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The synthesis and characterization of sterically encumbered terphenyl compounds are described. These are 2,6-Dipp2C6H3I (Dipp = 2,6-i-Pr2C6H3-), 1, 2,6-Trip2C6H3I (Trip = 2,4,6-i-Pr3C6H2−), 2, and 1,3-Mes*C6H4 (Mes* = 2,4,6-t-Bu3C6H2-), 3, and the solvated metal derivatives Et2OLiC6H3-2,6-Trip2, 4, and Me2SCuC6H3-2,6-Trip2, 5. They were characterized by 1H and 13C NMR spectroscopy and, in the case of 3−5, by X-ray crystallography. The monomeric structures of 4 and 5 and the two-coordinate nature of the metals underline the very bulky characteristics of these ligands. In addition the isolation of 3 rather than the intended iodine derivative 2,6-Mes*2C6H3I suggests that the synthetic route to the precursor halides can be limited by very large ring substituents.
Schiemenz et al. (Tue,) studied this question.