The crystal and molecular structures (at –40 °C) of the tetrabenzyls of titanium, hafnium, and tin

Tetrabenzylhafnium has a molecular structure identical to that of tetrabenzylzirconium with a distorted tetrahedral arrangement of ligands around the metal and angles at the methylene carbons of around 90°; tetrabenzyltitanium shows a similar distortion from a tetrahedral arrangement but the angle M–CH2–C now averages 103°; an interacation between the aromatic ring and the transition-metal atoms is suggested to account for the distortion; in contrast, tetrabenzyltin has a perfectly regular structure.