Businessman Lochlann Quinn is understood to have bought one of the five paintings which were about to auctioned earlier this summer by the Beit Foundation.
Mr Quinn is believed to have spent about €2m acquiring a painting by the 17th century Flemish artist, David Tenier the Younger.
It is understood Mr Quinn (pictured) will donate the painting to the National Gallery where he is chairman.
The Beit Foundation had planned to sell the five paintings to help create a €10m endowment fund to provide ongoing financial support for Russborough.
The paintings were withdrawn from sale following controversy about their loss to the nation.