Conformation-aggregation interplay in the simplest aliphatic ethers probed under high pressure

The structures of the simplest symmetric primary ethers [(CnH2n+1)(2)O, n = 1-3] determined under high pressure revealed their conformational preferences and intermolecular interactions. In three new polymorphs of diethyl ether (C2H5)(2)O, high pressure promotes intermolecular CH center dot center dot center dot O contacts and enforces a conversion from the trans-trans conformer present in the alpha, beta and gamma phases to the trans-gauche conformer, which is higher in energy by 6.4 kJ mol(-1), in the delta phase. Two new polymorphs of dimethyl ether (CH3)(2)O display analogous transformations of the CH center dot center dot center dot O bonds. The crystal structure of di-n-propyl ether (C3H7)(2)O, determined for the first time, is remarkably stable over the whole pressure range investigated from 1.70 up to 5.30 GPa.