Hybrid sandwich complexes: Mono(pentamethylcyclopentadienyl) η6-Tetraphenylborate complexes of divalent samarium and ytterbium

INOR 288

Timothy M. Champagne, tchampag@uci.edu1, Joseph W. Ziller, jziller@uci.edu2, and William J. Evans, wevans@uci.edu2. (1) Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025, (2) Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025
Organometallic divalent lanthanide chemistry has been heavily dominated by bis(pentamethylcyclopentadienyl) complexes of the type (C5Me5)2Ln. The absence of mono(pentamethylcyclopentadienyl) ligands in this area suggested that ligand redistribution occurred in mono(pentamethylcyclopentadienyl) systems to make the more favored metallocenes. We now find that surprisingly stable mono(pentamethylcyclopentadienyl) divalent lanthanides can be isolated by protonolysis of the (C5Me5)1- ligand in (C5Me5)2Yb and (C5Me5)2Sm with [Et3NH][BPh4]. In each (C5Me5)Ln(μ-η6:η1-C6H5)2B(C6H5)2 product, the tetraphenylborate ligates the divalent metal with two hexahapto phenyl rings. Addition of THF provided with the first examples of solvated mono(pentamethylcyclopentadienyl) lanthanide complexes of the form (C5Me5)Ln(THF)(μ-η1:η6-Ph)(μ-η1:η2-Ph)BPh2 and [(C5Me5)Ln(THF)4][BPh4]. These complexes can also be obtained from (C5Me5)2Ln(THF)2 and [Et3NH][BPh4]. Reaction of (C5Me5)Sm(μ-η6:η1-C6H5)2B(C6H5)2 with azobenzene generates a radical anion complex, (C5Me5)Ph3B(μ-η1:η6-Ph)Sm(η2-N2Ph2), that retains the hybrid sandwich ligation around the metal. However, reaction with cyclooctatetraene (COT) leads to ligand redistribution and formation of [(C5Me5)2Sm][(μ-Ph)BPh2] and (C5Me5)Sm(COT). Reactivity patterns of these complexes will be described.
 

Lanthanides and Actinides
7:00 PM-10:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster

Division of Inorganic Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006