The crystal structure described by Pt3Nb is beta Cu3Ti-like structured and crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one Pt(1), two equivalent Pt(4), three equivalent Pt(2), and six equivalent Pt(3) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(2)Pt12 cuboctahedra, corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. In the second Nb site, Nb(2) is bonded to one Pt(2), two equivalent Pt(3), three equivalent Pt(1), and six equivalent Pt(4) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(1)Pt12 cuboctahedra, corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(2)Pt12 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with four equivalent Pt(1)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. There are four inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Nb(1), three equivalent Nb(2), two equivalent Pt(3), and six equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with four equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. In the second Pt site, Pt(2) is bonded in a distorted see-saw-like geometry to one Nb(2), three equivalent Nb(1), two equivalent Pt(4), and six equivalent Pt(3) atoms. In the third Pt site, Pt(3) is bonded to one Nb(2), three equivalent Nb(1), one Pt(1), one Pt(4), three equivalent Pt(2), and three equivalent Pt(3) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with five equivalent Pt(4)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with three equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with three equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Pt(3)Nb4Pt8 cuboctahedra,  a faceface with one Nb(2)Pt12 cuboctahedra,  a faceface with one Pt(1)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with five equivalent Pt(4)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. In the fourth Pt site, Pt(4) is bonded to one Nb(1), three equivalent Nb(2), one Pt(2), one Pt(3), three equivalent Pt(1), and three equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with five equivalent Pt(3)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with three equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(4)Nb4Pt8 cuboctahedra,  a faceface with one Nb(1)Pt12 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, faces with three equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with five equivalent Pt(3)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_NbPt3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.908
_cell_length_b   5.582
_cell_length_c   9.370
_cell_angle_alpha   90.000
_cell_angle_beta   100.654
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   252.252
_cell_formula_units_Z   4
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
  Nb  Nb0  1  0.620  0.250  0.378  1.0
  Nb  Nb1  1  0.380  0.750  0.622  1.0
  Nb  Nb2  1  0.787  0.250  0.872  1.0
  Nb  Nb3  1  0.213  0.750  0.128  1.0
  Pt  Pt4  1  0.207  0.250  0.128  1.0
  Pt  Pt5  1  0.793  0.750  0.872  1.0
  Pt  Pt6  1  0.391  0.250  0.625  1.0
  Pt  Pt7  1  0.609  0.750  0.375  1.0
  Pt  Pt8  1  0.119  0.001  0.374  1.0
  Pt  Pt9  1  0.881  0.501  0.626  1.0
  Pt  Pt10  1  0.881  0.999  0.626  1.0
  Pt  Pt11  1  0.119  0.499  0.374  1.0
  Pt  Pt12  1  0.708  0.002  0.123  1.0
  Pt  Pt13  1  0.292  0.502  0.877  1.0
  Pt  Pt14  1  0.292  0.998  0.877  1.0
  Pt  Pt15  1  0.708  0.498  0.123  1.0
[/CIF]
.
The crystal structure described by Pt3Nb is beta Cu3Ti-like structured and crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one Pt(1), two equivalent Pt(4), three equivalent Pt(2), and six equivalent Pt(3) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(2)Pt12 cuboctahedra, corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. In the second Nb site, Nb(2) is bonded to one Pt(2), two equivalent Pt(3), three equivalent Pt(1), and six equivalent Pt(4) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(1)Pt12 cuboctahedra, corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(2)Pt12 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with four equivalent Pt(1)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. There are four inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Nb(1), three equivalent Nb(2), two equivalent Pt(3), and six equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with four equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. In the second Pt site, Pt(2) is bonded in a distorted see-saw-like geometry to one Nb(2), three equivalent Nb(1), two equivalent Pt(4), and six equivalent Pt(3) atoms. In the third Pt site, Pt(3) is bonded to one Nb(2), three equivalent Nb(1), one Pt(1), one Pt(4), three equivalent Pt(2), and three equivalent Pt(3) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with five equivalent Pt(4)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with three equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with three equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Pt(3)Nb4Pt8 cuboctahedra,  a faceface with one Nb(2)Pt12 cuboctahedra,  a faceface with one Pt(1)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with five equivalent Pt(4)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. In the fourth Pt site, Pt(4) is bonded to one Nb(1), three equivalent Nb(2), one Pt(2), one Pt(3), three equivalent Pt(1), and three equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with five equivalent Pt(3)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with three equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(4)Nb4Pt8 cuboctahedra,  a faceface with one Nb(1)Pt12 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, faces with three equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with five equivalent Pt(3)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_NbPt3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.908
_cell_length_b   5.582
_cell_length_c   9.370
_cell_angle_alpha   90.000
_cell_angle_beta   100.654
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   252.252
_cell_formula_units_Z   4
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
  Nb  Nb0  1  0.620  0.250  0.378  1.0
  Nb  Nb1  1  0.380  0.750  0.622  1.0
  Nb  Nb2  1  0.787  0.250  0.872  1.0
  Nb  Nb3  1  0.213  0.750  0.128  1.0
  Pt  Pt4  1  0.207  0.250  0.128  1.0
  Pt  Pt5  1  0.793  0.750  0.872  1.0
  Pt  Pt6  1  0.391  0.250  0.625  1.0
  Pt  Pt7  1  0.609  0.750  0.375  1.0
  Pt  Pt8  1  0.119  0.001  0.374  1.0
  Pt  Pt9  1  0.881  0.501  0.626  1.0
  Pt  Pt10  1  0.881  0.999  0.626  1.0
  Pt  Pt11  1  0.119  0.499  0.374  1.0
  Pt  Pt12  1  0.708  0.002  0.123  1.0
  Pt  Pt13  1  0.292  0.502  0.877  1.0
  Pt  Pt14  1  0.292  0.998  0.877  1.0
  Pt  Pt15  1  0.708  0.498  0.123  1.0
[/CIF]
.