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Anybody happen know if the #vio7 chord has a name like the Italian, French, and German augmented sixth chords? I'd like to read up on it and how it is used in chord progressions, but my searches aren't turning up good results.

And what about the vi* chord? Not sure what that is supposed to be, especially since it sits at the center of the circle with the I chord.

I found the following chord progression diagram online somewhere, but I can't seem to find it again -- not that it had much explanation along with it anyway!

Thanks!

Chrord progression chart

etisdale
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  • Based on the diagram, #vio7 is a pre-dominant chord, so its function in a chord progression would be the same as those around that ring -- to lead to a dominant-function chord: V or viio. – Aaron Dec 13 '20 at 01:17
  • The * with the vi chord, I imagine was a pointer to a footnote saying that vi can fill in for I in some chord progressions. When this happens, it is frequently a "deceptive cadence": e.g., V - vi, rather than V - I. – Aaron Dec 13 '20 at 01:19
  • Thanks. Any further idea as to how the #vio7 chord is used? With the N6 chord, for example, it's usually used in place of a ii chord in its first inversion. – etisdale Dec 13 '20 at 03:24
  • An educated guess (but only a guess) is it would be used as viio/vii or a common-tone diminished seventh leading to V. – Aaron Dec 13 '20 at 03:33
  • Yes!

    "A fully diminished seventh chord which progresses to a major triad or dominant seventh chords whose root is the same as one of the notes of the o7 chord. Examples are #iio7 (or enharmonic #ivo7) progressing to I and #vio7 progressing to V(7)."

    "The chords function as embellishments of the chord that follows (e.g., the #ii/#iv embellishes the I and the #vi embellishes the V)."

    http://personal.kent.edu/~sbirch/Common/Encyclopedia/Voice%20Leading/Common-tone%20Diminished%207th%20Chords.htm

     – etisdale Dec 13 '20 at 03:46
  • Cool. May I include that in an answer to the question? – Aaron Dec 13 '20 at 05:26
  • #vi°7 can easily be a secondary dominant (of "vii" (e.g. B minor for C major), enharmonically of ii (e.g. D minor for C major), enharmonically of IV (e.g. F major for C major)) as well as a common-tone diminished 7th (e.g. of V, of I)). – Dekkadeci Dec 13 '20 at 14:55
  • Also, if I'm interpreting this diagram accurately and the center is tonic-function chords, the next circle is dominant-function chords, the next circle is predominant chords that strongly pull to the dominant, and the outermost circle is predominant chords that pull away from the dominant, I don't think most of the chords are correctly assigned - the augmented 6ths and V/V virtually always resolve to the dominant, while none of the other chords on their circle always do; V7/IV never resolves to the dominant, while iii can and vi often does. – Dekkadeci Dec 13 '20 at 15:00
  • @Aaron Sure thing! – etisdale Dec 14 '20 at 17:25
  • @Dekkadeci I'm still learning this stuff, particularly with respect to the augmented sixth chords, that common-tone diminished seventh, etc., but don't the other chords in the circle along with the augmented sixths strongly pull toward the dominant? For example, there is the ii -> V and the V/V -> V. – etisdale Dec 14 '20 at 17:25
  • @etisdale - While V/V pulls to the dominant very strongly, ii only weakly pulls to the dominant. ii can easily be immediately followed by V, IV, and vi, for example. – Dekkadeci Dec 15 '20 at 12:48

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Explanation of the diagram

The diagram is a loose representation of the functional tendencies of various chords.

  1. At the center is the tonic and the relative minor chord, which can substitute for it, for example, in a deceptive cadence (V-vi). The parentheses around the vi indicate it as a "substitute" chord but one which does not truly replace the tonic. The asterisk likely points to a footnote not included explaining the vi chord's substitute nature.
  2. The innermost ring comprises chords that primarily serve dominant (i.e., moving to the tonic) functions.
  3. The next ring is chords that tend to act as pre-dominants.
  4. The outer ring is chords that can serve as pre-predominants or which can supplant the tonic (i.e., have at least two common tones), typically as part of a tonic expansion.

The #vio7 chord

Within the context of the diagram, this chord can function in two ways: viio7/vii or c.t.o7/V. "c.t." stands for "common tone", and you can read more about common-tone diminished chords here, Diminished chord constructed over the tonic degree?, and you can find a list of additional SE questions/explanations here.

Outside of SE, Wikipedia mentions common-tone diminished seventh chords, this web page discusses the #vi chord specifically, and Florida State professor Nancy Rogers has posted a handout on the subject.

The #vio7 does not have a unique name in the way that the aug6 and Neapolitan chords do.

Aaron
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    One additional usage common in jazz styles: as an upper leading-tone diminished 7th chord resolving downward by half-step to ii7. In the key of C, this would be Ebdim7 going to Dm7! – user45266 Dec 15 '20 at 00:34