INFLUENCE OF STERIC HINDRANCE ON CYCLODISILAZANE FORMATION FROM TETRACHLORODISILANES

The reaction of MesNHLi (Mes* = 2,4,6-tri-tert-butylphenyl) with (Mes SiCl2)2 (Mes = 2,4,6-trimethylphenyl) in THF led to the formation of t ri-tert-butylphenyl)-amino)-1,2-dimesityldisilane (1). The action of 2 equiv of MesNHLi on (t-BUSiCl2)2 in THF resulted in the formation of a 2:1 to 4:1 cis/trans mixture of no)-1,3-dimesityl-2,4-di-tert-butylc yclodisilazane (2a,2b). A 3:1 mixture of 2a and 2b was subsequently ch lorinated with N-chlorosuccinimide in benzene yielding a 3:1 cis/trans mixture of no)-1,3-dimesityl-2,4-di-tert-butylcyclodisilazane (3a, 3b ). The molecular structures of 2a and 3a 0.5C6H14 were determined by X -ray crystallographic analysis. Compounds 2a and 2b cocrystallized as a 85:15 mixture in the triclinic space group P1BAR with cell parameter s a = 8.609(2) angstrom, b = 10.084(2) angstrom, c = 20.333(5) angstro m, alpha = 101.75(2)-degrees, beta = 92.42(2)-degrees, gamma = 92.418( 16)-degrees, V = 1724.3(6) angstrom3, Z = 2, d(calcd) = 1.102 g/cm3, a nd R = 5.51%. Compound 3a.0.5C6H14 crystallized in the tetragonal spac e group P42(1)cBAR with cell parameters a = 17.2385(7) angstrom, c = 2 8.568(6) angstrom, V 8489.5(18) angstrom3, z = 8, d(calcd) = 1.017g/cm 3, and R = 6.08%.