The missing works include Monet's Waterloo Bridge, Picasso's Tete d'Arlequin, Matisse's La Liseuse en Blanc et Jaune and Freud's Woman with Eyes Closed.
Italian-born Donati bought Arlequin in Paris in the 1940s after becoming entranced by an early Cubist work by Picasso during a visit to the Musee d'art moderne.