A large office building is planned for a site half a block east of the new Metro station in mid-Bethesda.

The site is a one-acre tract at 4500 East-West Hwy., now a used car lot. It has been confirmed that Rozansky & Kay, a major development firm, has a contract to purchase the site for nearly $2 million from developer Nathan Landow.

Rozansky & Kay is planning a spring start on a 175,000-square-foot, eight story building with four levels of parking on the site. MOV, Inc., is designing the present concrete and bronze thermopane structure.

In addition to plans for the Bethesda Office Center, Rozansky & Kay also is developing other office buildings in Montgomery and Fairfax counties. The firm also has a contract to purchase the Rockefeller estate on Foxhall Road in the District as the site for a development of expensive single houses.

The site of the proposed Bethesda Office Center is just west of the East-West Towers office complex, where a third high-rise structure is being completed. That office triumverate will total 540,000 square feet. The general partners are John and Clarence Gosnell and A. James Clark and Benjamin Rome. The Gosnells are residential developers. Clark and Rome are top executives in the George Hyman Construction Co., the builder.

Meanwhile, developers Roger W. Eisinger and John K. Kilbane are planning a third "air rights" building on a site a few blocks south a 7315 Wisconsin Ave. The third building over the B&O railroad tracks is planning to have 360,000 square feet of space.