Molecular Thorium Trihydrido Clusters Stabilized by Cyclopentadienyl Ligands. Issue 28 (7th May 2020) - Chen, Runhai
Abstract: Hydrogenolysis of alkyl‐substituted cyclopentadienyl (Cp R ) ligated thorium tribenzyl complexes [(Cp R )Th(p‐CH2 ‐C6 H4 ‐Me)3 ] (1 –6 ) afforded the first examples of molecular thorium trihydrido complexes [(Cp R )Th(μ‐H)3 ]n (Cp R =C5 H2 ( t Bu)3 or C5 H2 (SiMe3 )3, n=5; C5 Me4 SiMe3, n=6; C5 Me5, n=7; C5 Me4 H, n=8; 7 –10 and 12 ) and [(Cp # )12 Th13 H40 ] (Cp # =C5 H4 SiMe3 ; 13 ). The nuclearity of the metal hydride clusters depends on the steric profile of the cyclopentadienyl ligands. The hydrogenolysis intermediate, tetra‐nuclear octahydrido thorium dibenzylidene complex [(Cp ttt )Th(μ‐H)2 ]4 (μ‐p‐CH‐C6 H4 ‐Me)2 (Cp ttt =C5 H2 ( t Bu)3 ) (11 ) was also isolated. All of the complexes were characterized by NMR spectroscopy and single‐crystal X‐ray analysis. Hydride positions in [(Cp Me4 )Th(μ‐H)3 ]8 (Cp Me4 =C5 Me4 H) were further precisely confirmed by single‐crystal neutron diffraction. DFT calculations strengthen the experimental assignment of the hydride positions in the complexes 7 to 12 . Abstract : Molecular actinide trihydrido complexes, [(Cp R )Th(μ‐H)3 ] n ( n =5, 6, 7, 8) were isolated and structurally characterized. The nuclearity of each metal cluster increases with the decreasing steric demand of the alkyl‐substituted cyclopentadienyl ligand (Cp R ). Hydride positions in complex [(Cp Me4 )ThH3 ]8 were verified by single‐crystal neutron diffraction (Th green, H red, Cp Me4 gray).