Oxidative Addition of Phthaloyl Peroxide to Dimethylplatinum(II) Complexes

Abstract

Complexes [PtMe 2 (NN)], with NN = 2,2′-bipyridine (bipy), 4,4′-ditert-butyl-2,2′-bipyridine (bu 2 bipy), di-2-pyridylamine (dpa), or di-2-pyridyl ketone (dpk), react easily with phthaloyl peroxide to give a mixture of the chelate complex [PtMe 2 {κ 2 -O,O′-1,2-(O 2 C) 2 C 6 H 4 }(NN)], which was structurally characterized when NN = bu 2 bipy, and an oligomer or polymer [PtMe 2 {μ-κ 2 -O,O′-1,2-(O 2 C) 2 C 6 H 4 }-(NN)] n . In the case with NN = dpa, no phthalate chelate complex is formed. These complexes are easily hydrolyzed, and the complexes cis-[PtMe 2 (OH){κ 1 -O-O 2 CC 6 H 4 -2-CO 2 H}(bipy)] and trans-[PtMe 2 {κ 1 -O-O 2 CC 6 H 4 -2-CO 2 H}(dpkOH)]have been structurally characterized. It is argued that the oxidative addition of phthaloyl peroxide occurs by a polar mechanism and that the hydrolysis is easy because there is no special stability associated with the seven-membered platinumphthalate chelate ring.

Oxidation of dimethylplatinum(II) complexes with malonyl peroxide derivatives

“…This is analogous to calculated intermediates with other peroxides, although none has been detected directly. 25,26,30 However, the analogous intermediate [PtMe 2 (I 2 )(bipy)], formed by addition of iodine, has been detected by using low-temperature NMR spectroscopy. 59,60 The calculated bond distance O··O = 2.17 Å in [PtMe 2 (CBMP)(bipy)] is considerably longer than in the free peroxide CBMP (calculated 1.58 Å, experimental 1.48 Å) 46 but the bond is sufficiently strong to keep the carboxylate groups roughly coplanar (Fig.…”

“…There are obvious similarities to the proposed mechanism of oxidative addition of PP, shown in Scheme 2. 30 However, there are significant differences that make the mechanistic interpretation more convincing for the malonoyl peroxide reactions. These arise from the greater stability of the six-membered platinum-malonate compared to the seven-membered platinum-phthalate chelate ring.…”

“…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. The reaction typically gave a mixture of these products, and both were susceptible to hydrolysis to give J or K (Scheme 2).…”

“…The cis chelate complex H had no special stability, and so the strategy was only partly successful. 30 The complication is thought to arise because H contains a seven-membered chelate ring for which the chelate effect is less marked than for five-or six-membered rings. 35,36 In the present work, the reagents cyclobutane malonoyl peroxide, CBMP, and cyclopentane malonoyl peroxide, CPMP, have been used to react with the electron-rich dimethylplatinum(II) complex 1 (Chart 1).…”

C−O coupling of Malonyl Peroxides with Enol Ethers via [5+2] Cycloaddition: Non‐Rubottom Oxidation

“…[1] Recently we reported efficient methods for oxidative CÀ O coupling of β-dicarbonyl [2] and Nheterocyclic [3] compounds with diacyl peroxides, in which one of the reagents, diacyl peroxide, acts both as an O-component and as an oxidizing agent. Cyclic diacyl peroxides firstly prepared in the 1950 s [4] were rediscovered a few years ago, [5] when previously practically unavailable reactions stereoselective syn- [6] and anti-dihydroxylation [7] of alkenes, arene oxidation, [8] alkene oxyamination, [9] and dioxygenation, [10] Hofmann-Löffler-Freytag-type reaction, [11] selective sulfide oxidation, [12] peracids formation, [13] ring opening/halogenation of cycloalkanols, [14] and the [3 + 2] cycloaddition of arynes to azides [15] were realized. High oxidative ability, cyclic structure and absence of an acidic proton attached to the peroxide group favorably differ malonyl peroxides from related oxidants -peracids and noncyclic diacyl peroxides.…”