Secondary Leading Tone Chords
Secondary leading tone chords occur when diminished triads and seventh chords are used to tonicize a note/chord other than the given key’s tonic note/chord. The same principles apply to secondary leading tone chords as to secondary dominant chords, which is to say that any note/chord that can be tonicized by a V(7) can be tonicized by a viio(7).
The most used secondary leading tone chords in major and minor keys are the viio and the viio7. The viiØ7 is used less often but is occasionally seen tonicizing major chords, for example viiØ7/IV. The purpose of secondary leading tone chords is the same as secondary dominants, and together these chords provide the composer with a greatly enhanced harmonic palette. As with secondary dominants, secondary leading tone chords are substitutes for more common diatonic chords within the chart of harmonic progression. Additionally, secondary leading tone chords often pass through a cadential six-four on the way to the dominant chord. In the following example, the viio7/V is clearly substituting for the subdominant IV chord.
Spelling and Identifying Secondary Leading Tone Chords
Because you now understand the construction and function of secondary dominant chords, learning to spell and recognize secondary leading tone chords is easy. If you want to spell a secondary leading tone chord, follow these simple steps.
- Find the note that is the root of the chord that will be tonicized.
- Go down a m2 to find the root of the secondary leading tone chord.
- Build a diminished triad, fully diminished seventh chord, or half-diminished seventh chord on that root.
For example, write the viio/V in e minor.
When you find a chromatic chord within a passage of music and think that it might be a secondary leading tone chord, use the following steps to analyze the chord.
- Check to see if the chord is a diminished triad, fully diminished seventh chord, or half-diminished seventh chord. If it is not, then the chord is not a secondary leading tone chord. If it is a diminished triad, fully diminished seventh chord, or half-diminished seventh chord, go to step #2.
- Find the note that is a m2 above the root of the chord. If that note is the root of a diatonic major or minor chord within the key, then the chord is a secondary leading tone chord.
For example, the following chord is a fully diminished seventh chord that tonicizes the mediant triad.
The part-writing procedures for secondary leading tone chords are essentially the same as for regular leading tone and leading tone seventh chords, and those rules should be reviewed.