[gleeman]

The general question was given by my teacher: "Which one of the following has different isomers: HNNH and H2NNH2?"

I found that HNNH has two isomers: the other is polar and the other non-polar (perhaps cis and transisomers).

The answer of my teacher was that H2NNH2 has no isomers but HNNH has.
On the other hand, in my opinion, H2NNH2 has isomers: NH3-NH, H2-N-N-H2.
Are those isomers or is my teacher right that H2NNH2 has no isomers?

Thank you in advance!

[AWK]

diimide (HN=NH) has isomer cis and trans

Try drawing complete Lewis structure for NH3-NH - and all will be clear, I do hope

[gleeman]

Try drawing complete Lewis structure for NH3-NH - and all will be clear, I do hope

Did I understand right that the reason NH3-NH has no geometric isomers is that it cannot be rotated?

Then again, NH3-NH and H2-N-N-H2 have still the same molecular formula (N2H4) but different structural formulas. Does this make them isomers?

Thank you for your reply!

[AWK]

Lewis structure can show NH3-NH is extremely unfavourable

[shelanachium]

It is possible to draw a structure for H3NNH, it would be polar H3N+---NH- (similar structures are found in amine oxides like (CH3)3N+---O-). But H3N+---NH- would be unstable, H+ would immediately transfer from the [NH3]+ group to the [NH]- group. The result, ordinary hydrazine H2N-NH2!

[gleeman]

Thank you for your responses!

Your answers solved the question.