Electronic Properties of Unprecedented Bridging Organoimido-Substituted Hexamolybdate: New Insights from Density Functional Theory Study

The organoimido functionalization of polyoxometalates (POMs) has drawn tremendous attention due to particular merits in fabricating POM-based hybrid materials with finely tunable properties. The electronic properties, orbital and bonding characters of unprecedented bridging organoimido-substituted hexamolybdate are investigated using density functional theory methods. Among the organoimido-bridged hexamolybdates, [Mo6O16(2,6-Me-2-NC6H3)(2)(mu(2)-2,6-Me-2-NC6H3)](2-) (3-Ar-l), which features two terminal and one bridging organoimido ligand, is more favorable. The calculations confirm that the three-center (3c). pi bond originates From the coplanarity of bridging nitrogen atom with two Mo atoms and the hybridization of bridging nitrogen. The 3c bond stabilizes the organoimido-bridged anion 3-Ar-l. Compared with cis-bifunctionalized organoimido derivative [Mo6O17(2,6-Me-2-NC6H3)(2)](2-) (2-Ar), the bonding interaction between terminal organoimido ligand and hexamolybdate cluster. in 3-Ar-l is strengthened by the bridging organoimido. The results are in good agreement with thin analysis of the Wiberg bond index of the Mo-N bond. The organoimido segment modifies the occupied molecular orbitals of organoimido hexamolybdates. The unoccupied molecular orbitals in 3-Ar-l are largely nonbonding O-p and Mo-d orbitals in character, which resemble those of 2-Ar.