HELP Leo with life saving surgery!

This precious little boy was found after a neighbor moved away and left their cats outside to their own fate. I found this one outside scared and unable to put weight on his back foot. I took him to the vet and had several x_rays taken. The vet determined that he had a compound fracture (broken into 3 or more pieces) and that the injury could be the result of abuse/neglect by the previous owner. Without surgery, the bone will never set properly and the site may become seriously infected. This could result in the loss of our new family member. Please help us start a better life for this poor baby.