Abstract
The title compounds {systematic names (E)-[diazene-1,2-diylbis(3,1-phenyl-ene)]bis-(di-methyl-silanol) and (E)-[diazene-1,2-diylbis(4,1-phenyl-ene)]bis-(di-methyl-silanol)}, both of the sum formula C16H22N2O2Si2, were obtained by transmetallation of the respective bis-stannylated azo-benzenes with di-chloro-dimethyl-silane and esterification followed by hydrolysis. The asymmetric unit of 3,3'-diazenediylbis[dimeth-yl(phen-yl)silanol] (with the silanol functional group in a meta position) consists of two mol-ecules, of which one occupies a general position, whereas the second is located on a centre of inversion. In 4,4'-diazenediylbis[dimeth-yl(phen-yl)silanol] (with the silanol functional group in a para position) likewise two mol-ecules are present in the asymmetric unit, but in this case both occupy general positions. Differences between all mol-ecules can be found in the torsions about the N=N bond, as well as in the dihedral angles between the benzene rings. In both structures, inter-molecular O-H⋯O hydrogen bonding is observed, leading to the formation of layers parallel to (01-1) for (I) and to chains parallel to the a axis for (II).