The electron transfer chain catalyzed redox reaction via the intramol. disproportionation of binuclear carbonylfulvene complexes in the presence of PR3 to give the title compds. is described. Thus, [FeICp(C6Me6)]-catalyzed intramol. disproportionation of carbonylfulvene complexes I (M1 = Mo, W, Fe, Ru; M2 = Mo, W; n = 2, 3) in THF/DME gave fulvalene-bridged heterodinuclear complexes II. The crystal structure of II (M1 = Fe, n = 2, R = Me) was detd.