- Neither you nor he is right.
- Not either you or he is right.
- Either you or he is not right.
- Both you and he are not right.
Examples 1, 3, and 4 are grammatical; example 2 is not. ("Not either" = "Neither")
Examples 1 and 4 both mean the same thing, i.e., that both individuals are wrong (although some may argue that the two statements have differing connotations or emphases).
Example 3 does not mean the same thing as 1 and 4, but instead posits that only one person is wrong instead of both.