The £5m deal for Boateng will bring Boro's summer spending spree to over £20m, still with the possibility of adding Jesper Blomqvist to the squad, although he will not cost Boro a penny after being released by Everton at the end of last season.
Boateng will become just the second Dutch born player to play for Boro, following in the footsteps of Heine Otto who played for Boro in the 1980's for four seasons.