1309834-01-2Relevant academic research and scientific papers
Structural effects of varied steric bulk in 2,(4),6-substituted dimethylthallium(III) phenoxides
Briand, Glen G.,Decken, Andreas,McKelvey, J. Ian,Zhou, Yukun
, p. 2298 - 2305 (2011)
The structural effects of varied steric bulk on 2,(4),6-substituted dimethylthallium(III) phenoxides has been examined. The facile reaction of Me3Tl with a series of 2,(4),6-substituted phenols in toluene or diethyl ether resulted in the formation of the species [Me2TlO(2,6- R2C6H3)]2 [R = H (4), Me (5), iPr (6), Ph (7)] and [Me2TlO(2,4,6-tBu3C6H 2)] (8). All compounds have been characterized by elemental analysis as well as their melting point; FTIR, FT-Raman, solution 1H and 13C{1H} NMR spectroscopy; and X-ray crystallography. The structures of 4-7 are dimeric through short intermolecular Tl-O interactions, which yield a symmetric Tl2O2 unit and a distorted seesaw C2O2 bonding environment for thallium. An increase in the steric bulk in 4-6 has little effect on Tl-O bond lengths, whereas the C Me-Tl-CMe bond angle was found to significantly decrease. Further, the phenoxide ligands in 5 and 6 were found to be oriented perpendicular to the Tl2O2 unit to minimize steric interactions. Alternatively, compound 7 shows an increase in Tl-O bond lengths and an increase in the CMe-Tl-CMe bond angle compared to 4-6, and orientation of the phenoxide ligands perpendicular to the Tl 2O2 core. The significant steric bulk imposed by the -O(2,4,6-tBu3C6H2) ligand in 8 precludes dimer formation and allows for isolation of a monomeric species that contains a three-coordinate T-shaped C2O bonding environment for thallium. DFT calculations show that the energetic favorability of dimer formation decreases with increased phenoxide steric bulk.
