Upgrading Mac mini (Mid 2011) RAM
I found this site here.
It appears that your mac can only use the 1333mhz ram sticks, the 2012 models can work with the faster memory.
The site also states that 16gb is not suported but unofficial it will work anyway.

In this answer a similar question is answered, if it works it wil run at 1333mhz since your ram slots can't go any faster.
But since macs are really picky about the memory you use there is a big chance it won't work at all.