ABSTRACT: In the three sterically congested silanes, C24H38Si2 (1) (1,1,2,2-tetra-isopropyl-1,2-di-phenyl-disilane), C24H34Br4Si2 (2) [1,1,2,2-tetra-kis-(2-bromo-propan-2-yl)-1,2-di-phenyl-disilane] and C32H38Si2 (3) (1,2-di-tert-butyl-1,1,2,2-tetra-phenyl-disilane), the Si-Si bond length is shortest in (1) and longest in (2), with (3) having an inter-mediate value, which parallels the increasing steric congestion. A comparison of the two isopropyl derivatives, (1 and 2), shows a significant increase in the Si-C(ipso) distance with the introduction of bromine. Also, in the brominated compound 2, attractive inter-molecular Br⋯B
