6533b830fe1ef96bd1297c9c

RESEARCH PRODUCT

Syntheses, crystal structures, and solid state NMR investigations of K4M2P6S25 and K3M2P5S18 (M=Ti, Sn)

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Abstract Reaction of K 2 S 5 with P 4 S 10 and Ti at 450 °C results in the formation of K 4 Ti 2 P 6 S 25 , a new titanium thiophosphate, whose crystal structure was solved by single-crystal X-ray diffraction. The title compound crystallizes in the orthorhombic space group Fdd2, with the lattice constants a =33.819(7), b =35.508(7), and c =6.251(1) A ( Z =8). The structure contains a layered arrangement of crosslinked quasi-one-dimensional Ti 2 P 6 S 4− 25 chains. The K + ions are situated between the layers. The Ti atoms within the chains are octahedrally coordinated by P 2 S 4− 7 and P 2 S 4− 9 ligands. Reaction of K 2 S with P 4 S 10 , S and Ti at 600 °C results in the formation of K 3 Ti 2 P 5 S 18 , a novel titanium thiophosphate, which crystallizes in the monoclinic space group C2/c, with a =22.739(5), b =6.058(1), c =20.440(4) A, and β =105.41(3)° ( Z =4). The structure contains linear Ti 2 P 5 S 3− 18 chains with the K + ions situated between the chains. The Ti atoms within the chains are octahedrally coordinated by PS 3− 4 and P 2 S 4− 7 ligands. Reaction of K 2 S with P 4 S 10 , S and Sn at 600 °C results in the formation of the isostructural compound K 3 SnP 5 S 18 , a novel tin thiophosphate, with the lattice parameters a =23.303(7), b =6.023(2), c =20.888(6) A, and β =106.18(2)°. The spectroscopic characteristics of the thiophosphate groups, in particular that of the novel P 2 S 4− 9 entity are examined by UV–VIS, FT–IR and 31 P one- and two-dimensional magic-angle spinning (MAS-) NMR studies. The NMR experiments illustrate the utility of double-quantum coherence techniques as a unique tool of site assignments based on 31 P– 31 P spatial proximity, allowing a spectroscopic distinction of the P 2 S 4− 7 and the P 2 S 4− 9 groups can be differentiated based on their different chemical shift anisotropies.