Left hand resonance form best represents polarity, right hand resonance form best represents bond length and strength (triple bond).

Sources of information

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  • J. Phys. Chem. A (2005) 109, 5129–5135: "Thermodynamic Properties of Molecular Borane Amines and the [BH4][NH4+] Salt for Chemical Hydrogen Storage Systems from ab Initio Electronic Structure Theory"