Ytterbocenes as One‐ and Two‐Electron Reductants in their Reactions with Diazadienes: Yb^III Mixed‐Ligand Bent‐Sandwich Complexes Containing a Dianion of Diazabutadiene

Abstract

Ytterbocene [Yb(C(5)MeH(4))(2)(thf)(2)] reacts with diazabutadiene 2,6-iPr(2)C(6)H(3)-N=CH-CH=N-C(6)H(3)iPr(2)-2,6 (DAD) as a one-electron reductant to afford a bis(cyclopentadienyl) Yb(III) derivative containing a DAD radical anion [Yb(C(5)MeH(4))(2)(dad(-.))]. However, ytterbocenes [YbCp*(2)(thf)(2)] (Cp*=C(5)Me(5), C(5)Me(4)H) coordinated by sterically demanding cyclopentadienyl ligands act as two-electron reductants in their reactions with DAD. These reactions occur by abstraction of one Cp* ring and result in the formation of novel Yb(III) mixed-ligand bent-sandwich complexes, [YbCp*(dad)(thf)], in which the dianion of DAD has an uncommon terminal eta(4)-coordination to the ytterbium atom. The variable-temperature magnetic measurements of complex [Yb(C(5)Me(5))(dad)(thf)] suggest the existence of redox tautomerism for this compound.

Orientation-Induced Redox Isomerism in Planar Supramolecular Systems

“…3,4 Only a few works are devoted to the study of IET in aggregated molecules (including liquid crystals). 5,6,13 In systems characterized by the coexistence of two redox isomers of the same compound, we can suppose that not only driving forces listed above (light, temperature, microenviron ment), but any physical effect that even slightly affects the internal energy of the system can shift the dynamic equilibrium toward the predominance of one of the isomers. The present work is devoted to the study of such physical effects that accompanies 3D−2D transition of discotic molecules as well as phase transitions in 2D systems.…”

Genuine Redox Isomerism in a Rare‐Earth‐Metal Complex

“…In 2007, the occurrence of redox isomerism was claimed for a complex of an f element, [(dpp-dad)Yb(C 5 Me 5 )(thf)] (dpp-dad = 1,4-bis(2,6-diisopropylphenyl)diaza-1,3-butadiene). [4] Based on the solid-state magnetic susceptibility it was proposed that at 2 K the complex consists of Yb II and a dpp-dad radical anion, while at 300 K it is present as Yb III with a dpp-dad dianion. As far as we know, these redox preferences are opposite to almost all of the earlier reported cases, [5] where the low-temperature form is represented by the species with a more oxidized metal M n+1 and the hightemperature isomer has a reduced metal ion M n .…”

An Organoytterbium(III) Complex Exhibiting Field-Induced Single-Ion-Magnet Behavior

“…Unlike the previously reported related complexes coordinated by other DAD-based ligands, 8,9 this compound behaves as a field-induced SIM with a single relaxation process and constitutes the first example of an organoytterbium system exhibiting such a property. To gain further insights into the origin of such slow relaxation of the magnetization, the preparation of a series of neutral and ionic Yb 3+ complexes coordinated by DAD 2− and DAD •− ligands is pursued now in our laboratories.…”