Mechanistic studies of the hydrogen isotope exchange reaction catalysed by homogeneous platinum salts

30 Years with ortho‐directed hydrogen isotope exchange labelling

“…Although this system has a much narrower field of applicability, only functioning well with carboxylate 23 Overall, the kinetic studies showed similarities with the non-specific K 2 PtCl 4 homogeneous system studied by earlier workers 24 and, taken together with the 3 H-NMR regiochemical studies we carried out, enabled us to further support the postulated 5-membered cyclometallated intermediate initially suggested as a key step in the reaction at Kansas City in 1982.…”

Organometallic alkane CH activation

“…Garnett and coworkers [12][13][14][15] found that H/D exchange in polycyclic aromatic hydrocarbons and heterocycles is homogeneously catalyzed by platinum(II) salts in deuterated aqueous acid medium. Exchange even occurred several carbons out along the alkyl chain of alkylaromatics, a point that led Shilov and coworkers [1,16] to extend the system to alkanes where they saw slow but definite exchange at modest temperatures.…”

Mechanistic Aspects of C−H Activation by Pt Complexes

“…Reactions with cyclohexane were reported to be slow, but no further details were given. Mechanistic details of the aromatic C−H activation were later reported in a series of remarkable papers. ,− Despite early attempts by Garnett and Hodges to induce aliphatic C−H activation, it was Shilov and co-workers who in 1969 were the first to successfully achieve H/D exchange into methane and ethane . Influenced by the success of Garnett and Hodges (see section 1) with K 2 PtCl 4 , Shilov chose the same system for reactions with methane and ethane.…”

“…Catalyst stability and Pt black formation, possibly by Pt(II) disproportionation, were early issues with the aqueous Pt(II) systems . Acidic conditions inhibited disproportionation, although too acidic conditions also inhibited the homogeneous metal-catalyzed H/D exchange and promoted acid-catalyzed exchange. ,, The possible participation of heterogeneous species was also addressed. , The acetic acid also served an important role by solubilizing benzene, precluding a two-phase system. Shteinman et al speculated that a weak chelate complex, possibly Cl 2 Pt(η 2 -HOOCCH 3 ), was the origin of acetic acid stabilization .…”

“…27,66,114 The possible participation of heterogeneous species was also addressed. 27,112 The acetic acid also served an important role by solubilizing benzene, precluding a two-phase system. Shteinman et al speculated that a weak chelate complex, possibly Cl 2 Pt(η 2 -HOOCCH 3 ), was the origin of acetic acid stabilization.…”