Issue 12, 2015

Isolation of +2 rare earth metal ions with three anionic carbocyclic rings: bimetallic bis(cyclopentadienyl) reduced arene complexes of La2+ and Ce2+ are four electron reductants

Abstract

A new option for stabilizing unusual Ln2+ ions has been identified in the reaction of Cp′3Ln, 1-Ln (Ln = La, Ce; Cp′ = C5H4SiMe3), with potassium graphite (KC8) in benzene in the presence of 2.2.2-cryptand. This generates [K(2.2.2-cryptand)]2[(Cp′2Ln)2(μ-η66-C6H6)], 2-Ln, complexes that contain La and Ce in the formal +2 oxidation state. These complexes expand the range of coordination environments known for these ions beyond the previously established examples, (Cp′′3Ln)1− and (Cp′3Ln)1− (Cp′′ = C5H3(SiMe3)2-1,3), and generalize the viability of using three anionic carbocyclic rings to stabilize highly reactive Ln2+ ions. In 2-Ln, a non-planar bridging (C6H6)2− ligand shared between two metals takes the place of a cyclopentadienyl ligand in (Cp′3Ln)1−. The intensely colored (ε = ∼8000 M−1 cm−1) 2-Ln complexes react as four electron reductants with two equiv. of naphthalene to produce two equiv. of the reduced naphthalenide complex, [K(2.2.2-cryptand)][Cp′2Ln(η4-C10H8)].

Graphical abstract: Isolation of +2 rare earth metal ions with three anionic carbocyclic rings: bimetallic bis(cyclopentadienyl) reduced arene complexes of La2+ and Ce2+ are four electron reductants

Supplementary files

Article information

Article type
Edge Article
Submitted
09 Jul 2015
Accepted
18 Sep 2015
First published
21 Sep 2015
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2015,6, 7267-7273

Author version available

Isolation of +2 rare earth metal ions with three anionic carbocyclic rings: bimetallic bis(cyclopentadienyl) reduced arene complexes of La2+ and Ce2+ are four electron reductants

C. M. Kotyk, M. E. Fieser, C. T. Palumbo, J. W. Ziller, L. E. Darago, J. R. Long, F. Furche and W. J. Evans, Chem. Sci., 2015, 6, 7267 DOI: 10.1039/C5SC02486B

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