Nonlinear optical properties of strontium tartrato-antimonate(III) dihydrate, Sr[Sb2{(+)-C4H2O6}2]·2H2O

Stacking changes of KLi[Sb2(C4H2O6)2] homochiral layers mediated by interlayer solvent molecules

A new compound KLi[Sb2(C4H2O6)2]·4H2O, 1, was synthesized in single crystal form by slowly evaporating an aqueous solution of potassium antimony tartrate and lithium nitrate. The structure of 1 consists of homochiral layers of antimony tartrate dimers linked by LiO4 tetrahedra. The interlayer water molecules can be reversibly driven out by heating or exchanged by small alcohol molecules under ambient conditions, occurring via single-crystal to single-crystal transformations. To accommodate different interlayer molecules, the interlayer space is changed by adjusting the relative lateral shift of neighboring layers. A similar adjustment in the layer stacking also occurs in a structural phase transition caused by order-disorder transformation of the arrangement of interlayer methanol molecules at low temperature.

Synthesis and structural phase transitions of [Mg2Sb2(C4H2O6)2(H2O)8](ClO4)2·5H2O with complex homochiral chains

A new magnesium antimony tartrate perchlorate [Mg2Sb2(C4H2O6)2(H2O)8](ClO4)2·5H2O, 1, was synthesized in single crystal form by slowly evaporating an aqueous solution of potassium antimony tartrate and magnesium perchlorate. In the temperature interval 298 K–123 K, the compound undergoes two reversible structural phase transitions. The transition from phase I to phase II at ca. 236 K is second order and the transition from phase II to phase III at ca. 144 K is first order. Phase I has an orthorhombic structure, P21212, a=11.8658(4) Å, b=16.464(1) Å, c=8.3895(4) Å at 298 K, containing infinite chains of antimony tartrate dimeric clusters bridged by MgO2(H2O)4 octahedra. The ClO4 − anions occupying the interchain space show pronounced dynamic disorder. Phase II is monoclinic, P21, a=8.3813(8) Å, b=11.760(1) Å, c=16.289(2) Å, β=92.442(2)° at 153 K. Phase III has an orthorhombic unit cell with quadrupled cell volume, P212121, a=11.6914(8) Å, b=16.176(1) Å, c=33.426(2) Å at 123 K. While the infinite chains in phases II and III are closely similar to those in phase I, the ClO4 − anions show different orientations and gradual disappearance of dynamic disorder as the temperature is lowered.