Not exactly. They have overlapping meanings. Coerce means to force another to act or think a certain way, while wheedle means to persuade another, by compliments or flattery, to act act or think a certain way.
The opposite (antonym) of antonym is synonym. An antonym is a word that means the opposite. A synonym is a word that means the same thing, or nearly the same thing, for a given context.
Some words do not have direct opposites [antonyms]. Antonyms do not usually substitute for phrases. The phrase "you are" has no antonym. A contrasting version of "you are" is "you are not".