MetalAzo and metalimine compounds : III. The influence of metal basicity on the cleavage of C:H bonds by Rh I and Ir I

Abstract

From the reaction of R′X=NR (X = N or CH) with [MCl(C 8H 14) 2| in the presence of CO or PR 3. σ( N)- coordinated complexes cis-RhCl(CO) 2(R′CH=NR) and cyclometallated complexes MHCl(L′)(PR 3) 2 [′ is cyclometallated R′X=NR; R = Ph or Cy when M = Ir; R = Cy when M = Rh] were isolated. The ease of CH bond breaking by M 1 appears to be strongly dependent on the basic properties of M I, and decreases as follows: aromatic CH > olefinic CH > aliphatic CH. On the basis of the chemical and structural information, the metallation can be explained in terms of Pearson's symmetry rules for chemical reactions. For the cyclometallated azo compounds, ν(N=N) shows resonance enhancement ion the Raman spectra, and appears to be very sensitive to the basicity of M I in the reactant system.