The structure described by Ca2As3 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2/c space group. There are five inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one As(1), one As(3), one As(5), two equivalent As(6), and three equivalent As(2) atoms. In the second Ca site, Ca(2) is bonded to one As(1), one As(2), one As(3), two equivalent As(4), and three equivalent As(5) atoms to form a mixture of distorted face, corner, and edge-sharing CaAs8 hexagonal bipyramids. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one As(2), one As(3), one As(5), two equivalent As(1), two equivalent As(4), and two equivalent As(6) atoms. In the fourth Ca site, Ca(4) is bonded in a 8-coordinate geometry to two equivalent As(2), two equivalent As(4), and four equivalent As(1) atoms. In the fifth Ca site, Ca(5) is bonded in a 8-coordinate geometry to two equivalent As(4), two equivalent As(5), two equivalent As(6), and four equivalent As(3) atoms. There are six inequivalent As sites. In the first As site, As(5) is bonded in a 7-coordinate geometry to one Ca(1), one Ca(3), one Ca(5), three equivalent Ca(2), and one As(4) atom. In the second As site, As(6) is bonded in a 7-coordinate geometry to one Ca(5), two equivalent Ca(1), two equivalent Ca(3), one As(3), and one As(4) atom. In the third As site, As(1) is bonded in a 8-coordinate geometry to one Ca(1), one Ca(2), two equivalent Ca(3), two equivalent Ca(4), one As(1), and one As(2) atom. In the fourth As site, As(2) is bonded in a 7-coordinate geometry to one Ca(2), one Ca(3), one Ca(4), three equivalent Ca(1), and one As(1) atom. In the fifth As site, As(3) is bonded in a 7-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), two equivalent Ca(5), one As(3), and one As(6) atom. In the sixth As site, As(4) is bonded in a 8-coordinate geometry to one Ca(4), one Ca(5), two equivalent Ca(2), two equivalent Ca(3), one As(5), and one As(6) atom. is represented by the CIF card [CIF]
data_Ca2As3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.836
_cell_length_b   12.014
_cell_length_c   13.781
_cell_angle_alpha   90.973
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   966.157
_cell_formula_units_Z   8
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
  Ca  Ca0  1  0.755  0.625  0.000  1.0
  Ca  Ca1  1  0.755  0.875  0.500  1.0
  Ca  Ca2  1  0.245  0.375  1.000  1.0
  Ca  Ca3  1  0.245  0.125  0.500  1.0
  Ca  Ca4  1  0.738  0.375  0.511  1.0
  Ca  Ca5  1  0.738  0.125  0.989  1.0
  Ca  Ca6  1  0.262  0.625  0.489  1.0
  Ca  Ca7  1  0.262  0.875  0.011  1.0
  Ca  Ca8  1  0.453  0.991  0.752  1.0
  Ca  Ca9  1  0.453  0.509  0.748  1.0
  Ca  Ca10  1  0.547  0.009  0.248  1.0
  Ca  Ca11  1  0.547  0.491  0.252  1.0
  Ca  Ca12  1  0.035  0.750  0.750  1.0
  Ca  Ca13  1  0.965  0.250  0.250  1.0
  Ca  Ca14  1  0.096  0.250  0.750  1.0
  Ca  Ca15  1  0.904  0.750  0.250  1.0
  As  As16  1  0.457  0.234  0.159  1.0
  As  As17  1  0.457  0.266  0.341  1.0
  As  As18  1  0.543  0.766  0.841  1.0
  As  As19  1  0.543  0.734  0.659  1.0
  As  As20  1  0.270  0.862  0.579  1.0
  As  As21  1  0.270  0.638  0.921  1.0
  As  As22  1  0.730  0.138  0.421  1.0
  As  As23  1  0.730  0.362  0.079  1.0
  As  As24  1  0.605  0.288  0.834  1.0
  As  As25  1  0.605  0.212  0.666  1.0
  As  As26  1  0.395  0.712  0.166  1.0
  As  As27  1  0.395  0.788  0.334  1.0
  As  As28  1  0.951  0.512  0.673  1.0
  As  As29  1  0.951  0.988  0.827  1.0
  As  As30  1  0.049  0.488  0.327  1.0
  As  As31  1  0.049  0.012  0.173  1.0
  As  As32  1  0.778  0.891  0.079  1.0
  As  As33  1  0.778  0.609  0.421  1.0
  As  As34  1  0.222  0.109  0.921  1.0
  As  As35  1  0.222  0.391  0.579  1.0
  As  As36  1  0.900  0.448  0.844  1.0
  As  As37  1  0.900  0.052  0.656  1.0
  As  As38  1  0.100  0.552  0.156  1.0
  As  As39  1  0.100  0.948  0.344  1.0
[/CIF]
.
The structure described by Ca2As3 is Magnesium tetraboride-like structured and crystallizes in the monoclinic P2/c space group. There are five inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one As(1), one As(3), one As(5), two equivalent As(6), and three equivalent As(2) atoms. In the second Ca site, Ca(2) is bonded to one As(1), one As(2), one As(3), two equivalent As(4), and three equivalent As(5) atoms to form a mixture of distorted face, corner, and edge-sharing CaAs8 hexagonal bipyramids. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one As(2), one As(3), one As(5), two equivalent As(1), two equivalent As(4), and two equivalent As(6) atoms. In the fourth Ca site, Ca(4) is bonded in a 8-coordinate geometry to two equivalent As(2), two equivalent As(4), and four equivalent As(1) atoms. In the fifth Ca site, Ca(5) is bonded in a 8-coordinate geometry to two equivalent As(4), two equivalent As(5), two equivalent As(6), and four equivalent As(3) atoms. There are six inequivalent As sites. In the first As site, As(5) is bonded in a 7-coordinate geometry to one Ca(1), one Ca(3), one Ca(5), three equivalent Ca(2), and one As(4) atom. In the second As site, As(6) is bonded in a 7-coordinate geometry to one Ca(5), two equivalent Ca(1), two equivalent Ca(3), one As(3), and one As(4) atom. In the third As site, As(1) is bonded in a 8-coordinate geometry to one Ca(1), one Ca(2), two equivalent Ca(3), two equivalent Ca(4), one As(1), and one As(2) atom. In the fourth As site, As(2) is bonded in a 7-coordinate geometry to one Ca(2), one Ca(3), one Ca(4), three equivalent Ca(1), and one As(1) atom. In the fifth As site, As(3) is bonded in a 7-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), two equivalent Ca(5), one As(3), and one As(6) atom. In the sixth As site, As(4) is bonded in a 8-coordinate geometry to one Ca(4), one Ca(5), two equivalent Ca(2), two equivalent Ca(3), one As(5), and one As(6) atom. is represented by the CIF card [CIF]
data_Ca2As3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.836
_cell_length_b   12.014
_cell_length_c   13.781
_cell_angle_alpha   90.973
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   966.157
_cell_formula_units_Z   8
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
  Ca  Ca0  1  0.755  0.625  0.000  1.0
  Ca  Ca1  1  0.755  0.875  0.500  1.0
  Ca  Ca2  1  0.245  0.375  1.000  1.0
  Ca  Ca3  1  0.245  0.125  0.500  1.0
  Ca  Ca4  1  0.738  0.375  0.511  1.0
  Ca  Ca5  1  0.738  0.125  0.989  1.0
  Ca  Ca6  1  0.262  0.625  0.489  1.0
  Ca  Ca7  1  0.262  0.875  0.011  1.0
  Ca  Ca8  1  0.453  0.991  0.752  1.0
  Ca  Ca9  1  0.453  0.509  0.748  1.0
  Ca  Ca10  1  0.547  0.009  0.248  1.0
  Ca  Ca11  1  0.547  0.491  0.252  1.0
  Ca  Ca12  1  0.035  0.750  0.750  1.0
  Ca  Ca13  1  0.965  0.250  0.250  1.0
  Ca  Ca14  1  0.096  0.250  0.750  1.0
  Ca  Ca15  1  0.904  0.750  0.250  1.0
  As  As16  1  0.457  0.234  0.159  1.0
  As  As17  1  0.457  0.266  0.341  1.0
  As  As18  1  0.543  0.766  0.841  1.0
  As  As19  1  0.543  0.734  0.659  1.0
  As  As20  1  0.270  0.862  0.579  1.0
  As  As21  1  0.270  0.638  0.921  1.0
  As  As22  1  0.730  0.138  0.421  1.0
  As  As23  1  0.730  0.362  0.079  1.0
  As  As24  1  0.605  0.288  0.834  1.0
  As  As25  1  0.605  0.212  0.666  1.0
  As  As26  1  0.395  0.712  0.166  1.0
  As  As27  1  0.395  0.788  0.334  1.0
  As  As28  1  0.951  0.512  0.673  1.0
  As  As29  1  0.951  0.988  0.827  1.0
  As  As30  1  0.049  0.488  0.327  1.0
  As  As31  1  0.049  0.012  0.173  1.0
  As  As32  1  0.778  0.891  0.079  1.0
  As  As33  1  0.778  0.609  0.421  1.0
  As  As34  1  0.222  0.109  0.921  1.0
  As  As35  1  0.222  0.391  0.579  1.0
  As  As36  1  0.900  0.448  0.844  1.0
  As  As37  1  0.900  0.052  0.656  1.0
  As  As38  1  0.100  0.552  0.156  1.0
  As  As39  1  0.100  0.948  0.344  1.0
[/CIF]
.