Reaction of 2,5-di- tert -butyl-3,4-dimethylphospholide potassium [K(Dtp)] with YCl 3 or SmI 3 (THF) 3.5 in THF followed by reaction with o- dimethylaminobenzylpotassium [K(CH 2 C 6 H 4 NMe 2 - o )] afforded the solvent-free mono(phospholyl)lanthanoid bis(benzyl) complexes [(Dtp)Ln(CH 2 C 6 H 4 NMe 2 - o )] (Ln = Y ( 3-Y ), Sm ( 3-Sm )). The Sc analogue could not be obtained under these conditions, as the reaction between K(Dtp) and ScCl 3 in THF led to the THF-ring-opened product [{Sc[μ-O(CH 2 ) 4 (Dtp)]Cl 2 (THF) 2 } 2 ] ( 5 ). Replacing THF by a mixture of toluene/pyridine gave [(Dtp)ScCl 2 (pyridine)] ( 6 ), which on further reaction with [K(CH 2 C 6 H 4 NMe 2 - o )] in toluene afforded [(Dtp)Sc(CH 2 C 6 H 4 NMe 2 - o ) 2 ] ( 3-Sc ). Protonation of [K(Dtp)] with p -toluenesulfonic acid gave the 1 H phosphole Dtp-H ( 7 ), which could not be isolated pure but is stable in solution at room temperature. 3-Sc could also be obtained from the reaction between the in-situ-prepared 7 and [Sc(CH 2 C 6 H 4 NMe 2 - o ) 3 ] in toluene. Complexes 3-Ln were activated with [Ph 3 C][B(C 6 F 5 ) 4 ] and tested in the syndiospecific polymerization of styrene. Whereas 3-Sm did not show any activity, 3-Y and 3-Sc gave good to excellent results.
No takes yet. Share an insight, caveat, or question.
Jaroschik et al. (2007) studied this question.