Oligosiloxanediols as building blocks for supramolecular chemistry: hydrogen-bonded adducts with amines form supramolecular structures in zero, one and two dimensions

The structure of 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol- pyrazine (4/1) , (C36H32O4Si3)(4). C4H4N2 (1), contains finite centrosymmetric aggregates; the diol units form dimers, by means of O-H ... O hydrogen bonds, and pair s of such dimers are linked to the pyrazine by means of O-H ... N hydrogen bonds. In 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol-pyridine (2/3), (C36H3 2O4Si3)(2).(C5H5N)(3) (2), the diol units are linked into centrosymmetric p airs by means of disordered O-H ... O hydrogen bonds: two of the three pyri dine molecules are linked to the diol dimer by means of ordered O-H ... N h ydrogen bonds, while the third pyridine unit, which is disordered across a centre of inversion, links the diol dimers into a C-3(3)(9) chain by means of O-H ... N and C-H ... O hydrogen bonds. In 1,1,3,3-tetraphenyldisiloxane -1,3-diolhexamethylenetetramine (1/1), (C24H22O3Si2). C6H12N4 (3), the diol acts as a double donor and the hexamethylenetetramine acts as a double acc eptor in ordered O-H ... N hydrogen bonds and the structure consists of C-2 (2)(10) chains of alternating diol and amine units. In 1,1,3,3-tetraphenyld isiloxane-1,3-diol-2,2'-bipyridyl (1/1), C24H22O3Si2. C10H8N2 (4), there ar e two independent diol molecules, both lying across centres of inversion an d therefore both containing linear Si-O-Si groups: each diol acts as a doub le donor of hydrogen bonds and the unique 2,2'-bipyridyl molecule acts as a double acceptor, thus forming C-2(2)(11) chains of alternating diol and am ine units. The structural motif in 1,1,3,3-tetraphenyldisiloxane-1,3-diol-p yrazine (C24H22O3Si2)(2).- C4H4N2 (5), is a chain-of-rings: pairs of diol m olecules are linked by O-H ... O hydrogen bonds into centrosymmetric R-2(2) (12) dimers and these dimers are linked into C-2(2)(13) chains by means of O-H ... N hydrogen bonds to the pyrazine units. 1,1,3,3-Tetraphenyldisiloxa ne-1,3-diol-pyridine (1/1), C24H22O3Si2. C5H5N (6), and 1,1,3,3-tetraphenyl disiloxane-1,3-diol-pyrimidine (1/1), C24H22O3Si2. C4H4N2 (7), are isomorph ous: in each compound the amine unit is disordered across a centre of inver sion. The diol molecules form C(6) chains, by means of disordered O-H ... O hydrogen bonds, and these chains are linked into two-dimensional nets buil t from R-6(6)(26) rings, by a combination of O-H ... N and C-H ... O hydrog en bonds.