A series of tetranuclear compounds consisting of two {Mo-2[(m-CF3C6H4)NC(H)N(m-CF3C6H4)](3)}(n+) moieties linked by two OH-or two O2- ions has been characterized. Abbreviating the dimolybdenum plus three spectator bridging ligands as [Mo-2], the following three compounds have been made-[Mo-2](mu-OH)(2)[Mo-2] (1), [Mo-2](mu-O)(2)[Mo-2] (2), and {[Mo-2](mu-O)(2)[Mo-2]}SbF6 (3). Compound 1, which is diamagnetic and contains quadruply bonded Mo-2(4+) units, is converted to diamagnetic 2 by oxidation with O-2. Compound 2, which has Mo-2(5+) units, is oxidized by NOSbF6 to 3 which has a rare Mo-2(5.5+) core and an odd electron delocalized over the two dimolybdenum units.