Pentamethylcyclopentadienyl-rhodium and -iridium complexes. Part 20. Rhodium complexes of co-ordinated hydrazines

Abstract

The monoadducts [Rh(C₅Me₅)X₂(NH₂NR¹R²)] are formed by reaction of NH₂NR¹R² with [Rh₂(C₅Me₅)₂X₄](1)(R¹= R²= Me, X = Cl, Br, or I; R¹= H, R²= Ph, C₆F₅, or p-MeC₆H₄, X = Cl; and R¹= Me, R²= Ph, X = Cl); the bis complexes [Rh(C₆Me₅)Cl(NH₂NHR)₂][PF₆](R = Ph or p-MeC₆H₄) are also obtained. All these complexes are very labile and lose the hydrazine readily. Methylhydrazine forms a 1 : 2 adduct with (1), [Rh₂(C₅Me₅)₂X₄(NH₂NHMe)], the n.m.r. spectra of which shows the existence of an exchange process. This is proposed to be due to an equilibrium between the neutral monohydrazine-bridged species [{Rh(C₅Me₅)X₂}₂(NH₂NHMe)] and ionic species [{Rh(C₅Me₅)X(NH₂NHMe)}]₂]²⁺ 2[Rh(C₅Me₅)X₃]^–. The reaction of (1; X = Cl) with a stoicheiometric amount of N₂H₄ eventually leads to [Rh(C₅Me₅)(N₂H₄)₃]Cl₂; analogous ammine complexes [Rh(C₅Me₅)(NH₃)₃]²⁺ have also been obtained.