A SYSTEMATIC SYNTHETIC APPROACH TO A NOVEL, MIXED 2,3-C2B4-ERBIUM(III) AND 2,4-C2B4-ERBIUM(III) CARBORANE BENT-SANDWICH COMPLEX

The reaction between closo-exo-Li(TMEDA)-1-Li(TMEDA)-2,3-(SiMe(3))(2)-2,3-C2B4H4 (1a) and anhydrous ErCl3, in a molar ratio of 2:1, in dry benzene at 0 degrees C produced, in 93% yield, a novel Er(III) bent-sandwich complex, [Li(TMEDA)(2)][1-Cl-1-(mu-Cl)-2,2',3,3'-(SiMe(3))(4)-5,6-[(mu-H)(2)Li(TMEDA)]-4,4',5'-[(mu-H)(3)Li(TMEDA)]-1,1'-commo-Er(2,3-C2B4H4)(2)] (2), as an orange crystalline solid. The reaction of 2 with 1 equiv of closo-exo-Li(TMEDA)-1-Li(TMEDA)-2,4-(SiMe(3))(2)-2,4-C2B4H4 (1b) in dry benzene at 0 degrees C produces the pink, dimeric Er(III) mixed-carborane bent-sandwich complex {Li(TMEDA)(2)}(2){commo-1-[2, 3-(SiMe(3))(2)-2,3-C2B4H4]-1-Er-[2,4-(SiMe(3))(2)-2,4-C2B4H4]}(2) (3) in 95% yield, thus demonstrating a possible general synthetic route to mixed-carborane metal complexes.