The compounds cis-(η5-C5Me5)Re(CO)2Me2 and trans-(η5-C5Me5)Re(CO)2Et2 were prepared by alkylation of cis-(η5-C5Me5)Re(CO)2Cl2 using the corresponding organocopper (RCu). Photolysis of cis(η5-C5Me5)Re(CO)2Me2 in frozen toluene-d8 readily produces the trans-(η5-C5Me5)Re(CO)2Me2. All the compounds were characterized by spectroscopy and analyses, and the stereochemistry assigned from examination of ν(CO) IR intensities; additionally trans-(η5-C5Me5)Re(CO)2Et2 was studied by X-ray crystallography. Crystal data: monoclinic P21/m, a = 8.034(8) Å, b = 11.991(8) Å, c = 8.69(2) Å, β = 91.38°, V = 837(2) Å3, Z = 4, λ(Mo Kα) = 0.7107 Å, RF = 0.0285 and wR1 = 0.071 for 1670 measured reflections with 5 < 2θ < 50°.
- Crystal structure