Pyridine complexes of TaF4, MoF3, WF4 and ReF3

Complexes MF 4 ·2py (M=Ta, W) were obtained by treating MX 4 ·2py (XCl, Br) with anhydrous HF in pyridine solution. By fluorinating ReI 4 ·2py with TIF in the presence of a reducing agent, crystals of [Repy 4 F 2 ]I could be isolated from the reaction mixture. X-ray analysis showed the cation to possess D 4h symmetry with fluorine ligands in the trans position and all four pyridine rings coplanar with the ReF 2 axis. By treating MoCl 3 ·3py with anhydrous HF in the presence of pyridinium salts, the oligomeric species [(Mopy 3 F 2 ) n ] + X − were obtained.