Reaction of ferrocene and 3,3',4,4'-tetramethyl-1,1'-diphosphaferrocene wit
h diketene in the presence of BF3. Et2O affords the BF2 chelates of acetoac
etylated metallocenes 2a,b. The crystal structures of these complexes have
been determined by X-ray diffraction. When the reaction is carried out in t
he presence of AlCl3, metallocene 1,3-diketones 3a,b are formed.