9063
The electronic structure of the Fe - O ( 2 ) center in oxy - hemoglobin and oxy - myoglobin is a long - standing issue in the field of bioinorganic chemistry .
 Chemical: Fe; Chemical: O ( 2 )
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: Fe, O ( 2 ) 
Answer:
 Chemical: Fe; Chemical: O ( 2 )