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Rational Design, Stabilities and Nonlinear Optical Properties of Non-Conventional Transition Metalides; New Entry into Nonlinear Optical Materials. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16093447. [PMID: 37176328 PMCID: PMC10180138 DOI: 10.3390/ma16093447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/14/2023] [Accepted: 04/20/2023] [Indexed: 05/15/2023]
Abstract
Electronic and nonlinear optical properties of endohedral metallofullerenes are presented. The endohedral metallofullerenes contain transition metal encapsulated in inorganic fullerenes X12Y12 (X = B, Al & Y = N, P). The endohedral metallofullerenes (endo-TM@X12Y12) possess quite interesting geometric and electronic properties, which are the function of the nature of the atom and the size of fullerene. NBO charge and frontier molecular orbital analyses reveal that the transition metal encapsulated Al12N12 fullerenes (endo-TM@Al12N12) are true metalides when the transition metals are Ni, Cu and Zn. Endo-Cr@Al12N12 and endo-Co@Al12N12 are at the borderline between metalides and electrides with predominantly electride characteristics. The other members of the series are excess electron systems, which offer interesting electronic and nonlinear optical properties. The diversity of nature possessed by endo-TM@Al12N12 is not prevalent for other fullerenes. Endo-TM@Al12P12 are true metalides when the transition metals are (Cr-Zn). HOMO-LUMO gaps (EH-L) are reduced significantly for these endohedral metallofullerenes, with a maximum percent decrease in EH-L of up to 70%. Many complexes show odd-even oscillating behavior for EH-L and dipole moments. Odd electron species contain large dipole moments and small EH-L, whereas even electron systems have the opposite behavior. Despite the decrease in EH-L, these systems show high kinetic and thermodynamic stabilities. The encapsulation of transition metals is a highly exergonic process. These endo-TM@X12Y12 possess remarkable nonlinear optical response in which the first hyperpolarizability reaches up to 2.79 × 105 au for endo-V@Al12N12. This study helps in the comparative analysis of the potential nonlinear optical responses of electrides, metalides and other excess electron systems. In general, the potential nonlinear optical response of electrides is higher than metalides but lower than those of simple excess electron compounds. The higher non-linear optical response and interesting electronic characteristics of endo-TM@Al12N12 complexes may be promising contenders for potential NLO applications.
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The Sodium Anion Is Strongly Perturbed in the Condensed Phase Even Though It Appears Like a Free Ion in Nuclear Magnetic Resonance Experiments. J Phys Chem Lett 2020; 11:843-850. [PMID: 31928009 DOI: 10.1021/acs.jpclett.9b03432] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Solvated sodium anions (Na-) were thought to behave essentially like isolated gas-phase ions that interact only weakly with their environments. For example, 23Na NMR signals for solvated Na- are very sharp, despite the potential for strong quadrupolar broadening. The sharp NMR signals appear to indicate a nearly spherical electron density of the ion. For the present study, ab initio molecular dynamics simulations and quadrupolar relaxation rate calculations were carried out for the Na-/Na+ [2.2.2]cryptand system solvated in methylamine, followed by detailed analyses of the electric field gradient at the sodium nuclei. It is found that Na- does not behave like a quasi-free ion interacting only weakly with its environment. Rather, the filled 3s shell of Na- interacts weakly with the ion's own core and the nucleus, causing Na- to appear in NMR experiments like a free ion.
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Thermodynamic cycles of the alkali metal–ligand complexes central to electride formation. Phys Chem Chem Phys 2017; 19:12816-12825. [DOI: 10.1039/c7cp00882a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Alkali metal–ligand complexes are the building blocks of the exotic organic alkalide and electride materials.
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The alkali metals: 200 years of surprises. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0174. [PMID: 25666067 DOI: 10.1098/rsta.2014.0174] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Alkali metal compounds have been known since antiquity. In 1807, Sir Humphry Davy surprised everyone by electrolytically preparing (and naming) potassium and sodium metals. In 1808, he noted their interaction with ammonia, which, 100 years later, was attributed to solvated electrons. After 1960, pulse radiolysis of nearly any solvent produced solvated electrons, which became one of the most studied species in chemistry. In 1968, alkali metal solutions in amines and ethers were shown to contain alkali metal anions in addition to solvated electrons. The advent of crown ethers and cryptands as complexants for alkali cations greatly enhanced alkali metal solubilities. This permitted us to prepare a crystalline salt of Na(-) in 1974, followed by 30 other alkalides with Na(-), K(-), Rb(-) and Cs(-) anions. This firmly established the -1 oxidation state of alkali metals. The synthesis of alkalides led to the crystallization of electrides, with trapped electrons as the anions. Electrides have a variety of electronic and magnetic properties, depending on the geometries and connectivities of the trapping sites. In 2009, the final surprise was the experimental demonstration that alkali metals under high pressure lose their metallic character as the electrons are localized in voids between the alkali cations to become high-pressure electrides!
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Novel supramolecular catalysis in the controlled synthesis of polymers and block copolymers. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19961070122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Alkali metals in ethylenediamine: a computational study of the optical absorption spectra and NMR parameters of [M(en)3(δ+)·M(δ-)] ion pairs. J Am Chem Soc 2011; 133:4829-39. [PMID: 21366240 DOI: 10.1021/ja1085244] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The optical absorption spectra of alkali metals in ethylenediamine have provided evidence for a third oxidation state, -1, of all of the alkali metals heavier than lithium. Experimentally determined NMR parameters have supported this interpretation, further indicating that whereas Na(-) is a genuine metal anion, the interaction of the alkali anion with the medium becomes progressively stronger for the larger metals. Herein, first-principles computations based upon density functional theory are carried out on various species which may be present in solutions composed of alkali metals and ethylenediamine. The energies of a number of hypothetical reactions computed with a continuum solvation model indicate that neither free metal anions, M(-), nor solvated electrons are the most stable species. Instead, [Li(en)(3)](2) and [M(en)(3)(δ+)·M(δ-)] (M = Na, K, Rb, Cs) are predicted to have enhanced stability. The M(en)(3) complexes can be viewed as superalkalis or expanded alkalis, ones in which the valence electron density is pulled out to a greater extent than in the alkali metals alone. The computed optical absorption spectra and NMR parameters of the [Li(en)(3)](2) superalkali dimer and the [M(en)(3)(δ+)·M(δ-)] superalkali-alkali mixed dimers are in good agreement with the aforementioned experimental results, providing further evidence that these may be the dominant species in solution. The latter can also be thought of as an ion pair formed from an alkali metal anion (M(-)) and solvated cation (M(en)(3)(+)).
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Electrides, Negatively Charged Metal Ions, and Related Phenomena. PROGRESS IN INORGANIC CHEMISTRY 2007. [DOI: 10.1002/9780470166338.ch4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Correlation of the Structure and Properties of Alkalides and Electrides That Contain Cryptands or Crown Ethers. J COORD CHEM 2007. [DOI: 10.1080/00958978808080696] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Kinetics of the hydrated electron disappearance in concentrated aqueous alkali solutions. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/00337577208232577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
A brief history of substances containing s,p- and d-block metals in negative oxidation states is described. A classification of these species and discussions of formal oxidation state assignments for low-valent transition metals in complexes are included, along with comments on the innocent and noninnocent character of ligands in metalates. Syntheses of highly reduced carbonyl complexes formally containing transition metals in their lowest known oxidation states of III- and IV- are discussed. Atmospheric-pressure syntheses of early-transition-metal carbonyls involving alkali-metal polyarene-mediated reductions of non-carbonyl precursors have been developed. In the absence of carbon monoxide, these reactions afford homoleptic polyarenemetalates, including the initial species containing three aromatic hydrocarbons bound to one metal. In several instances, these metalates function as useful synthons for "naked" spin-paired atomic anions of transition metals.
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Mapping CTTS dynamics of Na−in tetrahydrofurane with ultrafast multichannel pump–probe spectroscopy. Phys Chem Chem Phys 2006; 8:2599-609. [PMID: 16738713 DOI: 10.1039/b602933g] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using multichannel femtosecond spectroscopy we have followed Na- charge transfer to solvent (CTTS) dynamics in THF solution. Absorption of the primary photoproducts in the visible, resolved here for the first time, consists of an asymmetric triplet centered at 595 nm, which we assign to a metastable incompletely solvated neutral atomic sodium species. Decay of this feature within approximately 1 ps to a broad and structureless solvated neutral is accompanied by broadening and loss of spectral detail. Kinetic analysis shows that both the spectral structure and the decay of this band are independent of the excitation photon frequency in the range 400-800 nm. With different pump-probe polarizations the anisotropy in transient transmission has been charted and its variation with excitation wavelength surveyed. The anisotropies are assigned to the reactant bleach, indicating that due to solvent-induced symmetry breaking, the CTTS absorption band of Na- is made up of discreet orthogonally polarized sub bands. None of the anisotropy in transient absorption could be associated with the photoproduct triplet band even at the earliest measurable time delays. Along with the documented differences in the spatial distribution of ejected electrons across the tested excitation wavelength range, these results lead us to conclude that photoejection is extremely rapid, and that loss of correlations between the departing electron and its neutral core is faster than our time resolution of approximately 60 fs.
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Role of Cation Complexants in the Synthesis of Alkalides and Electrides. ADVANCES IN INORGANIC CHEMISTRY 2006. [DOI: 10.1016/s0898-8838(06)59006-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
An electride has been synthesized that is stable to auto-decomposition at room temperature. The key was the theoretically directed synthesis of a per-aza analogue of cryptand[2.2.2] in which each of the linking arms contains a piperazine ring. This complexant was designed to provide strong complexation of Na+ via pre-organization of a "crypt" that contains eight nonreducible tertiary amine nitrogens. The structure and properties indicate that, as with other electrides, the "anions" are electrons trapped in the cavities formed by close-packing of the complexed cations. The isostructural sodide, with Na- anions in the cavities, is also stable at and above room temperature.
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Solvent Induced Symmetry Breaking and Relaxation Following Charge Transfer to Solvent Excitation of Na- in Tetrahydrofuran. J Phys Chem A 2003. [DOI: 10.1021/jp014331p] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nucleophilic substitution and electron transfer in the ring-opening reactions of β-lactones: A short review. J Heterocycl Chem 2001. [DOI: 10.1002/jhet.5570380602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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How Does the Solvent Control Electron Transfer? Experimental and Theoretical Studies of the Simplest Charge Transfer Reaction. J Phys Chem B 2001. [DOI: 10.1021/jp011150e] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Photoelectrons in Rb/THF Solution: Spectral Dependence of Photodetachment Cross-Section. J Phys Chem A 2001. [DOI: 10.1021/jp003077i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Characterization of potassium and sodium-potassium alloy solutions containing metal anions and complexed cations by means of NMR and ESR techniques. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000; 56A:1257-1265. [PMID: 10888430 DOI: 10.1016/s1386-1425(99)00216-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The influence of a complexing agent, kind of solvent and temperature on the stability and ionic composition of potassium and sodium-potassium alloy solutions containing metal anions and complexed cations as well as solvated electrons are discussed basing on the analysis of alkali metal NMR and ESR spectra. Surprisingly it seems that the stability of metal solutions in tetrahydrofuran at ambient temperature is inversely proportional to the durability of K+ complex in the case of five studied ligands. The most stable metal solutions were obtained using 15-crown-5. It was shown that the characteristic blue colour of metal solutions is not connected with the presence of solvated electrons but with metal anions.
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Direct observation of charge-transfer-to-solvent (CTTS) reactions: Ultrafast dynamics of the photoexcited alkali metal anion sodide (Na−). J Chem Phys 2000. [DOI: 10.1063/1.481563] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Interaction of light with Na+ C222.Na−. A laser flash photolysis and EPR investigation. Chem Phys Lett 1990. [DOI: 10.1016/0009-2614(90)85272-e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
Electrides are ionic compounds that have alkali metal cations complexed by a crown ether or cryptand, with trapped electrons as counterions. The crystal structures and properties of two electrides illustrate the diversity that is encountered. One Cs(+) (18-crown-6)(z)e(-), has relatively isolated, trapped electrons apparently centered at each anionic site. It has a low conductivity consistent with electron localization, with an activation energy for conductivity of at least 0.45 electron volt. The other, K(+) (cryptand[2.2.2])e(-), has electron pairs trapped in an elongated cavity in a singlet ground state, but there is also a thermally accessible paramagnetic state available. This electride is much more conducting, with an activation energy of only 0.02 electron volt.
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Alkali metal solutions. Effect of cryptands on solubility and spectra in tetrahydrofuran, dioxane and toluene. J Organomet Chem 1982. [DOI: 10.1016/s0022-328x(00)81206-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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The Electronic Properties of Metal Solutions in Liquid Ammonia and Related Solvents. ADVANCES IN INORGANIC CHEMISTRY 1982. [DOI: 10.1016/s0898-8838(08)60140-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Electrode reaction schemes and standard potential of solvated electron electrode in methylamine. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0022-0728(81)80288-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ion-pairing and electron spin resonance spectra of solutions of alkali metals in polar solvents. Chem Phys Lett 1979. [DOI: 10.1016/0009-2614(79)80512-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Pulse radiolysis of alkali metal cations in isopropylamine: Correlation of optical absorption spectra with electron spin resonance data. Chem Phys 1976. [DOI: 10.1016/0301-0104(76)80067-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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L�sungen von Alkalimetallen in �thern in Anwesenheit von hexamethylphosphors�uretriamid. MONATSHEFTE FUR CHEMIE 1972. [DOI: 10.1007/bf00905188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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