An unusual duplex co-op at 88 Central Park West, reconfigured in 2007 to capture treetop and cityscape vistas to the north and west, sold for $19.5 million and was the biggest sale of the week, according to city records. Located in the Brentmore - an address whose residents past and present have included Robert De Niro, Sting, Laurie Tisch, Celeste Holm, and, almost, Matthew Broderick and Sarah Jessica Parker - the fully renovated 6,000-square-foot apartment offers five bedrooms, five and a half bathrooms and staff quarters, and is accompanied by a formidable $11,205 monthly maintenance fee. The light-filled living spaces are concentrated on the eighth floor, with the bedrooms and a 30-by-20-foot family room on the ninth. Oversized windows distinguish both floors. 8N9W, was created after N. J. Nicholas Jr., a former chief executive of Time Warner, combined his eighth- and ninth-floor north-facing duplex with No. 9W, an apartment previously owned by Kirk Henckels, a broker at Stribling & Associates, and his wife, the socialite Fernanda Kellogg. Mr. Henckels was the listing broker in the current sale as well; the duplex, with a $22 million asking price, was on the market for three months. Mr. Nicholas, now a director of the Boston Scientific Corporation, and his wife, Llewellyn, moved farther west, to Riverside Drive. The sale of the Henckels unit for its asking price of $4.6 million in 2007 resulted from a spirited bidding war between Mr. Nicholas and Mr. De Niro, who had acquired his own duplex on the fourth and fifth floors in 2006 for $20.9 million. Mr. Henckels said he and his wife decided to sell their apartment to the Nicholas family rather than Mr. De Niro for sentimental reasons. "The Nicholases are lovely people and had been lovely neighbors," he said, "and we knew they wanted to use our apartment to expand their home for their family." Mr. De Niro was apparently looking for more office space and a place for a personal gym, not living quarters. Hence the snub. With Mr. De Niro's duplex temporarily off-limits because of a fire last month traced to an overstuffed lint filter in the unit's dryer (presumably Mr. De Niro's chores do not include doing the laundry and thus he is not to blame), there had been speculation that he was on the prowl to acquire No. 8N9W, speculation further fueled by the recent sale for $9.5 million of a historic 1852 town house at 14 St. Luke's Place that he had owned for 30 years. But Mr. Henckels discounted the rumors of a De Niro takeover at the Brentmore, which was built in 1910. I can absolutely say with authority that the buyer is not De Niro. Mr. De Niro was sighted recently checking out a $75,000-a-month town house rental in Greenwich Village. The buyer of No. 8N9W remains a mystery, the identity shrouded by a limited-liability company, Revocable Trust. Mr. Henckels said he was not at liberty to disclose that information. The buyer's broker, Eileen Eck of the Fox Residential Group and Newmark Knight Frank, also declined to elaborate. She did say the buyers "are lovely people" who intend to use the place as a primary residence, and she, too, said the buyer "is not Bob De Niro, not even close."