2672
The corresponding results emphasize why the use of [ ( eta ( 7 ) - C ( 7 ) H ( 7 ) ) ZrCl ( tmeda ) ] is clearly an advancement in the chemistry of the still fairly unexplored area of cycloheptatrienyl transition metal complexes .
 Chemical: ( eta ( 7 ) - C ( 7 ) H ( 7 ) ) ZrCl ( tmeda ); Chemical: cycloheptatrienyl transition metal complexes
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: ( eta ( 7 ) - C ( 7 ) H ( 7 ) ) ZrCl ( tmeda ); Chemical: cycloheptatrienyl transition metal complexes