You can get the requested functionality using wmctrl. For example, the following command moves the active window to position X:400, Y:300, and resizes it to 800x500 px.
wmctrl -r :ACTIVE: -e 0,400,300,800,500
To bind it to a key, just go to Settings > Keyboard > Shortcuts and create a custom shortcut with the command.
Check the man pages for more info ...