Secondary Leading Tones – Analysis

Definition: A secondary dominant is a dominant functioning chord of any major or minor chord in a key other than tonic.

After dissecting the definition of secondary dominants, we said that:

You can think of a secondary dominant as
an altered chord that follows the format
X/Y where

X = V, V7, vii^o, vii^ø7, vii^o7
Y = major or minor triad in the key other than I

We have already looked at a couple of examples where the top part of the secondary dominant, the X, is a dominant seventh chord. However, the X chord can also be a leading tone chord (a vii^o, vii^ø7, vii^o7); these types of secondary dominants are sometimes called Secondary Leading Tone Chords.

Let’s look at example of a secondary leading tone chord.

Rhythm Changes

Let’s go back and look at the first part of Rhythm Changes.

First listen, then analyze the chords that we can.

Note a couple of things in what we have so far:

The first chord in both lines (m. 1 and m. 5) is marked as a Bb6. This does not mean a first inversion Bb chord. It refers to a Bb chord with an added 6th: Bb-D-F-G. We will ignore the added note in our analysis to make it a bit more diatonic.

Most of the progression analyzed so far consists of down a fifth progressions: iii -> vi -> ii -> V7.

There are two chords that we have not analyzed – highlighted in purple (C#^o7) and blue (G7). The G7 chord is analyzed on another page in this Manual (Secondary Dominants – Example 1); it is a V7/ii in the key of Bb which will be filled in on the following analyses of this example.

The purple chord des not have the same jazz chord indication as it did before. Previously, it was indicated as a E^o7, but now it is now indicated as a C#^o7/E. These two chords are the same chord; E^o7 and C#^o7 are enharmonic to each other. The C# and the Db are enharmonic and so the chord will sound the same. Therefore, this change was made to make its function more apparent.

The following analysis will concentrate on the C#^o7/E chord.

Secondary Leading Tone Chord

We already know what the root and quality of the chord highlighted in purple: C# and fully diminished 7th chord.

In the key of this example, Bb major, the only place we would have a fully diminished 7th chord is on the scale degree 7. C# is not scale degree 7 in this key; the 7th scale degree is A. Therefore, this chord is not diatonic to our key.

We know from our definition of secondary dominants, that a fully diminished seventh chord can function as a secondary dominant (a leading tone chord). In order to function this way, the chord should resolve as a vii^o in a key – the root of the vii^o chord would resolve up a half-step to tonic.

If the C#o7 is vii^o7 in some key, the root, C#, would resolve up a half-step to D. The chord would be vii^o7 in the key of D minor.

In our version of Rhythm Changes, the C#^o7 chord does resolve to a D minor chord (in first inversion since the F is in the bass) which functions as a ii chord in the key of Bb.

Therefore, the C#^o7 chord is analyzed as a vii^o7/iii – a leading tone fully diminished seventh chord in the key of iii (D). It is also in first inversion since the E is in the bass.

Therefore, the final analysis of this example, is seen below:

The C#^o7 chord is a secondary leading tone seventh chord – a vii^o7/iii.

Summary

If there is a chord that is a diminished, half-diminished seventh, or fully diminished chord, then it could be a secondary leading tone (secondary dominant) chord (X/Y) that functions as a vii^o, vii^ø7, vii^o7 (the X chord).

Resolve the root of this chord up a half-step (as if it were scale degree 7 going to 1). Then look to the root of the next chord (Y); is this note what the root of the vii^o chord should resolve to? If so, then analyze it as a secondary leading tone (dominant) – vii^o/Y.