Group 4 metallocene complexes with pendant nitrile groups

The preparation of a new functionalized cyclopentadienyl ligand bearing a nitrile pendant substituent, (C 5 H 4 CMe 2 CH 2 CN) − is reported. The corresponding lithium salt of this ligand ( 1 ) was prepared by the reaction of in situ lithiated acetonitrile with 6,6-dimethylfulvene. The ligand was subsequently utilized for the synthesis of group 4 metal complexes [(η 5 –C 5 H 4 CMe 2 CH 2 CN) 2 MCl 2 ] (M = Ti, 2 ; M = Zr, 3 ; M = Hf, 4 ), [(η 5 –C 5 H 5 ) (η 5 –C 5 H 4 CMe 2 CH 2 CN)MCl 2 ] (M = Ti, 7 ; M = Zr, 8 ), and [(η 5 -C 5 Me 5 ) (η 5 C 5 H 4 CMe 2 CH 2 CN) 2 ZrCl 2 ] ( 9 ). Alternative route to 2 comprised the preparation of half-sandwich complex [(η 5 –C 5 H 4 CMe 2 CH 2 CN)TiCl 3 ] ( 6 ). The prepared compounds were characterized by common spectroscopic methods and the solid state structures of complexes 2 , 3 , 4 , 7 , and 9 were determined by the single-crystal X-ray diffraction analysis. In addition, compound 7 was converted to the corresponding dimethyl derivative [(η 5 –C 5 H 5 ) (η 5 –C 5 H 4 CMe 2 CH 2 CN)TiMe 2 ] ( 10 ) and also treated with the chloride anion abstractor Li[B(C 6 F 5 ) 4 ] to generate the cationic complex with the coordinated nitrile group, as suggested by the NMR spectroscopy. A formation of yet another cationic complex was observed upon treating compound 10 with (Ph 3 C)[B(C 6 F 5 ) 4 ].