6600
A strong dependence of the dehydrogenation temperature and purity of the released hydrogen upon heating on the coordination number of NH ( 3 ) was elaborated for Mg ( BH ( 4 ) ) ( 2 ) . xNH ( 3 ) owing to the change in the molar ratio of H ( delta + ) and H ( delta - ) , the charge distribution on H ( delta + ) and H ( delta - ) , and the strength of the coordinate bond N : --> Mg ( 2 + ) .
 hydrogen, NH ( 3 ), Mg ( BH ( 4 ) ) ( 2 ) . xNH ( 3 ), H ( delta + ), H ( delta - ), H ( delta + ), H ( delta - ), N : --> Mg ( 2 + )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 hydrogen, NH ( 3 ), Mg ( BH ( 4 ) ) ( 2 ) . xNH ( 3 ), H ( delta + ), H ( delta - ), H ( delta + ), H ( delta - ), N : --> Mg ( 2 + )