Novel five-co-ordinate diorganorhodium compounds. X-ray structure of bis-ortho-chelated [RhIII(Me)I{C6H3(CH2NMe2)2-2,6}]

Abstract

Compounds of the type [Rh^III(R)X{C₆H₃(CH₂NMe₂)₂-2,6}] have been synthesized by (i) oxidative addition of Mel (80% yield) or Etl (minor product) to [Rh^I{C₆H₃(CH₂NMe₂)₂-2,6}(cod)](cod = cyclo-octa-1,5-diene); (ii) reaction of [Rh^IIICl(acac){C₆H₃(CH₂NMe₂)₂-2,6}](acac = acetylacetonate) with either AlMe₃, AlEt₃, or LiMe–Lil; (iii) metathesis of [Rh(R)X{C₆H₃(CH₂NMe₂)₂-2,6}](R = Me or Et, X = Cl or I) with Ag(O₂CMe) or Ag(O₃SCF₃). The solid-state structure of [Rh(Me)I{C₆H₃(CH₂NMe₂)₂-2,6}] was determined by an X-ray diffraction study. Crystals are orthorhombic, space group Pbca, with lattice parameters a= 14.899(3), b= 15.744(3), c= 13.191(2)Å, U= 3 094(2)ų, Z= 8, D_c= 1.87 g cm^–3, R= 0.055. The structure has a square-pyramidal five-co-ordinate rhodium centre. One C and two N atoms of the chelating aryl moiety together with the I atom define the basal plane, and the methyl group lies at the apex [Rh–C(aryl) 1.940(8), Rh–C(methyl) 2.029(11)Å]. ¹⁰³Rh N.m.r. studies of the novel five-co-ordinate diorganorhodium(III) compounds have been carried out.