Electronic Structure of [U2(μ2-N2)(η5-C5Me5)2(η8-C8H4(SiPri3)2)2]

Density functional calculations on the model compound [U-2(mu(2) -N-2)(eta(5)-C5H5)(2)(eta(8)-C8H6)(2)] support the formulation of the recently characterized dinitrogen complex [U-2(mu(2) - N-2)(eta(5)-C-5-Me-5)(2)(eta(8)-C8H4(SiPr3i)(2))(2)] as containing two U(IV) f(2) centers bridged by a N-2(2-) ligand. The N-N distance found experimentally (1.232 Angstrom) can be modeled only in a geometry optimization by a non-aufbau occupation of the orbitals. Though both N(2)pi(g) orbitals overlap significantly with U 5f orbitals, only the more stable of the two is occupied in the optimum calculation.