What goes before this, the V/V of C?
As Submedient 1st inv (vi6) chord, with optional passing note
(Solution group 1: C)
As Tonic (I) chord, with optional passing note
(Solution group 1a: B#) this is a chromatic As Leading note crazy inv (viid9) 9th chord, possibility; note this is actually E sharp pretty insane sound (this is out of conext and minor 9th! Like who is insane enough to do practice; note the Rootx2, third and seventh that, really. Perhaps as a Secondary chords (Solution group 2: C#) configuation of the V7/V!) ...vii of F#-?
If you sharp the A to A# you get something out of context again; they are probably shown as passing-note in a V6 (or 6/5 if its a 7th chord of V)Yet it sounds smooth enough nonetheless
...With historic roots to renaissance crap Usually before all this chromatic crap Classic V of V of V, first inversion, with its much more common to see a V of ii like this, of some sort. Notice the S/A second last chord is not P5 but dim5 so its not P5ths passing note at Alto leading to the V7 instead of a V of V of V... with the last chord of V of V (optional)
As Supertonic 3rd inv (ii4/2) 7th chord, pretty insane sound (C should be C#, but that's another topic; C# as the V of V of V)
As Subdominant 2nd inv (IV6/4) chord, not exactly the best choice (very rare)
Is this even possible? F# third inv chord Another chromaticisms almost 20th C. which the Fifth goes up by semitone, Perhaps late romantic, by common tones doesn't sound too right, perhaps voicing D flat = C # is crapped up.