The potential energy surface (PES) for singlet 1,1-dilithioethene isomers was surveyed carefully using ab initio quantum mechanical methods. The two structures considered in earlier studies, a perpendicular C-2 upsilon form (1) and a planar C-2 upsilon form (2), were found to be transition states. Vibrational frequencies were evaluated for all ten structures investigated through the coupled-cluster method including all single and double excitations with a double-zeta plus polarization basis set (CCSD/DZP). A planar, monobridged lithium, C-s form (4) with a planar tetracoordinate carbon was found to be the lowest lying singlet 1,1-dilithioethene structure. The other minima, a singlet 1,1-dilithioethene planar dibridged C-2 upsilon form (3) and a planar C-2 upsilon complex between vinylidene and lithium dimer (6), are 7.2 and 29.7 kcal/mol higher lying than 4 at CCSD/DZP (+ZPVE), respectively. Remarkably, 3 possess a planar pentacoordinate carbon. The pathway for conversion of 4 to the C2H2Li2 global minimum (7) was found to require only 10 kcal/mol at CCSD/DZP (+ZPVE).