Sending ctrl-space with SendKeys in C #?

I am doing some basic things like automation and I need to send a ctrl-space to the desktop (I need to make sure nothing is selected so that when I do SendKeys.SendWait("+{F10}");

I get a generic desktop menu and not one for any particular file). I've tried the obvious things (actual space, "SPACE", "SPACE") and none of them work, they all give me an ArgumentException. Does anyone know the correct way to do this?

C # to .NET 4.0 and Windows 7, if it matters.