BASH Scripting - Passing strings via SSH

BASH Scripting - Passing strings via SSH

I have a set of scripts that I use to download files via FTP and then delete them from the server.
It works as follows:
for dir in `ls /volume1/auto_downloads/sync-complete`
do
if [ "x$dir" != *"x"* ]
then
echo "DIR: $dir"

echo "Moving out of complete"
        # Soft delete from server so they don't get downloaded again
        ssh dan@172.19.1.15 mv -v "'/home/dan/Downloads/complete/$dir'" /home/dan/Downloads/downloaded
Now $dir could be "This is a file" which works fine. The problem I'm having is with special characters eg:
"This is (a) file"
This is a file & stuff"
tend to error: bash: -c: line 0: syntax error near unexpected token (' bash: -c: line 0:mv -v '/home/dan/Downloads/complete/This is (a) file' /home/dan/Downloads/downloaded'
I can't work out how to escape it so both the variable gets evaluated and the command gets escaped properly. I've tried various combinations of escape characters, literal quotes, normal quotes, etc