DISILASELENIRANE AND DISILATELLURIRANE - SYNTHESIS AND CRYSTAL-STRUCTURES

Reaction of elemental selenium and tellurium with 1,1,2,2-tetramesityldisilene produces respectively 1,1,2,2-tetramesityl-1,2-disilaselenirane (3) and 1,1,2,2-tetramesityl-1,2-disilatellurirane (4). The structures of 3 and 4 are confirmed by X-ray crystal analysis. Crystals of 3 are monoclinic, space group P2(1)/c: a = 11.625 (4) angstrom, b = 8.896 (4) angstrom, c = 31.398 (10) angstrom; beta = 99.78 (3)-degrees; V = 3200 (2) angstrom3; d(calcd) = 1.270 g/mL for Z = 4; R = 5.67%; 3236 reflections with F > 4.0-sigma(F). Crystals of 4 are orthohombic, space group Pnn2: a = 18.516 (4) angstrom, b = 15.954 (3) angstrom, c = 11.917 (2) V = 3520.3 (12) angstrom3; d(calcd) = 1.329 g/mL for Z = 4; R = 5.18%; 2723 reflections with F > 4.0-sigma(F). The Si-Si bond lengths are 2.303 (3) angstrom for 3 and 2.337 (4) angstrom for 4. Both 3 and 4 have a nearly planar arrangement of C, C, Si atoms around each silicon atom. The spectroscopic and structural properties of 3 and 4 are presented along with those of 1,1,2,2-tetramesityl-1,2-disilaoxirane (1) and 1,1,2,2-tetramesityl-1,2-disilathiirane (2), the two other chalcogen derivatives with similar constitution.