Synthesis of One- and Two-Dimensional Coordination Polymers Containing Organotin Macrocycles. Reactions of (<i>n</i>-Bu₃Sn)₂O with Pyridine Dicarboxylic Acids. Structure-Directing Role of the Ancillary 4,4′-Bipyridine Ligand

The reaction of (<i>n</i>-Bu₃Sn)₂O with pyridine-2,6-dicarboxylic acid (<b>L1H</b>_<b>2</b>) in a 1:1 ratio resulted in the formation of a one-dimensional (1D) coordination polymer [(<i>n</i>-Bu₃Sn)₂(<i>n</i>-Bu₂Sn)₂(μ-L1)₂(μ-OH)₂]_<i>n</i> (<b>1</b>). The formation of <b>1</b> is accompanied by a <i>Sn</i>–<i>butyl</i> bond cleavage reaction involving half of the organotin units. The formation of the 1D coordination polymer is facilitated by the multisite coordination capability of the dianionic ligand L1. The reaction of (<i>n</i>-Bu₃Sn)₂O with pyridine-2,5-dicarboxylic acid (<b>L2H</b>_<b>2</b>) or pyridine-3,5-dicarboxylic acid (<b>L3H</b>_<b>2</b>), on the other hand, results in the generation of the two-dimensional (2D) coordination polymers [(<i>n</i>-Bu₃Sn)₂(μ-L2)]_<i>n</i> (<b>2</b>) and [(<i>n</i>-Bu₃Sn)₄(μ-L3)₂]_<i>n</i> (<b>3</b>), respectively. The formation of <b>2</b> and <b>3</b> emphasizes the importance of the relative orientation of the coordinating units in the multisite coordination ligand. Compounds <b>1</b>–<b>3</b> show a rich supramolecular architecture in their solid state as a result of multiple secondary interactions. Investigation of the fate of the reactions of (<i>n</i>-Bu₃Sn)₂O with pyridine dicarboxylic acids in the presence of a bridging ligand was carried out. In all the cases when the reactions were carried out in the presence of 4,4′-bipyridine (4,4′-bipy), 1D coordination polymers [(<i>n</i>-Bu₃Sn)₂(μ-L1)­(μ-4,4′-bipy)]_<i>n</i> (<b>4</b>), [(<i>n</i>-Bu₃Sn)₂(μ-L3)­(μ-4,4′-bipy)]_<i>n</i> (<b>5</b>), and [(<i>n</i>-Bu₃Sn)₂(μ-L2)­(μ-4,4′-bipy)]_<i>n</i> (<b>6</b>) are formed. In these cases, the 4,4′-bipyridine ligand serves as one of the connectors that link the organotin units. Interestingly, in the presence of 4,4′-bipyridine, <i>Sn</i>–<i>butyl</i> bond cleavage does not take place. While the 1D coordination polymers <b>4</b> and <b>5</b> form three-dimensional supramolecular architectures in their solid state, compound <b>6</b> possesses a 2D supramolecular architecture

Synthesis, Covalency Sequence, and Crystal Features of Pentagonal Uranyl Acylpyrazolone Complexes along with DFT Calculation and Hirshfeld Analysis

Three uranyl acylpyrazolone complexes [UO2(PCBPMP)2(CH3CH2OH)] (complex I), [UO2(PCBMCPMP)2(CH3CH2OH)] (complex II), and [UO2(PCBPTMP)2(CH3CH2OH)] (complex III) were synthesized from σ-donating acypyrazolone ligands to analyze their sequence of covalent characteristics, reactivity, and redox properties (PCBPMP: p-chlorobenzoyl 1-phenyl 3-methyl 5-pyrazolone; PCBMCPMP: p-chlorobenzoyl 1-(m-chlorophenyl) 3-methyl 5-pyrazolone; PCBPTMP: p-chlorobenzoyl 1-(p-tolyl) 3-methyl 5-pyrazolone). An examination of the structure, pentagonal bipyramidal geometry, and composition of these complexes was conducted mainly through their single-crystal X-ray diffraction (XRD) data, 1H nuclear magnetic resonance (NMR) δ-values, plots of thermogravimetric-differential thermal analysis (TG-DTA), significant Fourier transform infrared (FTIR) vibrations, gravimetric estimation, and molar conductivity values. The covalency order was found to be complex II > III > I, which mainly depends on values of stretching frequencies, average bond lengths of axial uranyl bonds, values of average bond lengths on the pentagonal equatorial plane, solvent coordination on the fifth site of a pentagonal plane, and the type of aryl group on the nitrogen of the pyrazolone ring. This was confirmed by FTIR spectroscopy and single-crystal spectral characterization. To verify experimental results by comparison with theoretical results, density functional theory (DFT) calculations were carried out, which further gives evidence for the covalency order through theoretical frequencies and the gap of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies. Theoretical bond properties were also examined by the identification of global index parameters. Intermolecular noncovalent surface interactions were studied by the Hirshfeld surface analysis. The irreversible redox behavior of uranyl species was identified through electrochemical cyclic voltammetry-differential pulse voltammetry (CV-DPV) plot analysis

Synthesis, Covalency Sequence, and Crystal Features of Pentagonal Uranyl Acylpyrazolone Complexes along with DFT Calculation and Hirshfeld Analysis

Three uranyl acylpyrazolone complexes [UO2(PCBPMP)2(CH3CH2OH)] (complex I), [UO2(PCBMCPMP)2(CH3CH2OH)] (complex II), and [UO2(PCBPTMP)2(CH3CH2OH)] (complex III) were synthesized from σ-donating acypyrazolone ligands to analyze their sequence of covalent characteristics, reactivity, and redox properties (PCBPMP: p-chlorobenzoyl 1-phenyl 3-methyl 5-pyrazolone; PCBMCPMP: p-chlorobenzoyl 1-(m-chlorophenyl) 3-methyl 5-pyrazolone; PCBPTMP: p-chlorobenzoyl 1-(p-tolyl) 3-methyl 5-pyrazolone). An examination of the structure, pentagonal bipyramidal geometry, and composition of these complexes was conducted mainly through their single-crystal X-ray diffraction (XRD) data, 1H nuclear magnetic resonance (NMR) δ-values, plots of thermogravimetric-differential thermal analysis (TG-DTA), significant Fourier transform infrared (FTIR) vibrations, gravimetric estimation, and molar conductivity values. The covalency order was found to be complex II > III > I, which mainly depends on values of stretching frequencies, average bond lengths of axial uranyl bonds, values of average bond lengths on the pentagonal equatorial plane, solvent coordination on the fifth site of a pentagonal plane, and the type of aryl group on the nitrogen of the pyrazolone ring. This was confirmed by FTIR spectroscopy and single-crystal spectral characterization. To verify experimental results by comparison with theoretical results, density functional theory (DFT) calculations were carried out, which further gives evidence for the covalency order through theoretical frequencies and the gap of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies. Theoretical bond properties were also examined by the identification of global index parameters. Intermolecular noncovalent surface interactions were studied by the Hirshfeld surface analysis. The irreversible redox behavior of uranyl species was identified through electrochemical cyclic voltammetry-differential pulse voltammetry (CV-DPV) plot analysis

Synthesis, Covalency Sequence, and Crystal Features of Pentagonal Uranyl Acylpyrazolone Complexes along with DFT Calculation and Hirshfeld Analysis

Three uranyl acylpyrazolone complexes [UO2(PCBPMP)2(CH3CH2OH)] (complex I), [UO2(PCBMCPMP)2(CH3CH2OH)] (complex II), and [UO2(PCBPTMP)2(CH3CH2OH)] (complex III) were synthesized from σ-donating acypyrazolone ligands to analyze their sequence of covalent characteristics, reactivity, and redox properties (PCBPMP: p-chlorobenzoyl 1-phenyl 3-methyl 5-pyrazolone; PCBMCPMP: p-chlorobenzoyl 1-(m-chlorophenyl) 3-methyl 5-pyrazolone; PCBPTMP: p-chlorobenzoyl 1-(p-tolyl) 3-methyl 5-pyrazolone). An examination of the structure, pentagonal bipyramidal geometry, and composition of these complexes was conducted mainly through their single-crystal X-ray diffraction (XRD) data, 1H nuclear magnetic resonance (NMR) δ-values, plots of thermogravimetric-differential thermal analysis (TG-DTA), significant Fourier transform infrared (FTIR) vibrations, gravimetric estimation, and molar conductivity values. The covalency order was found to be complex II > III > I, which mainly depends on values of stretching frequencies, average bond lengths of axial uranyl bonds, values of average bond lengths on the pentagonal equatorial plane, solvent coordination on the fifth site of a pentagonal plane, and the type of aryl group on the nitrogen of the pyrazolone ring. This was confirmed by FTIR spectroscopy and single-crystal spectral characterization. To verify experimental results by comparison with theoretical results, density functional theory (DFT) calculations were carried out, which further gives evidence for the covalency order through theoretical frequencies and the gap of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies. Theoretical bond properties were also examined by the identification of global index parameters. Intermolecular noncovalent surface interactions were studied by the Hirshfeld surface analysis. The irreversible redox behavior of uranyl species was identified through electrochemical cyclic voltammetry-differential pulse voltammetry (CV-DPV) plot analysis

Synthesis, Covalency Sequence, and Crystal Features of Pentagonal Uranyl Acylpyrazolone Complexes along with DFT Calculation and Hirshfeld Analysis

Three uranyl acylpyrazolone complexes [UO2(PCBPMP)2(CH3CH2OH)] (complex I), [UO2(PCBMCPMP)2(CH3CH2OH)] (complex II), and [UO2(PCBPTMP)2(CH3CH2OH)] (complex III) were synthesized from σ-donating acypyrazolone ligands to analyze their sequence of covalent characteristics, reactivity, and redox properties (PCBPMP: p-chlorobenzoyl 1-phenyl 3-methyl 5-pyrazolone; PCBMCPMP: p-chlorobenzoyl 1-(m-chlorophenyl) 3-methyl 5-pyrazolone; PCBPTMP: p-chlorobenzoyl 1-(p-tolyl) 3-methyl 5-pyrazolone). An examination of the structure, pentagonal bipyramidal geometry, and composition of these complexes was conducted mainly through their single-crystal X-ray diffraction (XRD) data, 1H nuclear magnetic resonance (NMR) δ-values, plots of thermogravimetric-differential thermal analysis (TG-DTA), significant Fourier transform infrared (FTIR) vibrations, gravimetric estimation, and molar conductivity values. The covalency order was found to be complex II > III > I, which mainly depends on values of stretching frequencies, average bond lengths of axial uranyl bonds, values of average bond lengths on the pentagonal equatorial plane, solvent coordination on the fifth site of a pentagonal plane, and the type of aryl group on the nitrogen of the pyrazolone ring. This was confirmed by FTIR spectroscopy and single-crystal spectral characterization. To verify experimental results by comparison with theoretical results, density functional theory (DFT) calculations were carried out, which further gives evidence for the covalency order through theoretical frequencies and the gap of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies. Theoretical bond properties were also examined by the identification of global index parameters. Intermolecular noncovalent surface interactions were studied by the Hirshfeld surface analysis. The irreversible redox behavior of uranyl species was identified through electrochemical cyclic voltammetry-differential pulse voltammetry (CV-DPV) plot analysis

Cationic NCN Palladium(II) Pincer Complexes of 5-<i>tert</i>-Butyl-1,3-bis(<i>N</i>‑substituted benzimidazol-2′-yl)benzenes: Synthesis, Structure, and Pd···Pd Metallophilic Interaction

The NCN palladium­(II) pincer complex [^Benzoyl(N∧C∧N)­PdBr] (<b>16</b>) was synthesized by the oxidative addition of ^Benzoyl(N∧C∧N)Br to Pd­(dba)₂ in 85% yield [(N∧C∧N) = 5-<i>tert</i>-butyl-1,3-bis­(<i>N</i>-substituted benzimidazol-2′-yl)­phenyl)]. Then treatment of complex <b>16</b> with KI yielded the iodopalladium complex [^Benzoyl(N∧C∧N)­PdI] (<b>17</b>) in 92% yield. Furthermore, a series of cationic palladium­(II) complexes, including [^Benzoyl(N∧C∧N)­Pd­(MeCN)]⁺[BF₄]⁻ (<b>18</b>), [^Benzoyl(N∧C∧N)­Pd­(MeCN)]⁺[SbF₆]⁻ (<b>19</b>), and [^Benzoyl(N∧C∧N)­Pd­(OTf)] (<b>20</b>), were prepared in 68–79% yields by the reaction of the neutral palladium­(II) complex (<b>16</b>) with AgBF₄, AgSbF₆, and AgOTf, respectively. Similarly, previously synthesized ^Tosyl(N∧C∧N)­PdBr [5-<i>tert</i>-butyl-1,3-bis­(<i>N</i>-tosylbenzimidazol-2′-yl)­phenyl]­palladium bromide (<b>5b</b>) was treated with AgSO₃CF₃ and AgSbF₆ to afford cationic palladium­(II) complexes [^Tosyl(N∧C∧N)­Pd­(OTf)] (<b>21</b>) and [^Tosyl(N∧C∧N)­Pd­(MeCN)]⁺[SbF₆]⁻ (<b>22</b>) in 41 and 61% yields, respectively. 5-<i>tert</i>-Butyl-1,3-bis­[{(<i>N</i>-tosylbenzimidazol-2′-yl)­phenyl}­palladium­(II)] triflate (<b>21</b>) exhibited an unsupported metallophillic Pd···Pd interaction [3.166(8) Å] that is corroborated by X-ray crystallographic studies. Compared to other cationic palladium complexes, complex <b>21</b> was found to be less stable. In Atoms in Molecule (AIM) analysis, the bond critical point (ρ) between Pd and Pd atoms is 0.000865 au, supporting the presence of metallophillic interaction in complex <b>21</b>. The bond strength of the Pd···Pd bond was also measured by density functional theory calculations that indicated that the calculated bond order was approximately one-fourth of the normal covalent Pd–Pd bond (natural atomic orbital bond order method). All eight complexes, two neutral and six cationic, were characterized by common spectroscopic techniques, and six complexes were corroborated by X-ray diffraction studies

Synthesis of Selenenium Ions: Isolation of Highly Conjugated, pH-Sensitive 4,4′-Bis(methylimino)-1,1′-binaphthylene-5-diselenenium(II) Triflate

The isolation of novel selenenium cations, stabilized by only one intramolecularly coordinating group (Se···N), is described. The electronic nature of the cations has been probed by calculating natural bonding orbital charges and Wiberg bond indices. [8-(Dimethylamino)-1-naphthyl]­selenenyl­(II) triflate oxidizes in methanol via C–C coupling to give a novel blue-colored 4,4′-bis­(methylimino)-1,1′-binaphthylene-5-diselenenium­(II) triflate. The pH dependence of the color has been investigated

Role of N‑Donor Sterics on the Coordination Environment and Dimensionality of Uranyl Thiophenedicarboxylate Coordination Polymers

Thiophene 2,5-dicarboxylic acid (TDC) was reacted with uranyl acetate dihydrate and one (or none) of six N-donor chelating ligands (2,2′-bipyridine (BPY), 4,4′-dimethyl-2,2′-bipyridine (4-MeBPY), 5,5′-dimethyl-2,2′-bipyridine (5-MeBPY), 6,6′-dimethyl-2,2′-bipyridine (6-MeBPY), 4,4′,6,6′-tetramethyl-2,2′-bipyridine (4,6-MeBPY), and tetrakis­(2-pyridyl)­pyrazine (TPPZ) to result in the crystallization of seven uranyl coordination polymers, which were characterized by their crystal structures and luminescence properties. The seven coordination polymers, Na₂[(UO₂)₂­(C₆H₂O₄S)₃]·4H₂O (<b>1</b>), [(UO₂)₄­(C₆H₂O₄S)₅­(C₁₀H₈N₂)₂]·C₁₀H₁₀N₂·3H₂O (<b>2</b>), [(UO₂)­(C₆H₂O₄S)­(C₁₂H₁₂N₃)] (<b>3</b>), [(UO₂)­(C₆H₂O₄S)­(C₁₂H₁₂N₃)]·H₂O (<b>4</b>), [(UO₂)₂­(C₆H₂O₄S)₃]·(C₁₂H₁₄N₂)·5H₂O (<b>5</b>), [(UO₂)₃­(CH₃CO₂)­(C₆H₂O₄S)₄]­(C₁₄H₁₇N₂)₃·(C₁₄H₁₆N₂)·H₂O (<b>6</b>), and [(UO₂)₂­(C₆H₂O₄S)₃]­(C₂₄H₁₈N₆) (<b>7</b>), consist of either uranyl hexagonal bipyramidal or pentagonal bipyramidal coordination geometries. In all structures, structural variations in the local and global structures of <b>1</b>–<b>7</b> are influenced by the positions (or number) of methyl groups or pyridyl rings on the N-donor species, thus resulting in a wide diversity of structures ranging from single chains, double chains, or 2-D sheets. Direct coordination of N-donor ligands to uranyl centers is observed in the chain structures of <b>2</b>–<b>4</b> using BPY, 4-MeBPY, and 5-MeBPY, whereas the N-donor species participate as guests (as either neutral or charge balancing species) in the chain and sheet structures of <b>5</b>–<b>7</b> using 6-MeBPY, 4,6-MeBPY, and TPPZ, respectively. Compound <b>1</b> is the only structure that does not contain any N-donor ligands and thus crystallizes as a 2-D interpenetrating sheet. The luminescent properties of <b>1</b>–<b>7</b> are influenced by the direct coordination or noncoordination of N-donor species to uranyl centers. Compounds <b>2</b>–<b>4</b> exhibit typical UO₂²⁺ emission upon direct coordination of N-donors, but its absence is observed in <b>1</b>, <b>5</b>, <b>6</b>, and <b>7</b>, when N-donor species participate as guest molecules. These results suggest that direct coordination of N-donor ligands participate as chromophores, thus resulting in possible UO₂²⁺ sensitization. The lack of emission in <b>1</b>, <b>5</b>, <b>6</b>, and <b>7</b> may be explained by the extended conjugation of the TDC ligands within their structures

Theoretical investigation on molecular structure of a new mononuclear copper(II) thiocyanato complex with tridentate Schiff base ligand

<p>An asymmetrical Schiff base ligand, 4-bromo-2-(2-pyridylmethyliminomethyl)phenol (HL), and its copper(II) complex, [Cu(L)SCN] (<b>1</b>), have been synthesized. Complex <b>1</b> is experimentally characterized by elemental analysis, FT-IR and UV–vis spectroscopic techniques, and cyclic voltammetry. The structure of the complex has been established by single-crystal X-ray diffraction studies, which reveal a square planar geometry of the central copper(II) ion in <b>1</b>. The neighboring molecules of the complex connect each other by π–π stacking interactions with centroid-to-centroid ring distance 3.653 Å. The ligand can display two possible tautomeric forms; therefore, <b>1</b> can have an alternate molecular structure. DFT calculations have been employed to investigate the structure and relative stabilities of the suggested tautomeric forms of the ligand and its corresponding copper(II) complex.</p

From Mixed-Valent Phenyltellurenyl Bromide Ph(Br₂)TeTePh to the Isolation of [{(C₆H₅)Te}₁₉O₂₄Br₅]Br₄

The σ-donor ligand selone <b>L</b> (<b>L</b> = 1,3-dibutylbenzimidazolin-2-selone, C₁₅H₂₂N₂Se) caused cleavage of the Te–Te bond of the mixed-valent phenyltellurenyl bromide {Ph­(Br₂)­TeTePh} in THF to produce the selone adduct of a phenyltellurenyl cation with phenyltellurium dibromide anion, [PhTe­(L)]­[PhTeBr₂] (<b>1</b>). The adduct disproportionated in polar solvent (CH₃CN), followed by hydrolysis with traces of water to give the largest telluroxane cluster, [{(C₆H₅)­Te}₁₉O₂₄Br₅]­Br₄, with a Te₁₉O₂₄ skeleton. The bowl-shaped telluroxane cluster dimerizes in the solid state, forming the molecular capsule {[{(C₆H₅)­Te}₁₉O₂₄Br₅]­Br₄}₂. The cluster is amphipathic and has a hydrophilic cavity consisting of tellurium, oxygen, and bromide atoms, which contains 24H₂O molecules