Kinetic and mechanistic study of the Pt(II) versus Pt(IV) effect in the platinum-mediated nitrile-hydroxylamine coupling

Article abstract of DOI:10.1021/ic048388c

The metal-mediated coupling between coordinated EtCN in the platinum(II) and platinum(IV) complexes cis- and trans-[PtCl₂(EtCN)₂], trans-[PtCl₄(EtCN)₂], a mixture of cis/trans-[PtCl ₄(EtCN)₂] or [Ph₃PCH₂Ph][PtCl _n(EtCN)] (n = 3, 5), and dialkyl- and dibenzylhydroxylamines R ₂NOH (R = Me, Et, CH₂Ph, CH₂C₆H ₄Cl-P) proceeds smoothly in CH₂Cl₂ at 20-25°C and the subsequent workup allowed the isolation of new imino species [PtCl_n{NH=C(Et)-ONR₂}₂] (n = 2, R = Me, cis-1 and trans-1; Et, cis-2 and trans-2; CH₂Ph, cis-3 and trans-3; CH ₂C₆H₄Cl-p, cis-4 and trans-4; n = 4, R = Me, trans-9; Et, trans-10; CH₂Ph, trans-11; CH₂C ₆H₄Cl-P, trans-12) or [Ph₃PCH ₂Ph]-[PtCl_n{NH=C(Et)ONR₂}] (n = 3, R = Me, 5; Et, 6; CH₂Ph, 7; CH₂C₆H₄Cl-P, 8; n = 5, R = Me, 13; Et, 14; CH₂Ph, 15; CH₂C₆H ₄Cl-p, 16) in excellent to good (95-80%) isolated yields. The reduction of the Pt(IV) complexes 9-16 with the ylide Ph₃P=CHCO ₂Me allows the synthesis of Pt(II) species 1-8. The compounds 1-16 were characterized by elemental analyses (C, H, N), FAB-MS, IR, ¹H, ¹³C(1H), and ³¹P{¹H} NMR (the latter for the anionic type complexes 5-8 and 13-16) and by X-ray crystallography for the Pt(II) (cis-1, cis-2, and trans-4) and R(IV) (15) species. Kinetic studies of addition of R₂NOH (R = CH₂C₆H₄Cl-p) to complexes [Ph₃PCH₂Ph]-[Pt^IICl ₃(EtCN)] and [Ph₃PCH₂Ph][Pt^IVCl ₅(EtCN)] by the ¹H NMR technique revealed that both reactions are first order in (p-ClC₆H₄CH₂) ₂NOH and Pt(II) or Pt(IV) complex, the second-order rate constant k₂ being three orders of magnitude larger for the Pt(IV) complex. The reactions are intermolecular in nature as proved by the independence of k ₂ on the concentrations of added EtC≡N and Cl^-. These data and the calculated values of ΔH^? and ΔS^? are consistent with the mechanism involving the rate-limiting nucleophilic attack of the oxygen of (p-ClC₆H ₄CH₂)₂NOH at the sp-carbon of the C≡N bond followed by a fast proton migration.

Full text of DOI:10.1021/ic048388c

Inorg. Chem. 2005, 44, 2944−2953
Kinetic and Mechanistic Study of the Pt(II) versus Pt(IV) Effect in the
Platinum-Mediated Nitrile Hydroxylamine Coupling
−
Konstantin V. Luzyanin,†,‡ Vadim Yu. Kukushkin,*,‡ Alexander D. Ryabov,*,§ Matti Haukka,| and
Armando J. L. Pombeiro*,†
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, AV. RoVisco Pais,
1049-001 Lisbon, Portugal, St. Petersburg State UniVersity, 198504 Stary Petergof,
Russian Federation, Department of Chemistry, Carnegie Mellon UniVersity, 4400 Fifth AVenue,
Pittsburgh, PennsylVania 15213, and Department of Chemistry, UniVersity of Joensuu,
P.O. Box 111, FIN-80101, Joensuu, Finland
Received November 16, 2004
The metal-mediated coupling between coordinated EtCN in the platinum(II) and platinum(IV) complexes cis- and
trans-[PtCl2(EtCN)2], trans-[PtCl4(EtCN)2], mixture of cis/trans-[PtCl4(EtCN)2] or [Ph3PCH2Ph][PtCln(EtCN)]
(n 3, 5), and dialkyl- and dibenzylhydroxylamines R2NOH (R Me, Et, CH2Ph, CH2C6H4Cl-p) proceeds smoothly
in CH2Cl2 at 20 25 C and the subsequent workup allowed the isolation of new imino species [PtCln NH C(Et)-
ONR2 2] (n 2, R Me, cis-1 and trans-1; Et, cis-2 and trans-2; CH2Ph, cis-3 and trans-3; CH2C6H4Cl-p, cis-4
and trans-4; n 4, R Me, trans-9; Et, trans-10; CH2Ph, trans-11; CH2C6H4Cl-p, trans-12) or [Ph3PCH2Ph]-
[PtCln NH C(Et)ONR2 ] (n 3, R Me, 5; Et, 6; CH2Ph, 7; CH2C6H4Cl-p, 8; n 5, R Me, 13; Et, 14;
CH2Ph, 15; CH2C6H4Cl-p, 16) in excellent to good (95 80%) isolated yields. The reduction of the Pt(IV) complexes
16 with the ylide Ph3P CHCO2Me allows the synthesis of Pt(II) species 1 8. The compounds 1 16 were
characterized by elemental analyses (C, H, N), FAB-MS, IR, 1H, 13C 1H , and 31P 1H
NMR (the latter for the
anionic type complexes 5 8 and 13 16) and by X-ray crystallography for the Pt(II) (cis-1, cis-2, and trans-4) and
Pt(IV) (15) species. Kinetic studies of addition of R2NOH (R CH2C6H4Cl-p) to complexes [Ph3PCH2Ph]-
a
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[PtIICl3(EtCN)] and [Ph3PCH2Ph][PtIVCl5(EtCN)] by the 1H NMR technique revealed that both reactions are first
order in (p-ClC6H4CH2)2NOH and Pt(II) or Pt(IV) complex, the second-order rate constant k2 being three orders of
magnitude larger for the Pt(IV) complex. The reactions are intermolecular in nature as proved by the independence
of k2 on the concentrations of added EtC
consistent with the mechanism involving the rate-limiting nucleophilic attack of the oxygen of (p-ClC6H4CH2)2NOH
at the sp-carbon of the C N bond followed by a fast proton migration.
t ∆ ∆
N and Cls. These data and the calculated values of Hq and Sq are
t
Introduction
transformations of other coordinated molecules. Metal-
mediated and/or metal-catalyzed reactions of RCN have been
surveyed in a number of articles1-7 including those written
by some of us.1-4
Recently, our group has been involved in studies of the
reactivity of metal-activated nitriles toward HON-nucleo-
Reactivity of ligated nitriles has been an area of continuous
interest for many years owing to their great industrial
potential (e.g., for preparation of acrylamide or nicotine-
amide) and a variety of laboratory applications (e.g., as
synthons of a broad range of imines and amides) for metal-
mediated RCN reactions. In addition, nitriles are isoelectronic
to other important species such as N2, CO, RNC, and alkynes,
and their behavior as ligands can model, to a certain degree,
(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 II; McCleverty,
J. A., Meter, T. J., Eds.; Elsevier: Amsterdam, 2004; Vol. 1, Chapter
1.34, pp 639-660.
(3) Kukushkin, V. Yu.; Pombeiro, A. J. L. Inorg. Chim. Acta 2005, 358,
1.
* Authors to whom correspondence should be addressed.
† Instituto Superior Te´cnico.
(4) Bokach, N. A.; Kukushkin, V. Yu. Uspekhi Khimii (Russ. Chem. ReV.)
‡ St. Petersburg State University.
§ Carnegie Mellon University.
2005, 74, 164.
(5) Michelin, R. A.; Mozzon, M.; Bertani, R. Coord. Chem. ReV. 1996,
147, 299.
| University of Joensuu.
2944 Inorganic Chemistry, Vol. 44, No. 8, 2005
10.1021/ic048388c CCC: $30.25
© 2005 American Chemical Society
Published on Web 03/18/2005

Platinum-Mediated Nitrile-Hydroxylamine Coupling
philes.4 It has been observed that reactions between
(RCN)[M] (M ) Pt(IV), Pt(II), Rh(III), Re(IV)) complexes
and HON-species such as “simple” oximes,8-14 Vic-di-
oximes,15 oximehydrazones,16 dialkyl hydroxylamines,17 and
hydroxamic acids18,19 lead to formation of a C-O{N} bond
upon addition of the OH group at the CtN moiety of metal-
activated RCN. It is worthwhile to notice that in the initial
stage of the project, the reactions between nitriles and HON-
nucleophiles observed at substitutionally inert metal com-
plexes (mostly of platinum group metals) had purely a basic
research character, whereas latersbeing performed at kineti-
cally labile metal centers (for instance, Co(III),20 Ni(II),21,22
and Zn(II)23,24)sthese systems acquired a more applied
character insofar as they opened up attractive routes to
syntheses of important classes of nitrile-derived organic
compounds such as amidines,20 acyl amides,21 imidoyl-
amidines,21 phthalocyanines22 and carboxamides.23,24 The
latter findings gave a new strong impact for further explora-
tion of the nitrile reactions with HON-type nucleophiles from
a combined viewpoint of their synthetic value, recognition
of general features, understanding of driving forces, and
estimate of activation effects by different metal centers.
As far as the latter effect is concerned, one should notice
that despite the wealth of kinetic data associated with
nucleophilic addition to ligated nitriles at diVerse metal
centers, the qualitative comparison of activation effect of
nitriles by one metal center in different oxidation states has
been done only for octahedral Ru(III) and Ru(II) complexes
in the hydration reaction;3 no kinetic data on systems of one
metal center in different oxidation states and different
polyhedra were obtained up to date.
Upon our study of the reaction between (nitrile)Pt com-
plexes and HONR2 (R ) alkyl, benzyl), we discovered that
hydroxylamines react with RCtN at both octahedral Pt(IV)
and square-planar Pt(II) centers of the structurally related
complexes [PtCln(RCN)]- (n ) 3, 5). This finding prompted
us to undertake a comprehensive synthetic, structural, and
kinetic study to verify the difference in the activation effect
between the complexes in the two oxidation states. All these
results are described in this article.
(6) Eglin, J. Comments Inorg. Chem. 2002, 23, 23. Murahashi, S. I.;
Takaya, H. Acc. Chem. Res. 2000, 33, 225. Kukushkin, Yu. N. Russ.
J. Coord. Chem. 1998, 24, 173. Parkins, A. W. Platinum Met. ReV.
1996, 40, 169. da Rocha, Z. N.; Chiericato, G., Jr.; Tfouni, E. AdV.
Chem. Ser. 1997, 297. Kuznetsov, M. L. Uspekhi Khimii (Russ. Chem.
ReV.) 2002, 71, 307.
(7) Constable, E. C. Metals and Ligand ReactiVity. An Introduction to
the Organic Chemistry of Metal Complexes; VCH: Weinheim, 1995;
p 65. Corain, B.; Basato, M.; Veronese, A. C. J. Mol. Catal. 1993,
81, 133. Chin, J. Acc. Chem. Res. 1991, 24, 145.
(8) Kukushkin, V. Yu.; Pakhomova, T. B.; Kukushkin, Yu. N.; Herrmann,
R.; Wagner, G.; Pombeiro, A. J. L. Inorg. Chem. 1998, 37, 6511.
(9) 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.
(10) Ferreira, C. M. P.; Guedes da Silva, M. F. C.; Frau´sto da Silva, J. J.
R.; Pombeiro, A. J. L.; Kukushkin, V. Yu.; Michelin, R. A. Inorg.
Chem. 2001, 40, 1134.
Results and Discussion
Starting Materials for Synthetic and Kinetic Studies.
The nitrile platinum(II) and platinum(IV) complexes
[Ph3PCH2Ph][PtCln(EtCN)] (n ) 3 I,11 5 II11) and cis- and
trans-[PtCln(EtCN)2] (n ) 2: cis-III and trans-III;25,26
n ) 4: a mixture of cis/trans-IV and trans-IV27) were
addressed for this study (starting materials are given in this
article in Roman numerals, whereas products are given in
Arabic numerals). The complex trans-[PtCl2(EtCN)2]
(trans-III) was prepared by solid-state heating of cis-
[PtCl2(EtCN)2]26 (cis-III) (route A). The chlorination of
trans-III leads to formation of the platinum(IV) complex
trans-[PtCl4(EtCN)2]27 (trans-IV) (route B). Interaction of
cis- or trans-III with [Ph3PCH2Ph]Cl allows the isolation
of [Ph3PCH2Ph][PtCl3(EtCN)]11 (I) (routes C1 and C2), and
chlorination of the latter results in the formation of
[Ph3PCH2Ph][PtCl5(EtCN)]11 (II) (route D).
(11) Kuznetsov, M. L.; Bokach, N. A.; Kukushkin, V. Yu.; Pakkanen, T.;
Wagner, G.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans. 2000,
4683.
(12) 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. Makarycheva-
Mikhailova, A. V.; Bokach, N. A.; Haukka, M.; Kukushkin, V. Yu.
Inorg. Chim. Acta (Special Volume dedicated to J. J. R. Frau´sto da
SilVa) 2003, 356, 382. Bokach, N. A.; Haukka, M.; Pombeiro, A. J.
L.; Morozkina, S. N.; Kukushkin, V. Yu. Inorg. Chim. Acta 2002,
336, 95.
(13) Wagner, G.; Pombeiro, A. J. L.; Bokach, N. A.; Kukushkin, V. Yu.
J. Chem. Soc., Dalton Trans. 1999, 4083.
(14) 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.
Kukushkin, V. Yu.; Ilichev, I. V.; Zhdanova, M. A.; Wagner, G.;
Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans. 2000, 1567.
(15) 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.
(16) Garnovskii, D. A.; Pombeiro, A. J. L.; Haukka, M.; Sobota, P.;
Kukushkin, V. Yu. Dalton Trans. 2004, 1097.
(17) Wagner, G.; Pombeiro, A. J. L.; Kukushkin, Yu. N.; Pakhomova, T.
B.; Ryabov, A. D.; Kukushkin, V. Yu. Inorg. Chim. Acta 1999, 292,
272.
Platinum-Mediated Nitrile-Hydroxylamine Coupling.
Hydroxylamine is an ambidentate nucleophile and its N- and
O- addition to nitriles is known in organic chemistry.28 In
the majority of cases, NH2OH adds to RCtN via its N atom
to form amidoximes, RC(NH2)dNOH, through the
(18) Luzyanin, K. V.; Kukushkin, V. Yu.; Kuznetsov, M. L.; Garnovskii,
D. A.; Haukka, M.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 2981.
(19) Luzyanin, K. V.; Kukushkin, V. Yu.; Haukka, M.; Frau´sto da Silva,
J. J. R.; Pombeiro, A. J. L. Dalton Trans. 2004, 2727.
(20) Kopylovich, M. N.; Kukushkin, V. Yu.; Guedes da Silva, M. F. C.;
Haukka, M.; Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L. J. Chem.
Soc., Perkin Trans. 1 2001, 1569.
(25) Kukushkin, V. Yu.; Oskarsson, A° .; Elding, L. I. Inorg. Synth. 1997,
31, 279.
(26) Svensson, P.; Lo¨vqvist, K.; Kukushkin, V. Yu.; Oskarsson, A° . Acta
Chem. Scand. 1995, 49, 72. Kukushkin, V. Yu.; Oskarsson, A° .; Elding,
L. I. Zh. Obsch. Khim. 1994, 64, 881; Russ. J. Gen. Chem. (Engl.
Transl.) 1994, 64, 793.
(21) Kopylovich, M. N.; Pombeiro, A. J. L.; Fischer, A.; Kloo, L.;
Kukushkin, V. Yu. Inorg. Chem. 2003, 42, 7239.
(27) Luzyanin, K. V.; Haukka, M.; Bokach, N. A.; Kuznetsov, M. L.;
Kukushkin, V. Yu.; Pombeiro, A. J. L. Dalton Trans. 2002, 1882.
(28) Eloy, F.; Lenaers, R. Chem. ReV. 1962, 62, 155. Zilberman, E. N.
Reactions of Nitriles (in Russian); Khimia: Moscow, 1972; p 166.
Dayagi, S.; Degani, Y. In The Chemistry of the Carbon-Nitrogen
Double Bond; Patai, S., Ed.; Interscience: London, 1970; p 111.
Judkins, B. D.; Allen, D. G.; Cook, T. A.; Evans, B.; Sardharwala, T.
E. Synth. Commun. 1996, 26, 4351.
(22) Kopylovich, M. N.; Kukushkin, V. Yu.; Haukka, M.; Luzyanin, K.
V.; Pombeiro, A. J. L. J. Am. Chem. Soc. 2004, 126, 15040.
(23) Kopylovich, M. N.; Kukushkin, V. Yu.; Haukka, M.; Frau´sto da Silva,
J. J. R.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 4798.
(24) Pombeiro, A. J. L.; Kukushkin, V. Yu.; Kopylovich, M. N.; Frau´sto
da Silva, J. J. R. Patent PT 102 618 P (priority date May 30, 2001).
Inorganic Chemistry, Vol. 44, No. 8, 2005 2945

Luzyanin et al.
Scheme 1
RC(dNH)NHOH intermediate.28 Very recently, it has been
established that the addition of dialkylhydroxylamines to
Pt(IV)-bound nitriles, in contrast to the reaction of hy-
droxyalmines with free nitriles, affords the imino species RC-
(dNH)ONR2 resulting from adding of the hydroxylamines
oxygen to RCtN, route I.17 Within the framework of the
current project this addition is now extended to, on one hand,
the anionic type Pt(IV) complex II, and, on the other hand,
to dibenzylhydroxylamines. Moreover, we also found that
the nitrile-hydroxylamine coupling is also mediated by the
Pt(II) center although less effectively as compared to the Pt-
(IV) one.
Thus, the coupling between Pt-bound nitriles in I, II, cis-
and trans-III, trans-IV, or a mixture of cis/trans-IV and
dialkyl- and dibenzylhydroxylamines R2NOH (R ) Me, Et,
CH2Ph, CH2C6H4Cl-p) proceeds smoothly in CH2Cl2 at
20-25 °C and the subsequent workup provides the new
imino species [PtCln{NHdC(Et)ONR2}2] (n ) 2, R ) Me,
cis-1 and trans-1; Et, cis-2 and trans-2; CH2Ph, cis-3 and
trans-3; CH2C6H4Cl-p, cis-4 and trans-4; n ) 4, R ) Me,
trans-9; Et, trans-10; CH2Phn trans-11; CH2C6H4Cl-p, trans-
12) or [Ph3PCH2Ph][PtCln{NHdC(Et)ONR2}] (n ) 3,
R ) Me, 5; Et, 6; CH2Ph, 7; CH2C6H4Cl-p, 8; n ) 5,
R ) Me, 13; Et, 14; CH2Ph, 15; CH2C6H4Cl-p, 16) in
excellent to good (95-80%) isolated yields. In the prepara-
tive experiments, the coupling proceeds faster for the
Pt(IV) species than for the Pt(II) compounds; neutral
complexes react faster than the corresponding anionic ones.
Thus, the formation of trans-[PtCl4{NHdC(Et)ONR2}2]
(9-12) in reaction I was achieved for ca. 5 min, the
C(Et)ONR2}] (5-8) in reaction G was accomplished for ca.
4-8 h. The absence of interaction between any of the studied
hydroxylamine and free EtCN (proved by H NMR) is in
1
accord with a metal-mediated coupling.
Treatment of 9-16 with Ph3PdCHCO2Me leads to the
reduction of the Pt(IV) center and allows the synthesis of
Pt(II) species 1-8 by routes H1 and H2, which are
alternative to G and F2, respectively.
Characterization of the Imino Complexes. Elemental
analyses (C, H, N), FAB-MS, IR, 1H, 13C{1H}, and 31P{1H}
NMR (the latter for the anionic type complexes 5-8 and
13-16) and X-ray data (see below) for the Pt(II) (cis-1, cis-
2, and trans-4) and Pt(IV) (15) species are in good agreement
with the proposed structures of Pt(II) and Pt(IV) complexes
with the newly formed imino ligands NHdC(Et)ONR2. In
IR spectra, the products of the reactions (1-16) show no
bands of ν(CtN) stretching vibrations in the range
2270-2400 cm-1 (note that such bands appear at 2340 cm-1
for trans-[PtCl4(EtCN)2]27 and 2314 cm-1 for trans-
[PtCl2(EtCN)2]25) but display intense bands in the range of
1660-1640 cm-1 assigned to ν(CdN) of the imino ligand
NHdC(Et)ONR2; these data are in a very good agreement
with those for similar complexes derived from the addition
of oximes (e.g., [PtCl2{NHdC(Me)ONdCMe2}2] or [PtCl4
{NHdC(Me)ONdCMe2}2]8-14), hydroxylamines (e.g., trans-
[PtCl4{NHdC(Me)ONEt2}2]17), and hydroxamic acids
(e.g., [PtCl4{NHdC(Et)ONdC(OH)(Ph)}2]18,19) to Pt-bound
nitriles. Furthermore, IR spectra of the anionic complexes
5-8 and 13-16 display the vibrations of very high intensity
at ca. 1110 cm-1 due to ν(P-C)11 from the cation
[Ph3PCH2Ph]+; these bands are also observed in the chloride
[Ph3PCH2Ph]Cl (1120 cm-1).
formation
of
[Ph3PCH2Ph][PtCl5{NHdC(Et)ONR2}]
(13-16) in reaction E was complete after ca. 15 min, and
the formation of cis- and trans-[PtCl2{NHdC(Et)ONR2}2]
(1-4) in reactions F1 and F2 was achieved for ca. 0.5-2 h,
whereas the generation of [Ph3PCH2Ph][PtCl3{NHd
1H NMR spectra of 1-16 display a broad peak in the range
δ 8.00-8.50 assigned to the imine hydrogen of the
NHdC(Et)ONR2 moiety involved in hydrogen bonding
2946 Inorganic Chemistry, Vol. 44, No. 8, 2005

Platinum-Mediated Nitrile-Hydroxylamine Coupling
Figure 3. Crystal structure of [Ph3PCH2Ph][PtCl5{NHdC(Et)ON(CH2-
Ph)2}] (15). The cation is omitted for clarity. Selected bond lengths (Å)
and angles (deg): Pt(1)-N(1) 2.039(12), Pt(1)-Cl(1) 2.298(3), Pt(1)-Cl-
(2) 2.320(3), Pt(1)-Cl(3) 2.318(3), Pt(1)-Cl(4) 2.318(4), Pt(1)-Cl(5)
2.315(4), N(1)-C(1) 1.301(16), C(1)-O(1) 1.350(15), N(1)-Pt(1)-Cl(1)
175.3(3), Cl(4)-Pt(1)-Cl(5) 179.09(15), Cl(2)-Pt(1)-Cl(3) 178.28(15),
Pt(1)-N(1)-C(1) 136.1(10), N(1)-C(1)-O(1) 119.5(13).
Figure 1. Crystal structure of cis-[PtCl2{NHdC(Et)ONMe2}] (cis-1).
2.3021(13), and cis-2 2.3041(9), 2.3046(8) Å] are the same
within 3σ and this indicates that the ground-state trans
influence is similar for the imine and chloride species. The
two CdN bonds in each complex are equal within 3σ
[1.254(7) and 1.275(7) Å for cis-1; 1.271(4) and 1.273(4) Å
for cis-2; 1.272(4) and 1.277(4) Å for trans-4] and they are
very close to the typical values of the CdN double bonds.29
Inspection of the N-H and NH‚‚‚N distances and values
of the H-N‚‚‚H angles in the imine ligands clearly indicates
that the E-configuration of these species is stabilized by the
N-H‚‚‚H hydrogen bond between the imine hydrogen and
the hydroxylamine N atom with the following observed
distances and angles: N(1)-H(01) 0.95(7) Å, N(1)-H(01)‚
‚‚N(2) 2.20(2) Å, N(1)-H(01)‚‚‚N(2) 105(6)°, N(3)-H(03)
0.96(6) Å, N(3)-H(03)‚‚‚N(4) 2.14(6) Å, N(3)-H(03)‚‚‚
N(4) 109(5)° cis-1; N(1)-H(01) 0.89 Å, N(1)-H(01)‚‚‚N(2)
2.28 Å, N(1)-H(01)‚‚‚N(2) 107.8°, N(3)-H(03) 0.99 Å,
N(3)-H(03)‚‚‚N(4) 2.06 Å, N(3)-H(03)‚‚‚N(4) 117.5° cis-
2; and N(1)-H(01) 0.88(4) Å, N(1)-H(01)‚‚‚N(2) 2.15(3)
Å, N(1)-H(01)‚‚‚N(2) 115(3)°, N(3)-H(03) 0.84(4) Å,
N(3)-H(03)‚‚‚N(4) 2.24(3) Å, N(3)-H(03)‚‚‚N(4) 112(3)°
for trans-4. This H-bonding was also observed in the relevant
complexes trans-[PtCl4{NHdC(Me)ONdCR}2]8 and trans-
[PtCl4{NHdC(Me)ONR2}2].17
Figure 2. Crystal structure of trans-[PtCl2{NHdC(Et)ON(CH2C6H4Cl-
p)}2] (trans-4).
(found also in the solid-state molecular structures, see later)
and these data correspond well to those for the similar imino
complexes, e.g., [PtCln{NHdC(R)R′}2] (R′ ) ONR2′′,
17 ONdCR2′′,8-14 OHNC(dO)R′′18,19). 13C{1H} NMR spectra
of 1-16 display no signal of the CtN group from the
starting material (typically it emerges in the range 115-
125 ppm; e.g., 119 ppm for trans-[PtCl4(EtCN)2]27) but show
the signal from the CdN group in the range of 160-
170 ppm. The position of the latter peak is similar to that
observed for trans-[PtCl4{NHdC(Me)ONMe2}2].17
X-ray Structure Determinations. The X-ray structure
determinations have been performed for four compounds,
i.e., cis-[PtCl2{NHdC(Et)ONMe2}] (cis-1), cis-[PtCl2-
{NHdC(Et)ONEt2}] (cis-2), trans-[PtCl2{NHdC(Et)-
ON(CH2C6H4Cl-p)2] (trans-4), and [Ph3PCH2Ph][PtCl5-
{NHdC(Et)ON(CH2Ph)2}] (15) (Figures 1-3 and Tables 1
and 2). The coordination polyhedra of the three Pt(II)
complexes are slightly distorted square-planar and the imino
ligands are mutually cis for cis-1, cis-2 and trans for trans-4
and are in the E-configuration.
In 15 (see Figure 3), all bond lengths and angles are normal
and agree well with those in the previously studied neutral
(imino)Pt(IV) complexes trans-[PtCl4{NHdC(Me)ONR2}2]
(Figure 3).17
Kinetics of the Nucleophilic Addition. The structural-
ly related platinum(II) and platinum(IV) complexes
[Ph3PCH2Ph][PtCln(EtCN)] I (n ) 3) and II (n ) 5),
respectively, are well soluble in CDCl3 and have been
1
selected for the kinetic investigation using the H NMR
technique. They contain only one nitrile ligand and are more
appropriate for collecting and interpreting kinetic data as
compared to the more common bis-nitrile complexes
[PtCln(RCN)2], where two consecutive processes should be
The Pt-Cl and Pt-N bond lengths and also all bond
angles around the Pt center are normal and they are in a
good agreement with those for the related complexes, trans-
[PtCl2{NHdC(Et)ONdC(Me)C(Me)(dO)}2]12 and trans-
[PtCl2{NHdC(Me)ONdCMe2}2].9 The Pt-Cl bond dis-
tances in the complexes with the trans [trans-4 2.2982(8),
2.3069(8) Å] and cis configurations [cis-1 2.3018(12),
1
taken into account. In addition, the H NMR spectra of
[PtCln(EtCN)]- are less complicated as compared with those
of the bis-nitrile compounds and this allows an accurate
integration of the signals from the Et groups of the starting
(29) 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. 44, No. 8, 2005 2947

Luzyanin et al.
Table 1. Crystallographic Data for cis-1, cis-2, trans-4, and 15
cis-1
cis-2
trans-4
15
empirical formula
fw
temp (K)
λ (Å)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C10H24N4Cl2O2Pt
498.32
110(2)
0.71073
triclinic
P1h
8.2530(15)
9.9420(12)
10.670(2)
103.695(10)
91.346(15)
92.089(13)
1793.68(8)
2
1.741
4.396
8293
3196
0.0300
0.0724
C14H32N4Cl2O2Pt
554.43
110(2)
0.71073
monoclinic
P21/c
11.2917(16)
13.2252(15)
14.9965(14)
90
99.251(11)
90
2210.4(5)
4
1.666
6.602
C34H36N4Cl6O2Pt
940.46
100(2)
0.71073
monoclinic
P21
13.1961(4)
10.3787(2)
13.3755(4)
90
101.7230(10)
90
1793.68(8)
2
1.741
4.396
C42H42N2Cl5OPPt
994.09
150(2)
0.71073
orthorhombic
Pbca
10.0914(7)
19.504(2)
42.279(5)
90
90
90
8321.3(15)
8
1.587
3.767
16000
4383
0.0570
0.1107
Z
F
calc (Mg/m3)
µ(Mo KR) (mm-1
)
no. of collected reflns
no. of unique rflns
R1a(I g 2σ)
29451
5073
0.0221
0.0406
27046
8162
0.0195
0.0457
wR2b(I g 2 σ)
2
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) [∑[w(Fo - Fc )2]/∑[w(Fo )2]]1/2
.
Table 2. Selected Bond Lengths and Angles for the Platinum(II)
Complexes cis-1, cis-2, and trans-4
cis-1
cis-2
trans-4
Pt(1)-Cl(1)
Pt(1)-Cl(2)
Pt(1)-N(1)
Pt(1)-N(3)
N(1)-C(1)
N(3)-C(6)
N(3)-C(8)
N(3)-C(18)
2.3018(12)
2.3021(13)
2.020(4)
2.015(4)
1.254(7)
1.275(7)
2.3041(8)
2.3047(8)
2.020(2)
2.014(2)
1.271(4)
2.2982(8)
2.3068(8)
2.020(3)
2.015(3)
1.272(4)
1.273(4)
1.277(4)
Cl(1)-Pt(1)-Cl(2)
N(1)-Pt(1)-N(3)
Pt(1)-N(1)-C(1)
Pt(1)-N(3)-C(6)
Pt(1)-N(3)-C(8)
Pt(1)-N(3)-C(18)
92.75(5)
93.4(2)
127.7(3)
129.3(3)
91.94(3)
90.67(10)
127.9(2)
178.73(3)
178.29(11)
126.9(2)
Figure 4. Pseudo-first-order rate constants kobs as a function of [DAH]
for reactions 1 (O) and 2 (b) at 40.0 and -20.0 °C, respectively, in CDCl3
as solvent; [I] ) [II] ) 1.35 × 10-3 M.
128.8(2)
129.0(2)
presence of a large excess of free propionitrile. Indeed, the
same values of k2 have been obtained in the presence of 100-
fold excess of EtCN relative to I or II. Free propionitrile
does not react with DAH in chloroform even under harsh
conditions (1 week at 45 °C).
In principle, reactions 1 and 2 could involve a reversible
substitution of chloride by DAH followed by an intra-
molecular nucleophilic attack at the coordinated nitrile.
Therefore, the effect of chloride on k2 has been tested
by the example of reaction 1 at 40 °C. Addition of
[Ph3PCH2Ph]Cl does not practically affect the rate constants
and k2 equals 0.77 ( 0.01, 0.73 ( 0.04, and 0.70 (
0.03 M-1 s-1 at [Cl-] ) 0.0, 0.013, and 0.135 M, respec-
tively. We could not measure the effect of chloride on the
rate of reaction 2 due to the substitution of EtCN by chloride
that occurs via eq 4.
material and the product. Complexes I and II react via eqs
1 and 2 (Scheme 2), respectively, which are again rather
similar but the reactivity of I is significantly lower than that
of II.
Major kinetic data for complexes I and II have been
obtained at different temperatures, viz. -20.0 and 40.0 °C,
respectively. Under such conditions, the reactions are
complete in a matter of 0.5-1 h. A satisfactory pseudo-first-
order behavior has been observed for both complexes in the
presence of an excess of the hydroxylamine (p-ClC6H4CH2)2-
NOH (DAH). A first order in complexes I and II holds for
at least 3-5 half-lives. The dependences of pseudo-first-
order rate constants kobs against the concentration of DAH
indicate a first order in the incoming nucleophile for I and
II without any significant intercept (Figure 4). Thus, reactions
1 and 2 follow the same rate law 3.
II + [Ph3PCH2Ph]Cl f [Ph3PCH2Ph]2[PtCl6] + EtCN (4)
kobs ) k2[DAH]
(3)
The second-order rate constants k2 have been obtained at
different temperatures (Table 3) and these data have been
used for calculating the corresponding activation parameters
∆Hq and ∆Sq for reactions 1 and 2, which are also included
in Table 3. The rate constants k2 are unaffected by the
Ligand substitution reaction 4 involves the Pt(IV) complex
and a nucleophile (Cl-). The observation that complex II
reacts with chloride but complex I does not is in accordance
with the fact that the Pt(IV) complex is more electrophilic
and therefore the reactivity of II is also higher with respect
2948 Inorganic Chemistry, Vol. 44, No. 8, 2005

Platinum-Mediated Nitrile-Hydroxylamine Coupling
Scheme 2
Table 3. Kinetic and Activation Parameters for Reactions 1 and 2 in CDCl3
T/°C
[DAH]/M
kobs/s-1
k2/M-1 s-1
∆Hq/kJ mol-1
56 ( 6
∆Sq/J mol-1 K-1
-47 ( 23
Reaction 2
-30.0
-20.0
5.38 × 10-2
(8.1 ( 0.4) × 10-4
(1.5 ( 0.1) × 10-2
(6.1 ( 0.4) × 10-2
1.08 × 10-2
1.35 × 10-2
2.69 × 10-2
5.38 × 10-2
1.08 × 10-1
(5.9 ( 0.3) × 10-4
(8.1 ( 0.4) × 10-4
(1.7 ( 0.1) × 10-3
(3.0 ( 0.2) × 10-3 a
(6.7 ( 0.3) × 10-3
-15.0
-10.0
5.38 × 10-2
5.38 × 10-2
(4.1 ( 0.4) × 10-4
(7.5 ( 0.3) × 10-3
(7.7 ( 0.4) × 10-2
(1.4 ( 0.1) × 10-1
Reaction 1
20.0
30.0
40.0
5.38 × 10-2
5.38 × 10-2
(1.1 ( 0.2) × 10-4
(3.5 ( 0.4) × 10-4
(2.2 ( 0.1) × 10-3
(6.5 ( 0.3) × 10-3
(1.9 ( 0.1) × 10-2
74 ( 3
-41 ( 10
1.08 × 10-2
2.01 × 10-2
2.69 × 10-2
5.38 × 10-2
1.08 × 10-1
(2.1 ( 0.1) × 10-4
(3.8 ( 0.2) × 10-4
(4.8 ( 0.2) × 10-4
(1.0 ( 0.1) × 10-3 b
(1.9 ( 0.1) × 10-3
50.0
5.38 × 10-2
(2.1 ( 0.2) × 10-3
(4.0 ( 0.2) × 10-2
a (3.5 ( 0.2) × 10-3 s-1 for (PhCH2)2NOH. b (1.28 ( 0.07) × 10-3 s-1 for (PhCH2)2NOH.
to the hydroxylamine nucleophile DAH. Limited data
obtained for (PhCH2)2NOH as a nucleophile (see footnote
to Table 3) indicate that this more nucleophilic hydro-
xylamine reacts somewhat faster as compared to
(p-ClC6H4CH2)2NOH (DAH), as could be anticipated.
The addition of hydroxylamines to nitriles coordinated to
Pt(II) and Pt(IV) is a true nucleophilic reaction where the
platinum centers enhance immensely the reactivity of pro-
pionitrile. The kinetic data suggest that it is always the
coordinated nitrile that reacts with the hydroxylamine and
the nucleophilic attack occurs from the bulk solution. Clear
first-order kinetics in hydroxylamine for both Pt(II) and
Pt(IV) complexes (Figure 4) and the absence of inhibition
by added chloride agrees with the fact that hydroxylamine
does not coordinate platinum(II) or (IV) before the addition
across the CtN bond. In other words, reactions 1 and 2 are
true intermolecular processes. The negative values of en-
tropies of activation ∆S‡ (Table 3) agree with the bimolecular
character of the reactions.30,31 The more nucleophilic dibenzyl
hydroxylamine reacts somewhat faster than DAH supporting
the nucleophilic nature of the reactions.
The platinum(IV) complex II is notably more reactive than
its platinum(II) counterpart I. The difference in the reactivity
of compounds II and I leads to faster kinetics (k2) in the
former by a factor of 1.4 × 103 at 0 °C. The k2 ratio was
calculated by using the values of activation parameters from
Table 3. Recent theoretical studies32 suggest that although
nitriles exhibit both weak σ-donor and π-acceptor properties,
the σ-donor features prevail even for the Pt(II) complexes.
An increase in the oxidation state of platinum from II to IV
results in a stronger shift of the electron density from the
ligand to the metal. Hence, the nitrile should be more
electron-deficient in complex II and this facilitates the
nucleophilic attack at the ligand bound to Pt(IV). Analysis
(31) Wilkins, R. G. Kinetics and Mechanism of Reactions of Transition
Metal Complexes, 2nd ed.; VCH: Weinheim, 1991.
(32) Kuznetsov, M. L. J. Mol. Struct., THEOCHEM 2004, 674, 33.
Kuznetsov, M. L.; Kukushkin, V. Yu.; Haukka, M.; Pombeiro, A. J.
L. Inorg. Chim. Acta 2003, 356, 85. Kuznetsov, M. L.; Dement’ev,
A. I.; Shestakova, O. S.; Kukushkin, V. Yu. Russ. J. Inorg. Chem.
2001, 46, 1683.
(30) Espenson, J. H. Chemical Kinetics and Reaction Mechanisms, 2nd
ed.; McGraw-Hill: New York, 1995.
Inorganic Chemistry, Vol. 44, No. 8, 2005 2949

Luzyanin et al.
of the frontier molecular orbitals of the dinitrile complexes
trans-[PtCl2(NCMe)2] and trans-[PtCl4(NCMe)2]11,32 indi-
cates that the energy of the empty π*(CN) MO in the
Pt(IV) complex is lower as compared with the Pt(II) species.
Thus, the higher reactivity of the Pt(IV) species can also be
accounted for in terms of the frontier orbital energy differ-
ence. Note the free energy of activation ∆Gq that can be
calculated from the data in Table 3 is by 16 kJ mol-1
(at 0 °C) lower in reaction 2 involving the Pt(IV) species.
The general mechanism of addition of hydroxylamines to
nitriles coordinated to Pt(II) and Pt(IV) complexes should
involve the rate-limiting nucleophilic attack of the hydroxy-
lamine oxygen at the sp-carbon of the CtN group of
coordinated nitrile followed by a fast proton migration. It is
interesting to note that ligand substitution at Pt(II) and
Pt(IV) centers generally occurs via different mechanisms,
i.e., associative and dissociative, respectively.31 Our study
has shown that the kinetic features of reactions 1 and 2 are
strikingly similar. This may indicate that ligand substitution
is not involved in these processes, thus supporting the
suggested mechanism.
whereas they are unreactive when treated with (nitrile)
Pt(II) species;11 (ii) alcohols33 or water3 react easily with
(nitrile)Pt(IV) complexes without added OH-, whereas these
reactions with (nitrile)Pt(II) complexes require the addition
of an alkali to perform the addition. On the other hand, the
kinetic data also suggest that synthetic chemists could take
advantage of the stronger electrophilic activation power of
a Pt(IV) center of RCN ligands to form, upon addition
followed by reduction, final (imine)Pt(II) complexes which
otherwise would not be accessible.
Experimental Section
Materials and Instrumentation. Hydroxylamines were pur-
chased from Aldrich. 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 TLC, Merck UV 254 SiO2-plates have been used.
Positive-ion 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. 1H, 13C{1H}, and 31P{1H} NMR
spectra were measured on a Varian UNITY 300 spectrometer at
ambient temperature.
Final Remarks
QualitatiVely the activation effect of a metal center toward
the nucleophlic attack at the coordinated RCN can be
estimated by analyzing IR spectra of free and ligated nitriles.
Thus, the ν(CtN) stretching vibrations of (nitrile)Pt(II)
complexes exhibit positive coordination shift values of
∆ν ) ν(CtN)coord - ν(CtN)free ≈ 50 cm-1 indicating5 the
increased electrophilic susceptibility of the nitrile carbon.
Moreover, this shift is even more positive on going from
platinum(II) to the relevant platinum(IV) species [e.g.,
ν(CtN) 2314 and 2340 cm-1 for trans-[PtCln(EtCN)2]25,27
(n ) 2, 4), respectively] and this comparison favors the
higher activation of RCN, toward the nucleophilic attack,
by a Pt(IV) center. In general, the nucleophilic additions to
Pt(II)- and Pt(IV)-bound nitriles proceed under strictly
different conditions1,4,8,33 and this hampered the qualitative
comparison of the activation effect by the two Pt metal
centers.
In the current work, we discovered that the coupling
between EtCN and R2NOH proceeds in a similar way, albeit
with substantially different rates, in the structurally related
platinum(II) and platinum(IV) complexes [Ph3PCH2Ph]-
[PtCln(EtCN)] (n ) 3, 5). This finding prompted further
kinetic study and, eventually, allowed the first quantitatiVe
comparison of the activation effect of the Pt centers in
different oxidation states toward RCN species. The actual
activating effect of nitriles by Pt(IV) versus Pt(II) is 3 orders
of magnitude when coordinated propionitrile reacts with
(p-ClC6H4CH2)2NOH. This reactivity difference, on one
hand, explains the previous preparative observations, i.e.,
(i) weak HO-nucleophiles such as oximes, under mild
conditions, react with RCN in (nitrile)Pt(IV) complexes,
Synthetic Work. Addition of R2NOH to [PtCl2(EtCN)2]. In a
typical experiment, the isomerically pure trans-III (0.10 g,
0.266 mmol) [or a mixture of cis/trans-III] which contains, by NMR
and TLC, ca. 80% of the cis isomer25,26] is dissolved in chloroform
(5 mL) at 20-25 °C, the hydroxylamine (0.522 mmol) is added,
and the reaction mixture is left to stand for 3 h at room temperature.
The bright yellow solution is evaporated to dryness at room
temperature under a flow of N2 and the solid residue is washed
with diethyl ether (five 3-mL portions) to remove the excess of
the hydroxylamine. Yields are 95-90%, based on Pt. In the case
of trans-III only the isomerically pure trans-[PtCl2{NHdC(Et)-
ONR2}2] was isolated, otherwise the mixture of cis/trans isomers
was obtained. In the latter case, the isomers were separated by
chromatography on SiO2.
trans-[PtCl2{NHdC(Et)ONMe2}2] (trans-1). Anal. Calcd for
C10H24N4Cl2O2Pt: C, 24.10; H, 4.85; N, 11.24%. Found: C, 24.05;
H, 4.80; N, 11.00%. FAB-MS, m/z: 498 [M]+, 463 [M - Cl]+,
427 [M - 2Cl]+. IR spectrum (selected bands), cm-1: 3225 mw
ν(N-H), 1661 s ν(CdN), 1438 s ν(CdC), 750 s δ(C-H). 1H NMR
spectrum in CDCl3, δ: 1.37 (t, J ) 7.5 Hz, 3H, CH2Me), 2.76
(s, 6H, NMe), 2.92 (q, J ) 7.5 Hz, 2H, CH2Me), 8.05 (s, br, 1H,
NH). 13C{1H} NMR spectrum in CDCl3, δ: 10.2 (CH3), 21.1 (CH2)-
(Et), 47.2 (Me, NMe), 176.5 (HNdC).
cis-[PtCl2{NHdC(Et)ONMe2}2] (cis-1). Anal. Calcd for
C10H24N4Cl2O2Pt: C, 24.10; H, 4.85; N, 11.24%. Found: C, 24.00;
H, 4.84; N, 11.20%. FAB-MS, m/z: 498 [M]+, 463 [M - Cl]+,
427 [M - 2Cl]+. IR spectrum (selected bands), cm-1: 3225 mw
ν(N-H), 1661 s ν(CdN), 1438 s ν(CdC), 750 s δ(C-H). 1H NMR
spectrum in CDCl3, δ: 1.27 (t, J ) 7.5 Hz, 3H, CH2Me), 2.73
(s, 6H, NMe), 2.92 (q, J ) 7.5 Hz, 2H, CH2Me), 8.15 (s, br, 1H,
NH). 13C{1H} NMR spectrum in CDCl3, δ: 10.2 (CH3), 21.1 (CH2)-
(Et), 47.2 (Me, NMe), 176.5 (HNdC).
trans-[PtCl2{NHdC(Et)ONEt2}2] (trans-2). Anal. Calcd for
C14H32N4Cl2O2PPt: C, 30.33; H, 5.82; N, 10.11%. Found: C, 30.40;
H, 6.18; N, 9.97%. FAB-MS, m/z: 554 [M]+, 519 [M - Cl]+, 483
[M - 2Cl]+. IR spectrum (selected bands), cm-1: 3189 m-w
ν(N-H), 1661 s ν(CdN), 1438 m ν(CdC). 1H NMR spectrum in
(33) Bokach, N. A.; Kukushkin, V. Yu.; Kuznetsov, M. L.; Garnovskii,
D. A.; Natile, G.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 2041.
Cini, R.; Caputo, P. A.; Intini, F. P.; Natile, G. Inorg. Chem. 1995,
34, 1130.
2950 Inorganic Chemistry, Vol. 44, No. 8, 2005

Platinum-Mediated Nitrile-Hydroxylamine Coupling
CDCl3, δ: 1.01 (t, J ) 7.5 Hz, 6H, NCH2Me), 1.30 (t, J ) 7.5 Hz,
3H, CH2Me), 2.92-2.97 (m, 4H, NCH2Me and 2H, CH2Me), 8.14
(s, br, 1H, NH). 13C{1H} NMR in CDCl3, δ: 10.2 (CH3) and 26.4
(CH2)(Et), 11.7 (CH3) and 62.4 (CH2)(NEt), 175.7 (HNdC).
washed with diethyl ether (five 3-mL portions) to remove the excess
of the hydroxylamine. Yields are 80-90%, based on Pt.
[Ph3PCH2Ph][PtCl3{NHdC(Et)ONMe2}] (5). Anal. Calcd for
C30H34N2Cl3OPPt: C, 46.73; H, 4.44; N, 3.63%. Found: C, 46.53;
H, 4.54; N, 3.43%. FAB+-MS, m/z: 353 [Mcation], 262 [Mcation
-
cis-[PtCl2{NHdC(Et)ONEt2}2] (cis-2). Anal. Calcd for C14H32N4-
Cl2O2PPt: C, 30.33; H, 5.82; N, 10.11%. Found: C, 43.79; H, 4.31;
N, 3.24%. FAB-MS, m/z: 554 [M]+, 519 [M - Cl]+, 483
[M - 2Cl]+. IR spectrum (selected bands), cm-1: 3189 m-w
ν(N-H), 1661 s ν(CdN), 1438 m ν(CdC). 1H NMR spectrum in
CDCl3, δ: 1.01 (t, J ) 7.5 Hz, 6H, NCH2Me), 1.30 (t, J ) 7.5 Hz,
3H, CH2Me), 2.92-2.97 (m, 4H, NCH2Me and 2H, CH2Me), 8.14
(s, br, 1H, NH). 13C{1H} NMR in CDCl3, δ: 10.2 (CH3) and 26.4
(CH2)(Et), 11.7 (CH3) and 62.4 (CH2)(NEt), 175.7 (HNdC).
CH2Ph]. FAB- -MS, m/z: 417 [Manion], 347 [Manion - 2Cl]. IR
spectrum (selected bands), cm-1
:
3225 mw ν(N-H), 1652 s
ν(CdN), 1438 s ν(CdC), 1111 s ν(P-C), 750 s δ(C-H). 1H NMR
spectrum in CDCl3, δ: 1.14 (t, J ) 7.5 Hz, 3H, CH2Me), 2.82
(q, J ) 7.5 Hz, 2H, CH2Me), 3.09 (s, 3H, NMe), 4.91
2
(d, JPH ) 13.8 Hz, 2H, PCH2Ph), 6.97-7.29 and 7.53-7.74
(m, CH, Ph), 8.20 (s, br, 1H, NH). 13C{1H} NMR spectrum in
CDCl3, δ: 10.2 (CH3), 21.1(CH2)(Et), 30.8 (CH2, 1JPC ) 47.7 Hz,
PCH2Ph), 47.2 (Me, NMe), 116.6, 117.7, 126.7, 128.5, 128.8, 130.1,
130.2, 131.2, 134.1, and 135.0 (aryls), 176.5 (HNdC). 31P{1H}
NMR in CDCl3, δ: 23.2.
trans-[PtCl2{NHdC(Et)ON(CH2Ph)2}2] (trans-3). Anal. Calcd
for C34H40N4Cl2O2Pt: C, 50.87; H, 5.02; N, 6.98%. Found: C,
50.00; H, 5.02; N, 6.83%. FAB-MS, m/z: 641 [M]+, 569
[M - 2Cl]+. IR spectrum (selected bands), cm-1
: 3197 s
[Ph3PCH2Ph][PtCl3{NHdC(Et)ONEt2}] (6). Anal. Calcd for
ν(N-H), 1658 vs ν(CdN), 1435 m ν(CdC), 754 s δ(C-H).
1H NMR spectrum in CDCl3, δ: 1.02 (t, J ) 7.5 Hz, 3H, CH2Me),
2.75 (q, J ) 7.5 Hz, 2H, CH2Me), 3.98 and 4.06 (d, J ) 13.2 Hz,
4H, CH2Ph), 7.27-7.39 (m, 5H, CH, Ph), 8.10 (s, br, 1H, NH).
13C{1H} NMR in CDCl3, δ: 10.0 (CH3) and 25.8 (CH2)(Et), 62.4
(CH2, NCH2C6H5), 128.3, 128.7, 129.7, and 134.0 (aryls), 174.0
(HNdC).
C32H38N2Cl3OPPt: C, 48.10; H, 4.79; N, 3.51%. Found: C, 48.01;
H, 4.78; N, 3.41%. FAB+-MS, m/z: 353 [Mcation], 262 [Mcation
-
CH2Ph]. FAB- -MS, m/z: 410 [Manion - Cl], 339 [Manion - 3Cl].
IR spectrum (selected bands), cm-1: 3220 m-w ν(N-H), 1663 s
ν(CdN), 1437 s ν(CdC), 1111 s ν(P-C), 748 m δ(C-H). 1H NMR
spectrum in CDCl3, δ: 1.14 (t, J ) 7.5 Hz, 6H, NCH2Me), 1.24
(t, J ) 7.5 Hz, 3H, CH2Me), 2.96 (q, J ) 7.5 Hz, 4H, NCH2Me),
2
3.11 (q, J ) 7.5 Hz, 2H, CH2Me), 5.00 (d, JPH ) 13.5 Hz, 2H,
cis-[PtCl2{NHdC(Et)ON(CH2Ph)2}2] (cis-3). Anal. Calcd for
C34H40N4Cl2O2Pt: C, 50.87; H, 5.02; N, 6.98%. Found: C, 50.00;
H, 5.02; N, 6.83%. FAB-MS, m/z: 641 [M]+, 569 [M - 2Cl]+. IR
PCH2Ph), 7.05-7.82 (m, CH, Ph), 8.15 (s, br, 1H, NH). 13C{1H}
NMR spectrum in CDCl3, δ: 10.9 (CH2Me), 11.7 (NCH2Me), 24.1
1
spectrum (selected bands), cm-1
: 3197 s ν(N-H), 1658 vs
(CH2Me), 31.5 (CH2, JPC ) 47.6 Hz, PCH2Ph), 52.9 (NCH2Me),
1
116.8, 117.9, 128.4, 128.8, 130.4, 131.6, 134.4, 135.0 (Ph), 177.6
(HNdC). 31P{1H} NMR in CDCl3, δ: 28.4.
[Ph3PCH2Ph][PtCl3{NHdC(Et)ON(CH2Ph)2}] (7). Anal. Cal-
cd for C42H42N2Cl3OPPt: C, 54.64; H, 4.59; N, 3.03%. Found: C,
54.54; H, 4.57; N, 3.00%. FAB+-MS, m/z: 353 [Mcation], 262 [Mcation
- CH2Ph]. FAB- -MS, m/z: 569 [Manion], 534 [Manion - Cl]. IR
ν(CdN), 1435 m ν(CdC), 754 s δ(C-H). H NMR spectrum in
CDCl3, δ: 0.86 (t, J ) 7.5 Hz, 3H, CH2Me), 1.93 (q, J ) 7.5 Hz,
2H, CH2Me), 3.94 and 4.02 (m, J ) 12.6 Hz, 4H, CH2Ph), 7.27-
7.30 (m, 5H, Ph), 8.15 (s, br, 1H, NH). 13C{1H} NMR in CDCl3,
δ: 9.7 (CH3) and 25.3 (CH2)(Et), 61.8 (CH2, NCH2C6H5), 128.3,
128.7, 129.7, and 134.0 (aryls), 174.0 (HNdC).
spectrum (selected bands), cm-1
: 3222 mw ν(N-H), 1664 s
trans-[PtCl2{NHdC(Et)ON(CH2C6H4Cl-p)2}2] (trans-4). Anal.
Calcd for C34H36N4Cl6O2Pt: C, 43.42; H, 3.86; N, 5.96%. Found:
C, 43.24; H, 4.20; N, 5.89%. FAB-MS, m/z: 942 [M + 2H], 867
[M - 2Cl - H], 604 [M - L + 2H]. (eluent CH2Cl2). IR spectrum
(selected bands), cm-1: 3274 mw ν(N-H), 1661 s ν(CdN), 1433
ν(CdN), 1437 s ν(CdC), 1111 s ν(P-C), 749 s δ(C-H). 1H NMR
spectrum in CDCl3, δ: 0.85 (t, J ) 7.5 Hz, 3H, CH2Me), 2.91
(q, J ) 7.5 Hz, 2H, CH2Me), 4.08 (s, 4H, NCH2Ph), 5.00
2
(d, JPH ) 13.5 Hz, 2H, PCH2Ph), 7.04 (m, 2H, ortho), 7.15
1
s ν(CdC). H NMR spectrum in CDCl3, δ: 1.02 (t, J ) 7.5 Hz,
(m, 2H) and 7.24 (m, 1H)(PCH2Ph), 7.30-7.42 (m, 10H, NCH2Ph),
7.58-7.70 (m, 12H) and 7.78 (m, 3H)(Ph), 8.20 (s, br, 1H, NH).
13C{1H} NMR in CDCl3, δ: 10.5 (CH3) and 24.0 (CH2)(Et), 31.5
3H, CH2Me), 2.74 (q, J ) 7.5 Hz, 2H, CH2Me), 3.94 and 4.03
(d, J ) 13.8 Hz, 4H, CH2C6H4Cl-p), 7.22 and 7.35 (d, J ) 7.5 Hz,
4H, aryl), 8.03 (s, br, 1H, NH).13C{1H} NMR in CDCl3, δ: 10.2
(CH3) and 25.8 (CH2)(Et), 61.8 (CH2, NCH2C6H4Cl-p), 128.5,
129.1, 131.3, 132.1, 132.3, and 134.4 (aryls), 174.2 (HNdC).
1
(CH2, JPC ) 47.7 Hz, PCH2Ph), 61.4 (CH2, NCH2Ph), 117.5
(Cipso, 1JPC ) 86.1 Hz, Ph), 126.9 (Cipso, 2JPC ) 8.9 Hz, PCH2Ph),
128.1 (CH, NCH2Ph), 128.5 (CHp, JPC ) 2.8 Hz, PCH2Ph), 128.8
(CH, NCH2Ph), 128.9 (CHm, JPC ) 3.4 Hz, PCH2Ph), 129.8 (CH,
cis-[PtCl2{NHdC(Et)ON(CH2C6H4Cl-p)2}2] (cis-4). Anal. Cal-
cd for C34H36N4Cl6O2Pt: C, 43.42; H, 3.86; N, 5.96%. Found: C,
43.24; H, 4.20; N, 5.89%. FAB-MS, m/z: 942 [M + 2H]+, 867 [M
- 2Cl - H]+, 604 [M - L + 2H]+. IR spectrum (selected bands),
NCH2Ph), 130.3 (CH, JPC ) 11.9 Hz, Ph), 131.6 (CHo, JPC
5.5 Hz, PCH2Ph), 133.6 (Cipso, NCH2Ph), 134.4 (CH, JPC
)
)
10.1 Hz, Ph), 135.0 (CHp, JPC ) 2.8 Hz, Ph), 176.3 (HNdC).
31P{1H} NMR in CDCl3, δ: 23.5.
1
cm-1: 3274 mw ν(N-H), 1661 s ν(CdN), 1433 s ν(CdC). H
NMR spectrum in CDCl3, δ: 0.94 (t, J ) 7.5 Hz, 3H, CH2Me),
2.14 (q, J ) 7.5 Hz, 2H, CH2Me), 3.96 (m, 4H, CH2C6H4Cl-p),
7.21-7.36 (m, 4H, aryl), 8.51 (s, br, 1H, NH). 13C{1H} NMR in
CDCl3, δ: 9.8 (CH3) and 25.6 (CH2)(Et), 61.0 (CH2, NCH2C6H4-
Cl-p), 128.8, 130.8, 131.2, 132.3, 132.4, and 134.3 (aryls), 173.3
(HNdC).
[Ph3PCH2Ph][PtCl3{NHdC(Et)ON(CH2C6H4Cl-p)2}] (8). Anal.
Calcd for C42H40N2Cl5OPPt: C, 50.85; H, 4.06; N, 2.82%. Found:
C, 50.83; H, 4.04; N, 2.78%. FAB+-MS, m/z: 353 [Mcation], 262
[Mcation - CH2Ph]. FAB- -MS, m/z: 602 [Manion], 533 [Manion
3Cl + H]. IR spectrum (selected bands), cm-1
3204 mw
-
:
ν(N-H), 1663 s ν(CdN), 1439 s ν(CdC), 1111 s ν(P-C), 750 m
δ(C-H). 1H NMR spectrum in CDCl3, δ: 0.85 (t, J ) 7.5 Hz, 3H,
CH2Me), 2.80 (q, J ) 7.5 Hz, 2H, CH2Me), 4.05 (s, 4H, CH2C6H4-
Addition of R2NOH to [Ph3PCH2Ph][PtCl3(EtCN)]. In a
typical experiment, I (0.10 g, 0.140 mmol) is suspended in
chloroform (10 mL) at 20-25 °C, the hydroxylamine (0.140 mmol)
is added, and the reaction mixture is left to stand on vigorous stirring
for 12 h at room temperature. The bright yellow-orange solution is
evaporated to dryness under a flow of N2 and the solid residue is
2
Cl-p), 5.00 (d, JPH ) 13.5 Hz, 2H, PCH2Ph), 7.07-7.82 and
(m, CH, aryl), 8.15 (s, br, 1H, NH). 13C{1H} NMR in CDCl3, δ:
1
11.5 (CH3) and 24.5 (CH2)(Et), 31.5 (CH2, JPC ) 47.7 Hz,
PCH2Ph), 62.0 (CH2, NCH2C6H4Cl-p), 117.3, 118.5, 127.3, 128.9,
Inorganic Chemistry, Vol. 44, No. 8, 2005 2951

Luzyanin et al.
129.5, 130.7, 130.9, 131.6, 132.1, 132.4, 134.8, 135.0 and 135.5
(aryls), 176.5 (HNdC). 31P{1H} NMR in CDCl3, δ: 28.1.
Addition of R2NOH to [PtCl4(EtCN)2]. In a typical experiment,
isomerically pure trans-IV27 (0.12 g, 0.266 mmol) [or a mixture
of cis/trans-IV which contains, by NMR, ca. 60% of the cis-
isomer27] is dissolved in chloroform (5 mL) at 20-25 °C, the
hydroxylamine (0.522 mmol) is added, and the reaction mixture is
left to stand for 15 min at room temperature. The bright yellow
solution is evaporated to dryness at room temperature under a flow
of N2 and the solid residue is washed with diethyl ether (five 3-mL
portions) to remove the excess of the hydroxylamine. Yields are
90-95%, based on Pt. In the cases of both trans-IV and a mixture
of cis/trans-IV, only the isomerically pure trans-[PtCl4{NHdC(Et)-
ONR2}2] was isolated.
trans-[PtCl4{NHdC(Et)ONMe2}2] (trans-9). Anal. Calcd for
C10H24N4Cl4O2Pt: C, 21.10; H, 4.25; N, 9.84%. Found: C, 21.02;
H, 4.10; N, 9.69%. FAB-MS, m/z: 533 [M - Cl]+, 498
[M - 2Cl]+. IR spectrum (selected bands), cm-1: 3225 mw
ν(N-H), 1664 s ν(CdN), 1438 s ν(CdC), 750 s δ(C-H). 1H NMR
spectrum in CDCl3, δ: 1.02 (t, J ) 7.5 Hz, 3H, CH2Me), 2.88
(s, 6H, NMe), 2.92 (q, J ) 7.5 Hz, 2H, CH2Me), 9.01 (s, br, 1H,
NH). 13C{1H} NMR spectrum in CDCl3, δ: 8.2 (CH3), 20.1 (CH2)-
(Et), 52.2 (Me, NMe), 174.5 (HNdC).
CH2Ph]. FAB--MS, m/z: 489 [Manion], 417 [Manion - 2Cl], 373
[PtCl5]. IR spectrum (selected bands), cm-1: 3225 mw ν(N-H),
1655 s ν(CdN), 1438 s ν(CdC), 1111 s ν(P-C), 750 s δ(C-H).
1H NMR spectrum in CDCl3, δ: 1.14 (t, J ) 7.5 Hz, 3H, CH2Me),
2.98 (qu, J ) 7.5 Hz, 2H, CH2Me), 3.09 (s, 3H,NMe), 4.91
2
(d, JPH ) 13.8 Hz, 2H, PCH2Ph), 6.97-7.29 and 7.53-7.74
(m, CH, Ph), 8.78 (s, br, 1H, NH). 13C{1H} NMR spectrum in
CDCl3, δ: 10.2 (CH3), 21.1(CH2)(Et), 30.8 (CH2, 1JPC ) 47.7 Hz,
PCH2Ph), 47.2 (Me, NMe), 116.6, 117.7, 126.7, 128.5, 128.8, 130.1,
130.2, 131.2, 134.1, and 135.0 (aryls), 176.5 (HNdC). 31P{1H}
NMR in CDCl3, δ: 23.2.
[Ph3PCH2Ph][PtCl5{NHdC(Et)ONEt2}] (14). Anal. Calcd for
C32H38N2Cl5OPPt: C, 44.18; H, 4.40; N, 3.22%. Found: C, 43.79;
H, 4.31; N, 3.24%. FAB+-MS, m/z: 353 [Mcation], 262 [Mcation
-
CH2Ph]. FAB--MS, m/z: 514 [Manion - H], 444 [Manion - 2Cl],
373 [PtCl5]. IR spectrum (selected bands), cm-1: 3220 m-w
ν(N-H), 1663 s ν(CdN), 1437 s ν(CdC), 1111 s ν(P-C), 748 m
δ(C-H). 1H NMR spectrum in CDCl3, δ: 1.14 (t, J ) 7.5 Hz, 6H,
NCH2Me), 1.24 (t, J ) 7.5 Hz, 3H, CH2Me), 2.96 (q, J ) 7.5 Hz,
4H, NCH2Me), 3.13 (q, J ) 7.5 Hz, 2H, CH2Me), 5.00 (d, 2JPH
)
13.5 Hz, 2H, PCH2Ph), 7.05-7.82 (m, CH, Ph), 9.15 (s, br, 1H,
NH). 13C{1H} NMR spectrum in CDCl3, δ: 10.9 (CH2Me), 11.7
1
(NCH2Me), 24.1 (CH2Me), 31.5 (CH2, JPC ) 47.6 Hz, PCH2Ph),
52.9 (NCH2Me), 116.8, 117.9, 128.4, 128.8, 130.4, 131.6, 134.4,
135.0 (Ph), 177.6 (HNdC). 31P{1H} NMR in CDCl3, δ: 28.4.
[Ph3PCH2Ph][PtCl5{NHdC(Et)ON(CH2Ph)2}] (15). Anal. Cal-
cd for C42H42N2Cl5OPPt: C, 50.74; H, 4.26; N, 2.82%. Found: C,
50.68; H, 4.22; N, 2.74%. FAB+-MS, m/z: 353 [Mcation], 262 [Mcation
- CH2Ph]. FAB--MS, m/z: 641 [Manion], 569 [Manion - 2Cl]. IR
trans-[PtCl4{NHdC(Et)ONEt2}2] (trans-10). Anal. Calcd for
C14H32N4Cl4O2Pt: C, 26.89; H, 5.16; N, 8.96%. Found: C, 26.44;
H, 5.01; N, 8.82%. FAB-MS, m/z: 624 [M]+, 554 [M - 2Cl]+. IR
spectrum (selected bands), cm-1: 3220 m-w ν(N-H), 1665 s
1
ν(CdN), 1438 m ν(CdC). H NMR spectrum in CDCl3, δ: 0.99
(t, J ) 7.5 Hz, 6H, NCH2Me), 1.20 (t, J ) 7.5 Hz, 3H, CH2Me),
2.88-3.02 (m, 4H, NCH2Me and 2H, CH2Me), 9.02 (s, br, 1H,
NH). 13C{1H} NMR in CDCl3, δ: 8.2 (CH3) and 22.4 (CH2)(Et),
11.6 (CH3) and 61.4 (CH2)(NEt), 174.2 (HNdC).
trans-[PtCl4{NHdC(Et)ON(CH2Ph)2}2] (trans-11). Anal. Calcd
for C34H40N4Cl4O2Pt: C, 46.75; H, 4.62; N, 6.41%. Found: C,
46.22; H, 4.60; N, 6.18%. FAB-MS, m/z: 873 [M + H]+, 767
spectrum (selected bands), cm-1
: 3222 mw ν(N-H), 1664 s
ν(CdN), 1437 s ν(CdC), 1111 s ν(P-C), 749 s δ(C-H). 1H NMR
spectrum in CDCl3, δ: 0.85 (t, J ) 7.5 Hz, 3H, CH2Me), 2.91
(q, J ) 7.5 Hz, 2H, CH2Me), 4.08 (s, 4H, NCH2Ph), 5.00
2
(d, JPH ) 13.5 Hz, 2H, PCH2Ph), 7.04 (m, 2H, ortho), 7.15
(m, 2H, meta) and 7.24 (m, 1H, para)(PCH2Ph), 7.30-7.42
(m, 10H, NCH2Ph), 7.58-7.70 (m, 12H, ortho + meta) and 7.78
(m, 3H, para)(Ph), 9.22 (s, br, 1H, NH). 13C{1H} NMR in CDCl3,
[M - 3Cl]+. IR spectrum (selected bands), cm-1
: 3237 s
1
ν(N-H), 1655 vs ν(CdN), 1435 m ν(CdC). H NMR spectrum
in CDCl3, δ: 0.90 (t, J ) 7.5 Hz, 3H, CH2Me), 2.78 (q, J )
7.5 Hz, 2H, CH2Me), 4.02-4.12 (m, 4H, CH2Ph), 7.25-7.42
(m, 5H, CH, Ph), 8.92 (s, br, 1H, NH).13C{1H} NMR in CDCl3, δ:
7.0 (CH3) and 23.8 (CH2)(Et), 58.4 (CH2, NCH2C6H5), 128.0-
134.0 (aryls), 173.0 (HNdC).
1
δ: 10.5 (CH3) and 24.0 (CH2)(Et), 31.5 (CH2, JPC ) 47.7 Hz,
PCH2Ph), 61.4 (CH2, NCH2Ph), 117.5 (Cipso, 1JPC ) 86.1 Hz, Ph),
126.9 (Cipso, 2JPC ) 8.9 Hz, PCH2Ph), 128.1 (CH, NCH2Ph), 128.5
(CHp, JPC ) 2.8 Hz, PCH2Ph), 128.8 (CH, NCH2Ph), 128.9 (CHm,
JPC ) 3.4 Hz, PCH2Ph), 129.8 (CH, NCH2Ph), 130.3 (CH, JPC
11.9 Hz, Ph), 131.6 (CHo, JPC ) 5.5 Hz, PCH2Ph), 133.6 (Cipso
NCH2Ph), 134.4 (CH, JPC ) 10.1 Hz, Ph), 135.0 (CHp, JPC
)
,
)
trans-[PtCl4{NHdC(Et)ON(CH2C6H4Cl-p)2}2] (trans-12). Anal.
Calcd for C34H36N4Cl8O2Pt: C, 40.38; H, 3.59; N, 5.54%. Found:
C, 40.11; H, 3.44; N, 5.02%. FAB-MS, m/z: 941 [M - 2Cl + H],
2.8 Hz, Ph), 176.3 (HNdC). 31P{1H} NMR in CDCl3, δ: 23.5.
[Ph3PCH2Ph][PtCl5{NHdC(Et)ON(CH2C6H4Cl-p)2}] (16). Anal.
Calcd for C42H40N2Cl7OPPt: C, 47.46; H, 3.79; N, 2.64%. Found:
C, 47.49; H, 3.75; N, 2.60%. FAB+-MS, m/z: 353 [Mcation], 262
[Mcation - CH2Ph]. FAB--MS, m/z: 636 [Manion - 2Cl], 616 [Manion
- 3Cl], 566 [Manion - 4Cl + H]. IR spectrum (selected bands),
cm-1: 3204 mw ν(N-H), 1663 s ν(CdN), 1439 s ν(CdC), 1111
906 [M - 3Cl + H]. IR spectrum (selected bands), cm-1
3230 mw ν(N-H), 1660 s ν(CdN), 1433 s ν(CdC). H NMR
spectrum in CDCl3, δ: 0.92 (t, J ) 7.5 Hz, 3H, CH2Me), 2.86
:
1
(quart,
J ) 7.5 Hz, 2H, CH2Me), 4.04-4.14 (m, 4H,
CH2C6H4Cl-p), 7.31-7.38 (m, 4H, aryl), 9.03 (s, br, 1H, NH).
13C{1H} NMR in CDCl3, δ: 6.2 (CH3) and 19.8 (CH2)(Et), 57.0
(CH2, NCH2C6H4Cl-p), 127.1-130.2 (aryls), 172.8 (HNdC).
Addition of R2NOH to [Ph3PCH2Ph][PtCl5(EtCN)]. In a
typical experiment, II (0.10 g, 0.128 mmol) is dissolved in
chloroform (10 mL) at 20-25 °C, the hydroxylamine (0.128 mmol)
is added, and the reaction mixture is left to stand for 3 h at room
temperature. The bright yellow solution is evaporated to dryness
under a flow of N2 and the solid residue is washed with diethyl
ether (five 3-mL portions) to remove the excess of the hydroxy-
lamine. Yields are 80-90%, based on Pt.
1
s ν(P-C), 750 m δ(C-H). H NMR spectrum in CDCl3, δ: 0.85
(t, J ) 7.5 Hz, 3H, CH2Me), 2.90 (q, J ) 7.5 Hz, 2H, CH2Me),
2
4.05 (s, 4H, CH2C6H4Cl-p), 5.00 (d, JPH ) 13.5 Hz, 2H,
PCH2Ph), 7.07-7.82 and (m, CH, aryl), 9.15 (s, br, 1H, NH).
13C{1H} NMR in CDCl3, δ: 11.5 (CH3) and 24.5 (CH2)(Et), 31.5
(CH2, 1JPC ) 47.7 Hz, PCH2Ph), 62.0 (CH2, NCH2C6H4Cl-p), 117.3,
118.5, 127.3, 128.9, 129.5, 130.7, 130.9, 131.6, 132.1, 132.4, 134.8,
135.0 and 135.5 (aryls), 176.5 (HNdC). 31P{1H} NMR in CDCl3,
δ: 28.1.
[Ph3PCH2Ph][PtCl5{NHdC(Et)ONMe2}] (13). Anal. Calcd for
X-ray Structure Determinations. The 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
C30H34N2Cl5OPPt: C, 42.80; H, 4.07; N, 3.33%. Found: C, 41.67;
H, 4.07; N, 3.17%. FAB+-MS, m/z: 353 [Mcation], 262 [Mcation
2952 Inorganic Chemistry, Vol. 44, No. 8, 2005
-

Platinum-Mediated Nitrile-Hydroxylamine Coupling
within the cold gas stream of the diffractometer. The Denzo-
Scalepack34 or EvalCCD35 programs packages were used for cell
refinements and data reduction. Structures were solved by direct
methods using the SHELXS or SIR-2002 program.36,37 The structure
trans-4 was solved as a racemic mixture (ratio ca. 0.4/0.6) in the
monoclinic space group P21. A multiscan absorption correction
based on equivalent reflections (XPREP in SHELXTL v. 6.14)38
was applied to data (Tmin/Tmax values were 0.1907/0.6272, 0.3219/
0.4584, 0.08068/0.13409, and 0.15477/0.21243 for cis-1, cis-2,
trans-4, and 15, respectively). The structures were refined with
SHELXL-9739 and WinGX graphical user interface.40 In cis-1,
cis-2, and trans-4, the NH hydrogens were located from the
difference Fourier map and refined isotropically (cis-1 and trans-
4) or were fixed (cis-2). All other hydrogens were placed in
idealized position and constrained to ride on their parent atom.
Crystallographic data are summarized in Table 1. Selected bond
lengths and angles are shown in Table 2 and in the caption of Figure
3.
Kinetic Measurements. The kinetics of reactions 1 and 2 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 -30 to 50 °C. The progress
of reactions was monitored by integrating the 1H NMR signals from
the coordinated EtCN of [Ph3PCH2Ph][PtCln(EtCN)] or signals of
the Et group from the imino ligand of [Ph3PCH2Ph][PtCln{NHd
C(Et)ON(CH2C6H4Cl-p)2}]. The pseudo-first-order conditions were
ensured by using at least 8-fold excess of (p-ClC6H4CH2)2NOH
(DAH) with respect to [Ph3PCH2Ph][PtCln(EtCN)]. The reactions
were initiated by mixing solutions of [Ph3PCH2Ph]-
[PtCln(EtCN)] and DAH in CDCl3 to give the total solution volume
0.5 mL. Commonly used concentrations of [Ph3PCH2Ph]-
[PtCln(EtCN)] and DAH were 1.35 × 10-3 M and (1.08-10.8) ×
10-2 M, respectively. The pseudo-first-order rate constants kobs were
calculated from the slope of linear plots ln(100/(100 - x)) versus
time where x (in %) 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 an Origin 6.1 package.
Acknowledgment. This work has been partially sup-
ported 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. expresses gratitude to FCT
and the POCTI program (FEDER funded), Portugal, for a
fellowship (grant SFRH/BD/10464/2002). 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 for a grant (03-03-32363), the POCTI program
(FEDER funded) (Cientista 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.H.
thanks the Academy of Finland for financial support. The
authors thank Dr. Maxim L. Kuznetsov for valuable discus-
sion, Dr. Nadezhda A. Bokach for experimental assistance,
Dr. Maria Caˆndida Vaz for the elemental analysis service,
and Mr. Indale´cio Marques for running of the FAB-MS
spectra.
(34) Otwinowski, Z.; Minor, W. Processing of X-ray Diffraction Data
Collected in Oscillation Mode. In Macromolecular Crystallography,
Part A; Carter, C. W., Jr., Sweet, R. M., Eds.; Methods in Enzymology,
Volume 276; Academic Press: New York, 1997; pp 307-326.
(35) Duisenberg, A. J. M.; Kroon-Batenburg, L. M. J.; Schreurs, A. M.
M. J. Appl. Cryst. 2003, 36, 220-229.
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