( in ( metallic bond ) )
(ROOT (PP (IN in) (NP (JJ metallic) (NN bond))))
in metallic bond
(ROOT (S (NP (JJ Metallic) (NNS bonds)) (VP (VBP hold) (PRT (RP together)) (NP (NP (JJ positive) (NN metal) (NNS ions)) (CC and) (NP (PRP$ their) (JJ valence) (NNS electrons)))) (. .)))