Kinetic and thermodynamic aspects of the regioselective addition of bifunctional hydroxylaminooxime-type HO-nucleophiles to Pt-complexed nitriles

Article abstract of DOI:10.1021/ic051909r

The coupling between coordinated propiononitriles in trans-[PtCl _n(EtCN)₂] (n = 2, 4) and the 1,2-hydroxylaminooximes HON(H)CMe₂C(R)=NOH (R = Ph 1, Me 2) proceeds smoothly in CHCl ₃ at ca. 40-45°C and gives trans-[PtCl_n-{NH=C(Et)ON(H) CMe₂C(R)=NOH}₂] (n = 2, R = Ph 5, Me 6; n = 4, R = Ph 7, Me 8) in 80-85% isolated yields. The reaction is highly regioselective, and both spectroscopic (IR; FAB⁺-MS; 1D ¹H, ¹³C{ ¹H}, and ¹⁹⁵Pt NMR; and 2D ¹H,¹³C HMQC, ¹H,¹³C HMBC, and ¹H,¹⁵N HMQC NMR) and X-ray data for 6-8 suggest that the addition proceeds exclusively via the hydroxylamine moiety of the 1,2-hydroxylaminooxime species; the existence of an oxime group remote from the nucleophile was also confirmed. Heating of 6 in air leads to its conversion to the unusual nitrosoalkane complex [PtCl ₂{HON=C(Me)C(Me)₂N=O}] (9), whereas in the case of 5, only the metalfree salt [H₃NC(Me)₂C(Ph)=NOH] ₂(NO₃)Cl·H₂O (10) was isolated. To compare the kinetic aspects and trends in the addition of both types of nucleophiles (oximes and hydroxylamines; for the latter, see our recent work: Inorg. Chem. 2005, 44, 2944) to coordinated nitriles, a kinetic study of the addition of HON=C(CH₂Ph)₂ to [Ph₃PCH ₂-Ph][PtCl₅(EtCN)] (11) to give [Ph₃PCH ₂Ph][PtCl₅{NH=C(Et)ON=C(CH₂Ph)₂}] (12) was performed. The calculated rate constant k₂ of 3.9 x 10 ^-6 M^-1 s^-1 at -20°C for the addition of the oxime indicates that the hydroxylamine is, by a factor 1.7 × 10 ⁴, more reactive toward the addition to nitriles than the oxime. Results of the synthetic, kinetic, and theoretical (at the B3LYP level of theory) studies have demonstrated that the high regioselectivity of the reactions of the 1,2-hydroxylaminooximes with ligated nitriles is both kinetically and thermodynamically controlled.

Full text of DOI:10.1021/ic051909r

Inorg. Chem. 2006, 45, 2296−2306
Kinetic and Thermodynamic Aspects of the Regioselective Addition of
Bifunctional Hydroxylaminooxime-type HO-Nucleophiles to
Pt-Complexed Nitriles
Konstantin V. Luzyanin,†,‡ Vadim Yu. Kukushkin,*,‡ Maxim L. Kuznetsov,†,§ Alexander D. Ryabov,|
Markus Galanski, Matti Haukka,# Eugene V. Tretyakov,¶ Victor I. Ovcharenko,¶
Maximilian N. Kopylovich,† and Armando J. L. Pombeiro*,†
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico,
AVenida RoVisco Pais, 1049-001 Lisbon, Portugal, St.Petersburg State UniVersity,
198504 Stary Petergof, Russian Federation, Department of Chemistry, Moscow Pedagogical State
UniVersity, NesVigskiy Pereulok 3, 119021 Moscow, Russian Federation, Department of
Chemistry, Carnegie Mellon UniVersity, 4400 Fifth AVenue, Pittsburgh, PennsylVania 15213,
Institute of Inorganic Chemistry - Bioinorganic, EnVironmental and Radiochemistry, UniVersity of
Vienna, Wa¨hringer Strasse 42, A-1090 Vienna, Austria, Department of Chemistry, UniVersity of
Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland, and International Tomography Center,
Institutskaya Street 3a, 630090 NoVosibirsk, Russian Federation
Received November 4, 2005
The coupling between coordinated propiononitriles in trans-[PtCln(EtCN)2] (n
HON(H)CMe2C(R) NOH (R Ph 1, Me 2) proceeds smoothly in CHCl3 at ca. 40
NH C(Et)ON(H)CMe2C(R) NOH 2] (n 2, R Ph 5, Me 6; n 4, R Ph 7, Me 8) in 80
yields. The reaction is highly regioselective, and both spectroscopic (IR; FAB+-MS; 1D 1H, 13C 1H
NMR; and 2D 1H,13C HMQC, 1H,13C HMBC, and 1H,15N HMQC NMR) and X-ray data for 6
8 suggest that the
)
2, 4) and the 1,2-hydroxylaminooximes
45 C and gives trans-[PtCln-
85% isolated
, and 195Pt
d
)
−
°
{
d
d
}
)
)
)
)
−
{
}
−
addition proceeds exclusively via the hydroxylamine moiety of the 1,2-hydroxylaminooxime species; the existence
of an oxime group remote from the nucleophile was also confirmed. Heating of 6 in air leads to its conversion to
the unusual nitrosoalkane complex [PtCl2
free salt [H3NC(Me)2C(Ph) NOH]2(NO3)Cl
the addition of both types of nucleophiles (oximes and hydroxylamines; for the latter, see our recent work: Inorg.
Chem. 2005, 44, 2944) to coordinated nitriles, a kinetic study of the addition of HON C(CH2Ph)2 to [Ph3PCH2-
Ph][PtCl5(EtCN)] (11) to give [Ph3PCH2Ph][PtCl5 NH C(Et)ON C(CH2Ph)2 ] (12) was performed. The calculated
C for the addition of the oxime indicates that the hydroxylamine
104, more reactive toward the addition to nitriles than the oxime. Results of the synthetic,
{HONdC(Me)C(Me)2NdO}] (9), whereas in the case of 5, only the metal-
d
‚
H2O (10) was isolated. To compare the kinetic aspects and trends in
d
{
d
d
}
6
1
1
rate constant k2 of 3.9
is, by a factor 1.7
× −20 °
10- M- s- at
×
kinetic, and theoretical (at the B3LYP level of theory) studies have demonstrated that the high regioselectivity of
the reactions of the 1,2-hydroxylaminooximes with ligated nitriles is both kinetically and thermodynamically controlled.
Introduction
reviews,1-3 including recent surveys.4-6 In general, the
interest in conversions of nitriles at metal centers stems from
the following possibilities: first, to use nitriles as synthons
Nucleophilic addition to metal-activated RCtN species
is one of the frontier areas of current research on organo-
nitriles, and this topic has been the subject of comprehensive
(1) Kukushkin, V. Yu.; Pombeiro, A. J. L. Chem. ReV. 2002, 102, 1771.
(2) Pombeiro, A. J. L.; Kukushkin, V. Yu. Reactions of Coordinated
Nitriles. In ComprehensiVe Coordination Chemistry, 2nd ed.; Lever,
A. B. P., Ed.; Elsevier: New York, 2004; Vol. 1, Chapter 1.34, pp
639-660.
* To whom correspondence should be addressed. E-mail:
kukushkin@vk2100.spb.edu (V.Yu.K.), pombeiro@ist.utl.pt (A.J.L.P.).
† Instituto Superior Te´cnico.
‡ St.Petersburg State University.
§ Moscow Pedagogical State University.
(3) Michelin, R. A.; Mozzon, M.; Bertani, R. Coord. Chem. ReV. 1996,
| Carnegie Mellon University.
147, 299.
Institute of Inorganic Chemistry - Bioinorganic, Environmental and
Radiochemistry.
(4) Kukushkin, V. Yu.; Pombeiro, A. J. L. Inorg. Chim. Acta 2005, 358,
1.
# University of Joensuu.
(5) Bokach, N. A.; Kukushkin, V. Yu. Uspekhi Khimii (Russ. Chem. ReV.),
¶ International Tomography Center.
2005, 74, 164.
2296 Inorganic Chemistry, Vol. 45, No. 5, 2006
10.1021/ic051909r CCC: $33.50
© 2006 American Chemical Society
Published on Web 01/31/2006

Addition of Hydroxylaminooximes to Pt-Ligated Nitriles
for the preparation of compounds with a broad spectrum of
applications (e.g., phthalocyanines7); second, to provide
environmentally friendly metal-catalyzed hydrolytic trans-
formations of RCN species to amides (e.g., of industrial and
pharmacological significance4); and third, to synthesize, via
the nucleophilic addition, diverse imino complexes (e.g.,
exhibiting antitumor properties8). Regarding the creation of
a C-O bond due to metal-mediated nitrile-nucleo-
phile coupling, the analysis of experimental material col-
lected to date1-6 shows that the largest number of works
in this direction have been focused on the hydration of
RCN species,9 and reactions with alcohols,10 whereas
coupling with HON-type nucleophiles is still a scarcely
explored area.
Figure 1.
i.e., 1,2-hydroxylaminooximes (see boxed compounds in-
Figure 1; IUPAC names 2-hydroxyamino-2-methyl-1-phen-
ylpropan-1-one oxime, 1, and 3-hydroxyamino-3-methyl-
butan-2-one oxime, 2), where the N atoms of the HON
functional groups are in sp3 and sp2 hybridization, respec-
tively. The distinct hybridization should determine different
nucleophilic properties of the HO moieties of the hydroxyl-
aminooxime species.
Following our ongoing project investigating various reac-
tivity modes of complexed organonitriles (i.e., nucleophilic1-2
and electrophilic1-3,11 additions and [2 + 3] dipolar cycload-
ditions12), we extended our previous works on the metal-
mediated hydroxylamine-nitrile13,14 and oxime-nitrile15-22
couplings to such combined bifunctional HO-nucleophiles,
This project, utilizing the model Pt-based system, was
driven primarily by the necessity to shed light on the recently
discovered NiII/HON-nucleophile-promoted conversion of
o-phthalonitriles (I, Scheme 1) to nickel(II) phthalocyanines
(II).23,24 In the case of HON-nucleophiles such as oximes,
this reaction proceeds (route A) via the formation of an
intermediate complex (III) (generated by the double nucleo-
philic addition to a cyano carbon), which, in turn, reacts
further with 2 equiv of o-phthalonitriles to form NiPcs (route
B). The employment of HONR2 species as alternative HON-
nucleophiles (route C) enhances the reactivity to such a
degree that the tetramerization proceeds rapidly in a single
pot and the intermediate similar to III could not be detected.
The difference in promoting abilities of oximes and dialky-
lhydroxylamines toward the formation of phthalocyanines
should be rationalized, and this warrants a separate investiga-
tion.
(6) Kuznetsov, M. L. Uspekhi Khimii (Russ. Chem. ReV.), 2002, 71, 307.
(7) McKeown, N. B. Phthalocyanines. In ComprehensiVe Coordination
Chemistry, 2nd ed.; Lever, A. B. P., Ed.; Elsevier: New York, 2004,
Vol. 1, Chapter 1.24, pp 507-514 and references therein.
(8) Natile, G.; Coluccia, M. Coord. Chem. ReV. 2001, 216-217, 383.
Liu, Y.; Pacifico, C.; Natile, G.; Sletten, E. Angew. Chem., Int. Ed.
2001, 40, 1226. Gonzalez, A. M.; Cini, R.; Intini, F. P.; Pacifico, C.;
Natile, G. Inorg. Chem. 2002, 41, 470. Cini, R.; Caputo, P. A.; Intini,
F. P.; Natile, G. Inorg. Chem. 1995, 34, 1130 and references therein.
(9) Rochon, F. D.; Kong, P. C.; Melanson, R. Inorg. Chem. 1990, 29,
2708. Hiraki, K.; Kinoshita, Y.; Kinoshita-Kawashima, J.; Kawano,
H. J. Chem. Soc., Dalton Trans. 1996, 291. Kukushkin, V. Yu.;
Nishioka, T.; Nakamura, S.; Kinoshita, I.; Isobe, K. Chem. Lett. 1997,
189. Neumann, D.; Paraskevopoulou, P.; Psaroudakis, N.; Mertis, K.;
Staples, R. J.; Stavropoulos, P. Inorg. Chem. 2000, 39, 5530. Bennett,
B. K.; Lovell, S.; Mayer, J. M. J. Am. Chem. Soc. 2001, 123, 4336.
(10) Bokach, N. A.; Kukushkin, V. Yu.; Kuznetsov, M. L.; Garnovskii,
D. A.; Natile, G.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 2041.
(11) Pombeiro, A. J. L.; Hughes, D. L.; Richards, R. L. Chem. Commun.
1988, 1052. Frau´sto da Silva, J. J. R.; Guedes da Silva, M. F. C.;
Henderson, R. A.; Pombeiro, A. J. L.; Richards, R. L. J. Organomet.
Chem. 1993, 461, 141. Pombeiro, A. J. L.; Guedes da Silva, M. F. C.
J. Organomet. Chem. 2001, 617, 65. Guedes da Silva, M. F. C.; Frau´sto
da Silva, J. J. R.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 219.
Cunha, S. M. P. R.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L.
Inorg. Chem. 2003, 42, 2157. Kuznetsov, M. L.; Nazarov, A. A.;
Pombeiro A. J. L. J. Phys. Chem. A 2005, 109, 8187.
(12) Wagner, G.; Pombeiro, A. J. L.; Kukushkin, V. Yu. J. Am. Chem.
Soc. 2000, 122, 3106. Wagner, G.; Haukka, M.; Frau´sto da Silva, J.
J. R.; Pombeiro, A. J. L.; Kukushkin, V. Yu. Inorg. Chem. 2001, 40,
264. Bokach, N. A.; Khripoun, A. V.; Kukushkin, V. Yu.; Haukka,
M.; Pombeiro, A. J. L. Inorg. Chem. 2003, 42, 896. Charmier, M. A.
J.; Kukushkin, V. Yu.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans.
2003, 2540. Kuznetsov, M. L.; Kukushkin, V. Yu.; Dement’ev, A. I.;
Pombeiro, A. J. L. J. Phys. Chem., A, 2003, 107, 6108. Bokach, N.
A.; Kukushkin, V. Yu.; Haukka, M.; Pombeiro, A. J. L. Eur. J. Inorg.
Chem. 2005, 845.
Further interests in the project are at least three-fold: (i)
to study the regioselectivity of the addition of 1 and 2 and
to verify preferences in the C-O bond formation; (ii) to
investigate, by theoretical methods, thermodynamic aspects
of the regioselectivity of the addition; and (iii) to study
quantitatively the relative nucleophilicities of oximes and
hydroxylamines toward RCN species bound to a Pt center
in order to understand kinetic aspects and trends in their
addition to coordinated nitriles. The scenario of our work,
described in this article, follows these lines.
(17) Kukushkin, V. Yu.; Pakhomova, T. B.; Bokach, N. A.; Wagner, G.;
Kuznetsov, M. L.; Galanski, M.; Pombeiro, A. J. L. Inorg. Chem.
2000, 39, 216.
(18) Garnovskii, D. A.; Guedes da Silva, M. F. C.; Pakhomova, T. B.;
Wagner, G.; Duarte, M. T.; Frau´sto da Silva, J. J. R.; Pombeiro, A. J.
L.; Kukushkin, V. Yu. Inorg. Chim. Acta 2000, 300-302, 499.
(19) Kuznetsov, M. L.; Bokach, N. A.; Kukushkin, V. Yu.; Pakkanen, T.;
Wagner, G.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans. 2000,
4683.
(20) Bokach, N. A.; Haukka, M.; Pombeiro, A. J. L.; Morozkina, S. N.;
Kukushkin, V. Yu. Inorg. Chim. Acta 2002, 336, 95.
(21) Makarycheva-Mikhailova, A. V.; Haukka, M.; Bokach, N. A.; Gar-
novskii, D. A.; Galanski, M.; Keppler, B. K.; Pombeiro, A. J. L.;
Kukushkin, V. Yu. New J. Chem. 2002, 26, 1085.
(13) Wagner, G.; Pombeiro, A. J. L.; Kukushkin, Yu. N.; Pakhomova, T.
B.; Ryabov, A. D.; Kukushkin, V. Yu. Inorg. Chim. Acta 1999, 292,
272. Luzyanin, K. V.; Kukushkin, V. Yu.; Kuznetsov, M. L.;
Garnovskii, D. A.; Haukka, M.; Pombeiro, A. J. L. Inorg. Chem. 2002,
41, 2981. Luzyanin, K. V.; Kukushkin, V. Yu.; Haukka, M.; Frau´sto
da Silva, J. J. R.; Pombeiro, A. J. L. Dalton Trans. 2004, 2727.
(14) Luzyanin, K. V.; Kukushkin, V. Yu.; Ryabov, A. D.; Haukka, M.;
Pombeiro, A. J. L. Inorg. Chem. 2005, 44, 2944.
(15) Kukushkin, V. Yu.; Pakhomova, T. B.; Kukushkin, Yu. N.; Herrmann,
R.; Wagner, G.; Pombeiro, A. J. L. Inorg. Chem. 1998, 37, 6511.
(16) Kukushkin, V. Yu.; Ilichev, I. V.; Wagner, G.; Frau´sto da Silva, J. J.
R.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans. 1999, 3047.
Wagner, G.; Pombeiro, A. J. L.; Bokach, N. A.; Kukushkin, V. Yu.
J. Chem. Soc., Dalton Trans. 1999, 4083.
(22) Luzyanin, K. V.; Haukka, M.; Izotova, Yu. A.; Kukushkin, V. Yu.;
Pombeiro, A. J. L. Acta Crystallogr. E 2005, 61, m1765.
(23) Pombeiro, A. J. L.; Kopylovich M. N.; Kukushkin V. Yu.; Luzyanin,
K. V. Patent Pending, PAT-103130Y, Portugal, Jun 2004.
(24) Kopylovich, M. N.; Kukushkin, V. Yu.; Haukka, M.; Luzyanin, K.
V.; Pombeiro, A. J. L. J. Am. Chem. Soc. 2004, 126, 15040.
Inorganic Chemistry, Vol. 45, No. 5, 2006 2297

Luzyanin et al.
Scheme 1
Results and Discussion
CMe2C(R)dNOH, with R ) Ph (1), Me (2) (in the synthetic
experiment, 2 was used as the monoacetate salt, 2‚MeCO2H),
proceeds smoothly in CHCl3 at ca. 40-45 °C via routes E
and F, Scheme 2, and the subsequent workup provides the
new PtII and PtIV-imino species trans-[PtCln{NHdC(Et)ON-
(H)CMe2C(R)dNOH}2] (n ) 2, R ) Ph 5, Me 6; n ) 4, R
) Ph 7, Me 8) in good isolated yields (80-85%). The
reaction is highly regioselective, and both spectroscopic and
X-ray data (see later) suggest that the addition proceeds
exclusively via the hydroxylamine moiety of the 1,2-
hydroxylaminooxime species.
Platinum-Mediated Coupling of Nitriles with 1,2-
Hydroxylaminooximes. Despite certain progress in metal-
mediated nitrile-nucleophile coupling, relatively few inves-
tigations have been carried out with the addition of potentially
bifunctional nucleophiles to the nitrile C atom. Among the
latter, attention should be drawn to the coupling between
metal-complexed nitriles and bifunctional nucleophiles bear-
ing the same (e.g., diphosphines,25 dioximes,17,26 and di-
amines27) and different (amino alcohols,28 salicylaldoximes,20
mixed sulfimide/sulfides,29 hydroxy/phosphines,30 and oxime/
hydrazones31) nucleophilic sites. 1,2-Hydroxylaminooximes
(1 and 2) are bifunctional HO-nucleophiles insofar as both
N and O atoms from the hydroxylamine NHOH moiety and
O atom from the oxime CdNOH group exhibit nucleophilic
properties;13-22 their reactions with and the regioselectivity
of their addition to complexed nitriles have not been studied
to date.
It is well-known that alkyl hydroxylamines are much
stronger N-bases than oximes, e.g., protonation of the N atom
of oximes occurs at the Hammet acidity (H0) range from
-1.75 to +0.61,32 whereas for MeNHOH, the pKa is 5.96
in water.33 This significant difference in basicity allows the
protonation of 1,2-hydroxylaminooximes to occur exclusively
at the hydroxylamino group, leaving the oxime functionality
intact. We attempted to control the addition of the 1,2-
hydroxylaminooxime species to complexed nitriles and
performed the reaction of 3 and 4 with 2‚MeCO2H (or with
2‚MeCO2H in the presence of added CF3CO2H in the amount
of 1 mmol). In doing so, we observed that, although
protonation of the hydroxylamine function provokes a
significant decrease of the reactivity of this nucleophilic
center, the reaction still remains highly regioselective and
the addition proceeds exclusively via the same hydroxyl-
amine moiety.
We have now found that the coupling between Pt-bound
nitriles in 3 and 4 and 1,2-hydroxylaminooximes HON(H)-
(25) Cotton, F. A.; Daniels, L. M.; Murillo, C. A.; Wang, X. Polyhedron
1998, 17, 2781.
(26) Pavlishchuk, V. V.; Kolotilov, S. V.; Addison, A. W.; Prushan, M.
J.; Butcher, R. J.; Thompson, L. K. Inorg. Chem. 1999, 38, 1759.
Pavlishchuk, V. V.; Kolotilov, S. V.; Addison, A. W.; Prushan, M.
J.; Butcher, R. J.; Thompson, L. K. Chem. Commun. 2002, 468.
(27) Kukushkin, Yu. N.; Kiseleva, N. P.; Zangrando, E.; Kukushkin, V.
Yu. Inorg. Chim. Acta 1999, 285, 203. Rousselet, G.; Capdevielle,
P.; Maumy, M. Tetrahedron Lett. 1993, 34, 6395. Syamala, A.;
Chakravarty, A. R. Inorg. Chem. 1991, 30, 4699. Maresca, L.; Natile,
G.; Intini, F. P.; Gasparrini, F.; Tiripicchio, A.; Tiripicchio-Camellini,
M. J. Am. Chem. Soc. 1986, 108, 1180.
(28) Makarycheva-Mikhailova, A. V.; Kukushkin, V. Yu.; Nazarov, A. A.;
Garnovskii, D. A.; Pombeiro, A. J. L.; Haukka, M.; Keppler, B. K.;
Galanski, M. Inorg. Chem. 2003, 8, 2805.
(29) Makarycheva-Mikhailova, A. V.; Selivanov, S. I.; Bokach, N. A.;
Kukushkin, V. Yu.; Kelly, P. F.; Pombeiro, A. J. L. Russ. Chem. Bull.,
Int. Ed. 2004, 8, 1681.
It is worth noting that the coupling of propiononitrile in 3
or 4 with 1 or 2‚MeCO2H is metal-mediated insofar as the
reaction of free EtCN with 1,2-hydroxylaminooximes in
CHCl3 does not occur under the same conditions for even 2
days.
(30) Ang, H.-G.; Koh, C.-H.; Koh, L.-L.; Kwik, W.-L.; Leong, W.-K.;
Leong, W.-Y. J. Chem. Soc., Dalton Trans. 1993, 847.
(31) Garnovskii, D. A.; Pombeiro, A. J. L.; Haukka, M.; Sobota, P.;
Kukushkin, V. Yu. Dalton Trans. 2004, 1097.
(32) Lesz, K.; Sykulski, J. Roczniki Chem. 1977, 51, 2445; Chem. Abstr.
1978, 88, 169415.
(33) Bissot, T. C.; Parry, R. W.; Campbell, D. H. J. Am. Chem. Soc. 1957,
4, 796.
2298 Inorganic Chemistry, Vol. 45, No. 5, 2006

Addition of Hydroxylaminooximes to Pt-Ligated Nitriles
Scheme 2
Table 1. Selected NMR Chemical Shifts for Complexes 5-8
1H 13C
Characterization of Imino Complexes 5-8. Compounds
5-8 gave satisfactory C, H, and N elemental analyses. Their
FAB-MS, IR, and 1D (1H, 13C{1H}, and 195Pt) and 2D (1H,13C
HMQC, H,13C HMBC, and H,15N HMQC) NMR spectra
are in good agreement with the proposed structures of PtII
and PtIV complexes with the newly formed imino ligands
HNdC(Et)ON(H)CMe2C(R)dNOH, the latter derived from
the regioselective nitrile-hydroxylamine coupling of the 1,2-
hydroxylaminooximes.
195Pt
complex
Pt-NH
N-OH
Pt-NdC
CdNOH
1
1
5
6
7
8
8.18
8.16
9.14
9.06
9.84
10.68
9.39
175.6
177.0
179.5
179.5
159.9
157.9
160.8
157.1
-2027
-2031
-153
-92
10.81
of the metal center and the coupling of hydroxylamine versus
oxime moieties can best be judged on the basis of significant
shift differences and two-dimensional heteronuclear cor-
related NMR techniques.
The FAB+-MS spectra of 5-8 display molecular ion peaks
and/or a characteristic fragmentation for [PtCln(imine)2]
compounds, corresponding to the loss of Cl’s from the
molecular ion, viz., [M - nCl]+; these data agree well with
those observed for the previously characterized platinum
imino complexes.13-15,17-22 In the IR spectra, 5-8 give no
bands from ν(CtN) stretching vibrations in the range
between 2400 and 2270 cm-1 {such bands appear at 2340
cm-1 (vs) for trans-[PtCl4(EtCN)2]34 and 2314 cm-1 (m) for
trans-[PtCl2(EtCN)2]35} but show one (for 5, 7, 8) or two
(for 6) intense bands in the range of 1660-1595 cm-1
assigned to ν(CdN) of the newly formed imino group Cd
NH and the free oxime group CdNOH from the HNd
CEtON(H)CMe2C(R)dNOH ligand; these data match well
with those for similar complexes derived from the addition
of “simple” oximes, e.g., [PtCln{NHdC(Me)ONdCR1-
Complexes 5-8 display a single broad 195Pt resonance
signal, typical for a PtIICl2N2 or PtIVCl4N2 coordination
environment, with half-height line widths between 700 and
800 Hz, suggesting that only one type of imino complex was
formed in the reactions. The chemical shifts for the platinum-
(II) complexes were found at -2027 and -2031 ppm for 5
and 6, respectively, whereas for platinum(IV) complexes,
the change in the oxidation state of the metal center is
reflected by a significant downfield shift of about 2000 ppm
(-153 and -92 ppm for 7 and 8, respectively), and these
values correspond well to those for related species, i.e.,
[PtCln{NHdC(Me)ONdCR1R2}2] (n ) 2, -2060 ( 30
ppm;36 n ) 4, -120 ( 40 ppm15,18), [PtCln{NHdC(Me)-
ONR3 }2] (n ) 2, -2035 ( 15 ppm;36 n ) 4, -160 ( 10
2
R2 }2],15,17,18,20 or dialkyl- and dibenzylhydroxylamines, e.g.,
ppm13), and [PtCln{NHdC(Et)OR4}2] (n ) 2, -1935 ( 30
ppm;10,37 n ) 4, -100 ( 70 ppm10,37).
2
[PtCln{NHdC(Et)ONR3 }2],14 to Pt-bound nitriles.
2
The addition of the 1,2-hydroxylaminooximes 1 and 2 to
the nitrile platinum(II) and -(IV) complexes trans-[PtCl2-
(EtCN)2] and trans-[PtCl4(EtCN)2], respectively, was moni-
The 1H NMR spectra of the PtII complexes 5 and 6 display
a broad peak in the range of δ 8.10-8.20 ppm assigned to
the imine proton Pt-NH, involved in intramolecular hydro-
gen bonding (observed also in the solid-state molecular
1
tored by H, 13C, 15N, and 195Pt NMR spectroscopy, and
selected data are presented in Table 1. The oxidation state
(36) Wagner, G.; Pakhomova, T. B.; Bokach, N. A.; Frau´sto da Silva, J. J.
R.; Vicente, J.; Pombeiro, A. J. L.; Kukushkin, V. Yu. Inorg. Chem.
2001, 40, 1683.
(37) Cini, R.; Caputo, P. A.; Intini, F. P.; Natile, G. Inorg. Chem. 1995,
34, 1130.
(34) Luzyanin, K. V.; Haukka, M.; Bokach, N. A.; Kuznetsov, M. L.;
Kukushkin, V. Yu.; Pombeiro, A. J. L. Dalton Trans. 2002, 1882.
(35) Kukushkin, V. Yu.; Oskarsson, A° .; Elding, L. I. Inorg. Synth. 1997,
31, 279.
Inorganic Chemistry, Vol. 45, No. 5, 2006 2299

Luzyanin et al.
1
Figure 2. Downfield H,13C HMBC NMR spectrum of 5 in DMSO-d6.
structures; see later), whereas for the PtIV complexes 7 and
8, a downfield shift of about 1 ppm of the corresponding
signal was detected [δ 9.05-9.15 ppm]. These observations
are in a good agreement with NMR spectroscopic data for
similar platinum imino complexes, viz., [PtCln{NHdC(Et)-
ONR3 }2] (n ) 2, 4; R3 ) Me, Et, CH2Ph, CH2C6H4Cl-p).14
2
In the 1H,15N HMQC experiment, two resonances from 15
N
with protons directly bound to a N atom were found. The
signal at 83-95 ppm was assigned to the imine Pt-NH
nitrogen signal, whereas the other (143-151 ppm) corre-
sponds to the NH signal from the hydroxylamine moiety.
Addition of the 1,2-hydroxylaminooximes 1 and 2 to a
coordinated nitrile is accompanied by a change of the 13C
chemical shift of the quaternary carbon atom from the nitrile
to the imino group (CtN to CdN). The CdNH imine 13C
signals were found to resonate in the δ range of 175-180
ppm and are shifted by approximately 60 ppm to lower field
in comparison to the starting platinum nitrile complexes (i.e.,
119 ppm for CtN from trans-[PtCl4(EtCN)2]34).
Figure 3. Thermal ellipsoid view of complex 6 with atomic numbering
scheme. Thermal ellipsoids are drawn at 50% probability.
proceeds via the hydroxylamine group. Furthermore, coup-
ling from this proton to the dimethyl-substituted carbon atom
at 62.4 ppm was observed (not shown). The C(CH3)2 protons,
as well as the ortho protons of the phenyl group (Me in case
of 6 and 8), the O-NH proton, and the oxime (NOH) proton
The 1H and 13C signal assignments were performed
unequivocally by interpretation of gradient-enhanced two-
dimensional 1H,13C HMQC and 1H,13C HMBC NMR spectra.
Especially the long-range shift correlation experiments via
3
display a correlation (via JH,C coupling) to the HO-NdC
quaternary atom, which resonates at 159.9 ppm. These NMR
spectroscopic features were also found in complexes 6-8,
3
1
2JH,C and JH,C coupling were found to be of high value,
consequently leading to a full assignment of H and 13C
because they allowed the detection of the quaternary carbon
atoms and the determination of whether the hydroxylamine
or the oxime functionality was added to the coordinated
nitrile.
chemical shifts and confirming that the nucleophilic addition
to nitriles, ligated to the Pt centers, proceeds exclusively via
the hydroxylamine moiety of the 1,2-hydroxylaminooxime
species 1 and 2.
The structures of 6-8 were determined by single-crystal
X-ray diffraction analysis (Figures 3-5, Tables 2 and 3),
and it was established that (i) in 6-8, the existence of the
pendant oxime group CdN-OH was detected, and this
observation, in addition to the NMR spectroscopic data in
solution (see above), indicates that the 1,2-hydroxylami-
Thus, for example, in the H,13C HMBC NMR spectrum
1
of 5 (Figure 2), the 13C signal of the coordinated imine carbon
atom was detected at 175.6 ppm and assigned through the
shift correlation peaks with both the CH3 and the CH2 protons
from the ethyl residue. A further cross-peak of CdN with
the O-NH proton clearly confirms that the addition reaction
2300 Inorganic Chemistry, Vol. 45, No. 5, 2006

Addition of Hydroxylaminooximes to Pt-Ligated Nitriles
Table 2. Crystallographic Data for 6, 7, 8‚(C7H8), and 9
6
7
8‚(C7H8)
9
empirical
formula
Fw
temp (K)
λ (Å)
cryst syst
Space
group
C
16H34Cl2-
C26H38Cl4N6- C23H42Cl4N6- C5H10Cl2N2-
N6O4Pt
O4Pt
835.51
120(2)
O4Pt
803.52
120(2)
0.71073
triclinic
P1h
O2Pt
396.14
120(2)
0.71073
triclinic
P1h
640.48
120(2)
0.71073
monoclinic monoclinic
P21/n
0.71073
P21/c
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
7.6006(2)
15.4326(6)
10.1530(3)
90
99.141(2)
90
9.8206(6)
15.7599(10)
10.5418(10)
90
97.395(7)
90
7.2923(2)
9.0813(4)
13.2633(6)
77.931(2)
85.591(3)
73.284(3)
822.50(6)
1
8.9309(3)
9.0528(3)
13.2321(6)
99.276(2)
106.497(2)
100.964(2)
980.38(6)
4
1175.79(7)
2
1618.0(2)
2
rcalc
1.809
1.715
1.622
2.684
(Mg/m3)
µ(Mo Ka)
6.227
4.707
4.626
14.820
(mm-1
)
Rint
R1a
(I g 2s)
wR2b
(I g 2s)
0.0389
0.0272
0.0427
0.0241
0.0456
0.0305
0.0730
0.0481
Figure 4. Thermal ellipsoid view of complex 7 with atomic numbering
scheme. Thermal ellipsoids are drawn at 50% probability.
0.0685
0.0397
0.0725
0.1090
2 2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(Fo2 - Fc2)2]/∑[w(Fo ) ]}1/2
.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for 6, 7,
8‚(C7H8), and 9
6
7
8‚(C7H8)
9A
9B
Pt1-Cl1
Pt1-Cl2
Pt1-N1
Pt1-N2
N1-C1
N1-O1
N2-O2
C1-O1
O1-N2
N2-C4
C7-N3
N3-O2
Cl1-Pt1-Cl2
2.3008(7) 2.3042(7)
2.3087(9)
2.3203(8) 2.287(3)
2.3186(8) 2.288(3)
2.301(3)
2.290(3)
2.013(3)
2.013(3)
2.014(3)
1.927(10) 1.916(11)
2.009(10) 1.989(9)
1.568(14) 1.541(16)
1.186(13) 1.206(15)
1.382(13) 1.371(13)
1.265(4)
1.265(4)
1.274(5)
1.351(4)
1.465(3)
1.496(4)
1.281(4)
1.426(3)
1.348(4)
1.444(3)
1.476(4)
1.264(4)
1.406(4)
1.349(4)
1.467(4)
1.478(5)
1.279(5)
1.411(5)
91.11(3)
85.18(9)
112.0(3)
112.9(3)
1.271(15) 1.292(15)
90.62(11) 92.47(12)
Cl1-Pt1-N1 90.74(7)
85.18(8)
113.5(2)
111.1(3)
172.7(3)
80.8(4)
172.3(3)
80.7(4)
C1-O1-N2
C7-N3-O2
N1-Pt1-N2
O1-N1-C1
O2-N2-C4
113.1(2)
110.6(2)
116.0(10) 115.8(11)
118.2(10) 116.9(9)
Figure 5. Thermal ellipsoid view of complex 8‚(C7H8) with atomic
numbering scheme. Thermal ellipsoids are drawn at 50% probability. The
toluene molecule has been omitted for clarity.
significantly affect the reactivity. To investigate whether the
kinetic and thermodynamic characteristics of these processes
are coherent or opposite, quantum chemical calculations of
the possible products of the reactions of free acetonitrile
MeCN and the four ligated nitriles trans-[PtCln(NCMe)2] [n
) 2 (T1), 4 (T2)] and [PtClm(NCMe)]- [m ) 3 (T3), 5 (T4)]
with the model bifunctional nucleophile HONdCHCH2-
NHOH were performed at the B3LYP level of theory.
An inspection of the energies of the calculated structures
NHdC(Me)ON(H)CH2CHdNOH (H5), trans-[PtCln{NHd
C(Me)ON(H)CH2CHdNOH}2] [n ) 2 (H6), 4 (H7)],
[PtClm{NHdC(Me)ON(H)CH2CHdNOH}]- [m ) 3 (H8),
5 (H9)], NHdC(Me)ONdCHCH2N(H)OH (O5), trans-
[PtCln{NHdC(Me)ONdCHCH2N(H)OH}2] [n ) 2 (O6), 4
(O7)], and [PtClm{NHdC(Me)ONdCHCH2N(H)OH}]- [m
) 3 (O8), 5 (O9)] leads to the following conclusions (see
Supporting Information for the table with the absolute
energies). First, the products of the addition by the hydroxyl-
amine site (H5-H9) are more stable than the corresponding
nooximes react with PtII- and PtIV-bound nitriles exclusively
via the hydroxylamine moiety; (ii) all of the imino ligands
are mutually trans and are in the E configuration; and (iii)
all bond lengths and angles are not unusual and are within
the expected limits.38
Theoretical Studies of Thermodynamic Aspects of the
Regioselectivity of the Coupling. The results of both
synthetic and kinetic work (see later) clearly demonstrate
that the high regioselectivity of the nucleophilic addition of
the bifunctional hydroxylaminooximes to the complexed
nitriles should be explained by kinetic reasons. However,
there is another factor, i.e., thermodynamics, that might
(38) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1. Allen, F. H.;
Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A. G.; Taylor, R.
J. Chem. Soc., Perkin Trans. 2 1987, S1.
Inorganic Chemistry, Vol. 45, No. 5, 2006 2301

Luzyanin et al.
Scheme 3
Table 4. Reaction Energies (in kcal/mol) for the Formation of the
Products H/O5-H/O9 upon Addition of HON(H)CH2C(H)dNOH to
Nitrilesa
∆Ε
∆Η
∆G
5H
6H
7H
8H
9H
5O
6O
7O
8O
9O
-14.69 (-13.21)
-54.98 (-49.04)
-67.62 (-62.72)
-23.85 (-21.24)
-30.62 (-29.12)
-12.97 (-11.35)
-48.78 (-42.53)
-61.81 (-56.03)
-19.90 (-18.05)
-27.19 (-25.05)
-12.50
-49.75
-63.03
-21.39
-28.16
-10.95
-44.03
-56.38
-17.63
-24.89
-0.21 (+1.26)
-20.86 (-14.92)
-33.11 (-28.22)
-6.76 (-4.15)
-13.63 (-12.13)
+1.08 (+2.70)
-16.74 (-10.49)
-29.58 (-23.80)
-4.30 (-2.45)
-10.35 (-8.21)
species.14 These reactions can be considered as standards in
investigations of the reactivity of other incoming nucleo-
philes.
Here, we report kinetic data for the addition of 1,3-
diphenylpropan-2-one oxime, HONdC(CH2Ph)2, to the PtIV
complex [Ph3PCH2Ph][PtCl5(EtCN)] (11) to give [Ph3PCH2-
Ph][PtCl5{NHdC(Et)ONdC(CH2Ph)2}] (12; for its charac-
terization, see the Experimental Section) in order to compare
rate constants with those for the addition of the relevant
hydroxylamines HONR2 (R ) CH2Ph and CH2C6H4Cl-p)14
and, subsequently, to verify kinetic aspects and trends in the
addition of both types of nucleophiles to coordinated nitriles.
Complex 11 was chosen for this study because the PtIV center
provides a substantial electrophilic activation of the nitrile
toward even very weak nucleophiles19 and, in addition, the
coupling between oximes and PtII complexes does not
proceed at all.14
Initially, some structural features of the O-nucleophiles
hydroxylamines and oximes appear similar, but in fact, the
NdC double bond in oximes could noticeably reduce their
nucleophilic reactivity by making the nucleophilic center
electron-poorer. Note that these nucleophilic addition reac-
tions proceed in dichloromethane or chloroform as the
solvent, and therefore, neutral uncharged forms of both
hydroxylamines and oximes should be considered as reactive
species.
a Energies corrected for the solvent effect are in parentheses.
oxime addition complexes (O5-O9), by 1.44, 4.43, 4.42,
1.70, and 3.92 kcal/mol, respectively, in terms of Gibbs free
energy in solution (∆Gs), although, in some cases, this
difference is small. Hence, there is a direct correlation
between the kinetically and thermodynamically preferred
products of the reactions. Second, all of the reactions are
exothermic and exoergonic, except the addition to free MeCN
(Table 4). The ∆G magnitudes are significantly lower, in
absolute values, than ∆H because of a strong decrease of
the entropy upon addition. The endoergonic character of the
reactions with free MeCN accounts for the experimentally
observed spontaneous splitting of the imino species, e.g.,
HNdC(Et)ONdC(Me)C(Me)(dO),21 to the parent nitrile and
dione monoxime, whereas the corresponding platinum spe-
cies trans-[PtCl2{NHdC(Et)ONdC(Me)C(Me)(dO)}2] are
stable.21 Third, the coordination of MeCN by platinum results
in significant increases of |∆H| and |∆G|. The change of
the oxidation state of the metal center has a markedly greater
effect on the reaction energies (by 6-8 kcal/mol per ligand)
than the variation of the overall charge of the complex moiety
(by 2-4 kcal/mol per ligand). Thus, the exothermic and
exoergonic character of the reactions increases along the
sequence MeCN , T3 (PtII, anionic complex) < T1 (PtII,
neutral complex) < T4 (PtIV, anionic complex) < T2 (PtIV,
neutral complex). This trend perfectly correlates with both
kinetic data (ref 14 and this work) and qualitative synthetic
results that show the enhancement of the reactivity according
to the same trend. Fourth, consideration of the effects of the
solvent leads to a decrease of the reaction energies (in
absolute values) in comparison to gas-phase calculations
because of the higher stabilization, in solution, of the
reactant’s level than the product’s level.
Kinetics of Nucleophilic Addition of 1,3-Diphenylpro-
pan-2-one Oxime to PtIV-Bound Propiononitrile. Despite
significant achievements in synthetic approaches to metal-
mediated additions to RCN ligands, the existing knowledge
about actual reactiVity of incoming nucleophiles is rather
rudimentary. Therefore, we recently launched systematic
kinetic and mechanistic studies of nucleophilic additions to
nitriles at PtII and PtIV centers. In particular, we have
demonstrated that the nucleophilic addition of dibenzylhy-
droxylamines HONR2 (R ) CH2Ph and CH2C6H4Cl-p) to
NtCEt coordinated to PtII and PtIV follows clean second-
order kinetics and the reactivity of PtIV complexes is 103
times higher than the reactivity of the corresponding PtII
The kinetics of the reaction depicted in Scheme 3 was
1
studied by H NMR spectroscopy under conditions very
similar to those used for the reaction with HON(CH2Ph)2
and HON(CH2C6H4Cl-p)2.14 The majority of runs were
performed at 50 °C, where the reaction is complete within
0.5-1 h. In the presence of 8-80-fold excesses of the oxime,
a satisfactory pseudo-first-order behavior was observed for
complex 11. The values of pseudo-first-order rate constants
kobs showed no variation for at least 3-5 half-lives. The
dependence of kobs on oxime concentration is linear without
any significant intercept (Figure 6). Therefore, kobs
)
k2[oxime], implying that the kinetic features of the additions
of hydroxylamines and oximes match nicely.
The second-order rate constants k2 were obtained at 40,
50, 55, and 60 °C (Table 5) and used for calculating the
corresponding activation parameters ∆Hq and ∆Sq, which
are included in Table 6. The rate constants k2 are unaffected
by excess free propiononitrile. The same values of k2 were
obtained in the presence of a 100-fold excess of EtCN
relative to 11. Furthermore, free propiononitrile does not react
with the oxime in chloroform for 1 week at 45 °C.
The results obtained in this and previous14 works clearly
indicate that the reactivity of hydroxylamines is significantly
higher than that of oximes. The activation parameters in
Table 6 allow for the calculation of the rate constant k2 as
2302 Inorganic Chemistry, Vol. 45, No. 5, 2006

Addition of Hydroxylaminooximes to Pt-Ligated Nitriles
Figure 7. Thermal ellipsoid view of complex 9 with atomic numbering
scheme. Thermal ellipsoids are drawn at 50% probability. The asymmetric
unit contained two independent molecules. The second molecule has been
omitted for clarity.
Figure 6. Pseudo-first-order rate constants kobs as a function of oxime
concentration for reaction depicted in Scheme 3: 50 °C, CDCl3 solvent,
[11] ) 1.35 × 10-3 M.
crystals of 9 and 10 along with the starting materials and
yet unidentified noncrystalline decomposition species. Au-
thentic crystals of 9 were also obtained by vapor diffusion
of diethyl ether into a DMF solution of 6 for 1 week at room
temperature. X-ray determinations show that decomposition
of 6 (route G) leads to, in particular, the unusual nitrosoal-
kane complex [PtCl2{HONdC(Me)C(Me)2NdO}] (9),
whereas in the case of 5 (route H), we succeeded in isolating
and identifying the metal-free species [H3NC(Me)2C(Ph)d
NOH]2(NO3)Cl‚H2O (10) (for the X-ray structure of this salt,
see the Supporting Information), which possibly originates
from the disproportionation of the hydroxylamine functional-
Table 5. Rate Constants for the Reaction Depicted in Scheme 3 (in
CDCl3)
T (°C)
[oxime] (M)
k
obs (s-1
)
k2 (M-1 s-1
)
40.0
2.69 × 10-2
1.08 × 10-2
1.35 × 10-2
2.69 × 10-2
5.38 × 10-2
1.08 × 10-1
2.69 × 10-2
2.69 × 10-2
(2.3 ( 0.4) × 10-4
(2.1 ( 0.2) × 10-4
(3.2 ( 0.8) × 10-4
(4.8 ( 0.2) × 10-4
(9.3 ( 0.4) × 10-4
(1.9 ( 0.1) × 10-3
(8.6 ( 0.4) × 10-4
(1.6 ( 0.3) × 10-3
(8.8 ( 0.5) × 10-3
(1.8 ( 0.1) × 10-2
50.0
55.0
60.0
(3.3 ( 0.2) × 10-2
(6.3 ( 0.3) × 10-2
-
ity41 to afford the amine group and NO3 ; compound 10 is
Table 6. Activation Parameters for Reactions of 11 with Different
Nucleophiles in CDCl3
known from the literature.42
In the IR spectrum of 9, there are two strong bands at
1658 cm-1 assigned to ν(CdN) of the oxime group CdNOH
and at 1547 cm-1 due to ν(NdO) from the nitroso group of
the newly formed ligand. In the X-ray structure of 9 (see
Figure 7), the ligand HONdC(Me)C(Me)2NdO is coordi-
nated to the Pt(II) center by both the oxime and nitroso
nitrogens, forming a five-membered chelate ring similar to
that observed in related platinum chelates of the type [PtCl2-
(NN)].43 The measured NdO bond distance from the nitroso
fragment is 1.206(15) Å, and this value agrees well with
that for the relevant platinum nitrosoalkane complexes, i.e.,
trans-[PtCl2{Me3C(NdO)}2] [1.21(1) Å]44 and [PtCl2{N(d
O)CR2ONCR2}] (R ) Me, C5H10) (1.21-1.24 Å).43
incoming nucleophile ∆Hq (kJ mol-1
)
∆Sq (J mol-1 K-1
)
ref
HON(CH2C6H4Cl-p)2
HONdC(CH2Ph)2
56 ( 6
81 ( 10
-47 ( 23
-27 ( 31
14
this work
3.9 × 10-6 M-1 s-1 at -20 °C. Measured at this temperature,
the rate constant for HON(CH2C6H4Cl-p)2 equals 6.5 × 10-2
M-1 s-1.14 Hence, the hydroxylamine is a factor of 1.7 ×
104 more reactive than the oxime. Inspection of Table 6
suggests that the significantly lower enthalpy of activation,
∆Hq, accounts for this difference. The entropies of activation,
∆Sq, are negative, similar, and typical of clean second-order
reactions.39,40
There is no doubt that the HO-nucleophilicity of hydroxyl-
amines is substantially higher than that of oximes. It is very
likely that the lone-pair electrons of oxygen are significantly
delocalized over the O-NdC moiety of the oxime. As a
result, the highest occupied molecular orbital (HOMO) of
oximes is lower in its energy than that of hydroxylamines
(by 0.38 eV for HONdCMe2 and HONMe2 at the B3LYP/
6-31G* level of theory), providing the slower nucleophilic
attack for the former reagent.
(41) Alluisetti, G. E.; Almaraz, A. E.; Amorebieta, V. T.; Doctorovich, F.;
Olabe, J. A. J. Am. Chem. Soc. 2004, 126, 13432. Kuznetsova, N. I.;
Kuznetsova, L. I.; Detusheva, L. G.; Likholobov, V. A.; Pez, G. P.;
Cheng, H. J. Mol. Cat. A: Chem. 2000, 161, 1. Hieber, W.; Nast, R.;
Proeschel, E. Z. Anorg. Chem. 1948, 256, 159; Chem. Abstr. 1949,
43, 17093. Banyai, I.; Gyemant, G.; Dozsa, L.; Beck, M. Magyar
Kemiai Folyoirat 1988, 94, 420; Chem. Abstr. 1989, 110, 102607.
Nast, R.; Foppl, I. Z. Anorg. Allg. Chem. 1950, 263, 310; Chem. Abstr.
1951, 45, 21375.
(42) Volodarskii, L. B.; Tormysheva, N. Yu. IzV. Sib. Otd. Akad. Nauk
SSSR, Ser. Khim. 1976, 136; Chem. Abstr. 1976, 85, 159592. Gnichtel,
H.; Schuster, K. E. Chem. Ber. 1978, 3, 1171; Chem. Abstr. 1978, 88,
190684. Martin, V. V.; Volodarskii, L. B. Khim. Geterotsiklicheskikh
Soed. 1979, 103; Chem. Abstr. 1979, 90, 186860. Gnichtel, H.; Belkien,
L.; Totz, W.; Wawretschek, L. Liebigs Ann. Chem. 1980, 7, 1016;
Chem. Abstr. 1980, 93, 186245. Titova, T. F.; Krysin, A. P.; Martin,
V. V. Khim. Geterotsiklicheskikh Soed. 1986, 62; Chem. Abstr. 1986,
106, 67184. Hanss, J.; Beckmann, A.; Krueger, H.-J. Eur. J. Inorg.
Chem. 1999, 1, 163; Chem. Abstr. 1999, 130, 162340.
Further Conversions of 5 and 6. When the syntheses of
5 and 6 (Scheme 2) were performed in air under prolonged
heating (45 °C, 12 h) followed by slow evaporation of the
solution for 1 day, the reactions resulted in the formation of
(39) Espenson, J. H. Chemical Kinetics and Reaction Mechanisms, 2nd
ed.; McGraw-Hill: New York, 1995.
(40) Wilkins, R. G. Kinetics and Mechanism of Reactions of Transition
Metal Complexes, 2nd ed.; VCH: Weinheim, Germany, 1991.
(43) Kukushkin, V. Yu.; Belsky, V. K.; Aleksandrova, E. A.; Konovalov,
V. E.; Kirakosyan, G. A. Inorg. Chem. 1992, 31, 3836. Kukushkin,
V. Yu.; Tudela, D.; Izotova, Y. A.; Belsky, V. K.; Stash, A. I. Inorg.
Chem. 1996, 35, 4926.
Inorganic Chemistry, Vol. 45, No. 5, 2006 2303

Luzyanin et al.
It is worth mentioning that, even though oxidations of 1,2-
hydroxylaminooxime species involving metal centers to
afford nitrosoalkane complexes are known,45-47 the formation
of a (nitrosoalkane)platinum(II) complex by route G (Scheme
2) is the first example of this kind in platinum chemistry.
Moreover, (nitrosoalkane)platinum(II) complexes are so far
quite rare, and the known examples include only trans-[PtCl2-
{Me3C(NdO)}2]44 and [PtCl2{N(dO)CR2ONCR2}] (R )
Me, C5H10).43 It is anticipated that the reaction of 1,2-
hydroxylaminooximes with PtII precursors, in air, might
constitute an entry to these complexes, and this project is
underway in our group.
promoters, of such HON-nucleophiles as oximes23 (routes
A and B) or N,N-substituted hydroxylamines23,49 (route C).
In fact, the cyclotetramerization of o-phthalonitriles I to yield
phthalocyanines II requires a two-electron reduction and the
donation of two protons from a promoter.7 From this
perspective, it is clear that substantially higher tetramerization
rates in the case of hydroxylamines than in the case of oximes
can be explained by both better nucleophilic properties
toward the nitrile group (this work) and higher reducing
abilities (ref 50) of the former compared to the latter.
Experimental Section
Final Remarks. In synthetic experiments, it has been
demonstrated that the 1,2-hydroxylaminooximes, i.e., re-
agents bearing both hydroxylamine and oxime HO moieties,
react readily with both PtII- and PtIV-ligated EtCN to achieve,
with a high degree of regioselectivity, the product of
hydroxylamine-site addition to the nitrile group. This reaction
represents an unusual reactivity pattern for 1,2-hydroxylami-
nooximes, which were previously employed mostly as
sequestering reagents48 for various metal centers.
In complete accord with the synthetic work, the kinetic
study revealed that N,N-disubstituted hydroxylamines, as
compared to the structurally related oxime species, are ca.
104-fold better nucleophiles toward PtIV-bound EtCN. More-
over, the computational study explicitly shows that the
platinum-mediated nitrile-hydroxylamine coupling gives
products that are more thermodynamically stable than those
derived from the nitrile-oxime coupling. The verified kinetic
and thermodynamic aspects of the metal-mediated nitrile-
hydroxylamine and nitrile-oxime coupling make highly
unfavorable the mechanism involving the addition of 1,2-
hydroxylaminooximes to RCN ligands via the oxime site
followed by isomerization of [M]-N(H)dC(R)ONdC-CN-
(H)OH species to achieve the appropriate [M]-N(H)dC(R)-
ON(H)C-CdNOH-type complexes.
Materials and Instrumentation. The preparations of the nitrile
platinum(II) and platinum(IV) complexes trans-[PtCln(EtCN)2] (n
) 2, 3;35,51 n ) 4, 434) and [Ph3PCH2Ph][PtCl5(EtCN)] (11)19 were
reported previously. 1,2-Hydroxylaminooximes 1 and 2‚MeCO2H
and HONdC(CH2Ph)2 (1,3-diphenylpropan-2-one oxime) were
synthesized in accord with the published procedures.52 Solvents
were obtained from commercial sources and used as received. C,
H, and N elemental analyses were carried out by the Microanalytical
Service of the Instituto Superior Te´cnico. For thin-layer chroma-
tography (TLC), Merck UV 254 SiO2 plates were used. FAB+ and
FAB- mass spectra were obtained on a Trio 2000 instrument by
bombarding 3-nitrobenzyl alcohol (NBA) matrixes of the samples
with 8 keV (ca. 1.28 × 1015 J) Xe atoms. Mass calibration for data
system acquisition was achieved using CsI. Infrared spectra (4000-
400 cm-1) were recorded on a JASCO FTS 3000MX instrument
in KBr pellets. 1D NMR experiments, i.e., 1H, 13C{1H}, and 195Pt,
and 2D NMR correlation experiments, i.e., 1H,13C HMQC, 1H,13C
1
HMBC, and H,15N HMQC, were performed on Bruker Avance
DPX 400 (UltraShield Magnet) and Varian UNITY 300 spectrom-
eters at ambient temperature. 195Pt NMR chemical shifts are given
relative to K2[PtCl6] (0.0 ppm), and 15N NMR chemical shifts are
relative to NH4Cl (0.0 ppm).
X-ray Structure Determinations. X-ray diffraction data were
collected with a Nonius KappaCCD diffractometer using Mo KR
radiation (λ ) 0.71073 Å). Crystals were mounted in inert oil within
a cold gas stream of the diffractometer. The Denzo-Scalepack53
[6, 8‚(C7H8), 9, 10] or EvalCCD54 (7) program packages were used
for cell refinements and data reduction. Structures were solved by
All the more important is that the obtained results shed
light on the mechanism and driving forces of the recently
discovered mild protocol for syntheses of metal-containing
and metal-free phthalocyanines from o-phthalonitriles;23,24
the basic reaction (Scheme 1) involves application, as
direct methods using the SHELXS-97 or SIR97 programs.55,56
A
multiscan absorption correction based on equivalent reflections
(49) Luzyanin, K. V.; Kukushkin, V. Yu.; Kopylovich, M. N.; Pombeiro,
A. J. L. Unpublished results, 2006.
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J. S.; McGrorty, S. M.; Ulloa, E. M. Can. J. Chem. 2003, 81, 575 and
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Chem. Scand. 1995, 49, 72. Kukushkin, V. Yu.; Oskarsson, A° .; Elding,
L. I. Zh. Obsch. Khim. 1994, 64, 881; Russ. J. Gen. Chem. (Engl.
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2, 114; Chem. Abstr. 1966, 64, 14139h; Putsykin, Yu. G.; Volodarskii,
L. B. IzV. Sib. Otd. Akad. Nauk SSSR, Ser. Khim. Nauk 1968, 4, 101;
Chem. Abstr. 1969, 70, 46764a. Dayagi, S.; Degani, Y. In The
Chemistry of the Carbon-Nitrogen Double Bond; Patai, S., Ed.;
Interscience: London, 1970; p 111.
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Collected in Oscillation Mode. In Methods in Enzymology, Macro-
molecular Crystallography; Carter, C. W., Jr., Sweet, R. M., Eds.;
Academic Press: New York, 1997; Part A, Vol. 276, pp 307-326.
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SSSR, Ser. Khim. 1986, 2110; Chem. Abstr. 1987, 107, 58574.
Larionov, S. V.; Kosareva, L. A.; Boguslavskii, E. G. IzV. Akad. Nauk
SSSR, Ser. Khim. 1984, 2592; Chem. Abstr. 1985, 102, 55084.
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Koord. Khim. 1985, 11, 254; Chem. Abstr. 1985, 103, 29395.
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B. Zh. Obshch. Khim. 1986, 56, 684; Chem. Abstr. 1986, 105, 202125.
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SSSR, Ser. Khim. 1991, 9, 1959. Chem. Abstr. 1992, 116, 142636.
Troepol’skaya, T. V.; Vagina, G. A.; Morozov, V. I.; Kitaev, Yu. P.
IzV. Akad. Nauk SSSR, Ser. Khim. 1988, 6, 1268; Chem. Abstr. 1988,
109, 118041. Larionov, S. V.; Kosareva, L. A.; Boguslavskii, E. G.
IzV. Akad. Nauk SSSR, Ser. Khim. 1986, 9, 2110; Chem. Abstr. 1987,
107, 58574. Larionov, S. V.; Kosareva, L. A. Zh. Neorg. Khim. 1986,
31, 2334; Chem. Abstr. 1986, 105, 182829. D’yachenko, S. A.;
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University of Go¨ttingen, Go¨ttingen, Germany, 1997.
2304 Inorganic Chemistry, Vol. 45, No. 5, 2006

Addition of Hydroxylaminooximes to Pt-Ligated Nitriles
{XPREP in SHELXTL57 version 6.14-1 [6, 8‚(C7H8), 10] or
SADABS version 2.10 (7)}58 or analytical absorption correction
(de Meullenaer and Tompa)59 was applied to data [Tmin/Tmax values
were 0.2539/0.6103, 0.4381/0.7622, 0.2982/0.7259, 0.2470/0.6327,
and 0.9572/0.9855 for 6, 7, 8‚(C7H8), 9, and 10, respectively]. The
structures were refined with SHELXL-9760 and the WinGX
graphical user interface.61 Structure 9 contained two independent
molecules in the asymmetric unit. In 6, 9, and 10, the OH, H2O,
and NH hydrogens were located from difference Fourier maps but
not refined. The methyl groups of the toluene solvent in 8‚(C7H8)
were disordered over two sites with equal occupancies of 0.5. In
7, the OH hydrogen was located from the difference Fourier map
and refined isotropically. In 8‚(C7H8), OH and NH hydrogens were
located from the difference Fourier map and modeled with isotropic
displacement parameters and distance constraints (0.85 Å). Other
hydrogens were placed in idealized positions and constrained to
ride on their parent atoms. The crystallographic details for 6-9
are summarized in Table 2, and selected bond lengths and angles
are reported in Table 3. The crystallographic details of 10 are given
as Supporting Information.
results obtained at the B3LYP level agree well with those calculated
using higher correlated methods.
The Hessian matrix was calculated analytically for all optimized
structures to verify the location of correct minima (no “imaginary”
frequencies) and to estimate the zero-point-energy (ZPE) correction
and thermodynamic parameters; the latter were calculated at 25
°C. The reaction energies (∆E) and reaction enthalpies and Gibbs
free energies (∆H and ∆G) were calculated as the differences in
energy of the product and sum of the energies of the reactants.
Solvent effects were taken into account at the single-point calcula-
tions based on the gas-phase equilibrium geometries by using the
polarizable continuum model69 in the CPCM version70 with CHCl3
as a solvent. The Gibbs free energies in solution (Gs) were estimated
by addition of the ZPE, thermal, and entropic contributions taken
from the gas-phase calculations (δGg) to the single-point CPCM-
SCF energy (Es).
The experimental X-ray structures of trans-[PtCln{NHdC(Et)-
ONHCMe2C(Me)dNOH}2] (n ) 2, 4) (current work), [Ph3PCH2-
Ph][PtCl5{NHdC(Et)ON(CH2Ph)2}],14 [Ph3PCH2Ph][PtCl5{NHd
C(Et)ONdC(C9H16)}],19 trans-[PtCl2{NHdC(Me)ONdCMe2}2],36
and trans-[PtCl4{NHdC(Me)ONdC(Me)C(Me)dNOH}2]17 were
chosen as the starting geometries for the optimization. The
equilibrium geometries and the main calculated bond lengths of
H/O5-H/O9 are in reasonable agreement with the experimental
data. The maximum deviations of the theoretical and experimental
parameters are 0.1 and 0.05 Å for the Pt-Cl and Pt-N bonds,
respectively, whereas the difference for the other bonds does not
exceed 0.03 Å, often falling within the 3σ interval of the X-ray
data.
Kinetic Measurements. The kinetics of the reaction depicted
in Scheme 3 was studied in CDCl3 using a Varian UNITY 300
NMR spectrometer equipped with an indirect detection probe and
a thermostated module in the temperature range from 40 to 60 °C.
The progress of the reactions was monitored by integrating the 1H
NMR signals from the coordinated EtCN of 11 or signals of the Et
group from the imino ligand of [Ph3PCH2Ph][PtCl5{NHdC(Et)-
ONdC(CH2Ph)2}] (for its complete characterization, see later). The
pseudo-first-order conditions were ensured by using at least an
8-fold excess of HONdC(CH2Ph)2 (DBO) with respect to 11. The
reactions were initiated by mixing solutions of 11 and DBO in
CDCl3 to give the total solution volume of 0.5 mL. Commonly
used concentrations of 11 and DBO were 1.35 × 10-3 and (1.08-
10.8) × 10-2 M, respectively. The pseudo-first-order rate constants
kobs were calculated from the slope of linear plots of ln[100/(100
- x)] versus time where x (in percent) is the conversion of the
starting material to the product of the reaction. All kobs rate constants
throughout are the mean values of at least three measurements. The
curve fit and all other calculations were performed using the Origin
6.1 package.
Synthetic Work. Addition of HON(H)CMe2C(R)dNOH to
[PtCln(EtCN)2]. In a typical experiment, 3 or 4 (0.1 mmol) was
dissolved in chloroform (5 mL) at 20-25 °C, the corresponding
1,2-hydroxylaminooxime 1 or 2‚MeCO2H (0.2 mmol) was added,
and the reaction mixture was heated at 40 °C for ca. 15 min. In the
cases of 5 and 7, the bright yellow solution was evaporated to
dryness at room temperature under a flow of N2, and the solid
residue was washed with cold chloroform (1 mL) and pentane (five
3-mL portions) to remove the unreacted reagents. In the cases of 6
and 8, the bright yellow precipitate formed was washed with cold
chloroform (1 mL) and ether (five 1-mL portions) to remove the
unreacted reagents. Yields were 80-85%, based on Pt.
Computational Details. The full geometry optimization of all
structures was carried out in Cartesian coordinates using the
Gaussian 9862 program package at the DFT level of theory. The
calculations were performed using Becke’s three-parameter hybrid
exchange functional63 in combination with the gradient-corrected
correlation functional of Lee, Yang, and Parr64 (B3LYP). A
quasirelativistic Stuttgart pseudopotential described 60 core elec-
trons, and the appropriate contracted basis set (8s7p6d)/[6s5p3d]65
for the platinum atom and the 6-31G* basis set for other atoms
were used. The combination of the B3LYP functional and the
mentioned basis set was found to be a quite reasonable approxima-
tion for the investigation of properties of transition metal
complexes,66-68 including platinum species,12,66 taking into account
the low computational cost of this method and the fact that the
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V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;
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Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Baboul, A. G.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts,
R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C.
Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.;
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Inorganic Chemistry, Vol. 45, No. 5, 2006 2305

Luzyanin et al.
trans-[PtCl2{NHdC(Et)ON(H)CMe2C(Ph)dNOH}2] (5). Anal.
Calcd for C26H38N6Cl2O4Pt: C, 40.84; H, 5.01; N, 10.99%.
Found: C, 40.70; H, 4.84; N, 10.87%. FAB+-MS, m/z: 764 [M]+,
692 [M - 2Cl - H]+. IR spectrum (selected bands), cm-1: 3180
mw ν(N-H), 1663 s ν(CdN). 1H NMR spectrum in CDCl3/DMSO-
d6 (9:1), δ: 1.30 (s, 6H, NCMe2), 1.37 (t, J ) 7.2 Hz, 3H, CH2Me),
3.02 (quart, J ) 7.2 Hz, 2H, CH2Me), 6.76 (s, 1H, ONH), 7.16-
7.40 (m, 5H, Ph), 8.18 (s, br, 1H, NH), 9.84 (s, 1H, NOH). 13C-
{1H} NMR spectrum in CDCl3/DMSO-d6 (9:1) (through direct
13C{1H} observation and 1H,13C HMQC, and 1H,13C HMBC
experiments), δ: 10.5 (CH3) and 26.4 (CH2)(Et), 23.5 (NCMe2),
62.4 (NCMe2), 126.3-131.5 (Ph), 159.9 (ONdC), 175.6 (HNd
C). 15N NMR spectrum in CDCl3/DMSO-d6 (9:1) (through 1H,15N
HMQC experiment), δ: 93.1 (HNdC), 143.8 (ONH). 195Pt NMR
spectrum in CDCl3/DMSO-d6 (9:1), δ: -2031 (800 Hz).
crystals of 10 and 9 along with the unreacted starting material and
yet unidentified noncrystalline decomposition species. Authentic
crystals of 9 were also obtained by vapor diffusion of diethyl ether
into a DMF solution of 6 for 1 week at room temperature.
[PtCl2{HONdC(Me)C(Me)2NdO}] (9). Anal. Calcd for
C5H10N2Cl2O2Pt: C, 15.16; H, 2.54; N, 7.07%. Found: C, 15.00;
H, 2.34; N, 6.80%. IR spectrum (selected bands), cm-1: 3238 mw
1
ν(O-H), 1658 s ν(CdN), 1547 s ν(NdO). H NMR spectrum in
DMSO-d6, δ: 1.20 (s, 6H, NCMe2), 1.84 (s, 3H, NdCMe).
Synthesis of [Ph3PCH2Ph][PtCl5{NHdC(Et)ONdC(CH2Ph)2}]
(12) was performed analogously to that described for [Ph3PCH2-
Ph][PtCl5{NHdC(Et)ONdCMe2}].19 The yield was 85%. Anal.
Calcd for C43H42N2Cl5OPPt: C, 51.33; H, 4.21; N, 2.78%. Found:
C, 52.33; H, 4.17; N, 2.60%. FAB--MS, m/z: 581 [M - 2Cl]-,
373 [PtCl5]-. IR spectrum (selected bands), cm-1: 3228 mw ν-
(N-H), 1656 s ν(CdN). 1H NMR spectrum in CDCl3, δ: 1.30 (t,
J ) 7.5 Hz, 3H, CH2Me), 2.33 (quart, J ) 7.2 Hz, 2H, CH2Me),
3.73 (s, 4H, NdCCH2), 5.34 (s, 4H, PCH2Ph), 7.01-7.63 (m, 30H,
Ph) 9.12 (s, 1H, NH). 13C{1H} NMR spectrum in CDCl3 (through
direct 13C{1H} observation), δ: 10.6 (CH3) and 25.3 (CH2)(Et),
trans-[PtCl2{NHdC(Et)ON(H)CMe2C(Me)dNOH}2] (6). Anal.
Calcd for C16H34N6Cl2O4Pt: C, 30.01; H, 5.35; N, 13.12%.
Found: C, 29.42; H, 5.03; N, 12.56%. FAB+-MS, m/z: 604 [M -
Cl - H]+, 569 [M - 2Cl]+. IR spectrum (selected bands), cm-1
:
3189 m-w ν(N-H), 1660 s and 1595 m ν(CdN). 1H NMR
spectrum in DMSO-d6, δ: 1.20 (t, J ) 7.2 Hz, 3H, CH2Me), 1.24
(s, 6H, NCMe2), 1.80 (s, 3H, NdCMe), 2.85 (quart, J ) 7.2 Hz,
2H, CH2Me), 5.70 (s, 1H, ONH), 8.16 (s, br, 1H, NH), 10.68 (s,
1H, NOH). 13C{1H} NMR spectrum in DMSO-d6 (through direct
13C{1H} observation and 1H,13C HMQC, and 1H,13C HMBC
experiments), δ: 10.3 (CH3) and 26.8 (CH2)(Et), 10.2 (NdCMe),
23.2 (NCMe2), 62.4 (NCMe2), 157.9 (ONdC), 177.0 (HNdC). We
were unable to perform the 15N NMR measurements due to
instability of the compound in DMSO-d6. 195Pt NMR spectrum in
DMSO-d6, δ: -2027 (800 Hz).
1
32.6 (CH2, JPC ) 44.0, PCH2Ph), 39.4 (CH2, NCH2Ph2), 126.6-
136.5 (Ph), 168.7 (NdC), 177.0 (HNdC). We were unable to
perform the 15N NMR measurements because of the rather poor
solubility of the compound in CDCl3 and instability in DMSO-d6.
195Pt NMR spectrum in CDCl3, δ: -6 (290 Hz).
Acknowledgment. This work was partially supported by
the Fundac¸a˜o para a Cieˆncia e a Tecnologia (FCT), Portugal,
and its POCTI program (POCTI/QUI/43415/2001 project)
(FEDER funded). K.V.L. and M.L.K. express gratitude to
FCT and the POCTI program (FEDER funded), Portugal,
for fellowships (Grants SFRH/BD/10464/2002 and BPD/
16369/98//BPD/5558/2001). The authors thank NATO for
the Collaborative Linkage Grant PST.CLG.979289. V.Yu.K.
is very much obliged to the Russian Fund for Basic Research
(Grants 06-03-32065 and 05-03-32140), the Scientific Coun-
cil of the President of the Russian Federation (Grant MK-
1040.2005.3), the POCTI program (FEDER funded) (Cien-
tista Convidado/Professor at the Instituto Superior Te´cnico,
Portugal), the Academy of Finland for support of the
cooperation with the University of Joensuu, and ISSEP for
the Soros Professorship. M.L.K. thanks the Russian Fund
for Basic Research for a grant (05-03-32504), M.G. thanks
the Austrian Science Fund (FWF), M.H. thanks the Academy
of Finland, and E.V.T. and V.I.O. thank Bruker for financial
support of their studies. The authors also thank Dr. N.A.
Bokach for experimental assistance and Dr. P.F. Kelly for
valuable suggestions.
trans-[PtCl4{NHdC(Et)ON(H)CMe2C(Ph)dNOH}2] (7). Anal.
Calcd for C26H38N6Cl4O4Pt: C, 37.38; H, 4.58; N, 10.06%.
Found: C, 37.29; H, 4.85; N, 9.61%. FAB+-MS, m/z: 835 [M +
H]+, 765 [M - 2Cl + H]+. IR spectrum (selected bands), cm-1
:
1
3197 s ν(N-H), 1652 vs ν(CdN). H NMR spectrum in CDCl3/
DMSO-d6 (9:1), δ: 1.25 (t, J ) 7.2 Hz, 3H, CH2Me), 1.30 (s, 6H,
NCMe2), 3.42 (quart, J ) 7.2 Hz, 2H, CH2Me), 6.66 (s, 1H, ONH),
7.12-7.40 (m, 5H, Ph), 9.14 (s, br, 1H, NH), 9.39 (s, 1H, NOH).
13C{1H} NMR spectrum in CDCl3/DMSO-d6 (9:1) (through direct
13C{1H} observation and 1H,13C HMQC, and 1H,13C HMBC
experiments), δ: 10.9 (CH3) and 24.7 (CH2)(Et), 23.4 (NCMe2),
62.9 (NCMe2), 127.4-131.0 (Ph), 160.8 (ONdC), 179.5 (HNd
C). 15N NMR spectrum in CDCl3/DMSO-d6 (9:1) (through 1H,15N
HMQC experiment), δ: 85.3 (HNdC), 145.6 (ONH). 195Pt NMR
spectrum in CDCl3/DMSO-d6 (9:1), δ: -153 (700 Hz).
trans-[PtCl4{NHdC(Et)ON(H)CMe2C(Me)dNOH}2] (8). Anal.
Calcd for C16H34N6Cl4O4Pt: C, 27.01; H, 4.82; N, 11.81%.
Found: C, 27.51; H, 4.84; N, 10.79%. FAB+-MS, m/z: 710 [M]+,
641 [M - 2Cl + H]+. IR spectrum (selected bands), cm-1: 3232
mw ν(N-H), 1657 s ν(CdN). 1H NMR spectrum in DMSO-d6, δ:
1.11 (t, J ) 7.5 Hz, 3H, CH2Me), 1.23 (s, 6H, NCMe2), 1.79 (s,
3H, NdCMe), 2.95 (quart, J ) 7.2 Hz, 2H, CH2Me), 8.45 (s, 1H,
2
ONH), 9.06 (s + d, JPtH ca. 35 Hz, 1H, NH), 10.81 (s, 1H, Cd
Supporting Information Available: General view of the
equilibrium geometries, bond lengths, total energies, enthalpies, free
Gibbs energies, entropies, and Cartesian coordinates of the calcu-
lated structures; Tables S1-S6 listing crystallographic data, atomic
coordinates, bond lengths and bond angles, anisotropic displacement
parameters, hydrogen coordinates and isotropic displacement
parameters, and torsion angles. X-ray crystallographic files in CIF
format. This material is available free of charge via the Internet at
http://pubs.acs.org.
NOH). 13C{1H} NMR spectrum in DMSO-d6 (through direct 13C-
1
1
{1H} observation and H,13C HMQC, and H,13C HMBC experi-
ments), δ: 10.5 (NdCMe), 11.4 (CH3) and 24.8 (CH2)(Et), 23.3
(Me, NCMe2), 62.8 (NCMe2), 157.1 (ONdC), 179.5 (HNdC). 15
N
NMR spectrum in DMSO-d6 (through 1H,15N HMQC experiment),
δ: 83.9 (HNdC), 151.1 (ONH). 195Pt NMR spectrum in DMSO-
d6, δ: -92 (750 Hz).
Further Conversions of 5 and 6. Prolonged heating of 5 and 6
(45 °C, 12 h) obtained in situ (see above), followed by slow
evaporation of the solution for 1 day, results in the formation of
IC051909R
2306 Inorganic Chemistry, Vol. 45, No. 5, 2006