Jewish Encyclopedia Volume 9 p419 states:

OPPENHEIMER, SAMUEL: German banker, imperial court factor, and diplomat; born at Heidelberg about 1685; died at Vienna May 3, 1703. He enjoyed the especial favor of Emperor Leopold I., to whom he advanced considerable sums of money for the Turkish war. Prince Eugene of Savoy brought him a large number of valuable Hebrew manuscripts from Turkey, which became the nucleus of the famous David Oppenheimer Library, now comprised in the Bodleian Library at Oxford.

He was appointed "Oberfaktor" and court Jew at the recommendation of Margrave Ludwig of Baden, the imperial general in Hungary, to whom he had advanced 100,000 gulden for war expenses.