Dimethylplatinum(II) complexes [PtMe2(NN)], with NN = diimine ligand, can react with dichloromethane or chloroform solvent to give the corresponding organoplatinum(IV) complexes [PtClMe2(CH2Cl)(NN)] or [PtClMe2(CHCl2)(NN)], respectively. The products can exist in isomeric forms, corresponding to products of cis or trans oxidative addition. The structures of three dichloromethane adducts and one chloroform adduct are reported.

The new, unsymmetrical azobenzene-tagged ligand 4-(4-azobenzene)-3,6-di(2-pyridyl)pyridazine, adpp, forms complexes with platinum(II) and platinum(IV), which exist as a mixture of geometrical isomers. The complexes are characterized primarily by their NMR spectra, while the structures of the ligand and its complexes [PtMe2(adpp)], [PtBrMe2(CH2C6H4-4-t-Bu)(adpp)], and [PtBrMe2(CH2C6H3-3,5-t-Bu2)(adpp)] have been structurally characterized. In solution, the compounds undergo easy photochemical trans−cis switching of the azobenzene group, with subsequent slow thermal isomerization back to the more stable trans-azobenzene isomer.

The reaction of the cyclic peroxides cyclobutane malonoyl peroxide and cyclopentane malonoyl peroxide to dimethylplatinum(II) complexes with the bidentate nitrogen donor ligand 4,4=-di-t-butyl-2,2=-bipyridine (bubpy) gave a mixture of the products of cis and trans oxidative addition, [PtMe 2 {(O 2 C) 2 C(C 3 H 6 )}(bubpy)] and [PtMe 2 {(O 2 C) 2 C(C 4 H 8 )}(bubpy)], respectively. The cis isomers exist with a chelating dicarboxylate ligand, forming a six-membered ring, while the trans isomers are thought to exist as oligomers, which may react with water or solvent to give complexes containing a monodentate dicarboxylate ligand. Equilibration of the product of cis oxidative addition, cis-[PtMe 2 {(O 2 C) 2 C(C 3 H 6 )}(bubpy)], with oxalic or phthalic acid to give equilibria with the oxalate cis-[PtMe 2 (O 4 C 2 )(bubpy)] or phthalate cis-[PtMe 2 {(O 2 C) 2 C 6 H 4 }(bubpy)] derivative, respectively, indicated the expected sequence of chelate stability oxalate > cyclobutane malonate > phthalate. Résumé: La réaction de peroxydes cycliques, le peroxyde de cyclobutane malonoyle et le peroxyde de cyclopentane malonoyle, avec des complexes de diméthylplatine (II) en présence du 4,4=-di-t-butyl-2,2=-bipyridine (bubpy), ligand bidentate donneur d'azote, a formé un mélange de produits d'addition oxydante cis et trans, le [PtMe 2 {(O 2 C) 2 C(C 3 H 6 )}(bubpy)] et le [PtMe 2 {(O 2 C) 2 C(C 4 H 8 )}(bubpy)], respectivement. Les complexes avec un ligand dicarboxylate chélatant existent sous forme d'isomères cis et forment un cycle à six atomes, tandis qu'on croit que les isomères trans existent sous forme d'oligomères qui peuvent réagir avec l'eau ou un solvant pour produire des complexes comprenant un ligand dicarboxylate monodentate. L'équilibration du produit d'addition oxydante cis, le cis-[PtMe 2 {(O 2 C) 2 C(C 3 H 6 )}(bubpy)], avec l'acide oxalique ou phtalique qui se produit pour former respectivement à l'état d'équilibre les dérivés cis-[PtMe 2 (O 4 C 2 )(bubpy)] oxalate ou cis-[PtMe 2 {(O 2 C) 2 C 6 H 4 }(bubpy)] phtalate, révèle la séquence de stabilité attendue des chélates : oxalate > malonate de cyclobutane > phthalate. [Traduit par la Rédaction]