Materials Data on Na2P2H2O7 by Materials Project

H2P2O7Na2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.39–2.80 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.37–2.81 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.38–2.80 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.38–2.81 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.40–2.81 Å. In the sixth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.38–2.81 Å. In the seventh Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.41–2.82 Å. In the eighth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six PO4 tetrahedra and edges with four NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.41–2.82 Å. There are eight inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–63°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–63°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–62°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–64°. There are a spread of P–O bond distances ranging from 1.51–1.63 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–61°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–63°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–62°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six NaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–63°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.20 Å) and one longer (1.21 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.17 Å) and one longer (1.24 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.20 Å) and one longer (1.21 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.18 Å) and one longer (1.23 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.20 Å) and one longer (1.22 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.20 Å) and one longer (1.21 Å) H–O bond length. In the seventh H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.19 Å) and one longer (1.23 Å) H–O bond length. In the eighth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.18 Å) and one longer (1.24 Å) H–O bond length. There are twenty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one P5+, and one H1+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one P5+, and one H1+ atom. In the seventeenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the twentieth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twenty-sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twenty-seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twenty-eighth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms.

二氢二磷酸二钠（H₂P₂O₇Na₂）结晶于三斜晶系P1空间群（triclinic P1 space group），其结构为三维框架结构。
体系内存在8个不等价的Na⁺（Na1+）占位位点。在首个Na⁺占位位点中，Na⁺与6个O²⁻（O2-）配位形成畸变NaO₆八面体（NaO6 octahedra），该八面体与6个PO₄四面体（PO4 tetrahedra）共享顶点，同时与4个NaO₆八面体共享棱边，Na–O键长分布范围为2.39~2.80 Å。在第二个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.37~2.81 Å。在第三个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.38~2.80 Å。在第四个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.38~2.81 Å。在第五个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.40~2.81 Å。在第六个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.38~2.81 Å。在第七个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.41~2.82 Å。在第八个Na⁺占位位点中，Na⁺与6个O²⁻配位形成畸变NaO₆八面体，该八面体与6个PO₄四面体共享顶点、与4个NaO₆八面体共享棱边，Na–O键长范围为2.41~2.82 Å。
体系内存在8个不等价的P⁵+（P5+）占位位点。在首个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点，同时与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~63°，P–O键长分布范围为1.51~1.62 Å。在第二个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~63°，P–O键长范围为1.51~1.62 Å。在第三个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~62°，P–O键长范围为1.51~1.62 Å。在第四个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~64°，P–O键长范围为1.51~1.63 Å。在第五个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~61°，P–O键长范围为1.51~1.62 Å。在第六个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~63°，P–O键长范围为1.51~1.62 Å。在第七个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~62°，P–O键长范围为1.51~1.62 Å。在第八个P⁵+占位位点中，P⁵+与4个O²⁻配位形成PO₄四面体，该四面体与6个NaO₆八面体共享顶点、与1个PO₄四面体共享顶点，八面体倾斜角范围为52°~63°，P–O键长范围为1.51~1.62 Å。
体系内存在8个不等价的H⁺（H1+）占位位点。在首个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键存在1个较短键长（1.20 Å）与1个较长键长（1.21 Å）。在第二个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.17 Å与1.24 Å。在第三个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.20 Å与1.21 Å。在第四个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.18 Å与1.23 Å。在第五个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.20 Å与1.22 Å。在第六个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.20 Å与1.21 Å。在第七个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.19 Å与1.23 Å。在第八个H⁺占位位点中，H⁺以线性几何构型与2个O²⁻配位，H–O键长分别为1.18 Å与1.24 Å。
体系内存在28个不等价的O²⁻（O2-）占位位点。前7个O²⁻占位位点均以畸变三角平面几何构型，分别与1个Na⁺、1个P⁵+及1个H⁺成键。第八个O²⁻占位位点以三配位几何构型，分别与1个Na⁺、1个P⁵+及1个H⁺成键。第九至第十六个O²⁻占位位点均以双配位几何构型，分别与2个Na⁺、1个P⁵+及1个H⁺成键。第十七至第二十四个O²⁻占位位点均以畸变矩形跷跷板型几何构型，分别与3个Na⁺及1个P⁵+成键。第二十五至第二十八个O²⁻占位位点均以120°弯折几何构型，分别与2个P⁵+成键。