This question assumes that there is complex, intelligent life on some other world other than the kind found on Earth.
Carl Sagan allowed that silicon and germanium might replace carbon, and ammonia is thought to be the next thing that could be a conceivable replacement to water as a solvent.
From wiki - Astrobiologist John Baross chaired a committee of scientists under the United States National Research Council that published a report on life's limiting conditions in 2007. The report addresses the concern that a space agency might conduct a well-resourced search for life on other worlds "and then fail to recognize it if it is encountered".
I saw a science TV show that postulated that Silicon based life might present itself as a rock floating in space (hand wave the possibility). Say we had a method that we could use to recognize that floating space rock as a living being, how would we then interact share complex abstract concepts with it?
Could life based on these other biochemistries interact with humans or would we be poisonous to one another? Could we share sciences? Would we even recognize one another? Or are the things that make us "alive" so different that we couldn't even interact?
This question is probably too broad as written but I thought I'd roll the dice.
EDIT: maybe the question suggests that I'm getting hung up on the "intelligence" part of the scenario. But actually not so much. No matter where we go in the universe the laws of physics will always be the laws of physics, 2 + 2 will always = 4, green will still be green no matter what we name it. On that basis alone we would have some way to start a dialog with another species no matter how alien.
But what if that alien is ammonia based? Wouldn't its body literally be poisonous to us? What if there was an alien that was made of energy? What if there was an alien whose physicality was such that we couldn't even detect it with any of our five senses (a concept I'm toying with now)?