Synthesis,characterization,and single crystal structure determination of an oxo-derivative of methylaluminum containing asymmetric carbon

Abstract

Dimeric dimethylaluminum compound, {Me₂Al[μ-OCH(CH₃)CH₂OCH₃]}₂, was synthesized by the reaction of trimethylaluminum and 1-methoxy-2-propanol, an alkoxyalcohol containing asymmetric carbon, and characterized by ¹H, ¹³C, and ²⁷Al NMR spectroscopy. The 1-methoxy-2-propoxodimethylaluminum, as shown by the single crystal structure determination, exists as a dimer in the solid-state in which the ether alkoxide ligand chelates to the aluminum atom. The solution structure was probed by ¹H, ¹³C, and ²⁷Al NMR spectroscopy and the results showed that the five-coordinate isomer is in equilibrium with the four-coordinate isomer. However, variable-temperature ²⁷Al NMR spectroscopy showed only the presence of five-coordinate isomer at −15^°C and below.