Synthesis and molecular structure of (η5-pentamethyl-cyclopentadienyl) (η5-cyclopentadienyl) hexacarbonyl molybdenum tungsten

The metathesis reaction of CP*(CO)(3)MoBr and NaW(CO)(3)CP produced CP*(CO)(3)MO-W(CO)(3)CP (1), featuring an unsupported Mo-W bond. Exposure of solutions of 1 to light leads to the quantitative formation of the corresponding homometallic dimers. In the solid state, the title complex exhibits an anti-arrangement of the eta(5)-cyclopentadienyl and the eta(5)-pentamethyl-cyclopentadienyl ligands and six terminal carbonyls. Comparison to corresponding complexes of molybdenum and tungsten reveals that the Mo-W distance is dictated by the presence of a Cp and a Cp* ligand. This is the first time that an unsupported Mo-W single bond distance is reported. (C) 2004 Elsevier B.V. All rights reserved.