Ca₆[Cr₂N₆]H, the First Quaternary Nitride−Hydride

The novel quaternary nitride−hydride Ca6[Cr2N6]H was synthesized at 1000 °C in sealed niobium or stainless steel tubes. It crystallizes in the space group R3̄ (No. 148, Z = 3) with lattice constants (Å) a = 9.0042(2) and c = 9.1898(3) and contains the complex anion [Cr2N6]11- with a short chromium−chromium bond length of 2.26 Å. To our knowledge, this is the first example of a non-nitrogen-bridged chromium−chromium dimer in an extended structure compound. Magnetic susceptibility measurements reveal the compound to be paramagnetic at room temperature and with a broad antiferromagnetic ordering centered around 55 K.