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.