Carbon is not the initial site of attack in the protonation of an allene ligand to give an η 2-vinyl species: kinetic studies on trans-[ [formula omitted]CPh)- (Ph 2PCH 2CH 2PPh 2) 2

Abstract

The reaction between trans-[ ReCl (CH 2C(CHPh)(dppe) 2] (dppe = Ph 2PCH 2CH 2PPh 2) and anhydrous HCl in tetrahydrofuran to give trans-[ ReCl {C(CH 2Ph)CH 2}(dppe) 2] + is associated with a complicated rate law which is inconsistent with a simple, direct protonation at the phenyl-substituted carbon atom. A mechanism is proposed involving initial protonation of the metal, followed by intramolecular and acid-base catalysed rearrangements. This mechanism is consistent with earlier extended Hückel calculations which indicate that the HOMO of the complex is predominantly metal-based.