Are there emotions that motivate pattern completion?
Canonical models of emotions in relation to pattern comclusion can not be provided.

The emotional of the musical sequences completion are directly related to the tonality.

Emotions related to the tonality are presented in the semantic memory.

It is possible the study of a partial mapping that relates tonality and emotions.

The best text, in my opinion, is:
Sloboda, John, A. (1985). The Musical Mind: The Cognitive Psychology of Music. 
This is a compilation of numerous research in this area, others very interesting books can be found of this author.