Dear J.,
You are right, your attention is not the problem. The problem is he is 18 months old and that is what THEY do. They will also clean out the dryer, the dirty close basket, clean off the coffee table, the kitchen cupboards and then righteously walk or crawl away, happy that they could be of help.
When he starts throwing, go over there and tell him where to PUT the toys and then help him calm down. He will get it. The talking is just not what he needs at this point, unless it is companionable talking while the two of you PUT the toys instead of throw. Maybe just leave 3 or 4 toys in the basket. Change them each day, and he will become more interested in them as toys instead of flying missles.
Good Luck, aren't 18 month olds just the cutest people on this earth ? C. N.