( ( As ( a ligand ) ) ( , ( porphyrin ( ( ( forms ( numerous complexes ) ) ( with ( ( metallic ions ) ( like ( ( iron ( in hemoglobin ) ) ( ( that colors ) ( blood red ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (DT a) (NN ligand))) (, ,) (NP (NN porphyrin)) (VP (VBZ forms) (NP (JJ numerous) (NNS complexes)) (PP (IN with) (NP (NP (JJ metallic) (NNS ions)) (PP (IN like) (NP (NP (NN iron)) (PP (IN in) (NP (NN hemoglobin))) (SBAR (WHNP (WDT that) (NNS colors)) (S (NP (NN blood)) (ADJP (JJ red))))))))) (. .)))
As a ligand, porphyrin forms numerous complexes with metallic ions like iron in hemoglobin that colors blood red.
(ROOT (S (NP (NNP Iron) (NNS ions)) (VP (VBP are) (ADJP (JJ critical) (PP (IN for) (NP (NP (DT the) (NN formation)) (PP (IN of) (NP (NN hemoglobin))))))) (. .)))