Steric effects in alkylalane dioldiates

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

“…Typical trinuclear complexes of trimethyl-, triethyl-and tri-iso-butylaluminium with diols recently reported the reaction of t Bu 3 Al with sterically crowded aliphatic diol (2,4-dimethylpentane-2,4-diol) as a route to the unusual dimeric product { t BuAl-[OC(CH 3 ) 2 CH 2 C(CH 3 ) 2 O]} 2 with two four-coordinated aluminium atoms [20]. However this product is stable in the presence of Lewis bases and inactive toward ecaprolactone polymerisation.…”

Sterically crowded diolates of group 13 metals

“…The presence of a broad signal at 3.87 ppm of two alcohol protons in the 1 H NMR spectrum of 1 indicates the absence of interand intramolecular hydrogen bonds. In recent years, it has been demonstrated that the signals of highly acidic protons involved in intramolecular hydrogen bonds in binuclear alane and gallane diolates {R 4 M 2 [diol-(H)] 2 } are shifted downfield (14-17 ppm) [6,7]. The (CH 3 ) 3 CGa protons, CH 2 and (CH 3 ) 2 C protons of the diol units of 1 are equivalent and appear in the 1 H NMR spectrum as singlets at 1.42, 1.24 and 1.09 ppm, respectively.…”

“…{ t BuAl[OC(CH 3 ) 2 CH 2 C(CH 3 ) 2 O]} 2 , t Bu 3 Ga and t Bu 3 In were synthesised as described in the literature [6,18,19]. 1 H and 13 C NMR spectra were run on a Mercury-400BB spectrometer.…”

“…The 1 H NMR spectrum of the residue showed that the product 3 was formed almost quantitatively. X-ray quality crystals were obtained from n-C 6 A solution of 2,4-dimethylpentane-2,4-diol (0.528 g, 4 mmol) in 10 cm 3 of Et 2 O was added dropwise to a Et 2 O solution of t Bu 3 In (1. 144 g, 4 mmol), at )76°C.…”

“…The product 4 was isolated by crystallisation from n-C 6 H 14 solution (0.605 g, yield 42%). A small amount of X-ray quality crystals was obtained by recrystallisation from C 6 …”