Titanium Hydride Complex BaCa2Ti2H14 with 9-Fold Coordination
Titanium Hydride Complex BaCa2Ti2H14 with 9-Fold Coordination
复制标题
九重配位氢化钛配合物 BaCa2Ti2H14
DOI：
10.1021/acs.inorgchem.9b02810
复制
发表时间：
2020
影响因子：
4.6
通讯作者：
Hiroi Zenji
中科院分区：
文献类型：
--
作者：
Yajima Takeshi;Nakajima Hotaka;Honda Takashi;Ikeda Kazutaka;Otomo Toshiya;Takeda Hikaru;Hiroi Zenji
本文报道了一种9配位的新型钛氢化物化合物BaCa2Ti2H14的高压合成和晶体结构。它包含一个独特的双核[Ti2H14]6-络合物，它由一对Ti4+离子组成，每个离子都由9个氢化物配位在单冠正方形反棱镜中，不同于[MH9]x−的单核三冠三棱柱中已知的9重配位。二核氢化物是通过在四个桥联的Ti-H-Ti键上的三中心两电子键来稳定的，以弥补Ti4+离子中价电子的缺乏。光学测量表明，BaCa2Ti2H14是一种禁带宽度为2.25 eV的带状绝缘体。密度泛函理论计算表明，价带顶部由H-1s衍生态主导，正如9重配位所预期的那样，这将为电子性质提供一个游乐场，如当掺杂空穴载流子或在高压下时的高T_c超导电性。
We present the high-pressure synthesis and crystal structure of a novel titanium hydride complex, BaCa2Ti2H14, with 9-fold coordination. It comprises a unique dinuclear [Ti2H14]6–complex that consists of a pair of Ti4+ions each coordinated by nine hydrides in the monocapped square antiprism, distinguished from the known 9-fold coordination in the mononuclear tricapped trigonal prism of [MH9]x−. The dinuclear hydride complex is stabilized by three-center two-electron bonding at the four bridging Ti–H–Ti bonds to compensate for the lack of valence electrons in the Ti4+ions. Optical measurements show that BaCa2Ti2H14is a band insulator with a wide band gap of 2.25 eV. Density functional theory calculations reveal that the top of the valence band is dominated by H-1s-derived states, as expected from the 9-fold coordination, which would present a playground for electronic properties such as high-Tcsuperconductivity when doped with hole carriers or under high pressure.