The structures for the binuclear Cp2Ti2(CO)(n) derivatives (Cp = eta(5)-C5H5; n = 8, 7, 6, 5, 4, 3, 2) have been optimized using density functional theory. Furthermore, the thermodynamics of CO dissociation, disproportionation into Cp2Ti2(CO)(n+1) + Cp2Ti(2)(CO)(n-1), and dissociation into mononuclear fragments of these Cp2Ti2(CO)(n) derivatives have been studied. An unbridged Cp2Ti2(CO)(8) Structure with a long similar to 3.9 angstrom Ti-Ti bond is found. As expected from the long Ti-Ti bond, the predicted dissociation energy of this dimer into CpTi(CO)(4) fragments is relatively low at 7 +/- 3 kcal/mol. The lowest energy Cp2Ti2(CO)(6) structure has two CpTi(CO)(3) units linked by a formal similar to 2.8 A Ti Ti triple bond and thus is the next member of the M M triply bonded series Cp2V2(CO)(5), Cp2Cr2(CO)(4), Cp2Mn2(CO)(3), all three of which are stable compounds. The lowest energy structures of Cp2Ti2(CO)(7), CP2Ti2(CO)(5), and CP2Ti2(CO)(4) all contain one or two four-electron donor bridging eta(2)-mu-CO groups. However, they are not likely to be stable molecules since their disproportionation energies into Cp2Ti2(CO)(n+1) + Cp2Ti2(CO)(n-1) are either nearly thermoneutral (n = 5) or exothermic (n = 7 and 4). The lowest energy structure of Cp2Ti2(CO)(3), in which all three carbonyl groups are four-electron donor eta(2)-mu-CO groups bridging a similar to 3.05 angstrom formal Ti-Ti single bond, is a promising synthetic target since it is thermodynamically stable with respect to both CO dissociation and disproportionation into Cp2Ti2(CO)(4) + Cp2Ti2-(CO)(2). In the lowest energy Cp2Ti2(CO)(2) structure both carbonyl groups are four-electron donor eta(2)-mu-CO groups bridging a formal 2.74 angstrom Ti Ti triple bond. These low energy Cp2Ti2(CO), (n = 3, 2) structures have only a 16-electron titanium configuration rather than the usually favorable 18-electron configuration for metal carbonyl complexes,