Synthesis of a heterobimetallic actinide nitride and an analysis of its bonding

Reaction of [K(DME)][Th{N(R)(SiMe2CH2)}(2)(NR2)] (R = SiMe3) with 1 equiv. of [U(NR2)(3)(NH2)] (1) in THF, in the presence of 18-crown-6, results in formation of a bridged uranium-thorium nitride complex, [K(18-crown-6)(THF)(2)][(NR2)(3)U-IV(mu-N)Th-IV(NR2)(3)] (2), which can be isolated in 48% yield after work-up. Complex 2 is the first isolable molecular mixed-actinide nitride complex. Also formed in the reaction is the methylene-bridged mixed-actinide nitride, [K(18-crown-6)][K(18-crown-6)(Et2O)(2)][(NR2)(2)U(mu-N)(mu-kappa(2)-C,N-CH2SiMe2NR)Th(NR2)(2)](2) (3), which can be isolated in 34% yield after work-up. Complex 3 is likely generated by deprotonation of a methyl group in 2 by [NR2](-), yielding the new mu-CH2 moiety and HNR2. Reaction of 2 with 0.5 equiv. of I-2 results in formation of a U-V/Th(IV)bridged nitride, [(NR2)(3)U-V(mu-N) Th-IV(NR2)(3)] (4), which can be isolated in 42% yield after work-up. The electronic structure of 4 was analyzed with EPR spectroscopy, SQUID magnetometry, and NIR-visible spectroscopy. This analysis demonstrated that the energies of 5f orbitals of 4 are largely determined by the strong ligand field exerted by the nitride ligand.

Automated summary

In this study, two mixed-actinide nitride complexes were successfully synthesized and further characterized using various analytical methods, providing important data support for a deeper understanding of the properties and structures of mixed-metal nitride complexes.