National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 22	May 2022
NIST Standard Reference Database 101

I	Introduction
II	Experimental data
III	Calculated data
IV	Data comparisons
V	Cost comparisons
VI	Input and output files
VII	Tutorials and Units
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IX	Feedback
X	Older CCCBDB versions
XII	Geometries
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XIV	Reaction data
XV	Entropy data
XVI	Bibliographic data
XVII	Ion data
XVIII	Bad calculations
XIX	Index of properties
XX	H-bond dimers
XXI	Oddities

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XXI.A.

NaCN is not linear

Assuming similarity to H-C≡N (hydrogen cyanide), which is linear, it is reasonable to assume gas-phase Na-C≡N would be linear too. An isomer of H-C≡N exists, C≡N-H (hydrogen isocyanide, also linear) which is approximately 62 kJ mol^-1 higher in energy. For Na-C≡N there is a very marginally stable structure for the C≡N-Na geometry. It is close to the same energy (within 10 kJ mol^-1) of the Na-C≡N geometry. However the lowest energy (most stable) geometry is triangular with the Na almost perpendicular to the C≡N bond.