Mutu and Donadel depart Fiorentina
Former Chelsea striker Mutu fell out with Fiorentina bosses last season after being questioned over a bar brawl and then walking out on training when an original January move to Cesena was blocked.
He has eventually got his way and moves on a two-year contract to the north-eastern Italian club, who surprisingly stayed up last term.
Napoli, in the Champions League proper next season, have boosted their ranks by bringing in the dependable if unspectacular Donadel after a move for Udinese's Gokhan Inler slowed.
The Naples side are also interested in Genoa left-back Domenico Criscito but have said they do not want to be drawn into a bidding war with managerless admirers Inter Milan.
Fiorentina now face a spot of rebuilding but coach Sinisa Mihajlovic, who has said Inter have spoken to him about their vacancy, has again vowed to stay in Florence.