The nickel, copper and zinc complexes of a potentially heptadentate nitrogen donor ligands

Abstract

The synthesis of the potentially heptadentate ligands, tris-(2-aminobenzylidene)amino-ethylamine (L3) and tris-(o-aminobenzyl)aminoethylamine (L4) are reported. Complexes of L3 with nickel copper and zinc have been synthesised and characterised. However, the nickel and zinc compounds are observed to re-arrange during the procedures used to produce samples for X-ray diffraction analysis. In both cases aniline groups are found to migrate to give rise to unique but related coordinated polyamine species. A rational route which allows for the reduction of the imine function in L3 is presented giving rise to a heptadetate ligand (L4) which contains primary, secondary and tertiary amines. Having removed the reactive imine function, the synthesized nickel and copper complexes follow the expected synthetic and structural pattern with the nickel complex being observed to be octahedral and the copper(II) complex five coordinate. The zinc complex is in contrast different. As observed for L3, it is possible to generate simple ZnL3 complexes but these are prone to intramolecular cyclisation where an aniline nitrogen couples with the secondary amine to form a coordinated indizine

Chiral Synthesis of McGeachin-Type Bisaminals

“…13 C{ 1 H} NMR (101 MHz, CDCl 3 , δ): 172. 1, 143.3, 137.3, 129.2, 128.8, 128.3, 127.2, 126.6, 120.8, 116.7, 112.1, 72.6, 64.2, 51.3, 37.5, 36.6 6,11,12epiminodibenzo[b,f ]…”

“…In previous synthetic reports, these bases were classified into pseudo-Troger’s bases or Troger’s base analogues, although they contain different structural motifs (Figure e, X ). McGeachin-type bisaminals have been used as ligand backbones in some transition metal complexes . Additionally, their antibacterial bioactivity was also explored by Son and co-workers …”

Synthetic strategies and diversification of dibenzo[1,5]diazocines

“…18 The electron-rich diazocine structures are also capable of serving as versatile ligands towards metal ions to generate a wide range of fascinating geometric architectures of metal complexes. [19][20][21][22][23] From a structural viewpoint, the symmetric structure of diazocine has eight π-electrons, adopts the boat conformation and is classified as a Hückel anti-aromatic compound. The attractive molecular model comprises diazocines existing as chiral molecules with their absolute configurations well-elucidated by solid-state analysis.…”

“…18 The electron-rich diazocine structures are also capable of serving as versatile ligands towards metal ions to generate a wide range of fascinating geometric architectures of metal complexes. 19–23…”