Polar Noncentrosymmetric ZnMoSb2O7 and Nonpolar Centrosymmetric CdMoSb4O10: d10 Transition Metal Size Effect Influencing the Stoichiometry and the Centricity

Two new quaternary molybdenum(VI) antimony(III) oxides, ZnMoSb2O7 and CdMoSb4O10, have been synthesized in phase-pure form. The title compounds consist of highly polarizable cations, i.e., d(10) (Mo6+) and d(10) (Zn2+ or Cd2+), and lone-pair cations (Sb3+). ZnMoSb2O7 exhibits a three-dimensional framework with ZnO4, MoO4, and SbO4 polyhedra in the polar space group P2(1), whereas CdMoSb4O10 exhibits one-dimensional tubule structures with CdO6, MoO4, and SbO3 polyhedra in the space group P2(1)/m. Several synthetic efforts suggest that the the dissimilar radii of Zn2+ and Cd2+ that can accommodate polyhedra of Sb3+ cations influence the stoichiometry as well as the centricity for the reported materials. Spectroscopic, thermal, and elemental analyses are reported along with dipole moment calculations. Nonlinear optical properties and their structural origin are examined for polar ZnMoSb2O7 as well.