The triple-decker sandwich compound trans-Cp2V2(eta(6):eta(6)-mu-C6H6) has been synthesized, as well as "slipped" sandwich compounds of the type trans-Cp2Co2(eta(4):eta(4)-mu-arene) and the cis-Cp2Fe2(eta(4):eta(4)-mu-C6R6) derivatives with an Fe-Fe bond (Cp = eta(5)-cyclopentadienyl). Theoretical studies show that the symmetrical triple-decker sandwich structures trans-Cp2M2(eta(6):eta(6)-mu-C6H6) are the global minima for M = Ti, V, and Mn but lie similar to 10 kcal/mol above the global minimum for M = Cr. The nonbonding M center dot center dot center dot M distances and spin states in these triple decker sandwich compounds can be related to the occupancies of the frontier bonding molecular orbitals. The global minimum for the chromium derivative is a singlet spin state cis-Cp2Cr2(eta(4):eta(4)-mu-C6H6) structure with a very short CrCr distance of 2.06 angstrom, suggesting a formal quadruple bond. A triplet state cis-Cp2Cr2(eta(4):eta(4)-mu-C6H6) structure with a predicted Cr Cr distance of 2.26 angstrom lies only similar to 3 kcal/mol above this global minimum. For the later transition metals the global minima are predicted to be cis-Cp2M2(eta(6):eta(6)-mu-C6H6) structures with a metal-metal bond, rather than triple decker sandwiches. These include singlet cis-Cp2Fe2(eta(4): eta(4)-mu-C6H6) with a predicted Fe=Fe double bond distance of 2.43 angstrom, singlet cis-Cp2Co2(eta(3):eta(3)-mu C6H6) with a predicted Co-Co single bond distance of 2.59 angstrom, and triplet cis-Cp2Ni2(eta(3):eta(3)-mu-C6H6) with a predicted Ni-Ni distance of 2.71 angstrom.