7959
Conversely , ' 2 + 1 + 1 ' complexes exhibit increased propensity to dissociation as shown by ESI - MS measurements and X - ray structure determination at low temperature ( 150 K ) of the polymeric complex { [ H ( 2 ) B ( tz ( NO2 ) ) ( 2 ) ] Cu [ PCN ] } ( n ) 6b .
 Chemical: { [ H ( 2 ) B ( tz ( NO2 ) ) ( 2 ) ] Cu [ PCN ] } ( n )
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: { [ H ( 2 ) B ( tz ( NO2 ) ) ( 2 ) ] Cu [ PCN ] } ( n )