These first two sentences show никто split with a preposition:
Я ни у кого не был. (I haven’t visited anybody.)
Он ни с кем не говорит. (He’s not speaking to anybody.)
Applying this pattern I came up with the following sentences:
Я не обсуждал это ни с кем. (I haven’t discussed this with anybody.)
Я бы никогда не сказал такую вещь ни о ком. (I would never say such a thing about anybody.)
Are these last two correct? Also would ни о ком be pronounced with a long o for both о and ком? Thanks!