New unsymmetrical Schiff base Ni(ii) complexes as scaffolds for dendritic and amino acid superstructures

Mono- and dinucleating Ni(II), Cu(II), Zn(II) and Fe(III) complexes of symmetric and unsymmetric Schiff bases incorporating salicylimine functions – Synthetic and structural studies

“…2) confirmed the previously assigned 'open' single imine structure [11,13] (rather than a 7-membered diaza ring structure of the type obtained previously from the 1:1 condensation of acetylacetone and ethylenediamine) [23]. Reaction of 1 with salicylaldehyde or 5-tert-butyl-salicylaldehyde in situ in the presence of Ni(II), Cu(II), or Zn(II) acetate resulted in metal template syntheses of the corresponding asymmetric Schiff base complexes of type 2: [NiL ]·EtOH the disordered solvent is hydrogen bonded to the coordinated oxygens and weak π-π interactions occur between dimers, resulting in a two-dimensional array that extends throughout the lattice.…”

“…Previous studies [11,13,14] have shown that o-phenylenediamine undergoes 1:1 Schiff base condensation with individual β-diketones; for example, reaction with benzoylacetylacetone yields 3-(2-aminophenylamino)-1-phenylbut-2-en-1-one (1) that incorporates a free amine site [11,13]. As an extension of these prior studies, we now report the metal template syntheses of new Ni(II), Cu(II) and Zn(II) complexes of type 2 (see Fig.…”

“…Individual complexes have been investigated for a number of applications, including as oxygen carriers [5], non-linear optical materials [6], as catalysts (and especially asymmetric catalysts) [2,7], in inorganic biochemical roles [8] and as components of metallosupramolecular systems [2,9]. In contrast to symmetrical Schiff base systems, unsymmetric systems have received significantly less attention, in part reflecting that their syntheses are usually [6,10,11] (but not always) [12] somewhat less facile than for related symmetrical systems.…”

Interaction of Co(ii), Ni(ii) and Cu(ii) with dibenzo-substituted macrocyclic ligands incorporating both symmetrically and unsymmetrically arranged N, O and S donors

“…The Ni-O bond of 2.1214(17) Å slightly exceeds the sum of the covalent radii 28 of octahedral Ni(II) (1.39 Å ) and O (0.66 Å ) however, it is comparable to the mean literature value of 2.15 Å for this bond type. 29 The Ni-N distances 2.0675(17)-2.1214(17) Å fall within the range (2.03-2.16 Å ) observed for such bonds involving neutral sp 3 -hybridised nitrogen atoms in macrocyclic high-spin Ni(II) complexes.…”

A highly novel dinickel complex: A hydrogen-bonded anti-skew carboxylate bridge and a 2D supramolecular structure

“…To explain this, it seems reasonable to assume that there is initial loss of the water of crystallisation and of three coordinated water molecules from axial positions. This could afford four-coordinate square planar Ni(II) species of which related Schiff base compounds are known [25]. Above 110°C, loss of the remaining two water molecules occurs.…”