Vibrational behavior of SO42- guest ions included in K2Me(CrO4)2·2H2O (Me = Co, Ni) and crystal structures of K2Me(CrO4)2·2H2O (Me = Co, Ni)

The influence of the metal ion nature (Me2+ and Me+) on the values of Δν3 and Δνmax of matrix-isolated SO42- ions in different matrices with kröhnkite-type octahedral-tetrahedral chains - chromates K2Me(CrO4)2·2H2O (Me = Mg, Co, Ni, Zn, Cd) and selenates Na2Me(SeO4)2·2H2O (Me = Co, Ni, Zn, Cd) is analyzed. SO42- guest ions included in chromate matrices K2Me(CrO4)2·2H2O (Me = Co, Ni, Cd) are remarkably less distorted than in selenate ones Na2Me(SeO4)2·2H2O (Me = Co, Ni, Cd) as deduced from the values of Δν3 and Δνmax owing to weaker static fields caused by the larger K+ ions as compared to that caused by the smaller Na+ ions. The strength of the hydrogen bonds in the title compounds, i.e. the frequencies of νOD (matrix-isolated HDO molecules) is discussed in terms of hydrogen bond distances Ow···O, proton acceptor capacity of the oxygen atoms deduced from their bond-valence sums and Me-OH2 interactions (synergetic effect).