Tuning the nuclearity of [Mo2O2S2]2+-based assemblies by playing with the degree of flexibility of bis-thiosemicarbazone ligands.

[MoV₂ O₂S₂]²⁺-based thiosemicarbazone complexes appear as very promising molecules for biological applications due to the intrinsic properties of their components. This paper deals with the synthesis and characterization of six coordination complexes obtained by the reaction of [MoV₂ O₂S₂]²⁺ clusters with bisthiosemicarbazone ligands that contain flexible or rigid spacers between the two thiosemicarbazone units. Interestingly, structural characterization by single-crystal X-ray diffraction, MALDI-TOF MS technique and NMR spectroscopy revealed that the nuclearity of the complex is controlled by the nature of the spacer between the thiosemicarbazone units. Binuclear complexes, namely [MoV₂ O₂S₂(L^1-3)], are isolated with flexible spacers while tetranuclear complexes [(MoV² O₂S₂)₂(L^4-6)₂] are formed when the bisthiosemicarbazone ligands are built on rigid spacers. [ABSTRACT FROM AUTHOR]