| 초록 |
Two new bis(amidine) cobalt (II) complexes were rationally designed and synthesized in efficient ways. The firstly synthesized cobalt complex was based on a cyclic bisamidine ligand with chiral vicinal diphenyl groups. The structure was undoubtedly verified by single crystal X-ray crystallography. The Co-N bonds in this complex were significantly shorter than those found in the corresponding 1,2-diimine cobalt complex. This fact indicates that bis(amidine) ligand has better electron donacity than 1,2-diimine ligand. Upon test polymerization reaction of styrene, this complex exhibited moderate activity of 5.88x105 gPS/(mol Co h). Based on this result, a new 1,2-diaminobenzene-originated bisamidine ligand was synthesized and used to make another cobalt (II) complex. This catalyst showed unusually high polymerization activity [164x105 gPS/(mol Co h)] and high conversion (99%). The enhanced styrene polymerization activity is attributed to the improved electron donacity of the ligand. |
