The reduction potentials (reported vs. Fc + /Fc) for a series of Cp′ 3 Ln complexes (Cp′ = C 5 H 4 SiMe 3 , Ln = lanthanide) were determined via electrochemistry in THF with [ n Bu 4 N][BPh 4 ] as the supporting electrolyte. The Ln( iii )/Ln( ii ) reduction potentials for Ln = Eu, Yb, Sm, and Tm (−1.07 to −2.83 V) follow the expected trend for stability of 4f 7 , 4f 14 , 4f 6 , and 4f 13 Ln( ii ) ions, respectively. The reduction potentials for Ln = Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu, that form 4f n 5d 1 Ln( ii ) ions ( n = 2–14), fall in a narrow range of −2.95 V to −3.14 V. Only cathodic events were observed for La and Ce at −3.36 V and −3.43 V, respectively. The reduction potentials of the Ln( ii ) compounds [K(2.2.2cryptand)][Cp′ 3 Ln] (Ln = Pr, Sm, Eu) match those of the Cp′ 3 Ln complexes. The reduction potentials of nine (C 5 Me 4 H) 3 Ln complexes were also studied and found to be 0.05–0.24 V more negative than those of the Cp′more »
Trends in trigonal prismatic Ln[1]ferrocenophane complexes and discovery of a Ho ^{3+} singlemolecule magnet
Lanthanide metallocenophanes are an intriguing class of organometallic complexes that feature rare sixcoordinate trigonal prismatic coordination environments of 4f elements with close intramolecular proximity to transition metal ions. Herein, we present a systematic study of the structural and magnetic properties of the ferrocenophanes, [LnFc 3 (THF) 2 Li 2 ] − , of the late trivalent lanthanide ions (Ln = Gd ( 1 ), Ho ( 2 ), Er ( 3 ), Tm ( 4 ), Yb ( 5 ), Lu ( 6 )). One major structural trend within this class of complexes is the increasing diferrocenyl (Fc 2− ) average twist angle with decreasing ionic radius ( r ion ) of the central Ln ion, resulting in the largest average Fc 2− twist angles for the Lu 3+ compound 6 . Such high sensitivity of the twist angle to changes in r ion is unique to the here presented ferrocenophane complexes and likely due to the large trigonal plane separation enforced by the ligand (>3.2 Å). This geometry also allows the nonKramers ion Ho 3+ to exhibit slow magnetic relaxation in the absence of applied dc fields, rendering compound 2 a rare example of a Hobased singlemolecule magnet (SMM) more »
 Award ID(s):
 1753014
 Publication Date:
 NSFPAR ID:
 10157308
 Journal Name:
 Chemical Science
 Volume:
 11
 Issue:
 15
 Page Range or eLocationID:
 3936 to 3951
 ISSN:
 20416520
 Sponsoring Org:
 National Science Foundation
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