Electronic Communication in Binuclear Osmium- and Iridium-Polyhydrides.

Reactions of polyhydrides OsH(PPr) () and IrH(PPr) () with rollover cyclometalated hydride complexes have been investigated in order to explore the influence of a metal center on the MH unit of the other in mixed valence binuclear polyhydrides. Hexahydride activates an -CH bond of the heterocyclic moiety of the trihydride metal-ligand compounds OsH{κ-,-[CRHN-py]}(PPr) (R = H (, Me (), Ph ()). Reactions of and lead to the hexahydrides (PPr)HOs{μ-[κ-,-[CRHN-CHN]-,-κ]}OsH(PPr) (R = H (), Me ()), whereas gives the pentahydride (PPr)HOs{μ-[κ-,-[CHN-C(CH)HN]-,,-κ]}OsH(PPr) (). Pentahydride promotes C-H bond activation of and the iridium-dihydride IrH{κ-,-[CHN-py]}(PPr) () to afford the heterobinuclear pentahydride (PPr)HOs{μ-[κ-,-[CHN-CHN]-,-κ]}IrH(PPr) () and the homobinuclear tetrahydride (PPr)HIr{μ-[κ-,-[CHN-CHN]-,-κ]}IrH(PPr) (), respectively. Complexes - and display HOMO delocalization throughout the metal-heterocycle-metal skeleton. Their sequential oxidation generates mono- and diradicals, which exhibit intervalence charge transfer transitions. This notable ability allows the tuning of the strength of the hydrogen-hydrogen and metal-hydrogen interactions within the MH units.