22.6: Modulations with Chromatic Pivot Chords
You will sometimes encounter examples where the pivot chord is a chromatic chord in at least one (and sometimes both) of the keys involved in the modulation.
22.6.1 Secondary Common Chord
Below is an example where the pivot chord is a secondary chord in both keys.
22.6.2 Borrowed Common Chord
In modulation by borrowed common chord (or mode mixture), the pivot chord will be a borrowed chord in one of the keys involved in the modulation. In the following example, a borrowed chord, ii6 in D♭ minor, rewritten as a C♯ minor chord, is reinterpreted as vivi6 in the second key, E major.
22.6.3 Neapolitan Common Chord
A particularly adventurous and imaginative pivot is the Neapolitan, which can bridge the gap between two foreign (or distantly related) keys.
In the example above, Schubert bridges the tonal distance between D minor and A♭ minor with NN56 (note the dominant-seventh quality of the Neapolitan in this instance), which acts as a VV56 in A♭ minor, a tritone away from D minor.
22.6.4 Augmented Sixth Common Chord
In the next chapter, we will examine how Augmented Sixth chords are enharmonically reinterpreted in a process known as enharmonic modulation.