Accessing Spin-Crossover Behaviour In Iron(II) Complexes Of N-Confused Scorpionate Ligands

The first examples of a class of N-confused tris(pyrazolyl)methane ‘scorpionate’ ligands have been prepared. The magnetic properties of their iron(II) tetrafluoroborate complexes are dictated by changing one substituent per ligand rather than three as is typical for normal scorpionate ligands

Reaction Chemistry of Silver(I) Trifluoromethanesulfonate Complexes of Nitrogen-Confused \u3cem\u3eC\u3c/em\u3e-Scorpionates

Two new C-scorpionate ligands with a bis(3,5-dimethylpyrazol-1-yl)methyl group bound to the 3 position of either an N-tosyl (TsL*) or an N–H pyrazole (HL*) ring have been prepared. The silver(I) complexes of these new ligands and the two previously reported analogous ligands with unsubstituted bis(pyrazol-1-yl)methyl groups (TsL and HL) in both 1:1 and 2:1 ligand/metal ratios were investigated to explore the effects of ligand sterics on their physical and chemical properties. The structurally characterized derivatives of the type [Ag(L)2](OTf) are four-coordinate, where the confused pyrazolyl is not bound to the metal. On the other hand, three 1:1 complexes [Ag(L)](OTf) had all pyrazolyls bound, while the μ–κ1,κ1-TsL derivative had an unbound confused pyrazolyl. The molecularity of the latter four ranged from polymeric to dimeric to monomeric in the solid with increasing steric bulk of the ligand. The utility of these complexes in stoichiometric ligand-transfer reactions and in styrene aziridination was demonstrated. Thus, tricarbonylmanganese(I) complexes were prepared as kinetically inert models for comparative solution diffusion NMR studies. Also, [Fe(HL)2](OTf)2 was prepared for similar reasons and to compare the effects of anion on spin-crossover properties

Securing the Strength of the Renewed NPT: China, the Linchpin Middle Kingdom

The consensus indefinite extension of the Nuclear Non-Proliferation Treaty (NPT) in 1995 and the more recent conclusion of a Comprehensive Test Ban Treaty. which was supported by all five of the world\u27s declared nuclear weapons states, allow for unprecedented optimism by nonproliferation experts regarding nuclear weapons proliferation curtailment and weapons reduction. These recent inroads into the accomplishment of NPT goals raise new questions. however. regarding the underlying commitment level of nuclear powers. China\u27s proliferation record, in particular. is marred with inconsistencies, but its current economic growth and increasingly nonisolationist policies may cause China to reconsider its past noncompliance with the NPT regime and help bring about long-term stability in South and Southeast Asia, culminating in a regional nuclear weapons-free zone. This Note explores China\u27s past role in nuclear proliferation and its reasons for not acceding to the NPT regime. Despite the ultimate success of the NPT regime to date, the Note discusses inherent weaknesses of the NPT. such as its inadequate enforcement and monitoring provisions, that could allow countries such as China to disregard their NPT obligations in the future and dismantle the NPT regime\u27s effectiveness. Because of such dismantling concerns, the Note addresses recent efforts by the United States to induce engagements by China in nonproliferation diplomacy. Although some U.S. tactics, such as economic sanctions, have achieved limited success, linking trade with nonproliferation policy is criticized as being both a short-term solution that fosters resentment and distrust as well as a solution that frustrates the potential demilitarization that a more developed and integrated market economy may encourage. The Note concludes by offering U.S. policy strategies to assist China in its compliance with the NPT and its potential leadership role under the NPT regime

Silver(I) and Copper(I) Complexes of Semi‐Bulky Nitrogen‐Confused C‐Scorpionates

Two new sterically demanding nitrogen‐confused C‐scorpionate ligands with a bis(3,5‐diisopropylpyrazol‐1‐yl)methyl group bound to the 3‐ position of a normal pyrazole (HLiPr2) or an N‐toluenesulfonyl pyrazole (TsLiPr2) have been prepared. Reactions between the ligands (xLiPr2) and silver trifluoromethanesulfonate, AgOTf, gave four new compounds of the types [Ag(xLiPr2)](OTf) (x = Ts, 1a; x = H, 2a) or [Ag(xLiPr2)2](OTf) (x = Ts, 1b; x = H, 2b) depending on the initial metal:ligand ratio. Similarly, the reactions with [Cu(CH3CN)4](PF6) produce four new compounds of the type [Cu(xLiPr2)(CH3CN)](PF6) (x = Ts, 3a; x = H, 4a) or [Cu(xLiPr2)2](PF6) (x = Ts, 3b; x = H, 4b). The solid‐state structures of four derivatives (1a·acetone, 3a, 3b·CH2Cl2, and 4b·2THF) were determined by single‐crystal X‐ray diffraction while all complexes were characterized in CH3CN solution by NMR spectroscopy and ESI(+) MS. The eight new complexes catalyze the aziridination of styrene. The copper complexes were generally (but not exclusively) more active catalysts than their silver counterparts

Selective Isomer Formation and Crystallization-Directed Magnetic Behavior in Nitrogen-Confused C-Scorpionate Complexes of Fe(O\u3csub\u3e3\u3c/sub\u3eSCF\u3csub\u3e3\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3e

The complex [Fe(HL*)2](OTf)2, 1, where HL* = bis(3,5-dimethylpyrazol-1-yl)(3-1H-pyrazole)methane, was prepared in order to compare its magnetic properties with those of the analogous parent complex, [Fe(HL)2](OTf)2, that lacks methyl groups on pyrazolyl rings and that undergoes spin crossover (SCO) from the low spin (LS) to the high spin (HS) form above room temperature. It was anticipated that this new semibulky derivative should favor the HS state and undergo SCO at a lower temperature range. During this study, six crystalline forms of 1 were prepared by controlling the crystallization conditions. Thus, when reagents are combined in CH3CN, an equilibrium mixture of cis and trans isomers is established that favors the latter below 311 K. The trans isomer can be isolated exclusively as a mixture of solvates, LS trans-1·2CH3CN and HS trans-1·4CH3CN, by cooling CH3CN solutions to −20 °C with the former being favored at high concentrations and short crystallization times. Subsequently, vapor diffusion of Et2O into CH3CN solutions of pure trans-1·2CH3CN gives solvate-free HS trans-1. Subjecting trans-1·2CH3CN to vacuum at room temperature gives microcrystalline trans-1·CH3CN, identified by elemental analysis and its distinct powder X-ray diffraction pattern. If an isomeric mixture of 1 is subject to room-temperature vapor diffusion, then a crystalline mixture of HS isomers cis-1 and trans-1 is obtained. Finally, slowly cooling hot acetonitrile solutions of isomeric mixtures of 1 to room temperature gives large prisms of HS co-1, a species with both cis and trans isomers in the unit cell. The complexes trans-1, trans-1·CH3CN, cis-1, and co-1 undergo SCO below 250 K while trans-1·xCH3CN (x = 2, 4) solvates do not undergo SCO before desolvation. Synopsis The complex, [Fe(HL*)2](OTf)2, 1, where HL* = bis(3,5-dimethylpyrazol-1-yl)(3-1H-pyrazole)methane, can be coerced to crystallize in one of four different forms from CH3CN solutions under normal laboratory conditions where each form has distinctive magnetic properties

Classical operators on the Hörmander algebras

We study the integration operator, the differentiation operator and more general differential operators on radial Fr´echet or (LB) H¨ormander algebras of entire functions. We analyze when these operators are power bounded, hypercyclic and (uniformly) mean ergodic.This research was partially supported by MEC and FEDER Project MTM2010-15200. The research of M. J. Beltran was also supported by grant F.P.U. AP2008-00604 and Programa de Apoyo a la Investigacion y Desarrollo de la UPV PAID-06-12, and the research of J. Bonet and C. Fernandez, by GVA under Project PROMETEOII/2013/013.Beltrán Meneu, MJ.; Bonet Solves, JA.; Fernández, C. (2015). Classical operators on the Hörmander algebras. Discrete and Continuous Dynamical Systems - Series A. 35(2):637-652. https://doi.org/10.3934/dcds.2015.35.637S63765235

Some results about diagonal operators on Köthe echelon spaces

[EN] Several questions about diagonal operators between Köthe echelon spaces are investigated: (1) The spectrum is characterized in terms of the Köthe matrices defining the spaces, (2) It is characterized when these operators are power bounded, mean ergodic or uniformly mean ergodic, and (3) A description of the topology in the space of diagonal operators induced by the strong topology on the space of all operators is given.This research was partially supported by MINECO Project MTM2016-76647-P and the grant PAID-01-16 of the Universitat Politècnica de València.Rodríguez-Arenas, A. (2019). Some results about diagonal operators on Köthe echelon spaces. Revista de la Real Academia de Ciencias Exactas Físicas y Naturales Serie A Matemáticas. 113(4):2959-2968. https://doi.org/10.1007/s13398-019-00663-yS295929681134Agathen, S., Bierstedt, K.D., Bonet, J.: Projective limits of weighted (LB)-spaces of continuous functions. Arch. Math. 92, 384–398 (2009)Albanese, A.A., Bonet, J., Ricker, W.J.: Mean ergodic operators in Fréchet spaces. Ann. Acad. Sci. Fenn. Math. 34(2), 401–436 (2009)Bennett, G.: Some elementary inequalities. Quart. J. Math. 38, 401–425 (1987)Bennett, G.: Factorizing the classical inequalities. Mem. Am. Math. Soc. (1996). https://doi.org/10.1090/memo/0576Bierstedt, K.D.: An introduction to locally convex inductive limits, Functional analysis and its applications (Nice, 1986), 35–133, ICPAM Lecture Notes. World Sci. Publishing, Singapore (1988)Bierstedt, K.D., Bonet, J.: Some aspects of the modern theory of Fréchet spaces. Rev. R. Acad. Cienc. Exactas Fís. Nat. Ser. A Mat. 97(2), 159–188 (2003)Bierstedt, K.D., Meise, R., Summers, W.H.: Köthe sets and Köthe sequence spaces, Functional Analysis, Holomorphy and Approximation Theory. North-Holland Math. Studies 71, 27–91 (1982)Bonet, J., Jordá, E., Rodríguez-Arenas, A.: Mean ergodic multiplication operators on weighted spaces of continuous functions. Mediterr. J. Math 15, 108 (2018)Crofts, G.: Concerning perfect Fréchet spaces and transformations. Math. Ann. 182, 67–76 (1969)Kellogg, C.N.: An extension of the Hausdorff–Young theorem. Michig. Math. J. 18, 121–127 (1971)Krengel, U.: Ergodic Theorems. de Gruyter, Berlin (1985)Meise, R., Vogt, D.: Introduction to Functional Analysis. Oxford University Press, New York (1997)Vasilescu, F.H.: Analytic Functional Calculus and Spectral Decompositions. D. Reidel Publ. Co., Dordrecht (1982)Wengenroth, J.: Derived Functors in Functional Analysis. Springer, Berlin (2003)Yosida, K.: Functional Analysis. Springer, Berlin (1980

Silicon nanoparticles with a polymer-derived carbon shell for improved lithium-ion batteries: Investigation into volume expansion, gas evolution, and particle fracture

Silicon (Si) and composites thereof, preferably with carbon (C), show favorable lithium (Li) storage properties at low potential, and thus hold promise for application as anode active materials in the energy storage area. However, the high theoretical specific capacity of Si afforded by the alloying reaction with Li involves many challenges. In this article, we report the preparation of small-size Si particles with a turbostratic carbon shell from a polymer precoated powder material. Galvanostatic charge/discharge experiments conducted on electrodes with practical loadings resulted in much improved capacity retention and kinetics for the Si/C composite particles compared to physical mixtures of pristine Si particles and carbon black, emphasizing the positive effect that the core−shell-type morphology has on the cycling performance. Using in situ differential electrochemical mass spectrometry, pressure, and acoustic emission measurements, we gain insights into the gassing behavior, the bulk volume expansion, and the mechanical degradation of the Si/C composite-containing electrodes. Taken together, our research data demonstrate that some of the problems of high-content Si anodes can be mitigated by carbon coating. Nonetheless, continuous electrolyte decomposition, particle fracture, and electrode restructuring due to the large volume changes during battery operation (here, ∼170% in the voltage range of 600−30 mV vs Li+/Li) remain as serious hurdles toward practical implementation

A Note on the Spectrum of Composition Operators on Spaces of Real Analytic Functions

[EN] In this paper the spectrum of composition operators on the space of real analytic functions is investigated. In some cases it is completely determined while in some other cases it is only estimated.The research of the authors was partially supported by MEC and FEDER Project MTM2013-43540-P and the work of of Bonet by the Grant GV Project Prometeo II/2013/013. The research of Domanski was supported by National Center of Science, Poland, Grant No. DEC-2013/10/A/ST1/00091.Bonet Solves, JA.; Domanski, P. (2017). A Note on the Spectrum of Composition Operators on Spaces of Real Analytic Functions. Complex Analysis and Operator Theory. 11(1):161-174. https://doi.org/10.1007/s11785-016-0589-5S161174111Belitskii, G., Lyubich, Y.: The Abel equation and total solvability of linear functional equations. Studia Math. 127, 81–97 (1998)Belitskii, G., Lyubich, Y.: The real analytic solutions of the Abel functional equation. Studia Math. 134, 135–141 (1999)Belitskii, G., Tkachenko, V.: One-Dimensional Functional Equations. Springer, Basel (2003)Belitskii, G., Tkachenko, V.: Functional equations in real analytic functions. Studia Math. 143, 153–174 (2000)Bonet, J., Domański, P.: Power bounded composition operators on spaces of analytic functions. Collect. Math. 62, 69–83 (2011)Bonet, J., Domański, P.: Hypercyclic composition operators on spaces of real analytic fucntions. Math. Proc. Cambridge Phil. Soc. 153, 489–503 (2012)Bonet, J., Domański, P.: Abel’s functional equation and eigenvalues of composition operators on spaces of real analytic functions. Integr. Equ. Oper. Theor. 81, 455–482 (2015). doi: 10.1007/s00020-014-2175-4Cartan, H.: Variétés analytiques réelles et variétés analytiques complexes. Bull. Soc. Math. France 85, 77–99 (1957)Domański, P.: Notes on real analytic functions and classical operators, Topics in Complex Analysis and Operator Theory (Winter School in Complex Analysis and Operator Theory, Valencia, February 2010), Contemporary Math. 561 (2012) 3–47. Amer. Math. Soc, Providence (2012)Domański, P., Goliński, M., Langenbruch, M.: A note on composition operators on spaces of real analytic functions. Ann. Polon. Mat. 103, 209–216 (2012)Domański, P., Langenbruch, M.: Composition operators on spaces of real analytic functions. Math. Nachr. 254–255, 68–86 (2003)Domański, P., Langenbruch, M.: Coherent analytic sets and composition of real analytic functions. J. reine angew. Math. 582, 41–59 (2005)Domański, P., Langenbruch, M.: Composition operators with closed image on spaces of real analytic functions. Bull. Lond. Math. Soc. 38, 636–646 (2006)Domański, P., Vogt, D.: The space of real analytic functions has no basis. Studia Math. 142, 187–200 (2000)Hörmander, L.: An Introduction to Complex Analysis in Several Variables. North Holland, Amsterdam (1986)Meise, R., Vogt, D.: Introduction to Functional Analysis. Clarendon, Oxford (1997)Smajdor, W.: On the existence and uniqueness of analytic solutions of the functional equation $$\varphi (z)=h(z,\varphi [f(z)])$$ φ ( z ) = h ( z , φ [ f ( z ) ] ) . Ann. Polon. Math. 19, 37–45 (1967