Solid state, structural and solution studies on bis(2-methylbenzyl)-selenide, methyl(2,4,6-tri-t-butylphenyl)-selenide, bis(2,4,6-tri-methylphenyl)-diselenide, and bis(2,4,6-tri-t-butylphenyl)-diselenide

Two selenides, (2-MeBz)(2)Se (1) and MeMes*Se (2) and two diselenides, Mes( 2)Se(2) (3) and Mes(2)*Se-2 (4) have been prepared and characterized by sin gle-crystal X-ray diffraction and by NMR spectroscopy. The structure of 1 w as solved in the orthorhombic space group Pbca (no. 61) with cell constants a = b = 13.944(10) Angstrom, c = 14.30(2) Angstrom. The structure of 2 was determined in space group P (1) over bar (no. 2) with cell constants a = 5 .9443(5) Angstrom, b = 18.665(2) Angstrom, c = 26.372(3) Angstrom, alpha = 99.393(2)degrees, beta = 90.890(2)degrees and gamma = 92.703(2)degrees. The structures of 3 and 4 were determined in the monoclinic space group P2(1)/ c (no. 14) with unit cell parameters for 3 of a = 6.333(1) Angstrom, b = 18 .370(4) Angstrom, c = 5.122(3) Angstrom, beta = 97.42(3)degrees and for 4, a = 11.359(5) Angstrom, b = 10.520(8) Angstrom, c = 30.22(2) Angstrom and b eta = 98.94(4)degrees. A rotational process has been studied in 4 and the k inetics and thermodynamic parameters for this process are determined from D NMR measurements using three different methods, measurement of coalescence temperatures, calculation of kinetic parameters using the line half-width a pproximation, and by full line shape analysis, The results from these three methods were compared. (C) 1999 Elsevier Science S.A. All rights reserved.