Synthesis of Nickel Double-decker Complexes Containing 1,4-Dibora-2,5-cyclohexadiene Derivatives as Ligand

Abstract

η 5 -Cyclopentadienyl)(η 6 -1,2,3,4-tetramethyl-1,4-dibora-2,5-cyclohexadiene)Ni (5) (η 5 -Cyclopentadienyl)(η 6 -1,2,3,4-tetramethyl-1,4-dibora-2,5-cyclohexadiene)Ni (5) was synthesized as a main product by the reaction of cyclopentadienyl(carbonyl)nickel dimer and 1,2,3,4-tetramethyl-1,4-dibora-2-cyclohexene (1). Di-allyl nickel reacted with 2,3-diethyl-1,4-di-methyl-1,4-dibora-2-cyclohexene (2) at − 20 o C to give bis(η 6 -2,3-diethyl-1,4-dimethyl-1,4-dibora-2,5-cyclohexadiene)nickel (6) in the yield of 15%. By the reaction of di-allyl nickel and 2,3-dimethyl-1,4-diethoxy-1,4-di-bora-2-cyclohexene (3) at −20 o C bis[η 6 -2,3-dimethyl-1,4-diethoxy-1,4-di-bora-2,5-cyclohexadiene]nickel (7) was obtained in 22% yield. These double-decker complexes were difficult to separate because of their unstabilities and were identified by ESR, NMR, MS and elemental analysis, etc.