Platinum(IV)-mediated nitrile-sulfimide coupling: A route to heterodiazadienes

Article abstract of DOI:10.1021/ic025960w

Pt(IV)-mediated addition of the sulfimide Ph2S=NH and the mixed sulfide/sulfimides o- and p-{PhS(=NH)}(PhS)- C₆H₄ by the S=NH group to the metal-bound nitriles in the platinum(IV) complexes [PtCl₄(RCN)₂] proceeds smoothly at room temperature in CH₂Cl₂ and results in the formation of the heterodiazadiene compounds [PtCl₄{NH= C(R)N=SR′Ph}₂] (R′ = Ph, R = Me, Et, CH₂Ph, Ph; R′ = o- and p-(PhS)C₆H₄; R = Et). While trans-[PtCl₄-(RCN)₂] (R = Et, CH₂Ph, Ph) reacting with Ph₂S=NH leads exclusively to trans-[PtCl₄{NH=C(R)N=SPh₂}₂], cis/trans-[PtCl₄(MeCN)₂] leads to cis/trans mixtures of [PtCl₄{NH=C(Me)N=SPh₂}₂] and the latter have been separated by column chromatography. Theoretical calculations at both HF//HF and MP2//HF levels for the cis and trans isomers of [PtCl₄{NH=C(Me)N=SMe₂}₂] indicate a higher stability for the latter. Compounds trans-[PtCl₄- {E-NH=C(R)N=SPh₂}₂] (R = Me, Et) and cis-[PtCl₄{E-NH=C(Me)N=SPh₂}{Z-NH=C(Me) N=SPh₂}] have been characterized by X-ray crystallography, The complexes [PtCl₄{NH=C(R)N=SPh₂}₂] undergo hydrolysis when treated with HCI in nondried CH₂Cl₂ to achieve the amidines [PtCl₄{NH=C(NH₂)R}₂] (the compound with R = Et has been structurally characterized) and Ph₂SO. The heterodiazadiene ligands, formed upon Pt(IV)-mediated RCN/ sulfimide coupling, can be liberated from their platinum(IV) complexes [PtCl₄{NH=C(R)N=SR′Ph}₂] by reaction with Ph₂PCH₂CH₂PPh₂ (dppe) giving free NH=C(R)=SR′Ph and the dppe oxides, which constitutes a novel route for such rare types of heterodiazadienes whose number has also been extended. The hybrid sulfide/sulfimide species o- and p-{PhS(=NH)}(PhS)C₆H₄ also react with the Pt(II) nitrile complex [PtCl₂(MeCN)₂] but the coupling-in contrast to the Pt(IV) species - gives the chelates [PtCl₂{NH=C(Me)N=S(Ph)C₆H₄SPh}], The X-ray crystal structure of [PtCl₂{NH=C(Me)N=S(Ph)C₆H₄SPh-o}] reveals the bond parameters within the metallacycle and shows an unusual close interaction of the sulfide sulfur atom with the platinum.

Full text of DOI:10.1021/ic025960w

Inorg. Chem. 2003, 42, 301−311
Platinum(IV)-Mediated Nitrile−Sulfimide Coupling: A Route to
Heterodiazadienes
,†
Anastassiya V. Makarycheva-Mikhailova,† Nadezhda A. Bokach,† Vadim Yu. Kukushkin,*
Paul F. Kelly,* Liam M. Gilby,‡ Maxim L. Kuznetsov,§ Kathryn E. Holmes‡, Matti Haukka,|
Jonathan Parr,‡ Julia M. Stonehouse,‡ Mark R. J. Elsegood,‡ and Armando J. L. Pombeiro*
,‡
,§
Department of Chemistry, St. Petersburg State UniVersity, 198504 Stary Petergof, Russian
Federation, Department of Chemistry, Loughborough UniVersity, Loughborough LE11 3TU, U.K.,
Department of Chemistry, UniVersity of Joensuu, P.O. Box 111, FIN-80101, Joensuu, Finland, and
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, AV. RoVisco Pais,
1049-001 Lisbon, Portugal
Received August 20, 2002
Pt(IV)-mediated addition of the sulfimide Ph2SdNH and the mixed sulfide/sulfimides o- and p-{PhS(dNH)}(PhS)-
C H by the SdNH group to the metal-bound nitriles in the platinum(IV) complexes [PtCl4(RCN)2] proceeds smoothly
6
4
at room temperature in CH Cl2 and results in the formation of the heterodiazadiene compounds [PtCl4{NHd
2
C(R)NdSR′Ph}2] (R′ ) Ph, R ) Me, Et, CH Ph, Ph; R′ ) o- and p-(PhS)C H ; R ) Et). While trans-[PtCl4-
2
6 4
(RCN)2] (R ) Et, CH Ph, Ph) reacting with Ph2SdNH leads exclusively to trans-[PtCl4{NHdC(R)NdSPh2}2],
2
cis/trans-[PtCl4(MeCN)2] leads to cis/trans mixtures of [PtCl4{NHdC(Me)NdSPh2}2] and the latter have been
separated by column chromatography. Theoretical calculations at both HF//HF and MP2//HF levels for the cis and
trans isomers of [PtCl4{NHdC(Me)NdSMe2}2] indicate a higher stability for the latter. Compounds trans-[PtCl4-
{E-NHdC(R)NdSPh2}2] (R) Me, Et) and cis-[PtCl4{E-NHdC(Me)NdSPh2}{Z-NHdC(Me)NdSPh2}] have been
characterized by X-ray crystallography. The complexes [PtCl4{NHdC(R)NdSPh }2] undergo hydrolysis when treated
2
with HCl in nondried CH Cl2 to achieve the amidines [PtCl4{NHdC(NH )R}2] (the compound with R ) Et has
2
2
been structurally characterized) and Ph2SO. The heterodiazadiene ligands, formed upon Pt(IV)-mediated RCN/
sulfimide coupling, can be liberated from their platinum(IV) complexes [PtCl4{NHdC(R)NdSR′Ph}2] by reaction
with Ph2PCH CH PPh2 (dppe) giving free NHdC(R)dSR′Ph and the dppe oxides, which constitutes a novel route
2
2
for such rare types of heterodiazadienes whose number has also been extended. The hybrid sulfide/sulfimide
species o- and p-{PhS(dNH)}(PhS)C H also react with the Pt(II) nitrile complex [PtCl2(MeCN)2] but the couplings
6
4
in contrast to the Pt(IV) speciessgives the chelates [PtCl2{NHdC(Me)NdS(Ph)C H SPh}]. The X-ray crystal
6
4
structure of [PtCl2{NHdC(Me)NdS(Ph)C H SPh-o}] reveals the bond parameters within the metallacycle and shows
6
4
an unusual close interaction of the sulfide sulfur atom with the platinum.
Introduction
the possibilities (i) to use nitriles as versatile synthons for
the preparation of new compounds, often unreachable in pure
organic synthesis, via C-O, C-N, C-C, C-P, and C-S
Addition to metal-activated RCtN species is one of the
frontier areas of current research on organonitriles, and this
topic has been the subject of comprehensive reviews1
including a recent survey by two of us.2 In general, the
interest in conversions of nitriles at metal centers stems from
(1) (a) Eglin, J. L. Comments Inorg. Chem. 2002, 23, 23. (b) Murahashi,
S.-I.; Takaya, H. Acc. Chem. Res. 2000, 33, 225. (c) da Rocha, Z. N.;
Chiericato, G., Jr.; Tfouni, E. AdV. Chem. Ser. 1997, 253, 297. (d)
Michelin, R. A.; Mozzon, M.; Bertani, R. Coord. Chem. ReV. 1996,
147, 299. (e) Murahashi, S.-I.; Naota, T. Bull. Chem. Soc. Jpn. 1996,
69, 1805. (f) Murahashi, S.-I.; Naota, T. Chemtracts: Org. Chem.
1994, 7, 281. (g) Corain, B.; Basato, M.; Veronese, A. C. J. Mol.
Catal. 1993, 81, 133.
(2) (a) Kukushkin, V. Yu.; Pombeiro, A. J. L. Chem. ReV. 2002, 102,
1771. (b) Pombeiro, A. J. L.; Kukushkin, V. Yu. In ComprehensiVe
Coordination Chemistry, 2nd ed.; Elsevier: New York, 2003; Vol. 1,
in press.
* To whom correspondence should be addressed. E-mail: kukushkin@
VK2100.spb.edu (V.Yu.K.); P.F.Kelly@lboro.ac.uk (P.F.K.); pombeiro@
ist.utl.pt (A.J.L.P.).
† St. Petersburg State University.
‡ Loughborough University.
§ Instituto Superior Te´cnico.
| University of Joensuu.
10.1021/ic025960w CCC: $25.00 © 2003 American Chemical Society
Published on Web 12/28/2002
Inorganic Chemistry, Vol. 42, No. 2, 2003 301

Makarycheva-Mikhailova et al.
bond making, (ii) to provide environmentally friendly metal-
catalyzed hydrolytic transformation of RCN species to
amides, e.g., of industrial and pharmacological significance,
and (iii) to synthesize, via nucleophilic addition, diverse
imino complexes, e.g., exhibiting unusual antitumor proper-
ties. The analysis of experimental material collected to date2
shows that the largest fraction of research is devoted to the
creation of the C-N bond by the addition of ammonia,
primary and secondary amines, hydrazines, and hydroxyl-
amines as well as by coupling of some nitrogen heterocycles
with ligated RCN species. New reactions leading to the C-N
bond that have emerged in the past months (and were not
covered in the review2) include the Ni(II)-templated forma-
tion of imidoylamidines,3 molybdenum-4a and platinum-
mediated4b amine-nitrile coupling, and the formation of
amidines from conversions of alkyl nitriles at a Pt(II) center;5
the latter is relevant to the formation of amidines at a Co(II)
center observed previously by us.6
Figure 1.
We report herein on the facile and selective Pt(IV)-
mediated addition of sulfimides and mixed sulfide/sulfimides
by the SdNH group to metal-bound nitriles to produce
ligated heterodiazadienes which can be liberated by the
reaction with 1,2-bis(diphenylphosphino)ethane (dppe) and
isolated as solids.
Despite the large number of examples of the metal-
mediated RCN-amine integration, only a few works deal
with nitrile-imine (or heteroimine) coupling. Thus, one part
of the current team has pioneered the addition of the
sulfimide Ph2SdNH to (nitrile)PtII complexes,7,8 while the
other part of the team observed the addition of Ph2CdNH
to (nitrile)PtIV complexes.9 Such reactions generate chelated7,8
or monodentate8,9 diazadiene species of the type HNd
C(R)NdEPh2 (E ) S, C). We have now endeavored to
extend our investigations by combining the experience of
both groups to assess the reactivity of sulfimides toward the
organonitrile platinum(IV) complexes [PtCl4(RCN)2]. Our
interest in these processes was at least 3-fold: (i) to verify
the effect of the oxidation state of the Pt center on the
addition of Ph2SdNH to coordinated nitriles; (ii) to liberate
HNdC(R)NdSPh2 species and to develop a route for
preparation of this little explored type of heterodiazadiene;
(iii) to assess the effect of derivatization upon the reactivity
of the sulfimide (toward both Pt(II) and Pt(IV)) by observing
the analogous reactions of mixed sulfide/sulfimides. The
presence of the thioether unit in the latter species provides
an extra potential coordinating atom for the new ligands
formed in such reactions. Previous work7 has demonstrated
that the addition reaction with nitriles tends to activate the
sulfimide sulfur atom toward metal coordination; thus
successful reactions involving the mixed ligands would
provide routes to ligands that would be potentially tridentate
in nature.
Experimental Section
Instrumentation and Materials.
Instrumentation has been previously described.9 Sulfimides IA10
(see Figure 1) and IB11 were synthesized in accord with the
published methods, while IC was prepared in an analogous manner
to IB using p-(PhS)2C6H4 as the starting sulfide. Solvents were
obtained from commercial sources and used as received. Ph3-
PdCHCO2Me was purchased from Lancaster. In the nitrile
compounds [PtCl4(RCN)2] (R ) Me, Et, CH2Ph, Ph), the first
complex was prepared by chlorination of a mixture of the cis- and
trans-[PtCl2(MeCN)2] isomers (ca. 5:1 for R ) Me12) giving a
mixture of cis/trans-[PtCl4(MeCN)2] with almost the same isomeric
ratio. trans-[PtCl4(RCN)2] (R ) Et, CH2Ph) were obtained by
chlorination of the pure trans-[PtCl2(RCN)2] isomers,13,14 while the
latter complex, i.e. trans-[PtCl4(PhCN)2], was obtained by heating
of cis/trans-[PtCl2(MeCN)2] in neat PhCN; isolation of trans-[PtCl2-
(PhCN)2]15 was followed by its oxidation with Cl2 in accord with
the published procedure.
Synthetic Work.
Addition of Sulfimides to [PtCl4(RCN)2] Complexes. Ph2Sd
NH‚H2O (IA) (0.1 mmol) is added to a suspension of [PtCl4(RCN)2]
(R ) Me, Et, CH2Ph, Ph) (0.05 mmol) in CH2Cl2 (2 mL). The
reaction mixture becomes orange-yellow in 1-2 min, whereupon
the solvent is evaporated to dryness and the orange residue is
(3) Kryatov, S. V.; Nazarenko, A. Y.; Smith, M. B.; Rybak-Akimova, E.
V. Chem. Commun. 2001, 1174.
(10) Kelly, P. F.; Man, S.-M.; Slawin, A. M. Z.; Waring, K. W. Polyhedron
1999, 18, 3173.
(11) Elsegood, M. R. J.; Holmes, K. E.; Kelly, P. F.; Parr, J.; Stonehouse,
J. M. New J. Chem. 2002, 26, 202.
(12) Fanizzi, F. P.; Intini, F. P.; Maresca, L.; Natile, G. J. Chem. Soc.,
Dalton Trans. 1990, 199.
(13) (a) Svensson, P.; Lo¨vqvist, K.; Kukushkin, V. Yu.; Oskarsson, Å. Acta
Chem. Scand. 1995, 49, 72. (b) Kukushkin, V. Yu.; Oskarsson, Å.;
Elding, L. I. Inorg. Synth. 1997, 31, 279.
(14) Kukushkin, V. Yu.; Tkachuk, V. M.; Vorobiov-Desiatovsky, N. V.
Inorg. Synth. 1998, 32, 144.
(15) (a) Uchiyama, T.; Nakamura, Y.; Miwa, T.; Kawaguchi, S.; Okeya,
S. Chem. Lett. 1980, 337. (b) Uchiyama, T.; Toshiyasu, Y.; Nakamura,
Y.; Miwa, T.; Kawaguchi, S. Bull. Chem. Soc. Jpn. 1981, 54, 181.
(4) (a) Du., S.; Kautz, J. A.; McGrath, T. D.; Stone, F. G. A. J. Chem.
Soc., Dalton Trans. 2002, 1553. (b) Belluco, U.; Benetollo, F.; Bertani,
R.; Bombieri, G.; Michelin, R. A.; Mozzon, M.; Tonon, O.; Pombeiro,
A. J. L.; Guedes da Silva, F. C. Inorg. Chim. Acta 2002, 334, 437.
(5) Longato, B.; Bandoli, G.; Mucci, A.; Schenetti, L. Eur. J. Inorg. Chem.
2001, 3021.
(6) 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.
(7) Kelly, P. F.; Slawin, A. M. Z. Chem. Commun. 1999, 1081.
(8) Kelly, P. F.; Slawin, A. M. Z. Eur. J. Inorg. Chem. 2001, 263.
(9) Garnovskii, D. A.; Kukushkin, V. Yu.; Haukka, M.; Wagner, G.;
Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans. 2001, 560.
302 Inorganic Chemistry, Vol. 42, No. 2, 2003

Platinum(IV)-Mediated Nitrile-Sulfimide Coupling
washed by Et2O (two 3-mL portions) and dried in air at 20-25
°C. Yield: 75-90%. Reaction with IB or IC is performed similarly.
Complexes 1 and 2 were prepared from the mixture of the cis-
and trans-[PtCl2(MeCN)2] isomers and IA, and after the reaction,
1 and 2 were separated by column chromatography on silica gel
(Chemapol Silicagel L 40/100; eluent is CHCl3). The ratio between
trans-1 and cis-2 approximately corresponds to the ratio between
the trans and cis isomers in the starting mixture of trans- and cis-
[PtCl4(MeCN)2].
[M - H]+, 901 [M - H - 2Cl]+, 867 [M - 3Cl]+, 830 [M -
4Cl - H]+. Mp: 138 °C. TLC on Merck 60 F254 SiO2 plates:
Rf ) 0.59 (eluent Et2O-CH2Cl2, 1:40). IR spectrum in KBr, selected
bands, cm-1: 3437 s-m ν(O-H), 3325 m-w ν(N-H), 3055 w and
1
2923 w ν(C-H), 1524 s ν(CdN), 1440 m ν(CdC Ar). H NMR
spectrum in CDCl3, δ: 7.3 and 7.1 (m, 15H, CH2Ph and dSPh2),
6.80 (s, br, 1H, NH), 4.63 (s, br, 2H, CH2Ph). 13C{1H} NMR
spectrum in CDCl3, δ: 176.93 (CdN), 134.19 (Cipso), 132.15 (p-
Ph), 129.72 and 127.00 (m- and o-Ph), 130.08, 128.08 and 127.90
(o-, m- and p-CH2Ph), CH2Ph not detected. 195Pt{1H} NMR
spectrum in CDCl3, δ: 94.2 (370 Hz).
trans-[PtCl4{NHdC(Ph)NdSPh2}2] (5). The complex was
prepared from trans-[PtCl4(PhCN)2] and IA. Anal. Calcd for
C38H32N4Cl4PtS2: C, 48.26; H, 3.41; N, 5.92; S, 6.78. Found: C,
48.02; H, 3.50; N, 5.45; S, 6.21. FAB+-MS, m/z: 839 [M - 3Cl]+,
802 [M - 4Cl - H]+. Mp: 163 °C. TLC on Merck 60 F254 SiO2
plates: Rf ) 0.54 (eluent Et2O-CH2Cl2, 1:40). IR spectrum in KBr,
selected bands, cm-1: 3377 m-w ν(N-H), 3053 w and 2923 w
ν(C-H), 1524 s ν(CdN), 1443 m ν(CdC Ar). 1H NMR spectrum
in CDCl3, δ: 8.0, 7.8 and 7.4 (m, 15H, Ph), 6.11 (s, br, 1H, NH).
13C{1H} NMR spectrum in CDCl3, δ: 133.12 (p-PhS), 132.05 (p-
Ph), 130.32 and 128.68 (o- and m-Ph), 129.85 and 127.44 (o- and
m-PhS), Cipso and CdN not detected. 195Pt{1H} NMR spectrum in
CDCl3, δ: 92.0 (780 Hz).
trans-[PtCl4{NHdC(Me)NdSPh2}2] (1). Anal. Calcd for
C28H28N4Cl4PtS2: C, 40.93; H, 3.44; N, 6.82; S, 7.81. Found: C,
40.50; H, 3.35; N, 6.12; S, 7.75. FAB+-MS, m/z: 843 [M + Na]+,
823 [M + H]+, 785 [M - Cl]+, 715 [M - 3Cl]+. Mp: 137 °C
(dec). TLC on Merck 60 F254 SiO2 plates: Rf ) 0.46 (eluent Et2O-
CH2Cl2, 1:20). IR spectrum in KBr, selected bands, cm-1: 3326
m ν(N-H), 3052 w and 2920 w ν(C-H), 1539 s ν(CdN), 1437 m
1
ν(CdC Ar). H NMR spectrum in CDCl3, δ: 7.67 and 7.52 (m,
Ph, 10H), 6.53 (s, br, NH, 1H), 2.75 (s, br, Me, 3H). 13C{1H} NMR
spectrum in CDCl3, δ: 176.37 (CdN), 135.96 (Cipso), 132.61 (p-
Ph), 130.12 and 127.34 (m-Ph and o-Ph), 21.85 (Me). 195Pt{1H}
NMR spectrum in CDCl3, δ: 110.0 (640 Hz). Crystals for X-ray
study were obtained by slow evaporation of a CDCl3 solution.
cis-[PtCl4{NHdC(Me)NdSPh2}2] (2). Anal. Calcd for C28H28N4-
Cl4PtS2‚H2O: C, 40.06; H, 3.60; N, 6.67; S, 7.64. Found: C, 40.35;
H, 3.33; N, 6.10; S, 7.65. FAB+-MS, m/z: 843 [M + Na]+, 823
[M + H]+, 785 [M - Cl]+, 715 [M - 3Cl]+. Mp: 151 °C (dec).
TLC on Merck 60 F254 SiO2 plates: Rf ) 0.34 (eluent Et2O-CH2-
Cl2, 1:5). IR spectrum in KBr, selected bands, cm-1: 3425 s-m
ν(O-H), 3331 m ν(N-H), 3055 w and 2923 w ν(C-H), 1534 s
trans-[PtCl4{NHdC(Et)NdS(Ph)(o-C6H4SPh)}2] (6). The com-
plex was prepared from trans-[PtCl4(EtCN)2] and IB. Anal. Calcd
for C42H40N4Cl4PtS4: C, 47.32; H, 3.78; N, 5.26; S, 12.03. Found:
C, 47.75; H, 3.72; N, 5.18; S, 12.21. FAB+-MS, m/z: 994 [M -
2Cl]+, 958 [M - 3Cl - H]+. Mp: 197 °C. TLC on Merck 60 F254
SiO2 plates: Rf ) 0.61 (eluent Et2O-CH2Cl2, 1:40). IR spectrum
in KBr, selected bands, cm-1: 3323 m-w ν(N-H), 3055 w and
1
ν(CdN), 1440 m ν(CdC Ar). H NMR spectrum in CDCl3, δ:
two sets of signals from E and Z isomers of the ligand, 7.9-7.3
(m, 10H both, Ph), 7.11 and 6.11 (two s, br, 2H both, NH), 2.36
and 1.96 (two s, br, 3H both, Me). 13C{1H} NMR spectrum in
CDCl3, δ: 176.37 (CdN), 135.96 and 136.41 (Cipso), 132.61 (p-
Ph), 130.12 and 130.36, 127.34 and 127.79 (m-Ph and o-Ph), 21.85
and 24.14 (Me). 195Pt{1H} NMR spectrum in CDCl3, δ: 187.9 (740
Hz). Slow evaporation of a CH2Cl2-Et2O solution of 2 gave crystals
(used for X-ray study) of the bis-solvate cis-[PtCl4{NHdC(Me)Nd
SPh2}2]‚2CH2Cl2. Anal. Calcd for C28H28N4Cl4PtS2‚2CH2Cl2: C,
36.34; H, 3.25; N, 5.65; S, 6.47. Found: C, 36.02; H, 3.39; N,
5.72; S, 6.35. Note that only one solvent molecule appears in the
X-ray structure due to disorder of the second molecule.
trans-[PtCl4{NHdC(Et)NdSPh2}2]‚2H2O (3). The complex
was prepared from trans-[PtCl4(EtCN)2] and IA. Anal. Calcd for
C30H36N4Cl4O2PtS2: C, 40.68; H, 4.10; N, 6.33; S, 7.24. Found:
C, 41.07; H, 3.25; N, 6.28; S, 7.21. FAB+-MS, m/z: 743 [M -
3Cl]. Mp: 185 °C. TLC on Merck 60 F254 SiO2 plates: Rf ) 0.70
(eluent Et2O-CH2Cl2, 1:20). IR spectrum in KBr, selected bands,
cm-1: 3431 s-m ν(O-H), 3321 m-w ν(N-H), 3054 w and 2971
w ν(C-H), 1522 s ν(CdN), 1440 m ν(CdC Ar). 1H NMR
spectrum in CDCl3, δ: 7.73 and 7.50 (m, br, 10H, Ph), 6.24 (s, br,
1H, NH), 3.13 (s, br, 2H, CH2 from Et), 1.27 (t, br, 3H, CH3 from
Et). 13C{1H} NMR spectrum in CDCl3, δ: 179.99 (CdN), 135.72
(Cipso), 132.47(p-Ph), 130.01 and 127.28 (m-Ph and o-Ph), 30.04
(CH2 from Et), 12.95 (CH3 from Et). 195Pt{1H} NMR spectrum in
CDCl3, δ: 134.7 (400 Hz). Crystals for X-ray study were obtained
directly from the reaction mixture by slow, partial evaporation of
the solvent. The X-ray structure determination does not allow one
to locate the water of crystallization.
1
2930 w ν(C-H), 1516 s ν(CdN), 1440 m ν(CdC Ar). H NMR
spectrum in CDCl3, δ: two isomers in ca. 2:3 ratio, 8.1-7.2 (m,
Ph, both isomers), 6.36 (s, br, NH, major), 5.95 (s, br, NH, minor),
3.12 (s, br, CH2 from Et, major), 2.56 (s, br, CH2 from Et, minor),
1.21 (t, br, CH3 from Et), 1.18 (s, br, CH3 from Et, minor). 13C-
{1H} NMR spectrum in CDCl3, δ: 134.1, 132.8, 132.2, 131.0,
129.8, 129.7, 128.1, and 127.9 (o-, m- and p-Ph, C6H4), 29.05 (CH2
from Et), 12.85 (CH3 from Et). 195Pt{1H} NMR spectrum in CDCl3,
δ: two isomers in ca. 2:3 ratio, 140.7 (major, 320 Hz) and 102.0
(minor, 360 Hz).
trans-[PtCl4{NHdC(Et)NdS(Ph)(p-C6H4SPh)}2]‚3H2O (7).
The complex was prepared from trans-[PtCl4(EtCN)2] and IC. Anal.
Calcd for C42H46N4Cl4O3PtS4: C, 45.04; H, 4.14; N, 5.00; S, 11.45.
Found: C, 44.73; H, 3.66; N, 5.11; S, 11.34. FAB+-MS, m/z: 1067
[M + H]+, 1030 [M + H - Cl]+, 994 [M - 2Cl]+, 959 [M -
3Cl]+, 923 [M - 4Cl - H]+. Mp: 118 °C. TLC on Merck 60 F254
SiO2 plates: Rf ) 0.70 (eluent Et2O-CH2Cl2, 1:80). IR spectrum
in KBr, selected bands, cm-1: 3435 s-m ν(O-H), 3321 w ν(N-
H), 3052 w and 2968 w ν(C-H), 1523 s ν(CdN), 1439 m ν(CdC
Ar). 1H NMR spectrum in CDCl3, δ: 7.5-7.2 (m, 14H, Ph), 6.18
(s, br, 1H, NH), 3.11 (s, br, 2H, CH2 from Et), 1.25 (t, br, 3H, CH3
from Et). 13C{1H} NMR spectrum in CDCl3, δ: 179.65 (CdN),
134.23, 132.46, 131.36, 131.04, 130.05, 129.79, 129.15, 128.35,
127.90, and 127.17 (o-, m- and p-Ph, C6H4), 28.88 (CH2 from Et),
12.67 (CH3 from Et). 195Pt{1H} NMR spectrum in CDCl3, δ: 133
(567 Hz).
Addition of IB to the Nitrile in [PtCl2(MeCN)2]. A solution
of [PtCl2(MeCN)2] (0.109 g, 0.313 mmol) in MeCN (10 mL) is
treated dropwise, with stirring, with a solution of IB (0.097 g, 0.313
mmol) in an equal volume of the same solvent. After being stirred
at 50 °C for 4 h, the mixture is reduced to dryness in vacuo and
quickly washed with ice cold CH2Cl2 (10 mL). The resulting solid
trans-[PtCl4{NHdC(CH2Ph)NdSPh2}2]‚2H2O (4). The com-
plex was prepared from trans-[PtCl4(PhCH2CN)2] and IA. Anal.
Calcd for C40H40N4Cl4O2PtS2: C, 47.58; H, 3.99; N, 5.55; S, 6.35.
Found: C, 47.14; H, 3.57; N, 5.32; S, 6.70. FAB+-MS, m/z: 973
Inorganic Chemistry, Vol. 42, No. 2, 2003 303

Makarycheva-Mikhailova et al.
is then dissolved in CH2Cl2 (20 mL) at ambient temperature through
vigorous stirring and gentle heating and then crystallized by slow
diffusion of Et2O vapor into this solution. A further small crop of
crystals is obtained by Et2O vapor diffusion into the initial CH2Cl2
washings; these can be separated from the other material present
in this solution, which precipitates as an amorphous powder.
Combined yield of crystalline material: 98 mg (51%).
825 [M - 3Cl]+, 788 [M - 4Cl - H]+. Mp: 133 (dec) °C. IR
spectrum in KBr, selected bands, cm-1: 3458 s-m ν(O-H), 3330
m ν(N-H), 3059 w and 2928 w ν(C-H), 1666 and 1539 s ν(Cd
N), 1438 m ν(CdC Ar). The solubility of this compound in CDCl3
or acetone-d6 is insufficient to measure even the 1H NMR spectrum.
cis-[PtCl4{NHdC(NH2)Me}2] (11). This complex was obtained
by starting from 2. Anal. Calcd for C4H12N4Cl4Pt: C, 10.60; H,
2.67; N, 12.37. Found: C, 10.89; H, 2.74; N, 12.19. FAB+-MS,
m/z: 382 [M - 2Cl]+, 312 [M - 4Cl]+. Mp: 185 (dec) °C. IR
spectrum in KBr, selected bands, cm-1: 3341 m ν(N-H), 3220 w
[PtCl2{NHdC(Me)NdS(Ph)C6H4SPh-o}] (8). Anal. Calcd for
C20H18N2Cl2PtS2: C, 39.0; H, 2.9; N, 4.5. Found: C, 38.7; H, 2.8;
N, 4.3. FAB+-MS, m/z: 616 [M]+, 581 [M - Cl]+. Mp: 215 °C.
TLC on Merck 60 F254 SiO2 plates: Rf ) 0.29 (eluent hexane-
Et2O, 1:8). IR spectrum in KBr, selected bands, cm-1: 3343 m
1
and 3187 w ν(C-H), 1666 s ν(CdN), 1437 m ν(CdC Ar). H
NMR spectrum in acetone-d6, δ: 8.12, 7.75, 7.52 (s, br, 1H each,
NH and NH2), 2.37 (s, 3H).
1
ν(N-H), 1523 m ν(CdN), 801 m ν(SdN). H NMR spectrum in
CDCl3, δ: 8.24 (2H, dd, Ph C-H), 7.75-7.26 (12H, m, Ph C-H),
2.28 (3H, s, br, CH3). 13C{1H} NMR spectrum in CDCl3, δ: 182.3
(N-CdN), 133.4, 133.2, 133.0, 132.7, 132.0, 131.8, 131.4, 131.2,
129.7, 128.9, 128.8, 128.6, 128.1, 127.7, 127.5, 126.9, and 125.7
(Ph C-H), 18.1 (CH3). 195Pt NMR spectrum in CDCl3, δ: -3087
(346 Hz).
Addition of IC to the Nitrile in [PtCl2(MeCN)2]. A solution
of [PtCl2(MeCN)2] (0.107 g, 0.307 mmol) in MeCN (10 mL) is
treated dropwise, with stirring, with a solution of IC (0.095 g, 0.307
mmol) in an equal volume of the same solvent. After being stirred
at 50 °C for 4 h, the mixture is reduced to dryness in vacuo,
dissolved in CH2Cl2 (20 mL), and loaded onto a silica column.
Elution with hexane-Et2O (1:8) allows isolation of a yellow band
(Rf ) 0.2) containing the product. Yield: 46 mg (24%) after column
chromatography.
[PtCl2{NHdC(Me)NdS(Ph)C6H4SPh-p}] (9). Anal. Calcd for
C20H18N2Cl2PtS2: C, 39.0; H, 2.9; N, 4.5. Found: C, 38.8; H, 3.5;
N, 3.7. FAB+-MS, m/z: 581 [M - Cl]+. Mp: 120 °C. TLC on
Merck 60 F254 SiO2 plates: Rf ) 0.20 (eluent hexane-Et2O, 1:8).
IR spectrum in KBr, selected bands, cm-1: 3290 m ν(N-H), 1528
m ν(CdN), 805 m ν(SdN). 1H NMR spectrum in CDCl3, δ: 8.02
(2H, d, Ph C-H), 7.83 (2H, d, Ph C-H), 7.55-7.37 (8H, m, Ph
C-H), 7.13 (2H, d, Ph C-H), 2.32 (3H, s, CH3). 13C{1H} NMR
spectrum in CDCl3, δ: 182.6 (N-CdN), 134.3, 134.1, 133.2, 132.2,
130.4, 130.1, 129.6, 129.1, 129.0, 128.9, 128.6, 128.3, 127.4, 127.0,
126.4, 126.1, and 122.4 (Ph C-H), 18.0 (CH3). 195Pt NMR spectrum
in CDCl3, δ: -3167 (318 Hz).
trans-[PtCl4{NHdC(NH2)Et}2] (12). This complex was ob-
tained by starting from 3. Anal. Calcd for C6H16N4Cl4Pt: C, 14.98;
H, 3.35; N, 11.65. Found: C, 14.38; H, 3.35; N, 11.67. FAB+-
MS, m/z: 410 [M - 2Cl]+, 338 [M - 4Cl - H]+. Mp: 137 °C
(dec). IR spectrum in KBr, selected bands, cm-1: 3357 and 3321
w ν(N-H), 2989 w and 2938 w ν(C-H), 1655 s ν(CdN). 1H NMR
spectrum in DMSO-d6, δ: 8.45, 7.57, 7.17 (s, br, 1H each, NH
and NH2), 1.64 (t, 3H, CH3 from Et), CH2 from Et was not detected
due to overlap with the solvent signal. Crystals for the X-ray study
were obtained directly from the reaction mixture.
[PtCl4{NHdC(NH2)CH2Ph}2] (13). This complex was obtained
by starting from 4. Anal. Calcd for C16H20N4Cl4Pt: C, 31.75; H,
3.33; N, 9.26. Found: C, 31.54; H, 3.48; N, 9.13. FAB+-MS, m/z:
628 [M + Na]+, 534 [M - 2Cl]+. Mp: 192 °C (dec). IR spectrum
in KBr, selected bands, cm-1: 3455 s-m ν(O-H), 3333 and 3341
w ν(N-H), 2925 w ν(C-H), 1657 s ν(CdN), 1408 m ν(CdC Ar).
1H NMR spectrum in DMSO-d6, δ: 8.02, 6.99, 6.89 (s, br, 1H
each, NH and NH2), 7.39-7.24 (m, 5H, Ph), 3.84 (s, br, 2H, CH2-
Ph).
[PtCl4{NHdC(NH2)Ph}2] (14). This complex was obtained by
starting from 5. Anal. Calcd for C14H16N4Cl4Pt‚0.5H2O: C, 28.68;
H, 2.92; N, 9.56. Found: C, 28.64; H, 2.92; N, 9.27. FAB+-MS,
m/z: 506 [M - 2Cl]+, 434 [M - 4Cl - H]+. Mp: 214 °C (dec).
IR spectrum in KBr, selected bands, cm-1: 3445 s-m ν(O-H),
3348 and 3387 w ν(N-H), 1647 s ν(CdN), 1434 m ν(CdC Ar).
1H NMR spectrum in DMSO-d6, δ: 8.70, 7.34 (s, br, 1H each,
2
NH2), 6.54 (s + d, br, JPtH 23.4 Hz, 1H, dNH-Pt), 7.65-7.55
(m, 5H, Ph).
HCl-Promoted Hydrolysis of [PtCl4{NHdC(R)NdSPh2}2]
(R ) Me, Et, CH2Ph, Ph). Dry HCl is passed through a solution
of [PtCl4{NHdC(R)NdSPh2}2] (0.02 mmol) in dichloromethane
(2 mL) placed in an open beaker at 20-25 °C for 10-15 min,
whereupon the beaker is kept in a desiccator with a small amount
of concentrated aqueous HCl on the bottom. The precipitate formed
is filtered off, washed with three 3-mL portions of CH2Cl2, and
dried in air at room temperature. In the case of R ) Me the
precipitate (yield is 40%) is released from the reaction mixture after
2.5 h and the filtrate contains a number of yet unidentified species.
In the other cases the precipitates (crystals in the case of R ) Et)
formed after ca. 2 h (yields are 60-70%). All thus prepared
complexes exhibit poor solubility in the most common organic
solvents, and we were unable to measure their 13C{1H} and 195Pt
NMR spectra even at high accumulation time.
Reduction of trans-[PtCl4{NHdC(R)NdSPh2}2] (R ) Me,
Et). The ylide Ph3PdCHCO2Me (0.07 mmol) is added to a solution
of trans-[PtCl4{NHdC(R)NdSPh2}2] (1 or 3) (0.05 mmol) in
CH2Cl2 (2 mL). The reaction mixture is left to stand at 45 °C for
24-36 h. The product is separated by column chromatography on
SiO2 (Merck silica gel, grade 60, 70-230 mesh, eluent CH2Cl2-
Et2O, 10:1).
[PtCl2{NHdC(Me)NdSPh2}] (15). This product was obtained
by the reduction of 1. Anal. Calcd for C14H14N2Cl2PtS: C, 33.08;
H, 2.78; N, 5.51; S, 6.31. Found: C, 33.52; H, 2.89; N, 5.34; S,
6.05. FAB+-MS, m/z: 471 [M - Cl]+. Mp: 222 °C (dec). TLC on
Merck 60 F254 SiO2 plates: Rf ) 0.58 (eluent Et2O-CH2Cl2, 1:8).
IR spectrum in KBr, selected bands, cm-1: 3304 m ν(N-H), 3061
1
w and 2924 w ν(C-H), 1530 s ν(CdN), 1446 m ν(CdC Ar). H
The filtrate is evaporated at room temperature to give an oily
residue. IR, FAB-MS, EI-MS, and TLC analyses of the latter
showed the presence of Ph2SdO and chloro- and dichlorodiphenyl
sulfides in the mixture.
trans-[PtCl4{NHdC(Me)NdSPh2}2]‚(HCl)2‚2H2O (10). This
complex was obtained by starting from 1. Anal. Calcd for C28H34N4-
Cl6O2PtS2: C, 36.15; H, 3.66; N, 6.02. Found: C, 35.96; H, 3.83;
N, 6.14. FAB+-MS, m/z: 919 [M - Cl + Na]+, 860 [M - 2Cl]+,
NMR spectrum in CDCl3, δ: 8.09 and 7.60 (m, 10H, Ph), 6.51
(s + d, JPtH 55.0 Hz, br, 1H, NH), 2.40 (s, 3H, Me). 13C{1H} NMR
spectrum in CDCl3, δ: 135.34 (Cipso), 134.21 (p-Ph), 130.07 and
128.14 (o- and m-Ph), 19.08 (Me). 195Pt{1H} NMR spectrum in
CDCl3, δ: -3167 (530 Hz).
[PtCl2{NHdC(Et)NdSPh2}] (16). This product was obtained
by the reduction of 2. Anal. Calcd for C15H16N2Cl2PtS: C, 34.49;
H, 3.09; N, 5.36; S, 6.14. Found: C, 35.87; H, 3.17; N, 5.10; S,
304 Inorganic Chemistry, Vol. 42, No. 2, 2003

Platinum(IV)-Mediated Nitrile-Sulfimide Coupling
5.73. FAB+-MS, m/z: 545 [M + Na]+, 522 [M]+, 487 [M - Cl]+.
The complex has no characteristic melting point, and on heating it
gradually decomposes above 220 °C. TLC on Merck 60 F254 SiO2
plates: Rf ) 0.57 (eluent Et2O-CH2Cl2, 1:20). IR spectrum in KBr,
selected bands, cm-1: 3293 m-w ν(N-H), 3051 w and 2926 w
X-ray Structure Determinations.
Data were collected at 150 K with a Bruker SMART 1000 CCD
diffractometer and Mo KR radiation (λ ) 0.710 73 Å) using
ω-rotation and narrow frames (compounds 3, 8, and 21) or with a
Nonius KappaCCD diffractometer (1, 2, and 12). Data were
corrected for absorption semiempirically from equivalent reflections.
Structure 12 was solved by the Patterson method. All other
structures were solved by direct methods and refined by full-matrix
least-squares methods on F2. NH hydrogens in 2, 3, 8, and 21 were
located from the difference map, and their coordinates were freely
refined. NH and NH2 hydrogens in 1 and 12 were also located from
the difference Fourier map but were constrained to ride on their
parent atom. All other hydrogens were placed in geometrical
positions using a riding model. Programs used were Bruker
SMART,22 SAINT,22 SHELXTL,23 DENZO-SCALEPACK,24
SHELXS-97,25 SHELXL97,26 WINGX,27 and local programs. In
the case of 21 (this complex was prepared by the literature route8
and crystallized by slow diffusion of Et2O into an acetonitrile
solution), the data were collected using crystals harvested im-
mediately after growing to the requisite size, thereby obviating an
unavoidable decomposition which occurs in the solid state, even
under inert atmosphere. Crystallographic data are summarized in
Table 1, and selected bond lengths and angles, in Figures 2, 3, and
5-7.
1
ν(C-H), 1523 s ν(CdN), 1446 s ν(CdC Ar). H NMR spectrum
in CDCl3, δ: 8.09 and 7.60 (m, 10H, Ph), 6.49 (s, br, 1H, NH),
2.67 (quart, 7.6 Hz, 2H, CH2 from Et), 1.29 (t, 7.6 Hz, 3H, CH3
from Et). 13C{1H} NMR spectrum in CDCl3, δ: 187.88 (CdN),
135.86 (Cipso), 134.09 (p-Ph), 130.05 and 128.09 (o- and m-Ph),
26.67 (CH2 from Et), 11.80 (CH3 from Et). 195Pt{1H} NMR
spectrum in CDCl3, δ: -3167.9 (485 Hz).
Liberation of the Heterodiazadiene from the Platinum(IV)
Complexes. 31P{1H} NMR monitoring of the reaction between
[PtCl4{NHdC(R)NdSPh2}2] and dppe in CDCl3 shows signals
from the following phosphorus-containing species: [Pt(dppe)2]Cl2
(45.7, JPt-P 2360.5 Hz; lit.16), Ph2P(dO)(CH2)2PPh2 (31.2, d, JP-P
48.5 Hz for Ph2P(dO)(CH2)2PPh2 and -13.5, d, JP-P 48.5 Hz for
Ph2P(dO)(CH2)2PPh2; lit.17-19), Ph2P(dO)(CH2)2P(dO)Ph2 (31.2
s; lit.20) and Ph2P(CH2)2PPh2 (-14.1 s).
In a preparative experiment, dppe (0.12 mmol) is added to a
solution of the complex (0.05 mmol) in CHCl3 (2 mL) at 20-25
°C, whereupon the color turns from orange to colorless for 2 min
and a colorless precipitate is released. The solvent is decanted and
evaporated until half of the initial volume and Et2O (1 mL) is added,
whereupon the mixture is left to stand at ca. -5 °C for 2-3 min.
The precipitate of [Pt(dppe)2]Cl2 is separated by filtration, and the
filtrate is evaporated until dryness. The solids are washed with Et2O
(1 mL) and dried in a vacuum.
Computational Details
The full geometry optimization of all structures has been carried
out in Cartesian coordinates using the quasi-Newton-Raphson
gradient method and the restricted Hartree-Fock approximation
with the help of the GAMESS28 program package. Symmetry
operations were not applied. The single-point calculations at the
MP229 level on the basis of the equilibrium Hartree-Fock
geometries also have been performed to take into account the
electron correlation effects. A quasi-relativistic Stuttgart pseudo-
potential described 60 core electrons, and the appropriate contracted
basis set (8s7p6d)/[6s5p3d] for the platinum atom30 were used. The
standard basis set of Gauss functions 6-31G31,32 was selected for
all other atoms, and d-type of polarization functions with exponent
0.75 and 0.6532,33 were added for the Cl and S atoms, respectively.
NHdC(Me)NdSPh2 (17). FAB+-MS, m/z: 243 [M + H]+. IR
spectrum in KBr, selected bands, cm-1: 3382 s ν(O-H), 3006 w
and 2903 w ν(C-H), 1623 m ν(CdN in L‚HCl), 1528 m ν(CdN
1
in free L, see lit.21), 1437 m ν(CdC Ar). H NMR spectrum in
CDCl3, δ: 9.61 and 9.45 (two s, br, 2H, NH), 7.9-7.2 (m, 10H,
Ph), 1.99 (s, 3H, CH3).
NHdC(Et)NdSPh2 (18). FAB+-MS, m/z: 257 [M + H]+. IR
spectrum in KBr, selected bands, cm-1: 3422 s ν(O-H), 3054 w
and 2926 w ν(C-H), 1648 m ν(CdN in L‚HCl), 1549 m ν(CdN
1
in free L, see lit.21), 1440 m ν(CdC Ar). H NMR spectrum in
CDCl3, δ: 9.55 and 9.40 (two s, br, 2H, NH), 7.9-7.2 (m, 10H,
Ph), 2.69 (quart, 7.5 Hz, 2H, CH2 from Et), 1.25 (t, 7.5 Hz, 3H,
CH3 from Et).
NHdC(Et)NdSPh(o-C6H4SPh) (19). FAB+-MS, m/z: 364
[M]+. IR spectrum in KBr, selected bands, cm-1: 3086 w and 2926
w ν(C-H), 1527 s ν(CdN in free L, see lit.21). 1H NMR spectrum
in CDCl3, δ: 8.15 (d), 7.87 (d), 7.16 (m), 7.01 (m) (C6H4, 4H),
7.7-7.28 (m, 10H, 2Ph), 2.67 (quart, 7.5 Hz, 2H, CH2 from Et),
1.21 (t, 7.5 Hz, 3H, CH3 from Et).
NHdC(Et)NdSPh(p-C6H4SPh) (20). FAB+-MS, m/z: 365
[M + H]+. IR spectrum in KBr, selected bands, cm-1: 3053 w
and 2926 w ν(C-H), 1527 s ν(CdN in free L, see lit.21). 1H NMR
spectrum in CDCl3, δ: 9.59 and 9.40 (two s, br, 2H, NH), 7.8, 7.4
and 7.2 (m, 14H, Ph), 2.67 (quart, 7.5 Hz, 2H, CH2 from Et), 1.25
(t, 7.5 Hz, 3H, CH3 from Et).
(22) SMART and SAINT software for CCD diffractometers; Bruker AXS
Inc.: Madison, WI, 1994.
(23) Sheldrick, G. M. SHELXTL user manual, version 5; Bruker AXS
Inc.: Madison, WI, 1994.
(24) Otwinowski, Z.; Minor, W. DENZO-SCALEPACK “Processing of
X-ray Diffraction Data Collected in Oscillation Mode”. In Methods
in Enzymology, Volume 276, Macromolecular Crystallography; Carter,
C. W., Jr., Sweet, R. M., Eds.; Academic Press: New York, 1997;
Part A, pp 307-326.
(25) Sheldrick, G. M. SHELXS-97; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.
(26) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(27) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.
(28) Schmidt, M. W.; Baldridge, K. K.; Boatz, J. A.; Elbert, S. T.; Gordon,
M. S.; Jensen, J. H.; Koseki, S.; Matsunaga, N.; Nguyen, K. A.; Su,
S. J.; Windus, T. L.; Dupuis, M.; Montgomery, J. A. J. Comput. Chem.
1993, 14, 1347.
(29) (a) Møller, C.; Plesset, M. S. Phys. ReV. 1934, 46, 618. (b) Binkley,
J. S.; Pople, J. A. Int. J. Quantum. Chem. 1975, 9, 229.
(30) Andrae, D.; Haeussermann, U.; Dolg, M.; Stoll, H.; Preuss, H. Theor.
Chim. Acta 1990, 77, 123.
(31) (a) Ditchfield, R.; Hehre, W. J.; Pople, J. A. J. Chem. Phys. 1971, 54,
724. (b) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972,
56, 2257.
(32) Francl, M. M.; Pietro, W. J.; Hehre, W. J.; Binkley, J. S.; Gordon, M.
S.; DeFrees, D. J.; Pople, J. A. J. Chem. Phys. 1982, 77, 3654.
(33) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213.
(16) Anderson, G. K.; Davies, J. A.; Schoeck, D. J. Inorg. Chim. Acta 1983,
76, L251.
(17) Mason, M. R.; Verkade, J. G. Organometallics 1990, 9, 864.
(18) Mason, M. R.; Verkade, J. G. Organometallics 1992, 11, 2212.
(19) Brock, S. L.; Mayer J. M. Inorg. Chem. 1991, 30, 2138.
(20) Calcagno, P.; Kariuki, B. M.; Kitchin, S. J.; Robinson, J. M. A.; Philp,
D.; Harris, K. D. M. Chem.sEur. J. 2000, 6, 2338.
(21) Yoshida, H.; Ogata, T.; Inokawa, S. Bull. Chem. Soc. Jpn. 1977, 50,
3302.
Inorganic Chemistry, Vol. 42, No. 2, 2003 305

Makarycheva-Mikhailova et al.
Table 1. Summary of Crystal Data and Structure Determination for Compounds 1-3, 8, 12, and 21
param
1
2‚CH2Cl2
3
8
12
21
formula
M
C28H28Cl4N4PtS2
821.55
C29H30Cl6N4PtS2
906.48
C30H32Cl4N4PtS2
849.61
C20H18Cl2N2PtS2
616.47
C6H16Cl4N4Pt
481.12
C52H50F12N6P2PtS4
1372.25
cryst dimens
cryst morphology and color
cryst system
space group
a/Å
0.35 × 0.25 × 0.25 0.25 × 0.10 × 0.10 0.59 × 0.27 × 0.17 0.13 × 0.12 × 0.06 0.25 × 0.10 × 0.10 0.90 × 0.50 × 0.20
block, yellow
monoclinic
P21/c
needle, yellow
monoclinic
P21/c
needle, orange
monoclinic
P21/c
block, yellow
monoclinic
P21/n
needle, orange
monoclinic
P21/c
block, yellow
triclinic
P1h
10.9079(2)
13.1920(2)
10.9699(2)
90
94.9210(9)
90
12.5674(4)
18.1314(7)
16.0115(6)
90
107.3600(10)
90
10.9307(4)
12.7847(5)
11.8655(5)
90
93.362(2)
90
9.4631(5)
17.7135(9)
12.4772(7)
90
100.347(2)
90
6.2593(2)
11.8609(4)
9.2909(3)
90
94.656(2)
90
10.2602(9)
10.9478(9)
14.2229(12)
106.369(2)
100.965(2)
110.358(2)
1361.3(2)
1
b/Å
c/Å
R/deg
â/deg
γ/deg
V/Å3
1572.72(5)
2
3482.3(2)
4
1655.30(11)
2
2057.47(19)
4
687.49(4)
2
Z
µ/mm-1
4.959
4.636
4.714
7.291
10.959
2.873
θ range/deg
measd reflcns
indpdt reflcns
Rint
3.75-26.00
18 919
2.61-25.00
20 411
1.87-29.03
14 404
2.02-25.00
14 800
3.69-26.02
8024
2.13-28.70
11 296
3091
6121
4022
2973
1363
6144
0.0381
0.0639
0.0148
0.0340
0.0530
0.0300
R [F2 >2σ(F2)]a
wR2 (all data)b
0.0182
0.0465
0.0138
0.0242
0.0251
0.0333
0.0444
0.1027
0.0339
0.0505
0.0667
0.0848
largest diff map features/e Å-3 0.497, -0.709
2.998, -1.103
0.753, -0.591
1.056, -0.631
1.168, - 1.338
2.995, -2.326
2
2
2
a R ) | |Fo| - |Fc||/|Fo|. b wR2 ) {Σ[w(Fo - Fc )2]/Σ[w(Fo )2]}1/2
.
Scheme 1
Results and Discussion
The sulfimides are a family of organo-sulfur-nitrogen
ylides of formula R2SdNR′.34 Until recently the inorganics
or, more specifically, the coordination chemistrysof sulfim-
ides, in general, and of Ph2SdNH IA, Figure 1 (the most
frequently studied sulfimide), in particular, had been the
subject of few studies. Building on data from a few early
works,35 one of us has found that Ph2SdNH acts as an
effective N-donor ligand to a range of metals.36 Significantly,
the products of such reactions often exhibit important features
such as unexpected isomerism,37 unique unit cell formula-
tion,38 or strong hydrogen bond interactions between the
sulfimide ligands and anions;39 the latter effect has recently
been utilized in the formation of extended metal arrays.40
The feature of the coordination chemistry of Ph2SdNH
which is most pertinent to this work stems from the
observation of the platinum(II)-mediated nucleophilic addi-
tion of a sulfimide to a nitrile.7 In this work, we have taken
this a stage further by not only attempting to liberate the
nitrile addition products of IA but also by investigating the
reactivity of o-{PhS(dNH)}(PhS)C6H4 (IB) and p-{PhS-
(dNH)}(PhS)C6H4 (IC) (Figure 1) toward both Pt(II) and
Pt(IV) centers.
complexes of formula [PtCl4(RCN)2] at room temperature
in CH2Cl2 results in the formation of [PtCl4{NHdC(R)Nd
SPh2}2] (1-5) in ca. 75-90% yields. While trans-[PtCl4-
(RCN)2] (R ) Et, CH2Ph, Ph) leads exclusively to trans-
[PtCl4{NHdC(R)NdSPh2}2] (Scheme 1), cis/trans-[PtCl4-
(MeCN)2] leads to cis/trans mixtures of the products 1 and
2, which can be separated by column chromatography on
silica gel. As noted previously for Pt(II) work,7 such
couplings do not occur in the absence of the metal centers
the sulfimide is inert toward nitriles even at elevated
temperatures.
In addition to microanalysis and FAB mass spectrometry,
the resulting complexes have been characterized by infrared
and NMR spectroscopy. IR spectra show that the CtN
stretching vibrations associated with the starting materials
are replaced by strong ν(CdN) bands at lower frequencies
(1522-1539 cm-1). This range corresponds well to the
Coupling between Platinum(IV)-Bound Nitriles and
Ph2SdNH. Reaction of IA with a range of Pt(IV) nitrile
(34) Oae, S.; Furukawa, N. Sulfilimines and Related DeriVatiVes; American
Chemical Society: Washington, DC, 1983.
(35) (a) Cramer, R. E.; Ariyaratne, K. A. N. S.; Gilje, J. W. Z. Anorg.
Allg. Chem. 1995, 621, 1856. (b) Toriuchi, M.; Matsubayashi, G.;
Koezuka, H.; Tanaka, T. Inorg. Chim. Acta 1976, 17, 253.
(36) E.g., see: Kelly, P. F.; Macklin, A. C.; Slawin, A. M. Z.; Waring, K.
W. Polyhedron 2000, 19, 2077 and references therein.
(37) Kelly, P. F.; Slawin, A. M. Z.; Waring, K. W. J. Chem. Soc., Dalton
Trans. 1997, 2853.
(38) Kelly, P. F.; Slawin, A. M. Z.; Waring, K. W.; Wilson, S. Inorg. Chim.
Acta 2001, 312, 201.
(39) Kelly, P. F.; Slawin, A. M. Z.; Waring, K. W. Inorg. Chem. Commun.
1998, 1, 249.
(40) Holmes, K. E.; Kelly, P. F.; Elsegood, M. R. J. Cryst. Eng. Commun.
2002, 4, 172.
306 Inorganic Chemistry, Vol. 42, No. 2, 2003

Platinum(IV)-Mediated Nitrile-Sulfimide Coupling
Figure 2. ORTEP view of complex 3 with atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. The same numbering
scheme was applied also to structure 1. Selected bond lengths (Å) and angles
(deg) (corresponding values for structure 1 are shown in brackets): Pt(1)-
N(2) 2.0276(14) [2.022(2)], Pt(1)-Cl(1) 2.3279(4) [2.3236(6)], Pt(1)-Cl-
(2) 2.3196(4) [2.3205(6)], N(2)-C(13) 1.309(2) [1.302(3)], C(13)-C(14)
1.500(2), [1.502(4)], C(13)-N(1) 1.355(2) [1.354(3)], N(1)-S(1) 1.6362-
(15) [1.639(2)], S(1)-C(1) 1.792(2) [1.796(3)], S(1)-C(7) 1.778(2) [1.771-
(3)]; N(2)-Pt(1)-Cl(1) 95.09(4) [86.30(6)], N(2)-Pt(1)-Cl(2) 86.14(4)
[86.07(6)], C(13)-N(2)-Pt(1) 137.06(12) [137.0(2)], N(2)-C(13)-C(14)
120.97(15) [121.7(2)], C(13)-N(1)-S(1) 115.60(12) [115.0(2)], C(7)-
S(1)-C(1) 102.30(8) [102.88(12)].
Figure 3. ORTEP view of complex 21 with atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. Selected bond lengths
(Å) and angles (deg): Pt(1)-N(1) 2.023(3), Pt(1)-N(3) 2.034(3), N(2)-
C(1) 1.341(4), S(2)-N(3) 1.618(3), S(2)-C(15) 1.793(3), S(2)-C(21)
1.795(3), N(1)-C(1) 1.306(4), C(1)-C(2) 1.526(4), S(1)-N(2) 1.661(3),
S(1)-C(3) 1.796(3), S(1)-C(9) 1.800(3); S(2)-N(3)-Pt(1) 121.07(15),
C(1)-N(1)-Pt(1) 131.6(2), N(3)-S(2)-C(15) 106.41(15), N(3)-S(2)-
C(21) 110.60(15), N(1)-C(1)-N(2) 129.7(3), N(1)-C(1)-C(2) 116.7(3),
C(1)-N(2)-S(1) 117.2(2), C(3)-S(1)-C(9) 98.44(15).
ν(CdN) values (1530-1540 cm-1) for the previously
reported Pt(II) complexes in which the ligand is either
chelated or monodentate.7,8 In addition, N-H stretching
vibrations are seen in the region 3321-3377 cm-1.
The most significant feature of the 13C{1H} NMR spectra
of the new complexes is the signal from the carbon of the
C)N bond (range 176-180 ppm). The signals in the 195Pt
NMR spectra of the trans complexes occur in the range of
92-135 ppm, while the only isolated cis isomer, i.e. cis-
[PtCl4{NHdC(Me)NdSPh2}2] (2), displays the peak at 188
ppm. The relative position of 195Pt NMR peaks for the
geometrical isomers is consistent with that for other cis/trans-
isomeric pairs of Pt(IV) complexes.41-43
Compounds trans-[PtCl4{NHdC(R)NdSPh2}2] [R ) Me
(1) and Et (3)] have been structurally characterized by X-ray
crystallography, which confirms a Pt(IV) structure with the
two new heterodiazadiene ligands in E-configuration trans
to each other (Figure 2). Calculations investigating the
relative dispositions of the ligands are presented below.
Comparison of the bond lengths and angles within the
heterodiazadiene ligand with those in other systems is
complicated by the fact that the only fully (X-ray crystal-
lographically) characterized complexes contain such ligands
in the chelating mode. The only example of a complex
containing a N-bound monodentate ligand came in the form
of [Pt(NHdSPh2)2{NHdC(Me)NdSPh2}2][PF6]2, which we8
reported but for which we were unable to obtain X-ray
crystallographic data of sufficient quality to ascertain any-
thing more than the connectivity of the molecule. To provide
some context for the structures of trans-[PtCl4{NHdC(R)Nd
SPh2}2] (1-5) we have now revisited this problem and have
successfully solved the structure of [Pt(NHdSPh2)2{NHd
C(Me)NdSPh2}2][PF6]2 (21).
The resulting structure (Figure 3) confirms the presence
of both HNdSPh2 and NHdC(Me)NdSPh2 ligands bound
to the platinum. The bond distances within the latter ligand
are effectively identical to those within the E-NHdC(R)Nd
SPh2 ligands in trans-[PtCl4{NHdC(R)NdSPh2}2] [R ) Me
(1), Et (3)] and also within both E- and Z- NHdC(Me)Nd
SPh2 in cis-[PtCl4(E-NHdC(Me)NdSPh2)(Z-NHdC(Me)Nd
SPh2)] (2) (Figure 4) indicating that neither the oxidation
state of the platinum nor configuration of the ligand appears
to have a great impact upon bond lengths within the addition
ligand. An interesting feature of the structure comes with
the close approach of the sulfur atoms to axial positions
relative to the platinum. The Pt-S distance is 3.0996(8) Å,
which represents a significant long-range intramolecular
interaction; a further example of such an interaction within
one of our complexes is discussed below.
Relative Stability of cis- and trans-(Sulfimide)platinum-
(IV) Complexes. Neither isomer of [PtCl4{NHdC(Me)Nd
SPh2}2] appears to convert to the other upon heating, either
in CH2Cl2 at 40 °C for 2 days or in the solid phase (heated
until the melting point). Both decompose in boiling MeNO2,
again with no evidence for isomerization.
The question of isomer stability in platinum complexes is
a significant one, given the pharmaceutical importance of
many of the compounds. This is because the biological
interactionsssuch as antitumor activityswhich provide the
basis for their use as drugs are often isomer dependent. Thus
while conventional platinum drugs are based on the cis
isomers, some instances of higher activity have been noted
for trans imine complexes.44,45 Such observations have fueled
(41) 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.
(42) Luzyanin, K. V.; Haukka, M.; Bokach, N. A.; Kuznetsov, M. L.;
Kukushkin, V. Yu.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans.
2002, 1882.
(43) Kukushkin, V. Yu.; Belsky, V. K.; Aleksandrova, E. A.; Konovalov,
V. E.; Kirakosyan, G. A. Inorg. Chem. 1992, 31, 3836.
Inorganic Chemistry, Vol. 42, No. 2, 2003 307

Makarycheva-Mikhailova et al.
Figure 4. ORTEP view of complex 2 with atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. Selected bond lengths
(Å) and angles (deg): Pt(1)-N(2) 2.044(7), N(2)-C(13) 1.285(10), C(14)-
C(13) 1.490(11), C(13)-C(14) 1.490(11), N(1)-S(1) 1.636(7), S(1)-C(1)
1.781(9), S(1)-C(7) 1.805(9), Pt(1)-N(2B) 2.030(7), N(2B)-C(13B)
1.303(10), C(13B)-C(14B) 1.515(11), C(13B)-N(1B) 1.345(10), N(1B)-
S(1B) 1.647(7), S(1B)-C(1B) 1.794(9), S(1B)-C(7B) 1.770(8); N(2B)-
Pt(1)-N(2) 91.2(3), Cl(2B)-Pt(1)-Cl(3) 89.98(8), Cl(2B)-Pt(1)-Cl(2)
177.15(8), Cl(2B)-Pt(1)-Cl(3B) 89.88(8), C(13)-N(2)-Pt(1) 135.0(6),
N(2)-C(13)-N(1) 115.2(7), N(2)-C(13)-C(14) 122.7(8), C(13)-N(1)-
S(1) 115.9(6), C(1)-S(1)-C(7) 95.9(4), C(13B)-N(2B)-Pt(1) 133.1(6),
N(2B)-C(13B)-N(1B) 119.8(8), N(2B)-C(13B)-C(14B) 117.1(7), C(13B)-
N(1B)-S(1B) 117.1(6), C(7B)-S(1B)-C(1B) 101.9(4); N(2)‚‚‚N(1B)
2.828(9). Crystal solvent (CH2Cl2) was omitted for clarity.
the search for new drugs on the basis of unconventional
arrangements, such as Pt(IV) complexes with the ligands in
trans geometry. Understanding the relative stabilities of
isomers is crucial to this quest, but in cases such as the cis/
trans isomers of [PtCl4{NHdC(Me)NdSPh2}2], the observed
lack of interconversion means little can be deduced. To
address this issue we have undertaken a computational study
of both isomers.
The full geometry optimization of the trans and cis isomers
of [PtCl4{N(H)dC(Me)NdSMe2}2] (trans-II and cis-II)
have been performed at the Hartree-Fock level, and the
single point calculations at the MP2//HF approach have also
been carried out. The starting geometries of both isomers
corresponded to the experimental X-ray structures of EE-
trans-[PtCl4{N(H)dC(Et)NdSPh2}2] and EZ-cis-[PtCl4-
{N(H)dC(Me)NdSPh2}2] from this work. For cis-II, the
structures of possible conformations of the EE isomer also
have been calculated starting from geometries with different
mutual arrangements of the two N(H)dC(Me)NdSMe2
ligands.
The coordination polyhedra of the Pt atom are octahedral
for all trans and cis species located. The conformations of
the equilibrium structures of trans-II and EZ-cis-II cor-
respond to the experimental ones, i.e., trans-[PtCl4{N(H)d
C(Et)NdSPh2}2] and EZ-cis-[PtCl4{N(H)dC(Me)NdSPh2}2]
(Figure 5). All atoms of the E-N(H)dC(C)NdS fragments
lie in the same plane that passes between the chlorine atoms.
The Z-N(H)dC(C)NdS fragment in EZ-cis-II is not com-
pletely planar; the mean deviation from the plane is 0.098
Figure 5. Calculated equilibrium structures of the complexes trans- and
cis-[PtCl4{N(H)dC(Me)NdSMe2}2].
Å. The main calculated bond lengths in trans-II and EZ-
cis-II are in a good agreement with the X-ray data with the
maximum deviation of 0.052 Å for the Pt-Cl bonds (Table
S38; see Supporting Information). The differences for other
calculated and experimentally found bond lengths do not
exceed 0.029 Å. The structure of EZ-cis-II is stabilized by
intramolecular H-bond NH‚‚‚N with parameters N‚‚‚N,
N-H, and N‚‚‚H of 2.88, 1.00, and 2.05 Å, respectively,
and the NHN angle of 139.7° that is consistent with
experimental data. For EE-cis-II, five minima, associated
with the structures (EE-cis-IIa-e) having different mutual
positions of the imine moieties (Figure 5), were located on
the potential energy surface. The bond lengths all of these
structures are very close to each other as well as to those of
trans-II and EZ-cis-II.
The calculations at both HF//HF and MP2//HF levels show
that the trans isomer is more stable than each conformation
of EE-cis-II as well as of EZ-cis-II (even despite the
intramolecular H-bond for the latter structure) by 5.35-10.88
kcal/mol (HF//HF) and 4.67-8.80 kcal/mol (MP2//HF),
(44) (a) Natile, G.; Coluccia, M. Coord. Chem. ReV. 2001, 216-217, 383.
(b) Liu, Y.; Pacifico, C.; Natile, G.; Sletten, E. Angew. Chem., Int.
Ed. 2001, 40, 1226.
(45) Wong, E.; Giandomenico, C. M. Chem. ReV. 1999, 99, 2451.
308 Inorganic Chemistry, Vol. 42, No. 2, 2003

Platinum(IV)-Mediated Nitrile-Sulfimide Coupling
Table 2. Calculated Total Energies, Etot (Hartree), and Relative
Energies, Erel (kcal/mol), of the Complexes
trans/cis-[PtCl4{N(H)dC(Me)NdSMe2}2]
HF//HF
Etot
MP2//HF
Etot
Erel
Erel
trans-II
-3283.477 243
-3283.466 076
-3283.468 716
-3283.465 490
-3283.465 165
-3283.461 873
-3283.459 897
0.0
7.01
5.35
7.38
7.58
9.64
10.88
-3285.622 819
-3285.613 874
-3285.615 377
-3285.612 487
-3285.613 578
-3285.611 620
-3285.608 788
0.0
EZ-cis-II
EE-cis-IIa
EE-cis-IIb
EE-cis-IIc
EE-cis-IId
EE-cis-IIe
5.61
4.67
6.48
5.80
7.03
8.80
Table 2. Among the cis isomers the most stable one is EE-
cis-IIa with the torsion angles NPtNH of ca. 52°. In previous
works,41,42 the higher stability of trans imino complexes of
platinum compared to their cis isomers was determined
theoretically by us, with a similar energy difference between
the isomeric forms (5.32-13.32 kcal/mol for [PtCl4{NHd
C(H)ONdCH2}2]41 and [PtCl4{N(H)dC(OH)Me}2]42). The
higher stability of trans-(imino)platinum(IV) species agrees
with the direction of the cis-to-trans isomerization observed
for a large number of other platinum(IV) complexes.46 We
anticipate that the absence of the isomerization for cis- and
trans-[PtCl4{NHdC(Me)NdSPh2}2] can be connected with
a rather high kinetic activation barrier when the decomposi-
tion occurs faster than the isomerization.
Coupling between Platinum-Bound Nitriles and Iso-
mers of {PhS(dNH)}(PhS)C6H4. The hybrid sulfide/
sulfimide species o-{PhS(dNH)}(PhS)C6H4 (IB) and p-{PhS-
(dNH)}(PhS)C6H4 (IC) (Figure 1) react with both Pt(II) and
Pt(IV) nitrile complexes in an fashion analogous to that for
IA (see Experimental Section and ref 7). In the case of Pt(II),
the most readily crystallized product from such reactions
comes in the form of [PtCl2{NHdC(Me)NdS(Ph)C6H4SPh-
o}] (8), which is generated by reaction of the sulfimide with
[PtCl2(MeCN)2] and isolated in ca. 50% yield while the
mother liquor contains a mixture of yet unidentified species.
The X-ray crystal structure of the latter product (Figure
6) reveals bond parameters within the metallacycle (see
below) little different from those in previously reported [PtCl-
(NHdSPh2){NHdC(Me)NdSPh2}]Cl.7 As Figure 6 shows,
the thioether unit of the ligand orientates itself in such a way
as to leave the phenyl end unit as far away from the rest of
the atoms of the molecule as possible. While steric consid-
erations no doubt provide one driving force for the adoption
this orientation, another interesting feature of the structure
is the close interaction of the thioether sulfur atom with the
platinum. As Figure 6 shows, this atom approaches the axial
position of the platinum, resulting in a Pt-S distance of 3.446
Å. This distance is slightly longer than that observed in [Pt-
(NHdSPh2)2{NHdC(Me)NdSPh2}2][PF6]2 (21); both values
compare well with those observed in a number of recent
examples of complexes exhibiting axial Pt-S interactions.
For example, such interactions (in this case slightly shorter,
at 3.3 Å or less) result in dimer formation within [ClCr(4-
mpyt)4Pt] (mpyt ) 4-methylpyridine-2-thiolate).47 The Cl-
Figure 6. ORTEP view of complex 8 with atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. Selected bond lengths
(Å) and angles (deg): Pt(1)-N(1) 1.993(4), Pt(1)-S(2) 2.1748(12), Pt-
(1)-Cl(2) 2.2794(13), Pt(1)-Cl(1) 2.3267(13), S(1)-C(7) 1.771(5), S(1)-
C(1) 1.783(5), C(19)-N(1) 1.297(6), C(19)-C(20) 1.510(7), N(2)-C(19)
1.347(6), S(2)-N(2) 1.632(4), S(2)-C(13) 1.788(5), S(2)-C(12) 1.788-
(5), Cl(2)-Pt(1)-Cl(1) 91.87(5), C(7)-S(1)-C(1) 101.4(2); N(2)-S(2)-
Pt(1) 107.12(15), C(13)-S(2)-Pt(1) 111.96(16), C(12)-S(2)-Pt(1) 119.21-
(15), N(1)-C(19)-N(2) 123.2(4).
(1)-Pt-S(1) angle (100.3°) also provides an indication of
the presence of a significant Pt-S interaction.
Acid-Catalyzed Hydrolysis of [PtCl4{NHdC(R)Nd
SPh2}2]. Solution NMR studies reveal that all the complexes
of formula [PtCl4{NHdC(R)NdSPh2}2] (1-5) are stable
toward [Bu4N]OH (10 equiv); acidification with CF3CO2H,
however, results in some irreversible changes. Thus in each
case, apart from trans-[PtCl4{NHdC(Me)NdSPh2}2] (1),
treatment with HCl in (undried) CH2Cl2 releases a crystalline
material which proves to be an amidine-platinum(IV)
complex of formula [PtCl4{NHdC(NH2)R}2] (11-14).
Analysis of the reaction mixtures by TLC and mass
spectrometry reveals that diphenyl sulfoxide also forms,
indicating that the reactions correspond to the acid-catalyzed
hydrolysis shown in Scheme 2 (monochloro- and dichloro-
diphenyl sulfides, formed as secondary products on deoxy-
genation of Ph2SO with HCl,48 can also be detected in the
reaction mixture). In one case, i.e. the reaction between trans-
[PtCl4{NHdC(Me)NdSPh2}2] (1) and HCl, the product
released as the solid was different from the amidine
complexes. On the basis of elemental analyses and FAB and
IR spectroscopy, it is tentatively formulated as the protona-
tion product trans-[PtCl4{NHdC(Me)NdSPh2}2]‚(HCl)2‚
2H2O (10). However, its poor solubility in both water and
in the most common organic solvents precluded NMR study
and further structural characterization.
The X-ray structural study of trans-[PtCl4{NHdC(NH2)-
Et}2] (12) (Figure 7) showed that the two amidines are in
trans position to each other and these species are in
Z-configuration. The latter implies that the configuration of
the imino species changes from E to Z upon the hydrolysis.
(47) Kitano, K.; Tanaka, R.; Kimura, T.; Tsuda, T.; Shimizu, S.; Tagaki,
H.; Nishioka, T.; Shiomi, D.; Ichimura, A.; Kinoshita, I.; Isobe, K.;
Shun’ichiro, O. J. Chem. Soc., Dalton Trans. 2000, 995.
(46) Kukushkin, V. Yu. Russ. J. Inorg. Chem. (Engl. Transl.) 1988, 33,
1085.
(48) Kukushkin, V. Yu. Coord. Chem. ReV. 1995, 139, 375.
Inorganic Chemistry, Vol. 42, No. 2, 2003 309

Makarycheva-Mikhailova et al.
noted, as have photolysis/thermolysis reactions (which gener-
ate heterocycles).59 One reason for this lack of chemistry is
undoubtedly that fact that few synthetic methods for prepara-
tion of such compounds have been reported and so only a
limited number of heterodiazadienes of this type have ever
been prepared. In addition, most of examples prepared so
far contain alkyl or aryl groups in the R1 position; to the
best of our knowledge there is only one documented example
of compounds bearing R1 ) H, i.e. HNdC(Ph)NdSMe2,60
which has been synthesized via chlorination of HNdC(Ph)-
NH2 with NaClO to give ClNdC(Ph)NH2, followed by
reaction of the latter with Me2S to achieve [HNdC(Ph)-
N-+SMe2]Cl-. The sulfonium salt is converted to HNd
C(Ph)NdSMe2 by the reaction with NaOH.60
Figure 7. ORTEP view of complex 12 with atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. Selected bond lengths
(Å) and angles (deg): Pt(1)-Cl(1) 2.3196(13), Pt(1)-Cl(2) 2.3232(13),
Pt(1)-N(1) 2.033(4), C(1)-N(1) 1.305(7), C(1)-N(2) 1.315(7), C(1)-C(2)
1.515(7), C(2)-C(3) 1.508(9); Pt(1)-N(1)-C(1) 133.3(4), N(1)-C(1)-
N(2) 124.2(5), N(1)-C(1)-C(2) 119.3(5), N(2)-C(1)-C(2) 116.5(5),
C(3)-C(2)-C(1) 111.9(5).
Scheme 2
We found that the ligands formed upon Pt(IV)-mediated
RCN/sulfimide coupling can be liberated from the platinum-
(IV) complexes by reaction with Ph2PCH2CH2PPh2 (dppe)
(Scheme 1). The role of dppe is dual, i.e. it reduces the Pt-
(IV) center [reduction of (imine)platinum(IV) species by
PPh3 is known61] and substitutes the ligated heterodiazadienes
(17-20). The latter were characterized in solution by 1H and
13C{1H} NMR methods, while the dppe oxides were unam-
biguously identified by running the 31P{1H} NMR spectra
of the reaction mixtures and comparing the observed chemi-
cal shifts with those known from the literature (see Experi-
mental Section). The liberated ligands were isolated as solids
after addition of Et2O to the reaction mixture and additionally
characterized by FAB-MS and IR spectroscopy.
Previously our group9,52 and Michelin et al.1d observed that
the liberation of ligated imines is efficient when (imine)-
platinum(II) complexes are treated with bidentate diphos-
phines in CH2Cl2 to give quantitative yield of the imine in
solution and the solid [Pt(diphosphine)2]Cl2. The phosphorus
ylide Ph3PdCHCO2Me has previously proved to be a mild
and selective reducing agent for the conversion of Pt(IV)
complexes to appropriate Pt(II) compounds in nonaqueous
solvents.62 Unfortunately, attempts to reduce [PtIVCl4{NHd
C(R)NdSPh2}2] to [PtIICl2{NHdC(R)NdSPh2}2] using the
latter ylide proved unsuccessful. In the cases of [PtCl4{NHd
C(R)NdSPh2}2] [R ) Me (1), Et (3)], only the previously
described chelate [PtCl2{NHdC(Me)NdSPh2}]8 (15) and the
similar complex [PtCl2{NHdC(Et)NdSPh2}] (16)sboth
obtained upon reduction, elimination of one of the sulfimide
All bond lengths and angles are normal for coordinated
amidines49-51 and for chloroplatinum(IV) complexes.41,42,52-54
Interestingly, despite the fact that the X-ray crystal-
lographic determination of the structure of amidine platinum-
(II) complexes proved an important landmark in developing
the metalla-Pinner reaction,2 until now no platinum(IV)
analogues have been fully characterized; the structure
reported here is the first one of that kind.
Liberation of the Ligated Heterodiazadienes. Despite
the wealth of chemistry associated with sulfimides in general,
the chemistry of heterodiazadienes of the type R1Nd
C(R2)NdSR3 (R1 ) H, alkyl, aryl) has so far been little
2
explored, although reactions of R1NdC(R2)NdSR3 (R1 )
2
alkyl, aryl) with CS2,55 nitrile oxides,56 enamines,57 and
diphenylcyclopropenone (to give 4-pyrimidones)58 have been
(55) Yoshida, H.; Ogata, T.; Inokawa, S. Bull. Chem. Soc. Jpn. 1977, 50,
3302.
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310 Inorganic Chemistry, Vol. 42, No. 2, 2003

Platinum(IV)-Mediated Nitrile-Sulfimide Coupling
derived ligands and ring-closureswere separated by column
chromatography from other products, while in all of the other
cases broad mixtures of yet unidentified compounds were
obtained. Although we could so far liberate the sulfimide
derived heteroazadienes only when starting from the plati-
num(IV) complexes, it is believed that preparation of the
novel sulfimides by the metal-mediated RCN/sulfimide
coupling followed by their liberation opens up a facile route
to this class of compounds and could initiate their further
exploration and utilization.
metal centers, i.e. Pt(IV),41,53,54,64-66 Re(IV),67 Rh(III),68 and
Au(III),69 point out to the need of further investigations,
including possibly theoretical studies, of the nature of the
M-NdC linkage for the imino complexes.
The ability to isolate the free heterodiazadiene from these
reactions provides us with the opportunity to prepare new
classes of polydentate ligands. Even when the heterodiaza-
dienes generated in the coupling reactions are bound in the
monodentate fashion through the nitrogen, the sulfimide
sulfur atom has a tendency toward fulfilling a coordination
role, as the axial Pt-S interaction within [Pt(NHdSPh2)2-
{NHdC(Me)NdSPh2}2][PF6]2 (21) reveals. It would seem
that the coupling reaction greatly increases the metal affinity
of these sulfur atoms (bearing in mind that no S-bound
complexes of simple sulfimides are known). Likewise, the
axial interaction of the sulfur atom of the C6H4SPh group
observed in [PtCl2{NHdC(Me)NdS(Ph)C6H4SPh-o}] (8)
indicates that atoms within the functional groups bound to
the sulfimidic sulfur atom can also play a coordination role.
Given that one can envisage the preparation of sulfimides
of the general type HNdS(C6H4X)(Ph), wherein X is a
coordinating group, it follows that the Pt(IV)-mediated
coupling/liberation reactions could provide routes to new
tridentate ligand systems.
Final Remarks
From the work reported herein it is clear that the
coordination mode of the heterodiazadiene species formed
during the Pt-mediated RCN/HNdSPh2 coupling depends
on the oxidation state of the metal. In the case of reaction at
Pt(IV) centers, the coupling brings about the formation of
complexes bearing the heterodiazadiene bound monoden-
tately via the imino nitrogen. While this monodentate
coordination mode is actually desirable, in that it is a key to
the ease of liberation of the new heterodiazadienes, we have
yet to find a way to convert such complexes to bidentate
examples without concomitant reduction to Pt(II). In the case
of Pt(II) complexes there appears to be a clear tendency
toward the bidentate coordination mode. Thus earlier re-
ports7,8 by one of us of the latter within [PtCl(NHdSPh2)-
{NHdC(Me)NdSPh2}]Cl and [PtCl2{NHdC(Me)NdSPh2}]2‚
[PPh4]Cl are augmented by the observation of a bidentate
coordination mode for derivatives of the bifunctional sulfim-
ides used in the current study. However, we need to respect
the caVeat that conversion from bidentate to monodentate
via substitution at the Pt-S bond is possible, as the structure
of [Pt(NHdSPh2)2{NHdC(Me)NdSPh2}2][PF6]2 (21) con-
firms.
A similar oxidation state dependence of coordination
patterns has been observed for the NHdC(R′)ONdCR2
species formed in the metal-mediated nitrile-oxime cou-
pling. Indeed, the N,N-chelates are formed at Pt(II) centers,63
while exclusively monodentate coordination of the imino
species has been found at Pt(IV) centers.41,53,54 In addition,
the monodentate coordination at a Pt(IV) centerswhen all
conditions for the formation of the stable 5-membered rings
are favorableswas found for the iminoacylated hydroxamic
acids,64 hydroxylamines,65 and dione monoximes.66 We
anticipate that the stability of Pt(IV) complex with two
monodentate imino ligands is higher than that with the
chelated ligand containing only one imino group. The above-
mentioned facts, combined with data on the enormously high
hydrolytic stability of imino species at high oxidation state
Acknowledgment. A.V.M.-M. is indebted to the Gov-
ernor of St. Petersburg for a fellowship (Grant M01-2.5D-
446). N.A.B. thanks INTAS for the grant YSF 2002-93.
A.V.M.-M., N.A.B., and V.Y.K. express gratitude to the
International Science Foundation (Soros Foundation) for the
fellowships, while V.Yu.K. additionally thanks the Royal
Society of Chemistry for a Grant for International Authors.
M.L.K. and V.Yu.K. are very much obliged to the PRAXIS
XXI and POCTI programs (Portugal) for the Grants
BPD16369/98//BPD/5558/2001 and BCC16428/ 98, cor-
respondingly. A.J.L.P. and V.Yu.K. are grateful to the FCT
(Foundation for Science and Technology) (Portugal) and the
PRAXIS XXI and POCTI programs for financial support of
these studies. P.F.K. is grateful to the EPSRC for studentship
(K.E.H. and J.M.S.) and PDRA (L.M.G., Grant GR/N28221)
support and to Johnson Matthey for loans of precious metals.
Supporting Information Available: Tables S1-S37, listing
crystallographic data, atomic coordinates, bond lengths and bond
angles, anisotropic displacement parameters, hydrogen coordinates,
and isotropic displacement parameters for all structures, torsion
angles for 1, 2, 12, and 21, and hydrogen bonds for 2, 12, and 21,
X-ray crystallographic files in CIF format, and Table S38 with
selected calculated bond lengths of the complexes. This material
is available free of charge via the Internet at http://pubs.acs.org.
IC025960W
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