Lewis Base Mediated Polymorph Selectivity of Pyrite CuSe2 through Atom Transfer in Solid-State Metathesis

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• 作者：Andrew J. Martinolich ; Robert F. Higgins ; Matthew P. Shores ; James R. Neilson
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：March 22, 2016
• 年：2016
• 卷：28
• 期：6
• 页码：1854-1860
• 全文大小：404K
• ISSN：1520-5002

文摘

Preparation of metastable solid-state materials is often hindered by the limitations of traditional solid-state chemistry, namely the high temperatures required to induce solid-state diffusion. Here, we present the formation of the metastable pyrite polymorph of CuSe₂ through a metathesis reaction mediated by the Lewis base, triphenylphosphine (Ph₃P). The Ph₃P added to the double salt-exchange reaction CuCl₂ + Na₂Se₂ abstracts selenium from the precursor and promotes the reaction at 130–150 °C, rather than 300 °C required for the neat reaction mixture. Powder X-ray diffraction experiments indicate that substoichiometric amounts of added phosphine yield pyrite CuSe₂; infrared and nuclear magnetic resonance spectroscopies as well as mass spectrometry corroborate the formation of Ph₃PSe and Cu(Ph₃P)_{class="stack">n}^{class="stack">+} adducts, which implicates the Lewis base in facilitating atom-transfer reactions, thus lowering the activation barrier to forming the metastable pyrite polymorph of CuSe₂. These results provide an example of a new chemical approach for materials synthesis that will enable the synthesis of new, metastable crystalline materials.