Toward new paradigms in mixed-valency: ytterbocene–terpyridine charge-transfer complexes

Abstract

(C5Me5)2Yb x OEt2 reacts with terpyridine and tetrapyridinylpyrazine to afford new mixed-valent systems.

Comparative Study of f-Element Electronic Structure across a Series of Multimetallic Actinide and Lanthanoid-Actinide Complexes Possessing Redox-Active Bridging Ligands

“…36,37 In previous reports, complexes 5a-b as well as (C 5 Me 5 ) 2 Yb(tpy) (11) and (C 5 Me 5 ) 2 U(tpy) (12) were analyzed for comparison with the multimetallic complexes 6a-b and 7a-b. 25,27,38 Complexes 5a-b showed noteworthy voltammetric responses themselves. As presented in Figure 5, complex 5a displays a set of two quasi-reversible waves at -2.42…”

Lanthanide(III)/Actinide(III) Differentiation in the Cerium and Uranium Complexes [M(C5Me5)2(L)]0,+ (L=2,2′‐Bipyridine, 2,2′:6′,2′′‐Terpyridine): Structural, Magnetic, and Reactivity Studies

“…Crystals of the cerium analogue 4 a were not obtained, and the geometrical parameters of 4 b can only be compared with those of the previously reported ytterbium congener. [12] The U À N distances in 4 b are practically equal to the YbÀN distances, although the ionic radius of U III is 0.15 larger than that of Yb III . [20] Although the YbÀN distances would be abnormally large due to steric effects, [12] the UÀN distances appear significantly shorter than those predicted from a purely ionic bonding model.…”

“…[12] The U À N distances in 4 b are practically equal to the YbÀN distances, although the ionic radius of U III is 0.15 larger than that of Yb III . [20] Although the YbÀN distances would be abnormally large due to steric effects, [12] the UÀN distances appear significantly shorter than those predicted from a purely ionic bonding model. The greatest deviations of the U À N distances in 1 b, 3 b, and 4 b from an electrostatic bonding model, by comparison with those noted in the other analogous lanthanide(iii) and uranium(iii) complexes with polydentate nitrogen ligands, [3][4][5][6] can be explained by the greater electron richness and p-donating capacity of the U(Cp*) 2 moiety, and electron transfer from the metal to a single instead of several p-acceptor ligands.…”

“…[2] Lanthanide complexes with polydentate nitrogen ligands have already been reported, [1c, 3-8] in particular the 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen) and 2,2':6',2''-terpyridine (terpy) adducts of bis(pentamethylcyclopentadienyl)lanthanides [Ln(Cp*) 2 (bipy)] and [Ln(Cp*) 2 (phen)] (Cp* = C 5 Me 5 ; Ln = Sm or Yb) [9][10][11] and [Yb(Cp*) 2 (terpy)]. [12] These compounds have the formal appearance of divalent lanthanide compounds but are in fact Ln III complexes with a ligand radical anion. In addition to their structural and physicochemical properties, such species are attractive for their reactivity, since they are considered to be synthetic equivalents of low-valent species.…”

Coordination of 1,4-Diazabutadiene Ligands to Decamethylytterbocene: Additional Examples of Spin Coupling in Ytterbocene Complexes

“…[1][2][3] The terpyridine and substituted terpyridine complexes of decamethylytterbocene behave similarly. 6, 7 The implication of strong antiferromagnetic coupling in these ytterbocene-bipy complexes provides new ways of thinking about the specific role that electrons in f-orbitals play in bonding in these particular complexes, where an unpaired electron resides in a ligand molecular orbital, which is related to the concept of covalence in felement compounds in general. 8 This paper continues our phenomenological studies of exchange coupling in decamethylytterbocene complexes by preparing the 1,4-diazabutadiene complexes (C 5 Me 5 ) 2 Yb(RN=C(R')C(R')=NR), where R is an alkyl (Me 3 C, Me 2 HC and adamantyl) or aryl (p-tolyl, p-anisyl and mesityl) group and R' is either H or Me, abbreviated Cp* 2 Yb(dad(R')-R).…”