The structure described by Ga4B2O9 crystallizes in the monoclinic C2/m space group. There are four inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(7) atoms to form GaO5 trigonal bipyramids that share corners with two equivalent Ga(2)O6 octahedra, corners with two equivalent Ga(3)O6 octahedra, corners with two equivalent Ga(4)O4 tetrahedra, and  an edgeedge with one Ga(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 51-69°. In the second Ga site, Ga(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form GaO6 octahedra that share corners with two equivalent Ga(4)O4 tetrahedra, corners with two equivalent Ga(1)O5 trigonal bipyramids, and edges with two equivalent Ga(2)O6 octahedra. In the third Ga site, Ga(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form GaO6 octahedra that share corners with two equivalent Ga(4)O4 tetrahedra, corners with two equivalent Ga(1)O5 trigonal bipyramids, and edges with two equivalent Ga(3)O6 octahedra. In the fourth Ga site, Ga(4) is bonded to one O(3), one O(7), and two equivalent O(2) atoms to form distorted GaO4 tetrahedra that share corners with two equivalent Ga(2)O6 octahedra, corners with two equivalent Ga(3)O6 octahedra, and corners with two equivalent Ga(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 57-80°. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(6) and two equivalent O(2) atoms. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(5) and two equivalent O(1) atoms. There are seven inequivalent O sites. In the first O site, O(3) is bonded in a trigonal planar geometry to one Ga(4) and two equivalent Ga(2) atoms. In the second O site, O(4) is bonded in a 3-coordinate geometry to one Ga(1) and two equivalent Ga(3) atoms. In the third O site, O(5) is bonded in a distorted T-shaped geometry to two equivalent Ga(3) and one B(2) atom. In the fourth O site, O(6) is bonded in a distorted T-shaped geometry to two equivalent Ga(2) and one B(1) atom. In the fifth O site, O(7) is bonded in a trigonal planar geometry to one Ga(4) and two equivalent Ga(1) atoms. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ga(1), one Ga(2), and one B(2) atom. In the seventh O site, O(2) is bonded in a distorted trigonal planar geometry to one Ga(3), one Ga(4), and one B(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ga4B2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.484
_cell_length_b   8.484
_cell_length_c   11.423
_cell_angle_alpha   48.902
_cell_angle_beta   48.902
_cell_angle_gamma   39.214
_symmetry_Int_Tables_number   1
_cell_volume   372.302
_cell_formula_units_Z   2
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
  Ga  Ga0  1  0.005  0.005  0.862  1.0
  Ga  Ga1  1  0.995  0.995  0.138  1.0
  Ga  Ga2  1  0.000  0.500  0.000  1.0
  Ga  Ga3  1  0.500  0.000  0.000  1.0
  Ga  Ga4  1  0.000  0.500  0.500  1.0
  Ga  Ga5  1  0.500  0.000  0.500  1.0
  Ga  Ga6  1  0.744  0.744  0.260  1.0
  Ga  Ga7  1  0.256  0.256  0.740  1.0
  B  B8  1  0.205  0.205  0.292  1.0
  B  B9  1  0.795  0.795  0.708  1.0
  B  B10  1  0.503  0.503  0.783  1.0
  B  B11  1  0.497  0.497  0.217  1.0
  O  O12  1  0.229  0.659  0.851  1.0
  O  O13  1  0.341  0.771  0.149  1.0
  O  O14  1  0.771  0.341  0.149  1.0
  O  O15  1  0.659  0.229  0.851  1.0
  O  O16  1  0.990  0.405  0.365  1.0
  O  O17  1  0.595  0.010  0.635  1.0
  O  O18  1  0.010  0.595  0.635  1.0
  O  O19  1  0.405  0.990  0.365  1.0
  O  O20  1  0.716  0.716  0.128  1.0
  O  O21  1  0.284  0.284  0.872  1.0
  O  O22  1  0.159  0.159  0.634  1.0
  O  O23  1  0.841  0.841  0.366  1.0
  O  O24  1  0.624  0.624  0.645  1.0
  O  O25  1  0.376  0.376  0.355  1.0
  O  O26  1  0.219  0.219  0.157  1.0
  O  O27  1  0.781  0.781  0.843  1.0
  O  O28  1  0.900  0.900  0.095  1.0
  O  O29  1  0.100  0.100  0.905  1.0
[/CIF]
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The structure described by Ga4B2O9 crystallizes in the monoclinic C2/m space group. There are four inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(7) atoms to form GaO5 trigonal bipyramids that share corners with two equivalent Ga(2)O6 octahedra, corners with two equivalent Ga(3)O6 octahedra, corners with two equivalent Ga(4)O4 tetrahedra, and  an edgeedge with one Ga(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 51-69°. In the second Ga site, Ga(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form GaO6 octahedra that share corners with two equivalent Ga(4)O4 tetrahedra, corners with two equivalent Ga(1)O5 trigonal bipyramids, and edges with two equivalent Ga(2)O6 octahedra. In the third Ga site, Ga(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form GaO6 octahedra that share corners with two equivalent Ga(4)O4 tetrahedra, corners with two equivalent Ga(1)O5 trigonal bipyramids, and edges with two equivalent Ga(3)O6 octahedra. In the fourth Ga site, Ga(4) is bonded to one O(3), one O(7), and two equivalent O(2) atoms to form distorted GaO4 tetrahedra that share corners with two equivalent Ga(2)O6 octahedra, corners with two equivalent Ga(3)O6 octahedra, and corners with two equivalent Ga(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 57-80°. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(6) and two equivalent O(2) atoms. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(5) and two equivalent O(1) atoms. There are seven inequivalent O sites. In the first O site, O(3) is bonded in a trigonal planar geometry to one Ga(4) and two equivalent Ga(2) atoms. In the second O site, O(4) is bonded in a 3-coordinate geometry to one Ga(1) and two equivalent Ga(3) atoms. In the third O site, O(5) is bonded in a distorted T-shaped geometry to two equivalent Ga(3) and one B(2) atom. In the fourth O site, O(6) is bonded in a distorted T-shaped geometry to two equivalent Ga(2) and one B(1) atom. In the fifth O site, O(7) is bonded in a trigonal planar geometry to one Ga(4) and two equivalent Ga(1) atoms. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ga(1), one Ga(2), and one B(2) atom. In the seventh O site, O(2) is bonded in a distorted trigonal planar geometry to one Ga(3), one Ga(4), and one B(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ga4B2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.484
_cell_length_b   8.484
_cell_length_c   11.423
_cell_angle_alpha   48.902
_cell_angle_beta   48.902
_cell_angle_gamma   39.214
_symmetry_Int_Tables_number   1
_cell_volume   372.302
_cell_formula_units_Z   2
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
  Ga  Ga0  1  0.005  0.005  0.862  1.0
  Ga  Ga1  1  0.995  0.995  0.138  1.0
  Ga  Ga2  1  0.000  0.500  0.000  1.0
  Ga  Ga3  1  0.500  0.000  0.000  1.0
  Ga  Ga4  1  0.000  0.500  0.500  1.0
  Ga  Ga5  1  0.500  0.000  0.500  1.0
  Ga  Ga6  1  0.744  0.744  0.260  1.0
  Ga  Ga7  1  0.256  0.256  0.740  1.0
  B  B8  1  0.205  0.205  0.292  1.0
  B  B9  1  0.795  0.795  0.708  1.0
  B  B10  1  0.503  0.503  0.783  1.0
  B  B11  1  0.497  0.497  0.217  1.0
  O  O12  1  0.229  0.659  0.851  1.0
  O  O13  1  0.341  0.771  0.149  1.0
  O  O14  1  0.771  0.341  0.149  1.0
  O  O15  1  0.659  0.229  0.851  1.0
  O  O16  1  0.990  0.405  0.365  1.0
  O  O17  1  0.595  0.010  0.635  1.0
  O  O18  1  0.010  0.595  0.635  1.0
  O  O19  1  0.405  0.990  0.365  1.0
  O  O20  1  0.716  0.716  0.128  1.0
  O  O21  1  0.284  0.284  0.872  1.0
  O  O22  1  0.159  0.159  0.634  1.0
  O  O23  1  0.841  0.841  0.366  1.0
  O  O24  1  0.624  0.624  0.645  1.0
  O  O25  1  0.376  0.376  0.355  1.0
  O  O26  1  0.219  0.219  0.157  1.0
  O  O27  1  0.781  0.781  0.843  1.0
  O  O28  1  0.900  0.900  0.095  1.0
  O  O29  1  0.100  0.100  0.905  1.0
[/CIF]
.