Control of cerium oxidation state through metal complex secondary structures

Abstract

A series of alkali metal cerium diphenylhydrazido complexes, Mx(py)y[Ce(PhNNPh)4], M = Li, Na, and K, x = 4 (Li and Na) or 5 (K), and y = 4 (Li), 8 (Na), or 7 (K), were synthesized to probe how a secondary coordination sphere would modulate electronic structures at a cerium cation.

Dicerium letterbox-shaped tetraphenolates: f-block complexes designed for two-electron chemistry

“…The two ions in the middle of the skeleton of the structure, K4 and K5, coordinate to the phenyl linker via π interactions with an average distance of 2.868 Å and 3.046 Å, respectively. 9,15,16 One K + counter-cation sits in the lattice, coordinated by seven THF molecules, while the other occupies the centre of the 'letterbox' shaped rectangular void formed by the two Ce ions and the two pTP ligand platforms. The K + inside the letterbox has close contacts to one aryloxide oxygen atom from each Ce-coordinated pTP with a distance of 3.021(6) Å and an approximately η 6 -coordination to both phenyl groups of the platform giving a bent bis(arene) sandwich geometry, (right, Fig.…”

“…7,14 For example, the alkali metal Ce III ate complexes, [M 3 (THF) n ][Ce(BINOLate) 3 ] (M = Li, Na, K, and Cs, BINOLate = 1,1′-binaphtholate) are readily oxidised to form two types of stable Ce IV complexes. 15,16 There is a significant research effort to find complexes that can replace expensive platinum group metal homogeneous catalysts that have traditionally been used in so much of organic chemistry due to their useful and ready two-electron reaction processes, namely oxidative addition and reductive elimination. However, the 3d-metal analogues that are proposed as their obvious cheap, less-toxic replacements undergo one-electron redox processes, hampering progress in this area.…”

Analysis of Lanthanide-Radical Magnetic Interactions in Ce(III) 2,2′-Bipyridyl Complexes

“…65 The Ce(III)/Ce(IV) couple could not be identified for 2-4, which is unsurprising as the Ce(IV) oxidation state is usually stabilized in the presence of electron-rich donors. 66…”

Bright Photoluminescence of [{(Cp)2Ce(μ‐Cl)}2]: A Valuable Technique for the Determination of the Oxidation State of Cerium

“…[24] In fact, this peculiarity in the redox behavior of Ce-based organometallic coordination compounds makes them particularly attractive for applicationsa sp hotosensitizers, as shown by the detailed works from the Schelter group. [25][26][27][28][29][30][31][32] Photoluminescences pectroscopy is af easible and valuable alternative to more complicated techniques, such as XAS, which requires synchrotron radiation to gain an insighti nto the electronic nature of such complexes andt he oxidation states of the lanthanide elements. Of course, other techniques, such as electro-/magnetochemistry or absorption spectroscopy, are similarly operationally simple.…”