12409
A variable difference in mid - point potential , in contrast , was observed for ferrocene and cobaltocenium relative to that of DmFc in similar ionic liquids .
 ferrocene, cobaltocenium, DmFc
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ferrocene, cobaltocenium, DmFc