STEPWISE SYNTHESIS OF OCTAMETHYLFERROCENE-1,1'-DICARBALDEHYDE - PREPARATION OF NEW ELECTRON-DONORS FOR CHARGE-TRANSFER COMPLEXES

A stepwise synthesis of octamethylferrocene-1,1'-dicarbaldehyde (3), s tarting from 3,4-tetramethyl-5-(methoxycarbonyl)cyclopentadiene (7) is described, involving ferrocene formation, ester reduction to the corr esponding bis(hydroxymethyl) derivative 9, and MnO2 oxidation. The ald ehyde 3 readily reacts with different phosphonates derived from sulfur -containing heterocycles in a Wittig-Horner reaction to form new elect ron donors that may be used in the preparation of various charge trans fer complexes. The X-ray crystal structures of ne)methyl]-2,2',3,3',4, 4',5,5'-octamethylferrocene (11a), ne)methyl]-2,2',3,3',4,4',5,5'-octa methylferrocene (11b), ne)methyl]-2,2',3,3',4,4',5,5'-octamethylferroc ene (12a), and and ne)methyl]-2,2',3,3',4,4',5,5'-octamethylferrocene (12c) have been determined. In these compounds the planes of the sulfu r heterocycles are oriented at angles of 60-75 degrees, with respect t o the plane of the respective Cp ring.