TERMETALLOCENES

Selected properties of seven termetallocenes with the metal sequences Fe-Co-Fe, Co-Ru-Co, Co-Os-Co, Co-Fe-Co, Rh-Fe-Rh, Ni-Fe-Ni and Rh-Fe-C o, synthesized by different published routes are described and compare d with the parent compound terferrocene. The crystal structure of the hexafluorophosphate of the l,1'-dicobaltocenyl-ruthenocene dication wa s determined by X-ray diffraction: crystals are monoclinic, space grou p C2/c, a = 10.378(2), b = 14.070(2), c = 24.841(2) angstrom, beta = 9 2.02(1)-degrees, V = 3625 angstrom3, Z = 8/2. This is the first struct ure determination of a termetallocene and the molecular alignment is u nprecedented. The electrochemical behaviour of all bi-heterometallic s ystems was supplemented by unpublished CV measurements and compared wi th 1,1'-ferrocenediyl-bis(fulvalene)diiron, a formal quinquemetallocen e. In addition, the elusive H-1 NMR of rhc-fec-coc++ is presented.