Low‐Barrier Hydrogen Bonds in Negative Thermal Expansion Material H 3 [Co(CN) 6 ]
Abstract The covalent nature of the low‐barrier N−H−N hydrogen bonds in the negative thermal expansion material H 3 [Co(CN) 6 ] has been established by using a combination of X‐ray and neutron diffraction electron density analysis and theoretical calculations. This finding explains why negative ther...
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Published in | Chemistry : a European journal Vol. 25; no. 27; pp. 6814 - 6822 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
10.05.2019
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Subjects | |
Online Access | Get full text |
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Summary: | Abstract The covalent nature of the low‐barrier N−H−N hydrogen bonds in the negative thermal expansion material H 3 [Co(CN) 6 ] has been established by using a combination of X‐ray and neutron diffraction electron density analysis and theoretical calculations. This finding explains why negative thermal expansion can occur in a material not commonly considered to be built from rigid linkers. The pertinent hydrogen atom is located symmetrically between two nitrogen atoms in a double‐well potential with hydrogen above the barrier for proton transfer, thus forming a low‐barrier hydrogen bond. Hydrogen is covalently bonded to the two nitrogen atoms, which is the first experimentally confirmed covalent hydrogen bond in a network structure. Source function calculations established that the present N−H−N hydrogen bond follows the trends observed for negatively charge‐assisted hydrogen bonds and low‐barrier hydrogen bonds previously established for O−H−O hydrogen bonds. The bonding between the cobalt and cyanide ligands was found to be a typical donor–acceptor bond involving a high‐field ligand and a transition metal in a low‐spin configuration. |
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ISSN: | 0947-6539 1521-3765 |
DOI: | 10.1002/chem.201900358 |