A versatile strategy for the formation of hydride-bridged actinide–iridium multimetallics

Reaction of the potassium pentamethylcyclopentadienyl iridate tris-hydride K[IrCp*H(3)] with UCl(4) and ThCl(4)(DME)(2) led to the complete replacement of the halide ligands to generate multimetallic complexes U{(μ-H)(3)IrCp*}(4) (1) and Th{[(μ-H(2))(H)IrCp*](2)[(μ-H)(3)IrCp*](2)} (2), respectively. These analogues feature a significant discrepancy in hydride bonding modes; 1 contains twelve bridging hydrides while 2 contains ten bridging hydrides and two terminal, Ir-bound hydrides. Use of a U(iii) starting material, UI(3)(1,4-dioxane)(1.5), resulted in the octanuclear complex {U[(μ(2)-H(3))IrCp*](2)[(μ(3)-H(2))IrCp*]}(2) (3). Computational studies indicate significant bonding character between U/Th and Ir in 1 and 2, with f-orbital involvement in the singly-occupied molecular orbitals of the uranium species 1. In addition, these studies attribute the variation in hydride bonding between 1 and 2 to differences in dispersion effects.