CH Al2(CH3)6 CH3 A ACH3 3c-2eCH3桥cH CH H3 AL2(CH3)4Cl2 3c-4e(普通单键)Cl桥CH3 CH3 CH3 CH3 CH3 Al Al CH3 Al2 (CH3 )6 3c-2e CH3桥 Al2 (CH3 )4Cl2 3c-4e（普通单键）Cl桥