Sterically Demanding Chelating Diamide Complexes of Yttrium and Lutetium

Deprotonation of the bridged diamine ArHN(CH 2 ) 3 NHAr (Ar = 2,6- i Pr 2 C 6 H 3 ) with n -butyllithium and potassium hydride, respectively, gives the corresponding alkali metal derivatives M 2 {ArN(CH 2 ) 3 NAr} (M = Li ( 1a ), K ( 1b )). 1a reacts with yttrium trichloride to form the metalate complex [Y{ArN(CH 2 ) 3 NAr}(THF) 2 ( μ -Cl) 2 Li(THF) 2 ] ( 2 ). The coordination number of yttrium in 2 is six. The structure of 2 shows two bridging chloride ligands and an alkali metal bound by two solvate molecules. Further reaction of 2 with NaC 5 H 5 in THF affords the complex [Y{ArN(CH 2 ) 3 NAr}( η 5 -C 5 H 5 )(THF)] ( 4 ). The structure of 4 in solution and in the solid state is best described as a distorted tetrahedron. Reaction of 1b with anhydrous lutetium trichloride leads to the unexpected ionic product [LuCl 2 (THF) 5 ][Lu{ArN(CH 2 ) 3 NAr} 2 ] ( 5 ). 5 can be formally considered as a derivative of the ionic compound [LuCl 2 (THF) 5 ][LuCl 4 (THF) 2 ], in which all four chlorine atoms of the anion are substituted by 2 equiv of the {ArN(CH 2 ) 3 NAr} 2 - ligand. As seen from all three structures, the steric demand of the {ArN(CH 2 ) 3 NAr} 2 - ligand is less than that of two (C 5 Me 5 ) - moieties.