Synthesis of acetimino complexes of Pt(II) and Pt(IV) and the first heteronuclear μ-acetimido complexes

Article abstract of DOI:10.1021/ic060489i

The reactions of [Ag(NH=CMe₂)₂]ClO₄ with cis-[PtCl₂L₂] in a 1:1 molar ratio give cis-[PtCl(NH=CMe₂)(PPh₃)₂]ClO₄ (1cis) or cis-[PtCl(NH=CMe₂)₂(dmso)]ClO₄ (2), and in 2:1 molar ratio, they produce [Pt(NH=CMe₂)₂L ₂](ClO₄)₂ [L = PPh₃ (3), L ₂ = tbbpy = 4,4′-di-tert-butyl-2,2′-dipyridyl (4)]. Complex 2 reacts with PPh₃ (1:2) to give trans-[PtCl(NH=CMe ₂)(PPh₃)₂]ClO₄ (1trans). The two-step reaction of cis-[PtCl₂(dmso)₂], [Au(NH=CMe ₂)(PPh₃)]ClO₄, and PPh₃ (1:1:1) gives [SP-4-3]-[PtCl(NH=CMe₂)(dmso)(PPh₃)]ClO₄ (5). The reactions of complexes 2 and 4 with PhICl₂ give the Pt(IV) derivatives [OC-6-13]-[PtCl₃(NH=CMe₂)₂(dmso)] ClO₄ (6) and [OC-6-13]-[PtCl₂(NH=CMe₂) ₂(dtbbpy)](ClO₄)₂ (7), respectively. Complexes 1cis and 1trans react with NaH and [AuCl(PPh₃)] (1:10:1.2) to give cis- and trans-[PtCl{μ-N(AuPPh₃)=CMe₂}(PPh ₃)₂]ClO₄ (8cis and 8trans), respectively. The crystal structures of 4·0.5Et₂O·0.5Me₂CO and 6 have been determined; both exhibit pseudosymmetry.

Full text of DOI:10.1021/ic060489i

Inorg. Chem. 2006, 45, 5201−5209
Synthesis of Acetimino Complexes of Pt(II) and Pt(IV) and the First
Heteronuclear -Acetimido Complexes
µ
Jose´ Vicente,* Mar´ıa-Teresa Chicote,* Rita Guerrero, and Inmaculada Vicente-Herna´ndez
Grupo de Qu´ımica Organometa´lica, Departamento de Qu´ımica Inorga´nica,
UniVersidad de Murcia, Aptdo. 4021, Murcia, 30071 Spain
Peter G. Jones†
Institut fu¨r Anorganische und Analytische Chemie der Technischen UniVersita¨t,
Postfach 3329, 38023 Braunschweig, Germany
Delia Bautista§
SACE, UniVersidad de Murcia, Aptdo. 4021, Murcia, 30071 Spain
Received March 23, 2006
The reactions of [Ag(NH
(1cis) or cis-[PtCl(NH CMe2)2(dmso)]ClO4 (2), and in 2:1 molar ratio, they produce [Pt(NH
PPh3 (3), L2 tbbpy 4,4 -di-tert-butyl-2,2 -dipyridyl (4)]. Complex 2 reacts with PPh3 (1:2) to give trans-
[PtCl(NH CMe2)(PPh3)2]ClO4 (1trans). The two-step reaction of cis-[PtCl2(dmso)2], [Au(NH CMe2)(PPh3)]ClO4,
and PPh3 (1:1:1) gives [SP-4-3]-[PtCl(NH CMe2)(dmso)(PPh3)]ClO4 (5). The reactions of complexes 2 and 4 with
PhICl2 give the Pt(IV) derivatives [OC-6-13]-[PtCl3(NH CMe2)2(dmso)]ClO4 (6) and [OC-6-13]-[PtCl2(NH CMe2)2-
(dtbbpy)](ClO4)2 (7), respectively. Complexes 1cis and 1trans react with NaH and [AuCl(PPh3)] (1:10:1.2) to give
cis- and trans-[PtCl{µ-N(AuPPh3)dCMe2 (PPh3)2]ClO4 (8cis and 8trans), respectively. The crystal structures of
0.5Et2O 0.5Me2CO and 6 have been determined; both exhibit pseudosymmetry.
d
CMe2)2]ClO4 with cis-[PtCl2L2] in a 1:1 molar ratio give cis-[PtCl(NHdCMe2)(PPh3)2]ClO4
d
dCMe2)2L2](ClO4)2 [L
)
)
)
′
′
d
d
d
d
d
}
4
‚
‚
Introduction
CMe2)2]ClO49 and their use for preparing the first acetimino
Rh(I)9 and Rh(III)10 complexes; an interesting coupling
process between two acetimino ligands was found to occur
Although acetimine, Me2CdNH, can be identified among
the condensation products of acetone and ammonia,1 it
decomposes readily to give acetonine and NH3.2 Its difficult
synthesis3,4 and handling may account for the scarcity of
acetimino complexes reported so far,5-8 none of which has
been obtained using acetimine itself. We have described the
(5) (a) Sellmann, D.; Thallmair, E. J. Organomet. Chem. 1979, 164, 337.
(b) Harman, W. D.; Taube, H. Inorg. Chem. 1988, 27, 3261. (c)
Rappert, T.; Yamamoto, A. Chem. Lett. 1994, 2211. (d) Fischer, E.
O.; Knauss, L. Chem. Ber. 1970, 103, 1262. (e) Czarkie, D.; Shvo, Y.
J. Organomet. Chem. 1970, 280, 123. (f) Wong, K.-Y.; Che, C.-M.;
Li, C.-K.; Chiu, C.-K.; Zhou, Z.-Y.; Mak, T. C. W. J. Chem. Soc.,
Chem. Commun. 1992, 754. (g) Adcock, P. A.; Keene, F. R.; Smythe,
R. S.; Snow, M. R. Inorg. Chem. 1984, 23, 2336. (h) Yeh, W. Y.;
Ting, C. S.; Peng, S. M.; Lee, G. H. Organometallics 1995, 14, 1417.
(i) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organometallics 2000,
19, 5454. (j) Klingebiel, W.; Noltemeyer, M.; Schmidt, H.-G.; Schmidt-
Ba¨se, D. Chem. Ber./Recueil 1997, 130, 753. (k) Aresta, M.; Quaranta,
E.; Dibenedetto, A.; Giannoccaro, P.; Tommasi, I.; Lanfranchi, M.;
Tiripicchio, A. Organometallics 1997, 16, 834. (l) Fornie´s, J.; Casas,
J. M.; Mart´ın, A.; Rueda, A. J. Organometallics 2002, 21, 4560. (m)
Ruiz, J.; Rodr´ıguez, V.; Cutillas, N.; Lo´pez, G. Organometallics 2002,
21, 4912.
8
syntheses of [Au(NHdCMe2)PPh3]ClO4 and [Ag(NHd
* To whom correspondence should be addressed. E-mail: jvs1@um.es
(J.V.); mch@um.es (M.-T.C).
† To whom correspondence regarding the X-ray diffraction study of
complex 6 should be addressed. E-mail: p.jones@tu-bs.de.
§ To whom correspondence regarding the X-ray diffraction study of
complex 4 should be addressed. E-mail: dbc@um.es.
(1) (a) Bradbury, R. B.; Hancox, N. C.; Hatt, H. H. J. Chem. Soc. 1947,
1394. (b) Murayama, K.; Morimura, S.; Amakasu, O.; Toda, T.;
Yamao, E. Nippon Kagaku Zasshi 1969, 70, 324; Chem. Abstr. 1969,
90, 296.
(6) Vicente, J.; Chicote, M.-T.; Abrisqueta, M.-D.; Guerrero, R.; Jones,
P. G. Angew. Chem., Int. Ed. Engl. 1997, 36, 1203.
(7) King, R. B.; Douglas, W. M. Inorg. Chem. 1974, 13, 1339.
(8) Vicente, J.; Chicote, M. T.; Guerrero, R.; Saura-Llamas, I. M.; Jones,
P. G.; Ram´ırez de Arellano, M. C. Chem.sEur. J. 2001, 7, 638.
(2) Findeisen, K.; Heitzer, H.; Dehnicke, K. Synthesis 1981, 702.
(3) Verardo, G.; Giumanini, A. G.; Strazzolini, P.; Poiana, M. Synth.
Commun. 1988, 18, 1501.
(4) Xu, T.; Zhang, J.; Haw, J. F. J. Am. Chem. Soc. 1995, 117, 3171.
10.1021/ic060489i CCC: $33.50
Published on Web 05/28/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 13, 2006 5201

Vicente et al.
8
at a Rh(III) center to give a 2-methyl-2-amino-4-imino-
pentano ligand.10,11
In this paper, we show that [Au(NHdCMe2)PPh3]ClO4
9
and [Ag(NHdCMe2)2]ClO4 can also be used to prepare
acetimino complexes of platinum. The new species here
described include (i) the first cationic mono- and bis-
(acetimino) complexes of Pt(II) (1-5), (ii) the first Pt(IV)
complexes with NHdCR2 ligands (6 and 7), and (iii) the
first heteronuclear µ-acetimido complexes of any metals (8cis
and 8trans). Unfortunately, all attempts, in some of these
complexes, to provoke an intramolecular coupling process
between two acetimino ligands to give a 2-methyl-2-amino-
4-iminopentano ligand were unfruitful.
While this paper was being written, a paper by Natile et
al. has appeared12 describing the synthesis and in vitro
antitumor activity of the first acetimino complexes of
platinum, namely, the cis and trans isomers of [PtX2(NHd
CMe2)2] and [PtX2(NHdCMe2)(NH3)] (X ) Cl, I), in which
the Me2CdNH ligands form from the reaction of coordinated
ammonia with acetone in the presence of KOH. Complexes
of Pt(IV) with a different type of NH-imine [RR′Cd
NOC(Me)dNH (R/R′ ) Cl/Ar, NH2/Ph),13 Ph2CdNC(R)d
NH (R ) Me, Et),14 R′OC(R)dNH (R/R′ ) Me/Ph, Et/Me,
Et/Ph),15 or H2NNdC(R′)C(Me)dNOC(R)dNH (R/R′ )
Me/Ph, Et/Me, Et/Ph)]16 have been obtained by the attack
of various nucleophiles on (nitrile)Pt(IV) complexes.
Although many complexes containing terminal ketimido/
azavinylidene ligands (R2CdN-M/R2CdN)M/) have been
reported,17 those with an acetimido bridging ligand are scarce,
and only homonuclear species have been reported so
far.7,18-24 Nearly as many different synthetic methods as
bridging acetimido complexes have been described, none of
them being of general application. They involve processes
in which the appropriate precursors decompose thermally,21,22
rearrange,20 or react with 2-nitropropane and CO,19 2-bromo-
2-nitrosopropane,7 or Me2CdNCl.23,24
Experimental Section
IR spectroscopy, elemental analyses, and melting point deter-
minations were carried out as described elsewhere.8 Molar con-
ductivities were measured on ca. 5 × 10-4 M acetone solutions
with a Crison Micro CM2200 conductimeter. The expected ranges
for the 1:1 and 1:2 electrolytes have been reported.25 The NMR
spectra were recorded on Bruker Avance 200, 300, or 400 MHz
spectrometers. Chemical shifts are referred to TMS (1H and
13C{1H}) or H3PO4 (31P{1H}). Unless otherwise stated, all reactions
were carried out at room temperature and without special precau-
tions against moisture. CH2Cl2, acetone, and Et2O were distilled
before use from CaH2, KMnO4, and Na/benzophenone, respectively.
Other solvents [n-pentane (Baker) and n-hexane (Scharlau)] and
reagents [PtCl2 (Johnson Matthey), AgClO4, NaH (Aldrich, 60%,
dispersion in mineral oil), PPh3, and Me4NCl (Fluka)] were obtained
from commercial sources and used as received. [Ag(NHdCMe2)2]-
ClO4,9 [Au(NHdCMe2)(PPh3)]ClO4,8 cis-[PtCl2(PPh3)2],26 cis-
(9) Vicente, J.; Chicote, M. T.; Guerrero, R.; Vicente-Herna´ndez, I.; Jones,
P. G. Inorg. Chem. 2003, 42, 7644.
(10) Vicente, J.; Chicote, M. T.; Guerrero, R.; Vicente-Herna´ndez, I.;
AÄ lvarez-Falco´n, M. M. Inorg. Chem. 2006, 45, 181.
29
[PtCl2(dmso)2],27 [AuCl(PPh3)],28 and PhICl2 were prepared
(11) Vicente, J.; Chicote, M. T.; Guerrero, R.; Vicente-Herna´ndez, I.;
AÄ lvarez-Falco´n, M. M.; Jones, P. G. Organometallics 2005, 24, 4506.
(12) Boccarelli, A.; Intini, F. P.; Sasanelli, R.; Sivo, M. F.; Coluccia, M.;
Natile, G. J. Med. Chem. 2006, 49, 829.
(13) Garnovskii, D. A.; Guedes da Silva, M. F. C.; Pakhomova, T. B.;
Wagner, G.; Duarte, M. T.; Frausto da Silva, J. J. R.; Pombeiro, A. J.
L.; Kukushkin, V. Y. Inorg. Chim. Acta 2000, 300, 499.
(14) Garnovskii, D. A.; Kukushkin, V. Y.; Haukka, M.; Wagner, G.;
Pombeiro, A. J. L. Dalton Trans. 2001, 560.
(15) Bokach, N. A.; Kukushkin, V. Y.; Haukka, M.; Frausto da Silva, J. J.
R.; Pombeiro, A. J. L. Inorg. Chem. 2003, 42, 3602.
according to literature methods. [PtCl2(dtbbpy)] was synthesized
by being refluxed in acetone (15 mL), a mixture of PtCl2 (500 mg,
1.88 mmol), and dtbbpy (605 mg, 2.26 mmol) until a yellow
suspension formed, which was removed by filtration, and the solid
was washed with Et2O (3 × 5 mL) and suction dried (88% yield).
Caution: Perchlorate salts of organic cations may be explosive.
Preparations on a larger scale than that reported herein should be
avoided.
(16) Garnovskii, D. A.; Pombeiro, A. J. L.; Haukka, M.; Sobota, P.;
Kukushkin, V. Y. Dalton Trans. 2004, 1097.
(18) (a) Aime, S.; Gervasio, G.; Milone, L.; Rossetti, R.; Stanghellini, P.
L. J. Chem. Soc., Dalton Trans. 1978, 534. (b) Albini, A.; Kisch, H.
J. Organomet. Chem. 1975, 94, 75. (c) Atwood, J. L.; Milton, P. A.;
Seale, S. K. J. Organomet. Chem. 1971, 28, C29. (d) Deeming, A. J.;
Owen, D. W.; Powell, N. I. J. Organomet. Chem. 1990, 398, 299. (e)
Jennings, J. R.; Lloyd, J. E.; Wade, K. J. Chem. Soc. 1965, 5083. (f)
Khare, G. P.; Doedens, R. J. Inorg. Chem. 1976, 15, 86. (g) Richeson,
D. S.; Mitchell, J. F.; Theopold, K. H. J. Am. Chem. Soc. 1987, 109,
5868. (h) Richeson, D. S.; Mitchell, J. F.; Theopold, K. H. Organo-
metallics 1989, 8, 2570. (i) Su¨ss-Fink, G.; Khan, L.; Raithby, P. R. J.
Organomet. Chem. 1982, 228, 179. (j) Weller, F.; Dehnicke, K. Chem.
Ber. 1977, 110, 3935.
(19) Gambino, O.; Gervasio, G.; Rossetti, R.; Stanghellini, P. L. Inorg.
Chim. Acta 1984, 84, 51.
(20) Herrmann, W. A.; Bell, L. K.; Ziegler, M. L.; Pfisterer, H.; Pahl, C.
J. Organomet. Chem. 1983, 247, 39.
(21) Seale, S. K.; Atwood, J. L. J. Organomet. Chem. 1974, 73, 27.
(22) Uhl, W.; Molter, J.; Neumu¨ller, B.; Schmock, F. Z. Anorg. Allg. Chem.
2001, 627, 909.
(23) Weller, F.; Mu¨ller, U. Chem. Ber. 1979, 112, 2039.
(24) Zettler, F.; Hess, H. Chem. Ber. 1977, 110, 3943.
(25) Geary, W. J. Coord. Chem. ReV. 1971, 7, 81.
(26) Jensen, K. A. Z. Anorg. Allg. Chem. 1936, 229, 242.
(27) Price, J. H.; Williamson, A. N.; Schramm, R. F.; Wayland, B. B. Inorg.
Chem. 1978, 17, 2245.
(28) Uso´n, R.; Laguna, A. Organometallic Syntheses; Elsevier: Amsterdam,
1986; 325.3.
(29) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G. Inorg.
Chem. 1997, 36, 5735.
(17) (a) Ferreira, M. J.; Martins, A. M. Coord. Chem. ReV. 2006, 250, 118-
132. (b) Kukushkin, V. Y.; Tudela, D.; Pombeiro, A. J. L. Coord.
Chem. ReV. 1996, 156, 333. (c) Guedes da Silva, M. F. C.; Frausto da
Silva, J. J. R.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 219. (d)
Daniel, T.; Mueller, M.; Werner, H. Inorg. Chem. 1991, 30, 3118. (e)
Feng, S. G.; White, P. S.; Templeton, J. L. Organometallics 1993,
12, 2131. (f) Werner, H.; Daniel, T.; Knaup, W.; Nuernberg, O. J.
Organomet. Chem. 1993, 462, 309. (g) Powell, K. R.; Perez, P. J.;
Luan, L.; Feng, S. G.; White, P. S.; Brookhart, M.; Templeton, J. L.
Organometallics 1994, 13, 1851. (h) Andreu, P. L.; Cabeza, J. A.;
del Rio, I.; Riera, V.; Bois, C. Organometallics 1996, 15, 3004. (i)
Cabeza, J. A.; del Rio, I.; Riera, V. J. Organomet. Chem. 1997, 548,
255. (j) Castarlenas, R.; Esteruelas, M. A.; Gutierrez-Puebla, E.; Jean,
Y.; Lledos, A.; Martin, M.; On˜ate, E.; Tomas, J. Organometallics 2000,
19, 3100. (k) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organo-
metallics 2001, 20, 3283. (l) Guedes da Silva, M. F. C.; Frausto da
Silva, J. J. R.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 219. (m)
Castarlenas, R.; Esteruelas, M. A.; Jean, Y.; Lledos, A.; On˜ate, E.;
Tomas, J. Eur. J. Inorg. Chem. 2001, 2871. (n) Kuznetsov, M. L.;
Nazarov, A. A.; Pombeiro, A. J. L. J. Phys. Chem. A 2005, 109, 8187.
(o) Ferreira, C. M. P.; Guedes da Silva, M. F. C.; Kukushkin, V. Y.;
Frausto da Silva, J. J. R.; Pombeiro, A. J. L. J. Chem. Soc., Dalton
Trans. 1998, 325. (p) Kiplinger, J. L.; Morris, D. E.; Scott, B. L.;
Burns, C. J. Organometallics 2002, 21, 3073. (q) Hou, Z.; Yoda, C.;
Koizumi, T.; Nishiura, M.; Wakatsuki, Y.; Fukuzawa, S.; Takats, J.
Organometallics 2003, 22, 3586. (r) Jantunen, K. C.; Burns, C. J.;
Castro-Rodriguez, I.; Da Re, R. E.; Golden, J. T.; Morris, D. E.; Scott,
B. L.; Taw, F. L.; Kiplinger, J. L. Organometallics 2004, 23, 4682.
5202 Inorganic Chemistry, Vol. 45, No. 13, 2006

Acetimino Complexes of Pt(II) and Pt(IV)
cis-[PtCl(NHdCMe2)(PPh3)2]ClO4 (1cis). [Ag(NHdCMe2)2]-
ClO4 (127 mg, 0.39 mmol) was added to a solution of cis-
[PtCl2(PPh3)2] (312 mg, 0.39 mmol) in CH2Cl2 (20 mL). The
resulting suspension was stirred for 30 min and filtered through
Celite. The filtrate was concentrated (1 mL), and Et2O (25 mL)
was added to give a suspension, which was stirred for 5 min and
filtered. The solid was dried in an oven (70 °C) for 12 h to give
1cis as a colorless powder. Yield: 321 mg, 88%. mp: 254 °C. 1H
NMR (400 MHz, DMSO-d6): δ 1.54 (s, 3H, Me), 2.26 (s, 3H,
Me), 7.23-7.60 (m, 30H, Ph), 10.65 (br, 1H, NH). 31P{1H} NMR
(162 MHz, DMSO-d6): δ 5.2 (d, 2JPP ) 19 Hz, 1JPPt ) 3112 Hz),
14.1 (d, 2JPP ) 19 Hz, 1JPPt ) 3710 Hz). 13C{1H} NMR (50 MHz,
MHz, CDCl3): δ 1.68 (s, 2H, H2O), 1.71 (s, 3H, Me), 2.18 (d, 3H,
4
Me, JHH ) 3 Hz), 7.38-7.54 (m, 15H, Ph), 9.50 (br, 1H, NH).
1
31P{1H} NMR (162 MHz, CDCl3): δ 2.5 (s, JPPt ) 3324 Hz).
13C{1H} NMR (100 MHz, acetone-d6): δ 28.2 (vt, Me, N ) 3 Hz),
29.0 (Me), 126.6 (vd, ipso-C, N ) 64 Hz), 130.2 (vt, meta-C, N )
11 Hz), 133.3 (para-C), 135.3 (vt, ortho-C, N ) 10 Hz), 192.5
(vd, CdN, N ) 8 Hz). IR (cm-1): νNH 3224, νCdN 1660, 1644.
ΛM (Ω-1 cm2 mol-1): 258. Anal. Calcd for C42H46Cl2N2O9P2Pt:
C, 48.01; H, 4.41; N, 2.67. Found: C, 47.79; H, 4.49; N, 2.75.
[Pt(NHdCMe2)2(dtbbpy)](ClO4)2‚H2O (4‚H2O). [Ag(NHd
CMe2)2]ClO4 (343 mg, 1.07 mmol) was added to a suspension of
[PtCl2(dtbbpy)] (259 mg, 0.48 mmol) in CH2Cl2 (80 mL). The
reaction mixture was stirred for 5 h and filtered through Celite.
The filtrate was concentrated under vacuum (1 mL), and Et2O (20
mL) was added to precipitate a colorless solid, which was filtered,
washed successively with CH2Cl2 (2 mL) and Et2O (2 × 5 mL),
and suction dried to give 4‚H2O as a colorless powder. Yield: 265
mg, 70%. mp (dec): 189 °C. 1H NMR (200 MHz, acetone-d6): δ
1.45 (s, 18H, tBu), 2.55 (s, 6H, Me), 2.71 (s, 6H, Me), 2.83 (s, 2H,
H2O), 7.88 (dd, 2H, H5-bpy, 3JHH ) 6 Hz, 4JHH ) 2 Hz), 8.59 (d,
4
DMSO-d6): δ 26.8 (d, Me, JCP ) 7 Hz), 27.8 (s, Me), 127.2 (vt,
2
ipso-C, N ) 130 Hz), 128.2 (d, meta-C, JCP ) 10 Hz), 129.0 (d,
2
4
meta-C, JCP ) 15 Hz), 131.4 (d, para-C, JCP ) 0.2 Hz), 132.1
(d, para-C, 4JCP ) 0.2 Hz), 133.8 (d, ortho-C, 3JCP ) 10 Hz), 134.5
(d, ortho-C, 3JCP ) 10 Hz), 184.3 (s, CdN). IR (cm-1): νNH 3238,
νCdN 1674, νPtCl 306. ΛM: 1cis is insoluble in acetone. Anal. Calcd
for C39H37Cl2NO4P2Pt: C, 51.38; H, 4.09; N, 1.54. Found: C,
51.60; H, 4.14; N, 1.54.
3
4
trans-[PtCl(NHdCMe2)(PPh3)2]ClO4 (1trans). 2‚H2O (65 mg,
0.12 mmol) was added to a solution of PPh3 (65 mg, 0.25 mmol)
in acetone (10 mL). The solution was stirred for 1 h and
concentrated under vacuum (1 mL), and then Et2O (20 mL) was
added. The suspension was filtered, and the solid was dried first
by suction and then in an oven at 60 °C for 24 h to give 1trans as
2H, H6-bpy, JHH ) 6 Hz), 8.74 (d, 2H, H3-bpy, JHH ) 2 Hz),
10.53 (br, 2H, NH). 13C{1H} NMR (50 MHz, acetone-d6): δ 28.44
(Me), 28.54 (Me), 29.94 (CMe3), 36.7 (CMe3), 122.4 (C3-bpy),
125.9 (C5-bpy), 150.7 (C6-bpy), 157.0 (C2-bpy), 167.6 (C4-bpy),
193.9 (CdN). IR (cm-1): νOH 3604, νNH 3231, νCdN 1650, 1621.
Λ
M (Ω-1 cm2 mol-1): 170. Anal. Calcd for C24H40Cl2N4O9Pt: C,
1
a colorless powder. Yield: 95 mg, 87%. mp (dec): 143 °C. H
36.28; H, 5.07; N, 7.05. Found: C, 35.92; H, 4.88; N, 7.06. Crystals
of 4‚0.5Et2O‚0.5Me2CO suitable for an X-ray difraction study were
obtained by the liquid diffusion method using acetone and Et2O.
[SP-4-3]-[PtCl(NHdCMe2)(dmso)(PPh3)]ClO4 (5). [Au(NHd
CMe2)(PPh3)]ClO4 (292 mg, 0.47 mmol) was added to a suspension
of cis-[PtCl2(dmso)2] (200 mg, 0.47 mmol) in acetone (30 mL).
The resulting solution was stirred for 1 h and filtered through Celite.
The filtrate was concentrated to dryness, and the residue was stirred
with Et2O (5 × 20 mL) to remove [AuCl(PPh3)]. The suspension
was filtered, and the off-white solid was suction dried (A, see
Results and Discussion). It was then dissolved in acetone (20 mL),
and a solution of PPh3 (123 mg, 0.47 mmol) in acetone (10 mL)
was added dropwise over a period of 15 min. The solution was
stirred for 1h and concentrated under vacuum to ca. 1 mL, and
then Et2O (20 mL) was added to precipitate a sticky solid. The
solvent was decanted, and the residue was dried under vacuum,
washed with Et2O (2 × 10 mL), and recrystallized from CH2Cl2/
Et2O to give 5 as a colorless powder. Yield: 280 mg, 82%. mp
NMR (300 MHz, DMSO-d6): δ 1.01 (s, 3H, Me), 1.59 (s, 3H,
Me), 7.59-7.68 (m, 30H, Ph), 10.53 (br, 1H, NH). 31P{1H} NMR
(121 MHz, DMSO-d6): δ 19.3 (s, 1JPPt ) 2604 Hz). 13C{1H} NMR
(75 MHz, DMSO-d6): δ 26.0 (Me), 28.2 (Me), 127.0 (vt, ipso-C,
N ) 60 Hz), 129.1 (vt, meta-C, N ) 8 Hz), 131.8 (s, para-C),
134.3 (vt, ortho-C, N ) 8 Hz), 184.4 (CdN). IR (cm-1): νNH 3192,
νCdN 1672, νPtCl 335. ΛM (Ω-1 cm2 mol-1): 106. Anal. Calcd for
C39H37Cl2NO4PPt: C, 51.38; H, 4.09; N, 1.54. Found: C, 51.05;
H, 4.02; N, 1.59.
cis-[PtCl(NHdCMe2)2(dmso)]ClO4‚H2O (2‚H2O). [Ag(NHd
CMe2)2]ClO4 (145 mg, 0.45 mmol) was added to a suspension of
cis-[PtCl2(dmso)2] (190 mg, 0.45 mmol) in CH2Cl2 (30 mL). After
it was stirred for 30 min, the reaction mixture was filtered through
Celite, and the filtrate was concentrated to dryness. The residue
was heated at 70 °C under vacuum for 30 min and dissolved in
CH2Cl2 (2 mL), and then Et2O (20 mL) was added to precipitate a
sticky material. The solvent was decanted, and when the residue
was stirred with Et2O (3 × 20 mL), a colorless solid formed which
was filtered off and suction dried to give 2‚H2O. Yield: 188 mg,
1
(dec): 134 °C. H NMR (200 MHz, CDCl3): δ 1.73 (s, 3H, Me),
3
2.21 (s, 3H, Me), 3.34 (s+d, JHPt ) 16 Hz, 6H, Me2SO), 7.36-
1
77%. mp: 118 °C. H NMR (400 MHz, acetone-d6): δ 2.32 (d,
7.84 (m, 15H, Ph), 9.51 (br, 1H, NH). 31P{1H} NMR (81 MHz,
3H, Me, 4JHH ) 1 Hz), 2.36 (d, 3H, Me, 4JHH ) 1 Hz), 2.58 (s, 3H,
CDCl3): δ 14.7 (s, JPPt ) 3677 Hz). 13C{1H} NMR (50 MHz,
1
3
Me), 2.59 (s, 3H, Me), 2.80 (s, 2H, H2O), 3.47 (s+d, JHPt ) 20
CDCl3): δ 27.5 (Me), 28.6 (Me), 45.0 (Me, dmso), 125.9 (d, ipso-
Hz, 6H, Me, DMSO), 9.95 (br, 2 H, NH). 13C{1H} NMR (75 MHz,
acetone-d6): δ 27.6 (Me), 27.8 (Me), 28.0 (Me), 28.1 (Me), 43.5
C, JC-P ) 65 Hz), 129.2 (d, meta-C, JCP ) 10 Hz), 132.5 (d,
1
3
4
2
para-C, JCP ) 5 Hz), 134.2 (d, ortho-C, JCP ) 10 Hz), 187.8
(CdN). IR (cm-1): νNH 3225, νCdN 1668, 1651, νSdO 1149, νPtCl
303. ΛM (Ω-1 cm2 mol-1): 148. Anal. Calcd for C23H28Cl2NO5-
PPtS: C, 37.97; H, 3.88; N, 1.93; S, 4.41. Found: C, 37.77; H,
3.93; N, 1.95, S, 4.12.
2
(Me, DMSO, JCPt ) 55 Hz), 190.6 (CdN), 191.2 (CdN). IR
(cm-1): νNH 3260, νCdN 1678, νSdO 1190, νPtCl 349. ΛM (Ω-1 cm2
mol-1): 102. Anal. Calcd for C8H22Cl2N2O6PtS: C, 17.78; H, 4.10;
N, 5.18; S, 5.93. Found: C, 17.48; H, 3.72; N, 5.03; S, 6.02.
cis-[Pt(NHdCMe2)2(PPh3)2](ClO4)2‚H2O (3‚H2O). [Ag(NHd
CMe2)2]ClO4 (163 mg, 0.51 mmol) was added to a solution of cis-
[PtCl2(PPh3)2] (200 mg, 0.25 mmol) in CH2Cl2 (25 mL). The
resulting suspension was stirred for 30 min and filtered. The filtrate
was concentrated under vacuum (1 mL), and upon the addition of
Et2O (20 mL), the suspension was filtered, and the solid was washed
with Et2O (2 × 5 mL) and suction dried to give 3 as a colorless
[OC-6-13]-[PtCl3(NHdCMe2)2(dmso)]ClO4 (6). PhICl2 (158
mg, 0.57 mmol) was added to a solution of cis-[PtCl(dmso)(NHd
CMe2)2]ClO4 (2‚H2O) (100 mg, 0.18 mmol) in CH2Cl2 (15 mL).
The resulting solution was stirred for 1 h and filtered through Celite,
and the filtrate was concentrated under vacuum to ca. 1 mL. Et2O
(20 mL) was added; the suspension was filtered, and the solid was
washed with Et2O (2 × 5 mL) and suction dried to give 6 as a pale
1
1
powder. Yield: 253 mg, 96%. mp (dec): 165 °C. H NMR (400
yellow powder. Yield: 90 mg, 82%. mp: 153 °C. H NMR (400
Inorganic Chemistry, Vol. 45, No. 13, 2006 5203

Vicente et al.
MHz, acetone-d6): δ 2.61 (s, 3H, Me), 2.69 (s, 3H, Me), 2.74 (s,
3
3H, Me), 2.77 (s, 3H, Me), 3.83 (s+d, 6H, Me2SO, JHPt ) 14
1
Hz), 9.71 (t, br, 1H, NH, JHN ) 56 Hz), 10.37 (t, br, 1H, NH,
1JHN ) 55 Hz). 13C{1H} NMR (50 MHz, acetone-d6): δ 25.6 (Me),
2
25.8 (Me), 30.3 (Me), 30.7 (Me), 41.4 (Me, DMSO, JCPt ) 28
Hz), 195.4 (CdN), 197.3 (CdN). IR (cm-1): νNH 3232, νCdN 1644,
ν
SdO 1176, νPtCl 377, 351. ΛM (Ω-1 cm2 mol-1): 142. Anal. Calcd
for C8H20Cl4N2O5PtS: C, 16.20; H, 3.40; N, 4.72; S, 5.40. Found:
C, 16.14; H, 3.36; N, 4.60; S, 5.05. Crystals of 6 suitable for an
X-ray diffraction study were obtained by the liquid diffusion method
using acetone and Et2O.
[OC-6-13]-[PtCl2(NHdCMe2)2(dtbbpy)](ClO4)2 (7). PhICl2
(106 mg, 0.39 mmol) was added to a suspension of 4‚H2O (100
mg, 0.13 mmol) in CH2Cl2 (15 mL). After it was stirred for 2 h,
the resulting suspension was filtered. The solid was washed with
Et2O (2 × 5 mL) and suction dried to give 7 as a pale yellow
1
powder. Yield: 88 mg, 80%. mp: 226 °C. H NMR (300 MHz,
t
4
acetone-d6): δ 1.52 (s, 18H, Bu), 2.83 (s+d, 6H, Me, JHPt ) 7
Hz), 2.94 (s, 6H, Me), 8.25 (dd, 2H, H5-bpy, 3JHH ) 9 Hz, 4JHH
)
Figure 1. Crystal structure of complex 4 showing the atom numbering.
Ellipsoids correspond to 50% probability levels. Selected bond lengths (Å)
and angles (deg): Pt(1)-N(1) ) 2.005(4), Pt(1)-N(2) ) 2.012(4), Pt(1)-
N(4) ) 2.014(4), Pt(1)-N(3) ) 2.015(4), N(1)-C(4) ) 1.279(7), N(2)-
C(1) ) 1.273(7); N(1)-Pt(1)-N(2) ) 86.75(18), N(1)-Pt(1)-N(4) )
96.39(17), N(2)-Pt(1)-N(3) ) 96.29(17), N(4)-Pt(1)-N(3) ) 80.54(17).
3 Hz), 8.98 (d+dd, 2H, H6-bpy, 3JHH ) 6 Hz, 3JHPt ) 21 Hz), 9.08
(d, 2H, H3-bpy, JHH ) 3 Hz), 11.11 (br, 2H, NH). 13C{1H}
4
NMR: decomposes in solution. IR (cm-1): νNH 3259, 3137, νCdN
1644, 1621, νPtCl 370. ΛM (Ω-1 cm2 mol-1): 174. Anal. Calcd for
C24H38Cl4N4O8Pt: C, 34.01; H, 4.52; N, 6.61. Found: C, 34.00;
H, 5.00; N, 6.76.
3
PtPPh3, N ) 11 Hz), 129.7 (d, meta-C, AuPPh3, JCP ) 12 Hz),
131.6 (s, para-C, PPh3), 132.5 (d, para-C, 4JCP ) 2 Hz), 133.7 (d,
ortho-C, AuPPh3, 2JCP ) 13 Hz), 134.8 (vt, ortho-C, PtPPh3, N )
12 Hz), 179.4 (CdN). IR (cm-1): νCdN 1632. ΛM (Ω-1 cm2 mol-1):
116. Anal. Calcd for C57H51AuCl2NO4P3Pt: C, 49.98; H, 3.75;
N, 1.02. Found: C, 49.97; H, 3.79; N, 1.09.
X-ray Structure Determinations of 4‚0.5Et2O‚0.5Me2CO and
6. Figures 1 and 2 show the ellipsoid representations, and Table 1
gives a summary of crystallographic data. The crystals were
mounted in inert oil on a glass fiber and transferred to the cold
stream of the diffractometer (Bruker SMART Apex for 4 and Bruker
SMART 1000 CCD for 6). Absorption corrections were applied
using the program SADABS. The structures were refined aniso-
tropically on F2 (SHELXL, G. M. Sheldrick, University of
Go¨ttingen, Germany). Hydrogen atoms were included as follows:
NH hydrogens refined freely with N-H distance restraints (“SADI”),
methyls as rigid groups, others riding.
Special Features of 4. The acetone and ether of solvation are
each disordered over an inversion center. The hydrogen atoms of
the acetone were not included in the refinement. Compound 4
exhibits pseudosymmetry. The near-equality of the triclinic b and
c axes and â and γ angles means that a C-centered metrically
monoclinic cell may be generated. The structure can be solved and
refined in this cell [a ) 21.4738(8) Å, b ) 13.2669(5) Å, c )
12.0762(5) Å, R ) 90.406(1)°, â ) 100.404(1)°, γ ) 90.348(1)°]
with a C2/m space group. However, there are several anomalies.
The monoclinic R and γ angles differ appreciably from 90°, and
the R values (Rint ) 0.0771, R2 ) 0.0960, and R1 ) 0.0452) are
significantly worse than in the triclinic case. For this reason, we
prefer the triclinic description. However, unambiguous proof of the
correct symmetry is probably impossible to obtain.
Special Features of 6. We thank a referee for suggesting that
we should comment in more detail on the pseudosymmetry of this
compound. For a large fraction of the structure, the atoms can be
grouped into pairs for which the atoms are related by a translation
of 0.5 in x (reflections with h odd are very weak), and this halved
structure can be solved and refined down to acceptable R values
(R2 ) ca. 8%). However, difference peaks of ca. 2-3 e/Å3 are
observed in the perchlorate and DMSO groups, and the U values
cis-[PtCl{µ-N(AuPPh3)dCMe2}(PPh3)2]ClO4 (8cis). Dry CH2Cl2
(25 mL) and THF (20 mL) were successively added to a flask
previously charged, under nitrogen, with 1cis (80 mg, 0.09 mmol),
[AuCl(PPh3)] (52 mg, 0.10 mmol) and NaH (60% dispersion in
mineral oil, 35 mg, 0.9 mmol), and the reaction mixture was
refluxed for 5 h under nitrogen. After it was cooled to room
temperature, the mixture was filtered in air through anhydrous
MgSO4. The filtrate was concentrated under vacuum to ca. 1 mL,
and Et2O (20 mL) added to precipitate 8cis as a cream-colored solid
which was filtered off and suction dried. Yield: 103 mg, 84%.
1
mp: 161 °C. H NMR (300 MHz, CDCl3): δ 1.68 (s, 3H, Me),
2.26 (s, 3H, Me), 7.10-7.54 (m, 45H, Ph). 31P{1H} NMR (121
MHz, CDCl3): δ 6.6 (d, 2JPP ) 20 Hz, 1JPPt ) 2738 Hz), 16.9 (d,
1
2JPP ) 20 Hz, JPPt ) 4014 Hz), 30.0 (s, AuPPh3). 13C{1H} NMR
4
4
(100 MHz, CDCl3): δ 34.0 (dd, Me, JCP ) 8 Hz, JCP ) 4 Hz),
34.6 (d, Me, 4JCP ) 12 Hz), 128.1 (d, meta-C, 3JCP ) 11 Hz), 128.5
(d, meta-C, 3JCP ) 11 Hz), 129.6 (d, meta-C, 3JCP ) 12 Hz), 130.9
(d, para-C, 4JCP ) 2 Hz), 131.91 (para-C), 132.4 (d, para-C, 4JCP
2
) 2 Hz), 133.8 (d, ortho-C, JCP ) 13 Hz), 134.1 (dd, ortho-C,
4
2
2JCP ) 24 Hz, JCP ) 10 Hz), 134.7 (d, ortho-C, JCP ) 10 Hz),
178.5 (d, CN, 3JCP ) 3 Hz). IR (cm-1): νCdN 1639, νPtCl 320. ΛM
(Ω-1 cm2 mol-1): 130. Anal. Calcd for C57H51AuCl2NO4P3Pt: C,
49.98; H, 3.75; N, 1.02. Found: C, 49.68; H, 3.87; N, 1.03.
trans-[PtCl{µ-N(AuPPh3)dCMe2}(PPh3)2]ClO4 (8trans). Dry
CH2Cl2 (40 mL) was added to a Carius tube previously charged,
under nitrogen, with 1trans (125 mg, 0.14 mmol), NaH (60%
dispersion in mineral oil, 65 mg, 1.6 mmol), and [AuCl(PPh3)] (74
mg, 0.15 mmol), and the mixture was heated at 70 °C for 6 h.
After it was cooled to room temperature, the mixture was filtered
in air through Celite, and the filtrate was concentrated under vacuum
to ca. 1 mL. Upon addition of Et2O (20 mL), 8trans precipitated
as a cream-colored powder which was filtered off and suction dried.
1
Yield: 118 mg, 62%. mp: 152 °C. H NMR (400 MHz, CDCl3):
δ 1.27 (s, 3H, Me), 1.57 (s, 3H, Me), 7.11-7.74 (m, 45H, Ph).
31P{1H} NMR (162 MHz, CDCl3): δ 19.5 (PPt, 1JPPt ) 2847 Hz),
27.5 (s, PAu). 13C{1H} NMR (100 MHz, CDCl3): δ 34.5 (Me),
35.1 (d, Me, 4JCP(Au) ) 8 Hz), 127.7 (d, ipso-C, AuPPh3, 1JCP ) 62
Hz), 127.9 (vt, ipso-C, PtPPh3, N ) 57 Hz), 128.7 (vt, meta-C,
5204 Inorganic Chemistry, Vol. 45, No. 13, 2006

Acetimino Complexes of Pt(II) and Pt(IV)
Table 1. Crystal Data for Compounds 4‚0.5Et2O‚0.5Me2CO and 6
4‚0.5Et2O‚0.5Me2CO
27.5H46Cl2N4O9Pt
6
formula
cryst size (mm3)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C
C8H20Cl4N2O5PtS
0.30 × 0.25 × 0.15
monoclinic
P21/c
14.3033(8)
10.4115(6)
25.5757(14)
90
105.820(4)
90
3664.4(4)
8
0.30 × 0.15 × 0.14
triclinic
P1h
12.0737(7)
12.5843(8)
12.6521(8)
63.420(2)
81.402(2)
80.928(2)
1690.87(18)
2
Z
F
MF
calcd (Mg/m3)
1.655
842.67
2.151
593.21
T (K)
100(2)
133(2)
F(000)
846
4.361
1.81-26.37
semiempirical
from equivalents
18 512
2272
8.372
1.48-30.19
semiempirical
from equivalents
69 312
µ(Mo KR) (mm-1
θ range (deg)
abs correction
)
reflns collected
independent reflns
Rint
6854
0.0283
10 221
0.0297
completeness (%)
transm
99.4 (θ ) 26.00°)
0.5803/0.3545
6854/76/445
1.166
95.4 (θ ) 30.00°)
0.367/0.213
10221/6/404
1.087
data/restraints/params
Figure 2. Crystal structure of complex 6 showing the atom numbering.
Ellipsoids correspond to 30% probability levels. Selected bond lengths (Å)
and angles (deg): Pt(1)-N(12) ) 2.037(3), Pt(1)-N(11) ) 2.063(3), Pt(2)-
N(22) ) 2.045(3), Pt(2)-N(21) ) 2.056(3), Pt(1)-Cl(11) ) 2.3159(8),
Pt(1)-Cl(12) ) 2.3224(8), Pt(1)-Cl(13) ) 2.3189(8), Pt(2)-Cl(21) )
2.3169(9), Pt(2)-Cl(22) ) 2.3245(9), Pt(2)-Cl(23) ) 2.3117(8), Pt(1)-
S(1) ) 2.3200(8), Pt(2)-S(2) ) 2.3168(8), N(11)-C(13) ) 1.280(4),
N(12)-C(16) ) 1.278(4), N(21)-C(23) ) 1.284(4), N(22)-C(26) )
1.285(4), S(1)-O(1) ) 1.455(2), S(2)-O(2) ) 1.445(3); N(12)-Pt(1)-
N(11) ) 90.48(11), N(22)-Pt(2)-N(21) ) 88.55(11), N(11)-Pt(1)-Cl(11)
) 91.64(8), N(21)-Pt(2)-Cl(21) ) 92.50(8), N(11)-Pt(1)-Cl(13) )
84.24(8), N(21)-Pt(2)-Cl(23) ) 83.96(8), N(11)-Pt(1)-Cl(12) ) 95.46(8),
N(21)-Pt(2)-Cl(22) ) 96.60(8), N(12)-Pt(1)-Cl(13) ) 85.07(8), N(22)-
Pt(2)-Cl(23) ) 84.52(8), N(12)-Pt(1)-Cl(12) ) 92.33(8), N(22)-Pt(2)-
Cl(22) ) 93.95(8), N(12)-Pt(1)-S(1) ) 88.17(8), N(22)-Pt(2)-S(2) )
89.73(8), Cl(13)-Pt(1)-Cl(11) ) 89.19(3), Cl(23)-Pt(2)-Cl(21) ) 90.40(3),
Cl(11)-Pt(1)-Cl(12) ) 93.42(3), Cl(21)-Pt(2)-Cl(22) ) 91.10(4), Cl(11)-
Pt(1)-S(1) ) 89.51(3), Cl(21)-Pt(2)-S(2) ) 88.78(3), Cl(13)-Pt(1)-
S(1) ) 93.85(3), Cl(23)-Pt(2)-S(2) ) 91.12(3), S(1)-Pt(1)-Cl(12) )
86.40(3), S(2)-Pt(2)-Cl(22) ) 88.28(3).
GOF on F2
final R indices [I > 2s(I)]
R1 ) 0.0362,
R2 ) 0.0838
R1 ) 0.0390
R2 ) 0.0850
2.790 and
-1.441
R1 ) 0.0239
R2 ) 0.0518
R1 ) 0.0354
R2 ) 0.0567
1.460 and
-0.935
R indices (all data)
largest diff. peak
and hole (e.Å-3)
wavelength (Å)
index ranges
0.71073
0.71073
-14 e h e 14
-15 e k e 15
-15 e l e 15
full-matrix
least-squares on F2
-19 e h e 20
-14 e k e 14
-35 e l e 35
full-matrix
least-squares on F2
refinement method
acetimino ligands, one of which occupies a vacant position
at the Pt center to give 1cis. Complex 2 results from the
additional substitution of the labile DMSO trans to the chloro
ligand by the second imine present in solution. Under the
same reaction conditions, [PtCl2(dtbbpy)] and [Ag(NHd
CMe2)2]ClO4 gave [PtCl(NHdCMe2)(dtbbpy)]ClO4 contami-
nated with [Pt(NHdCMe2)2(dtbbpy)](ClO4)2 (4, see below)
and another impurity that we could not identify. We failed
not only to separate this mixture but also in two other
attempts to isolate the monoimino complex.30 Thus, the
reaction of [PtCl2(dtbbpy)] with [Au(NHdCMe2)(PPh3)]ClO4
(1:1, 45 min, DMSO; no reaction occurs in CH2Cl2) and that
of 4‚H2O with QCl (Q ) PPN ) Ph3PdNdPPh3, 1:1, 2 h;
Me4N, 1:1.2, 12 h) gave the desired [PtCl(NHdCMe2)-
of the perchlorate O and DMSO C and O are high. It is possible
that these groups are disordered in the smaller cell, but we prefer
the larger cell without disorder. The basic ADDSYM command in
the program PLATON (A. L. Spek, University of Utrecht,
Netherlands) suggests halving the cell, but its EXACT symmetry
analysis does not. It is probable that, without a detailed experimental
assessment of the weak reflections, the two models cannot be
distinguished with absolute confidence.
Results and Discussion
1
(dtbbpy)]ClO4 (by H and 31P NMR) as the major product,
Synthesis of Acetimino Pt(II) and (IV) Complexes. The
acetimino Pt(II) complexes, 1-5 (Scheme 1), were obtained
by transmetalation of acetimine from [Ag(NHdCMe2)2]ClO4
or [Au(NHdCMe2)PPh3]ClO4 to the appropriate precursor
cis-[PtCl2L2] (L ) PPh3, DMSO; L2 ) dtbbpy). The results
depend on the transmetalating agent, the nature of the L
ligands, and the molar ratio used. When equimolar amounts
of [Ag(NHdCMe2)2]ClO4 and cis-[PtCl2L2] were used,
complexes cis-[PtCl(NHdCMe2)(PPh3)2]ClO4 (1cis) or cis-
[PtCl(NHdCMe2)2(dmso)]ClO4‚H2O (2‚H2O) were obtained
in good yields. The precipitation of AgCl produces two free
but it was mixed with other products ([AuCl(PPh3)] + [PtCl2-
(dtbbpy)], or PPNClO4, or (NMe4)ClO4 + (NMe4)Cl, re-
spectively) that we could not separate.
Two equivalents of [Ag(NHdCMe2)2]ClO4 react with cis-
[PtCl2L2] to give cis-[Pt(NHdCMe2)2L2](ClO4)2‚H2O [L )
t
(30) 1H NMR (200 MHz, CDCl3): δ 1.43 (s, 9H, Me, Bu), 1.47 (s, 9H,
tBu), 2.49 (s, 3H, Me), 2.60 (s, 3H, Me), 7.61 (dd, 1H, H5 or 5′, 3JHH
4
3
4
) 6 Hz, JHH ) 3 Hz), 7.68 (dd, 1H, H5 or 5′, JHH ) 6 Hz, JHH
)
3 Hz), 8.19 (d, 1H, H6 or H6′, 4JHH ) 3 Hz), 8.21 (d 1H, H6 or H6′,
4JHH ) 3 Hz), 8.79 (d, 1H, H3 or H3′, 3JHH ) 6 Hz), 9.28 (d, 1H, H3
3
or H3′, JHH ) 6 Hz), 10.53 (br, 1H, NH).
Inorganic Chemistry, Vol. 45, No. 13, 2006 5205

Vicente et al.
Scheme 1
ClO4 (1:1), (iii) PPNCl (1:1), and (iv) PPh3 (1:1 and 1:2).
The aim of these reactions was to coordinate additional
acetimino ligands to platinum (i and ii) or to see which of
the three different ligands present in 2 is more labile toward
its substitution by chloro (iii) or phosphine ligands (iv).
Unfortunately 2‚H2O does not react with [Au(NHdCMe2)-
(PPh3)]ClO4 and gives unresolvable mixtures upon reacting
with [Ag(NHdCMe2)2]ClO4 or with PPNCl. However, the
slow addition of 1 equiv of PPh3 to a solution of 2‚H2O in
acetone led to a mixture of several compounds including 2
and trans-[PtCl(NHdCMe2)(PPh3)2]ClO4 (1trans) among
others (by NMR). The 1:2 reaction between 2‚H2O and PPh3
allowed the synthesis of pure 1trans in good yield after the
replacement of one DMSO and one acetimino ligand by
PPh3. It seems reasonable that upon substitution of the labile
DMSO ligand by PPh3, an intermediate mono(phosphino)
complex formed, in which the PPh3 ligand would strongly
labilize the trans imino ligand, promoting its fast substitution
by another PPh3 ligand to give finally 1trans.
In an attempt to prepare a bis(dmso)acetimino complex,
we reacted cis-[PtCl2(DMSO)2] and [Au(NHdCMe2)PPh3]-
ClO4 (1:1, Scheme 1). The other product [AuCl(PPh3)] was
removed because of its moderate solubility in Et2O and
isolated in almost quantitative yield. The residue (96%
1
yield) was shown by H NMR to be [PtCl(NHdCMe2)-
(dmso)2]ClO4 (A)31 contaminated with a small amount of
[PtCl(NHdCMe2)2(dmso)]ClO4 (2) that we could not sepa-
rate even after repeated recrystallizations. The crude complex
A reacts with PPh3 (1:1) to give [SP-4-3]-[PtCl(NHdCMe2)-
(DMSO)(PPh3)]ClO4 (5) which can also be obtained in
excellent yield by reacting in two steps [PtCl2(dmso)2],
[Au(NHdCMe2)PPh3]ClO4, and PPh3 (1:1:1) as stated in the
Experimental Section. These are new examples of the
increasing use of gold(I) complexes as transmetalating
agents.8,32
The reactions between complexes 2‚H2O or 4‚H2O and
an excess of PhICl2 (1:3) lead to the first (acetimino)Pt(IV)
complexes reported so far, [OC-6-13]-[PtCl3(DMSO)(NHd
CMe2)2]ClO4 (6) or [OC-6-13]-[PtCl2(NHdCMe2)2(dtbbpy)]-
(ClO4)2 (7), respectively (Scheme 2). An excess of PhICl2
was necessary to avoid contamination of the Pt(IV) com-
PPh3 (3‚H2O), L2 ) dtbbpy (4‚H2O)] in good yield. In the
latter case, an excess of the silver complex must be used to
prevent the formation of a mixture of 4 with [PtCl(NHd
CMe2)(dtbbpy)]ClO4 and [PtCl2(dtbbpy)], which we could
not resolve. The analogous reaction between [Ag(NHd
CMe2)2]ClO4 and cis-[PtCl2(dmso)2] led to extensive de-
composition suggesting that the resulting complexes,
[Pt(NHdCMe2)x(dmso)4-x]2+, are unstable in solution.
The 2-methyl-2-amino-4-iminopentano ligand has been
shown to form from the coupling of two acetimino ligands
at a Rh(III) center facilitated by the presence of catalytic or
stoichiometric amounts of various labile ligands.10,11 How-
ever, neither the reaction of 3‚H2O with Ph2CdNH nor those
of 6 with AsPh3, Ph2CdNH, or PPNCl produce, under similar
reaction conditions (1:1, CH2Cl2, 24 h), any detectable (1H
NMR) amount of the condensed amino-imino ligand.
We have studied the reactivity of 2‚H2O toward (i)
[Au(NHdCMe2)(PPh3)]ClO4 (1:1), (ii) [Ag(NHdCMe2)2]-
(31) 1H NMR (200 MHz, acetone-d6): δ 2.42 (d, 3H, Me, 4JHH ) 1.5 Hz),
3
2.62 (s, 3H, Me), 3.69 (s+d, 6H, Me, dmso, JHPt ) 21 Hz), 3.70
(s+d, 6H, Me, dmso, 3JHPt ) 25 Hz), 9.98 (s, 1H, NH)]. Anal. Calcd
for C7H19Cl2NO6PtS2: C, 15.47; H, 3.52; N, 2.58; S, 11.80. Found:
C, 16.07; H, 3.69; N, 2.76; S, 11.20.
(32) (a) Gregory, J.; Ingold, C. K. J. Chem. Soc. B 1969, 276. (b) Bennett,
M. A.; Bhargava, S. K.; Griffiths, K. D.; Robertson, G. B.; Wickra-
masinghe, W. A.; Willis, A. C. Angew. Chem., Int. Ed. Engl. 1987,
26, 258. (c) Vicente, J.; Chicote, M. T.; Jones, P. G. Inorg. Chem.
1993, 32, 4960. (d) Vicente, J.; Chicote, M. T.; Abrisqueta, M. D. J.
Chem. Soc., Dalton Trans. 1995, 497. (e) Vicente, J.; Chicote, M. T.;
Abrisqueta, M. D.; Jones, P. G. Organometallics 1997, 16, 5628. (f)
Vicente, J.; Chicote, M. T.; Abrisqueta, M. D.; Alvarez-Falco´n, M.
M. J. Organomet. Chem. 2002, 663, 40. (g) Contel, M.; Stol, M.;
Casado, M. A.; van Klink, G. P. M.; Ellis, D. D.; Spek, A. L.; van
Koten, G. Organometallics 2002, 21, 4556. (h) Ferrer, M.; Rodriguez,
L.; Rossell, O.; Lima, J. C.; Go´mez-Sal, P.; Mart´ın, A. Organometallics
2004, 23, 5096. (i) Singh, A.; Sharp, P. R. J. Chem. Soc., Dalton Trans.
2005, 2080. (j) Robitzer, M.; Bouamaied, I.; Sirlin, C.; Chase, P. A.;
van Koten, G.; Pfeffer, M. Organometallics 2005, 24, 1756. (k) Bruce,
M. I.; Humphrey, P. A.; Melino, G.; Skelton, B. W.; White, A. H.;
Zaitseva, N. N. Inorg. Chim. Acta 2005, 358, 1453. (l) Singh, A.;
Sharp, P. R. Organometallics 2006, 25, 678.
5206 Inorganic Chemistry, Vol. 45, No. 13, 2006

Acetimino Complexes of Pt(II) and Pt(IV)
Scheme 2
plex mixtures were obtained in all cases, the NMR of which
did not prove the presence of µ-acetimido ligands.
Crystal Structures of [Pt(NHdCMe2)2(dtbbpy)](ClO4)2‚
0.5Et2O‚0.5Me2CO (4‚0.5Et2O‚0.5Me2CO) and cis-[PtCl3-
(DMSO)(NHdCMe2)2]ClO4 (6). The crystal structure of 4‚
0.5Et2O‚0.5Me2CO (Figure 1) shows that the unit cell
contains two [Pt(NHdCMe2)2(dtbbpy)] cations, four per-
chlorate anions, and one molecule each of Et2O and Me2CO.
In the cation, the platinum atom is in a square planar
environment, distorted by the small bite of the tbbpy ligand
and the narrow N(1)-Pt(1)-N(2) bond angle [86.75(18)°]
compared to N(2)-Pt(1)-N(3) and N(1)-Pt(1)-N(4)
[96.29(17) and 96.39(17)°, respectively] which could be
caused by steric repulsion between the hydrogen atoms on
the imino Me groups and those on the 6 and 6′ positions in
the dtbbpy ligand. The imino ligands are planar, mutually
perpendicular, and rotated with respect to the coordination
plane by approximately 70°. The CdN bond distances
[1.273(7) and 1.279(7) Å] are in the range found for the other
structurally characterized acetimino complexes (1.25-1.30
Å).33 Each of the NH hydrogen atoms is involved in a
classical N-H‚‚‚O hydrogen bond with one perchlorate
anion. Additionally, one dtbbpy C-H takes part in a
C-H‚‚‚O hydrogen bond with the other perchlorate anion
(Figure 1).
Scheme 3
The crystal structure of 6 (Figure 2) involves two
independent formula units; the cations [PtCl3(dmso)(NHd
CMe2)2]+ display only small differences in bond distances
and angles, but the DMSO and one acetimino ligand (trans
to Cl) display somewhat different torsion angles: the root-
mean-square (rms) deviation of a fit of all non-H atoms,
except DMSO O and C and the relevant acetimino methyl
C, was 0.06 Å. The platinum atoms display slightly distorted
octahedral enviroments with the chloro ligands in a meridi-
onal disposition and the imines in a cis disposition. The
Pt-N bond distances trans to DMSO [2.063(3) or 2.056(3)
Å] are slightly longer than those trans to chloro [2.037(3)
or 2.045(3) Å], and all of them are longer than those found
in 4‚0.5Et2O‚0.5Me2CO (see above), suggesting that the trans
influence decreases in the series DMSO > Cl > NHdCMe2
≈ dtbbpy. The CdN bond distances [from 1.278(4) to
1.285(4) Å] are similar to those found in 4‚0.5Et2O‚0.5Me2CO
and other acetimino complexes.33 Each of the acetimino
ligands is essentially planar and lies diagonally with respect
to the octahedral planes [the interplanar angles between the
acetimino planes and the central Pt, S, N, N, Cl planes of
the octahedra are 47.3(1) and 46.4(1)° for cation 1 and
47.1(1) and 55.5(1)° for cation 2]. As in 4, each of the NH
hydrogen atoms is involved in a classical N-H‚‚‚O hydrogen
bond with one perchlorate anion, leading to inversion-
symmetric tetramers of 6. Additionally, some methyl hy-
drogen atoms from both the NHdCMe2 and DMSO ligands
participate in intra- and intermolecular C-H‚‚‚O and
C-H‚‚‚Cl hydrogen bonds (see Supporting Information). The
SdO [S(1)-O(1) ) 1.455(2) Å, S(2)-O(2) ) 1.445(3) Å]
and Pt-S [Pt(1)-S(1) ) 2.3200(8) Å, Pt(2)-S(2) )
plexes with the unreacted Pt(II) derivatives. Although both
6 and 7 were isolated in this way as analytically pure
compounds, 7 slowly decomposes in solution, losing chlorine
1
to give 4 as shown by its H NMR spectrum after a few
hours. This prevented the measurement of the 13C NMR
spectrum of 7. In the case of 6, no decomposition was
observed. The attempted oxidation of complexes 1cis, 1trans,
or 4‚H2O by reacting them with PhICl2 gave complex
mixtures that we could not separate.
Synthesis of (µ-acetimido)PtIIAuI Complexes. The reac-
tions of 1cis or 1trans with NaH and [AuCl(PPh3)] (1:10:
1.2) in a mixture of CH2Cl2 and THF (5 h refluxing under
N2) or in CH2Cl2 (5 h at 70 °C) gave the corresponding cis
(8cis) or trans (8trans) isomers, respectively, of the (µ-
acetimido) complex [PtCl{µ-N(AuPPh3)dCMe2}(PPh3)2]-
ClO4 in a good or moderate yield. The replacement of the
+
NH proton in 1cis or 1trans by the isolobal AuPPh3
fragment requires both heating and the use of an excess of
NaH and [AuCl(PPh3)]. When NHEt2 was used instead of
NaH no reaction was observed. Although the formation of
8cis was also detected by NMR in the room-temperature
reactions of 1cis with [Au(acac)(PPh3)] (1:1) or with [{µ3-
O(AuPPh3)3}]ClO4 (1:0.5), the presence of the byproducts
[Pt(acac)(PPh3)2]ClO4 or [Au(PPh3)2]ClO4 and [AuCl(PPh3)],
respectively, which we could not remove completely, made
these reactions unsuitable for the synthesis of 8cis. Reactions
of 1cis with NaH, Tl(acac), nBuLi, Ag2O, Ag2CO3, or
NaOMe were attempted with the aim of producing a
dehydrohalogenation reaction that could give rise to the
[{Pt(PPh3)2}2{µ-NdCMe2}2] complex. Unfortunately, com-
(33) Cambridge Structural Database, version 5.27; Cambridge Crystal-
lographic Data Center: Cambridge, U,K., 2005; www.ccdc.cam.ac.uk.
Inorganic Chemistry, Vol. 45, No. 13, 2006 5207

Vicente et al.
2.3168(8) Å] bond distances are in the ranges reported in
the literature.34
NMR Spectra. The H NMR spectra of complexes 1-8
complexes 8cis and 8trans show a singlet resonance from
the AuPPh3 fragment (8cis, 30.0; 8trans, 27.5 Hz).
Since the JPPt coupling constants are known to increase
1
1
with the decreasing trans influence of the trans ligand,35 the
J values can be used to assign the geometry of the
(phosphino)Pt complexes, on the basis of previously available
data,35,36 and to classify different ligands in a series of trans
influence. Thus, the SP-4-3 geometry has been assigned to
complex 5 because its 1JPPt is almost identical to that found
in cis-[PtCl2(PPh3)2] (3670 Hz). On the other hand, the 1JPPt
values (in Hz) for our complexes with PPh3 trans to Cl [3710
(1cis), 3677 (5), and 4014 (8cis)], trans to Me2CdNH [3112
(1cis) and 3324 (3)], or trans to P [2604 (1trans) and 2847
(8trans)] are similar to those found in other platinum(II)-
related complexes with phosphine, nitrogen-donor, or chloro
ligands and that for the P trans to Me2CdN(AuPPh3) in 8cis
(2738 Hz) is in the range of those trans to P. These values
suggest the following decreasing series of trans influence:
PPh3 ≈ N(AuPPh3)dCMe2 > NHdCMe2 > Cl.
show the resonances expected for the inequivalent acetimino
or µ-acetimido Me groups (see Experimental Section). Only
in complexes 2 and 3 do the Me protons trans to NH give
4
doublets with JHH values of 1-3 Hz similar to those
previously found by us in other acetimino complexes.6,8 In
complex 7, one of the Me resonances (δ 2.83) displays 195Pt
satellites (4JHPt ) 7 Hz). The chemical shifts of these Me
protons are in the intervals of 1.01-1.73 or 2.21-2.94 ppm
and seem to depend on the presence or absence of a PPh3
ligand in their proximity. We have found that, (i) in
complexes without phosphine ligands (2, 4, 6, and 7), the
two observed Me resonances are in the range of 2.34-2.94
ppm, (ii) in complexes bearing only one PPh3 (5) or two
such ligands in a mutually cis disposition (1cis, 3, and 8cis),
only one of the imino Me groups is appreciably shielded
(1.54-1.71 ppm) while the other remains in the 2.18-2.26
ppm range, and (iii) in complexes bearing two mutually trans
PPh3 ligands, both Me resonances appear at low frequency
(1trans, 1.01 and 1.59; 8trans, 1.27 and 1.57 ppm). We
suggest that this effect could be attributed in part to the
anisotropic shielding of the phosphine phenyl rings. The
similar chemical shifts found for the Me protons in com-
plexes 1trans and 8trans, despite the different moieties,
NHdCMe2 and N(AuPPh3)dCMe2, respectively, suggest the
shielding effect of the PPh3 bonded to gold to be at best
limited. The NH protons are observed in the 1H NMR spectra
of complexes 1-7 as broad resonances in the 9.5-11.1 ppm
range. Although two such resonances are expected for
complexes 2 and 6, only one, rather broad, is observed for
2, while 6 displays two 1:1:1 triplets at δ 9.71 and 10.37
ppm (1JHN ) 56.6 and 53.7 Hz) which can be attributed to
coupling to 14N.8
IR Spectra. One (7) or two broad νNH bands of medium
intensity are observed (3130-3260 cm-1) in the IR spectra
of complexes 1-7 and are absent in those of 8cis and 8trans,
as expected after the replacement of the NH hydrogen by
an isolobal “AuPPh3” fragment. The vibrational spectra of
NHdCMe22 itself shows two weak νNH bands (Raman, 3326
and 3260 cm-1) and two νCdN bands (IR, 1658, 1670 sh
cm-1). One (1cis, 1trans, 2, 6, 8cis, and 8trans) or two (3,
4, 5, and 7) medium to intense absorptions in the 1620-
1680 cm-1 region could be attributed to νCdN modes, even
though the number of absorptions in this region seems to
not be related in an obvious manner to the number or
disposition of the acetimino ligands, as we have previously
observed in other acetimino-gold, -silver, and -rhodium(I)
complexes.8,11
The chlorocomplexes, 1, 2, and 5-8 show one or two (6)
medium bands in the 302-377 cm-1 region that we
tentatively assign to νPtCl modes. The energy of these bands
depends on the disposition of the chloro ligand and is found
to increase in the series “νPtCl trans to PPh3” (1cis, 306; 5, 302;
The 13C{1H} NMR spectra show the expected resonances.
The Me carbons appear in the 25.6-35.1 ppm interval, the
highest frequencies corresponding to the µ-acetimido com-
plexes (8cis, 34.0 and 34.6; 8trans, 34.5 and 35.1 ppm).
Some Me resonances split into a doublet (1cis, 2.68; 8cis,
34.6; 8trans: 35.1 ppm), a doublet of doublets (8cis, 34.0
ppm), or an apparent triplet (3, 28.2 ppm) because of the
coupling with the PPh3 ligands. The NdC carbons give a
resonance in the 178.5-197.3 ppm interval, the lowest
frequencies corresponding, as expected, to the µ-acetimido
complexes (8cis, 178.5; 8trans, 179.4 ppm). This shielding
is of 5-6 ppm with respect to their parent complexes, 1cis
and 1trans, respectively.
The 31P{1H} NMR spectra of the complexes 1cis and 8cis
bearing a “Pt(PPh3)2” fragment show two doublets with 2JPP
values of about 20 Hz indicating their cis geometry (see
Experimental Section). These resonances display 195Pt satel-
lites (1cis, 1JPPt ) 3112 and 3710 Hz; 8cis, 1JPPt ) 2738 and
4014 Hz). However, both the monophosphino complex, 5,
and the “trans-Pt(PPh3)2” complexes, 3, 1trans, and 8trans,
display one singlet resonance with 195Pt satellites. In addition,
8cis, 309 cm-1) < “ν
PtCl trans to N(AuPPh3)dCMe2” (8trans, 320
cm-1) < “νPtCl trans to NHdCMe2” (1trans, 335; 2, 349; 6, 351
cm-1) < “νPtCl trans to Cl” (6, 377; 7, 369 cm-1), thus supporting
the trans influence series proposed above on the basis of
NMR data. In the cases where the comparison is possible, it
can be observed that the νPtCl bands appear at slightly higher
frequency for the Pt(IV) complexes than those for the
analogous Pt(II) complexes, although this effect is only
marginal. The presence in the IR spectra of complexes 2, 5,
and 6 of a strong band in the 1149-1190 cm-1 region is
indicative34,37 of the S coordination of the Me2SdO ligand,
as is the case in all the (DMSO)Pt complexes structurally
characterized33 with the single exception of [Pt(S-DMSO)2-
(35) Appleton, T. G.; Bennett, M. A. Inorg. Chem. 1978, 17, 738.
(36) (a) Romerosa, A.; Bergamini, P.; Bertolasi, V.; Canella, A.; Cattabriga,
M.; Gavioli, R.; Man˜as, S.; Mantovani, N.; Pellacani, L. Inorg. Chem.
2004, 43, 905. (b) Lattman, M.; Burns, E. G.; Chopra, S. K.; Cowley,
A. H.; Arif, A. M. Inorg. Chem. 1987, 26, 1926.
(37) Nakamoto, K. Infrared Spectra of Inorganic and Coordination
Compounds; Wiley-Interscience: New York, 1986.
(34) Calligaris, M. Coord. Chem. ReV. 2004, 248, 351.
5208 Inorganic Chemistry, Vol. 45, No. 13, 2006

Acetimino Complexes of Pt(II) and Pt(IV)
(O-DMSO)2](CF3SO3)2.38 The IR of all our cationic com-
plexes show bands characteristic of the perchlorate anion at
around 1100 and 620 cm-1.
and [OC-6-13]-[PtCl3(NHdCMe2)2(DMSO)]ClO4 are the
first acetimino complexes of Pt to be structurally character-
ized.
Conclusions
Acknowledgment. Dedicated to Dr. Jose´-Antonio Abad
on the occasion of his retirement in recognition of his
outstanding contributions to our research group. We thank
Ministerio de Ciencia y Tecnolog´ıa and FEDER for financial
support (CTQ2004-05396) and for a contract to I.V.-H. R.G.
thanks Cajamurcia (Spain) for a grant. We thank the referees
for their contributions to improve this article.
We have found complexes [Ag(NHdCMe2)2]ClO4 and
[Au(NHdCMe2)PPh3]ClO4 to be efficient transmetalating
agents toward [PtCl2(PPh3)2], [PtCl2(DMSO)2], and [PtCl2-
(dtbbpy)]. Their use allowed us to prepare the first cationic
acetimino complexes of Pt(II). The oxidative addition of
chlorine to some (acetimino)Pt(II) complexes to give the
corresponding Pt(IV) derivatives was achieved by use of
PhICl2. The reactions of some (acetimino)Pt(II) complexes
with NaH and [AuCl(PPh3)] produced the first heteronuclear
µ-acetimido complexes of any metals, resulting from the
substitution of the NH proton by the isolobal Au(PPh3)
fragment. [Pt(NHdCMe2)2(dtbbpy)](ClO4)2‚0.5Et2O‚0.5Me2CO
Supporting Information Available: Listing of all refined
and calculated atomic coordinates, anisotropic thermal parameters,
bond lengths and angles, and CIF files for complexes 4 and 6.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(38) Elding, L. I.; Oskårsson, A. Inorg. Chim. Acta 1987, 130, 209.
IC060489I
Inorganic Chemistry, Vol. 45, No. 13, 2006 5209