Synthesis of alkaline earth diazenides M(AE)N2 (M(AE) = Ca, Sr, Ba) by controlled thermal decomposition of azides under high pressure.

The alkaline earth diazenides M(AE)N(2) with M(AE) = Ca, Sr and Ba were synthesized by a novel synthetic approach, namely, a controlled decomposition of the corresponding azides in a multianvil press at high-pressure/high-temperature conditions. The crystal structure of hitherto unknown calcium diazenide (space group I4/mmm (no. 139), a = 3.5747(6) Å, c = 5.9844(9) Å, Z = 2, wR(p) = 0.078) was solved and refined on the basis of powder X-ray diffraction data as well as that of SrN(2) and BaN(2). Accordingly, CaN(2) is isotypic with SrN(2) (space group I4/mmm (no. 139), a = 3.8054(2) Å, c = 6.8961(4) Å, Z = 2, wR(p) = 0.057) and the corresponding alkaline earth acetylenides (M(AE)C(2)) crystallizing in a tetragonally distorted NaCl structure type. In accordance with literature data, BaN(2) adopts a more distorted structure in space group C2/c (no. 15) with a = 7.1608(4) Å, b = 4.3776(3) Å, c = 7.2188(4) Å, β = 104.9679(33)°, Z = 4 and wR(p) = 0.049). The N-N bond lengths of 1.202(4) Å in CaN(2) (SrN(2) 1.239(4) Å, BaN(2) 1.23(2) Å) correspond well with a double-bonded dinitrogen unit confirming a diazenide ion [N(2)](2-). Temperature-dependent in situ powder X-ray diffractometry of the three alkaline earth diazenides resulted in formation of the corresponding subnitrides M(AE(2))N (M(AE) = Ca, Sr, Ba) at higher temperatures. FTIR spectroscopy revealed a band at about 1380 cm(-1) assigned to the N-N stretching vibration of the diazenide unit. Electronic structure calculations support the metallic character of alkaline earth diazenides.

[1]  R. Riedel,et al.  Synthesis of cubic zirconium and hafnium nitride having Th3P4 structure , 2003, Nature materials.

[2]  Toshiro Maruyama,et al.  Copper nitride and tin nitride thin films for write‐once optical recording media , 1996 .

[3]  Y. Prots,et al.  Speciation of nitrogen – [N3–] and [N22–] – in binary compounds , 2002 .

[4]  M. Carpenter,et al.  Some simplifications to multianvil devices for high pressure experiments , 1990 .

[5]  Reinhard K. Kremer,et al.  Preparation, Crystal Structure, and Properties of Barium Pernitride, BaN2 , 2001 .

[6]  Sandro Scandolo,et al.  OsN2: Crystal structure and electronic properties , 2007 .

[7]  Russell J. Hemley,et al.  Synthesis and characterization of a binary noble metal nitride , 2004, Nature materials.

[8]  H. Kawaji,et al.  Superconductivity at 25.5 K in electron-doped layered hafnium nitride , 1998, Nature.

[9]  S. Endo,et al.  The Generation of Ultrahigh Hydrostatic Pressures by a Split Sphere Apparatus , 1970 .

[10]  Zhongyuan Liu,et al.  Crystal structure and physical properties of OsN 2 and PtN 2 in the marcasite phase , 2007 .

[11]  Babak Sadigh,et al.  Synthesis and Characterization of the Nitrides of Platinum and Iridium , 2006, Science.

[12]  D. Rubie.  Characterising the sample environment in multianvil high-pressure experiments , 1999 .

[13]  Paul F. McMillan,et al.  New materials from high-pressure experiments , 2002, Nature materials.

[14]  H. Huppertz.  Multianvil high-pressure / high-temperature synthesis in solid state chemistry , 2004 .

[15]  Yanming Ma,et al.  Ultra-incompressible phases of tungsten dinitride predicted from first principles , 2009 .

[16]  R. Dronskowski,et al.  Nature of N-N bonding within high-pressure noble-metal pernitrides and the prediction of lanthanum pernitride. , 2010, Journal of the American Chemical Society.

[17]  Richard Dronskowski,et al.  Crystal orbital Hamilton populations (COHP): energy-resolved visualization of chemical bonding in solids based on density-functional calculations , 1993 .

[18]  V. Lo,et al.  Investigation of tetragonal ReN2 and WN2 with high shear moduli from first-principles calculations , 2010 .

[19]  R. F. Walker,et al.  Physics and chemistry of the inorganic azides , 1977 .

[20]  B. Sadigh,et al.  Synthesis and characterization of nitrides of iridium and palladium , 2008 .

[21]  J. Tse,et al.  Stability, elastic and electronic properties of palladium nitride , 2010, Journal of physics. Condensed matter : an Institute of Physics journal.

[22]  David Walker,et al.  Lubrication, gasketing, and precision in multianvil experiments , 1991 .

[23]  G. Auffermann,et al.  SrN und SrN2: Diazenide durch Synthese unter hohen N2‐Drücken , 2001 .

[24]  H. Skriver.  The LMTO Method , 1984 .

[25]  W. Schnick,et al.  Group II element nitrides M3N2 under pressure: a comparative density functional study , 2009 .

[26]  S. Louie,et al.  Electronic mechanism of hardness enhancement in transition-metal carbonitrides , 1998, Nature.

[27]  Andersen,et al.  Minimal basis sets in the linear muffin-tin orbital method: Application to the diamond-structure crystals C, Si, and Ge. , 1986, Physical review. B, Condensed matter.

[28]  S. Hull,et al.  Ordering of nitrogen in nickel nitride Ni(3)N determined by neutron diffraction. , 2001, Inorganic chemistry.

[29]  M. Chhowalla,et al.  Thin films of hard cubic Zr3N4 stabilized by stress , 2005, Nature materials.

[30]  R. Rosenfeld.  Nature , 2009, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[31]  J. S. Rowlinson,et al.  PHASE TRANSITIONS , 2021, Topics in Statistical Mechanics.

[32]  R. Dronskowski,et al.  A new phase in the binary iron nitrogen system?--The prediction of iron pernitride, FeN2. , 2011, Chemistry.

[33]  M. Lazzeri,et al.  Interstitial dinitrogen makes PtN2 an insulating hard solid , 2006 .

[34]  Richard Dronskowski,et al.  A first‐principles study on the existence and structures of the lighter alkaline‐earth pernitrides , 2010, J. Comput. Chem..