Insertion of molecular oxygen into a palladium(II) methyl bond: A radical chain mechanism involving palladium(III) intermediates

Journal of the American Chemical Society

Volumn 131, Issue 43, 2009, Pages 15802-15814

  Boisvert, Luc ^a   Denney, Melanie C ^a   Hanson, Susan Kloek ^a   Goldberg, Karen I ^a  

^a UNIVERSITY OF WASHINGTON   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALKYL COMPLEXES; BIPYRIDINES; CHAIN PROPAGATION; EARLY TRANSITION METALS; FIRST-ORDER; HOMOLYTIC SUBSTITUTION; KINETIC STUDY; MAIN GROUP; OXYGEN INSERTION; RADICAL CHAIN MECHANISMS; RADICAL INITIATORS; RATE LAWS;

ALKYLATION; MECHANISMS; MOLECULAR OXYGEN; OXIDATION; PALLADIUM; REACTION RATES; SULFUR COMPOUNDS; TRANSITION METALS;

PALLADIUM COMPOUNDS;

2,2' AZOBIS(2 METHYLPROPIONITRILE); NITRILE; OXYGEN; PALLADIUM; UNCLASSIFIED DRUG;

ARTICLE; CARBON NUCLEAR MAGNETIC RESONANCE; CHEMICAL REACTION; CHEMICAL STRUCTURE; OXIDATION; SYNTHESIS;

EID: 70350678840     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9061932     Document Type: Article

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165. (b) Wadhwani, P.; Bandyopadhyay, D. Organometallics 2000, 19, 4435.
166. The following reaction between a first-row transition metal complex (often with L ) macrocyclic nitrogen ligand; M ) Cr, Mn, Fe, Co, Ni, and also Cu) and Me• or MeOO• radicals in aqueous medium is well documented: (L)Mn(H2O) + R• T (L)Mn+1(R) + H2O. For reactions involving MeOO• , values of Keq ) 102-103 have been determined for Fe (ref d) and Cu (ref e) complexes, while the reaction seems to be essentially irreversible for some Co complexes (refs f and g). (a) Goldstein, S.; Czapski, G.; van Eldik, R.; Shaham, N.; Cohen, H.; Meyerstein, D. Inorg. Chem. 2001, 40, 4966.
167. (b) van Eldik, R.; Meyerstein, D. Acc. Chem. Res. 2000, 33, 207.
168. (c) van Eldik, R.; Cohen, H.; Meyerstein, D. Inorg. Chem. 1994, 33, 1566.
169. (d) Mansano- Weiss, C.; Cohen, H.; Meyerstein, D. J. Inorg. Biochem. 2002, 91, 199.
170. (e) Mansano-Weiss, C.; Masarwa, A.; Cohen, H.; Meyerstein, D. Inorg. Chim. Acta 2005, 358, 2199.
171. (f) Solomon-Rapaport, E.; Masarwa, A.; Cohen, H.; Valentine, J. S.; Meyerstein, D. Eur. J. Inorg. Chem. 2002, 2427.
172. (g) Solomon-Rapaport, E.; Masarwa, A.; Cohen, H.; Meyerstein, D. Inorg. Chim. Acta 2000, 299, 41.
173. The coupling of R• with O2 to form ROO• is essentially diffusionlimited (for compilations of rate data see refs a and b). A value of k ) 4.7 × 109 M-1 s-1 has been determined for the reaction of Me• with O2 in H2O at 296 K (ref c). (a) Neta, P.; Huie, R. E.; Ross, A. B. J. Phys. Chem. Ref. Data 1990, 19, 413.
174. (b) Neta, P.; Grodkowski, J.; Ross, A. B. J. Phys. Chem. Ref. Data 1996, 25, 709.
175. (c) Thomas, J. K. J. Phys. Chem. 1967, 71, 1919.
176. The homocoupling of two alkyl radicals (Me • in cyclohexane at 298 K: k ) 1.6 × 109 M-1 s-1, ref a) is essentially diffusion-limited. The rate constant for the homocoupling of two MeOO• radicals in benzene at 295 K is k ) 1.9 × 108 M-1 s-1 (ref b). (a) Carlsson, D. J.; Ingold, K. U. J. Am. Chem. Soc. 1968, 90, 7047.
177. (b) Khursan, S. L.; Safiullin, R. L.; Martemianov, V. S.; Nikolayev, A. V.; Urozhai, I. A. React. Kinet. Catal. Lett. 1989, 39, 261. For a compilation of rate data, see ref 61b.
178. No chemically induced dynamic nuclear polarization (CIDNP) effects were observed during the reactions between 1 and O2. Weak CIDNP effects have been observed in some non-chain homolytic displacements at Pt(II) centers (see ref 54b, see also ref 42h) while no effects were detected for some radical chain reactions (see ref 55, also ref 57a). For the observation of strong CIDNP effects in the autoxidation of boranes, see ref 15q.
179. Apart from the processes described in note 60, rate constants for the addition of radicals to transition metal complexes have rarely been measured. (a) The rate constant for the addition of iPr • radicals to (phen)PtMe2 (ref 57b) and to trans-IrClCO(PMe3)2 was estimated to be k ≈ 107 M-1 s-1: Labinger, J. A.; Osborn, J. A.; Coville, N. J. Inorg. Chem. 1980, 19, 3236.
180. (b) In ref 41g, the rate constant for the addition of the 5-hexenyl radical to Pt(PEt3)3 was estimated to be k ≈ 106 M-1 s-1.
181. (c) In ref 45a, for the equilibrium [(L)NiII]2+ + Me• + H2O T [(L)(H2O)NiIII(Me)]2+, values of the rate constant for the forward reaction with three different complexes were determined to be kforward ) 1.6-6.5 × 108 M-1 s-1, and the equilibrium constant for five different complexes were found to be Keq ) 450-12000 M-1.
182. (d) Both the forward and reverse reactions involving the Lewis acidbase adduct [(acetylacetonato)2PtII • • • I2] for the equilibrium reaction I• + [(acetylacetonato)2PtII • • • I2] T (acetylacetonato)2PtIV(I)2 + I • were found to be diffusion-controlled, with an equilibrium constant of Keq ) 0.694: Hopgood, D.; Jenkins, R. A. J. Am. Chem. Soc. 1973, 95, 4461.
183. See note 45 for similar reactivity in nonchain radical reactions with transition metal complexes. The two-step transformation LCoII + MeOO• f LCoIII(OOMe) followed by LCoIII(OOMe) + MeOO• f products has been studied, see refs 60f, g.
184. Hammond, G. S.; Boozer, C. E.; Hamilton, C. E.; Sen, J. N. J. Am. Chem. Soc. 1955, 77, 3238.
185. (a) Denney, M. C.; Smythe, N. A.; Cetto, K. L.; Kemp, R. A.; Goldberg, K. I. J. Am. Chem. Soc. 2006, 128, 2508.
186. (b) Keith, J. M.; Muller, R. P.; Kemp, R. A.; Goldberg, K. I.; Goddard, W. A., III; Oxgaard, J. Inorg. Chem. 2006, 45, 9631.
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194. For example, singlet oxygen generated by photosensitization was implicated in a recently reported example of oxygen insertion into a Pt(II)-Me bond to form a Pt(II)-OOMe complex. See ref 12.