Section 18.4 Writing Secondary Diminished Chords
To write a secondary diminished chord, use the following procedure.
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First determine the note that is the root of the chord being tonicized (the chord to the right of the slash).
- Determine \(\left.\text{vii}^{\circ}{}^{7}\right.\) in the key of C minor (C is the root of the \(\left.\text{iv}\right.\) chord, which is the Roman numeral after the slash): B is the root of \(\left.\text{vii}^{\circ}{}^{7}\right.\) in C minor because it is a m2 below C.
- Build a fully–diminished seventh chord on B: B–D–F–A♭
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Invert the chord accordingly. \(\left.\text{}^{4}_{2}\right.\) inversion means the 7th of the chord (A♭) is the bass note.
