Crystal structures and spectroscopic characterization of galactitol complexes of trivalent lanthanide and divalent alkaline earth chlorides

Crystal structures and FT-IR spectra of metal ion–galactitol (C6H14O6, the ligand here abbreviated as L) complexes: 2LaCl3·C6H14O6·10H2O and SrCl2·C6H14O6 complexes are reported. Crystal data of lanthanide chlorides (La3+, Nd3+, Sm3+, Eu3+, Tb3+)–galactitol complexes and alkaline earth chlorides (Ca2+, Sr2+)–galactitol complexes published earlier are summarized. Unlike other lanthanide ion–galactitol complexes (2MCl3·C6H14O6·14H2O), lanthanum ions give rise to two different structures: LaCl3·C6H14O6·6H2O (LaL1) and 2LaCl3·C6H14O6·10H2O (LaL2). Sr2+–galactitol complexes also crystallized with two structures: SrCl2·C6H14O6·4H2O (SrL1) and SrCl2·C6H14O6 (SrL2). These metal ions thus give different coordination structures with galactitol. The crystal structures and FT-IR spectra of lanthanide ion and alkaline earth ion–galactitol complexes were integrated to interpret the coordination modes of different metal ions. Similar IR spectra demonstrate the same coordination modes of the complexes.

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