[itimpi]

Sounds like this is a problem with the citation managers then. They should be able to import an .opf file as it is a standard format.

The alternative would be to write a tool of your own that can extract the data from the .opf file and put it into a format that the tools you want to use expect.

You can always raise a ticket covering a Calibre enhancement request for a new option to export metadata in some other formats. I am not sure that integration to citation managers was ever a high priority requirement for Calibre but that does not stop you raising it as something you would like to see.

Note that if you use the command line tools the calibre-db command already allows data to be exported in csv format.