Rhenium(V) Complexes Containing Mono- and Tridentate Imido Ligands: Crystal Structures, Spectroscopic Results and DFT Optimization

Rhenium(V) complexes containing the [ReX(PPh3)2]4+ (X = Br, I) moiety were studied. The reaction of N-(2-aminophenyl)salicylideneimine (H3pna) with trans-[ReOBr3(PPh3)2] produced the complex salt [Re(pna)Br(PPh3)2]0.5Br.0.5(ReO4) (1), in which the tridentate ligand pna is coordinated via a doubly  deprotonated nitrogen (as an imide), an imino nitrogen and a deprotonated phenolate oxygen atom. The reaction of trans-[ReO(OEt)I2(PPh3)2] with two equivalents of 2-aminophenol (H3ap) in ethanol led to the isolation of the ‘2+1’ complex salt [Re(Hap)(H2ap)I(PPh3)2]I (2) in good yield. TheHapligand is coordinated  monodentately via the doubly deprotonated imido nitrogen, and H2ap is chelated bidentately through the neutral amino nitrogen and a deprotonated phenolate oxygen atom. The crystal structures of 1 and 2 were determined by X-ray single crystal diffraction. Spectroscopic results and DFT calculations are also reported.KEYWORDS: Rhenium(V), tridentate imido, ‘2 + 1’ coordination, X-ray crystal structures, DFT

Preparation and electrochemical properties of nanoporous transparent antimony-doped tin oxide (ATO) coatings

Nanoporous antimony-doped tin oxide (ATO) coatings with high surface area, optical transparency and electron transfer properties have been prepared using an interpenetrating inorganic–organic hybrid sol–gel approach. UV-Vis and X-ray photoelectron spectroscopic studies were carried out on the prepared materials in addition to the characterization of their microstructures with scanning electron microscopy, transmission electron microscopy, and nitrogen sorption experiments. Cyclic voltammetry (CV) and impedance spectroscopy were employed to characterize the electrochemical and electron transfer properties of the coatings in both acidic and neutral media with an Fe3+/Fe2+ redox couple. The material had a specific surface area of over 90 m2 g−1 with a bimodal pore distribution with two distinctive peaks at ca. 8 and 40 nm. The electrochemical capacitance of the material was about 100 times as high as the value obtained for a commercially available nonporous fluorine-doped tin oxide (FTO) electrode. The estimated electron transfer rate of the former was three times larger than that of the FTO. The optical transparency, high surface area and high electron transfer rate of the nanoporous ATO coatings make the material well suited for diverse photoelectrochemical applications.by Sudhanshu Sharma et al.