I came across a question that asked the correct structure of trichloroborazine. The two options provided were : a) the chlorine atoms attached to the three N atoms, and b) the chlorine atoms attached to the 3 B atoms

My idea was that, since, in borazine, the N atoms have a formal +1 charge, the Cl would more readily bond to it, making (a) the correct answer. But, turns out, it's actually (b) that's the correct structure. Why is it so, and what is wrong with my reasoning? Edit: If both (and other) structures are at least theoretically possible, then which one is the most stable and/or most common one, and why so?

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    $\begingroup$ The big issue I see in your reasoning is that formal charge is a formality, not a real charge. Don't use it where real charges matter. $\endgroup$ – Zhe May 9 '18 at 15:54
  • $\begingroup$ @zhe I get that, yes, and I only employed that line of reasoning because I couldn't think of any other. It was a case of "better this than nothing". I'd love to know the actual/correct logic... $\endgroup$ – Navy May 9 '18 at 16:01
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    $\begingroup$ I'm going to put it out there that your question, as phrased, doesn't make sense. If the question was "what is the correct structure of water", then fine, H–O–H is the correct structure. However, the name "trichloroborazine" is ambiguous and can refer to either of the two structures you have chosen, or potentially even more as there is no stipulation as to where the chlorines are attached to. So, there is no single correct structure corresponding to the name "trichloroborazine". $\endgroup$ – orthocresol May 9 '18 at 22:08
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    $\begingroup$ Granted, (b) is probably a more stable isomer than (a), or any of the other possible isomers. But then you need to rephrase the question appropriately. $\endgroup$ – orthocresol May 9 '18 at 22:12
  • $\begingroup$ @orthocresol I understand that there are other possible structures; however, the question was given as I have asked it. Also, a quick Google search for trichloroborazine does provide results only for 2,4,6 trichloroborazine (with cl attached to B atoms). So, are there any reasons for this structure being the most common/stable one? $\endgroup$ – Navy May 10 '18 at 1:08

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