Organometallic Cerium Complexes from Tetravalent Coordination Complexes

✍ Scribed by Polly L. Arnold; Ian J. Casely; Sergey Zlatogorsky; Claire Wilson

• Book ID: 102253718
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: German
• Weight: 408 KB
• Volume: 92
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200900152

✦ Synopsis

Abstract

The use of tetravalent cerium alkoxides, nitrates, and triflates was studied as a direct route to [Ce^IV^(carbene)] complexes. Protonolysis reactions between 1__H__‐imidazolium‐ or imidazoline (=4,5‐dihydro‐1__H__‐imidazole)‐containing alkoxide proligands HL (L=OCMe~2~CH~2~[1‐C(NCHCHN^i^Pr)]) and HL^S^ (L^S^=OCMe~2~CH~2~[1‐C(NCH~2~CH~2~N^i^Pr)]) and Ce^IV^ tert‐butoxide, triflate, and nitrate compounds were studied to target [Ce^IV^(N‐heterocyclic carbene)] complexes (of unsaturated and saturated carbenes, resp.). Instead, tetravalent cerium imidazolium [(O^t^Bu)~3~Ce(μ‐O^t^Bu)~2~(μ‐HL)Ce(O^t^Bu)~3~], or imidazolinium adducts [(O^t^Bu)~3~Ce(μ‐O^t^Bu)~2~(μ‐HL^S^)Ce(O^t^Bu)~3~] were isolated. However, the salt metathesis of cerium triflate with KL provided a simple route to [CeL~4~], which was significantly improved if an external oxidant, benzoquinone, was included in the mixture to maintain oxidation‐state integrity. Likewise, the salt metathesis of cerium triiodide with KL and added benzoquinone provided a straightforward route to [CeL~4~].