To explore the coordination chemistry of dibenzopentalene dianion, reactions of two dilithium dibenzopentalenides having different silyl substituents with Cr(CO)3 (CH3 CN)3 were investigated. The products were unexpected anionic complexes, [Li(Et2 O)]+ [Cr(η5 -9-hydrodibenzopentalenyl)(CO)3 ]- . The proton at the 9-position is derived from Cr(CO)3 (CH3 CN)3 , as evidenced by the use of Cr(CO)3 (CD3 CN)3 . The X-ray diffraction analysis revealed that the chromium is coordinated by an anionic five-membered ring of the pentalene skeleton, and the lithium atom is coordinated by oxygen atoms of the carbonyl groups. The complexes form a dimer or a cage-like tetramer via carbonyl-lithium interactions, depending on the bulk of the silyl groups. The cubic tetramer appears to retain its cage structure in nonpolar solvents such as benzene.