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

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A family of new Group 3, Group 13 and early transition metal complexes of the previously described monoanionic, pendant arm macrocyclic ligands La, Lb and Lc 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 KLc2a–c by reaction with potassium hydride in tetrahydrofuran (THF). An improved synthesis of HLc1c is also reported. Reaction of KLa–c with Group 13 metal salts MCl3 (M = Al, Ga or In) gives monomeric derivatives [M(κ4-La–c)Cl2] 3–5 in good yields. The crystal structure of [In(κ4-Lb)Cl2] 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(κ4-La–c)Cl2]26a–c. Reaction of [Al(κ4-Lc)Cl2] 3c with AlCl3 gives the unstable, five-coordinate cation [Al(κ4-Lc)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(κ4-L1a–c)Cl2] (M = Sc 8a–c or Y 9b,c) and the early transition metal analogues [M(κ4-Lb,c)Cl2] (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(κ4-L1a–c)] 13a–c as confirmed by the X-ray crystal structures of 13b and 13c. p