Mr. Socol said the current plan was to sell the office condominium to a conventional commercial developer.

So Mr. Trump filed plans with the state attorney general to turn the building into an office condominium.

"We approached the owners and asked them if they would sell us the space" as an office condominium, he said.

Philips is asking about $675 a square foot for the office condominiums.

Both have floor areas at the high end of the range typical in office condominiums in the city, which are about 5,000 to 25,000 square feet.

Several office condominiums being developed in Harlem may provide an alternative.

As the number of office condominiums increases nationwide, so does knowledge about how to run them.

Roughly 15,000 square feet of space dedicated to office condominiums is being envisioned for professionals like doctors and lawyers.

The scarcity of office condominiums works against their success in two ways.

To accommodate the art center's desire to own the facility, the building is being converted into an office condominium.