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Bis-pinacolatodiboron reacts with [small alpha],[small beta]-unsaturated carbonyl compounds to give 1,4- and unprecedented 3,4-additions in the presence of a second generation Pt(0) catalyst at ambient temperature.

The use of alkenes and bidentate N-ligands in the platinum(0)-catalyzed hydrosilylation of styrene with triethylsilane has been evaluated. A number of bidentate N-ligands, phen, bpy, dafo, and phenyl-bian, were tested at various reaction temperatures using in situ formed catalysts with [Pt(nbe) 3 ] as a precursor. The main conclusions are: (i) ligands, such as phen, which form stable platinum(0) complexes, give lower catalytic activities compared to the ligands which form less stable complexes; (ii) a small ligand effect is observed with dafo and phenyl-bian compared to [Pt(nbe) 3 ], the precursor complex, displaying the lability of these ligands. The complex [Pt(nbe) 3 ], that only has labile alkene ligands, is an active catalyst at low temperatures. At higher temperatures, the catalyst is no longer stable and a decrease

A zerovalent platinum(carbene) complex with two monoalkene ligands, which is able to activate C-H bonds of imidazolium salts at room temperature to yield isolable hydrido platinum(II) bis(carbene) compounds, has been synthesised for the first time.

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Organo-boron compounds S 0040Platinum Catalyzed 3,4-and 1,4-Diboration of α,β-Unsaturated Carbonyl Compounds Using Bis-Pinacolatodiboron. -Bis-pinacolatodiboron (II) reacts with α,β-unsaturated carbonyl compounds (I) to give 1,4-and unprecedented 3,4-additions in the presence of a second generation Pt-catalyst. -(BELL, N. J.; COX, A. J.; CAMERON, N. R.; EVANS, J. S. O.; MARDER*, T. B.; DUIN, M. A.; ELSEVIER, C. J.; BAUCHEREL, X.; TULLOCH, A. A. D.; TOOZE, R. P.; Chem. Commun.