ion. The oxidative addition mechanism was originally proposed22i because of the lack of a strong rate dependence on polar factors and on the acidity of the medium. Later, however, the electrophilic substitution mechanism also was proposed. Recently, the oxidative addition mechanism was confirmed by investigations into the decomposition and protonolysis of alkylplatinum complexes, which are the reverse of alkane activation. There are two routes which operate in the decomposition of the dimethylplatinum(IV) complex Cs2Pt(CH3)2Cl4. The first route leads to chloride-induced reductive elimination and produces methyl chloride and methane. The second route leads to the formation of ethane. There is strong kinetic evidence that the ethane is produced by the decomposition of an ethylhydridoplatinum(IV) complex formed from the initial dimethylplatinum(IV) complex. In D2O-DCl, the ethane which is formed contains several D atoms and has practically the same multiple exchange parameter and distribution as does an ethane which has undergone platinum(II)-catalyzed H-D exchange with D2O. Moreover, ethyl chloride is formed competitively with H-D exchange in the presence of platinum(IV). From the principle of microscopic reversibility it follows that the same ethylhydridoplatinum(IV) complex is the intermediate in the reaction of ethane with platinum(II). Important results were obtained by Labinger and Bercaw62c in the investigation of the protonolysis mechanism of several alkylplatinum(II) complexes at low temperatures. These reactions are important because they could model the microscopic reverse of C-H activation by platinum(II) complexes. Alkylhydridoplatinum(IV) complexes were observed as intermediates in certain cases, such as when the complex (tmeda)Pt(CH2Ph)Cl or (tmeda)PtMe2 (tmeda ) N,N,N′,N′-tetramethylenediamine) was treated with HCl in CD2Cl2 or CD3OD, respectively. In some cases H-D exchange took place between the methyl groups on platinum and the, CD3OD prior to methane loss. On the basis of the kinetic results, a common mechanism was proposed to operate in all the reactions: (1) protonation of Pt(II) to generate an alkylhydridoplatinum(IV) intermediate, (2) dissociation of solvent or chloride to generate a cationic, fivecoordinate platinum(IV) species, (3) reductive C-H bond formation, producing a platinum(II) alkane σ-complex, and (4) loss of the alkane either through an associative or dissociative substitution pathway. These results implicate the presence of both alkane σ-complexes and alkylhydridoplatinum(IV) complexes as intermediates in the Pt(II)-induced C-H activation reactions. Thus, the first step in the alkane activation reaction is formation of a σ-complex with the alkane, which then undergoes oxidative addition to produce an alkylhydrido complex. Reversible interconversion of these intermediates, together with reversible deprotonation of the alkylhydridoplatinum(IV) complexes, leads to multiple H-D exchange

Activation of c-h bonds by metal complexes

The main advances in the title area are reviewed with emphasis on catalytic alkane functionalization, both organometallic and bioinorganic. Current challenges are discussed. A tunable, selective hydrocarbon functionalization is still out of reach and resolving mechanistic problems has proved particularly challenging.

Alkane C–H activation and functionalization with homogeneous transition metal catalysts: a century of progress—a new millennium in prospect

New Directions in Inorganic and Metal-Organic Coordination Chemistry in Supercritical Fluids

Metal–dihydrogen and σ-bond coordination: the consummate extension of the Dewar–Chatt–Duncanson model for metal–olefin π bonding

Transition Metal Alkane Complexes

Octahedral metal carbonyls. XXI. Carbonyl and metal-carbon stretching spectra of monosubstituted group VIB metal carbonyls☆☆☆

Infrared Spectra and Structures of Metal Carbonyl Derivatives. III. Acetylene and Olefin Derivatives of Group VI Metal Carbonyls

"Mixed" Complexes of Group VIb Metal Carbonyls

Evidence for the Existence of Group VI Metal Pentacarbonyls

The Infrared Spectrum and Evidence for the Structure of a New Metal Carbonyl

Gerard R. Dobson

Papers

Octahedral metal carbonyls. XXI. Carbonyl and metal-carbon stretching spectra of monosubstituted group VIB metal carbonyls☆☆☆

Infrared Spectra and Structures of Metal Carbonyl Derivatives. III. Acetylene and Olefin Derivatives of Group VI Metal Carbonyls

"Mixed" Complexes of Group VIb Metal Carbonyls

Evidence for the Existence of Group VI Metal Pentacarbonyls

The Infrared Spectrum and Evidence for the Structure of a New Metal Carbonyl