Selective syntheses of homo- and hetero-dimetal complexes with the tetramethyltetraazaannulene ligand of the type [(ML,M ' L ')(TMTAA)], where M and M ' are Rh(I) or Ir(I) and L and L ' are COD or (CO)(2)

摘要

The tetraazamacrocycle, tmtaaH(2), reacts with [M-2(COD)(2)(mu-OH)(2)], M = Rh or Ir, to give [M(tmtaaH)-(COD)], which give the dicarbonyl derivatives, [ M( tmtaaH)(CO)(2)], on exposure to CO. The COD and dicarbonyl derivatives, M) Rh, are methylated with MeOTf at the beta-carbon site of the imidinate ring, giving [Rh(tmtaaHMe)(L-2)](+), where L-2 = COD or (CO)(2). The crystal structure of [Rh(tmtaaHMe)(CO)(2)]-[OTf] shows that the site of methylation is the imidinate ring that contains the Rh( CO) 2 fragment. Protonation by HOTf also occurs at the beta-carbon site of the imidinate ring, assumed to be the ring that contains the Rh(L-2) fragment. The dicarbonyls are deprotonated by LiN(SiMe3)(2) in thf, giving [M(CO)(2)-(tmtaa)Li(thf)]. A crystal structure of M = Rh shows an intramolecular Li-Rh distance of 2.635(10) angstrom and an intermolecular Rh center dot center dot center dot Rh contact distance between two molecular units of 3.198(1) angstrom that align along their molecular z-axis. Addition of MeI to [M(CO)(2)(tmtaa)Li(thf)]yields [M(tmtaaMe)(CO)(2)], where the methyl group is attached to the imidinate ring that contains the Li(thf) fragment, as shown by X-ray crystallography. The [M(tmtaaH)(CO)(2)] reacts with half an equivalent of [M-2(COD)(2)(mu-OH)(2)] to give the mixed dimetal complexes [M(CO)(2)(tmtaa)M'(COD)], where M, M' is either Rh, Rh or Rh, Ir, which react with CO to give [MM'(tmtaa)(CO)(4)].