Lutetium complexes with tetraphenylethylene dianion. Synthesis and structure

The reactions of dipotassium and disodium salts of the tetraphenylethylene dianion with LuCl₃(THF)₃ or CpLuCl₂(THF)₃ yielded the homoleptic ate-complexes Na(THF)₅]Lu(Ph₂CCPh₂)₂] (1) and K(THF)₅]Lu(Ph₂CCPh₂)₂] (2) or the heteroleptic complex CpLu(Ph₂CCPh₂)(THF)₂ (4), respectively. Recrystallization of complex 1 from a diglyme—THF mixture afforded Na(diglyme)₂]Lu(Ph₂CCPh₂)₂](THF)_0,5 (3). Recrystallization of complex 4 from 1,2-dimethoxyethane gave CpLu(Ph₂CCPh₂)(DME)](DME) (5). The structures of complexes 3 and 5 were established by X-ray diffraction analysis. In both complexes, the unusual η⁶-coordination of the (Ph₂CCPh₂)²⁻ dianion to lutetium is observed. The Lu-C distances vary from 2.441(2) to 2.643(2) Å (3) and from 2.470(3) to 2.763(3) Å (5). In complexes 3 and 5, a redistribution of the C-C bond lengths was observed in the Ph groups coordinated to lutetium. Studies by ¹H, ¹³C, and 2D NMR spectroscopy demonstrated that the η⁶-coordination of the tetraphenylethylene dianion in homoleptic ate-complexes 1 and 2 is retained in a THF solution, whereas the coordination of this dianion in heteroleptic complex 4 changes from η⁶ to η⁴.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2060–2068, October, 2004.