Tenants of the Promenade apartments in north Bethesda are organizing in an attempt to buy their 1,072-unit complex, recently sold for $54 million to American Invsco.

American Invsco, a Chicago firm that is a major converter of rental apartments to condominium ownership and last year converted the nearby Grosveror Park complex, refuses to discuss the Promenade purchase. But sources said the firm is planning to convert the compartments to co-operative ownership, which would likely make it legally immune to Montgomery County laws governing conversions to condo ownership.

The county office of consumer affairs said this week that tenant rights to form an association to purchase a building sold for conversion apply only when condominiums are planned.

Officials said American Invesco has filed an affidavit stating it does not intend to convert the property to condominium ownership.If such an affidavit is filed, the law does not require that tenants be given 150 days to organize and purchase the building, consumer officials said.

To date, neither American Invsco nor the former owner, Nathan Landow, have notified the tenants of any pending sale or of any conversion plans.

A spokesman for the tenants said that a law firm, has been retained to represent the residents, some of whom have made improvements to their rental units on the understanding that they would be living there "for the rest of their lives." Some Promenade residents moved there five years ago from the Colonnade in the District, which Landow and others sold to condominium converters.