Presentation of Results
A. Use your infrared data, and also the n.m.r. data supplied, to deduce the formula of the final product.
B. Summarise the principal spectroscopic evidence for your conclusion.
C. Write down the reaction sequence and discuss it in terms of the 18-electron rule. How might the mechanism of the final step be investigated ?
D. Produce written answers to the questions below:
(1) What do CO and Ph3P have in common as ligands ?
(2) In ketones the C-O stretching frequency lies in the range 1700-1750 cm-1. Why do you think the equivalent C-O strecyh in the Ph3P adduct prepared in the above experiment occurs at a much lower frequency ?
(3) Why is the compound [Fe(-C5H5)(CO)2]2 diamagnetic ?
(4) The methyl complex Fe(-C5H5)(CO)2CH3, which may be prepared from the Chloride Fe(-C5H5)(CO)2Cl, is both thermally stable and comparatively inert to oxidation by O2. However, the methyl derivitive of the stable compound FeCl3 is not isolable and is thought to be explosively unstable. Why is this ?
(5) THere are known mono or binuclear compounds with the general formula Mx(-C5H5)y(CO)z, where M = Ti, Zr, V, Nb, Ta, Mn, Re, Co, Rh, Ir. Predict the stoichiometry and structure of such compounds assuming that they all obey the 18-electron rule. Also, predict the structure of the tetramer [Fe(-C5H5)(CO)4] (a cubane-type compound).
(6) Write out a plausible mechanism for the formation of a propanal from ethene, hydrogen and carbon monoxide, suing CoCl2 as catalyst. This is the hydroformylation process.
(7) Predict the structures (?) of the following reactions:
(a) CO + Mn(CO)5CH3 --Change in pressure-> ?
(b) CH3COCl + Na[Mn(CO)5] --THF-> ? + NaCl
? + NaCl --80° in vacuo-> ?1 + ?2
© Copyright 1997 Oxford University