23 research outputs found
Synthesis of One- and Two-Dimensional Coordination Polymers Containing Organotin Macrocycles. Reactions of (<i>n</i>-Bu<sub>3</sub>Sn)<sub>2</sub>O with Pyridine Dicarboxylic Acids. Structure-Directing Role of the Ancillary 4,4′-Bipyridine Ligand
The reaction of (<i>n</i>-Bu<sub>3</sub>Sn)<sub>2</sub>O with pyridine-2,6-dicarboxylic acid (<b>L1H</b><sub><b>2</b></sub>) in a 1:1 ratio resulted in the formation of
a one-dimensional
(1D) coordination polymer [(<i>n</i>-Bu<sub>3</sub>Sn)<sub>2</sub>(<i>n</i>-Bu<sub>2</sub>Sn)<sub>2</sub>(μ-L1)<sub>2</sub>(μ-OH)<sub>2</sub>]<sub><i>n</i></sub> (<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>-Bu<sub>3</sub>Sn)<sub>2</sub>O with pyridine-2,5-dicarboxylic acid (<b>L2H</b><sub><b>2</b></sub>) or pyridine-3,5-dicarboxylic
acid (<b>L3H</b><sub><b>2</b></sub>), on the other hand,
results in the generation of the two-dimensional (2D) coordination
polymers [(<i>n</i>-Bu<sub>3</sub>Sn)<sub>2</sub>(μ-L2)]<sub><i>n</i></sub> (<b>2</b>) and [(<i>n</i>-Bu<sub>3</sub>Sn)<sub>4</sub>(μ-L3)<sub>2</sub>]<sub><i>n</i></sub> (<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>-Bu<sub>3</sub>Sn)<sub>2</sub>O 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>-Bu<sub>3</sub>Sn)<sub>2</sub>(μ-L1)(μ-4,4′-bipy)]<sub><i>n</i></sub> (<b>4</b>), [(<i>n</i>-Bu<sub>3</sub>Sn)<sub>2</sub>(μ-L3)(μ-4,4′-bipy)]<sub><i>n</i></sub> (<b>5</b>), and [(<i>n</i>-Bu<sub>3</sub>Sn)<sub>2</sub>(μ-L2)(μ-4,4′-bipy)]<sub><i>n</i></sub> (<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
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
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 [<sup>Benzoyl</sup>(N∧C∧N)PdBr]
(<b>16</b>) was synthesized by the oxidative addition of <sup>Benzoyl</sup>(N∧C∧N)Br to Pd(dba)<sub>2</sub> 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
[<sup>Benzoyl</sup>(N∧C∧N)PdI] (<b>17</b>) in
92% yield. Furthermore, a series of cationic palladium(II) complexes,
including [<sup>Benzoyl</sup>(N∧C∧N)Pd(MeCN)]<sup>+</sup>[BF<sub>4</sub>]<sup>−</sup> (<b>18</b>), [<sup>Benzoyl</sup>(N∧C∧N)Pd(MeCN)]<sup>+</sup>[SbF<sub>6</sub>]<sup>−</sup> (<b>19</b>), and [<sup>Benzoyl</sup>(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 AgBF<sub>4</sub>, AgSbF<sub>6</sub>, and AgOTf, respectively. Similarly, previously
synthesized <sup>Tosyl</sup>(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 AgSO<sub>3</sub>CF<sub>3</sub> and AgSbF<sub>6</sub> to afford cationic palladium(II) complexes
[<sup>Tosyl</sup>(N∧C∧N)Pd(OTf)] (<b>21</b>) and
[<sup>Tosyl</sup>(N∧C∧N)Pd(MeCN)]<sup>+</sup>[SbF<sub>6</sub>]<sup>−</sup> (<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
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, Na<sub>2</sub>[(UO<sub>2</sub>)<sub>2</sub>(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)<sub>3</sub>]·4H<sub>2</sub>O (<b>1</b>), [(UO<sub>2</sub>)<sub>4</sub>(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)<sub>5</sub>(C<sub>10</sub>H<sub>8</sub>N<sub>2</sub>)<sub>2</sub>]·C<sub>10</sub>H<sub>10</sub>N<sub>2</sub>·3H<sub>2</sub>O (<b>2</b>), [(UO<sub>2</sub>)(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)(C<sub>12</sub>H<sub>12</sub>N<sub>3</sub>)] (<b>3</b>), [(UO<sub>2</sub>)(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)(C<sub>12</sub>H<sub>12</sub>N<sub>3</sub>)]·H<sub>2</sub>O (<b>4</b>), [(UO<sub>2</sub>)<sub>2</sub>(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)<sub>3</sub>]·(C<sub>12</sub>H<sub>14</sub>N<sub>2</sub>)·5H<sub>2</sub>O (<b>5</b>), [(UO<sub>2</sub>)<sub>3</sub>(CH<sub>3</sub>CO<sub>2</sub>)(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)<sub>4</sub>](C<sub>14</sub>H<sub>17</sub>N<sub>2</sub>)<sub>3</sub>·(C<sub>14</sub>H<sub>16</sub>N<sub>2</sub>)·H<sub>2</sub>O (<b>6</b>), and [(UO<sub>2</sub>)<sub>2</sub>(C<sub>6</sub>H<sub>2</sub>O<sub>4</sub>S)<sub>3</sub>](C<sub>24</sub>H<sub>18</sub>N<sub>6</sub>) (<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 UO<sub>2</sub><sup>2+</sup> 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 UO<sub>2</sub><sup>2+</sup> 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(Br<sub>2</sub>)TeTePh to the Isolation of [{(C<sub>6</sub>H<sub>5</sub>)Te}<sub>19</sub>O<sub>24</sub>Br<sub>5</sub>]Br<sub>4</sub>
The σ-donor
ligand selone <b>L</b> (<b>L</b> =
1,3-dibutylbenzimidazolin-2-selone, C<sub>15</sub>H<sub>22</sub>N<sub>2</sub>Se) caused cleavage of the Te–Te bond of the mixed-valent
phenyltellurenyl bromide {Ph(Br<sub>2</sub>)TeTePh} in THF to produce
the selone adduct of a phenyltellurenyl cation with phenyltellurium
dibromide anion, [PhTe(L)][PhTeBr<sub>2</sub>] (<b>1</b>). The
adduct disproportionated in polar solvent (CH<sub>3</sub>CN), followed
by hydrolysis with traces of water to give the largest telluroxane
cluster, [{(C<sub>6</sub>H<sub>5</sub>)Te}<sub>19</sub>O<sub>24</sub>Br<sub>5</sub>]Br<sub>4</sub>, with a Te<sub>19</sub>O<sub>24</sub> skeleton. The bowl-shaped telluroxane cluster dimerizes in the solid state, forming the molecular
capsule {[{(C<sub>6</sub>H<sub>5</sub>)Te}<sub>19</sub>O<sub>24</sub>Br<sub>5</sub>]Br<sub>4</sub>}<sub>2</sub>. The cluster is amphipathic
and has a hydrophilic cavity consisting of tellurium, oxygen, and
bromide atoms, which contains 24H<sub>2</sub>O molecules