C# Minor Major 9th, 4th inversion (D# in the bass)
Also written as C#m(maj9)/D#.
Notes, from the bass up
D# (bass)C#EG#B#
The same notes as C# Minor Major 9th (D#, C#, E, G# and B#), rearranged so D# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.