New main-group and early transition-metal complexes of mono-pendant arm triazacyclononane ligands

Article abstract of DOI:10.1039/b008267h

A family of new Group 3, Group 13 and early transition metal complexes of the previously described monoanionic, pendant arm macrocyclic ligands L^a, L^b and L^c are described where HL^a = (3,5-dimethyl-2-hydroxybenzyl)-4,7-diisopropyl-1,4,7-triazacyclononane 1a, HL^b = (3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-diisopropyl-1,4,7-triazacyclonon ane 1b, and HL^c = (3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-dimethyl-1,4,7-triazacyclononane 1c. The ligand precusors 1a-c are quantitatively converted to the corresponding new potassium salts KL^a, KL^b and KL^c 2a-c by reaction with potassium hydride in tetrahydrofuran (THF). An improved synthesis of HL^c 1c is also reported. Reaction of KL^a-c with Group 13 metal salts MCl₃ (M = Al, Ga or In) gives monomeric derivatives [M(κ⁴-L^a-c)Cl₂] 3-5 in good yields. The crystal structure of [In(κ⁴-L^b)Cl₂] 5b has been determined and confirms the six-coordinate, cis-dichloride structures proposed for these complexes. Reaction of KL^a-c with TlCl₃ gives the asymmetric, binuclear analogues [Tl(κ⁴-L^a-c)Cl₂]₂ 6a-c. Reaction of [Al(κ⁴-L^c)Cl₂] 3c with AlCl₃ gives the unstable, five-coordinate cation [Al(κ⁴-L^c)Cl]⁺ as its AlCl₄^- salt 8c. Reaction of KL^a-c with MCl₃, (M = Sc or Y) or [MCl₃(THF)₃] (M = Ti, V, Cr) in THF gives generally good yields of the Group 3 cis-dichloride derivatives [M(κ⁴-L^1a-c)Cl₂] (M = Sc 8a-c or Y 9b,c) and the early transition metal analogues [M(κ⁴-L^b,c)Cl₂] (M = Ti 10b,c, V 11b,c or Cr 12b,c). Reaction of HL^1a-c with TlOEt yields the monomeric, four-coordinate thallium(I) derivatives [Tl(κ⁴-L^1a-c)] 13a-c as confirmed by the X-ray crystal structures of 13b and 13c. The Royal Society of Chemistry 2001.