Here are my experiences with thionyl chloride, with which I was doing a few months of chemistry at one point. When I got it, I was told it reacts violently with water, so of course I made myself a controlled explosion in a fume hood to see how reactive it was. Got a very nice mushroom cloud.
Second, I placed a capped container with used thionyl chloride in a vented chem storage closet. Yes, I stored the stuff in all-plastic bottle with parafilm etc. Problem was, the storage closet was metal, and not covered with any protective plastic. Next morning, the cabinet and all metal objects in the cabinet were thoroughly corroded.
So yeah, using SOCl2 batteries in your Leica may not be the best option Just tuck your Leica somewhere nice, warm and soft (between the buttocks perhaps?) and withdraw it right when you're ready to shoot.