Materials Data on Mg6Si5 by Materials Project

Mg6Si5 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a distorted trigonal non-coplanar geometry to three Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.75–2.80 Å. In the second Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.68–3.16 Å. In the third Mg2+ site, Mg2+ is bonded to seven Si+2.40- atoms to form edge-sharing MgSi7 pentagonal bipyramids. There are a spread of Mg–Si bond distances ranging from 2.73–3.06 Å. In the fourth Mg2+ site, Mg2+ is bonded in a 4-coordinate geometry to five Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.73–3.07 Å. In the fifth Mg2+ site, Mg2+ is bonded to four Si+2.40- atoms to form distorted corner-sharing MgSi4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.66–2.91 Å. In the sixth Mg2+ site, Mg2+ is bonded in a 3-coordinate geometry to three Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.84–3.06 Å. In the seventh Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to six Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.82–3.21 Å. In the eighth Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to five Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.68–2.85 Å. In the ninth Mg2+ site, Mg2+ is bonded in a 3-coordinate geometry to three Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.67–3.00 Å. In the tenth Mg2+ site, Mg2+ is bonded in a distorted T-shaped geometry to three Si+2.40- atoms. There are two shorter (2.83 Å) and one longer (2.93 Å) Mg–Si bond lengths. In the eleventh Mg2+ site, Mg2+ is bonded in a T-shaped geometry to three Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.71–2.87 Å. In the twelfth Mg2+ site, Mg2+ is bonded in a 4-coordinate geometry to four Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.70–3.19 Å. There are ten inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to five Mg2+ and two Si+2.40- atoms. There are one shorter (2.42 Å) and one longer (2.44 Å) Si–Si bond lengths. In the second Si+2.40- site, Si+2.40- is bonded in a 8-coordinate geometry to five Mg2+ and three Si+2.40- atoms. There are one shorter (2.43 Å) and one longer (2.51 Å) Si–Si bond lengths. In the third Si+2.40- site, Si+2.40- is bonded in a 8-coordinate geometry to six Mg2+ and two Si+2.40- atoms. Both Si–Si bond lengths are 2.42 Å. In the fourth Si+2.40- site, Si+2.40- is bonded in a 1-coordinate geometry to three Mg2+ and three Si+2.40- atoms. There are one shorter (2.41 Å) and one longer (2.45 Å) Si–Si bond lengths. In the fifth Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to five Mg2+ and two Si+2.40- atoms. The Si–Si bond length is 2.38 Å. In the sixth Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to five Mg2+ and two Si+2.40- atoms. There are one shorter (2.40 Å) and one longer (2.42 Å) Si–Si bond lengths. In the seventh Si+2.40- site, Si+2.40- is bonded in a 8-coordinate geometry to six Mg2+ and two Si+2.40- atoms. In the eighth Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to five Mg2+ and two Si+2.40- atoms. In the ninth Si+2.40- site, Si+2.40- is bonded in a 8-coordinate geometry to seven Mg2+ and one Si+2.40- atom. In the tenth Si+2.40- site, Si+2.40- is bonded in a 1-coordinate geometry to five Mg2+ and three Si+2.40- atoms.

六镁五硅（Mg₆Si₅）结晶于三斜晶系P1空间群，整体为三维骨架结构。体系中存在12种不等价的Mg²⁺位点：
1. 第一种Mg²⁺位点中，Mg²⁺以畸变三角非共面配位构型与3个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.75~2.80 Å。
2. 第二种Mg²⁺位点中，Mg²⁺以六配位构型与6个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.68~3.16 Å。
3. 第三种Mg²⁺位点中，Mg²⁺与7个Si⁺2.40⁻原子成键，形成共边MgSi₇五角双锥结构单元，Mg–Si键长分布范围为2.73~3.06 Å。
4. 第四种Mg²⁺位点中，Mg²⁺以四配位构型与5个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.73~3.07 Å。
5. 第五种Mg²⁺位点中，Mg²⁺与4个Si⁺2.40⁻原子成键，形成畸变共角MgSi₄四面体结构单元，Mg–Si键长分布范围为2.66~2.91 Å。
6. 第六种Mg²⁺位点中，Mg²⁺以三配位构型与3个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.84~3.06 Å。
7. 第七种Mg²⁺位点中，Mg²⁺以五配位构型与6个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.82~3.21 Å。
8. 第八种Mg²⁺位点中，Mg²⁺以五配位构型与5个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.68~2.85 Å。
9. 第九种Mg²⁺位点中，Mg²⁺以三配位构型与3个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.67~3.00 Å。
10. 第十种Mg²⁺位点中，Mg²⁺以畸变T型配位构型与3个Si⁺2.40⁻原子成键，Mg–Si键长包含2个较短键长（2.83 Å）与1个较长键长（2.93 Å）。
11. 第十一种Mg²⁺位点中，Mg²⁺以T型配位构型与3个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.71~2.87 Å。
12. 第十二种Mg²⁺位点中，Mg²⁺以四配位构型与4个Si⁺2.40⁻原子成键，Mg–Si键长分布范围为2.70~3.19 Å。

体系中同时存在10种不等价的Si⁺2.40⁻位点：
1. 第一种Si⁺2.40⁻位点中，Si⁺2.40⁻以七配位构型与5个Mg²⁺及2个Si⁺2.40⁻原子成键，Si–Si键长包含1个较短键长（2.42 Å）与1个较长键长（2.44 Å）。
2. 第二种Si⁺2.40⁻位点中，Si⁺2.40⁻以八配位构型与5个Mg²⁺及3个Si⁺2.40⁻原子成键，Si–Si键长包含1个较短键长（2.43 Å）与1个较长键长（2.51 Å）。
3. 第三种Si⁺2.40⁻位点中，Si⁺2.40⁻以八配位构型与6个Mg²⁺及2个Si⁺2.40⁻原子成键，Si–Si键长均为2.42 Å。
4. 第四种Si⁺2.40⁻位点中，Si⁺2.40⁻以单配位构型与3个Mg²⁺及3个Si⁺2.40⁻原子成键，Si–Si键长包含1个较短键长（2.41 Å）与1个较长键长（2.45 Å）。
5. 第五种Si⁺2.40⁻位点中，Si⁺2.40⁻以七配位构型与5个Mg²⁺及2个Si⁺2.40⁻原子成键，Si–Si键长为2.38 Å。
6. 第六种Si⁺2.40⁻位点中，Si⁺2.40⁻以七配位构型与5个Mg²⁺及2个Si⁺2.40⁻原子成键，Si–Si键长包含1个较短键长（2.40 Å）与1个较长键长（2.42 Å）。
7. 第七种Si⁺2.40⁻位点中，Si⁺2.40⁻以八配位构型与6个Mg²⁺及2个Si⁺2.40⁻原子成键。
8. 第八种Si⁺2.40⁻位点中，Si⁺2.40⁻以七配位构型与5个Mg²⁺及2个Si⁺2.40⁻原子成键。
9. 第九种Si⁺2.40⁻位点中，Si⁺2.40⁻以八配位构型与7个Mg²⁺及1个Si⁺2.40⁻原子成键。
10. 第十种Si⁺2.40⁻位点中，Si⁺2.40⁻以单配位构型与5个Mg²⁺及3个Si⁺2.40⁻原子成键。