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.