Do the children have the right to take a share of their father's inheritance based on his promise to them to do so before his death?

What your father offered you is considered a gift, and it is not executed except by the donee taking possession of it. If possession was not taken before the death of the giver, then it becomes part of his estate. Accordingly, you have no right to this gift since you did not take possession of it before your father's death, and it is considered part of his estate from which you are only entitled to your legal share.