Your static is wrong.
your static (i,o) will translate the local inside address 2.2.2.5 to 1.1.1.2 on the outside.
Remove it and add:
static (i,o) 2.2.2.3 1.1.1.2 net 255.255.255.255
(This will translate the address 1.1.1.2 to 2.2.2.3 on the outside.)
if you ping 2.2.2.5 from R2, the pix will translate it to 2.2.2.3 on the outside, and R5 will respond to 2.2.2.3, and the PIX will translate back to 1.1.1.2
Assuming this is a lab/test (non-production environment) you can also turn on debug icmp trace on the pix or debug ip icmp on the routers.
The nat(inside) 1 and global(outside) 1 would not be used by the firewall, since the static NAT would take priority.