HYDROGEN-BONDING .57. STOICHIOMETRY AND IR-SPECTRA OF THE LOWER HYDRATES OF N,N'-DIMETHYLTRIETHYLENEDIAMMONIUM, DECAMETHONIUM, HEXAMETHONIUM, AND (ATTEMPTED) N,N,N',N'-TETRAMETHYLPIPERAZINIUM HYDROXIDES

We have examined the lower hydroxide hydrates of the dipositive quater nary ammonium ions N,N'-dimethyltriethylenediammonium (DMTED2+), decam ethonium (DMO2+), hexamethonium (HMO2+), and (attempted) N,N,N',N'-tet ramethylpiperazinium (TMP2+). TMP(OH)2 cannot be prepared; the cation is destroyed by concentrated aqueous OH- through E2 reactions. Since T MPF2.2H2O can be prepared, this demonstrates the greater facility of O H- over F- in such eliminations. DMTED(OH)2 forms a hexahydrate (OH-.3 H2O) and a tetrahydrate (OH-.2H2O), DMO(OH)2 forms a hexahydrate and a dihydrate (OH-.H2O), and HMO(OH)2 forms a hexahydrate, a trihydrate ( OH-.1.5H2O), a dihydrate, and possibly a fourth hydrate, HMO(OH)2.4.5H 2O. The two hydroxide hydrates of DMTED(OH)2 give poorly resolved IR s pectra which shows that free (not hydrogen bond donor) OH- is present in the tetrahydrate and H2O...HOH...OH2 bridges are present in both. T he four hydroxide hydrates of HMO(OH)2 all contain very tightly bound H2O with no H2O...HOH...OH2 bridges. Free OH- is present in all four h ydrates. The hexahydrate appears to contain a water-hydroxide structur e similar to that found in tetraethylammonium hydroxide trihydrate, wh ile the trihydrate shows a modified form of this structure. The IR spe ctrum of the dihydrate is consonant with the presence of planar (H2O.O H-)2 clusters. The hexahydrate of DMO(OH)2 has a generic framework cla thrate spectrum, while the dihydrate has spectral properties similar t o those of HMO(OH)2.2H2O.