Coordination chemistry of group 4 metal compounds with mixed-ligand, silyl-linked bis(amidinate) ligand and cyclopentadienyl

• Published in: Inorganica Chimica Acta Vol. 362; no. 4; pp. 1143 - 1148
• Main Authors: Bai, Sheng-Di, Tong, Hong-Bo, Guo, Jian-Ping, Zhou, Mei-Su, Liu, Dian-Sheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 02.03.2009
• Subjects: Bis(amidinate); Cyclopentadienyl; Mixed-ligand; Titanium; Zirconium; Bis(amidinate); Titanium; Zirconium; Cyclopentadienyl; Mixed-ligand
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2008.05.038

In a class of group 4 metal compounds with the mixed-ligand environment, the tetradentate N-ligands, silyl-linked bis(amidinate) ligands, present the different bonding modes as variation of electronic and sterical properties of metal centers. The synthesis and characterization of a class of group 4 metal derivatives based on the silyl-linked bis(amidinate) ligands [SiMe 2{NC(Ph)N(2,6-R 2Ph)Li} 2] [ L 1 (R = H) and L 2 (R = Me)] are described. The metal salts coordinated with cyclopentadienyl were used in order to increase the steric hindrance and lower the Lewis acidity of metal centers, which could prevent the N-ligands from rearranging. The tetradentate ligands L 1 and L 2 reacted with TiCl 2(C 5H 5) 2 to give compounds 1 and 2 in tridentate and bidentate bonding modes, respectively. Treatment of the ligand L 1 with ZrCl 3(C 5H 5) produced the half-sandwich zirconium complex 3. Reactions of the ligands with ZrCl 2(C 5H 5) 2 afforded zirconium compounds 4 and 5, demonstrating the same geometry as 1. Comparing these analogous molecular structures, it suggests that the coordination modes of the N-ligands are variable according to the properties of the metal centers as well as the bulky hindrance of the terminal groups on the seven-membered N–C–N–Si–N–C–N backbone.