Frances L. Loeb, who spent a dozen years as New York City's liaison to its vast corps of foreign diplomats and a lifetime maintaining a family tradition of philanthropy, died on Friday at her home on Park Avenue. Mrs. Loeb, who also had homes in Purchase, N.Y., and Lyford Cay, Nassau, the Bahamas, was 89. With her husband, John L. Loeb, an investment banker, and other family members, Mrs. Loeb was a benefactor of Barnard College (where Adele Lehman Hall was named for her mother), of Central Park (the Loeb Boathouse and the Children's Zoo), Lewisohn Stadium (which bore her maternal grandfather's name), the Loeb Student Center at New York University and the Frances Lehman Loeb Art Center at Vassar. In 1990, the Loebs pledged $70.5 million to finance new faculty positions and scholarships to Harvard College. Mrs. Loeb was also a trustee of Vassar and Cornell University and an overseer of the New York Hospital-Cornell Medical Center. Frances Lehman Loeb was born in Manhattan on Sept. 25, 1906, into two of the German-Jewish families whose rise to prominence and zeal for public service were chronicled in Stephen Birmingham's 1972 book, "Our Crowd." These 100 or so families founded banking, securities and retailing empires and many were known for their philanthropies. Her mother was Adele Lewisohn, the daughter of Adolph Lewisohn, who made his fortune shipping mining products. Her father was Arthur Lehman of the investment banking family. One uncle, Herbert H. Lehman, became Governor of New York. Another uncle, Irving Lehman, became Chief Judge of the State Court of Appeals. Frances Lehman attended Vassar from 1924 to 1926. In 1926 she and John Loeb were married in the Park Avenue apartment of her grandfather Adolph Lewisohn. From the 1930's through the 1970's, Mr. Loeb was a partner in the investment firm of Loeb, Rhoades & Company. Besides her husband of 69 years, Mrs. Loeb is survived by their five children: Judith L. Chiara of Manhattan and Purchase, John L. Loeb Jr. of Manhattan and Purchase, Ann Loeb Bronfman of Washington, Arthur Lehman Loeb of Manhattan and Deborah Loeb Brice of London; 14 grandchildren, and more than 30 great-grandchildren.