Differences in ligand strength and coordination geometry also play an important role in governing Co-Co σ-bonding. Like the dicobalt compounds in this study, both N4 and D10, feature Co centers in an approximately trigonal bipyramidal environment, which distort towards octahedral symmetry due to the neighboring Co in the equatorial plane (Figures ). In N4 each Co has H (1.660 Å) and Si (2.243 Å) axial ligands while the equatorial ligands are C (1.960 Å) and two H's (1.650 Å and 1.666 Å). The Co 3𝑑 𝑥𝑦 orbitals are significantly destabilized by overlap with bridging hydrides in the equatorial plane and are thus vacant. Like 3 and 4, the 3𝑑 𝑥 2 -𝑦 2 orbitals of each Co overlap, allowing a single Co-Co σ-bond to form. A contour plot of this occupied MO is visualized in Figure , showing symmetry consistent with Co 3𝑑 𝑥 2 -𝑦 2 overlap and minimal multicenter character. This MO is composed of 80.8% Co 3d and only 0.6% Si 3p character, consistent with a direct Co-Co interaction. The difference in Co-Co bond order between N4 (0.78) and 3 (0.31) likely results from differences in coordination geometry, which may allow for greater orbital overlap in N4 than in 3. This difference also highlights that metalmetal bonding is best described by a continuous extent of interaction, rather than a discrete whole number of metal-metal bonds.