Transition-metal nitrosyl compounds. Part 13. Some reactions of dinitrosylbis(triphenylphosphine)-cobalt, -rhodium, and -iridium cations
Abstract
The dinitrosyl cations [M(NO)2(PPh3)2]+(M = Co, Rh, or Ir) have been prepared and some of their reactions examined. A 31P n.m.r. study of the cations of Rh and Ir suggests that phosphine exchange is primarly via an associative process; evidence is also presented to suggest that exchange with the Co proceeds via a predominantly dissociative mechanism. Reaction of [Rh(NO)2(PPh3)2]+ or [Ir(NO)2(PPh3)2]+ with tertiary phosphines(L′) gives [M(NO)(PPh3)3] and [NO]+when L′= PPh3 but [ML′4]+ when L′= a less bulky phosphine. In contrast, [Co(NO)2(PPh3)2][PF6] gives [Co(NO)2L′2][PF6]. A rationale which accounts for this variation in reactivity is offered. The salt [Co(NO)2(PPh3)2][PF6] reacts with Cl–, Br–, or I–(X–) to provide [Co(NO)2(PPh3)X]; [Ir(NO)2(PPh3)2][PF6] reacts with HCl to form [Ir(NO)(PPh3)2Cl2]. Reaction of [Ir(NO)2(PPh3)2][PF6] with 2,2′-bipyridyl produces [Ir(NO)(PPh3)2(bipy)]2+ and N2O. Reduction of [M(NO)2(PPh3)2]+ by Na[BH4] in tetrahydrofuran and in the presence of PPh3 produces [M(NO)(PPh3)3] and ammonia.
Please wait while we load your content...
