13087
Secondary interactions are demonstrated to direct the stability of well - defined Ru - NHC - based heterogeneous alkene metathesis catalysts .
 Chemical: Ru - NHC; Chemical: alkene
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: Ru - NHC; Chemical: alkene