non-bonded        
adjective [ before noun ]  chemistry specialized (also nonbonded) uk/ˌnɒnˈbɒn.dɪd/ us/ˌnɑːnˈbɑːn.dɪd/
 非结合的
not involving or held together by bonds (= strong forces)
  Non-bonded copper ions are toxic. 非结合的铜离子是有毒的。 
 The oxygen atoms have pairs of nonbonded electrons.
 - More examples
 - The interaction is stronger than a non-bonded interaction.
 - The energy of these molecules is far below that of a non-bonded molecule.
 - The non-bonded interactions contribute to the stability of the structure.
 - The parts are connected by weakly bonded or non-bonded interactions.
 - The nonbonded energy between large particles may be appreciable.