Among all C-, N-, and O-centered polyradicals, high-spin nitrenes possess the largestm agnetic anisotropy and are of considerable interest as multi-level molecular spin systems for explorationo fo rganic molecular magnetism and quantum information processing. Although the first representatives of quintet and septet nitrenes were obtained almost 50 years ago, the experimental and theoretical studies of these highly reactive speciesb ecamep ossible only recently ,o wing to new achievements in molecular spectroscopy and computationalc hemistry.M eanwhile, dozens of various quintet dinitrenes and septettrinitrenes were successfully characterized by IR, UV/Vis,a nd EPR spectroscopy,t hus providing important information about the electronic structure, magnetic properties and reactivity of these compounds.