Barium Osminitrite, BaOs(NO₂)₅

Barium Osminitrite, BaOs(NO₂)₅.H₂O, is obtained by the action of barium chloride on a hot aqueous solution of potassium osminitrite and crystallising at temperatures above 15° C. It yields yellow plates.

At temperatures below 15° C. the salt separates out as amber- yellow needles containing four molecules of water.

Osminitrites of silver (golden yellow), strontium (orange), calcium. (orange-yellow), magnesium (sulphur-yellow), and zinc (orange-yellow) have been prepared.