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The coordination of methane , the first step in methane activation , to coordinately unsaturated first row transition metal dication complexes has been studied computationally to determine the most stable metal - methane interaction .
 Chemical: methane; Chemical: methane; Chemical: transition metal dication complexes; Chemical: methane
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: methane; Chemical: methane; Chemical: transition metal dication complexes; Chemical: methane