TitleMolecular lanthanide fluorides
NameRomanelli, Michael Dennis (author), Garfunkel, Eric (chair), Brennan, John (internal member), Potenza, Joseph (internal member), Goldman, Alan (internal member), Riman, Richard (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectChemistry and Chemical Biology,
DescriptionNovel molecular lanthanide (Ln) species have been prepared that showcase not only their exceptional optical properties but also deviations from the "typical" reaction/product schemes realized over the past few decades. Ln chalcogenolates [(L)xLn(SC6F5)3 and (L)xLn(SeC6F5)3; (Ln = Pr, Nd, Sm, Er, or Yb; L = pyr, DME, or THF); x = 3 or 4] have been prepared and their optical and structural properties are discussed. The photoluminescence quantum efficiency (QE), radiative decay, and effective bandwidth for the 4F11/2 --> 4I9/2 transition of Nd(SC6F5)3(DME)3 were found to be 9%, 1.39ms, and 59nm, respectively. At the time, this was one of the highest reported quantum efficiencies for a molecular Nd species.
Ligand, metal radii, and neutral donor molecule have been found to influence the physical and optical properties of these species. By changing any one of these variables, vastly different products can arise; for example, 7-coordinate [Nd(SC6F5)3(THF)3]2 with bridging thiolates , 7-coordinate Nd(SeC6F5)3(THF)3 , and 8-coordinate Nd(SC6F5)3(DME)2, have all been successfully isolated. Using the same ligand and neutral donor with Er gives 6-coordinate Er(SeC6F5)3(THF)3, a near perfect octahedral geometry with a significant structural trans influence. DFT calculations indicate that the trans influence in these bond lengths result from covalent Ln-E interactions.
Cluster compounds DME3Yb4F2O(OCH2CH2OCH3)2(SeSe)(SC6F5)4•DME and
(pyr)24Ln28F68(SePh)16 (Ln = Ce, Nd, Pr) have been prepared by C-F bond activation and direct fluoride source (NH4F), respectively. At 41%, the 4F11/2 --> 4I9/2 transition of (pyr)24Nd28F68(SePh)16 has the highest QE to date for any molecular Nd species.
(pyr)xM(SeC6F5)2 (M = Zn, Cd, Hg and x = 0 or 2) were synthesized by reductive cleavage of F5C6SeSeC6F5 by the respective metals. Both the Zn and Cd species have tetrahedral coordination environments. The Hg analog has a near linear, modulated structure, with no coordinated pyridine ligands. These molecular II-VI semiconductor precursors melt between 115 and 175°C and when heated to 650°C under reduced pressures, give crystalline MSe (M = Zn, Cd, Hg) products.
NoteIncludes bibliographical references
Noteby Michael Dennis Romanelli
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.