Dimeric Ru(II) complexes Ru2(CO)4L2X4 (L = CO or PPh3; X = Cl or Br) have been found to catalyze the hydrolysis of silanes to produce hydrogen gas and silanols with turnover numbers in excess of 104 at room temperature. Deuteration and mass spectrometric studies have established that the hydrogen gas originates from one hydrogen atom from water and the other from silane. Ruthenium hydride intermediates have been detected in the NMR spectrum during the early stage of the reaction, while the FTIR spectra of more stable complexes such as Ru(CO)2(PPh3)(THF)Br2 and Ru(CO)2(PPh3)2(H)Br have been recorded upon completion of catalysis. A mechanism has been proposed to account for the ruthenium-catalyzed silane hydrolysis based on the experimental data.

The addition of carboxylic acids onto terminal alkynes was catalyzed by mononuclear ruthenium(0) complexes to give enol esters in high yields. By using ligands with different electronic properties, product selectivity was achieved. E‐enol esters were preferentially produced when tricarbonyl(η4‐diene)ruthenium complexes were used; while geminal enol esters were produced when tricarbonylbis(phosphane)ruthenium complexes were used.

The 532 or 355 nm laser-induced photoisomerization of allylic alcohols to aldehydes catalyzed by [Fe(3)(CO)(12)] or [Fe(CO)(4)PPh(3)] in hexane was investigated. The Fourier transform infrared (FTIR) absorption spectra of iron-carbonyl intermediate species such as [Fe(CO)(5)], [Fe(CO)(4)(R-C(3)H(4)OH)], and more importantly the pi-allyl iron-carbonyl hydride species [FeH(CO)(3)(R-C(3)H(3)OH)] (R=H, Me, Ph) were recorded during the catalytic process using [Fe(3)(CO)(12)] as the catalytic precursor. When [Fe(CO)(4)PPh(3)] was photolyzed with 355 nm, [FeH(CO)(3)(R-C(3)H(3)OH)] was also generated indicating the common occurrence of the species in these two systems. The pi-allyl hydride species is long believed to be a key intermediates and its detection here lends support to the pi-allyl mechanism of the photoisomerization of allyl alcohols.

No abstract

No abstract