A Synthetic Route to Alkyl−PtIII Dinuclear Complexes from Olefins and Its Implication on the Olefin Oxidation Catalyzed by Amidate-Bridged PtIII Dinuclear Complexes

• Published in: Journal of the American Chemical Society Vol. 120; no. 12; pp. 2900 - 2907
• Main Authors: Matsumoto, Kazuko, Nagai, Yuji, Matsunami, Jun, Mizuno, Kazuhiro, Abe, Takeya, Somazawa, Ryosuke, Kinoshita, Jun, Shimura, Hideo
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.04.1998
• DOI: 10.1021/ja971129k
• ISSN: 0002-7863

Amidate-bridged PtIII dinuclear complexes [Pt2(NH3)4(Am)2(H2O)2]4+ (Am = amidate ligand) catalyze oxidation of olefins in acidic aqueous solution. Linear olefins are oxidized to ketones, whereas cyclic olefins are oxidized to epoxides. GC−MS analysis of the oxidation products obtained from the reaction in H2 18O showed that the oxygen atoms in the products are exclusively from water, suggesting that the reaction mechanism is basically similar to that of the Wacker reaction. In accordance with this mechanism, pivalamidate-bridged PtIII complex [PtIII 2(NH3)4((CH3)3CCONH)2(H2O)2]4+ has been found to react with olefins to give alkyl complexes. Reactions with 4-penten-1-ol and ethylene glycol vinyl ether in acidic aqueous solution gave and [PtIII 2(NH3)4((CH3)3CCONH)2(CH2CHO)](NO3)3·H2O (9), respectively. The two compounds have been structurally confirmed by X-ray diffraction analysis and 1H, 13C, and 195Pt NMR spectroscopy. The 1H NMR of 9 shows that both π- and σ-complexes exist in equilibrium in D2O, although the X-ray structure is close to the σ-complex. High electrophilicity of the α-carbon atoms of the compounds has been shown in the reactions with OH-. The above reactions with olefins can be a general route to prepare dimeric PtIII−alkyl complexes.