The George Mason University Foundation yesterday bought an 11-acre parcel of land strategically placed at a future Arlington Metro station, and said it plans to develop "a major metropolitan educational-commercial center" there.

The center would include not only classrooms and possibly a law school for George Mason, but a variety of office and other commercial space that would help finance the university's goal of becoming a major educational force in Northern Virginia.

"It will be a fabulous arrangement," said foundation trustee John T. Hazel Jr., a zoning attorney who has been a major figure in many large development deals in Fairfax County.

"Arlington County is dying to get class development along the Metro corridor." Hazel said.

The future subway station is Virginia Square, along a Metro line scheduled to open in December 1979. It is adjacent to the proposed new campus, which is bounded by Fairfax Drive, Washington Boulevard, Kirkwood Road and Monroe Street.

The foundation announced no timetable for its building plans, but said classes would initially be held in the old Kann's department store, which was part of the sale.

George Mason president George Johnson said the property, purchased by the foundation for about $3.5 million, "gives the university a window in Arlington that's almost beyond compare . . . It's a major step in George Mason becoming a truly comprehensive regional university,"

Though George Mason has 10,767 students and is the state university for Northern Viginia, its growth has not kept pace with demand in the region it serves, foundation and university officials said.

According to Hazel, 60 out-of-state institutions - some as eminent as the University of Southern California and some so shadowy that they are difficult to trace - have come to Northern Virginia offering courses and even doctoral programs that are not available at George Mason or the nearby extensions of other state colleges.

"They (out-of-state schools) come here where the profit center is, make a buck, but don't provide quality service - that's no way to do it," Hazel said.

Johnson said "all higher education has to worry about some of the shlock being offered." To meet some of the demand that is attracting other schools, Johnson said George Mason is seeking to expand its doctoral programs and add courses in economics and business.

But George Mason's number one priority - the sought'after Keystone for the educational-commercial center it wants to create at Virginia Square - is winning affiliation for the 600-student International School of Law, which sold the 11-acre parcel to the foundation.

While affiliation would give George Mason some educational prestige and power it now lacks, some university supporters complain that downstate forces - fearful of a syphoning effect on the University of Virginia and other state institutions with law schools - are trying to prevent that from happening.

Earlier this month, the State Council of Higher Education turned down affiliation on the ground that the state could not afford the additional financial aid to George Mason that would be required. Three attempts to win law school affiliation through the General Assembly also have failed.

But foundation and university officials think that purchase of the Virginia Square property, with a functioning (though unaccredited) law school and the potential for commercial space helping to subsidize the school improves the prospect of favorable action by the General Assembly at its next session, which begins in January.

George Mason's main campus is just south of Fairfax City, distant from most of its potential student population and in an area poorly served by public transportation, Hazel said the Virginia Square campus would put the university within far easier reach or its "vast clientele."