Secondary Dominants

Identifying Secondary Dominant Functions

A major triad or Mm 7^th chord with a secondary dominant function lies a perfect 5^th above some other pitch. The note a perfect 5^th below it serves as a temporary tonic for the purpose of analysis. This tonicized pitch acts as a tonic to the secondary dominant chord, which may also be referred to as an applied dominant. When diatonic minor chords in a major key (ii, iii, and vi) are altered to become major chords with an accidental raising the 3^rd, they often function as secondary dominants. This is confirmed if the chord that follows is down a P5^th.

It is analyzed as “V of x”, and the x can represent a diatonic or altered chord in the key. A slash is used to show the relationship between the chords. In the key of C major, ii = D minor, and V/ii = A major, a P5 above the note D. The C# used to raise the 3^rd of the diatonic minor triad built on A is the leading tone in the key of D. The raised 3^rd of the secondary dominant is always a half-step below the tonicized pitch.

The most common secondary dominant chords in the key of C major are V/ii = A major; V/iii = B major; V/V = D major; and V/vi = E major. These relationships are common to all major keys. The leading tone chord, vii^o, is not tonicized because of the instability of the diminished chord.

In general, a diatonic chord in a major key that would ordinarily be minor with a raised 3^rd can usually be analyzed as a secondary dominant. The exception to this rule is the V7/IV chord. This Mm7^th chord is built on the tonic pitch, and the chromatic alteration is a lowered 7^thin the key. In this case the secondary dominant chord contains a lowered pitch, and it is always built on the tonic of the key. The quality of a Mm7^th chord dictates that it can only be analyzed as a V7, and not as a tonic function.

Spelling Secondary Dominant Chords

Given a scale degree, consider that note the tonic of the key to which the secondary dominant belongs. Determine the dominant, or V7 chord in that key, and spell it accordingly. The upper or lower case Roman Numeral to the right of the slash indicates the major or minor quality of a triad built on that scale degree in a key. Let’s apply this information to spell the V7/III chord in the key of A minor. The mediant, or III chord is C major, and it’s dominant is G7 (G-B-D-F). A figured bass symbol may be included to invert the chord.

Sequences of Secondary Dominant Chords

Secondary dominant chords most often resolve to the chord built on the tonicized note. However, it is common to see chains of secondary dominants in a circle of fifths progression. This sequence of chords in C major might consist of E7 – A7 – D7 – G7 – C, analyzed in Roman Numerals as V7/V7/V7/V7/I.

In jazz and popular music the ii7 – V7 sequence is often used to tonicize any diatonic or non-diatonic chord. This is referred to as a “two-five of ” the following chord. These two-fives are sprinkled generously throughout most jazz reharmonizations. They often do not resolve to the tonicized pitch, and may be found in a cycle of downward 5^th or downward 2^nd progressions.

Voice-Leading Secondary Dominant Chords

Resolve each note according to its tendency, or chromatic inflection. Raised pitches continue upwards, as a general rule, and lowered pitches move down. The altered major 3^rd of the secondary dominant chord resolves up by half-step. The minor 7^th of the Mm7 chord typically resolves down by half-step.

Secondary Dominant Example