Experimental and Theoretical Evidence of π-d Interactions in Supramolecular Assemblies Based on TTF-CH=CH-Py Ligands Tethered to Mo6X8i Octahedral Molybdenum Halide Cluster Cores

Synthesis, characterization, and physical properties of [Mo6X8i(TTF-CH=CH-py)(6)(a)](4+) supramolecular assemblies [TTF = tetrathiafulvalene; Py = pyridine; X = Cl (1), Br (2), 1 (3)] resulting from the reaction between [Mo6X8i-(OSO2CF3)(6)](2-) cluster precursor and TTF-CH=CH-Py ligands were investigated. They are based on the association of the strongly delocalized metallic electron [Mo6X8i](4+) cluster cores with six redox-active n-conjugated TTF-CH=CH-Py terminal ligands attached to the Mo clusters through the pyridinyl group. Synergetic pi-d interactions between the organic ligands and the cluster core were experimentally evidenced by electrochemistry and absorption measurements, and corroborated by DFT calculations. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)