Aluminum complexes with new non-symmetric ferrocenyl amidine ligands and their application in CO transformation into cyclic carbonates

A set of alkyl aluminum complexes supported by non-symmetric ferrocenyl amidine ligands were used as catalysts for the preparation of cyclic carbonates from epoxides and carbon dioxide using Bu 4 NI as a co-catalyst. A modified method for the synthesis of aminoferrocene allowed us to obtain this precursor in quantitative yield. Treatment of aminoferrocene with the corresponding acetimidoyl chloride afforded the desired ferrocenyl amidine ligands L 1 H , ( E )- N -(2,6-diisopropylphenyl)- N' -(ferrocenyl)acetimidamide, and L 2 H , ( E )- N -(2,6-dimethylphenyl)- N' -(ferrocenyl)acetimidamide. The reaction of these ligands with 1.0 or 0.5 equiv. of AlMe 3 led to the synthesis of aminoferrocene based aluminum complexes (( L 1 )AlMe 2 ( 1 ), ( L 2 )AlMe 2 ( 2 ), ( L 1 ) 2 AlMe ( 3 ), and ( L 2 ) 2 AlMe ( 4 )) in excellent yields, which were characterized by spectroscopic and X-ray diffraction methods. In addition, we have studied their electrochemical properties and complex 1 was found to be the most active catalyst for the formation of cyclic carbonates 6a-j from their corresponding epoxides 5a-j and CO 2 . A set of alkyl aluminum complexes supported by non-symmetric ferrocenyl amidine ligands were used as catalysts for the preparation of cyclic carbonates from epoxides and carbon dioxide using Bu 4 NI as a co-catalyst.