Hui‐Ting Wang

A Switchable Molecular Dielectric with Two Sequential Reversible Phase Transitions: [(CH3)4P]4[Mn(SCN)6]

A new organic-inorganic hybrid switchable and tunable dielectric compound, [(CH3)4P]4[Mn(SCN)6] (1), exhibits three distinct dielectric states above room temperature and undergoes two reversible solid-state phase transitions, including a structural phase transition at 330 K and a ferroelastic phase transition with the Aizu notation of mmmF2/m at 352 K. The variable-temperature structural analyses disclose that the origin of the phase transitions and dielectric anomalies can be ascribed to the reorientation or motion of both the [(CH3)4P](+) cations and [Mn(SCN)6](4-) anions in solid-state crystals.

A new three-dimensional anionic cadmium(II) dicyanamide network

A new cadmium dicyanamide complex, poly[tetramethylphosphonium [μ-chlorido-di-μ-dicyanamido-κ(4)N(1):N(5)-cadmium(II)]], [(CH3)4P][Cd(NCNCN)2Cl], was synthesized by the reaction of tetramethylphosphonium chloride, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution. In the crystal structure, each Cd(II) atom is octahedrally coordinated by four terminal N atoms from four anionic dicyanamide (dca) ligands and by two chloride ligands. The dicyanamide ligands play two different roles in the building up of the structure; one role results in the formation of [Cd(dca)Cl]2 building blocks, while the other links the building blocks into a three-dimensional structure. The anionic framework exhibits a solvent-accessible void of 673.8 Å(3), amounting to 47.44% of the total unit-cell volume. The cavities in the network are occupied by pairs of tetramethylphosphonium cations.

Two different anionic manganese(II) coordination polymers constructed through dicyanamide coordination bridges.

In order to explore new metal coordination polymers and to search for new types of ferroelectrics among hybrid coordination polymers, two manganese dicyanamide complexes, poly[tetramethylammonium [di-μ3-dicyanamido-κ(6)N(1):N(3):N(5)-tri-μ2-dicyanamido-κ(6)N(1):N(5)-dimanganese(II)]], {[(CH3)4N][Mn2(NCNCN)5]}n, (I), and catena-poly[bis(butyltriphenylphosphonium) [[(dicyanamido-κN(1))manganese(II)]-di-μ2-dicyanamido-κ(4)N(1):N(5)]], {[(C4H9)(C6H5)3P]2[Mn(NCNCN)4]}n, (II), were synthesized in aqueous solution. In (I), one Mn(II) cation is octahedrally coordinated by six nitrile N atoms from six anionic dicyanamide (dca) ligands, while the second Mn(II) cation is coordinated by four nitrile N atoms and two amide N atoms from six anionic dca ligands. Neighbouring Mn(II) cations are linked together by μ-1,5- and μ-1,3,5-bridging dca anions to form a three-dimensional polymeric structure. The anionic framework exhibits a solvent-accessible void of 289.8 Å(3), amounting to 28.0% of the total unit-cell volume. Each of the cavities in the network is occupied by only one tetramethylammonium cation. In (II), each Mn(II) cation is octahedrally coordinated by six nitrile N atoms from six dca ligands. Neighbouring Mn(II) cations are linked together by double dca bridges to form a one-dimensional polymeric chain, and C-H...N hydrogen-bonding interactions are involved in the formation of the one-dimensional layer structure.

A new three-dimensional CdII supramolecular framework constructed from the 1-[(1H-tetrazol-5-yl)methyl]-1,4-diazoniabicyclo[2.2.2]octane ligand.

A new tetrazole-metal supramolecular compound, di-μ-chlorido-bis(trichlorido{1-[(1H-tetrazol-5-yl-κN(2))methyl]-1,4-diazoniabicyclo[2.2.2]octane}cadmium(II)), [Cd2(C8H16N6)2Cl8], has been synthesized and structurally characterized by single-crystal X-ray diffraction. In the structure, each Cd(II) cation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from the 1-[(1H-tetrazol-5-yl)methyl]-1,4-diazoniabicyclo[2.2.2]octane ligand, adopting a slightly distorted octahedral coordination geometry. The bridging bicyclo[2.2.2]octane and chloride ligands link the Cd(II) cations into one-dimensional ribbon-like N-H...Cl hydrogen-bonded chains along the b axis. An extensive hydrogen-bonding network formed by N-H...Cl and C-H...Cl hydrogen bonds, and interchain π-π stacking interactions between adjacent tetrazole rings, consolidate the crystal packing, linking the poymeric chains into a three-dimensional supramolecular network.

A new two-dimensional anionic cadmium(II) polymer constructed through thiocyanate coordination bridges.

A new cadmium-thiocyanate complex, poly[4-(dimethylamino)pyridin-1-ium [di-μ-thiocyanato-κ(2)N:S;κ(2)S:N-thiocyanato-κN-cadmium(II)]], {(C7H11N2)[Cd(NCS)3]}n, was synthesized by the reaction of cadmium thiocyanate and 4-(dimethylamino)pyridine hydrochloride in aqueous solution. In the crystal structure, each Cd(II) ion is square-pyramidally coordinated by three N and two S atoms from five different thiocyanate ligands, four of which are bridging. The thiocyanate ligands play different roles in the build up of the structure; one role results in the formation of [Cd2(NCS)2] building blocks, while the other links the building blocks and cations via N-H···S hydrogen bonds. The N-H···S hydrogen bonds and weak π-π stacking interactions are involved in the formation of both a two-dimensional network structure and the supramolecular network.

A two-dimensional anionic CdII polymer constructed through dicyanamide coordination bridges.

In the search for potential ferroelectric materials, molecular-based one-, two- and three-dimensional cadmium(II) organic-inorganic compounds have been of interest as they often display solid-solid phase transitions induced by a variation in temperature. A new cadmium dicyanamide complex, poly[4-dimethylamino-1-ethylpyridin-1-ium [tri-μ-dicyanamido-κ(6)N(1):N(5)-cadmium(II)]], {(C9H15N2)[Cd(C2N3)3]}n, was synthesized by the reaction of 4-dimethylamino-1-ethylpyridin-1-ium bromide, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution. In the crystal structure, each Cd(II) cation is octahedrally coordinated by six terminal N atoms from six anionic dicyanamide (dca) ligands. Neighbouring Cd(II) cations are linked together by dicyanamide bridges to form a two-dimensional coordination polymer. The organic cations are not involved in the formation of the supramolecular network.

A two-dimensional cadmium(II) polymer based on nicotinic acid and thiocyanate ligands.

A cadmium-thiocyanate complex, poly[[bis(nicotinic acid-κN)di-μ-thiocyanato-κ(2)N:S;κ(2)S:N-cadmium(II)] monohydrate], {[Cd(NCS)2(C6H5NO2)2]·H2O}n, was synthesized by the reaction of nicotinic acid, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, each Cd(II) cation is in a distorted octahedral coordination environment, coordinated by the N and S atoms of nicotinic acid and thiocyanate ligands. Neighbouring Cd(II) cations are linked together by thiocyanate bridges to form a two-dimensional network. Hydrogen-bond interactions between the uncoordinated solvent water molecules and the organic ligands result in the formation of the three-dimensional supramolecular network.

A two-dimensional cadmium(II) coordination polymer based on 1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane and thiocyanate ligands.

A cadmium-thiocyanate complex, poly[(1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane-κ(4)N)octakis-μ2-thiocyanato-κ(8)N:S;κ(8)S:N-tricadmium(II)], [Cd3(C8H14N3)2(NCS)8]n, was synthesized by the reaction of 1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, there are two independent types of Cd(II) cation (one on a centre of inversion and one in a general position) and both are in distorted octahedral coordination environments, coordinated by N and S atoms from different ligands. Neighbouring Cd(II) cations are linked together by thiocyanate bridges to form a two-dimensional network. Hydrogen-bonding interactions are involved in the formation of a three-dimensional supramolecular network.