Deeply Reduced Chiral Mo IV 6 -Polyoxometalates with Highly Enhanced Electronic Conductivity

A series of deeply reduced Mo -polyoxometalates (POMs), [Mo (bpy) Mo O S ]·10H O ( ) (bpy = 2,2'-bipyridine), [Mo (bpy) (L-TrA) Mo (bpy) O S ] ·36.5H O ( ), and [Mo (bpy) (D-TrA) Mo (bpy) O S ] ( ) (TrA = tartaric acid), were obtained from one-pot hydrothermal syntheses. They feature the bioxo-bridged [Mo O S] incomplete cuboidal cores stabilized by strong triangular metal-metal bonds and datively chelated bpy π-ligands. The two apical Mo O in 12e-Mo ( ) and two [Mo O STrAbpy] in 16e-Mo ( , ) complete the octahedral coordination geometry of the deeply reduced Mo , not counting the Mo -Mo d -d bonds. The aromatic planar bpy π ligands form a two-dimensional face-to-face π stacking supramolecular structure, which are further strengthened by point-to-face C-H···π interactions in the π stacked layers. 16e-Mo ( ) has stronger intramolecular face-to-face π stacking interactions, which are interconnected by intermolecular C-H···π into a three-dimensional framework structure. These structural features account for their highly enhanced electronic conductivities ( , 6.19 × 10 S cm ; , 2.18 × 10 S cm ), providing a new way of thinking to improve electronic conductivity of POMs. - have been described by first-principles density function theory (DFT) calculations and also characterized by elemental analyses, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), solid UV-visible spectra, and circular dichroic (CD) spectra.