Cooper Union sent RFR, the ground lease holder, a 10-day termination notice after the firm missed payments in June and July.

Elsewhere in the city, lenders and city agencies have sued RFR for missed loan and tax payments at 17 State St., 522 Fifth Ave. and 90 Fifth Ave. The jewel in Rosen’s crown, the Seagram Building, carries nearly $1 billion in mortgage and mezzanine debt that must be refinanced next year. RFR controls nearly 3 million square feet of commercial space.

The owner of the land beneath the historic Chrysler Building said Friday it was taking control of the office tower, in what would be one of the most prominent buildings in the U.S. to be lost during the office-market collapse.