SrTi(IO₃)₆·2H₂O and SrSn(IO₃)₆: distinct arrangements of lone pair electrons leading to large birefringences

Abstract

The distinct arrangements of [IO3]− trigonal pyramids lead to larger birefringences in SrTi(IO3)6·2H2O and SrSn(IO3)6 than that in (H3O)2Ti(IO3)6.

Synthesis and Structure of a New Iodate Cs5[Sc2(IO3)9](IO3)2 with a Complex Framework Based on the Condensation of [Sc(IO3)6] Building Blocks

“…The first phase was known as the trigonal compound Sc(IO 3 ) 3, whose symmetry correlated with the morphology of the crystals. The second phase had a monoclinic cell with a = 21.4044(3), b = 10.86740 (14), c = 17.5707(3) Å, and β = 108.335(2) • . No such monoclinic unit was found for any compound in ICSD [30], so this phase was proposed as a new one.…”

“…Isolated [M(IO 3 ) 6 ] blocks of various symmetry are described for a series of compounds with tetravalent (M IV = Ti, Ge, Sn, Pt) or trivalent (M III = In, Sc, Fe, Ga) cations. Thus, in the group of structures of the general formula A 2 M(IO 3 ) 6 (A = Li, Na, K, Rb, Cs, Tl, Ag, H 3 O and M = Ti, Ge, Sn, Pt) [8][9][10][11][12][13][14], most compounds are trigonal and possess a centrosymmetric R-3 space group. However, structures with small Li + and Na + cations have a polar space group P6 3 and exhibit nonlinear optical properties as well as BaGe(IO 3 ) 6 •H 2 O [13], possessing noncentrosymmetric sp.gr.…”

“…R3. Compounds SrTi(IO 3 ) 6 •2H 2 O, SrSn(IO 3 ) 6 [14], BaTi(IO 3 ) 6 [15], and Ba 3 Ga 2 (IO 3 ) 12 [16] also consist of isolated [M(IO 3 ) 6 ] blocks and have similar structures with trigonal sp.gr. R-3.…”