I was thinking about an organic chemistry problem a few days ago but reached a dead end. There were 2 parts to this question.
The first was thinking about the isomers of 'C3H4X2' [where X could be anything like a halogen or a deuterium etc].
I came up with the following 7 isomers:
(I've really tried to make it as clear as possible! Hopefully it has worked!)
...but a website I found stated that there were only 4:
;with their 'D' representing a deuterium.
So this is the first aspect of my quandary - what am I doing wrong when I draw these isomers!
The second aspect to this question was about considering the symmetry of these organic molecules. In particular, considering firstly 'plane symmetry' [which I understand] and 'rotational symmetry' [which I thought I understand but clearly I don't!]
The same website says that molecule A (from above) plane symmetry and rotational symmetry, which is fine.
But it also says that molecule C has plane symmetry but not rotational. Why is this? Surely if I rotate this molecule 60 degrees I get the same shape?
And then finally, they say that molecules B and D have rotational symmetry but not plane symmetry which I think I understand but would appreciate any further comments if anyone had them.
Ultimately, I would be very grateful if someone could point me towards something which could help me understand rotational symmetry in organic molecules and in particular why these examples given above have their particular symmetries! Thank you very much, everyone!