I don’t believe that the AX4 supports any of the EMC data mirroring software which would run on the array. Also you’ll have a problem buying a new AX4 for the other site as that product has been replaced. You’ll probably need to upgrade to a newer array the VNXe which should support data mirroring and then you’ll need a VNXe for your DR site as well.
Depending on what the application is that is running on the servers it might be easier (and cheaper) to look at doing the site to site data replication from the server side of things. I’d recommend bringing in someone who has done stuff like this before to assist you. While consultants like this aren’t cheap in the long run they are cheaper than doing this wrong.
(Do note I’m a consultant, so while I’d love your business you don’t have to use me.)