Stepwise syntheses of tri- and tetraphosphaporphyrinogens.

A double ring-expansion methodology allows the stepwise synthesis of tri- and tetra-phosphaporhyrinogens. Structural and calculational methods reveal extended delocalisation about their phospholide centres.

Mechanism of the dehydrogenative silylation of alcohols catalyzed by cationic gold complexes: an experimental and theoretical study.

The catalytic activity both of cationic [(XDPP)Au][X] (XDPP = bis-2,5-diphenylphosphole xantphos X = BF(4)) and of the isolated gold hydride complex [(XDPP)(2)Au(2)H][OTf] in the dehydrogenative silylation process is presented. A parallel theoretical study using density functional theory revealed a mechanism involving the counter anion as a co-catalyst, which was experimentally confirmed by testing various counterions (X = OTf, NTf(2), PF(6)). Finally, a "Au(2)H(+)" species was determined as the intermediate during the catalytic cycle, which correlates well with the experimental findings on the first example of catalytic activity of an isolated "Au-H" complex.