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Matson, Ellen M.

Publications and source records attributed to Matson, Ellen M..

29 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Synthesis and Characterization of Pyridine Dipyrrolide Uranyl Complexes

The first actinide complexes of the pyridine dipyrrolide (PDP) ligand class, ( Mes PDP Ph )UO 2 (THF) and ( Cl2Ph PDP Ph )UO 2 (THF), are reported as the U VI uranyl adducts of the bulky aryl substituted pincers ( Mes PDP Ph ) 2– and ( Cl2Ph PDP Ph ) 2– (derived from 2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine (H 2 Mes PDP Ph , Mes = 2,4,6-trimethylphenyl), and 2,6-bis(5-(2,6-dichlorophenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine (H 2 Cl2Ph PDP Ph , Cl 2 Ph = 2,6-dichlorophenyl), respectively). Following the in situ deprotonation of the proligand with lithium hexamethyldisilazide to generate the corresponding dilithium salts (e.g., Li 2 Ar PDP Ph , Ar = Mes of Cl 2 Ph), salt metathesis with [UO 2 Cl 2 (THF) 2 ] 2 afforded both compounds in moderate yields. The characterization of each species has been undertaken by a combination of solid- and solution-state methods, including combustion analysis, infrared, electronic absorption, and NMR spectroscopies. In both complexes, single-crystal X-ray diffraction has revealed a distorted octahedral geometry in the solid state, enforced by the bite angle of the rigid meridional ( Ar PDP Ph ) 2– pincer ligand. The electrochemical analysis of both compounds by cyclic voltammetry in tetrahydrofuran (THF) reveals rich redox profiles, including events assigned as U VI /U V redox couples. Here, a time-dependent density functional theory study has been performed on ( Mes PDP Ph )UO 2 (THF) and provides insight into the nature of the transitions that comprise its electronic absorption spectrum.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Development of sterically hindered siloxide-functionalized polyoxotungstates for the complexation of 5d-metals

In this study, we extend the family of organosilyl-functionalized trivacant Keggin polyoxotungstates, [PW 9 O 34 (RSiOH) 3 ] 3− (R = n Pr, i Pr, t Bu), through the introduction of bulky aryl and aliphatic silanol substituents, namely phenyl, cyclohexyl and biphenyl. This work was performed in order to study the impact of these large functional groups on the accessibility of the well-defined tridentate coordination site. Coordination of hafnium to these type II hybrid polyoxotungstates was conducted in order to study the ability of the bulkier ligand pockets to support larger cations in comparison to those previously reported (e.g. Ti 4+ , V 3+ , V 5+ , Ge 4+ ). Increased steric hindrance around the coordination site from the biphenyl groups resulted in much longer reaction times for the complexation reaction compared to the other functional groups used, but the impact of our design toward stabilizing reactive species proved limited, as all complexes easily undergo hydrolysis of the Hf-O t Bu bond in the presence of water. As a result, electrochemical investigations of the ligands and hafnium complexes reveal that the redox events centered on the polyoxotungstate core can be tuned by varying the substituents on the silyl fragment, and exhibit a cathodic shift after coordination of the redox inactive tetravalent cation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Light-driven hydrogen production with CdSe quantum dots and a cobalt glutathione catalyst

A photocatalytic hydrogen (H 2 ) production system is reported using glutathione (GSH)-capped CdSe QDs with a cobalt precatalyst, yielding 130 000 mol H 2 per mol cobalt over 48 hours. Analysis of the reaction mixtures after catalysis indicates that the active catalyst is a labile complex of cobalt and GSH formed in situ.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Characterizing Polyoxovanadate‐Alkoxide Clusters Using Vanadium K‐Edge X‐Ray Absorption Spectroscopy

Abstract A number of technologies would benefit from developing inorganic compounds and materials with specific electronic and magnetic exchange properties. Unfortunately, designing compounds with these properties is difficult because metal⋅⋅⋅metal coupling schemes are hard to predict and control. Fully characterizing communication between metals in existing compounds that exhibit interesting properties could provide valuable insight and advance those predictive capabilities. One such class of molecules are the series of Lindqvist iron‐functionalized and hexavanadium polyoxovanadate‐alkoxide clusters, which we characterized here using V K‐edge X‐ray absorption spectroscopy. Substantial changes in the pre‐edge peak intensities were observed that tracked with the V 3 d ‐electron count. The data also suggested substantial delocalization between the vanadium cations. Meanwhile, the Fe III cations were electronically isolated from the polyoxovanadate core.

Meyer, Rachel L.↗
DOE OSTI2020

Polyoxometalate-based complexes as ligands for the study of actinide chemistry

The complexation of actinide cations by polyoxometalates (POMs) has been extensively studied over the past 50 years. In this perspective article, we present the rich structural diversity of actinide-POM complexes and their contribution to the extension of our knowledges of actinide chemistry, especially regarding aspect of their redox chemistry, as well as application for the capture and separation of these cations in the context of nuclear fuel remediation. Furthermore, these heterometallic assemblies have also proven highly valuable as model for heterogeneous systems based on actinides supported by metal oxide surfaces. In particular, activation of the An–O bond of actinyl fragments upon complexation with lacunary POMs has been reported, creating opportunities for future developments regarding the reactivity of these heterometallic assemblies.

Auvray, Thomas↗