A Comparison of Analogous 4f- and 5f-Element Compounds: Syntheses, X-ray Crystal Structures and Catalytic Activity of the Homoleptic Amidinate Complexes [M{MeC(NCy)2}3] (M = La, Nd or U)

✍ Scribed by Claude Villiers; Pierre Thuéry; Michel Ephritikhine

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 187 KB
• Volume: 2004
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200400491

✦ Synopsis

Abstract

Reaction of UCl~4~ with [Li{RC(NCy)~2~}(THF)]~2~ (R = Me, 1a; R = __n__Bu, 1b) in THF gave the tris(amidinate) compounds [U{RC(NCy)~2~}~3~Cl] (R = Me, 2a; R = __n__Bu, 2b) which were reduced with lithium powder in THF to the homoleptic complexes [U{RC(NCy)~2~}~3~] (R = Me, 3a; R = __n__Bu, 3b). Complexes 1a, 1b, 2a and 3a have been crystallographically characterized. Comparison of the crystal structure of 3a with those of the lanthanide analogues [Ln{MeC(NCy)~2~}~3~] (Ln = La, 4; Ln = Nd, 5; Ln = Yb, 6) shows that the average U−N distance is shorter than expected from a purely ionic bonding model. The uranium complex 3a is much less efficient than its lanthanide counterparts in the catalytic polymerization of ϵ‐caprolactone because of its rapid oxidation into U^IV^ species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)