Digital Mosaic is a vendor in the Requirements space, and they have released a white paper to communicate the importance of Requirements to Executive-level Management. I recommend its use if you need to do just that... and it is also just a well-written piece, so you can follow the link below to have a look.
TITLE: "The Executive Briefing on the Issues Surrounding Getting Business Requirements Right"
PUBLISHER: Digital Mosaic
TYPE: White Paper