Emerson String Quartet. (Lisa-Marie Mazzucco)

Renée Fleming will soon draw the curtain on her mainstream operatic career, as productions of “Der Rosenkavalier” at Covent Garden and the Metropolitan Opera next season will be the American soprano’s last. On Thursday night in the Kennedy Center Terrace Theater, Fleming teamed up with the Emerson String Quartet to reprise pieces by Austrian composers Alban Berg and Egon Wellesz they recently recorded for Decca.

A musicologist and composition student of Arnold Schoenberg, Wellesz composed his “Five Sonnets” for soprano and string quartet in 1934, before the Nazi annexation of Austria forced him to flee to England. Set to selections from Elizabeth Barrett Browning’s “Sonnets From the Portuguese,” these songs are strikingly dissonant and violent — as in the first sonnet’s image of Love seizing the poet by the hair — but they generally resolve to traditional harmonies. Fleming, who has excelled in similar works, such as Berg’s “Seven Early Songs,” was poised and rapturous, if occasionally covered by the amassed string sound. Violinist Eugene Drucker brought sweet-toned elegance to the first violin solos in the third and fifth songs.

The group recorded both versions of Berg’s “Lyric Suite” but performed it here with the part for soprano on a Baudelaire sonnet, revealing Berg’s love for Hanna Fuchs-Robettin, his friend’s wife. The dissonant harmonies, the results of Berg’s first experiment with serial procedures, are really only a step or two from the fevered chromaticism of Wagner, whose opera “Tristan und Isolde” is quoted in the last movement, given a sensual rendition by these performers.

The opening work, Brahms’s second string quartet, had significant intonation issues, especially from cellist Paul Watkins and first violinist Philip Setzer, renewing the impression that the group has not fully jelled since Watkins replaced David Finckel at cello. All memories of that low point, though, were forgotten by the encore, Erich Zeisl’s languorous song “Komm, heil’ge Nacht.”

Correction: A previous version of this review featured an outdated photo of the Emerson String Quartet featuringa former member.