Cool. Thanks for clearing this up. So my understanding now is vii dim does not have a dominant. Would it be safe to also say
- ii (dim) chord on the natural minor
- ii (dim) and vii (dim) chord on harmonic minor
- vi (dim) and vii (dim) chord on melodic minor
also have no dominant V chord associated with as they are all diminished
Not really. The fully diminished chord doesn't have a dominant, since it is, in effect, the V7 with the added tension of the b9. Obviously, you can create a little cycle and prepare it from a fifth above, but it's not a "key" in itself.
You can't resolve to an unresolved "chord": for the simple reason that it's not a tonality. Its only reason for existing is because of the tensions inherent in it.
And one cannot resolve to a diminished or a half-diminished chord: for the reason that it's not a tonality.
That's why there are problems in pop or rock music, or blues, where a minor 7 is sometimes added to make a given chord sound "crunchy."
But, like including the maj7 in a voicing, it's possible ones ears can adjust, as is the case with establishing a "key" with extensions to the 13 and the m7.
But it's not really a tonality: you have the tritone in the chord, and it must be resolved.
I did get quite a bit out of the following video, from here: I can't verify, but it's pretty good information about preparing for the dominant.
And, as you know, that very often is going to be a disguised IV chord, in the shape of a half-diminished ii, and, as one sees, it's possible to omit the V7 entirely.
That's one of the reasons that the later opera of Scriabin appears so odd and, at least for me, is tricky to sight read: if you have a chord spelled like, C, F#, and Bb, which is meaningless, it's not any kind of "key" or tonality. So, you have these odd spellings as in Scriabin, with no key signature at all and these odd accidentals added in an ad hoc fashion.
There may be a greater design to it, as in Scriabin, perhaps, but it's not evident when reading off the page.
/* edit, I don't actually know why Dr. Monahan analyzes what seem to me voice leading "tricks" and disguises for the plagal IV - I or IVm - I, but SM makes a good case for what one hears in music all the time, and his notation including melody and bass is convenient.
I don't often watch youtube videos, but for me it's an exception: good stuff. */