CO-induced ring-slippage reactions of molybdenocene and tungstenocene carbonyl complexes. Electrochemical and elevated-pressure infrared evidence for an electron-transfer catalysis
Abstract Infrared studies at a CO pressure of 120 bar show (η 5 -C 5 H 5 ) 2 W(CO) to be completely resistant to an excess of CO in the absence of oxidants, but cyclovoltammetric measurements with this complex and with (η 3 -C 5 H 5 )(η 5 -C 5 H 5 )W(CO) 2 in THF solution at 0°C indicate that the ring-slipped dicarbonyl complex is catalytically generated by a one-electron oxidation of the tungstenocene monocarbonyl under CO at ambient pressure. Similar results are found for the reaction of (η 5 -C 5 H 5 ) 2 Mo(CO) with CO.
Iron carbonyls with bulky thiolate ligands: crystal structures of [Fe2(CO)6(μ-SC6H2-2,4,6)2] and (C6H2-2,4,6)2S2
Abstract The reaction of Fe3(CO)12 and bulky thiols HSR (R = C6H2 i Pr 3 -2,4,6; C6H2Me3-2,4,6) in toluene yielded compounds [Fe2(CO)6(μ-SR)2] (R = C6H2 i Pr 3-2,4,6 (1), C6H2Me3-2,4,6 (2)). The substitution of one carbonyl by the phosphine Ph2P(CH2)2Si(OEt)3 in complex 1 afforded {Fe2(CO)5[Ph2P(CH2)2Si(OEt)3](μ-SC6H2 i Pr 3-2,4,6)2} (3). Mononuclear compounds [(η5-C5H5)Fe(CO)2(SC6H2 i Pr 3 -2,4,6)] (4) and {(η5-C5H5)Fe(CO)[Ph2P(CH2)2Si(OEt)3](SC6H2 i Pr 3 -2,4,6)} (5) have also been obtained. Compound 1 has been studied by X-ray diffraction and the structure determined reveals a distorted octahedron geometry around each iron atom and confirms the anti arrangement of R substituents, R = C6H2 i Pr 3 -2,4,6, in the molecule. The preparation of thiol HSC6H2 i Pr 3 -2,4,6 yielded the disulfide (C6H2 i Pr 3 -2,4,6)2S2 as a by-product, whose structure has been solved by X-ray diffraction.
Reactions of Dicyclopentadienyltitanium(III) Compounds with Carbon Monoxide
Reactions of Cp2TiR (R = Cl, C6F5, C6H5, o-CH3C6H4) with CO give two types of products: terminally coordinated adducts, Cp2Ti(R)CO, and insertion products, Cp2TiCOR, i.e. acyl compounds. The acyl ligand is η2-coordinated at the titanium atom. The preparations and properties of the compounds are described.