Department Chemie, Lehrstuhl für Anorganische Festkörperchemie, Ludwig-Maximilians-Universität München, 81377 München, Germany.
Inorg Chem. 2012 Feb 20;51(4):2366-73. doi: 10.1021/ic2023677. Epub 2012 Jan 11.
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). 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.
碱土二氮化物 M(AE)N(2)（其中 M(AE) = Ca、Sr 和 Ba）是通过一种新的合成方法合成的，即在高压/高温条件下，多砧压机中控制相应叠氮化物的分解。 hitherto unknown calcium diazenide（空间群 I4/mmm（No. 139），a = 3.5747(6) Å，c = 5.9844(9) Å，Z = 2，wR(p) = 0.078）的晶体结构是根据粉末 X 射线衍射数据以及 SrN(2)和 BaN(2)的晶体结构数据来解决和细化的。因此，CaN(2)与 SrN(2)（空间群 I4/mmm（No. 139），a = 3.8054(2) Å，c = 6.8961(4) Å，Z = 2，wR(p) = 0.057）同型，相应的碱土金属乙炔化物（M(AE)C(2)）呈四方扭曲 NaCl 结构类型结晶。根据文献数据，BaN(2)在空间群 C2/c（No. 15）中采用更扭曲的结构，a = 7.1608(4) Å，b = 4.3776(3) Å，c = 7.2188(4) Å，β = 104.9679(33)°，Z = 4，wR(p) = 0.049）。CaN(2)（SrN(2) 1.239(4) Å，BaN(2) 1.23(2) Å）中 1.202(4) Å 的 N-N 键长与双键氮二单元相对应，确认二氮化物离子N(2)。三种碱土金属二氮化物的原位粉末 X 射线衍射温度依赖性导致在较高温度下形成相应的亚氮化物 M(AE(2))N（M(AE) = Ca、Sr、Ba）。FTIR 光谱显示约 1380 cm(-1)处的一个带归因于二氮化物单元的 N-N 伸缩振动。电子结构计算支持碱土金属二氮化物的金属性质。
