Reactions of alkylalane diolates with water synthesis, characterisation and ε-caprolactone polymerisation activity of novel alane benzopinacolates

1,1,2,2-Tetraphenylethane-1,2-diol (benzopinacole) reacts with R3Al to yield the trinuclear complexes {R5Al3[OC(C6H5)2C(C6H5)2O]2} [where R = Me (1), R = Et (2)]. Reactions of compounds 1 and 2 with water results in an elimination of R3Al and formation of unusual binuclear products {R2Al2(THF)[OC(C6H5)2C(C6H5)2O]2} [3 (R = Me), 4 (R = Et)] and a complicated mixture of R3Al hydrolysis products. Compounds were characterised by spectroscopy and crystal structures of 1–3 have been determined by single crystal X-ray diffraction. Binuclear complexes 3 and 4 demonstrate efficient catalytic activity toward ring-opening polymerisation of ε-caprolactone.