Distinguishable Zn(ii) and Pb(ii) template effects on forming pendant-armed Schiff-base macrocyclic complexes including a remarkable Pb(ii)–π macrocyclic complex?

Dalton Transactions Pub Date: 2014-08-12 DOI: 10.1039/C4DT01927J

Abstract

36-Membered [2 + 2] half-fold Schiff-base macrocyclic dinuclear Zn(II) complexes (1a and 1b) and 18-membered [1 + 1] Schiff-base macrocyclic mononuclear Pb(II) complexes (2 and 3) are produced from the condensation between 1,3-propanediamine and a pair of extended dialdehydes with different functional pendant arms (H2hpdd and H2pdd) because of the distinguishable cationic template effects. It is very interesting to mention that a unique intramolecular Pb(II)–π macrocyclic complex 2 with an uncommon η3-coordination type is achieved under ambient conditions and it can remain stable both in the solid state and in solution. The subtle variations of pendant-arms in the macrocyclic ligands H2hpdd and H2pdd yield different Pb(II) complexes, where the competition between Pb(II)–π and Pb(II)–NO3? electrostatic interactions as well as the combination of steric and electronic effects of pendant arms are believed to play important roles.

Graphical abstract: Distinguishable Zn(ii) and Pb(ii) template effects on forming pendant-armed Schiff-base macrocyclic complexes including a remarkable Pb(ii)–π macrocyclic complex
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