Density functional theory shows that the dizincocenes Zn2(C5X5)2 (X = H, F) have singlet coaxial structures with two (η5-C5X5)Zn units linked by a Zn–Zn single bond. However, the low-energy M2(C5H5)2 (M = Cu–Fe) structures have perpendicular configurations with bridging C5H5 ligands.