COMPARISON OF THE PROPERTIES OF POLYMETHYL-1,1'-DIHETEROFERROCENES OF THE GROUP 15 ELEMENTS

2,2',5,5'-Tetramethyl-1,1'-diheteroferrocenes, (C4H2-alpha-Me(2)X)(2)Fe, and 2,2',3,3',4,4',5,5'-octamethyl-1,1'-diheteroferrocenes, (C(4)Me(4)X)(2)Fe, where X = P, As, Sb, and Bi, have been prepared from the reactions of the corresponding 1-phenylheteroles with lithium followed by FeCl2. The redox chemistry has been explored using cyclic voltammetry. The redox E(1/2)(0/+) values of both series of diheteroferrocenes correlate well with the ionization potentials of the free atoms X = P, As, Sb, and Bi. The 3,3',4,4'-tetramethyl-1,1'-diheteroferrocenes (C4H2-beta-Me(2)X)(2)Fe, where X = P, As, and Sb, have been prepared in a similar manner. These compounds undergo electrophilic isotopic exchange of the ring hydrogen atoms on treatment with trifluoroacetic acid-dr at rates that increase with the atomic number of the heteroatom