Stabilization of Super Electrophilic Pd+2 Cations in Small-Pore SSZ-13 Zeolite

We provide the first observation and characterization of super-electrophilic metal cations on a solid support. For Pd/SSZ-13 the results of our combined experimental (FTIR, XPS, HAADF-STEM) and density functional theory study reveal that Pd ions in zeolites, previously identified as Pd+3 and Pd+4, are in fact present as super electrophilic Pd+2 species (charge-transfer complex/ion pair with the negatively charged framework oxygens). In this contribution we re-assign the spectroscopic signatures of these species, discuss the unusual coordination environment of “naked” (ligand-free) super-electrophilic Pd+2 in SSZ-13, and their complexes with CO and NO. With CO, non-classical, highly positive [Pd(CO)2]2+ ions are formed with the zeolite framework acting as a weakly coordinating anion (ion pairs). Non-classical carbonyl complexes also form with Pt+2 and Ag+ in SSZ-13. The Pd+2(CO)2 complex is remarkably stable in zeolite cages even in the presence of water. Dicarbonyl and nitrosyl Pd+2 complexes, in turn, serve as precursors to the synthesis of previously inaccessible Pd+2-carbonyl-olefin [Pd(CO)(C2H4)] and -nitrosyl-olefin [Pd(NO)(C2H4)] complexes. Overall, we show that zeolite framework can stabilize super electrophilic metal (Pd) cations, and show the new chemistry of Pd/SSZ-13 system with implications for adsorption and catalysis.

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Stabilization of Super Electrophilic Pd+2 Cations in Small-Pore SSZ-13 Zeolite

10.26434/chemrxiv.7789454.v1 ◽

2019 ◽

Author(s):

Konstantin Khivantsev ◽

Nicholas R. Jaegers ◽

Iskra Z. Koleva ◽

Hristiyan A. Aleksandrov ◽

Libor Kovarik ◽

...

Keyword(s):

Density Functional ◽

Ion Pairs ◽

Carbonyl Complexes ◽

Zeolite Framework ◽

Functional Theory ◽

Coordination Environment ◽

Small Pore ◽

Ligand Free ◽

Spectroscopic Signatures ◽

Insight Into

<div> The results of our combined experimental (FTIR, XPS, HAADF-STEM, EXAFS) and density functional theory study reveal that Pd ions in zeolites, previously identified as Pd+3 and Pd+4, are in fact present as super electrophilic Pd+2 species (ion pairs with the negatively charged framework oxygens). In this contribution we re-assign the spectroscopic signatures of these species, discuss the unusual coordination environment of “naked” (ligand-free) Pd+2 in SSZ-13, and their complexes with CO and NO. With CO, non-classical, highly positive [Pd(CO)2]2+ ions are formed with the zeolite framework acting as a weakly coordinating anion (ion pairs). Non-classical carbonyl complexes also form with Pt+2 and Ag+ in SSZ-13. The Pd+2(CO)2 complex is remarkably stable in zeolite cages even in the presence of water. Dicarbonyl and nitrosyl Pd+2 complexes, in turn, serve as precursors to the synthesis of previously inaccessible Pd+2-carbonyl-olefin [Pd(CO)(C2H4)] and -nitrosyl-olefin [Pd(NO)(C2H4)] complexes. Overall, we provide novel insight into the interactions of divalent metals with the zeolite framework, and show the new chemistry of Pd/SSZ-13 system with implications for adsorption and catalysis. </div>

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Density functional theory (DFT) calculations on the structures and stabilities of [CnO2n+1]2– and [CnO2n+1]X2 polycarbonates containing chainlike (CO2)n units (n = 2–6; X = H or Li)

Canadian Journal of Chemistry ◽

10.1139/v11-039 ◽

2011 ◽

Vol 89 (6) ◽

pp. 671-687 ◽

Cited By ~ 6

Author(s):

Pablo J. Bruna ◽

Friedrich Grein ◽

Jack Passmore

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Ion Pairs ◽

Dicarboxylic Acids ◽

Polarizable Continuum Model ◽

Weakly Bound ◽

Functional Theory ◽

The Density Functional Theory ◽

Weakly Bound Complexes

The structures and stabilities of chainlike (CO2)n (n = 2–6) polycarbonates, where adjacent C atoms are linked by C–O–C bonds, were investigated at the density functional theory (DFT) level (B3PW91/6–311G(2d,p)), including dicarboxylic dianions, [CnO2n+1]2–, and the corresponding acids, [CnO2n+1]H2, and Li salts, [CnO2n+1]Li2. At equilibrium, the most stable systems have Cs, C2, or C2v symmetries. In the gas phase, these dianions are generally metastable with respect to spontaneous ejection of one electron, yet in the presence of counterions they become stabilized, for example, as [CnO2n+1]2–(Li+)2 ion pairs. [CnO2n+1]2– linkages are also stabilized as dicarboxylic acids, [CnO2n+1]H2; we find the latter to have equilibrium conformations of higher symmetry than previously reported in the literature. To the best of our knowledge, none of the [CnO2n+1]X2 (X = Li or H) compounds with n ≥ 2 have been reported in the experimental literature (albeit, the alkyl esters C2O5R2 and C3O7R2 are commercially available). All CO bonds in C2O5X2 to C6O13X2 have single- to double-bond character (≈140–118 pm), indicating that the [CnO2n+1] moieties are held together by strong chemical forces (in contrast to the weakly bound complexes (CO2)n and (CO2)n–, n > 1). Vibrational frequencies were calculated to ensure all conformations were true minima. The IR and Raman intensities show that the high intensity C=O stretching modes (1750 ± 100 cm–1) will help in the spectral characterization of these compounds. Solvation calculations using the polarizable continuum model (PCM) find that C2O52– can be formed via CO32– + CO2 as well as CO3–[Formula: see text], each reaction having ΔG298 < 0 in practically all solvents. This result confirms the experimentally observed large solubility of CO2(g) in molten carbonates, CO3M2 (M = Li, Na, or K). In contrast, starting with n = 2, the reactions [CnO2n+1]2– + CO2 do not proceed spontaneously in any solvent (ΔG298 > 0).

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Computational Characterization of Bidentate P-Donor Ligands: Direct Comparison to Tolman’s Electronic Parameters

Molecules ◽

10.3390/molecules23123176 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3176 ◽

Cited By ~ 4

Author(s):

Tímea Kégl ◽

Noémi Pálinkás ◽

László Kollár ◽

Tamás Kégl

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Metal Carbonyl ◽

Donor Ligands ◽

Carbonyl Complexes ◽

Electronic Effects ◽

Functional Theory ◽

Metal Carbonyl Complexes ◽

Electronic Parameters

The applicability of two types of transition-metal carbonyl complexes as appropriate candidates for computationally derived Tolman’s ligand electronic parameters were examined with density functional theory (DFT) calculations employing the B97D3 functional. Both Pd(0)L2(CO) and HRh(I)L2(CO) complexes correlated well with the experimental Tolman Electronic Parameter scale. For direct comparison of the electronic effects of diphosphines with those of monophosphines, the palladium-containing system is recommended. The t r a n s influence of various phosphines did not show a major difference, but the decrease of the H-Rh-P angle from linear can cause a significant change.

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Synthesis and Characterization of Ion Pairs between Alkaline Metal Ions and Anionic Anti-Aromatic and Aromatic Hydrocarbons with π-Conjugated Central Seven- and Eight-Membered Rings

Molecules ◽

10.3390/molecules25204742 ◽

2020 ◽

Vol 25 (20) ◽

pp. 4742

Author(s):

Jan Bloch ◽

Stefan Kradolfer ◽

Thomas L. Gianetti ◽

Detlev Ostendorf ◽

Subal Dey ◽

...

Keyword(s):

Metal Ions ◽

Density Functional ◽

Ion Pairs ◽

Alkaline Metal ◽

Functional Theory ◽

Full Characterization ◽

Aromatic Character ◽

Counter Cation ◽

Solvent Molecules

The synthesis, isolation and full characterization of ion pairs between alkaline metal ions (Li+, Na+, K+) and mono-anions and dianions obtained from 5H-dibenzo[a,d]cycloheptenyl (C15H11 = trop) is reported. According to Nuclear Magnetic Resonance (NMR) spectroscopy, single crystal X-ray analysis and Density Functional Theory (DFT) calculations, the trop‒ and trop2−• anions show anti-aromatic properties which are dependent on the counter cation M+ and solvent molecules serving as co-ligands. For comparison, the disodium and dipotassium salt of the dianion of dibenzo[a,e]cyclooctatetraene (C16H12 = dbcot) were prepared, which show classical aromatic character. A d8-Rh(I) complex of trop− was prepared and the structure shows a distortion of the C15H11 ligand into a conjugated 10π -benzo pentadienide unit—to which the Rh(I) center is coordinated—and an aromatic 6π electron benzo group which is non-coordinated. Electron transfer reactions between neutral and anionic trop and dbcot species show that the anti-aromatic compounds obtained from trop are significantly stronger reductants.

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Structural and computational investigation of an imine-based propeller-shaped macrocyclic cage

SN Applied Sciences ◽

10.1007/s42452-021-04255-7 ◽

2021 ◽

Vol 3 (2) ◽

Author(s):

Sriram Srinivasa Raghvan ◽

Suresh Madhu ◽

Velmurugan Devadasan ◽

Gunasekaran Krishnasamy

Keyword(s):

Band Gap ◽

Density Functional ◽

Strain Tensor ◽

Strong Interactions ◽

Soft Condensed Matter ◽

Functional Theory ◽

Self Assembling ◽

Phenyl Rings ◽

Crystal Volume

AbstractIn this study, we present the synthesis, spectroscopic and structural characterization of self-assembling gem-dimethyl imine based molecular cage (IMC). Self-assembling macrocycles and cages have well-defined cavities and have extensive functionalities ranging from energy storage, liquid crystals, and catalysts to water splitting photo absorber. IMC has large voids i.e., 25% of the total crystal volume thus could accommodate wide substrates. The synthesized imine-based molecular cages are stabilized by coaxial π bonded networks and long-range periodic van der Waal and non-bonded contacts as observed from the crystal structure. IMC also has typical properties of soft condensed matter materials, hence theoretical prediction of stress and strain tensor along with thermophysical properties were computed on crystal system and were found to be stable. Molecular dynamics revealed IMC is stabilized by, strong interactions between the interstitial phenyl rings. Density functional theory (DFT) based physicochemical properties were evaluated and has band gap of around 2.38ev (520 nm) similar to various photocatalytic band gap materials.

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A Hybrid Cylindrical Model for Characterization of MCM-41 by Density Functional Theory.

ChemInform ◽

10.1002/chin.200444002 ◽

2004 ◽

Vol 35 (44) ◽

Author(s):

Bei Liu ◽

Wenchuan Wang ◽

Xianren Zhang

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Functional Theory ◽

Cylindrical Model ◽

Mcm 41

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Metal-Rich Metallaboranes: Synthesis, Structures and Bonding of Bi- and Trimetallic Open-Faced Cobaltaboranes

Inorganics ◽

10.3390/inorganics9040028 ◽

2021 ◽

Vol 9 (4) ◽

pp. 28

Author(s):

Kriti Pathak ◽

Chandan Nandi ◽

Jean-François Halet ◽

Sundargopal Ghosh

Keyword(s):

Electronic Structures ◽

Density Functional ◽

Room Temperature ◽

Electron Pair ◽

X Ray Diffraction ◽

Functional Theory ◽

X Ray ◽

Cluster 2 ◽

Cobalt Center

Synthesis, isolation, and structural characterization of unique metal rich diamagnetic cobaltaborane clusters are reported. They were obtained from reactions of monoborane as well as modified borohydride reagents with cobalt sources. For example, the reaction of [Cp*CoCl]2 with [LiBH4·THF] and subsequent photolysis with excess [BH3·THF] (THF = tetrahydrofuran) at room temperature afforded the 11-vertex tricobaltaborane nido-[(Cp*Co)3B8H10] (1, Cp* = η5-C5Me5). The reaction of Li[BH2S3] with the dicobaltaoctaborane(12) [(Cp*Co)2B6H10] yielded the 10-vertex nido-2,4-[(Cp*Co)2B8H12] cluster (2), extending the library of dicobaltadecaborane(14) analogues. Although cluster 1 adopts a classical 11-vertex-nido-geometry with one cobalt center and four boron atoms forming the open pentagonal face, it disobeys the Polyhedral Skeletal Electron Pair Theory (PSEPT). Compound 2 adopts a perfectly symmetrical 10-vertex-nido framework with a plane of symmetry bisecting the basal boron plane resulting in two {CoB3} units bridged at the base by two boron atoms and possesses the expected electron count. Both compounds were characterized in solution by multinuclear NMR and IR spectroscopies and by mass spectrometry. Single-crystal X-ray diffraction analyses confirmed the structures of the compounds. Additionally, density functional theory (DFT) calculations were performed in order to study and interpret the nature of bonding and electronic structures of these complexes.

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The siliconyl, boronyl, and iminoboryl ligands as analogues of the well-known carbonyl ligand: predicted reactivity towards dipolar cyclooligomerization in iron/cobalt carbonyl complexes

RSC Advances ◽

10.1039/c5ra01903f ◽

2015 ◽

Vol 5 (45) ◽

pp. 35558-35563 ◽

Cited By ~ 8

Author(s):

Zhong Zhang ◽

Liang Pu ◽

Qianshu Li ◽

R. Bruce King

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Carbonyl Complexes ◽

Carbonyl Ligand ◽

Cobalt Carbonyl ◽

Functional Theory ◽

Iron Cobalt ◽

Single Bonds

The Fe(CO)4(SiO), Co(CO)4(BO), and Co(CO)4(BNSiMe3), complexes akin to the well-known Fe(CO)5 are predicted by density functional theory to undergo exothermic oligomerization to give the oligomers containing SinOn/BnOn/B2N2 rings with single bonds.

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Synthesis and Characterization of the Germathioacid Chloride Coordinated by an N-Heterocyclic Carbene §

Inorganics ◽

10.3390/inorganics6030076 ◽

2018 ◽

Vol 6 (3) ◽

pp. 76 ◽

Cited By ~ 1

Author(s):

Yasunobu Egawa ◽

Chihiro Fukumoto ◽

Koichiro Mikami ◽

Nobuhiro Takeda ◽

Masafumi Unno

Keyword(s):

Carboxylic Acid ◽

Density Functional ◽

Dft Calculation ◽

Acid Chlorides ◽

Carboxylic Acid Chloride ◽

Functional Theory ◽

Nitrogen Ligands ◽

Bond Property ◽

Nitrogen Bonds

Carboxylic acid chlorides are useful substrates in organic chemistry. Many germanium analogues of carboxylic acid chloride have been synthesized so far. Nevertheless, all of the reported germathioacid chlorides use bidentate nitrogen ligands and contain germanium-nitrogen bonds. Our group synthesized germathioacid chloride, Ge(S)Cl{C6H3-2,6-Tip2}(Im-i-Pr2Me2), using N-heterocyclic carbene (Im-i-Pr2Me2). As a result of density functional theory (DFT) calculation, it was found that electrons are localized on sulfur, and the germanium-sulfur bond is a single bond with a slight double bond property.

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