While reducing the use of organic solvents is obvious from a green chemistry perspective, the availability and disposal costs of these solvents are often overlooked. These costs, especially at isolated, underserved institutions make even the most mundane and basic chemistry experiments inaccessible. For these reasons, mechanochemistry has become an increasingly sought-after synthetic approach for reactions ranging from covalent to coordination chemistry. Previously, we investigated a mechanochemical approach for displacing hydrate ligands on lanthanide beta-diketonate complexes of the type Ln(hfac)3(H2O)3 (Ln =La-Sm) with variable success. In order to improve the yields of these reactions and increase the scope of our mechanochemical methods, we investigated preparing these lanthanide coordination complexes directly from their chloride salts-mechanochemically. In doing so, we also confronted the surprisingly difficult to characterize lanthanide beta-diketonate hydrate materials, which are common precursors for compounds with unique optical and/or magnetic properties. In pursuing different synthetic techniques, we offer experimental insights as to why these lanthanide beta-diketonate hydrates can be troublesome as starting materials. We used DSC-TGA-MS to probe the mass loss and decomposition of the Ln(hfac)3(H2O)x complexes as well as XRD and IR to careful study these complexes and look at possible decomposition pathways. During the course of these studies, we also discovered reactivity differences of the Ln(hfac)3(H2O)x materials with bidentate donor ligands depending on how the starting material hydrates were synthesized.

Room for improvement: Lessons learned from the mechanochemical synthesis of lanthanide coordination complexes

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.