More surprising differences between two closely similar compartmental ligand families and another dinuclear synthon to stabilize dinuclear–mononuclear cocrystals?

CrystEngComm Pub Date: 2013-06-20 DOI: 10.1039/C3CE40569A

Abstract

This paper presents syntheses, characterization, crystal structures and magnetic properties of two diphenoxo-bridged heterodinuclear CuIIMnII/CuIIFeII compounds [CuIIL1MnII(H2O)3](ClO4)2 (1) and [CuIIL1FeII(H2O)3](ClO4)2 (2) and two tetranuclear CuII3MnII/CuII3FeII compounds [{CuIIL2MnII(H2O)(MeOH)2}(CuIIL2)2](ClO4)2·MeOH (3) and [{CuIIL2FeII(H2O)(MeOH)2}(CuIIL2)2](ClO4)2·MeOH (4) derived from two 3-methoxysalicylaldehyde-diamine Schiff base compartmental ligands H2L1 and H2L2, in which the diamine counterpart comes from 1,3-diaminopropane and o-phenylenediamine, respectively. The two compounds 1 and 2 crystallize in the same space group (monoclinic P21/n) with practically identical unit cell parameters and are isomorphous. Similarly, the two compounds 3 and 4 crystallize in the same space group (monoclinic P21/c) with practically identical unit cell parameters and are isomorphous. The tetranuclear [{CuIIL2MII(H2O)(MeOH)2}(CuIIL2)2]2+ dication in 3 (M = Mn) and 4 (M = Fe) is a self-assembly of one diphenoxo-bridged dinuclear [CuIIL2MII(H2O)(MeOH)2]2+ dication and two mononuclear [CuIIL2] units. One mononuclear unit is self-assembled with the dinuclear unit by four bifurcated water?phenoxo/methoxy (O–H?O) hydrogen bonds and three π?π stacking interactions, while the second mononuclear unit is interlinked with the dinuclear unit by one methanol?phenoxo (O–H?O) hydrogen bond only. Clearly, compounds 3 and 4 are [2 × 1 + 1 × 2] cocrystals of one dinuclear and two mononuclear units. Variable-temperature magnetic susceptibility measurements of all the four compounds have been carried out, revealing moderate antiferromagnetic interaction between the copper(II) and manganese(II)/iron(II) in the dinuclear cores with J values (H = ?2JS1S2) ?29.1, ?36.9, ?15.9 and ?20.2 cm?1, respectively. The magnetic properties are in line with those of previous related examples. Unique features in the structures of 1–4 have been discussed.

Graphical abstract: More surprising differences between two closely similar compartmental ligand families and another dinuclear synthon to stabilize dinuclear–mononuclear cocrystals
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