Coupling between 3-iminoisoindolin-1-ones and complexed isonitriles as a metal-mediated route to a novel type of palladium and platinum iminocarbene species

Article abstract of DOI:10.1021/om800517c

The reaction between isonitrile in cw-[MCl₂(C=NR)₂] [M = Pd, R = Cy 1, Bu^t 2, C₆H₃(2,6-Me ₂) 3; M = Pt, R = Cy 4, Bu^t 5, C₆H ₃(2,6-Me₂) 6] and various unsubstituted or substituted iminoisoindolin-1-ones HN=CC₆R¹R²R ³R⁴CONH [R₁ - R₄ = H 7; R ₁, R₃, R₄ = H, R₂ = Me/R ₁, R₂, R₄ = H, R₃ = Me 8 (isomeric mixture); R₁, R₄ = H, R₂, R₃ = Cl 9] proceeds under reflux conditions in CHCl₃ for 2 h. The subsequent workup provides complexes [MC1{C(N=C(C₆R¹R ²R³R⁴CON))=N(H)R}(C≡NR)] (M = Pd, 10-18; M = Pt, 19-27), bearing a novel type of carbene ligands, which were isolated in good (80-85% for the Pd^II complexes) to moderate (60-65% for the Pt^II species) yields. The addition of the iminoisoindolin-1-one to isonitriles is metal-mediated and has a general character. The reaction of cis-[PtCl₂(C=NC₆H₄OMe-4)₂] (28) with 7 affords a mixture of Pt^II-containing species including the monoadduct [PtCl{C(N=C(C₆H₄CON))=N(H)C₆H ₄OMe-4}(C≡NC₆H₄OMe-4)] (29), the unusual binuclear compound [Pt₂{C(N=C(C₆H₄CON))=N(H) C₆H₄OMe-4}₂(C≡NC₆H ₄OMe-4)₂(μ-HN=CC₆H₄-CON)](Cl) (30) with a bridging monodeprotonated 3-iminoisoindolin-1-one, and [Pt(C ₆H₄CONC= NH){C(N=C(C₆H₄CON))=N(H) C₆H₄OMe-4}(C≡NC₆H₄OMe-4)] (31), the latter resulting from the replacement of the chloro ligand in 29 by the deprotonated iminoisoindolin-1-one. Complexes 10-27 were characterized by elemental analyses (C, H, N), ESI⁺-MS, IR, and ID (¹H, ¹³C{¹H}) and 2D (¹H,¹H-COSY, ¹H,¹³C-HMQC/¹H,¹³C-HSQC, ¹H,¹³C-HMBC) NMR spectroscopies, while 29-31 by ESI ⁺-MS, IR, and ¹H NMR. In addition, the structures of three carbene complexes (10, 27, and 30) were elucidated by single-crystal X-ray diffraction analysis.

Full text of DOI:10.1021/om800517c

Organometallics 2008, 27, 5379–5389
5379
Coupling between 3-Iminoisoindolin-1-ones and Complexed
Isonitriles as a Metal-Mediated Route to a Novel Type of Palladium
and Platinum Iminocarbene Species
Konstantin V. Luzyanin,†,‡ Armando J. L. Pombeiro,*,† Matti Haukka,§ and
Vadim Yu. Kukushkin*,‡,
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, TU Lisbon, AVenida RoVisco Pais,
1049-001 Lisbon, Portugal, St.Petersburg State UniVersity, 198504 Stary Petergof, Russian Federation,
Department of Chemistry, UniVersity of Joensuu, P.O. Box 111, FI-80101, Joensuu, Finland, and Institute
of Macromolecular Compounds of the Russian Academy of Sciences, Bolshoii Pr. 31,
199004 St.Petersburg, Russian Federation
ReceiVed June 5, 2008
The reaction between isonitrile in cis-[MCl2(Ct NR)2] [M ) Pd, R ) Cy 1, But 2, C6H3(2,6-Me2) 3;
M ) Pt, R ) Cy 4, But 5, C6H3(2,6-Me2) 6] and various unsubstituted or substituted iminoisoindolin-
1-ones HNdCC6R1R2R3R4CONH [R1-R4 ) H 7; R1, R3, R4 ) H, R2 ) Me/R1, R2, R4 ) H, R3 ) Me
8 (isomeric mixture); R1, R4 ) H, R2, R3 ) Cl 9] proceeds under reflux conditions in CHCl3 for 2 h. The
subsequent workup provides complexes [MCl{C(NdC(C6R1R2R3R4CON))dN(H)R}(Ct NR)] (M ) Pd,
10-18; M ) Pt, 19-27), bearing a novel type of carbene ligands, which were isolated in good (80-85%
for the PdII complexes) to moderate (60-65% for the PtII species) yields. The addition of the
iminoisoindolin-1-one to isonitriles is metal-mediated and has a general character. The reaction of cis-
[PtCl2(Ct NC6H4OMe-4)2] (28) with 7 affords a mixture of PtII-containing species including the
monoadduct [PtCl{C(NdC(C6H4CON))dN(H)C6H4OMe-4}(Ct NC6H4OMe-4)] (29), the unusual bi-
nuclear compound [Pt2{C(NdC(C6H4CON))dN(H)C6H4OMe-4}2(Ct NC6H4OMe-4)2(µ-HNdCC6H4-
CON)](Cl) (30) with a bridging monodeprotonated 3-iminoisoindolin-1-one, and [Pt(C6H4CONCd
NH){C(NdC(C6H4CON))dN(H)C6H4OMe-4}(Ct NC6H4OMe-4)] (31), the latter resulting from the
replacement of the chloro ligand in 29 by the deprotonated iminoisoindolin-1-one. Complexes 10-27
were characterized by elemental analyses (C, H, N), ESI+-MS, IR, and 1D (1H, 13C{1H}) and 2D (1H,1H-
COSY, 1H,13C-HMQC/1H,13C-HSQC, 1H,13C-HMBC) NMR spectroscopies, while 29-31 by ESI+-MS,
IR, and 1H NMR. In addition, the structures of three carbene complexes (10, 27, and 30) were elucidated
by single-crystal X-ray diffraction analysis.
The heteroatom-stabilized (carbene)[M] species, especially
those with N-containing heterocycles, are prominent in orga-
nometallic catalysis, e.g. for hydrosylation of alkenes,7b and in
a wide range of cross-coupling systems (e.g., Heck, Suzuki,
Suzuki-Miyaura, Sonogashira, Kosugi-Migita, and Stille
Introduction
Isonitriles, RNt C, are versatile reagents in organic and
organometallic chemistry, and their transformations allow the
synthesis of a wide range of important products.1 Besides the
application of uncomplexed isonitriles for the stereoselective
synthesis of bis-amides, heterocycles, and peptides via the so-
called multicomponent reactions,1-3 RNt C species also attract
attention in coordination chemistry due to their ability to form
a diversity of types of complexes including aminocarbynes4,5
and heteroatom-stabilized metallacarbenes6,7 (Scheme 1).
Scheme 1. Generation of Heteroatom-Stabilized Carbene
Complexes via Nucleophilic Addition to Metal-Bound
Isonitriles and Direct Complexation
* Corresponding authors. E-mail: pombeiro@ist.utl.pt; kukushkin@
VK2100.spb.edu.
† Instituto Superior Te´cnico.
‡ St. Petersburg State University.
§ University of Joensuu.
Institute of Macromolecular Compounds.
(1) Isonitrile Chemistry, Organic ChemistrysA Series of Monographs;
Ugi, I., Ed.; Academic Press: New York, 1971.
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Chapters 4, 6. (b) Ugi, I., Marquarding, D.; Urban, R. Syntheses of peptides
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10.1021/om800517c CCC: $40.75
2008 American Chemical Society
Publication on Web 09/25/2008

5380 Organometallics, Vol. 27, No. 20, 2008
Luzyanin et al.
Scheme 2. Interplay between Ph2CdNH and Pt-Bound Isonitrile Species Producing Aminoimino-Carbene and the Detected
Decomposition and/or Side Products
reactions).7a,8 Moreover, some of these carbenes exhibit lumi-
nescent properties.7b
of the iminoisoindolin-1-ones toward isonitriles at these two
metal centers. Our results are disclosed in the sections that
follow.
Two general routes for the preparation of heteroatom-
stabilized metallacarbenes are commonly utilized, viz., the
coordination of preprepared free carbenes to a metal center, and
the transformation of the metal-bound isonitrile upon nucleo-
philic attack (Scheme 1). The former method is limited mostly
to imidazol-2-ylidene, 1,2,4-triazole-3-ylidene, and 1,3-thiazol-
2-ylidene derivatives with bulky substituents (some noncyclic
species are also known7) due to an insufficient stability of the
uncomplexed carbenes, while the limitation of the latter route
is the relatively low electrophilic activation of the isonitriles.
However, the metal-mediated approach appears to be more
versatile than the route associated with the direct complexation
due to the wide range of available nucleophiles and isonitriles,
thus providing a great variety of (carbene)[M] species.
Reactions of complexed isonitriles with nucleophiles have
been repeatedly reviewed6,7 (including a survey by one of us6),
showing that the vast majority of the reported examples are
based on the addition of nucleophiles with sp3-N or O donor
centers, viz. amines and alcohols.6,7 In this context, additions
of sp3-N nucleophiles, viz. ammonia or primary or secondary
amines, to metal-bound RNC molecules are well documented,
and this interaction brings about formation of the amino-carbene
C(NRt R′′)N(H)R ligands.6
Results and Discussions
General Approach. Recently, we reported on the coupling
of a Pt-bound isonitrile with an imine, i.e., benzophenone imine,
affording an aminoimino-carbene complex A depicted in
Scheme 2, which derived from a nucleophilic attack of the sp2-N
center on the isonitrile C atom.9 However, the reaction proceeds
nonselectively and the obtained aminoimino-carbene species is
unstable even at room temperature. It was characterized
spectroscopically in the reaction mixture, while its isolation as
a solid failed due to easy hydrolytic conversion to the diamino-
carbene cis-[PtCl2(Ct NR){C(NH2)N(H)R}] (B), while forma-
tion of the related complex C was also observed.
Following our ongoing project on metal-mediated and/or
metal-catalyzed activation of small molecules10 (viz. dinitro-
gen,11 alkanes,12,13 carbon monoxide,14 cyanides,15 oximes,16,17
nitriles,18-20 and isonitriles4-6,21) we have recently discovered
that iminoisoindolin-1-onesswhich represent a family of stable
aromatic iminessexhibit nucleophilic properties toward metal-
bound organonitriles RCt N. It is important that iminoisoin-
In contrast to the additions of nucleophiles with sp3-N donor
centers, the interaction of isonitriles with sp2-N nucleophiles
such as imines is almost unexplored. Thus, only recently, we
reported evidence for the integration between a Pt-bound
isonitrile and benzophenone imine, affording an aminoimino-
carbene complex, which rapidly decomposes in solution prior
to isolation.9 Herein we report on the first unequivocally
confirmed examples for the coupling between an imine and
complexed isonitriles. Our aims were threefold: (i) to study the
coupling between PdII- and PtII-bound isonitriles and sp2-N
nucleophiles such as iminoisoindolin-1-ones, (ii) to characterize
the complexes formed upon this coupling and bearing iminocar-
bene ligands of a novel type, and (iii) to compare the reactivity
(7) (a) Cavell, K. J.; McGuiness, D. S. Palladium complexes with
carbonyl, isocyanide and carbene ligands. In ComprehensiVe Organometallic
Chemistry III, 1st ed.; Canty, A., Ed.; Elsevier: Oxford, 2007; Vol. 8,
Chapter 8.04, pp 197-268. (b) Rourke, J. P. Platinum complexes with
carbonyl, isocyanide and carbene ligands. In ComprehensiVe Organometallic
Chemistry III, 1st ed.; Canty, A., Ed.; Elsevier: Oxford, 2007; Vol. 8,
Chapter 8.07, pp 405-444.
(8) Nolan, S. P.; Navarro, O. C-C bond formation by cross-coupling.
In ComprehensiVe Organometallic Chemistry III, 1st ed.; Canty, A., Ed.;
Elsevier: Oxford, 2007; Vol. 11, Chapter 11.01, pp 1-38, and references
therein.
(9) Luzyanin, K. V.; Guedes da Silva, M. F. C.; Kukushkin, V. Yu.;
Pombeiro, A. J. L. Inorg. Chim. Acta (Topical Volume Dedicated to B.
Lippert), 2008,. in press (doi: 10.1016/j.ica.2008.02.026).
(10) Pombeiro, A. J. L.; Kukushkin, V. Yu. Ligand Reactivity: General
Introduction. In ComprehensiVe Coordination Chemistry, 2nd ed.; Lever,
A. B. P., Ed.; Elsevier: New York, 2004; Vol. 1, Chapter 1.29, pp 585-
594.
(4) Pombeiro, A. J. L.; Guedes da Silva, M. F. C.; Michelin, R. Coord.
Chem. ReV. 2001, 218, 43–74.
(11) (a) Pombeiro, A. J. L.; Costa, M. T. A. R. S.; Wang, Y.; Nixon,
J. F. J. Chem. Soc., Dalton Trans. 1999, 3755–3758. (b) Cunha, S. M. P. R.
M.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L. J. Chem. Soc., Dalton
Trans. 2002, 1791–1799. (c) Cunha, S. M. P. R. M.; Guedes da Silva,
M. F. C.; Pombeiro, A. J. L. Inorg. Chem. 2003, 42, 2157–2164. (d) Kirillov,
A. M.; Haukka, M.; Guedes da Silva, M. F. C.; Frau´sto da Silva, J. J. R.;
Pombeiro, A. J. L. J. Organomet. Chem. 2006, 691, 4153–4158. (e)
Smolenski, P.; Pombeiro, A. J. L. Dalton Trans. 2008, 87–91.
(5) (a) Guedes da Silva, M. F. C.; Frau´sto da Silva, J. J. R.; Pombeiro,
A. J. L.; Pellinghelli, M. A.; Tiripicchio, A. J. Chem. Soc., Dalton Trans.
1996, 2763–2772. (b) Pombeiro, A. J. L.; Guedes da Silva, M. F. C. J.
Organomet. Chem. 2001, 617-618, 65–69.
(6) Michelin, R.; Pombeiro, A. J. L.; Guedes da Silva, M. F. C. Coord.
Chem. ReV. 2001, 218, 75–112.

Palladium and Platinum Iminocarbene Species
Organometallics, Vol. 27, No. 20, 2008 5381
Figure 1. Iminoisoindolin-1-one, (1,3,5-triazapentadienato)[M] chelates, and metallacarbenes.
dolin-1-ones have an endocyclic auxiliary amide functionality,
which upon deprotonation might be involved in the complex-
ation forming relatively stable chelated metallacycles (Figure
1). Thus, the interplay between iminoisoindolin-1-ones and
metal-bound organonitriles leads to the formation of unsym-
nitriles (chelated 1,3,5-triazapentadienato species) prompted us
to amplify this type of chemistry to the isomeric isonitriles, and
thus we decided to employ iminoisoindolin-1-ones for coupling
with palladium(II)- and platinum(II)-bound isonitriles. For this
study we addressed, on one hand, the known palladium(II)24
and platinum(II)24 isonitrile complexes cis-[MCl2(Ct NR)2] [M
) Pd, R ) cyclohexyl (Cy) 1, But 2, C6H3(2,6-Me2) 3; M )
Pt, R ) Cy 4, But 5, C6H3(2,6-Me2) 6] and, on the other hand,
various unsubstituted (3-iminoisoindolin-1-one 7) or substituted
(isomeric mixture 5-methyl-3-iminoisoindolin-1-one/6-methyl-
3-iminoisoindolin-1-one 8 or 5,6-dichloro-3-iminoisoindolin-
1-one 9) iminoisoindolin-1-ones.25
Metal-Mediated Addition of Iminoisoindolin-1-ones to
Coordinated Isonitriles. The interaction between cis-
[MCl2(C′NR)2] (1-6) and iminoisoindolin-1-ones (7-9) in
CHCl3 (Schemes 3 and 4, Table 1) was studied at different
temperatures. Thus, when cis-[MCl2(Ct NBut)2] (M ) Pd 2,
Pt 5) and the unsubstituted iminoisoindolin-1-one (7) were used
as the starting materials, the reaction mixtures rapidly (ca. 5
min, 20-25 °C) changed their color from pale yellow to intense
lemon-yellow, following the dissolution of the initial solid of
7. In the case of PdII, the system contains a ca. 2:8 mixture
(based on TLC and 1H NMR integration data) of the
[PdCl(C6H4CONCNH)(Ct NBut)2] (33) and [PdCl{C(Nd
C(C6H4CON))dN(H)But}(Ct NBut)] (13) complexes (Scheme
3). After 2 h at 20-25 °C, the reaction mixture contained only
13 (ca. 85%) along with some other byproduct, while 33 was
no longer detected.
metrical (1,3,5-triazapentadienato)[M] (M ) NiII,22 CuII 23
)
complexes (Figure 1).
These observations on the stability of the imine (i.e.,
iminoisoindolin-1-one) and of the products of its addition to
(12) (a) Reis, P. M.; Silva, J. A. L.; Palavra, A. F.; Frau´sto da Silva,
J. J. R.; Kitamura, T.; Fujiwara, Y.; Pombeiro, A. J. L. Angew. Chem., Int.
Ed. 2003, 42, 821–823. (b) Kirillov, A. M.; Kopylovich, M. N.; Kirillova,
M. V.; Haukka, M.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L. Angew.
Chem., Int. Ed. 2005, 44, 4345–4349. (c) Kirillov, A. M.; Haukka, M.;
Kirillova, M. V.; Pombeiro, A. J. L. AdV. Synth. Catal. 2005, 347, 1435–
1446. (d) Reis, P. M.; Silva, J. A. L.; Palavra, A. F.; Frau´sto da Silva,
J. J. R.; Pombeiro, A. J. L. J. Catal. 2005, 235, 333–340. (e) Kirillov, A. M.;
Kopylovich, M. N.; Kirillova, M. V.; Karabach, E. Yu.; Haukka, M.; Guedes
da Silva, M. F. C.; Pombeiro, A. J. L. AdV. Synth. Catal. 2006, 348, 159–
174. (f) Mishra, G. S.; Pombeiro, A. J. L. J. Appl. Catal. A: Gen. 2006,
304, 185–194.
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Mol. Catal. A: Chem. 2006, 265, 59–69. (b) Kirillova, M. V.; Kirillov,
A. M.; Reis, P. M.; Silva, J. A. L.; Frau´sto da Silva, J. J. R.; Pombeiro,
A. J. L. J. Catal. 2007, 248, 130–136. (c) Kirllova, M. V.; Kuznetsov, M. L.;
Reis, P. M.; Silva, J. A. L.; Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L.
J. Am. Chem. Soc. 2007, 129, 10531–10545. (d) Kirillova, M. V.; Da Silva,
J. A. L.; Frau´sto da Silva, J. J. R.; Palavra, A. F.; Pombeiro, A. J. L. AdV.
Synth. Catal. 2007, 349, 1765–1774. (e) Kirillova, M. V.; Da Silva, J. A. L.;
Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L Appl. Catal. A: Gen. 2007,
332, 159–165. (f) Kirillova, M. V.; Kuznetsov, M. L.; Silva, J. A. L.; Guedes
da Silva, M. F. C.; Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L. Chem.-
Eur. J. 2008, 14, 1828–1842. (g) Silva, T. F. S.; Alegria, E. C. B. A.;
Martins, L. M. D. R. S.; Pombeiro, A. J. L. AdV. Synth. Catal. 2008, 350,
706–716.
In the case of PtII, the reaction solution contains comparable
amounts of [PtCl(C6H4CONCNH)(Ct NBut)2] (34) and [PtCl-
{C(NdC(C6H4CON))dN(H)But}(Ct NBut)] (22) along with
some yet unidentified species (three spots on TLC apart from
those of 34 and 22). Complex 34 was isolated in ca. 10% yield
upon subsequent separation of the components of the mixture
based on their different solubilities and characterized by IR,
(14) (a) Guedes da Silva, M. F. C.; Ferreira, C. M. P.; Frau´sto da Silva,
J. J. R.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans. 1998, 4139–4145.
(b) Kuznetsov, M. L.; Pombeiro, A. J. L. Dalton Trans. 2003, 738–747.
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A. J. L. Eur. J. Inorg. Chem. 2007, 1556–1565. (d) Smolenski, P.; Dinoi,
C.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L. J. Organomet. Chem.,in
press.
1
ESI-MS, and H NMR (see Experimental Section). When a
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A. J. L. J. Organomet. Chem. 1996, 511, 163–169. (b) Guedes da Silva,
M. F. C.; Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L.; Pellinghelli, M. A.;
Tiripicchio, A. J. Chem. Soc., Dalton Trans. 1996, 2763–2772. (c) Carvalho,
M. F. N. N.; Duarte, M. T.; Galva˜o, A. M.; Pombeiro, A. J. L.; Henderson,
R.; Fuess, H.; Svoboda, I. J. Organomet. Chem. 1999, 583, 56–62. (d)
Carvalho, M. F. N. N.; Galva˜o, A. M.; Pombeiro, A. J. L. J. Chem. Soc.,
Dalton Trans. 2000, 3393–3400.
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181, 147–175. (b) Kukushkin, V. Yu.; Tudela, D.; Pombeiro, A. J. L. Coord.
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631-637.
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Konovalov, V. E.; Kirakosyan, G. A. Inorg. Chem. 1992, 31, 3836–3840.
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A. I. Inorg. Chem. 1996, 35, 4926–4931.
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1771. (b) Pombeiro, A. J. L.; Kukushkin, V. Yu. Reactions of Coordinated
Nitriles. In ComprehensiVe Coordination Chemistry, 2nd ed.; Lever,
A. B. P., Ed.; Elsevier: New York, 2004; Vol. 1, Chapter 1.34, pp 639-
660.
chloroform solution of 34 was refluxed for ca. 2 h, no formation
of 22 was achieved, and only an insignificant thermal degrada-
tion of 34 was observed. Reflux of a chloroform solution of a
previously isolated and redissolved 22 for ca. 2 h results in its
slow thermal degradation, affording a broad mixture of products
(four spots on TLC), where minor quantities of 34 were detected.
For details of the reactions between the other complexes cis-
(19) (a) Luzyanin, K. V.; Kukushkin, V. Yu.; Kuznetsov, M. L.;
Garnovskii, D. A.; Haukka, M.; Pombeiro, A. J. L. Inorg. Chem. 2002, 41,
2981–2986. (b) Guedes da Silva, M. F. C.; Frau´sto da Silva, J. J. R.;
Pombeiro, A. J. L. Inorg. Chem. 2002, 41, 219–228. (c) Kopylovich, M. N.;
Pombeiro, A. J. L.; Fischer, A.; Kloo, L.; Kukushkin, V. Yu. Inorg. Chem.
2003, 42, 7239–7248. (d) Kopylovich, M. N.; Kukushkin, V. Yu.; Haukka,
M.; Luzyanin, K. V.; Pombeiro, A. J. L. J. Am. Chem. Soc. 2004, 126,
15040–15041. (e) Luzyanin, K. V.; Kukushkin, V. Yu.; Ryabov, A. D.;
Haukka, M.; Pombeiro, A. J. L. Inorg. Chem. 2005, 44, 2944–2953. (f)
Luzyanin, K. V.; Kukushkin, V. Yu.; Kuznetsov, M. L.; Ryabov, A. D.;
Galanski, M.; Haukka, M.; Tretyakov, E. V.; Ovcharenko, V. I.; Kopylovich,
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5382 Organometallics, Vol. 27, No. 20, 2008
Scheme 3. Interplay between cis-[MCl2(Ct NBut)2] (M ) Pd, Pt) and 7 at 20-25 °C
Luzyanin et al.
Scheme 4. Reaction of Iminoisoindolin-1-ones with an Isonitrile in cis-[MCl2(Ct NR)2]
for the PdII complexes) to moderate (60-65% for the PtII
species) isolated yields.
Table 1
M(CNR) iminoisoindolin-
M(CNR) iminoisoindolin-
species
1-one
product species
1-one
product
For the reaction under reflux conditions, the influences of
the ratio of the reagents and reaction time on the yields and
purity of the coupling products were studied (see Appendix 2,
Supporting Information, for the detailed studies). Thus, for the
reaction of palladium(II) complex 1 with 7, the best results were
obtained for the 1:1 molar ratio; the change to 1:2 or 1:4 ratios
did not significantly affect the reaction, but the coupling product
10 was strongly contaminated with 7 (ESI+-MS, m/z 146) and
7 · HCl (ESI+-MS, m/z 182). In the case of 1:2 or 1:4 molar
ratios, the increase of the reaction time from 4 to 24 h provides
a mixture of 10 with unreacted 7, 7 · hydrochloride, phthalimide
(which originates from the hydrolytic decomposition of 7 (ESI+-
MS, m/z 147; 1H NMR in CDCl3, δ 7.84 (s, 4H), 11.35 (s, 1H);
lit.26 7.85 (s, 4H), 11.38 (s, 1H)), and some other yet unidentified
byproducts.
1
7
8
9
7
8
9
7
8
9
10
11
12
13
14
15
16
17
18
4
5
6
7
8
9
7
8
9
7
8
9
19
20
21
22
23
24
25
26
27
2
3
[MCl2(Ct NR)2] (1, 3, 4, and 6) and iminoisoindolin-1-ones
(7-9) see Appendix 1, Supporting Information.
In order to increase the reactivity of the isonitrile ligands and/
or the solubility of the iminoisoindolin-1-ones, the reactions
were performed in CHCl3 under reflux conditions to achieve
higher yields of 10-27. Thus, the reaction between a metal-
bound isonitrile in cis-[MCl2(C′NR)2] (1-6) and the iminoisoin-
dolin-1-ones (7-9) proceeds in CHCl3 under reflux for 2 h
(Scheme 4), and the subsequent workup provides the carbene
species [MCl{C(NdC(C6R1R2R3R4CON))dN(H)R}(Ct NR)]
(M ) Pd, 10-18; M ) Pt, 19-27; Table 1) in good (80-85%
For the reaction of PtII-bound isonitriles in 6 with 7, the best
results were obtained with a 1:2 ratio. Similarly to the
palladium(II) complex, the change of the molar ratio of the
reagents to 1:4 does not significantly affect the reaction, but
affords 27 contaminated with 7 and some decomposition species.

Palladium and Platinum Iminocarbene Species
Organometallics, Vol. 27, No. 20, 2008 5383
For 1:2 or 1:4 molar ratios, the increase of the reaction time to
24 h results in the slow thermal decomposition of 27 and,
consequently, in a decrease of its isolated yield from 60% to
45%.
(for 10-12, 15, 17, and 20-25), or four (for 16) bands between
1738 and 1607 cm-1 belong to the overlapped ν(CdO) and
ν(CdN) vibrations from the iminoisoindolin-1-one moiety. The
medium intensity/weak bands in the range 3032-2989 cm-1
are characteristic of νs(C-H) and νas(C-H) vibrations.
In general, the addition of the iminoisoindolin-1-ones along
the Ct N triple bond of isonitrile proceeds at a higher degree
of selectivity in the case of the palladium(II) species as
compared to the corresponding platinum(II) complexes. In the
The 1H NMR spectra of the carbene complexes 10-27
display a broad peak in the range δ 8.90-10.70 assigned to the
M-CcarbenedN(H)R proton. This value is typical for a NH
proton involved into an intramolecular hydrogen bonding, which
was also found in the solid state upon examination of the X-ray
structure of 10 (see below). In each of 10-12 and 19-21,
obtained from cis-[MCl2(Ct NCy)2], the characteristic signals
of the proton and carbon of the tertiary HC from the cyclohexyl
ring of the Ct NR ligand resonates at ca. 4.50 and 54.5 ppm,
correspondingly, while in the carbene species the relevant signals
appear at a higher field (ca. 4.00 and 53.5 ppm, respectively).
Addition of the iminoisoindolin-1-one to the coordinated
isonitrile is accompanied by a pronounced δ 13C shift to lower
field of the quaternary C atom of one isonitrile to the carbene
(Ct N to CdN). Thus, in 10-27, the CcarbenedNH 13C signals
were found to resonate at ca. 200 ppm, i.e., approximately 80
ppm to lower field in comparison with the starting (isonitrile)MII
complexes (e.g., 115 ppm for Ct N in cis-[PdCl2(Ct NC6H11)2]).
In the 13C{1H} spectra of 13-15 obtained from cis-
[PdCl2(Ct NBut)2], a peak at ca. 115 ppm was assigned to Ct N
from the unreacted isonitrile moiety, while in the other
1
latter case, some byproducts were identified by H NMR and
ESI-MS, viz. phthalimide, derived from the hydrolysis of the
starting 3-iminoisoindolin-1-one, and previously unknown plati-
num iminoisoindolin-1-one complexes (34), among other uni-
dentified species.
One should mention that the coupling reaction proceeds in a
rather efficient way with the isonitriles bearing either alkyl or
aryl R groups and also with nonsubstituted (7) and substituted
(8 and 9) iminoisoindolin-1-ones. Furthermore, the addition of
the iminoisoindolin-1-one has a metal-mediated character.
Indeed, in a blank experiment conducted in CDCl3 at 50 °C, no
reaction between the metal-free isonitriles and 3-iminoisoindo-
lin-1-one was observed for 1 day.
The comparison of the integration between iminoisoindolin-
1-ones (7-9) and metal-bound organonitriles RCt N (see refs
22 and 23) versus 7-9 and coordinated isonitriles RNt C (this
work) points out that, in both cases, the interplay leads to
chelated species due to the complexation of the auxiliary amide
functionality of the iminoisoindolin-1-ones to yield six- and five-
membered metallacycles, respectively (Figure 1). However, the
isonitrile-based system affords solely monoiminocarbene com-
plexes, while the second RNt C ligand remains intact probably
due to the deactivation of the second isonitrile species in cis-
[MCl2(Ct NR)2] after the nucleophilic addition to the first
isonitrile ligand. Unlikely, the coupling between iminoisoindo-
lin-1-ones and metal-bound organonitriles RCN produces (1,3,5-
(20) (a) Wagner, G.; Pombeiro, A. J. L.; Kukushkin, V.Yu. J. Am. Chem.
Soc. 2000, 122, 3106–3111. (b) Wagner, G.; Haukka, M.; Frau´sto da Silva,
J. J. R.; Pombeiro, A. J. L.; Kukushkin, V. Yu. Inorg. Chem. 2001, 40,
264–271. (c) Belluco, U.; Benetollo, F.; Bertani, R.; Bombieri, G.; Michelin,
R. A.; Mozzon, M.; Tonon, O.; Pombeiro, A. J. L.; Guedes da Silva, M. F. C.
Inorg. Chim. Acta 2002, 334, 437–447. (d) Bokach, N. A.; Khripoun, A. V.;
Kukushkin, V. Yu.; Haukka, M.; Pombeiro, A. J. L. Inorg. Chem. 2003,
42, 896–903. (e) Kuznetsov, M. L.; Nazarov, A. A.; Pombeiro, A. J. L. J.
Phys. Chem. A 2005, 109, 8187–8198. (f) Makarycheva-Mikhailova, A. V.;
Golenetskaya, J. A.; Bokach, N. A.; Balova, I. A.; Haukka, M.; Kukushkin,
V. Yu. Inorg. Chem. 2007, 46, 8323–8331. (g) Lasri, J.; Charmier, M. A. J.;
Haukka, M.; Pombeiro, A. J. L. J. Org. Chem. 2007, 72, 750–755.
(21) (a) Guedes da Silva, M. F. C.; Hitchcock, P. B.; Hughes, D. L.;
Marjani, K.; Pombeiro, A. J. L.; Richards, R. L. J. Chem. Soc., Dalton
Trans. 1997, 3725–3731. (b) Tong, Y.-Y.; Frau´sto da Silva, J. J. R.;
Pombeiro, A. J. L.; Wagner, G.; Herrmann, R. J. Organomet. Chem. 1998,
552, 17–21. (c) Costa, M. T. A. R. S.; Dilworth, J. R.; Duarte, M. T.; Frau´sto
da Silva, J. J. R.; Galva˜o, A. M.; Pombeiro, A. J. L. J. Chem. Soc., Dalton
Trans. 1998, 2405–2410. (d) Almeida, S. S. P. R.; Guedes da Silva, M. F. C.;
Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L. J. Chem. Soc., Dalton Trans.
1999, 467–472. (e) Zhang, L.; Gamasa, M. P.; Gimeno, J.; Carbajo, R. J.;
Lo´pez-Ortiz, F.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L. Eur. J. Inorg.
Chem. 2000, 341–350. (f) Guedes da Silva, M. F. C.; Lemos, M. A. N. D.
A.; Frau´sto da Silva, J. J. R.; Pombeiro, A. J. L.; Pellinghelli, M. A.;
Tiripicchio, A. J. Chem. Soc., Dalton Trans. 2000, 373–380.
triazapentadienato)[M] complexes (M ) NiII,22 CuII,23 PdII 27
)
with two equivalent 1,3,5-triazapentadienato ligands formally
derived from the coupling with two nitriles.22,23,27
Characterization of the Palladium and Platinum Car-
bene Complexes 10-27. Complexes 10-27 were characterized
by elemental analyses (C, H, N), ESI+-MS, IR, and 1D (1H,
13C{1H}) and 2D (1H,1H-COSY, 1H,13C-HMQC/1H,13C-HSQC,
1H,13C-HMBC) NMR spectroscopies. In addition, the structures
of complexes 10 and 27 were elucidated by single-crystal X-ray
diffraction studies.
Complexes 10-27 gave satisfactory C, H, and N elemental
analyses, which are consistent with the proposed formulations
of the mixed (isonitrile/carbene)PdII or (isonitrile/carbene)PtII
complexes [MCl{C(NdC(C6R1R2R3R4CON))dN(H)R}(Ct
NR)], obtained via nucleophilic addition of the iminoisoindoli-
none to one isonitrile ligand and chelation of the newly formed
species. The ESI+-MS mass spectra of 10-27 display molecular
ion peaks and/or a fragmentation corresponding to the loss of
Cl’s from the molecular ion, viz. [M - nCl]+.
(22) (a) Gushchin, P. V.; Luzyanin, K. V.; Kopylovich, M. N.; Haukka,
M.; Pombeiro, A. J. L.; Kukushkin, V. Yu. Inorg. Chem. 2008, 47, 3088–
3094. (b) Kopylovich, M. N.; Haukka, M.; Kirillov, A. M.; Kukushkin, V.
Yu.; Pombeiro, A. J. L. Chem.-Eur. J. 2007, 13, 786–791.
(23) Kopylovich, M. N.; Luzyanin, K. V.; Haukka, M.; Pombeiro,
A. J. L.; Kukushkin, V. Yu., Dalton Trans. 2008, in press (doi: 10.1039/
b805243c).
(24) (a) Michelin, R. A.; Zanotto, L.; Braga, D.; Sabatino, P.; Angelici,
R. J. Inorg. Chem. 1988, 27, 85–92. (b) Michelin, R. A.; Zanotto, L.; Braga,
D.; Sabatino, P.; Angelici, R. J. Inorg. Chem. 1988, 27, 93–99. (c) Bertani,
R.; Mozzon, M.; Michelin, R. A. Inorg. Chem. 1988, 27, 2809. (d) Bertani,
R.; Mozzon, M.; Michelin, R. A.; Benetollo, F.; Bombieri, G.; Castilho,
T. J.; Pombeiro, A. J. L. Inorg. Chim. Acta 1991, 189, 175–187.
(25) (a) Luzyanin, K. V.; Kukushkin, V. Yu.; Kopylovich, M. N.;
Nazarov, A. A.; Galanski, M.; Pombeiro, A. J. L. AdV. Synth. Catal. 2008,
350, 135–142. (b) Pombeiro, A. J. L.; Luzyanin, K. V.; KukushkinV. Yu.;
KopylovichM. N. Patent PT-103718, Apr. 13, 2007.
The IR spectra of 10-27 exhibit one strong ν(Ct N)
stretching vibration in the range between 2220 and 2198 cm-1
,
while the starting cis-[MCl2(Ct NR)2] (M ) Pd, Pt) complexes
usually display two overlapped stretches in the interval
2250-2150 cm-1 28
This suggests the presence of only one
.
isonitrile ligand in the product of the reaction between cis-
[MCl2(Ct NR)2] and an iminoisoindolin-1-one. In the newly
formed CdN(H)R carbene moiety, ν(N-H) bands emerge in
the range 3256-3210 cm-1, while the corresponding very strong
bands due to ν(CdN) appear between 1561 and 1521 cm-1. In
the IR spectra of 10-27, two (for 13, 14, 18-20, and 27), three
(26) Pouchert, C. J. Aldrich Library of 13C and 1H FT-NMR Spectra;
Wiley: New York, 2008.
(27) Carvalho, R.; Gushchin, P. V.; Luzyanin, K. V.; Kopylovich, M. N.;
Haukka, M.; Pombeiro, A. J. L.; Kukushkin, V. Yu., unpublished results.
(28) Bonati, F.; Minghetti, G. J. Organomet. Chem. 1970, 24, 251–
256.

5384 Organometallics, Vol. 27, No. 20, 2008
Luzyanin et al.
Table 2. Crystal Data for 10, 27, and 30
[Pd(1)-C(9) 2.001(3) Å] distance in 10 is slightly longer, while
the Pt-Ccarbene [Pt(1)-C(9) 2.002(5) Å] in 27 is equal within
3σ to those reported for the related palladium and platinum
carbenecomplexescis-[PdCl2{C(OMe)dN(H)Me}2](1.953-1.972
Å),33 cis-[PdCl2{C(dNHCy)NHNHC(dNHCy)}2] (1.958-1.964
Å),34 [Pt{η2-(S,S′)-S2CdC(C(O)Me)}(CNBut){C(NEt2)(NH-
But)}] [2.053(2) Å],35 and cis-[PtCl2{CNC6H3(2,6-Me2)}-
{C(NH2)N(H)C6H3(2,6-Me2)}] [1.983(7) Å].9 In both com-
plexes, the CcarbenedN(H)R moiety of the carbene ligand is
roughly planar, and the Ccarbene-N moiety [C(9)-N(3) in 10:
1.308(3) Å, in 27: 1.329(7) Å] has a double-bond character,
with the bond length in accord with those found in the related
carbene complexes above (1.29-1.33 Å).9,33-35
The C(18)-N(4) triple bond of the unreacted isonitrile ligand
[10: 1.140(3), 27: 1.163(6) Å] has a normal value for the triple
CN bond and is consistent with that observed in related isonitrile
palladium and platinum complexes, e.g., cis-[PdCl2(Ct NR)2],
R ) Cy (1.128-1.142 Å),36 But (1.108-1.149 Å),37 C6H3(2,6-
Me2)(1.145-1.156Å),38[PtCl{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3-
(2,6-Me2)}(Ph2CdNH)](Cl) [1.151(9) Å],9 and [Pt{η2-(S,S′)-
S2CdC{C(O)Me}2}{CNC6H3(2,6-Me2)}2] [1.152(3) Å].35 An
intramolecular hydrogen bond between the proton (H3) from
the carbene CcarbenedN(H)R moiety and the chloride ligand [10:
d(N-H) 0.83(3), d(N · · · Cl) 3.119(2), d(H · · · Cl) 2.52 Å,
(NHCl) 130(3)°; 27: d(N-H) 0.96(7), d(N · · · Cl) 3.122(4),
d(H · · · Cl) 2.329 Å, (NHCl) 139(6)°] can be recognized.
All other bond lengths in 10 and 27 have normal values and
they agree with those reported9,33-35 for related platinum(II)
and palladium(II) carbene and isonitrile complexes.
10
27
30
empirical formula C22H27ClN4OPd C26H21Cl3N4OPt C56H44ClN10O8Pt2
fw
temp (K)
λ (Å)
cryst syst
space group
a (Å)
505.33
120(2)
0.71073
triclinic
j
P1
706.91
120(2)
0.71073
triclinic
j
P1
1410.64
120(2)
0.71073
monoclinic
C2/c
8.9322(3)
11.5556(5)
11.6712(5)
109.128(2)
107.747(2)
93.895(3)
1064.97(7)
2
8.3009(3)
12.4324(6)
12.7236(7)
74.722(3)
77.042(3)
85.816(3)
1234.28(10)
2
21.9505(5)
17.3228(5)
15.5420(4)
90
113.9340(10)
90
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
Z
5401.6(2)
4
Fcalc (Mg/m3)
1.576
1.902
1.735
µ(Mo KR) (mm-1) 1.018
6.037
16 007
5610
0.0621
0.0391
0.0649
5.288
39 169
6152
0.0458
0.0384
0.0838
reflns collected
unique reflns
Rint.
19 446
4493
0.0530
0.0318
0.0631
R1a (I g 2σ)
wR2b (I g 2σ)
2
2 2
a R1 ) ∑|Fo| - |Fc|/∑|Fo|. b wR2 ) [∑[w(Fo - Fc ) ]/∑[w(Fo2)2]]1/2
.
complexes the corresponding peak was not observed due to its
low intensity.
The 1H and 13C signal assignments were performed by
interpretation of gradient-enhanced two-dimensional 1H,13C-
1
HMQC/1H,13C-HSQC and H,13C-HMBC NMR spectra. Es-
2
pecially the long-range shift correlation experiments via JH,C
and 3JH,C coupling were found to be of high value because they
distinguished the signals of the newly formed carbene species
from CdO and CdN of the iminoisoindolin-1-one moiety. Thus,
Coupling of an Isonitrile in cis-[PtCl2(Ct NC6H4OMe-
4)2] and 3-Iminoisoindolin-1-one. We also attempted to employ
for our studies the platinum(II) complex bearing the aromatic
isonitrile Ct NC6H4OMe-4, viz. cis-[PtCl2(Ct NC6H4OMe-4)2]
(28), but in this particular case the interaction proceeds with a
very low selectivity. Thus, refluxing for ca. 4 h a mixture of 28
and 7 in CHCl3 in a 1:2 molar ratio of the reactants leads to a
broad mixture of PtII-containing species, which are difficult to
separate even by TLC, where more than five spots were detected.
However, among the products we succeeded in identifying the
1
in the low-field region (150-200 ppm) of the H,13C-HMBC
NMR spectrum of 12 (Supporting Information, Figure S1), the
13C signals of the imine and carbonyl carbons from the
iminoisoindolin-1-one moiety were detected at 171.4 and 184.0
ppm, correspondingly, and assigned through the shift correlation
peaks with the corresponding protons from the phenyl ring. A
signal resonating at 197.9 ppm displays no cross-coupling with
the phenyl protons, thus being assigned to the carbene carbon
atom (Ccarbene).
1
expected monoadduct 29 (yield is ca. 25%, based on the H
The crystallographic data and processing parameters for 10
and 27 are summarized in Table 2, while the corresponding
plots can be found in Figure 2, and bond lengths and angles
are given in Table 3.
NMR integration), the unusual type binuclear complex 30,
containing the deprotonated 3-iminoisoindolin-1-one, which
bridges two platinum centers, and complex 31 (ESI+-MS, m/z
751 [M]+; IR, cm-1 2196 ν(Ct N)). Complex 31 at least
formally results from the replacement of the chloride ligand in
29 by the deprotonated iminoisoindolin-1-one (Scheme 5).
When the reaction of 28 and 7 in CHCl3 was performed at
20-25 °C for 4 h, monitoring of the reaction mixture by TLC
shows that it contains at least three products, which are different
from 29-31. ESI-MS monitoring indicated the presence of
[PtCl(C6H4CONCNH)(Ct NC6H4OMe-4)2] (32) (m/z 641 [M]),
derived from the substitution of a chloride in 28 for a
monodeprotonated 7, while the absence of the characteristic
The crystal structure of either 10 or 27 consists of discrete
molecules and metal centers adopt a distorted square-planar
geometry. The unreacted isonitrile is in the trans position to
the carbene carbon atom of {C(NdC(C6R1R2R3R4CON))d
N(H)R}, which acts as a bidentate ligand, forming the five-
membered chelate ring. In the metallacycle, the angles
N(1)-Pd(1)-C(9) and N(1)-Pt(1)-C(9) are 77.55(18)° and
78.09(10)°, being slightly smaller than that previously observed
in the related palladium and platinum five-membered chelates
[Pd(phen){C(dO)NPhC(dO)NPh}](80.14Å),29[PdI{Ct NC6H3(2,6-
Me2)}{C(C6H4(2-NH2))dNC6H3(2,6-Me2)}] (82.89 Å),30 cis-
[PtCl(NH3)(NH2CH2COO)] (81.56 Å),31 or [PtCl(PPh3)(NMe2-
CH2NMe2CH2)](Cl) (82.30 Å).32 The carbene ligands in both
10 and 27 are in the E-configuration, and the Pd-Ccarbene
(32) Barefield, E. K.; Carrier, A. M.; Sepelak, D. J.; Van Derveer, D. G.
Organometallics 1982, 1, 103–110.
(33) Domiano, P.; Musatti, A.; Nardelli, M.; Predieri, G. J. Chem. Soc.,
Dalton Trans. 1975, 2165–2168.
(34) Moncada, A. I.; Khan, M. A.; Slaughter, L. M. Tetrahedron Lett.
2005, 46, 1399–1403.
(29) Paul, F.; Fischer, J.; Ochsenbein, P.; Osborn, J. A. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 1638–1640.
(30) Vicente, J.; Abad, J.-A.; Frankland, A. D.; Lopez-Serrano, J.; De
Arellano, M. C. R.; Jones, P. G. Organometallics 2002, 21, 272–282.
(31) Baidina, I. A.; Podberezskaya, N. V.; Krylova, L. F.; Borisov, S. V.;
Bakakin, V. V. Zh. Strukt. Khim. (Russ. J. Struct. Chem.) 1980, 21, 106–
110.
(35) Vicente, J.; Chicote, M. T.; Huertas, S. Inorg. Chem. 2003, 42,
4268–4274.
(36) Kitano, Y.; Hori, T. Acta Crystallogr. B 1981, 37, 1919–1921.
(37) Perreaul, D.; Drouin, M.; Michel, A.; Harvey, P. D. Inorg. Chem.
1993, 32, 1903–1912.
(38) Drouin, M.; Perreaul, D.; Harvey, P. D.; Michel, A. Acta Crystal-
logr. C 1991, 47, 752–754.

Palladium and Platinum Iminocarbene Species
Organometallics, Vol. 27, No. 20, 2008 5385
Figure 2. View of 10 (left) and 27 (right) with atomic numbering schemes. Thermal ellipsoids are drawn with 50% probability.
Table 3. Selected Bond Lengths [Å] and Angles [deg] for 10 and 27
coordination environment, viz. one C(NdC(C6H4CON))dN(H)-
(C6H4OMe-4) ligand coordinated by both the carbene C atom
and the N(2) atom from the deprotonated iminoisoindolin-1-
one moiety, and one isonitrile ligand. The fourth coordination
site at each PtII center is occupied by one of the two nitrogens
from the deprotonated 3-iminoisoindolin-1-one, which bridges
the two platinum centers. The Pt · · · Pt separation is ca. 3.1485(4)
Å, suggesting that in 30 · H2O there is no real Pt-Pt bond. One
should mention that the structure of 30 · H2O represents the first
crystallographic evidence for metal complexes bearing any
coordinated iminoisoindolin-1-one.
In 30 · H2O, the unreacted isonitrile ligand is located in the
trans position to N(2) from the iminoisoindolin-1-one func-
tionality of the carbene. The latter ligand forms a five-membered
metallacycle, with the N(1)-Pt(1)-C(9) angle [78.2(2)°] slightly
smaller than in previously characterized relevant platinum five-
membered chelates, e.g. [PtCl2(2,2′-bpy)] (79.06-80.80 Å),39
cis-[PtCl(NH3)(NH2CH2COO)] (81.56 Å),31 or [PtCl(NMe2-
CH2NMe2CH2)(PPh3)](Cl) (82.30 Å).32 The carbene ligand is
in the Z-configuration, and both Pt-Ccarbene [Pt(1)-C(9) 1.999(6)
Å] and Ccarbene-N [C(9)-N(3) 1.322(7) Å] distances are in good
agreement with those previously observed in the related platinum
carbene complexes [PtCl{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3-
(2,6-Me2)}(Ph2CdNH)](Cl) [1.995(6) and 1.330(8) Å]9 and
[PtCl2{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3(2,6-Me2)}][1.983(7)
and 1.295(8) Å].9 The C(17)-N(4) multiple bond length of the
isonitrile [1.149(7) Å] has a normal value for the triple CN bond
and is consistent with those reported for related isonitrile
platinum complexes, e.g., [PtCl{CNC6H3(2,6-Me2)}{C(NH2)N(H)-
C6H3(2,6-Me2)}(Ph2CdNH)]Cl [1.151(9) Å]9 and [Pt{η2-(S,S′)-
S2CdC{C(O)Me}2}{CNC6H3(2,6-Me2)}2] [1.152(3) Å].35
The identification of 30 and 31 allows the understanding of
the lower selectivity for the PtII-mediated addition of 3-imi-
noisoindolin-1-one to isonitrile as compared to the PdII system.
Thus, in the case of platinum, the integration of 7 and the ligated
10
27
Pd(1)-N(1)
2.000(2)
Pt(1)-N(1)
1.994(4)
2.002(5)
1.983(5)
Pd(1)-C(9)
Pt(1)-C(9)
2.001(3)
2.044(3)
2.3256(7)
Pd(1)-C(18)
Pt(1)-C(18)
Pd(1)-Cl(1)
Pt(1)-Cl(1)
2.3157(14)
1.216(6)
1.363(6)
1.381(7)
1.310(6)
1.392(6)
1.329(7)
1.453(6)
1.163(6)
1.402(6)
O(1)-C(1)
1.217(3)
1.370(3)
1.394(3)
1.313(3)
1.381(3)
1.308(3)
1.484(3)
1.140(3)
1.461(3)
78.09(10)
N(1)-C(8)
N(1)-C(1)
N(2)-C(8)
N(2)-C(9)
N(3)-C(9)
N(3)-C(10)
N(4)-C(18)
N(4)-C(19)
N(1)-Pd(1)-C(9)
N(1)-Pt(1)-C(9)
C(18)-Pd(1)-Cl(1)
C(18)-Pt(1)-Cl(1)
C(8)-N(2)-C(9)
C(18)-N(4)-C(19)
N(3)-C(9)-N(2)
C(9)-N(3)-C(10)
77.55(18)
93.74(8)
90.01(15)
108.8(4)
173.9(5)
118.2(4)
124.4(4)
109.5(2)
174.6(3)
117.2(2)
126.9(2)
signals (viz. the carbene NH and the CdN group in the 1H and
13C{1H} NMR spectra, correspondingly) clearly demonstrated
that no addition of 7 to 28 giving 29 occurred. Our attempts to
promote the selectivity of the process by decreasing the reaction
temperature to -20 °C were not successful because even at this
low temperature the interplay still gave a mixture having a
composition similar to that obtained at 20-25 °C.
The identification of 29-32 was based on ESI+-MS (1357
[M30 - Cl]; 751 [M31]; 641 [M29]) and NMR spectra [1H NMR
(CDCl3, δ) for 31: 10.02 (s, br, 1H, NH), 7.80-7.68 (m, 4H)
(aryls from the isoindolin-1-one moiety), 7.25-7.14 (m, 6H,
aryls), 3.85 (s, 3H), and 3.83 (s, 3H, OMe)]. In addition, slow
evaporation of the reaction mixture resulted in the release of
crystals of 30 · H2O suitable for an X-ray diffraction study
(Figure 3); our attempts to isolate pure 29 and 31 from the
reaction mixture were not successful insofar as they are strongly
contaminated with other products.
(39) (a) Osborn, R. S.; Rogers, D. J. Chem. Soc., Dalton Trans. 1974,
1002–1004. (b) Textor, M.; Oswald, H. R. Z. Anorg. Allg. Chem. 1974,
407, 244–256. (c) Canty, A. J.; Skelton, B. W.; Traill, P. R.; White, A. H.
Aust. J. Chem. 1992, 45, 417–422. (d) Connick, W. B.; Henling, L. M.;
Marsh, R. E.; Gray, H. B. Inorg. Chem. 1996, 35, 6261–6265. (e) Falvello,
L. R.; Garde, R.; Miqueleiz, E. M.; Tomas, M.; Urriolabeitia, E. P. Inorg.
Chim. Acta 1997, 264, 297–303. (f) Grzesiak, A. L.; Matzger, A. J. Inorg.
Chem. 2007, 46, 453–457.
In the crystal structure of 30 · H2O, both PtII centers exhibit
a slightly distorted square-planar geometry. They have the same

5386 Organometallics, Vol. 27, No. 20, 2008
Scheme 5. Reaction of the 3-Iminoisoindolin-1-one with cis-[PtCl2(Ct NR)2] (R ) C6H4OMe-p)
Luzyanin et al.
Ct NR to furnish the carbene species occurs concurrently with
the replacement of the chlorides from the starting material,
forming rather inert substitution products, which are thus
removed from further coupling.
Thus, we have demonstrated that the reaction between one
isonitrile in cis-[MCl2(Ct NR)] (M ) PdII, PtII) and an
iminoisoindolin-1-one opens up a route to palladium and
platinum complexes containing iminocarbene ligands of a novel
type (see Scheme 3) derived from a metal-mediated nucleophilic
attack by the sp2-N nucleophilic center of the iminoisoindolin-
1-one on the CN moiety of the coordinated RNt C. The
coupling proceeds with a higher selectivity in the case of the
PdII species as compared to the corresponding PtII complexes,
Final Remarks
This paper reports on the first unequivocally confirmed
example of a metal-mediated integration between an imine and
an isonitrile affording chelate-stabilized iminocarbene species.
Figure 3. Thermal ellipsoid view of 30 with atomic numbering scheme. Thermal ellipsoids are drawn with 50% probability. The bridging
ligand is highly disordered, and the similar coordination environment for the second platinum atom is not shown. Selected bond lengths [Å]
and angles [deg] for 30: Pt(1)-C(17) 1.923(6), Pt(1)-C(9) 1.999(6), Pt(1)-N(1) 2.020(4), Pt(1)-N(5) 2.076(5), Pt(1)-Pt(1)#1 3.1485(4),
N(2)-C(9) 1.385(7), N(3)-C(9) 1.322(7), N(3)-C(10) 1.417(7), N(4)-C(17) 1.149(7), N(4)-C(18) 1.403(8), C(17)-Pt(1)-C(9) 101.3(2),
C(9)-Pt(1)-N(1) 78.2(2), C(17)-Pt(1)-N(5) 86.9(2), N(1)-Pt(1)-N(5) 93.14(18), C(9)-N(3)-C(10) 126.6(5), C(17)-N(4)-C(18)
174.7(6), N(3)-C(9)-N(2) 111.7(5), N(4)-C(17)-Pt(1) 169.7(5).

Palladium and Platinum Iminocarbene Species
Organometallics, Vol. 27, No. 20, 2008 5387
and were constrained to ride on their parent atoms, with N-H )
0.88 Å, Uiso ) 1.2Ueq(parent atom), C · · · H ) 0.95-1.00 Å, and
Uiso ) (1.2-1.5)Ueq(parent atom). The crystallographic data are
summarized in Table 2, and selected bond lengths and angles in
Table 3.
presumably due to (i) a stronger activation of the isocyanide
by a PdII center as compared to the PtII center on account of
the higher charge density on the former metal center (see ref
18 for examples), and (ii) a different balance between kinetic
lability and thermodynamic stability for the PdII and PtII species.
Further studies directed to widening the family of metal
heteroatom-stabilized carbenes derived from the addition of
various imine nucleophiles to metal-bound isonitriles are
currently under way in our group with particular emphasis on
the aliphatic AlkNt C species, which are substantially less
activated toward the coupling than the aromatic isonitriles
ArNt C.
Synthetic Work. Reaction of cis-[MCl2(Ct NR)2] (M ) Pt,
Pd; R ) Cy, But, C6H3(2,6-Me2)) and 3-Iminoisoindolin-1-one
[or 5-methyl-3-iminoisoindolin-1-one, or 5,6-dichloro-3-imi-
noisoindolin-1-one]. A suspension of the corresponding imi-
noisoindolin-1-one (7-9) (0.2 mmol) in CHCl3 (2 mL) was added
to a solution of cis-[MCl2(RNC)2] (M ) Pd, 0.2 mmol; M ) Pt,
0.1 mmol) in CHCl3 (5 mL). The reaction mixture was then refluxed
for 2 h. During the reaction time, the color of the mixture turned
from yellow to bright yellow-green (in the case of 1-3) or to
yellow-orange (in the case of 4-6). After 2 h, the reaction mixture
was evaporated at 20-25 °C to dryness under a stream of nitrogen,
and the solid residue was extracted with two 5 mL portions of
CHCl3 (five 5 mL portions for the reactions with 9). The bright
yellow solution was filtered off to remove some insoluble material,
and the filtrate was evaporated to dryness under a stream of nitrogen
at room temperature, washed with five 5 mL portions of Pri2O, 1
mL portion of cold (5 °C) Et2O, and again with five 5 mL portions
of Pri2O, and dried in Vacuo at 20-25 °C. Yields range from 80%
to 85% for 10-18 and 60-65% for 19-27.
[PdCl{C0(NdC(C6H4CON))dN(H)Cy}(Ct NCy)] (10). Anal.
Calcd for C22H27N4ClOPd: C, 52.29; H, 5.39; N, 11.09. Found: C,
51.29; H, 5.61; N, 10.66. ESI+-MS, m/z: 469 [M - Cl - H]+. IR
(KBr, selected bands, cm-1): 3256 m ν(N-H); 2934 m, 2856 mw
ν(C-H); 2216 s ν(Ct N); 1722 s, 1685 m, 1622 s ν(CdO) +
ν(CdN); 1541 vs ν(CcarbenedN); 712 s δ(C-H from aryls). 1H
NMR (CDCl3, δ): 8.90 (s, br, 1H, NH), 7.85-7.52 (m, 4H, aryls),
4.52 (m, br, 1H, HCCy), 3.91 (m, br, 1H, HCCy), 1.99-1.64 and
1.44-1.40 (m, 20H, Cy). 13C{1H} NMR (CDCl3, δ): 198.4
(CcarbenedN), 186.2 (CdO), 173.7 (CdN), 136.1, 133.9, 133.3,
132.2, 124.0, 123.2 (aryls), 54.5 (HCCy), 53.5 (HCCy), 32.5, 32.1,
25.3, 24.9, 24.4, 23.0 (Cy). Crystals of 10 suitable for single-crystal
X-ray diffraction study were obtained upon slow evaporation of
10:1 (v/v) acetone-toluene solutions of 10 in air at ca. 20-25 °C.
Experimental Section
Materials and Instrumentation. Solvents, PdCl2, K2[PtCl4], and
all isonitriles were obtained from commercial sources and used as
received apart from chloroform, which was purified by conventional
distillation over calcium chloride. The complexes cis-[PdCl2(RNC)2]
(R ) Cy 1, But 2, C6H3(2,6-Me2) 3),24 cis-[PtCl2(RNC)2] (R ) Cy
4, But 5, C6H3(2,6-Me2) 6, C6H4OMe-4 28),24,28 3-iminoisoidolin-
1-one 7,25 and its substituted derivatives (R1, R3, R4 ) H, R2 )
Me/R1, R2, R4 ) H, R3 ) Me 8 (isomeric mixture); R1, R4 ) H,
R2, R3 ) Cl 9)25 were prepared as previously reported. C, H, and
N elemental analyses were carried out by the Microanalytical
Service of the Instituto Superior Te´cnico. ESI+ mass spectra were
obtained on a Varian 500-MS LC ion trap mass spectrometer.
Infrared spectra (4000-400 cm-1) were recorded on a BIO-RAD
FTS 3000MX instrument in KBr pellets. 1D (1H, 13C{1H}) and
2D (1H,1H-COSY, 1H,13C-HMQC, 1H,13C-HSQC, and 1H,13C-
HMBC) NMR spectra were recorded on Bruker Avance II+ 300
and 400 MHz (UltraShield Magnet) and Bruker Avance II+ 500
MHz (UltraShield Plus Magnet) spectrometers at ambient temperature.
X-ray Structure Determinations. Crystals were immersed in
CryoOil, mounted in a nylon loop, and measured at a temperature
of 120 K. The single-crystal X-ray diffraction data were collected
by means of a Nonius KappaCCD diffractometer using Mo KR
radiation (λ ) 0.71073 Å). The DENZO/SCALEPACK40 program
package was used for cell refinement and data reduction. The
structures were solved by direct methods using the SHELXS-9741
or SIR9742 programs with WinGX43 graphical user interface. A
multiscan absorption correction based on equivalent reflections
(SADABS44 or SORTAV45) was applied to all the data. Structural
refinements were carried out using SHELXL-97.46 In 30 · H2O, the
bridging ligand and the counterion Cl- were disordered over two
positions with equal occupancies of 0.5. The bond lengths between
C33 and C34 as well as between C33 and C29#1 (#1 ) 1-x, +y,
1.5-z) in the disordered moiety were fixed to 1.390(1) Å. Also,
the aromatic hydrogen atoms in the disordered unit were omitted.
In 30 · H2O, the H2O hydrogen atoms were located from the
difference Fourier map but constrained to ride on their parent atom,
with Uiso ) 1.5Ueq(parent atom). In 10 and 27, the NH hydrogen
atoms were located from the difference Fourier map and refined
isotropically. Other hydrogen atoms were positioned geometrically
[PdCl{C(NdC(C6H3(Me)CON))dN(H)Cy}(Ct NCy)] (11).
Anal. Calcd for C23H29N4ClOPd: C, 53.19; H, 5.63; N, 10.79.
Found: C, 53.51; H, 5.61; N, 11.29. ESI+-MS, m/z: 521 [M]+. IR
(KBr, selected bands, cm-1): 3248 m ν(N-H); 2936 m, 2852 mw
ν(C-H); 2215 s ν(Ct N); 1728 s, 1678 m, 1616 s ν(CdO) +
ν(CdN); 1538 vs ν(CcarbenedN); 723 s δ(C-H from aryls). 1H
NMR (CDCl3, δ): 8.97 (s, br, 1H, NH), 7.65-7.51 (m, 4H, aryls),
4.57 (m, br, 1H, HCCy), 4.02 (m, br, 1H, HCCy), 2.45 (s, 3H,
Me), 1.97-1.62 and 1.55-1.41 (m, 20H, Cy). 13C{1H} NMR
(CDCl3, δ): 199.4 (CcarbenedN), 184.3 (CdO), 172.1 (CdN), 136.2,
135.1, 134.0, 133.9, 124.2, 123.1 (aryls), 54.4 (HCCy), 53.5
(HCCy), 32.1, 32.0, 25.35, 24.8, 24.2, 23.1 (Cy), 21.1 (Me).
[PdCl{C(NdC(C6H2(Cl2)CON))dN(H)Cy}(Ct NCy)] (12).
Anal. Calcd for C22H25N4Cl3OPd: C, 46.01; H, 4.39; N, 9.76. Found:
C, 46.08; H, 4.20; N, 9.80. ESI+-MS, m/z: 540 [M - Cl]+. IR
(KBr, selected bands, cm-1): 3256 m ν(N-H); 2934 m, 2856 mw
ν(C-H); 2216 s ν(Ct N); 1722 s, 1685 m, 1622 s ν(CdO) +
ν(CdN); 1541 vs ν(CcarbenedN); 712 s δ(C-H from aryls). 1H
NMR (CDCl3, δ): 8.99 (s, br, 1H, NH), 7.94 (s, 1H) and 7.82 (s,
1H) (aryls), 4.51 (m, br, 1H, HCCy), 3.93 (m, br, 1H, HCCy),
1.97-1.81 and 1.49-1.25 (m, 20H, Cy). 13C{1H} NMR (CDCl3,
δ): 197.5 (CcarbenedN), 184.0 (CdO), 171.4 (CdN), 137.8, 136.5,
135.4, 133.1, 125.6, 125.1 (aryls), 54.4 (HCCy), 53.6 (HCCy), 32.4,
31.9, 31.7, 24.2, 24.3, 22.7 (Cy).
(40) Otwinowski, Z.; Minor, W. Processing of X-ray Diffraction Data
Collected in Oscillation Mode. In Methods in Enzymology, Macromolecular
Crystallography, Part A; Carter, C. W., Jr., Sweet, R. M., Eds.; Academic
Press: New York, 1997; Vol. 276, pp 307-326.
(41) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure
Determination; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(42) Altomare, A.; Burla, M. C.; Camalli, M. C.; Giacovazzo, C.;
Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, R. J. Appl.
Crystallogr. 1999, 32, 115–119.
(43) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837–838.
(44) Sheldrick, G. M. SADABS, Bruker Nonius scaling and absorption
correction, v 2.10; Bruker AXS, Inc.: Madison, WI, 2003.
(45) Blessing, R. H. Acta Crystallogr., Sect. A 1995, A51, 33–38.
(46) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
[PdCl{C(NdC(C6H4CON))dN(H)But}(Ct NBut)] (13). Anal.
Calcd for C18H23N4ClOPd: C, 47.70; H, 5.11; N, 12.36. Found: C,
46.98; H, 5.11; N, 12.45. ESI+-MS, m/z: 455 [M]+. IR (KBr,
selected bands, cm-1): 3245 mw ν(N-H); 2981 m, 2934 mw
ν(C-H); 2212 s ν(Ct N); 1688 vs, 1627 m ν(CdO) + ν(CdN);

5388 Organometallics, Vol. 27, No. 20, 2008
Luzyanin et al.
1549 vs ν(CcarbenedN); 723 m δ(C-H from Ar). 1H NMR (CDCl3,
δ): 9.00 (s, br, 1H, NH), 7.84-7.76 (m, 4H, aryls), 1.57 (s, 9H)
and 1.53 (s, 9H, But). 13C{1H} NMR (CDCl3, δ): 200.1
(CcarbenedN), 174.0 (CdO), 165.1 (CdN), 133.7, 133.5, 133.4,
133.1, 132.5, 132.1, 124.0, 123.6, 123.0, 122.9, 121.9 (aryls), 60.1
and 57.7 (CMe3), 30.0 and 29.3 (CMe3).
[PtCl{C(NdC(C6H4CON))dN(H)Cy}(Ct NCy)] (19). Anal.
Calcd for C22H27N4ClOPt: C, 44.48; H, 4.58; N, 9.43. Found: C,
44.38; H, 4.61; N, 9.62. ESI+-MS, m/z: 595 [M]+. IR (KBr, selected
bands, cm-1): 3201 m ν(N-H); 2932 m, 2856 mw ν(C-H); 2223 s
ν(Ct N); 1726 s, 1610
s ν(CdO) + ν(CdN); 1546 vs
ν(CcarbenedN); 717 s δ(C-H from aryls). 1H NMR (CDCl3, δ):
8.97 (s, br, 1H, NH), 7.85-7.60 (m, 4H, aryls), 4.57 (m, br, 1H,
HCCy), 4.15 (m, br, 1H, HCCy), 2.02-1.62 and 1.47-1.42 (m,
20H, Cy). 13C{1H} NMR (CDCl3, δ): 192.7 (CcarbenedN), 186.2
(CdO), 169.7 (CdN), 136.0, 134.4, 133.6, 132.8, 124.5, 123.6
(aryls), 58.0 (HCCy), 55.6 (HCCy), 32.6, 32.2, 25.4, 25.1, 24.9,
24.7, 24.5, 23.0, 22.8 (Cy).
[PdCl{C(NdC(C6H3(Me)CON))dN(H)But}(Ct NBut)] (14).
Anal. Calcd for C19H25N4ClOPd: C, 48.83; H, 5.39; N, 11.99.
Found: C, 48.80; H, 5.37; N, 11.75. ESI+-MS, m/z: 491 [M + Na
- H]+. IR (KBr, selected bands, cm-1): 3240 mw ν(N-H);
2982 m, 2935 mw ν(C-H); 2214 s ν(Ct N); 1682 vs, 1617 m
ν(CdO) + ν(CdN); 1546 vs ν(CcarbenedN); 732 m δ(C-H from
1
Ar). H NMR (CDCl3, δ): 9.12 (s, br, 1H, NH), 7.94-7.58 (m,
[PtCl{C(NdC(C6H3(Me)CON))dN(H)Cy}(Ct NCy)] (20).
Anal. Calcd for C23H29N4ClOPt: C, 45.43; H, 4.81; N, 9.21. Found:
C, 45.82; H, 4.92; N, 9.18. ESI+-MS, m/z: 573 [M - Cl]+. IR
(KBr, selected bands, cm-1): 3215 m ν(N-H); 2931 m ν(C-H);
2229 s ν(Ct N); 1748 s, 1667 m, 1616 s ν(CdO) + ν(CdN); 1545
vs ν(CcarbenedN); 738 s δ(C-H from aryls). 1H NMR (CDCl3, δ):
9.06 (s, br, 1H, NH), 7.80-7.41 (m, 4H, aryls), 4.77 (m, br, 1H,
HCCy), 4.20 (m, br, 1H, HCCy), 2.51 and 2.46 (s, 3H, Me),
2.15-1.80 and 1.44-1.13 (m, 20H, Cy). 13C{1H} NMR (CDCl3,
δ): 194.4 (CcarbenedN), 184.2 (CdO), 167.3 (CdN), 145.9, 135.0,
134.5, 133.6, 130.1, 126.7, 126.1, 124.4, 124.1, 123.5 (aryls), 56.4
(HCCy), 55.5 (HCCy), 31.9, 29.6, 25.3, 24.6, 22.1, 13.0 (Cy), 22.9
(Me).
4H, aryls), 2.44 (s) and 2.38 (s, 3H, Me from the isoindolinone
moiety), 1.56 (s, 9H) and 1.55 (s, 9H, But). 13C{1H} NMR (CDCl3,
δ): 199.8 (CcarbenedN), 175.5 (CdO), 167.2 (CdN), 134.5, 132.4,
132.1, 132.0, 129.1, 124.6, 122.0, 121.7, 121.6 (aryls), 60.3 and
56.7 (CMe3), 21.2 and 21.0 (Me).
[PdCl{C(NdC(C6H2(Cl2)CON))dN(H)But}(Ct NBut)] (15).
Anal. Calcd for C18H21N4Cl3OPd: C, 41.40; H, 4.05; N, 10.73.
Found: C, 41.45; H, 4.28; N, 10.83. ESI+-MS, m/z: 546 [M + Na]+.
IR (KBr, selected bands, cm-1): 3229 mw ν(N-H); 2981 mw, 2935
mw, 2877 w ν(C-H); 2217 m ν(Ct N); 1717 m, 1675 mw, 1611 w
ν(CdO) + ν(CdN); 1561 vs ν(CcarbenedN); 731 s δ(C-H). 1H
NMR (CDCl3, δ): 9.04 (s, br, 1H, NH), 7.84 (s, 1H) and 7.79 (s,
1H) (aryls), 1.55 (s, 9H) and 1.52 (s, 9H, But). 13C{1H} NMR
(CDCl3, δ): 199.6 (CcarbenedN), 183.3 (CdO), 171.7 (CdN), 137.9,
136.6, 135.5, 133.4, 125.5, 125.2 (aryls), 115.1 (Ct N), 60.3 and
58.2 (CMe3), 30.0 and 29.4 (CMe3).
[PtCl{C(NdC(C6H2(Cl2)CON))dN(H)Cy}(Ct NCy)] (21).
Anal. Calcd for C22H25N4Cl3OPt: C, 39.86; H, 3.80; N, 8.45. Found:
C, 39.92; H, 3.79; N, 8.32. ESI+-MS, m/z: 651 [M - Cl + Na]+.
IR (KBr, selected bands, cm-1): 3246 m ν(N-H); 2932 m, 2852
mw ν(C-H); 2228 s ν(Ct N); 1732 s, 1681 m, 1618 s ν(CdO) +
ν(CdN); 1542 vs ν(CcarbenedN); 722 s δ(C-H from aryls). 1H
NMR (CDCl3, δ): 8.97 (s, br, 1H, NH), 7.92 (s, 1H) and 7.80 (s,
1H) (aryls), 4.41 (m, br, 1H, HCCy), 4.12 (m, br, 1H, HCCy),
2.02-1.79 and 1.42-1.12 (m, 20H, Cy). 13C{1H} NMR (CDCl3,
δ): 194.2 (CcarbenedN), 184.0 (CdO), 170.1 (CdN), 137.8, 133.2,
133.0, 126.4, 125.5, 125.2, 125.1 (aryls), 54.5 (HCCy), 53.2
(HCCy), 32.3, 31.8, 31.7, 31.5, 24.2, 24.3, 22.7 (Cy).
[PdCl{C(NdC(C6H4CON))dN(H)C6H3(2,6-Me2)}{Ct NC6H3-
(2,6-Me2)}] (16). Anal. Calcd for C26H23N4ClOPd: C, 56.84; H, 4.22;
N, 10.20. Found: C, 57.21; H, 4.28; N, 10.11. ESI+-MS, m/z: 551
[M]+. IR (KBr, selected bands, cm-1): 3217 mw ν(N-H); 2961
mw, 2951 mw ν(C-H); 2199 s ν(Ct N); 1727 vs, 1687 s, 1629 w,
1607 w ν(CdN) + ν(CdO); 1521 vs ν(CcarbenedN); 713 s δ(C-H
from Ar). 1H NMR (CDCl3, δ): 10.24 (s, br, 1H, NH), 7.75-7.70
(m, 4H) (aryls from isoindolinone moiety), 7.27-7.14 (m, 6H,
aryls), 2.61 (s, 6H) and 2.31 (s, 6H, Me). 13C{1H} NMR (CDCl3,
δ): 201.3 (CcarbenedN), 188.0 (CdO), 173.4 (CdN), 136.4, 135.7,
135.6, 134.0, 133.9, 133.4, 132.3, 130.0, 128.4, 128.3, 128.2, 128.0,
124.3, 123.2 (aryls), 18.9 and 18.8 (Me).
[PtCl{C(NdC(C6H4CON))dN(H)But}(Ct NBut)] (22). Anal.
Calcd for C18H23N4ClOPt: C, 39.89; H, 4.28; N, 10.34. Found: C,
39.98; H, 4.11; N, 10.45. ESI+-MS, m/z: 543 [M]+. IR (KBr,
selected bands, cm-1): 3240 mw ν(N-H); 2982 m ν(C-H); 2229 s
ν(Ct N); 1718 mw, 1674 vs, 1609 m ν(CdO) + ν(CdN); 1543
[PdCl{C(NdC(C6H3(Me)CON))dN(H)C6H3(2,6-Me2)}{Ct NC6-
H3(2,6-Me2)}] (17). Anal. Calcd for C27H25N4ClOPd: C, 57.56; H,
4.47; N, 9.94. Found: C, 57.46; H, 4.36; N, 8.55. ESI+-MS, m/z:
528 [M - Cl]+. IR (KBr, selected bands, cm-1): 3214 mw ν(N-H);
3032 mw, 2959 w, 2920 mw ν(C-H); 2198 s ν(Ct N); 1725 s,
1681 s, 1616 m ν(CdO) + ν(CdN); 1522 vs ν(CcarbenedN); 778
+ 723 s δ(C-H from Ar). 1H NMR (CDCl3, δ): 10.24 (s, br, 1H,
NH), 7.75-7.70 (m, 4H) (aryls from the isoindolinone moiety),
7.27-7.14 (m, 6H, aryls), 2.60 (s, 6H) and 2.31 (s, 6H, Me), 2.47
(s, 3H, Me from the isoindolinone moiety). 13C{1H} NMR (CDCl3,
δ): 199.9 (CcarbenedN), 187.2 (CdO), 168.9 (CdN), 136.6, 136.5,
136.4, 134.0, 131.1, 130.7, 128.4, 128.3, 128.2, 128.0 (aryls), 21.2
(Me from the isoindolinone moiety), 18.9 and 18.6 (Me).
1
vs ν(CcarbenedN); 707 m δ(C-H from Ar). H NMR (CDCl3, δ):
8.56 (s, br, 1H, NH), 7.83-7.41 (m, 4H, aryls), 1.61 (s, 9H) and
1.49 (s, 9H, But). 13C{1H} NMR (CDCl3, δ): 198.7 (CcarbenedN),
173.8 (CdO), 168.6 (CdN), 134.2, 133.6, 132.4, 124.0, 123.9,
123.5, 123.2 (aryls), 58.2 and 53.0 (CMe3), 30.0, 29.8 and 27.8
(CMe3).
[PtCl{C(NdC(C6H3(Me)CON))dN(H)But}(Ct NBut)] (23).
Anal. Calcd for C19H25N4ClOPt: C, 41.05; H, 4.53; N, 10.08. Found:
C, 41.01; H, 4.52; N, 10.45. ESI+-MS, m/z: 580 [M + Na]+. IR
(KBr, selected bands, cm-1): 3252 mw ν(N-H); 2976 m, 2945
mw, 2935 mw ν(C-H); 2214 s ν(Ct N); 1734m, 1679 vs, 1616 m
ν(CdO) + ν(CdN); 1542 vs ν(CcarbenedN); 744 m δ(C-H from
1
Ar). H NMR (CDCl3, δ): 10.67 (s, br, 1H, NH), 7.98-7.26 (m,
[PdCl{C(NdC(C6H2(Cl2)CON))dN(H)C6H3(2,6-Me2)}{Ct NC6-
H3(2,6-Me2)}] (18). Anal. Calcd for C26H21N4Cl3OPd: C, 50.51;
H, 3.42; N, 9.06. Found: C, 50.79; H, 3.42; N, 8.58. ESI+-MS,
m/z: 549 [M - 2Cl]+. IR (KBr, selected bands, cm-1): 3210 m
ν(N-H); 3037 mw, 2971 mw, 2921 w, 2855 mw ν(C-H); 2197 s
ν(Ct N); 1728 vs, 1677 m ν(CdO) + ν(CdN); 1536 vs
ν(CcarbenedN); 770 s δ(C-H from Ar). 1H NMR (CDCl3, δ): 10.31
(s, br, 1H, NH), 7.84 and 7.80 (m, 2H) (aryls from the isoindolinone
moiety), 7.27-7.17 (m, 6H, aryls), 2.60 (s, 3H), 2.51 (s, 3H) and
2.30 (s, 6H, Me). 13C{1H} NMR (CDCl3, δ): 201.1 (CcarbenedN),
186.1 (CdO), 171.2 (CdN), 136.5, 136.4, 133.9, 131.0, 130.1,
128.4, 128.2, 128.1, 128.0, 125.9, 125.6, 125.3 (aryls), 18.7 and
18.5 (Me).
4H, aryls), 2.50 (s) and 2.48 (s, 3H, Me), 1.64 (s, 9H) and 1.54 (s,
9H, But). 13C{1H} NMR (CDCl3, δ): 199.9 (CcarbenedN), 172.0
(CdO), 166.4 (CdN), 145.6, 144.7, 144.5, 134.8, 134.3, 132.8,
124.1, 124.0, 123.4, 123.0 (aryls), 53.0 (CMe3), 29.9 and 27.9
(CMe3), 22.0 and 21.9 (Me).
[PtCl{C(NdC(C6H2(Cl2)CON))dN(H)But}(Ct NBut)] (24).
Anal. Calcd for C18H21N4Cl3OPt: C, 35.39; H, 3.47; N, 9.17. Found:
C, 36.01; H, 3.48; N, 9.23. ESI+-MS, m/z: 634 [M + Na]+. IR
(KBr, selected bands, cm-1): 3234 mw ν(N-H); 2980 mw and
2872 w ν(C-H); 2230 m ν(Ct N); 1728 m, 1673 mw, 1618 w
ν(CdO) + ν(CdN); 1545 vs ν(CcarbenedN); 723 s δ(C-H). 1H
NMR (CDCl3, δ): 10.56 (s, br, 1H, NH), 7.84 (s, 1H) and 7.73 (s,

Palladium and Platinum Iminocarbene Species
Organometallics, Vol. 27, No. 20, 2008 5389
1H) (aryls), 1.63 (s, 9H) and 1.54 (s, 9H, But). 13C{1H} NMR
(CDCl3, δ): 199.8 (CcarbenedN), 174.3 (CdO), 169.7 (CdN), 137.8,
136.6, 133.4, 125.5, 125.2 (aryls), 115.1 (Ct N), 60.2 and 58.1
(CMe3), 23.2 and 22.0 (CMe3).
2 h at 20-25 °C, and during this period the color of the mixture
turned from yellowish-brown to bright lemon-orange. After 2 h,
the reaction mixture was evaporated at 20-25 °C to dryness under
a stream of N2, and the solid residue was extracted with two 5 mL
portions of cold (10 °C) CHCl3. The bright yellow-orange solution
was filtered off to remove some insoluble material, and the filtrate
was evaporated to dryness under a stream of N2 at room temper-
ature, washed with two 5 mL portions of Pri2O and five 10 mL
portion of cold (5 °C) Et2O, and dried in Vacuo at 20-25 °C.
[PtCl(C6H4CONCNH)(Ct NBut)2] (34). ESI+-MS, m/z: 543 [M]+.
IR (KBr, selected bands, cm-1): 3242 m ν(N-H); 2896 w, 2855
mw ν(C-H); 2253 and 2239 s ν(Ct N); 1770 vs, 1673 m ν(CdO)
[PtCl{C(NdC(C6H4CON))dN(H)C6H3(2,6-Me2)}{Ct NC6H3-
(2,6-Me2)}] (25). Anal. Calcd for C26H23N4ClOPt: C, 48.95; H, 3.63;
N, 8.78. Found: C, 48.90; H, 3.78; N, 8.58. ESI+-MS, m/z: 603
[M - Cl]+. IR (KBr, selected bands, cm-1): 3227 mw ν(N-H);
2961 mw, 2951 w, 2941 mw ν(C-H); 2192 s ν(C≡N); 1717 vs,
1677 s, 1619 w ν(CdN) + ν(CdO); 1522 vs ν(CcarbenedN); 723 s
δ(C-H from Ar). 1H NMR (CDCl3, δ): 10.19 (s, br, 1H, NH),
7.82-7.69 (m, 4H) (aryls from isoindolinone moiety), 7.27-7.15
(m, 6H, aryls), 2.59 (s, 6H) and 2.30 (s, 6H, Me). 13C{1H} NMR
(CDCl3, δ): 197.6 (CcarbenedN), 182.0 (CdO), 174.2 (CdN), 136.6,
135.5, 134.2, 133.8, 132.1, 129.1, 128.4, 128.2, 127.9, 124.3, 123.1
(aryls), 19.2 and 18.9 (Me).
1
+ ν(CdN); 782 m δ(C-H from Ar). H NMR (CDCl3, δ): 9.56
(s, br, 1H, NH), 7.83-7.41 (m, 4H, aryls), 1.60 (s) and 1.57 (s,
18H, But).
Attempted Reaction between 28 and 7. A suspension of 7 (0.2
mmol) in CHCl3 (2 mL) was added to a solution of 28 (0.2 mmol)
in CHCl3 (5 mL). The reaction mixture was then refluxed for 2 h,
and the color of the mixture turned from yellowish-brown to bright
lemon-orange. After 2 h, the reaction mixture was evaporated at
20-25 °C to dryness under a stream of N2, and the solid residue
was extracted with two 5 mL portions of CHCl3. The bright yellow-
orange solution was filtered off to remove some insoluble material,
and the filtrate was evaporated to dryness under a stream of N2 at
room temperature, washed with five 5 mL portions of Pri2O, 1 mL
portion of cold (5 °C) Et2O, and again with five 5 mL portions of
Pri2O, and dried in Vacuo at 20-25 °C. The obtained dark yellow-
orange solid residue was monitored by TLC, ESI-MS, and 1H and
13C{1H} NMR. The slow evaporation of an acetone solution of
this solid residue in air at 20-25 °C resulted in precipitation of
crystals of 30 suitable for X-ray study.
[PtCl{C(NdC(C6H3(Me)CON))dN(H)C6H3(2,6-Me2)}{Ct NC6-
H3(2,6-Me2)}] (26). Anal. Calcd for C27H25N4ClOPt: C, 49.73; H,
3.86; N, 8.59. Found: C, 49.67; H, 3.78; N, 8.68. ESI+-MS, m/z:
654 [M + H]+. IR (KBr, selected bands, cm-1): 3241 mw ν(N-H);
3030 mw, 2961 w, 2920 mw ν(C-H); 2195 s ν(Ct N); 1712 s,
1674 s ν(CdO) + ν(CdN); 1532 vs ν(CcarbenedN); 723 s δ(C-H
from Ar). 1H NMR (CDCl3, δ): 10.21 (s, br, 1H, NH), 7.75-7.70
(m, 4H) (aryls from the isoindolinone moiety), 7.27-7.14 (m, 6H,
aryls), 2.51 (s, 6H) and 2.22 (s, 6H, Me), 2.44 (s, 3H, Me from the
isoindolinone moiety). 13C{1H} NMR (CDCl3, δ): 196.9
(CcarbenedN), 186.2 (CdO), 167.9 (CdN), 136.7, 136.6, 136.2,
134.0, 131.0, 130.4, 128.5, 128.2, 128.1 (aryls), 21.2 (Me from
the isoindolinone moiety), 21.7 and 18.4 (Me).
[PtCl{C(NdC(C6H2(Cl2)CON))dN(H)C6H3(2,6-Me2)}{Ct NC6-
H3(2,6-Me2)}] (27). Anal. Calcd for C26H21N4Cl3OPt: C, 44.18; H,
2.99; N, 7.93. Found: C, 44.19; H, 2.80; N, 8.12. ESI+-MS, m/z:
672 [M - Cl]+. IR (KBr, selected bands, cm-1): 3242 m ν(N-H);
3035 mw, 2964 mw, 2921 w, 2855 mw ν(C-H); 2195 s ν(Ct N);
1736 vs, 1686 m ν(CdO) + ν(CdN); 1520 vs ν(CcarbenedN); 779 s
δ(C-H from Ar). 1H NMR (CDCl3, δ): 10.21 (s, br, 1H, NH),
7.84 (s, 1H) and 7.82 (s, 1H) (aryls from the isoindolinone moiety),
7.34-7.28 and 7.26-7.17 (m, 6H, aryls), 2.62 (s, 6H) and 2.30 (s,
6H, Me). 13C{1H} NMR (CDCl3, δ): 202.1 (CcarbenedN), 186.2
(CdO), 171.0 (CdN), 136.1, 132.7, 130.6, 130.4, 128.4, 128.3,
128.1, 128.0, 125.9, 125.6, 125.3 (aryls), 20.7 and 18.6 (Me).
Crystals of 27 suitable for single-crystal X-ray diffraction study
were obtained upon slow evaporation of 10:1 (v/v) acetone-toluene
solutions of 27 in air at ca. 20-25 °C.
Acknowledgment. This work has been partially supported
by the Fundac¸a˜o para a Cieˆncia e a Tecnologia (FCT),
Portugal, and its POCI 2010 program (FEDER funded).
K.V.L. expresses gratitude to FCT and the POCI program
(FEDER funded), Portugal, for a fellowship (grant SFRH/
BPD/27094/2006). It has also been supported by the RAS
Presidium Program (grant 8P) and the Academy of Finland
(grant 110465).
Supporting Information Available: Crystallographic data in
CIF format for complexes 10, 27, and 30. This material is available
free of charge via the Internet at http://pubs.acs.org.
Attempted Reaction between 5 and 7. A suspension of 7 (0.2
mmol) in CHCl3 (2 mL) was added to a solution of 6 (0.2 mmol)
in CHCl3 (5 mL). The reaction mixture was then left to stand for
OM800517C