Donald Statz ([log in to unmask])  wrote:

>Mozart wrote only three vocal/liturgical works from the time of his
>arrival in Vienna in 1781 up to his death in 1791: Mass in C minor, Ave
>verum Corpus, and the Requiem.  It is likely that Mozart started work on
>the Mass in C minor shortly after his marriage to Constanze in 1782; Mozart
>had promised that he would perform a Mass in her honor when he took her to
>Salzburg to meet his father.  However, the work was not complete by that
>time and never was completed.

I believe that scholars now believe the Kyrie K.341 was not written for the
Elector of Munich, but was either the beginning of a new Missa Solemnis or
a piece to celebrate his appointment to the St Stephen's Cathedral as an
assistant.  The date of composition is now believed to have been maybe as
late as 1791.  There are a few other extant Kyries that date from Mozart's
Vienna period that were never finished, I do not know how much of the
fragments are finished in terms of being reconstructed, but I do recall
reading that most of these are in the key of D Minor.  Mozart was on the
cusp of renewing his ties with liturgical music just when he died.
Interesting that with this appointment at St Stephen's he never finished
the Great Mass.

Kim Patrick Clow