The compound described by PbGe4O9 crystallizes in the trigonal P321 space group. Pb(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(4) atoms. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(3)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra, and  a cornercorner with one Ge(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-61°. In the second Ge site, Ge(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form GeO4 tetrahedra that share corners with two equivalent Ge(4)O6 octahedra and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 62°. In the third Ge site, Ge(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form corner-sharing GeO6 octahedra. In the fourth Ge site, Ge(4) is bonded to six equivalent O(1) atoms to form corner-sharing GeO6 octahedra. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Pb(1), one Ge(1), and one Ge(3) atom. In the second O site, O(5) is bonded in a bent 120 degrees geometry to two equivalent Ge(1) atoms. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Pb(1), one Ge(2), and one Ge(4) atom. In the fourth O site, O(2) is bonded in a bent 120 degrees geometry to one Ge(1) and one Ge(2) atom. In the fifth O site, O(3) is bonded in a bent 120 degrees geometry to one Ge(1) and one Ge(3) atom. is represented by the CIF file [CIF]
data_Ge4PbO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.559
_cell_length_b   11.559
_cell_length_c   4.829
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   558.717
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ge  Ge0  1  0.149  0.491  0.398  1.0
  Ge  Ge1  1  0.509  0.659  0.398  1.0
  Ge  Ge2  1  0.341  0.851  0.398  1.0
  Ge  Ge3  1  0.659  0.509  0.602  1.0
  Ge  Ge4  1  0.851  0.341  0.602  1.0
  Ge  Ge5  1  0.491  0.149  0.602  1.0
  Ge  Ge6  1  0.180  0.000  0.500  1.0
  Ge  Ge7  1  0.000  0.180  0.500  1.0
  Ge  Ge8  1  0.820  0.820  0.500  1.0
  Ge  Ge9  1  0.333  0.667  0.888  1.0
  Ge  Ge10  1  0.667  0.333  0.112  1.0
  Ge  Ge11  1  0.000  0.000  0.000  1.0
  Pb  Pb12  1  0.674  0.000  0.000  1.0
  Pb  Pb13  1  0.000  0.674  0.000  1.0
  Pb  Pb14  1  0.326  0.326  0.000  1.0
  O  O15  1  0.094  0.154  0.762  1.0
  O  O16  1  0.846  0.939  0.762  1.0
  O  O17  1  0.061  0.906  0.762  1.0
  O  O18  1  0.939  0.846  0.238  1.0
  O  O19  1  0.906  0.061  0.238  1.0
  O  O20  1  0.154  0.094  0.238  1.0
  O  O21  1  0.109  0.325  0.293  1.0
  O  O22  1  0.675  0.784  0.293  1.0
  O  O23  1  0.216  0.891  0.293  1.0
  O  O24  1  0.784  0.675  0.707  1.0
  O  O25  1  0.891  0.216  0.707  1.0
  O  O26  1  0.325  0.109  0.707  1.0
  O  O27  1  0.262  0.511  0.666  1.0
  O  O28  1  0.489  0.751  0.666  1.0
  O  O29  1  0.249  0.738  0.666  1.0
  O  O30  1  0.751  0.489  0.334  1.0
  O  O31  1  0.738  0.249  0.334  1.0
  O  O32  1  0.511  0.262  0.334  1.0
  O  O33  1  0.180  0.601  0.118  1.0
  O  O34  1  0.399  0.579  0.118  1.0
  O  O35  1  0.421  0.820  0.118  1.0
  O  O36  1  0.579  0.399  0.882  1.0
  O  O37  1  0.820  0.421  0.882  1.0
  O  O38  1  0.601  0.180  0.882  1.0
  O  O39  1  0.488  0.000  0.500  1.0
  O  O40  1  0.000  0.488  0.500  1.0
  O  O41  1  0.512  0.512  0.500  1.0
[/CIF]
.
The compound described by PbGe4O9 crystallizes in the trigonal P321 space group. Pb(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(4) atoms. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form GeO4 tetrahedra that share corners with two equivalent Ge(3)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra, and  a cornercorner with one Ge(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-61°. In the second Ge site, Ge(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form GeO4 tetrahedra that share corners with two equivalent Ge(4)O6 octahedra and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 62°. In the third Ge site, Ge(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form corner-sharing GeO6 octahedra. In the fourth Ge site, Ge(4) is bonded to six equivalent O(1) atoms to form corner-sharing GeO6 octahedra. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Pb(1), one Ge(1), and one Ge(3) atom. In the second O site, O(5) is bonded in a bent 120 degrees geometry to two equivalent Ge(1) atoms. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Pb(1), one Ge(2), and one Ge(4) atom. In the fourth O site, O(2) is bonded in a bent 120 degrees geometry to one Ge(1) and one Ge(2) atom. In the fifth O site, O(3) is bonded in a bent 120 degrees geometry to one Ge(1) and one Ge(3) atom. is represented by the CIF file [CIF]
data_Ge4PbO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.559
_cell_length_b   11.559
_cell_length_c   4.829
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   558.717
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ge  Ge0  1  0.149  0.491  0.398  1.0
  Ge  Ge1  1  0.509  0.659  0.398  1.0
  Ge  Ge2  1  0.341  0.851  0.398  1.0
  Ge  Ge3  1  0.659  0.509  0.602  1.0
  Ge  Ge4  1  0.851  0.341  0.602  1.0
  Ge  Ge5  1  0.491  0.149  0.602  1.0
  Ge  Ge6  1  0.180  0.000  0.500  1.0
  Ge  Ge7  1  0.000  0.180  0.500  1.0
  Ge  Ge8  1  0.820  0.820  0.500  1.0
  Ge  Ge9  1  0.333  0.667  0.888  1.0
  Ge  Ge10  1  0.667  0.333  0.112  1.0
  Ge  Ge11  1  0.000  0.000  0.000  1.0
  Pb  Pb12  1  0.674  0.000  0.000  1.0
  Pb  Pb13  1  0.000  0.674  0.000  1.0
  Pb  Pb14  1  0.326  0.326  0.000  1.0
  O  O15  1  0.094  0.154  0.762  1.0
  O  O16  1  0.846  0.939  0.762  1.0
  O  O17  1  0.061  0.906  0.762  1.0
  O  O18  1  0.939  0.846  0.238  1.0
  O  O19  1  0.906  0.061  0.238  1.0
  O  O20  1  0.154  0.094  0.238  1.0
  O  O21  1  0.109  0.325  0.293  1.0
  O  O22  1  0.675  0.784  0.293  1.0
  O  O23  1  0.216  0.891  0.293  1.0
  O  O24  1  0.784  0.675  0.707  1.0
  O  O25  1  0.891  0.216  0.707  1.0
  O  O26  1  0.325  0.109  0.707  1.0
  O  O27  1  0.262  0.511  0.666  1.0
  O  O28  1  0.489  0.751  0.666  1.0
  O  O29  1  0.249  0.738  0.666  1.0
  O  O30  1  0.751  0.489  0.334  1.0
  O  O31  1  0.738  0.249  0.334  1.0
  O  O32  1  0.511  0.262  0.334  1.0
  O  O33  1  0.180  0.601  0.118  1.0
  O  O34  1  0.399  0.579  0.118  1.0
  O  O35  1  0.421  0.820  0.118  1.0
  O  O36  1  0.579  0.399  0.882  1.0
  O  O37  1  0.820  0.421  0.882  1.0
  O  O38  1  0.601  0.180  0.882  1.0
  O  O39  1  0.488  0.000  0.500  1.0
  O  O40  1  0.000  0.488  0.500  1.0
  O  O41  1  0.512  0.512  0.500  1.0
[/CIF]
.