[noneed2live]

in the image I've attached, why is it that there is only one stereocenter/chiral center (indicated by the asteriks)? Why can't the HN at the bottom left of the diagram also be chiral? In regards to the bonds connected to that HN, it appears to me that the carbons on both sides of this Nitrogen are different in that stuff towards the left side of th left carbon is different from stuff towards the right side of the right carbon

[Arkcon]

Your question, despite several differences in the molecules, is essentially the same as the one in this thread: http://www.chemicalforums.com/index.php?topic=86583.0

[noneed2live]

Your question, despite several differences in the molecules, is essentially the same as the one in this thread: http://www.chemicalforums.com/index.php?topic=86583.0

Thank you!

[lb2]

Hi noneed2live,

Your question is in fact very different from the question in the other thread. Arkcon might have been thinking about something else.

In any case, as you mention there are indeed four different units attached to the nitrogen atom you mentioned. But before you go any further, you need to consider the hybridization and geometry of this nitrogen atom. Is this nitrogen atom tetrahedral?

Hope this helps!

(P.S. By the way, you need to be wary of nitrogen atoms when looking at stereocenters. Although this consideration may not apply to your specific compound, always remember that most tetrahedral nitrogen atoms with three groups and a lone pair invert very rapidly. If the three groups attached to this tetrahedral nitrogen are different, then the nitrogen atom is indeed a stereocenter, and the two tetrahedral structures related through inversion at the nitrogen center are enantiomers. However, since the nitrogen inversion is very rapid, it will usually not be possible to isolate only one of the enantiomers.)