Is a divorce enacted and an expiatory oath (kaffarat yamin) required of the husband who swore to divorce, intending to threaten, if his wife did not close her Facebook account, and she did indeed close it, then she reopened it for only one minute and then closed it again?

The preponderant opinion is that the intention of the swearer is what is considered in an oath. So, if one intends by his oath to do or not to do something in a specific way, he does not break his oath by doing or not doing it in a different way.

Based on this, you have not broken your oath by what your wife did, because it appears that she did not violate your intention, and the account opening was not deliberate. It is narrated from Ibn Taymiyyah that whoever does the sworn-against action forgetfully or by mistake is not considered to have violated the oath of the swearer. Likewise, if one forgets the oath or believes that his action is not the one sworn against due to interpretation or error.

Her browsing the account for a short period before closing it is not considered a violation unless you intended to prevent her from accessing it in any way. In that case, you would break your oath and your divorce would occur, except according to the opinion of some scholars like Ibn Taymiyyah, where you would be required to pay an expiation for the oath and your divorce would not occur.