Updating 10.6.8 system

Hi there,

I'd like to update my system, I'm currently on OSX 10.6.8. I think Yosemite is too advanced for my system. Can someone please recommend a system based on the specs below?

Model Name: iMac

Model Identifier: iMac11,1

Processor Name: Intel Core i5

Processor Speed: 2.66 GHz

Number Of Processors: 1

Total Number Of Cores: 4

L2 Cache (per core): 256 KB

L3 Cache: 8 MB

Memory: 12 GB

Processor Interconnect Speed: 4.8 GT/s

Boot ROM Version: IM111.0034.B02

SMC Version (system): 1.54f36

Serial Number (system): W89523FX5PJ

Hardware UUID: 28A7E164-D7C8-5E2D-ACFD-40B59986152E

Many thanks,

Luisa