Synthesis, decomposition studies and crystal structure of a three-dimensional CuCN network structure with protonated N-methylethanolamine as the guest cation.

Christopher Koenigsmann,Christina M Sheedy,Peter W R Corfield,Leena N Rachid

doi:10.1107/s2053229620004477

Christopher Koenigsmann, Christina M Sheedy + Show 2 more

Open Access

https://doi.org/10.1107/s2053229620004477

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Abstract

The compound poly[2-hydroxy-N-methylethan-1-aminium [μ3-cyanido-κ3C:C:N-di-μ-cyanido-κ4C:N-dicuprate(I)]], {(C3H10NO)[Cu2(CN)3]}n or [meoenH]Cu2(CN)3, crystallizes in the tetragonal space group P43. The structure consists of a three-dimensional (3D) anionic CuICN network with noncoordinated protonated N-methylethanolamine cations providing charge neutrality. Pairs of cuprophilic Cu atoms are bridged by the C atoms of μ3-cyanide ligands, which link these units into a 43 spiral along the c axis. The spirals are linked together into a 3D anionic network by the two other cyanide groups. The cationic moieties are linked into their own 43 spiral via N-H...O and O-H...O hydrogen bonds, and the cations interact with the 3D network via an unusual pair of N-H...N hydrogen bonds to one of the μ2-cyanide groups. Thermogravimetric analysis indicates an initial loss of the base cation and one cyanide as HCN at temperatures in the range 130-250 °C to form CuCN. We show how loss of a specific cyanide group from the 3D CuCN structure could form the linear CuCN structure. Further heating leaves a residue of elemental copper, isolated as the oxide.

Highlights

Copper cyanide networks have been studied extensively in light of their interesting and unpredictable topologies, their photoluminescence, and the possible applications of their physical properties
Our program of structural studies on mixed-valence copper cyanide complexes has sought to prepare neutral CuCN networks by incorporating divalent copper ions into CuI networks, the CuII atoms being stabilized by coordination to one or more chelating ligands in the form of nitrogen bases
We have been unable so far to prepare a crystalline mixed-valence copper cyanide compound involving this base, we developed modified procedures to synthesize pure compound (I) in light of its interesting structural properties

Summary

Introduction

Copper cyanide networks have been studied extensively in light of their interesting and unpredictable topologies, their photoluminescence, and the possible applications of their physical properties (see, for example: Grifasi et al, 2016; Pike 2012; Dembo et al, 2010; Tronic et al, 2007). Our program of structural studies on mixed-valence copper cyanide complexes has sought to prepare neutral CuCN networks by incorporating divalent copper ions into CuI networks, the CuII atoms being stabilized by coordination to one or more chelating ligands in the form of nitrogen bases. The synthesis and structural analysis of the title compound, poly[2hydroxy-N-methylethan-1-aminium [3-cyanido-3C:C:N-di-cyanido-4C:N-dicuprate(I)]], (I), arose from an initial attempt to prepare such a neutral mixed-valence complex by partial reduction of Cu2+(aq) with the cyanide ion in the presence of N-methylethanolamine (meoen) as the stabilizing chelating ligand, a method which has previously produced crystalline products when chelating diamines were used (see, for example: Corfield & Sabatino, 2017). We have been unable so far to prepare a crystalline mixed-valence copper cyanide compound involving this base, we developed modified procedures to synthesize pure compound (I) in light of its interesting structural properties. Our laboratory is carrying out similar studies on a number of other CuCN networks based upon N-alkylethanolamines

Experimental

Refinement

Description of the structure

Thermal decomposition studies