Crystal structures of three sterically congested disilanes.
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, (1and2), shows a significant increase in the Si-C(ipso) distance with the introduction of bromine. Also, in the brominated compound2, attractive inter-molecular Br⋯Br inter-actions exist with Br⋯Br separationsca0.52 Å shorter than the sum of the van der Waals radii. In compound2, one of the bromo-isopropyl groups is rotationally disordered in an 0.8812 (9):0.1188 (9) ratio. Compound3exhibits 'whole mol-ecule' disorder in a 0.9645 (7):0.0355 (7) ratio with the Si-Si bonds in the two components making an angle ofca66°.
Department of Chemistry, Tulane University, New Orleans, LA 70118, USA.
Kothanda Rama
KR
Pichaandi
Department of Chemistry, Tulane University, New Orleans, LA 70118, USA.
Joel T
https://orcid.org/0000-0003-3488-1945
JT
Mague
Department of Chemistry, Tulane University, New Orleans, LA 70118, USA.
Mark J
https://orcid.org/0000-0003-4286-6200
MJ
Fink
crystal structure; disilane; halogen–halogen inter­action