Beschreibung:
<jats:p>The new trifluoroethoxo phosphine complexes [Cp2M(?1-dppe)(CF3CH2O)]+ and
[Cp2(CF3CH2O)M(?-dppe)MCp2(CF3CH2O)]2+ (M = Mo or W, Cp = ?-C5H5 and dppe =
Ph2PCH2CH2PPh2) have been prepared by reaction of cationic di-?-hydroxo
dinuclear complex of molybdenocene or tungstenocene [Cp2M(?-OH)2MCp2]2+ with
dppe. From the 1H and 31P NMR data, the configurations of the products could
be assigned. Furtheremore, X-ray crystallography was used to definitively
identify one of the product [Cp2(CF3CH2O)Mo(?-dppe)MoCp2(CF3CH2O)]2+, which
crystallizes in space group P21/c(#14) with a = 12.230(5) ?, b = 11.149(5)
?, c = 28.966(7) ?, ? = 101.07(3)?, V = 3876(2) ?3, and Z = 2. It was
ascertained that the amount of dppe added to the reaction mixture could
influence the product distribution. A mechanism involving initial
replacement of the hydroxo ligand by the alkoxo group followed by
nucleophilic attack of the phosphine is proposed on the basis of the
reaction profile.</jats:p>