A multifunctional substituted cyclooctatetraene as a ligand in organosamarium chemistry

The reactivity of the multifunctionalized cyclooctatetraene Li-2(1,4-R2C8H6 ) (R = o-(dimethylsilyl)-N,N-dimethyl aniline) is reported. To obtain this ligand in large quantities, a new, safe, and convenient method for the prep aration of cyclooctatetraene was developed. The ionic complex [Li(diglyme)( 2)][{1,4-R2C8H6}(2)Sm-2(mu-Cl)(3)] was synthesized by the reaction of the l igand with SmCl3 and characterized by single-crystal X-ray diffraction. The anion of the new complex is an unique example of a dimeric organolanthanid e complex which is mu(2)-bridged by three chlorine atoms. In the solid stat e the donor functionality does not coordinate to the samarium center. As sh own by spin lattice relaxation experiments, there is a coordination of one amino group to the samarium atom in solution. Density functional theory (DF T) calculations show that this coordination might in principle be in an int ramolecular fashion. Reaction of Li-2(1,4-R2C8H6) with [(C8H8)SmI(THF)(2)] does not lead to a mixed-sandwich complex. By a ligand rearrangement the no nfunctionalized complex [Li(THF)(3){mu-(eta(2):eta(8)-C8H8)}Sm(C8H8)] was i solated and characterized by single-crystal X-ray diffraction analysis.