Metal-π Interactions Dominate in the Solid-State Structures of Molecular Heterobimetallic Alkali-Metal-Europium(II) Aryloxo Complexes

• Published in: Chemistry, an Asian journal an Asian journal, 2009-08, Vol.4 (8), p.1309-1317
• Main Authors: Deacon, Glen B., Junk, Peter C., Moxey, Graeme J.
• Format: Article
• Language: English
• Subjects: alkali metals; europium; heterobimetallic complexes; O ligands; pi interactions
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.200900176

Treatment of Eu metal, 2,6‐diphenylphenol (HOdpp), and MOdpp (M=Na, K) at elevated temperature in the presence of mercury afforded heterobimetallic complexes which were structurally characterized after crystallization from toluene. The structures of [MEu(Odpp)3]⋅nPhMe (M=Na, n=1, 1; K, n=2.5, 2) consist solely of bridging aryloxide ligands and feature extensive π‐Ph–metal interactions. Rather than a heterobimetallic species, treatment of Eu metal and HOdpp with LiOdpp under similar conditions afforded a number of products, including a mixed‐valent europium complex, [Eu2(Odpp)3][Eu(Odpp)4]⋅4 PhMe (3). The structural framework of the [Eu2(Odpp)3]+ cation of 3 is similar to that of the molecular heterobimetallics 1 and 2, including the presence of π‐Ph–Eu interactions. The reluctance of the reaction to provide a Eu/Li heterobimetallic complex was exemplified by the simultaneous crystallization of [Eu2(Odpp)4]⋅PhMe (6) and the homoleptic cubane [Li4(Odpp)4]⋅2 C6H14 (5) from toluene/hexane. Two of a (different) kind: Treatment of Eu metal and 2,6‐diphenylphenol (HOdpp) with MOdpp (M=Na, K) at 210 °C affords molecular heterobimetallic aryloxo complexes [MEu(Odpp)3] (see picture for M=Na), which were crystallographically characterized as their toluene solvates.