American Chemical Society
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Hydrothermal Synthesis, Crystal Structure, and Solid-State NMR Spectroscopy of a New Indium Silicate:  K2In(OH)(Si4O10)

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posted on 2003-05-28, 00:00 authored by Ling-I Hung, Sue-Lein Wang, Hsien-Ming Kao, Kwang-Hwa Lii
A new indium(III) silicate, K2In(OH)(Si4O10), has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the monoclinic space group P21/m (No. 11) with a = 11.410(1) Å, b = 8.373(1) Å, c = 11.611(1) Å, β = 112.201(2)°, and Z = 4. The structure, which is analogous to that of K2CuSi4O10, consists of unbranched vierer 4-fold chains of corner-sharing SiO4 tetrahedra running along the b axis linked together via corner sharing by chains of trans-corner-sharing InO4(OH)2 octahedra to form a 3-D framework which delimits 8-ring and 6-ring channels to accommodate K+ cations. The presence of hydroxyl groups is confirmed by IR spectroscopy. The 29Si MAS NMR exhibits four resonances at −88.6, −90.1, −97.4, and −98.2 ppm corresponding to four distinct crystallographic Si sites. A 1H → 29Si CP/MAS NMR experiment was performed to assign the four resonances.