Ca6[Cr2N6]H, the first quaternary nitride-hydride.

The novel quaternary nitride-hydride Ca(6)[Cr(2)N(6)]H was synthesized at 1000 degrees C in sealed niobium or stainless steel tubes. It crystallizes in the space group R3 (No. 148, Z = 3) with lattice constants (A) a = 9.0042(2) and c = 9.1898(3) and contains the complex anion [Cr(2)N(6)](11)(-) with a short chromium-chromium bond length of 2.26 A. 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.