"Preliminary" means something done in advance, in preparation, so this is a good use of the word. You could simplify the sentence a little, if you wish: "Our preliminary discussions have motivated me to look for an opportunity to talk further."

In this case, I would not use "preliminary," because the word "preliminary" means something done in preparation for a future event or situation. In this case, it seems that there isn't necessarily any preparation going on, so it doesn't make sense to use "preliminary." The speaker simply is motivated to talk to "him" again. Instead, you could say "previous," which simply means "before."

Just simply say, "Following our previous conversation, I would like to talk to him further." There is no need to go into all the superfluous "preliminary", "motivated" and "chance".