Okay kiddo, do you know what metal is? It's like the shiny stuff that things like cars and jewelry are made of. And do you know what a complex is? It's when a bunch of things join together to make something new.
So, a metal nitrido complex is when a metal joins together with a tiny chemical called nitride. The metal and nitride become buddies and stick together. They're so close that they form a new molecule, which we call a complex.
Now, this metal nitrido complex is super special because of the way the metal and nitride are joined together. They're joined together in a really strong and stable way. This means that the metal nitrido complex is very useful for all sorts of things like making drugs and designing new materials.
And that's it in a nutshell, kiddo!