Lanthanide induced variability in localised Co geometries of four triangular LCo Ln complexes.

Four tetranuclear heterobimetallic triangle complexes [LCoDy(NO)(HO)(MeOH)](NO) (C1), [LCoGd(NO)(MeOH)] (C2), [LCoLa(NO)(HO)](NO)(HO) (C3), and [LCoTbCl(NO)(HO)(MeOH)] (C4), where HL = 1,4-bisformylnaphthalene-2,3-diol, have been synthesised and structurally characterised. Each complex crystallises with a complete molecule in the asymmetric unit (' = 1) and displays near perfect octahedrality in two out of three Co centres. The third Co ion assumes a different coordination geometry in each complex: six-coordinate octahedral in C1, six-coordinate with a distortion towards trigonal prismatic in C2, five-coordinate trigonal bipyramidal in C3, and five-coordinate square pyramidal in C4; which has been attributed to increasing lanthanide cation size, coupled with a non-macrocyclic coordination environment.