NOVEL RHODATE AND IRIDATE COMPLEXES CONTAINING C,N CHELATING ARYLAMINE LIGAND SYSTEMS

The synthesis is described of a series of new iridate and rhodate comp lexes Li(L-C,N)2M(cod) (M = Rh, Ir; cod = cycloocta-1,5-diene) contain ing the ortho-chelating, mono-anionic, arylamine ligands L = C6H4CH2NR 2-2 (R = Me, Et), C6H3CH2NMe2-2-Me-5, C6H4CH(Me)NMe2-(R)-2 or C6H4CH2N Me(tBu)-2. The synthetic procedure for the -ate complexes from [MCI(co d)]2 depends on the solubility of the starting aryllithium compound in benzene-an indirect effect of the bulky organic group on the N-donor atom. All the -ate complexes are formed diastereoselectively (and in t he case of C6H4CH(Me)NMe2-(R)-2, enantioselectively). H-1 and C-13 NMR spectroscopies show the -ate complexes to be monomeric, heterobimetal lic species. The C-13 NMR data show clearly that C(ipso) is bridging b etween the late transition metal and the lithium centre. Consequently, this C(ipso) atom is chiral, and its configuration is stabilized by i ntramolecular coordination of the N-donor atom of the ortho-amine subs tituent. The -ate complexes are fluxional with differences in fluxiona lity (which involve N-dissociation/association, pyramidal inversion at N and rotation around the C(benzyl)-N bond) that can be attributed to differences in the bulk of the groups on the nitrogen atom.