Reactions of methyl- and phenylplatinum(II) complexes with isocyanides. Mechanism of the insertion reaction

Treichel, P. M.; Wagner, Kirsten; Hess, R. W.

doi:10.1021/ic50125a002

Cited by 37 publications

(10 citation statements)

References 2 publications

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“…During the migration step, the complex converts from an ionic species into a neutral species giving rise to disorder in the orientation of the solvent molecules and a positive value for Δ S . This indicates that the transition state of the migration reaction resembles the neutral final state and might, therefore, look like a five-coordinate neutral species having the halide atom coordinated to the metal center, as proposed previously for isocyanide insertion into (PR 3 ) 2 Pt(R)X complexes …”

Section: Discussionsupporting

confidence: 73%

“…From the results, it is clear that the mechanism of isocyanide insertion involves coordination of the isocyanide to the metal via displacement of the chloride atom, followed by a rate-determining migration of the methyl group to the precoordinated isocyanide. Such a mechanism has been proposed before for isocyanide insertion into palladium− and platinum−carbon bonds. ,,, The complex trans -[PdCl(2-pyrazyl)(PPh 3 ) 2 ] 59 undergoes migratory insertion of TIC via Pd−X bond breaking, although there are indications for a mechanism involving Pd−P bond breaking.…”

Section: Discussionmentioning

confidence: 82%

“…Such a mechanism has been proposed before for isocyanide insertion into palladium-and platinum-carbon bonds. 39,41,58,59 The complex trans-[PdCl(2-pyrazyl)(PPh 3 ) 2 ] 59 undergoes migratory insertion of TIC via Pd-X bond breaking, although there are indications for a mechanism involving Pd-P bond breaking.…”

Section: Resultsmentioning

confidence: 99%

“…The migration rate is enhanced by R groups on the isocyanide having electronwithdrawing properties, such as a tosylmethyl group, and it is reduced by an electron-donating R group, such as tert-butyl. In earlier studies, it has already been shown that p-chlorophenyl isocyanide inserts with a higher rate than methyl isocyanide into the Pd-R′ bond of (PR 3 ) 2 Pt(R′)X (R′ ) CH 3 , C 6 H 5 ; X ) Br, I), 58 and analogously, the insertion of isocyanides with electronwithdrawing R groups into the Pd-acetylide bond of the complexes X(R 3 P) 2 PdCCPd(PR 3 )X is faster than the insertion of isocyanides having electron-donating R groups. 41 As can be seen from Table 3, the migration step involves relatively high activation enthalpies and positive activation entropies.…”

Section: Discussionmentioning

confidence: 97%

“…This indicates that the transition state of the migration reaction resembles the neutral final state and might, therefore, look like a five-coordinate neutral species having the halide atom coordinated to the metal center, as proposed previously for isocyanide insertion into (PR 3 ) 2 Pt(R)X complexes. 58 The interesting observation that product formation occurs from intermediates 4a-c and 5a-c even in the solid state shows that in the crystal lattice movement of the methyl group to the precoordinated isocyanide and subsequent movement of the chloride atom from the second coordination sphere to the palladium atom occurs, albeit at a lower rate.…”

Section: Discussionmentioning

confidence: 99%

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Isocyanide Insertion into the Palladium−Carbon Bond of Complexes Containing Bidentate Nitrogen Ligands: A Structural and Mechanistic Study

Delis¹,

Aubel²,

Vrieze³

et al. 1997

Organometallics

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Isocyanide insertion into the palladium-carbon bond of complexes containing bidentate nitrogen ligands; A structural and mechanistic study Delis, J.G.P.; Aubel, P.G.; Vrieze, K.; van Leeuwen, P.W.N.M.; Veldman, N.; Spek, A.L.; van Neer, F.J.R. Published in: Organometallics DOI:10.1021/om970096eLink to publication Citation for published version (APA):Delis, J. G. P., Aubel, P. G., Vrieze, K., van Leeuwen, P. W. N. M., Veldman, N., Spek, A. L., & van Neer, F. J. R. (1997). Isocyanide insertion into the palladium-carbon bond of complexes containing bidentate nitrogen ligands; A structural and mechanistic study. Organometallics, 16, 2948-2957. DOI: 10.1021/om970096e General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Insertion of the isocyanides 2,6-dimethylphenyl isocyanide (DIC), tert-butyl isocyanide (TIC) and tosylmethyl isocyanide (TosMIC) into the Pd-Me bond of complexes (NkN)Pd(Me)Cl (NkN ) 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 2,2′-bipyrimidine (bpm)) afforded quantitatively (NkN)Pd(C(dNsR)Me)Cl (R ) 2,6-Me 2 C 6 H 3 , t-Bu, CH 2 Tosyl). The course of the reaction has been shown to proceed via the intermediates [(NkN)Pd(CN-R)(Me)]Cl (NkN ) bpy, phen; R ) 2,6-Me 2 C 6 H 3 , t-Bu, CH 2 Tosyl), which have been characterized at 250 K by NMR and IR spectroscopies and conductivity measurements. The mechanism of the insertion reaction involves substitution of the halide by the isocyanide followed by a rate-determining methyl migration to the precoordinated isocyanide. Kinetic measurements of the isocyanide insertion reaction, which provided the reaction rate constants of the isocyanide association (k 1 ), isocyanide dissociation (k -1 ), and methyl migration reaction (k 2 ), have demonstrated that the migration rate of the methyl group to the precoordinated isocyanide increases with increasing electrophilicity of the isocyanide. Methyl migration in the intermediate complexes [(NkN)Pd(CN-R)(Me)]Cl (NkN ) bpy, phen; R ) 2,6-Me 2 C 6 H 3 , t-Bu, CH 2 Tosyl) also occurs in the solid state. The complexes (NkN)Pd(C(dNsR)Me)X (NkN ) bpy, phen; R ) t-Bu, CH 2 Tosyl; X ) Cl, Br) show a fluxional behavior due to a site exchange of the nitrogen donor atoms. Spin saturation transfer 1 H NMR experiments showed that the mechanism of this process involves Pd-N bond breaki...

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Section: Discussionsupporting

confidence: 73%