N. N. Golovnev

Calcium and strontium thiobarbiturates with discrete and polymeric structures

Three new alkaline earth metal complexes, [Ca2(H2O)8(μ2-HTBA-O,O′)2(HTBA-O)2] (1), [Ca(H2O)5(HTBA-O)2]·2H2O (2), and [Sr(H2O)4(μ2-HTBA-O,S)2]n (3) (H2TBA = 2-thiobarbituric acid, C4H4N2O2S), were synthesized and characterized by FT-IR spectroscopy, TG-DSC, and single-crystal and powder X-ray diffraction analysis. The single-crystal X-ray diffraction data revealed that 1 and 2 are discrete structures, whereas 3 is a polymer. In 1 and 2, Ca2+ is seven-coordinate and forms a monocapped trigonal prism. In 1, the prisms are pairwise connected with the assistance of two [μ2-HTBA-O,O′]− ligands. In 3, Sr2+ is coordinated by four monodentate HTBA− via S or O donors and four waters, with the formation of a distorted square antiprism. The antiprisms are connected by μ2-O,S bridging HTBA−. Hydrogen bonding involving coordinated water and π–π interactions plays an important role in construction of the supramolecular 3-D structures in 1–3. Infrared spectroscopic data supported the structural data. The thermal stability of 1–3 decreases in the order 1 > 2 > 3. Dehydration of 1–3 was a multi-step process, followed by exothermic oxidative degradation of the 2-thiobarbiturate moiety between 290 and 800 °C.

Crystal structure of potassium 2-thiobarbiturate

The crystal and molecular structure of potassium thiobarbiturate C4H3KN2O2S (C4H4N2O2S-2-thiobarbituric acid, H2TBA) is determined. Crystallographic data for KHTBA are as follows: a = 11.2317(17) Å, b = 3.8687(6) Å, c = 14.557(2) Å, β = 97.448(4)°, V = 627.18(17) Å3, space group P2/c, Z = 4. Each potassium ion is linked with four oxygen atoms and two S atoms forming a distorted octahedron. N-H…O and C-H…S hydrogen bonds form a branched three-dimensional network. The structure is also stabilized by the π-π interaction of heterocyclic HTBA− ions.

Structures of bis(2-thiobarbiturato- O )tetraaquamagnesium and catena -[(μ 2 -2-thiobarbiturato- O,O )(2-thiobarbiturato- O ) bis(μ 2 -aqua)diaquastrontium] monohydrate

The crystal structures of bis(2-thiobarbiturato-O)tetraaquamagnesium Mg(H2O)4(HTBA-O)2I and catena-[(μ2-2-thiobarbiturato-O,O)(2-thiobarbiturato-O)bis(μ2-aqua)diaquastrontium] monohydrate catena-[Sr(μ2-H2O)2(H2O)2(μ2-HTBA-O,O)(HBTA-O)]n · nH2O (II), where H2TBA is 2-thiobarbituric acid C4H4N2O2S, have been determined. Crystal data for a=6.7598(2) Å, b = 7.6060(2) Å, c = 8.5797(2) Å, α = 79.822(2)°, β = 76.622(1)°, γ = 69.124(1)°, V = 398.82(2) Å3, space group P

Crystal structure of polymer hexaaqua-hexakis(2-thiobarbiturato)dieuropium(III)

\bar 1

Crystal structure of catena-(2-thiobarbiturato) dithallium(I)

, Z = 1; for II: a = 20.8499(4) Å, b = 19.2649(5) Å, c = 4.14007(9) Å, β = 92.023(2)°, V = 1661.91(7) Å3, space group P21/n, Z = 4. The Mg2+ ion in I is bonded to six O atoms of two HTBA− ions and four water molecules that form a nearly regular octahedron. Each Sr2+ ion in II is coordinated to three oxygen atoms of three HTBA− ions and six water molecules that form an almost ideal tricapped trigonal prism. These polyhedra share edges to form infinite chains. Intermolecular hydrogen bonds create layered structures of I and II.

Crystal structure of catena-DI(2-thiobarbiturato-O,S)aqualead(II)

Complex [Eu2(HTBA)6(H2O)6]n (I), where H2TBA is 2-thiobarbituric acid C4H4N2O2S, is synthesized. Its structure is determined by X-ray diffraction analysis (CIF file CCDC 987519). The crystals of complex I are monoclinic: a = 14.1033(4) Å, b = 10.0988(4) Å, c = 15.4061(5) Å, β = 110.003(1)°, V = 2061.9(1) Å3, space group P2/n, Z = 2. All three independent ligands HTBA− are coordinated to Eu3+ through oxygen atoms. Six HTBA− ions (two terminal and four bridging) and two water molecules are coordinated to one of the independent Eu3+ ions. The second Eu3+ ion is bound to four bridging HTBA− ions and four water molecules. The coordination polyhedra are square antiprisms. The bridging HTBA− ions join the antiprisms into layers. The structure is stabilized by numerous hydrogen bonds and the π-π interaction between HTBA−.

Crystal structures of cesium and rubidium 2-thiobarbiturates

By powder X-ray diffraction the crystal structure of catena-(2-thiobarbiturato)dithallium(I) C4H2N2O2STl2 (C4H4N2O2S is 2-thiobarbituric acid, H2TBA), Tl2TBA, is determined. Crystallographic data for Tl2TBA are as follows: a = 15.1039(3) Å, b = 12.0818(2) Å, c = 3.86455(6) Å, β = 97.203(1)°, V = 741.34(2) Å3, space group P21/n, Z = 4. There are two non-equivalent thallium atoms in the structure. The Tl1 polyhedron is a distorted trigonal prism due to the shortened Tl-S contact (3.634 Å), and the Tl2 polyhedron is a distorted square antiprism.

Crystal structure of catena-Bis(2-thiobarbiturato-O,S)diaquacadmium

The crystal structure of catena-di(μ2-2-thiobarbiturato-O,S)aqualead(II) C8H8N4O5S2Pb (C4H4N2O2S is 2-thiobarbituric acid, H2TBA) is determined. Crystallographic data for catena-[Pb(H2O)(μ2-HTBA-O,S)2] are as follows: a = 6.5972(1) Å, b = 9.8917(2) Å, c = 10.0893(2) Å, α = 106.702(1)°, β = 93.395(2)°, γ = 107.48(1)°, V = 593.82(2) Å3, space group

Synthesis and thermal transformation of a neodymium(III) complex [Nd(HTBA)2(C2H3O2)(H2O)2]·2H2O to non-centrosymmetric oxosulfate Nd2O2SO4

P\bar 1

Crystal structure of catena-(μ4-1,3-diethyl-2-thiobarbiturato-O,O’,S,S)silver(I)

, Z = 2. The Pb2+ ion is linked with six monodentate HTBA− ligands through two O atoms and four S atoms and also connected with a water molecule. Additionally, there is a shortened Pb-S contact (3.622 Å), given which the complex polyhedron represents a distorted square antiprism. Hydrogen bonds N-H…O and O-H…O form a branched three-dimensional network. The structure is also stabilized by the π-π interaction of heterocyclic HTBA− ions.