Assigning values to dictionary outputs

I have a dictionary:

 Dictionary buttonNumber = new Dictionary()
         {
             {1, button1}, {2, button2}, {3, button3},
             {4, button4}, {5, button5}, {6, button6}
         };

Then try to assign this prefab to button1, button2, button3.... via

 buttonNumber[numButtons] = Instantiate(newButton, new Vector3(0, 0, 0), newButton.transform.rotation);

newButton is a prefab of a button, which is defined in the script as type Button not Gameobject. When I try to access my Buttons via Debug.Log (button1) they all come back null.

What am I missing? / Is there a better way to do this (referencing the prefab instances)? Thanks