Researchers of Research Initiative for Green Chemical Process, AIST has discovered a new oxidation state , VI, for a transition metal element "palladium" for the first time. Palladium forms one of the most versatile transition metal catalysts for the transformation of organic compounds as well as for the vehicle exhaust gas treatment. Palladium generally prefer lower oxidation states such as 0 and II. The highest oxidation state so far known for palladium was IV.

The researchers discovered the Pd(VI) complexes in the course of their research on the development of new synthetic methods for silicon based polymeric materials. They used transition metal catalysts such as platinum, palladium, and nickel for the transformation of silicon compounds. It was found that these metals formed stable high oxidation states such as III and IV when they were bound to silicon atoms. The Pd(VI) complexes were prepared from three molecules of simple Pd(II) complexes with two silicon atoms. The structure of Pd(VI) complexes were confirmed by X-ray structure analysis.

The discovery of a new oxidation state for palladium will lead to a new area of research for palladium as well as for related transition metals. It will help deeper understandings of catalytic processes and the development of novel catalytic reactions.

The results of this research were published in the journal Sicence (January 11, Vol 295, page 308, 2002)