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The cycloneophylpalladium(II) complexes [Pd(CH2CMe2C6H4)(κ2-N,N′-L)], 1 or 2, with L = RO(CH2)3N(CH2-2-C5H4N)2, with R = H or Me, respectively, react with either dioxygen or hydrogen peroxide in the presence of NH4[PF6] to give rare examples of the corresponding hydroxopalladium(IV) complexes [Pd(OH)(CH2CMe2C6H4)(κ3-N,N′,N′′-L)][PF6], 3 or 4. The complexes 3 and 4 are stable at room temperature and have been structurally characterized. On heating a solution of 3 or 4 in moist dimethylsulphoxide, selective reductive elimination with C(sp2)–O bond formation is observed, followed by hydrolysis, to give the corresponding pincer complex [Pd(OH)(κ3-N,N′,N′′-L)][PF6] and 2-t-butylphenol as major products. A more complex reaction occurs in chloroform solution. The mechanisms of reaction are discussed, supported by DFT calculations. [ABSTRACT FROM AUTHOR]

The platinum(II) complexes [PtCl(S[Me.sub.2])([[kappa].sup.2]-N,N'-L)]Cl and [PtMe(S[Me.sub.2])([[kappa].sup.2]-N,N'-L)]Cl, L = 2-[C.sub.5][H.sub.4]NC[H.sub.2]NH-x-[C.sub.6][H.sub.4]OH (x = 2, 3, or 4), have been prepared and structurally characterized. In all cases, the complexes form supramolecular polymers in the solid state by NH**Cl and OH**Cl hydrogen bonding to the chloride anion. The ligands are chiral at the amine nitrogen atom, and in all cases, the polymers are isotactic, formed by self-recognition or narcissistic self-assembly. The structures in the crystalline state all have the [Me.sub.2]S ligand trans to pyridyl, but in solution, the methylplatinum(II) complexes isomerise slowly to give an equilibrium with the isomers having the methyl group trans to the pyridyl donor. Key words: platinum, hydrogen bond, supramolecular polymer, isotactic structure. Nous avons prepare les complexes de platine(II) [PtCl(S[Me.sub.2])([[kappa].sup.2]-N,N'-L)]Cl et [PtMe(S[Me.sub.2])([[kappa].sup.2]-N,N'-L)]Cl, L = 2-[C.sub.5][H.sub.4]NC[H.sub.2]NH-x-[C.sub.6][H.sub.4]OH (x = 2, 3 ou 4) et avons caracterise leur structure. Dans tous les cas, les complexes forment des polymeres supramoleculaires a l'etat solide par liaisons hydrogene a l'anion chlorure de types NH**Cl et OH**Cl. Les ligands sont chiraux a l'atome d'azote de l'amine et, dans tous les cas, les polymeres sont isotactiques et se forment par autoreconnaissance ou par autoassemblage narcissique. A l'etat cristallin, les structures presentent toutes le ligand [Me.sub.2]S trans par rapport au groupe pyridyle, tandis qu'en solution, les complexes de methylplatine(II) s'isomerisent lentement vers un equilibre ou les isomeres presentent le groupe methyle trans par rapport au groupe donneur pyridyle. [Traduit par la Redaction] Mots-cles : platine, liaison hydrogene, polymere supramoleculaire, structure isotactique., Introduction The importance of hydrogen bonding for self-assembly of complex structures in nature and in many areas of chemistry is well established, (1-8) as is the significance of platinum complexes [...]

The ligands RN(CH2-2-C5H4N)2 (L1, R = CH2CH2OH; L2, R = CH2CH2CH2OH; L3, R = 2-C6H4OH) have been designed to give dimethylplatinum(II) complexes that can activate dioxygen in the absence of a protic solvent. The ligands react with [Pt2Me4(SMe2)2] to give an equilibrium mixture, with the major constituent being [PtMe2(κ2-N,N'-L)] (1a, L = L1; 1b, L = L2; 1c, L = L3). In the absence of air, 1a reacts with solvent CH2Cl2 to give [PtMe2(CH2Cl)(κ3-N,N',N"-L1]Cl, while 1c decomposes with loss of methane to give [PtMe(κ3-N,N',N"-L3-H)] and then, by reaction with solvent, the binuclear complex [{PtMe(κ3-N,N',N"-L3-H)}2(μ-H)]Cl. In the presence of oxygen the complexes 1 in CH2Cl2 solution react to give [Pt(OH)Me2(κ3-N,N',N"-L)]Cl, when L = L1 or L2, or [Pt(OH)Me2(κ3-N,N',O-L-H)], when L = L3. The complex [Pt(OH)Me2(κ3-N,N',N"-L2)]Cl decomposed in the presence of air to give the binuclear complex [{PtMe2(2-C5H4NCO2)(μ-OH)}2]. The factors influencing reactivity and mechanism in these reactions are elucidated, and the presence of both a free pyridyl donor (push group) and a free hydroxyl (pull group) is suggested to give a synergy for dioxygen activation by dimethylplatinum(II) complexes. [ABSTRACT FROM AUTHOR]