Synthesis and Characterization of Dinuclear Rare Earth Complexes Bearing N-heterocyclic Olefin Moieties

The oxygen-bridged dinuclear rare earth complexes (Ln = Nd (1), Y (2)) bearing N-heterocyclic olefin moieties were synthesized by treating the imidazolidinium salt [SIMes-H]Br with potassium amide and rare earth bis(trimethylsilyl)amides. Complex 1 was characterized by X-ray diffraction analysis and complex 2 was characterized by H-1 NMR spectroscopy. Both complexes were characterized by elemental analysis. Crystal data of complex 1: C74H138O2N8Si8Nd2, M-r = 1685.12, orthorhombic, space group Pbca, a = 25.1105(7), b = 11.9188(2), c = 29.6151(7) angstrom, V= 8863.4(4) angstrom(3), Z = 4, D-c = 1.263 g.cm(-3), mu = 1.311 mm(-1), F(000) = 3544, the final R = 0.0418 and wR = 0.0770 for all data. The ring-opening of tetrahydrofuran molecule was proven, the possible mechanism for the formation of N-heterocyclic olefin (NHO)-rare earth complexes was speculated and the electronic and steric properties of SIMes and rare earth amides were discussed. This work provides a better understanding of N-heterocyclic carbene rare earth chemistry.