Syntheses and Reactions of Derivatives of (Pyrrolylaldiminato)germanium(II) and -Aluminum(III)

Abstract

(Pyrrolylaldiminato)germanium(II) chloride, LGeCl (1), was prepared by reacting LLi (L = 2-(ArN= CH)-5-tBuC(4)H(2)N; Ar = 2,6-iPr(2)C(6)H(3)) with 1 equiv of GeCl2.(dioxane). Treatment of LGeCl (1) with KOtBu or LiN(H)Ar yielded LGeR (R = OtBu (2), N(H)Ar (3)) by halide metathesis. (Pyrrolylaldirninato)methylaluminum chloride, LAlMe(Cl) (4), was obtained from the reaction of LLi and MeAlCl2 or by treating LH with Me2AlCI in toluene. Treatment of LH with Me2AlCl or AlCl3 in Et2O at -18 degrees C resulted in the 1:1 adducts LH.AlMe2Cl (5) and LH.AlCl3 (5), respectively. Further reaction of 4 with 2 equiv of LiNEt2 led to the insertion of the NEt2 group into the C=N bond together with the elimination of LiCl, to afford L'(NEt2)AlMe(NEt2)Li(THF) (6). Similarly, treatment of 4 with 2 equiv of LiPPh2(THF)(2) gave L'(PPh2)AlMe(OC4H8-PPh2)Li(THF)(2) (7) accompanied by ring opening of THF. Single-crystal X-ray structure determinations revealed that 3 and 4 each contained enantiomeric pairs, while 6 and 7 each adopted a single enantiomer.