Ab Dominant 13th, 2nd inversion (D# in the bass)
Notes, from the bass up
D# (bass)F#A#C#E#G#B#
The same notes as Ab Dominant 13th (D#, F#, A#, C#, E#, G# and B#), rearranged so D# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.