.3
Hz, 2H, H3), 1.63 (m, 2H, H4), 1.52 (m, 2H, NHCH2CH2CH3), 0.93 (t,
3JHH ) 7.3 Hz, 3H, NHC2H4CH3), 0.92 (t, 3JHH ) 7.4 Hz, 3H, H5). MS
(EI) m/z (relative intensity): 112 (M+ - Et - 2H, 16), 99 (4), 84 (33),
70 (100). 195Pt{1H} NMR of the Pt(II) dinuclear complex (D2O, δ, 107.3
MHz): -1425 (H-H, N2O2-coordinated), -2376 (H-H, N4-coordi-
nated), and -1923 (H-T, N3O-coordinated). The assignment of these
peaks was done by comparison with the reported data of the Pt(II)
dinuclear complexes having analogous bridging ligands3 and with that
of the in situ generated pivalamidate-bridged Pt(II) dinuclear complex.34
The fast HH-HT isomerization was also reported in the acetamidate-
bridged platinum(II) dinuclear complex.35
3
3
3.52 (t, JHH ) 7.0 Hz, 2H, NCH2C2H5), 3.43 (t, JHH ) 7.0 Hz, 2H,
NCH2C2H5), 2.17 (s, 3H, COCH3), 1.71 (m, 4H, NCH2CH2CH3), 1.05
(m, 6H, NC2H4CH3). MS (EI) for 5-methyl-4,7-diazadecane-4,6-diene,
m/z (relative intensity): 154 (M+, 3), 125 (M+ - Et, 100), 96 (63), 83
(41), 69 (23), 56 (21).
For comparison, a bulkier primary amine, tert-butylamine, was used
for the reaction with 3. To a suspension of 3 (0.015 g) in CDCl3 (0.6
mL) was added tert-butylamine (5 equiv), and the solution was reacted
for 6 h at room temperature. The solution gave a yellow precipitate of
the pivalamidate-bridged Pt(II) dinuclear complex, which was filtered
off, and the solution was analyzed with 1H NMR spectroscopy. Different
from propylamine, bulky tert-butylamine did not react immediately;
The above solution was further reacted for 24 h, and by using CHCl2-
CHCl2 as the internal reference, the 1H NMR and GC/MS spectra were
measured in CDCl3 after the excess PrNH2 was expelled with N2 stream.
Both of the spectra showed that the original peaks of PrNHCH2CO-
(CH2)2CH3 totally disappeared and new peaks ascribed to PrNdCC-
(dNPr)Pr appeared. Yield: 45% (conversion of 3, 90%). 1H NMR
t
however, after 3 days of the reaction, aminoketone BuNHCH2CO-
t
(CH2)2CH3 and iminoketone BuNdCHCO(CH2)2CH3 were gradually
1
3
(CDCl3, δ, 270 MHz): 7.74 (s, 1H, H1), 3.51 (t, JHH ) 7.5 Hz, 2H,
produced. Yield for 1-tert-butylamino-2-pentanone: 15%. H NMR
(CDCl3, δ, 270 MHz) for 1-tert-butylamino-2-pentanone: 4.24 (s, 2H,
H1), 2.41 (t, J ) 7.3 Hz, 2H, H3), 1.61 (m, 2H, H4), 0.92 (t, J ) 7.3
Hz, 3H, H5). MS (EI) for 1-tert-butylamino-2-pentanone, m/z (relative
intensity): 157 (M+, 4), 127 (79), 113 (34), 86 (80). Yield for 1-tert-
butylimino-2-pentanone: 30% (conversion of 3, 60%). 1H NMR
(CDCl3, δ, 270 MHz) for 1-tert-butylimino-2-pentanone: 7.56 (s, 1H,
H1), 2.82 (t, J ) 7.3 Hz, 2H, H3), 1.64 (m, 2H, H4), 0.95 (t, J ) 7.3
Hz, 3H, H5). MS (EI) for 1-tert-butylimino-2-pentanone, m/z (relative
NCH2C2H5), 3.48 (t, J ) 7.1 Hz, 2H, NCH2C2H5), 2.56 (t, J ) 7.6 Hz
2H, H3), 1.73 (m, 2H, NCH2CH2CH3), 1.68 (m, 2H, NCH2CH2CH3),
1.61 (m, 2H, H4), 0.98 (t, J ) 7.4 Hz, 3H, NC2H4CH3), 0.96 (t, J )
(34) Kodzasa, T.; Kamata, T.; Matsuda, H.; Fukaya, T.; Mizukami, F.;
Matsunami, J.; Nagai Y.; Matsumoto, K. J. Sol-Gel Sci. Technol. 1997, 8,
1029.
(35) Erxleben, A.; Mutikainen, I.; Lippert, B. J. Chem. Soc., Dalton Trans. 1994,
3667.
9
2544 J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004

Reactions of a Pt(III) Dimeric Complex with Alkynes
A R T I C L E S
intensity): 155 (M+, 10), 140 (100), 127 (79), 113 (34), 84 (72).
Reaction of more than 3 days resulted in the decomposition of the
complex. A slightly better yield of 1-tert-butylimino-2-pentanone was
realized by performing the reaction at 40 °C for 2 days (Table 4,
entry 4).
The reaction with complex 5 gave 1-diethylamino-2-heptanone,
which was confirmed with 1H NMR and GC/MS spectra. Yield: 100%.
1H NMR (CDCl3, δ, 270 MHz): 3.14 (s, 2H, H1), 2.49 (q, J ) 7.2 Hz,
4H, N(CH2CH3)2), 2.39 (t, J ) 7.5 Hz, 2H, H3), 1.51 (m, 2H, H4),
1.3-1.1 (m, 4H, H5 and H6), 0.99 (t, J ) 7.2 Hz, 6H, N(CH2CH3)2),
0.82 (t, J ) 7.0 Hz, 3H, H7). MS (EI) m/z (relative intensity): 185
(M+, 3), 170 (5), 112 (4), 87 (100), 58 (96).
The reaction of 3 with aniline was carried out for 6 h, similar to
other amines described above, and the 1H NMR spectrum of the filtrate
showed that only aminoketone was formed. Yield: 84%. 1H NMR
(CDCl3, δ, 270 MHz): 3.97 (s, 2H, H1), 2.48 (t, J ) 7.2 Hz, 2H, H3),
1.69 (m, 2H, H4), 0.95 (t, J ) 7.3 Hz, 3H, H5). MS (EI) m/z (relative
intensity): 177 (M+, 4), 106 (M+ - COC3H7, 100), 77 (15).
The reaction of complex 12 having a secondary carbon atom bound
to the Pt(III) atom with propylamine was carried out as follows. To a
suspension of 12 (0.009 g) in CDCl3 (1.0 mL) was added propylamine
(5 equiv), and the solution was monitored with 1H NMR spectroscopy
for 7 days at room temperature. After the mixture was stirred for 6 h,
3-propylamino-2-butanone appeared. At the same time, 3-propylimino-
2-butanone and 5,6-dimethyl-4,7-diaza-4,6-decadiene were gradually
formed. After 28 h, these compounds were observed as a mixture in
low yields. The three products were identified by comparison with the
1H NMR spectra of the authentic compounds. Yield of 3-propylamino-
The reaction with complex 6 gave 1-diethylamino-2-octanone, which
1
1
was confirmed with H NMR and GC/MS spectra. Yield: 100%. H
NMR (CDCl3, δ, 270 MHz): 3.13 (s, 2H, H1), 2.47 (q, J ) 7.2 Hz,
4H, N(CH2CH3)2), 2.39 (t, J ) 7.1 Hz, 2H, H3), 1.49 (m, 2H, H4),
1.3-1.0 (m, 6H, H5 and H6, and H7), 0.96 (t, J ) 7.2 Hz, 6H,
N(CH2CH3)2), 0.81 (t, J ) 6.9 Hz, 3H, H8). MS (EI) m/z (relative
intensity): 199 (M+, 47), 198 (53), 184 (85), 170 (10), 156 (19), 142
(14), 128 (13), 114 (71), 102 (68), 91 (100), 73 (80), 59 (98).
The reaction of 3 with N-ethylaniline was performed at 40 °C for
24 h as described above to give the corresponding aminoketone Ph-
(Et)NCH2CO(CH2)2CH3 Yield: 86%. 1H NMR (CDCl3, δ, 270 MHz):
3.95 (s, 2H, H1), 3.46 (q, J ) 7.2 Hz, 2H, NCH2CH3), 2.43 (t, J ) 7.3
Hz, 2H, H3), 1.61 (q, J ) 7.4 Hz, 2H, H4), 1.20 (t, J ) 7.2 Hz, 3H,
NCH2CH3), 0.90 (t, J ) 7.4 Hz, 3H, H5). MS (EI) m/z (relative
intensity): 205 (M+, 7), 198 (M+ - COC3H7, 100), 106 (21), 77 (12).
The reaction of 3 with triethylamine was carried out for 6 h to give
the corresponding R-keto quaternary ammonium ion Et3N+CH2CO-
(CH2)2CH3. Yield: 80%. 1H NMR (CDCl3, δ, 270 MHz): 4.83 (s, 2H,
H1), 3.62 (q, J ) 7.6 Hz, 6H, N(CH2CH3)3), 2.63 (t, J ) 7.5 Hz, 2H,
H3), 1.63 (q, J ) 7.5 Hz, 2H, H4), 1.35 (t, J ) 7.6 Hz, 9H, N(CH2CH3)3),
0.93 (t, J ) 7.3 Hz, 3H, H5). MS (FAB) m/z (relative intensity): 186
(M+).
1
2-butanone: 8%. H NMR (CDCl3, δ, 270 MHz) of 3-propylamino-
2-butanone:31a 3.30 (q, 1H, 7.2 Hz, CH3CH(NHPr)CO), 2.42 (t, 2H,
7.0 Hz, NHCH2CH2), 2.13 (s, 3H, COCH3), 1.45 (m, 2H, CH2CH2-
CH3), 1.19 (d, 3H, 7.2 Hz, CHCH3), 0.86 (t, 7.6 Hz, CH2CH3). Yield
of 3-propylimino-2-butanone: 5% (conversion of 12, 10%). 1H NMR
(CDCl3, δ, 270 MHz) of 3-propylimino-2-butanone:31b 3.39 (t, 2H, 6.8
Hz, NCH2CH2), 2.35 (s, 3H, COCH3), 1.90 (s, 3H, NCCH3), 1.69 (m,
2H, CH2CH2CH3), 0.96 (t, 3H, 7.0 Hz, CH2CH3). Yield of 5,6-dimethyl-
4,7-diaza-4,6-decadiene: 11% (conversion of 12, 22%). 1H NMR
(CDCl3, δ, 270 MHz) of 5,6-dimethyl-4,7-diaza-4,6-decadiene:31b 3.36
(t, 4H, 7.0 Hz, 2(NCH2CH2)), 2.03 (s, 6H, 2(NCH3)), 1.68 (m, 4H,2-
(CH2CH2CH3)), 0.96 (t, 6H, 2(CH2CH2CH3)). Unidentified decomposi-
tion products gradually appeared for more than 2 days of the reaction.
The reaction of secondary amines was carried out as follows. To a
suspension of pentanonyl-Pt(III) dinuclear complex 3 (0.018 g, 0.02
mmol) in CDCl3 (0.6 mL) was added HNEt2 (0.041 mL, 0.40 mmol)
at room temperature. After the mixture was stirred for 2 h, a yellow
precipitate was formed, which was filtered. The pale yellow filtrate
was analyzed with 1H NMR and GC/MS spectroscopy to confirm Et2-
NCH2CO(CH2)2CH3 as the exclusive conversion product. By using
CHCl2CHCl2 as the internal reference, the quantitative conversion was
confirmed by the 1H NMR spectrum. The yellow precipitate was
confirmed to be the Pt(II) dimeric complex with 195Pt NMR spectros-
The reaction of 12 with triethylamine was carried out for 6 days to
give 3-buten-2-one in 38% yield. 1H NMR (CDCl3, δ, 270 MHz): 6.32
(dd, J ) 18.0 Hz, 10.0 Hz 1H, CH2dCHCOCH3), 6.17 (d, J ) 18.0
Hz, 1H, CHHdCHCOCH3), 5.90 (d, J ) 10.0 Hz, 1H, CHHd
CHCOCH3), 2.27 (s, 3H, CH2dCHCOCH3).
Crystal Structure Determination of 3‚H2O, 7‚0.5C3H4O, 9, 10,
and 12. Yellow crystals of 3‚H2O, 7‚0.5C3H4O, 9, 10, and 12 suitable
for X-ray diffraction analysis were coated with epoxy resin. Diffraction
data of complexes 3‚H2O, 7‚0.5C3H4O, 9, 10, and 12 were collected
on a Bruker SMART 1000 CCD diffractometer by using Mo KR
radiation. All the intensity data were processed by a SAINT plus
program package. The structure solution was performed with the
SHELXTL software package. All non-hydrogen atoms in 3‚H2O,
7‚0.5C3H4O, 9, 10, and 12 were refined anisotropically. For 7‚0.5C3H4O,
1
the elemental analysis, H NMR spectrum, and unit cell volume (39
1
non-hydrogen atoms in the asymmetric unit in V ) 1553.30(18) Å3
and Z ) 2) showed that 0.5 molecule of 2-propyn-1-ol (C3H4O) is also
contained in the crystal lattice; however, the quality of the collected
diffraction data did not allow the atoms to be located and refined.
Therefore, the structure analysis was carried out without the 0.5
molecule of C3H4O. Further details of the crystallographic analysis of
3‚H2O, 7‚0.5C3H4O, 9, 10, and 12 are summarized in Table 5 and the
Supporting Information.
copy in D2O. H NMR (CDCl3, δ, 270 MHz) for 1-diethylamino-2-
pentanone: 3.14 (s, 2H, H1), 2.47 (q, J ) 6.8 Hz, 4H, N(CH2CH3)2),
2.38 (t, J ) 7.5 Hz, 2H, H3), 1.53 (m, J ) 7.1 Hz, 2H, H4), 0.96 (t, J
) 6.8 Hz, 6H, N(CH2CH3)2), 0.85 (t, J ) 7.2 Hz, 3H, H5). MS (EI) for
1-diethylamino-2-pentanone, m/z (relative intensity): 157 (M+, 4), 142
(4), 114 (3), 86 (100), 59 (83).
The same procedure as above was used for the reactions of
complexes 4-6 with HNEt2. The 1H NMR data and the corresponding
MS spectra for the amino-substituted ketones are given in the following.
The reaction with complex 4 gave 1-diethylamino-2-hexanone, which
Supporting Information Available: Full tables of the data
collection parameters, isotropic and anisotropic temperature
factors, and bond distances and angles for 3‚H2O, 7‚0.5C3H4O,
9, 10, and 12. Crystallographic information is also available.
This material is available free of charge via the Internet at
http://pubs.acs.org.
1
1
was confirmed with H NMR and GC/MS spectra. Yield: 100%. H
NMR (CDCl3, δ, 270 MHz): 3.16 (s, 2H, H1), 2.50 (q, J ) 7.0 Hz,
4H, N(CH2CH3)2), 2.53 (t, J ) 7.4 Hz, 2H, H3), 1.51 (m, 2H, H4),
1.26 (m, 2H, H5), 0.98 (t, J ) 7.0 Hz, 6H, N(CH2CH3)2), 0.86 (t, J )
7.3 Hz, 3H, H6). MS (EI) m/z (relative intensity): 171 (M+, 16), 156
(19), 142 (6), 126 (12), 114 (23), 100 (14), 87 (100), 59 (98).
JA0302634
9
J. AM. CHEM. SOC. VOL. 126, NO. 8, 2004 2545