Département de chimie moléculaire

Organozinc hydroxides, RZnOH, possessing the proton-reactive alkylzinc group and the CO2-reactive Zn-OH group, represent an intriguing group of organometallic precursors for the synthesis of novel zinc carbonates. Comprehensive exptl. and computational studies on (1) soln. and solid-state behavior of Me3CZnOH (1) species in the presence of Lewis bases, namely, THF and 4-methylpyridine; (2) step-by-step sequence of the reaction between 1 and CO2; and (3) the effect of a donor ligand and/or an excess of (Me3C)2Zn as an external proton acceptor on the reaction course are reported. DFT calcns. for the insertion of carbon dioxide into the dinuclear alkylzinc hydroxide 12 are fully consistent with 1H NMR spectroscopy studies and indicate that this process is a multistep reaction, in which the insertion of CO2 seems to be the rate-detg. step. Also, DFT studies show that the mechanism of the rearrangement between key intermediates, i.e., the primary alkylzinc bicarbonate with a proximal position of hydrogen and the secondary alkylzinc bicarbonate with a distal position of hydrogen, most likely proceeds through internal rotation of the dinuclear bicarbonate. [on SciFinder(R)]