<b>Fundamental Inorganic Chemistry for Renewable Energy Resources: Highlights in Tellurium, Zirconium, Hafnium, and Neptunium Coordination Chemistry</b>
Creators: name: Uible, Madeleine Claire
Publisher: name: Purdue University Graduate School
Year: 2024
Subjects: classificationCode: 340203
subject: F-block chemistry
classificationCode: 340205
subject: Main group metal chemistry
classificationCode: 340202
subject: Crystallography
classificationCode: 340209
subject: Organometallic chemistry
classificationCode: 340211
subject: Transition metal chemistry

description: The separation of tellurium from cadmium telluride is examined using a unique combination of mild, anhydrous chlorination and complexation of the subsequent tellurium tetrachloride with 3,5-di-<i>tert</i>-butylcatechol. The resulting tellurium complex, Te(dtbc)<sub>2</sub>, is isolated in moderate yield and features a 10<sup>3</sup> to 10<sup>4</sup> reduction in cadmium content, as provided by XRF and ICP-MS analysis. Similar results were obtained from zinc telluride. A significant separation between Te, Se, and S was observed after treating a complex mixture of metal chalcogenides with this protocol. These three tunable steps can be applied for future applications of CdTe photovoltaic waste.We report the synthesis and characterization of the first series of tellurium and selenium complexes featuring an η<sup>5</sup>-cyclopentadienyl ligand. Reaction of Ph<sub>3</sub>TeX (X = Cl, S<sub>2</sub>CNEt<sub>2</sub>) with MCp<sup>R</sup> (M = Li, K; R = H, Me<sub>4</sub>, Me<sub>5</sub>) results in high yields of [Cp][TePh<sub>3</sub>] (<b>1</b>), [Cp<sup>Me4</sup>][TePh<sub>3</sub>] (<b>2</b>), and [Cp*][TePh<sub>3</sub>] (<b>3</b>), respectively. Similarly, reaction of Ph<sub>3</sub>SeCl with LiCp and KCp* furnishes [Cp][SePh<sub>3</sub>] (<b>4</b>) and [Cp*][SePh<sub>3</sub>] (<b>5</b>). Each was characterized by X-ray crystallography, revealing similar η<sup>5</sup>-coordination with little distortion from an idealized half-sandwich geometry, presumably from the remaining lone pair on tellurium and selenium. The Te–centroid distances are relatively long (<b>1</b>: 2.770(3), <b>2</b>: 2.746(1), and <b>3</b>: 2.733(1) Å), suggesting a mostly ionic interaction. Se–centroid distances (<b>4</b>: 2.748(3), <b>5</b>: 2.707(2), 2.730(2) Å) were found to be surprisingly similar despite its smaller atomic radius. Compounds <b>2</b>, <b>3</b>, and <b>5</b> display rapid decomposition at room temperature, extruding a phenylated cyclopentadiene and the and the respective diphenylchalcogenide. The nature of bonding within these complexes was investigated through DFT methods and found to be primarily ionic in nature.Synthesis of homoleptic zirconium and hafnium dithiocarbamate via carbon disulfide insertion into zirconium and hafnium amides were investigated for their utility as soluble molecular precursors for chalcogenide perovskites and binary metal sulfides. Treating M(NEtR)<sub>4</sub> (M= Zr, Hf and R= Me, Et) with CS<sub>2</sub> resulted in quantitative yields of homoleptic Group IV dithiocarbamates. Zr(k<sup>2</sup>-S<sub>2</sub>CNMeEt) (<b>1</b>), Zr(k<sup>2</sup>-S<sub>2</sub>CNEt<sub>2</sub>)<sub>4</sub> (<b>2</b>), and Hf(k<sup>2</sup>-S<sub>2</sub>CNEt<sub>2</sub>)<sub>4 </sub>(<b>4</b>), a rare example of a crystal of a homoleptic hafnium CS<sub>2</sub> inserted amide species, were characterized. A computational analysis confirmed assignments for IR spectroscopy.<b> </b>To exemplify the utility of the Group IV dithiocarbamates, a solution-phase nanoparticle synthesis was performed to obtain ZrS<sub>3</sub> via the thermal decomposition of Zr(S<sub>2</sub>CNMeEt)<sub>4</sub>Chalcogenide perovskites have garnered interest for applications in semiconductor devices due to their excellent predicted optoelectronic properties and stability. However, high synthesis temperatures have historically made these materials incompatible with the creation of photovoltaic devices. Here, we demonstrate the solution processed synthesis of luminescent BaZrS<sub>3</sub> and BaHfS<sub>3</sub> chalcogenide perovskite films using single-phase molecular precursors at sulfurization temperatures of 575 °C and sulfurization times as short as one hour. These molecular precursor inks were synthesized using known carbon disulfide insertion chemistry to create Group 4 metal dithiocarbamates, and this chemistry was extended to create species, such as barium dithiocarboxylates, that have never been reported before. These findings, with added future research, have the potential to yield fully solution processed thin films of chalcogenide perovskites for various optoelectronic applications.Np(IV) Lewis base adducts were prepared by ligand substitution of NpCl<sub>4</sub>(DME)<sub>2</sub>. Using acetonitrile and pyridine, NpCl<sub>4</sub>(MeCN)<sub>4</sub> (<b>1</b>) and NpCl<sub>4</sub>(pyr)<sub>4</sub> (<b>2</b>), were isolated, respectively. All species were fully characterized using spectroscopic and structural analyses.