Fig. 2. CAS natural orbitals from CASSCF.

(A) Ground-state CASSCF natural orbitals demonstrating qualitative changes in the Mo-N₂ bonding interactions in select structures along the dissociation trajectory (see orbital occupations in table S4). Orbitals above the black horizontal dashed line are nearly empty (virtual), and below are nearly completely filled (occupied). Arrows mark orbital lineage. Thick dashed arrows between s:10 and s:13 and s:13 and s:16 indicate crossing of an occupied orbital character (N₂ π) into the virtual space or of a virtual (N₂ π*) into the occupied space. Isosurface value: 0.02 atomic units (au); the Au₁₀Mo-embedded cluster model + N₂ are shown (see Fig. 1A for structural legend). (B) Schematic representation of the bonding orbital interactions between Mo 4d and N₂ π or π* in s:6, s:13, and s:16.