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Is this molecule on the left chiral or achiral?

1,4‐dibromo‐octahydropentalene

I believe it is achiral because its mirror image (on the right) is essentially the same molecule. But I was told that it is chiral because it doesn't have an internal plane of symmetry. Could someone tell me which explanation is correct?

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It indeed is achiral, because the red dot is the center of symmetry, hence it is superimposible with its mirror image. Having an internal plane of symmetry is not the only criterion, the presence of a centre of symmetry also leads to the compound being achiral.

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    $\begingroup$ If you rotate the mirror image on the right 180 degrees about the axis shown by the blue line, you arrive at the original molecule in the original orientation shown on the left. $\endgroup$ – Karsten Theis Dec 14 '20 at 2:23
  • $\begingroup$ Yeah thats why i said it is achiral. $\endgroup$ – Aditya Mishra Dec 14 '20 at 2:25
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    $\begingroup$ Yes, but the OP did not only ask for the answer but also wanted to know which explanation is correct. $\endgroup$ – Karsten Theis Dec 14 '20 at 2:29

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