Chords in the key of E flat major
The chart below lists the common chords in the key of E 
flat major. The first row are triads and four note 
voicings are in the second row. Roman numerals indicate 
each chords position relative to the scale.

E flat major scale notes: Eb F G Ab Bb C D
Major key chord sequence: Maj min min Maj Maj min dim
D sharp major
The same chords and scale notes are used for the key of D 
sharp major but this key isn't used often because of 
notation difficulties caused by the need for a double 
sharp. More info on this can be found here in chord theory.

I	ii	iii	IV	V	vi	vii
Ebmaj	Fmin	Gmin	Abmaj	Bbmaj	Cmin	Ddim
Ebmaj7	Fmin7	Gmin7	Abmaj7	Bb7	Cmin7	Dm7b5
Common chord progressions in E flat major
I - IV - V	Eb - Ab - Bb
I - vi - IV - V	Eb - Cm - Ab - Bb
ii - V - I	Fm7 - Bb7 - Ebmaj7