Reactivity of a Dimethylplatinum(II) Complex with the Bis(2-pyridyl)dimethylsilane Ligand: Easy Silicon–Carbon Bond Activation

Abstract

The compound [PtMe2(bps)] (1; bps = bis(2-pyridyl)dimethylsilane) undergoes easy oxidative addition with bromine, iodine, methyl iodide, or methyl triflate to give [PtBr2Me2(bps)], [PtI2Me2(bps)], [PtIMe3(bps)], or [PtMe3(OH2)(bps)][OTf], respectively. The complex [PtIMe3(bps)] is slowly hydrolyzed in solution, with cleavage of the pyridyl–silicon bonds, to give [PtIMe3(py)2] and (Me2SiO) n . In contrast, oxidation of 1 with oxygen/CF3CH2OH, hydrogen peroxide, or dibenzoyl peroxide/H2O occurs with cleavage of a methyl–silicon bond to give [PtMe(bps)-μ-{κ3 N,N,O-OSiMe(2-C5H4N)2PtMe3][CF3CH2OB(C6F5)3], [PtMe3{κ3 N,N,O-(2-C5H4N)2SiMeO}], or [PtMe3{κ3 N,N,O-(2-C5H4N)2SiMeOH}][PhCOO], respectively. Mechanistic studies indicate that this methyl transfer from silicon to platinum occurs after oxidation to platinum(IV) and is induced by hydroxide attack at silicon.

Reactivity comparison of five-and six-membered cyclometalated platinum(ii) complexes in oxidative addition reactions

“…For Pt(1), the disorder C(1)/I(2) is about 5% I and for Pt (2), the disorder C(33)/I(4) is about 8%. There are two molecules of 3 in the asymmetric unit.…”

“…This compound had been previously synthesized by the reaction of [PtCl 2 (DMSO) 2 ] with SnMe 4 at 80 °C for 24 h with yield of 55%. 26 …”

“…2 Although the most well-studied examples of these compounds are five-membered ring complexes containing N−Pt−C(phenyl) moiety, [3][4][5] six-membered cyclometalated complexes are relatively rare. 2 Although the most well-studied examples of these compounds are five-membered ring complexes containing N−Pt−C(phenyl) moiety, [3][4][5] six-membered cyclometalated complexes are relatively rare.…”

Oxidation of dimethylplatinum(II) complexes with malonyl peroxide derivatives

“…The oxidative addition of hydrogen peroxide might occur by a polar mechanism (A to B to C, Scheme 1) or a concerted mechanism (A to D to E, Scheme 1) and these are expected to lead initially to cis or trans addition, but easy Pt−O bond cleavage might then give an easy route to isomerization (via five-coordinate intermediates B and F, which may be reversibly solvated, Scheme 1). 17,19,21,22,[32][33][34] Similar mechanisms are possible for oxidative addition reactions of diacyl peroxides. 23,34 In an attempt to distinguish between the polar and concerted mechanisms for peroxide oxidative addition, the reactions of phthaloyl peroxide with several dimethylplatinum(II) complexes with diimine ligands were studied (Scheme 2).…”

“…17,19,21,22,[32][33][34] Similar mechanisms are possible for oxidative addition reactions of diacyl peroxides. 23,34 In an attempt to distinguish between the polar and concerted mechanisms for peroxide oxidative addition, the reactions of phthaloyl peroxide with several dimethylplatinum(II) complexes with diimine ligands were studied (Scheme 2). 30 It was argued that a polar mechanism should lead to an intermediate G and then to a kinetic trans adduct I rather than the cis chelate complex H, which was expected to be thermodynamically more stable.…”