Materials Data on Bi4I by Materials Project

Bi4I crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are eight inequivalent Bi sites. In the first Bi site, Bi is bonded in a distorted rectangular see-saw-like geometry to three Bi and one I atom. There are two shorter (3.08 Å) and one longer (3.09 Å) Bi–Bi bond lengths. The Bi–I bond length is 3.64 Å. In the second Bi site, Bi is bonded in a 4-coordinate geometry to three Bi and three equivalent I atoms. There are one shorter (3.07 Å) and two longer (3.09 Å) Bi–Bi bond lengths. There are one shorter (3.62 Å) and two longer (3.70 Å) Bi–I bond lengths. In the third Bi site, Bi is bonded in a 4-coordinate geometry to four Bi atoms. There are a spread of Bi–Bi bond distances ranging from 3.07–3.57 Å. In the fourth Bi site, Bi is bonded in a distorted rectangular see-saw-like geometry to four Bi atoms. The Bi–Bi bond length is 3.55 Å. In the fifth Bi site, Bi is bonded in a 4-coordinate geometry to four Bi atoms. The Bi–Bi bond length is 3.12 Å. In the sixth Bi site, Bi is bonded in a 2-coordinate geometry to two equivalent Bi and two I atoms. Both Bi–Bi bond lengths are 3.11 Å. There are one shorter (3.12 Å) and one longer (3.17 Å) Bi–I bond lengths. In the seventh Bi site, Bi is bonded in a 4-coordinate geometry to four Bi atoms. The Bi–Bi bond length is 3.56 Å. In the eighth Bi site, Bi is bonded in a 4-coordinate geometry to four Bi atoms. There are two inequivalent I sites. In the first I site, I is bonded in a distorted single-bond geometry to four Bi atoms. In the second I site, I is bonded in a single-bond geometry to two Bi atoms.

Bi₄I晶体属于单斜晶系（monoclinic）C2/m空间群（space group），其晶体结构为三维骨架结构。存在8个不等价的铋（Bi）原子位点。在第一个铋原子位点中，铋原子以扭曲矩形跷跷板状配位构型，与3个铋原子和1个碘（I）原子成键。该位点存在2条较短的Bi-Bi键（键长3.08 Å）与1条较长的Bi-Bi键（键长3.09 Å），Bi-I键键长为3.64 Å。在第二个铋原子位点中，铋原子采取四配位构型，与3个铋原子及3个等价的碘原子成键。该位点存在1条较短的Bi-Bi键（3.07 Å）与2条较长的Bi-Bi键（3.09 Å）；Bi-I键则包含1条较短键长（3.62 Å）与2条较长键长（3.70 Å）。在第三个铋原子位点中，铋原子采取四配位构型，仅与4个铋原子成键，其Bi-Bi键距分布范围为3.07~3.57 Å。在第四个铋原子位点中，铋原子以扭曲矩形跷跷板状配位构型与4个铋原子成键，Bi-Bi键长为3.55 Å。在第五个铋原子位点中，铋原子采取四配位构型，与4个铋原子成键，Bi-Bi键长为3.12 Å。在第六个铋原子位点中，铋原子采取二配位构型，与2个等价铋原子及2个碘原子成键。两条Bi-Bi键长均为3.11 Å，Bi-I键则分别为1条较短的3.12 Å与1条较长的3.17 Å。在第七个铋原子位点中，铋原子采取四配位构型，与4个铋原子成键，Bi-Bi键长为3.56 Å。在第八个铋原子位点中，铋原子采取四配位构型，与4个铋原子成键。体系中存在2个不等价的碘（I）原子位点：在第一个碘原子位点中，碘原子以扭曲单键配位构型与4个铋原子成键；在第二个碘原子位点中，碘原子以单键配位构型与2个铋原子成键。