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

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 HLa = (3,5-dimethyl-2-hydroxybenzyl)-4,7-diisopropyl-1,4,7-triazacyclononane 1a, HLb = (3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-diisopropyl-1,4,7-triazacyclononane 1b, and HLc = (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 KLa, KLb and KLc 2a-c by reaction with potassium hydride in tetrahydrofuran (THF). An improved synthesis of HLc 1c is also reported. Reaction of KLa-c with Group 13 metal salts MCl3 (M = Al, Ga or In) gives monomeric derivatives [M(kappa (4)-La-c)Cl-2] 3-5 in good yields. The crystal structure of [In(kappa (4)-L-b)Cl-2] 5b has been determined and confirms the six-coordinate, cis-dichloride structures proposed for these complexes. Reaction of KLa-c with TlCl3 gives the asymmetric, binuclear analogues [Tl(kappa (4)-La-c)Cl-2](2) 6a-c. Reaction of [Al(kappa (4)-L-c)Cl-2] 3c with AlCl3 gives the unstable, five-coordinate cation [Al(kappa (4)-L-c)Cl](+) as its AlCl4- salt 8c. Reaction of KLa-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(kappa (4)-L1a-c)Cl-2] (M = Sc 8a-c or Y 9b,c) and the early transition metal analogues [M(kappa (4)-L-b,L-c)Cl-2] (M = Ti 10b,c, V 11b,c or Cr 12b,c). Reaction of HL1a-c with TlOEt yields the monomeric, four-coordinate thallium(I) derivatives [Tl(kappa (4)-L1a-c)] 13a-c as confirmed by the X-ray crystal structures of 13b and 13c.