I am trying to write a progression in Cm that modulates to the minor dominant (Gm). In this progression I think I have written a viio65/v but I am getting unequal 5ths between the bass and alto parts. Is the voice leading in this progression deemed unacceptable in some styles of music like in common practice or baroque style harmony? Are there styles in which this type of progression is avoided? I could have used viio6/v or V43/v but I really like the fully diminished chord.
Why not root position?
There isn't a universal answer to this kind of question. "Acceptable" is determined by style.
If voice leading is the concern, and you run into a voice leading problem, you must change chord voicings.
If chord qualities and sonorities are the concern, then voice leading is subordinated.
Walter Piston says these two things:
- It is customary to resolve the two intervals of the diminished fifths, contracting each to a third, without regard for the doubling that results.
- When the second degree [he means third of the chord] is in the bass it usually resolves to the third degree [he means third of the tonic chord] to avoid a direct fifth on the resolution of the diminished fifth.
So, if we offset the octave of the two
d5/A4 intervals for easier reading, and show root position and first inversion, with their respective resolutions to thirds, we get...
That establishes something of an authoritative acceptability.
But, based on your comments, the particular voicings you have in your example are your preferences, probably for their specific sonorous qualities. By Piston's reckoning, he would probably just call your treatment an irregular resolution. Throughout his Harmony textbook he acknowledges that kind of artistic license. You want to make an artistic choice of vertical sonority taking precedence over voice leading.