A sprawling duplex co-op on prim Park Avenue that had been owned by Hassan Nemazee, who apparently lived a tad too large before being sentenced in 2010 to 12 years in prison for $292 million in bank fraud, was sold by the federal government for $17.75 million, the most expensive sale of the week, according to city records. Mr. Nemazee, the chairman of Nemazee Capital, was a prominent donor to the Democratic Party and a national finance chairman of Hillary Rodham Clinton's 2008 presidential campaign. His ample assets, including the terraced 15-room apartment, No. 14/15A at 770 Park, a 2008 Maserati and residential property in Katonah, N.Y., and TriBeCa, were seized by the government to repay his debts; the co-op was originally listed at $28 million in 2011 but attracted no takers. After several reductions, its most recent asking price was $19.5 million. The lower floor of the apartment at the Georgian-style 1930 Rosario Candela-designed building at 73rd Street has a 29-foot corner living room and a 20-foot library, both with wood-burning fireplaces and Park Avenue frontage. The windowed kitchen has a breakfast area, a staff hall and a butler's pantry. The original herringbone floors have been retained throughout the unit. The upper level has six bedrooms, each with an en-suite bathroom; there are two terraces, one facing east off the master bedroom, a staff suite and a laundry room. John Burger and Nancy J. Elias of Brown Harris Stevens were the listing brokers on behalf of the United States government. The buyers are Thomas Purcell, an analyst with Viking Global Investors, and his wife, Marina Shields Purcell, a half-sister of the actress Brooke Shields. A confidentiality agreement prevented the brokers from commenting on the sale.