A Leading tone (L) transformation occurs between two chords that share two notes that stay the same with the third note moving by a half step. If starting with a major triad, move the root down a half step; if starting with a minor triad, move the fifth up a half step.
The two chords will share two notes and the other notes will be a half-step apart.
For example, a C major triad will transform to an E minor triad through a Leading tone (L) Transformation.
For this transformation, think of two notes staying the same (in this case, the E and the G) and the other note moving by half step (C to B) – like a tonic to leading tone is a half step.
A Leading tone (L)transformation, e.g., C major -> E minor, can be shown as:
Example
Measures 33-38 (right hand) of Prokofiev’s Visions Fugitives, Op 22, No 4 is an example of an L (Leading tone) relationship.
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The two chords in measures 33-38 alternate between a C major triad (in first inversion) and an E minor triad.
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This L relationship can be seen on the Tonnetz:
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