Clathrates are different, they are not eutectics. If you try to freeze them, they separate into methane gas and water ice.

Metals can alloy with each other because the shared electron layer "glues" small imperfections in crystals where different metals meet. Can frozen ammonia behave similarly? Liquid ammonia can solvate free electrons, so perhaps frozen ammonia also can?

It'd be interesting to actually try experiments with frozen ammonia.

that's a fascinating idea! frozen electrides! it's a lot freezier than methane (195 kelvin, a difference large enough to make a methane eutectic much less likely) to the point where you might even be able to freeze it with convenient and safe dry ice rather than liquid nitrogen. and, i don't know, maybe if dry ice by itself won't do the trick, maybe dry ice mixed with liquid ammonia will. trying to buy anhydrous ammonia around here gets you put on a list, though, so i'm gonna opt out of this one

there are a lot of solvated ionic eutectics with atmospheric-pressure water ice, despite the absence of metallic bonding