Chloramines not as deadly as chlorine...
Wrong. Chloramine is created by chemically bonding Chlorine and ammonia, the purpose of which is to produce a more stable additive to tap water which will prevent biological functions (mostly bacterial growth is targeted) and prevent water-born contamination more dependably. (The ammonia keeps the Chlorine from leaving the water easily.) Water with only Chlorine added to it will quickly lose the Chlorine (via off-gassing), which is why you can use water in aquariums after simply aerating it with an air stone and air pump, or by creating surface turbulence, which increases gas exchange. Actually, just leaving water uncovered for a day will get rid of simple Chlorine, and the ease with which Chlorine leaves water is the reason Chloramine was developed and came into common use in the mid/late '80s. This is also why aquarium product companies came out with new tap-water treatments such as Kordon's "Amquel" in addition to their "Novaqua" product, because simple de-chlorinators alone couldn't break the chemical bond and make the water safe for aquatic animals.
Chloramine can only be quickly removed from water by first breaking the chemical bond between the ammonia and the Chlorine, after which each must be dealt with separately, since both are toxic to aquatic animals. I'm not sure how you come to the conclusion that "Chloramines not as deadly as chlorine", since they both do the same thing, except that chloramine does it far longer than basic Chlorine by itself. If they could, I think your frogs and tadpoles would tell you otherwise, as well.
Amphibians take in much of the oxygen they need through their skin, which also means that they are more susceptible to chemicals in the water than even some fish (not including scaleless fish, which for the same reason--very porous skin--are more sensitive to some medications than other fish). As long as their skin remains moist/wet, they are able to take in enough oxygen to stay alive. Some younger tadpoles may possibly have more difficulty than older ones (?), but any frog/froglet with viable legs would be fine if kept moist. Next time, if in a similar situation, it would be better to leave the frogs and tadpoles with even just enough water to cover the tadpoles (or even less) and make sure you detoxify any water before you add it to their aquarium. Always keep in mind how sensitive most amphibians' skin is, which is why they are considered ecological indicators--whatever pollutants are in the environment will be quickly absorbed by the amphibians through their skin. This is also why it is best to not handle them with your bare hands--especially the ones with perpetually moist skin; the salts and oils from your own skin don't do them any good at all. Now if it was a dry-skinned toad, then I'd say it's best to not handle them for YOUR sake, due to the toxins some toads produce in their skin, not to mention that they'll likely pee on you and give you warts! (sic)