Crystal structure of bis(tetramethylthiourea-κS)bis(thiocyanato-κN)cobalt(II)

In the course of systematic investigations on the synthesis of Co(NCS)2 coordination compounds with different thiourea ligands, the title compound, [Co(NCS)2(C5H12N2S)2], was obtained. In this compound the CoII cations are coordinated by two crystallographically independent N-bonded thiocyanate anions and two tetramethylthiourea ligands into discrete complexes that are located in general positions and show a strongly distorted tetrahedral geometry. Intermolecular C—H...S hydrogen bonds of different strength can be observed between the discrete complexes, which are connected by pairs of hydrogen bonds into zigzag-like chains that elongate in the b-axis direction. These chains are additionally linked by strong C—H...S hydrogen bonds along the a-axis direction, resulting in the formation of layers that are parallel to the ab plane. There is also one weak intramolecular C—H...S hydrogen bond between two neighbouring thiourea ligands within the complexes. Comparison of the experimental PXRD pattern with that calculated from the single-crystal data prove that a pure phase has been obtained. Thermoanalytical investigations reveal that this compound melts at 364 K and decomposes upon further heating.

Structural diversity in Cd(NCS)2-3-cyanopyridine coordination compounds: synthesis, crystal structures and thermal properties

Five new compounds with the compositions [Cd(NCS)2(3-cyanopyridine)2]n · 3-cyanopyridine (1), [Cd(NCS)2(3-cyanopyridine)2]n · 1/3 3-cyanopyridine (2), [Cd(NCS)2(3-cyanopyridine)2]n (3), {[Cd(NCS)2]2(3-cyanopyridine)3}n (4), and {[Cd(NCS)2]3(3-cyanopyridine)4}n (5) have been obtained by the reaction of Cd(NCS)2 with 3-cyanopyridine in different solvents. While large amounts of compounds 1–4 could be prepared as powders, only a few single crystals of 5 were accidently obtained. Thermoanalytical investigations have shown that 4 could also be obtained by annealing of 1 or 2 and that under slightly different conditions 5 could be obtained as part of a mixture with 4. The crystal structures of all compounds can be divided in two sets of compounds. Compounds 1, 2 and 3 consist of chains in which the Cd cations show three different coordination environments and in which the coligands are only terminally bonded. In the structures of 4 and 5 similar chains are observed, which are connected into layers via some of the 3-cyanopyridine coligands.

Crystal Structure and Characterization of Two Layered Copper(II) Coordination Polymers with Anions of 3-Phosphonopropionic Acid and (RS)-2-Phosphonobutyric Acid

Blue single crystals of Cu[μ3-O3P(CH2)2COOH].2H2O (1) and Cu[(RS)-μ3-O3PCH(C2H5)COOH].3H2O (2) have been prepared in aqueous Cu2+-solutions (pH = 2.5–3.5) containing 3-phosphonopropionic acid (1) and (RS)-2-phosphonobutyric acid (2), respectively. 1: Space group Pbca (no. 61) with a = 812.5(2), b = 919.00(9), c = 2102.3(2) pm. Cu2+ is five-fold coordinated by three oxygen atomsstemming from [O3P(CH2)2COOH]2– anions and two water molecules. The Cu-O bond lengths range from194.0(3) to 231.8(4) pm. The connection between the [O3P(CH2)2COOH]2– anions and the Cu2+ cations yields apolymeric structure with layers parallel to (001). The layers are linked by hydrogen bonds. 2: Space group Pbca(no. 61) with a = 1007.17(14), b = 961.2(3), c = 2180.9(4) pm. The copper cations are surrounded by five oxygen atoms in a square pyramidal fashion with Cu-O bonds between 193.6(4) and 236.9(4) pm. The coordination between [O3PCH(C2H5)COOH]2- and Cu2+ results in infinite puckered layers parallel to (001). The layers are not connected by any hydrogen bonds. Each layer contains both R and S isomers of the [O3PCH(C2H5)COOH]2-dianion. Water molecules not bound to Cu2+ are intercalated between the layers.UV/Vis spectra suggest three d-d transition bands at 743, 892, 1016 nm for 1 and four bands at 741, 838, 957and 1151 nm for 2, respectively. Magnetic measurements suggest a weak antiferromagnetic coupling betweenCu2+ due to a super-superexchange interaction. Thermoanalytical investigations in air show that the compounds are stable up to 95 °C (1) and 65 °C (2), respectively.

A Novel One-Dimensional Copper Mellitate Complex Featured by {Cu(H2O)2(urea)[C6(COO)4(COOH)2]}n 2n- Polyanions

Blue monoclinic single crystals of the novel one-dimensional [H3N-(CH2)6-NH3][Cu(H2O)2(urea)(μ2-C6(COO)4 (COOH)2)]H2O coordination polymer have beenprepared in aqueous solution at room temperature in the presence of 1,6-diaminohexane andurea. Space group P21/n (no. 14) with a = 958.48(9), b = 1465.74(11), c = 1821.14(12) pm, beta= 97.655(8)°. The Cu2+ cation is coordinated in a square pyramidal manner by two oxygen atoms stemming from the dihydrogen mellitate tetraanion, one oxygen atom from the ureamolecule, and two water molecules. The Cu−O distances are between 193.3(2) and 229.4(2)pm. The connection between Cu2+ and [C6(COO)4(COOH)2]4 yields infinite chain-likepolyanions parallel to [ 01] with a composition of{Cu(H2O)2(urea)[C6(COO)4(COOH)2]}n2n-. The dihydrogen mellitate tetraanion adopts a μ2coordination mode. The [(H3N-(CH2)6-NH3)]2+ cations are accommodated between the chainsas counter cations. The hexane-1,6-diammonium cations adopt a partial synclinal conformation. The chains are connected by strong and weak hydrogen bonds. Magneticmeasurements reveal a paramagnetic Curie-Weiss behaviour and a magnetic moment of 1.93μB per Cu2+. Thermoanalytical investigations in air show that the complex is stable up to 135°C. Following decomposition processes yielding CuO.

Synthesis, Crystal Structure and Hydrogen Bonding of μ- Hydroxo-μ-peroxo-bis[bis(ethylenediamine)cobalt(III)] squarate

Black-brown needle-shaped single crystals of [Co2(en)4(O2)(OH)][C4O4]1.5 4H2O(en = ethylenediamine) have been prepared in aqueous solution at room temperature. Spacegroup P-1 (no.2) with a = 800.20(8), b = 1225.48(7), c = 1403.84(9) pm, = 100.282(5), =94.515(7), = 95.596(6)°. The Co3+ cations [Co(1), Co(2)] are coordinated in an octahedralmanner by four nitrogen atoms stemming from the ethylenediamine molecules and twooxygen atoms each from a hydroxo group and a peroxo group, respectively. Both Co3+coordination polyhedra are connected by a common corner and by the peroxo group leadingto the binuclear [(en)2Co(O2)(OH)Co(en)2]3+ cation. The squarate dianions, not bonded toCo3+, and the [(en)2Co(O2)(OH)Co(en)2]3+ cations are linked by hydrogen bonds forming athree-dimensional supramolecular network containing water molecules. Magneticmeasurements reveal a diamagnetic behaviour indicating a low-spin electron configuration ofCo3+. The UV-Vis spectra shows two LMCT bands ( *(O22 ) d *(Co3+)) at 274 and 368nm and the d-d transition (1A1g 1T1g) at 542 nm. Thermoanalytical investigations in airshow that the compound is stable up to 120 °C. Subsequent decomposition processes to cobaltoxide are finished at 460 °C.

Synthesis, Crystal Structure and Characterization of Two Novel One- and Two-Dimensionally Polymeric Copper(II) Phosphonoacetates

Blue single crystals of Cu[μ2-OOC(CH2)PO3H].2H2O (1) and Cu1.5[μ3-OOC(CH2)PO3].5H2O (2) havebeen prepared in aqueous solution. 1: Space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2)pm, beta = 122.45(1)°. Cu is coordinated by three oxygen atoms stemming from the hydrogenphosphonoacetatedianion and three water molecules to form a distorted octahedron. The Cu-O bonds range from 190.4(3) to278.5(3) pm. The connection between the Cu2+ cations and the hydrogenphosphonoacetate dianions leads to atwo-dimensional structure with layers parallel to ( 01). The layers are linked by hydrogen bonds. 2: Space group(no. 2) with a = 608.2(1), b = 800.1(1), c = 1083.6(1) pm, alpha = 94.98(1)°, beta = 105.71(1)°, gamma = 109.84(1)°.There are two crystallographically independent Cu2+ cations coordinated in a square pyramidal and an octahedralfashion, respectively. The Cu-O bonds range from 192.9(2) to 237.2(2) pm. The coordination of thephosphonoacetate trianion to Cu(1) results in infinite polyanionic chains parallel to [100] with a composition of{Cu(H2O)[OOC(CH2)PO3]}nn-. Hydrated Cu(2) cations are accommodated between the chains as counter ions. 1and 2 show structural features of cation exchangers. Magnetic measurements reveal a paramagnetic Curie-Weiss behaviour. Compound 2 shows antiferromagnetic coupling between Cu2+ ions due to a super-superexchangecoupling. The UV/Vis spectra of 1 suggests three d-d transition bands at 763 nm (2B1 - 2E), 878 nm (2B1 -2B2), and 1061 nm (2B1 - 2A1). Thermoanalytical investigations in air show that compound 1 is stable up to 165°C, whereas the decomposition of 2 begins at 63 °C.

Conformational trimorphism of bis(2,6-dimesitylphenyl)ditelluride

Besides the previously known α-form (monoclinic, P21/c, Z=4) of bis(2,6-dimesitylphenyl)ditelluride, two new polymorphic modifications, namely the β-form (monoclinic, P21/c, Z=8) and the γ-form (triclinic, P1̅, Z=2), were obtained serendipitously during chemical reactions. In all three modifications, the individual molecules possess significantly different conformations and bond parameters, such as Te–Te bond lengths, C–Te–Te bond angles, C–Te–Te–C torsion angles and intramolecular Menshutkin interactions, which is also reflected in their non-covalent interactions with adjacent molecules in the crystal lattice via London dispersion and electrostatic forces. The interplay between intermolecular and intramolecular forces in these conformational polymorphs was investigated using quantum chemical calculations, which reveal that the β-form should be thermodynamically stable at absolute zero. In contrast, crystallization experiments and thermoanalytical investigations indicate that the α-form is stable at high temperatures and therefore, both forms might be related by enantiotropism.