Control of molecular architecture by use of the appropriate ligand isomer: a mononuclear "corner-type" versus a tetranuclear [2 x 2] grid-type cobalt(III) complex.

Employing two isomeric pyrazine-based ligands a [2 x 2] grid-type tetranuclear cobalt(III) complex, incorporating doubly deprotonated (La)2- ligands, and a "corner-type" mononuclear cobalt(III) complex, incorporating neutral H2Lp ligands in a zwitterionic form, have been synthesised and structurally characterised.