The compound Na-2[(UO2)(2)(SeO4)(3)(H2O)(2)] center dot 6.5H(2)O (I) is studied using X-ray diffraction. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 19.7366(8) angstrom, b = 10.8206(4) angstrom, c = 21.3577(8) angstrom, beta = 103.4311(1)degrees, Z = 4, and the space group P2(1)/c, R-1 = 0.0379. Compound I is found to be a representative of the crystal-chemical group A(2)T(2)(3)B(2)M(2)(1) (A = UO22+) of uranyl complexes and contains the cage group [(UO2)(2)(SeO4)(3)(H2O)(2)](2-).

The compound Na 2 [(UO 2 ) 2 (SeO 4 ) 3 (H 2 O) 2 ] · 6.5H 2 O ( I ) is studied using X-ray diffraction. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 19.7366(8) Å, b = 10.8206(4) Å, c = 21.3577(8) Å, β = 103.4311(1)°, Z = 4, and the space group P 2 1 / c , R 1 = 0.0379. Compound I is found to be a representative of the crystal-chemical group A 2 T 2 3 B 2 M 2 1 (A = UO 2 2+ ) of uranyl complexes and contains the cage group [(UO 2 ) 2 (SeO 4 ) 3 (H 2 O) 2 ] 2− .

The complex Na-6[(UO2)(3)O(OH)(3)(SeO4)(2)](2) center dot 10H(2)O (I) is synthesized and studied by X-ray diffraction. The compound crystallizes in the orthorhombic crystal system with the unit cell parameters: a = 14.2225(7) angstrom, b = 18.3601(7) angstrom, c = 16.5406(6) angstrom, V = 4319.2(3) angstrom(3), Z = 4, space group Cmcm, R-1 = 0.0406. Compound I is found to be a representative of the crystal-chemical group A(3)M(3)M(3)(2)T(2)(3) (A = UO22+, M-3 = O2-, M-2 = OH-, T-3 = SeO42-) of the uranyl complexes; it contains layer uranium-containing groups [(UO2)(3)O(OH)(3)(SeO4)(2)](3-). These layers linked to form a three-dimensional cage through bonds formed by the sodium atoms with the oxygen atoms of the uranyl ions and SeO4 groups that belong to different layers.

The complex Na 6 [(UO 2 ) 3 O(OH) 3 (SeO 4 ) 2 ] 2 · 10H 2 O ( I ) is synthesized and studied by X-ray diffraction. The compound crystallizes in the orthorhombic crystal system with the unit cell parameters: a = 14.2225(7) Å, b = 18.3601(7) Å, c = 16.5406(6) Å, V = 4319.2(3) Å 3 , Z = 4, space group Cmcm , R 1 = 0.0406. Compound I is found to be a representative of the crystal-chemical group A 3 M 3 M 2 3 T 3 2 (A = UO 2+ 2 , M 3 = O 2− , M 2 = OH − , T 3 = SeO 2− 4 ) of the uranyl complexes; it contains layer uranium-containing groups [(UO 2 ) 3 O(OH) 3 (SeO 4 ) 2 ] 3− . These layers linked to form a three-dimensional cage through bonds formed by the sodium atoms with the oxygen atoms of the uranyl ions and SeO 4 groups that belong to different layers.

The crystals structure of Na-2(UO2)(4)(C2O4)(5) . 10H(2)O (I) was determined by X-ray diffraction. Crystals of I are triclinic: space group P (1) over bar, Z = 1, a = 5.585 Angstrom, b = 11.359 Angstrom, c = 14.624 Angstrom, alpha = 98.03degrees, beta = 99.00degrees, gamma = 103.86degrees, V = 874.3 Angstrom(3). The basic structural unit in crystals of I is a [(UO2)(4)(C2O4)(5)(H2O)(2)](2-) layer belonging to the crystal-chemical group A(4)K(2)(02)M(2)(1) (A = UO22+) of uranyl complexes and consisting of ten-membered metallacycles including alternating uranyl and oxalate ions. The layers are combined in a three-dimensional framework {Na(H-2)(3)}(2)[(UO2)(4)(C2O4)(5)(H2O)(2)] by the bonds involving sodium atoms and uranyl and oxalate oxygen atoms from different layers. Compound I, with a zeolite-type structure, is the first example of oxalato-uranylates in which U(IV) atoms with different CNs (7 and 8) coexist.

The crystals structure of Na 2 (UO 2 ) 4 (C 2 O 4 ) 5 .10H 2 O (I) was determined by X-ray diffraction. Crystals of I are triclinic: space group P1, Z = 1, a = 5.585 A, b = 11.359 A, c = 14.624 A, a = 98.03°, β = 99.00°, y= 103.86°, V = 874.3 A 3 . The basic structural unit in crystals of I is a [(UO 2 ) 4 (C 2 O 4 ) 5 (H 2 O) 2 ] 2 - layer belonging to the crystal-chemical group A 4 K 2 02M 1 2 (A = UO 2 + 2) of uranyl complexes and consisting of ten-membered metallacycles including alternating uranyl and oxalate ions. The layers are combined in a three-dimensional framework (Na(H 2 ) 2 } 2 [(UO 2 ) 4 (C 2 O 4 ) 5 (H 2 O) 2 ] by the bonds involving sodium atoms and uranyl and oxalate oxygen atoms from different layers. Compound I, with a zeolite-type structure, is the first example of oxalatouranylates in which U(IV) atoms with different CNs (7 and 8) coexist.

The X-ray single-crystal structure experiment was carried out for Na2UO2(C2O4)(2) . 5H(2)O (compound I). The crystals of compound I are triclinic, space group P1, Z = 2, unit cell parameters a = 6.938 Angstrom, b = 7.566 Angstrom, c = 15.409 Angstrom, alpha = 94.76degrees, beta = 96.38degrees, gamma = 111.67degrees. The basic structural units of the crystals of compound I are [UO2(C2O4)(2)(H2O)](2-) mononuclear uranium complexes, which belong to the A B-2(01) M-1 (A=UO22+) crystallochemical family of uranyl complexes. The complexes are constituents of [Na[UO2(C2O4)(2)(H2O). H2O](-) layers, which arise due to linking of sodium atoms and the oxalato or uranyl oxygen atoms. The remaining sodium ions and water molecules are positioned between layers pairing up layers, to form electroneutral double stacks.

The X-ray single-crystal structure experiment was carried out for Na 2 UO 2 (C 2 O 4 ) 2 .5H 2 O (compound I). The crystals of compound I are triclinic, space group P1, Z = 2, unit cell parameters a = 6.938 A, b = 7.566 A, c = 15.409 A, α = 94.76°, β = 96.38°, y= 111.67°. The basic structural units of the crystals of compound I are [UO 2 (C 2 O 4 ) 2 (H 2 O)] 2 - mononuclear uranium complexes, which belong to the AB 0 1 2 M 1 (A = UO 2 + 2 ) crystallochemical family of uranyl complexes. The complexes are constituents of {Na[UO 2 (C 2 O 4 ) 2 (H 2 O)]. H 2 O} - layers, which arise due to linking of sodium atoms and the oxalato or uranyl oxygen atoms. The remaining sodium ions and water molecules are positioned between layers pairing up layers, to form electroneutral double stacks.

The Na-2[UO2(SeO4)(2)] . 4H(2)O compound (I), formed in the Na2SeO4-UO2SeO4-H2O System at 25degreesC, was studied by X-ray crystallography. Crystals of I are monoclinic: a = 8.650 Angstrom, b = 11.003 Angstrom, c = 13.879 Angstrom, beta = 108.08degrees, Z = 4, space group P2(1)/c, R = 0.031. Compound I is representative of the crystal-chemical group AT(3)B(2) (A=UO22+) of uranyl complexes. It has a layered structure consisting [UO2(SeO4)(2)](2-) entities. The sodium ions and water molecules coordinated to them are located in the interlayers.

The Na 2 [UO 2 (SeO 4 ) 2 ] 4H 2 O compound (I), formed in the Na 2 SeO 4 -UO 2 SeO 4 -H 2 O system at 25°C, was studied by X-ray crystallography. Crystals of I are monoclinic: a = 8.650 A, b = 11.003 A, c = 13.879 A, β = 108.08°, Z = 4, space group P2 1 /c, R = 0.031. Compound I is representative of the crystal-chemical group AT 3 B 2 (A = UO 2 + 2 ) of uranyl complexes. It has a layered structure consisting of [UO 2 (SeO 4 ) 2 ] 2 - entities. The sodium ions and water molecules coordinated to them are located in the interlayers.