Double salt crystal structure of hexa-sodium hemiundeca-hydrogen α-hexa-molybdoplatinate(IV) heminona-hydrogen α-hexa-molybdoplatinate(IV) nona-cosa-hydrate: di-hydrogen disordered-mixture double salt.

Hea-Chung Joo,Ki-Min Park,Uk Lee

doi:10.1107/s2056989015017703

Abstract

The title double salt containing two distinct, differently protonated hexa-molybdoplatinate(IV) polyanions, Na6[H5.5 α-PtMo6O24][H4.5 α-PtMo6O24]·29H2O, has been synthesized by a hydro-thermal reaction at ca pH 1.80. The positions of the H atoms in the polyanions were established from difference Fourier maps and confirmed by the inter-polyanion hydrogen bonds, bond-distance elongation, and bond-valence sum (BVS) calculations. The fractional numbers of H atoms in each polyanion are required for charge balance and in order to avoid unrealistically short H⋯H distances in the inter-polyanion hydrogen bonds. Considering the disorder, the refined formula of the title polyanion, {[H5.5 α-PtMo6O24]; polyanion (A) and [H4.5 α-PtMo6O24]; polyanion (B)}(6-), can be rewritten as a set of real formula, viz. {[H6 α-PtMo6O24]; polyanion (A). [H4 α-PtMo6O24]; polyanion (B)}(6-) and {[H5 α-PtMo6O24]; polyanion (A). [H5 α-PtMo6O24]; polyanion (B)}(6-). The polyanion pairs both form dimers of the same formula, viz. {[H10 α-Pt2Mo12O48]}(6-) connected by seven inter-polyanion O-H⋯O hydrogen bonds.

Highlights

The title double salt containing two distinct, differently protonated hexamolybdoplatinate(IV) polyanions, Na6[H5.5-PtMo6O24][H4.5-PtMo6O24]Á29H2O, has been synthesized by a hydrothermal reaction at ca pH 1.80
The positions of the H atoms in the polyanions were established from difference Fourier maps and confirmed by the interpolyanion hydrogen bonds, bonddistance elongation, and bond-valence sum (BVS) calculations
The fractional numbers of H atoms in each polyanion are required for charge balance and in order to avoid unrealistically short HÁ Á ÁH distances in the interpolyanion hydrogen bonds

Summary

Chemical context

The (planar structure) – (bent structure) – geometrical isomerization, according to stepwise protonation in the [PtMo6O24]8À polyoxometalate (POM) species, viz. ([H3.5-PtMo6O24]4.5À (Lee & Sasaki, 1994; Lee, 1988) , [H4-PtMo6O24]4À (Lee & Sasaki, 1994; Joo et al, 1994) and [H4.5-PtMo6O24]3.5À (Lee & Sasaki, 1994; Lee et al, 2010; Joo et al, 2015a) is an unprecedented phenomenon in the Anderson-type heteropolyanion (Anderson, 1937) and as well as in the chemistry of POMs. ([H3.5-PtMo6O24]4.5À (Lee & Sasaki, 1994; Lee, 1988) , [H4-PtMo6O24]4À (Lee & Sasaki, 1994; Joo et al, 1994) and [H4.5-PtMo6O24]3.5À (Lee & Sasaki, 1994; Lee et al, 2010; Joo et al, 2015a) is an unprecedented phenomenon in the Anderson-type heteropolyanion (Anderson, 1937) and as well as in the chemistry of POMs. In addition, differently protonated polyanion species have been reported, viz. [H2-PtMo6O24]6À (Lee & Joo, 2000; Lee & Joo, 2004), and [H6-PtMo6O24]2À (Lee & Joo, 2006a; Lee & Joo, 2006b; Lee & Joo, 2010) These polyanions form dimers by effective interpolyanion hydrogen bonds.

Structural commentary

Refinement