Topochemical Anion Metathesis Routes to the $Zr_2N_2S$ Phases and the $Na_2S$ and ACl Derivatives (A = Na, K, Rb)

Stoltz, C and Ramesha, K and Sirchio, SA and Gonen, ZS and Eichhorn, BW and Salamanca-Riba, L and Gopalakrishnan, J (2003) Topochemical Anion Metathesis Routes to the $Zr_2N_2S$ Phases and the $Na_2S$ and ACl Derivatives (A = Na, K, Rb). In: Journal of the American Chemical Society, 125 (14). pp. 4285-4295.

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Abstract

Anion metathesis reactions between ZrNCl and A(2)S (A = Na, K, Rb) in the solid state follow three different pathways depending on reaction temperature and reactantbstoichiometry: (1) the reaction of ZrNCl with A(2)S in the 2:1 stoichiometry at 800 degreesC/72 h/in vacuo yields alpha-Zr2N2S with the expected layered structure of La2O2S. Above 850 degreesC, alpha-Zr2N2S (P (3) over bar m1; a = 3.605(1) Angstrom, c = 6.421(3) Angstrom) neatly transforms to beta-Zr2N2S (P6(3)/mmc: a = 3.602(l) Angstrom, c = 12.817(l) Angstrom). The structures of the alpha- and beta-forms are related by an a/2 shift of successive Zr2N2 layers. (2) The same reaction at low temperatures (300-400 degreesC) yields ACl intercalated phases of the formula A(x)Zr(2)N(2)SCl(x) (0 < x < similar to0.15), where alkali ions are inserted between the S/Cl...S/Cl van der Waals gap of a ZrNCl-type structure. The S and Cl ions are disordered and the c lattice parameters are alkali dependent (R (3) over barm, a similar to 3.6 Angstrom, c similar to 28.4 (Na), 28.9 (K), and 30.5 Angstrom (Rb). A(x)Zr(2)N(2)SCl, phases are hygroscopic and reversibly absorb water to give monohydrates. (3) Reaction of ZrNCl with excess A(2)S at 400-1000 degreesC gives A(2)S intercalated phases of the formula A(2alpha)Zr(2)N(2)S(1+x) (0 < X < 0.5), where the alkali ions reside between the S...S van der Waals gap of a ZrNCl type structure (R (3) over barm, a similar to 3.64 Angstrom, c similar to 29.48 Angstrom). Structural characterization of the new phases and implications of the results are described.

Item Type:	Journal Article
Publication:	Journal of the American Chemical Society
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	19 Nov 2009 09:07
Last Modified:	19 Sep 2010 04:57
URI:	http://eprints.iisc.ac.in/id/eprint/17434

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