Turns out it may be possible...
https://discussions.apple.com/thread/6472306
Leopard requirements/10.5.x...
* Mac computer with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor
minimum system requirements
* 512MB of memory (I say 1.5GB for PPC at least, 2-3GB minimum for IntelMacs)
* DVD drive for installation
* 9GB of available disk space (I say 30GB at least)
Classic/OS9 Apps no longer supported.
Trouble is Apple no longer sells it, check eBay & such for the Retail version, not the Gray Discs...
http://www.ebay.com/sch/i.html?_nkw=mac+os+x+leopard+retail+10.5
There are workarounds if the 867MHz CPU is the only hangup...
http://sourceforge.net/projects/leopardassist/
http://lowendmac.com/osx/leopard/unsupported.html
Then you'd need iLife 09.