Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters

Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H₄<b>L</b> have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca­(THF)₂­(H₂<b>L</b>^<b>1</b>), Ca₂(THF)₂­(μ-THF)­(<b>L</b>^<b>1</b>), and Ca₂(THF)₄­(<b>L</b>^<b>2</b>), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca₂(py)₅(<b>L</b>^<b>3</b>). The mononuclear calcium complex Ca­(THF)₂­(H₂<b>L</b>^<b>1</b>) reacts with various equivalents of LiN­(SiMe₃)₂ to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca₂(THF)₂­(μ-THF)­(<b>L</b>^<b>1</b>), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations

Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters

Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H₄<b>L</b> have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca­(THF)₂­(H₂<b>L</b>^<b>1</b>), Ca₂(THF)₂­(μ-THF)­(<b>L</b>^<b>1</b>), and Ca₂(THF)₄­(<b>L</b>^<b>2</b>), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca₂(py)₅(<b>L</b>^<b>3</b>). The mononuclear calcium complex Ca­(THF)₂­(H₂<b>L</b>^<b>1</b>) reacts with various equivalents of LiN­(SiMe₃)₂ to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca₂(THF)₂­(μ-THF)­(<b>L</b>^<b>1</b>), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations

Rational Synthesis and Electronic Structure of Functionalized Trinuclear Pd Metal Sheet Sandwich Complexes

In this article we present the rational synthesis and full characterization of molecular Pd₃ clusters sandwiched by imidazolium- and pyridinium-functionalized cycloheptatrienide ligands, of general formula [Pd₃Br₃(C₇H₆R)₂]⁺. From functionalized η³-cycloheptatrienide Pd complexes as starting materials, PdBr₂(η³-C₇H₆R), a number of synthetic routes were tested and a generally applicable strategy was developed on the basis of the formation of dimeric “preclusters”, [{PdBr­(η³-C₇H₆R)}₂(μ-Br)]⁺, which exhibit a Pd–Pd interaction. Spectroscopic and electrochemical results indicate a noninteger, common oxidation state of Pd in the trinuclear clusters, and crystallographic analysis reveals distinct differences in the binding properties of the Pd atoms in the solid state, suggesting that in certain environments there are even two discernible oxidation states, which is supported by computational analysis of the charge distribution

Rational Synthesis and Electronic Structure of Functionalized Trinuclear Pd Metal Sheet Sandwich Complexes

In this article we present the rational synthesis and full characterization of molecular Pd₃ clusters sandwiched by imidazolium- and pyridinium-functionalized cycloheptatrienide ligands, of general formula [Pd₃Br₃(C₇H₆R)₂]⁺. From functionalized η³-cycloheptatrienide Pd complexes as starting materials, PdBr₂(η³-C₇H₆R), a number of synthetic routes were tested and a generally applicable strategy was developed on the basis of the formation of dimeric “preclusters”, [{PdBr­(η³-C₇H₆R)}₂(μ-Br)]⁺, which exhibit a Pd–Pd interaction. Spectroscopic and electrochemical results indicate a noninteger, common oxidation state of Pd in the trinuclear clusters, and crystallographic analysis reveals distinct differences in the binding properties of the Pd atoms in the solid state, suggesting that in certain environments there are even two discernible oxidation states, which is supported by computational analysis of the charge distribution

Isocyanide and Phosphine Oxide Coordination in Binuclear Chromium Pacman Complexes

The new binuclear chromium Pacman complex [Cr₂(L)] of the Schiff base pyrrole macrocycle H₄L has been synthesized and structurally characterized. Addition of isocyanide, CNR (R = xylyl, ^tBu), or triphenylphosphine oxide donors to [Cr₂(L)] gives contrasting chemistry with the formation of the new coordination compounds [Cr₂(μ-CNR)­(L)], in which the isocyanides bridge the two Cr­(II) centers, and [Cr₂(OPPh₃)₂(L)], a Cr­(II) phosphine oxide adduct with the ligands exogenous to the cleft

Role of the Meso Substituent in Defining the Reduction of Uranyl Dipyrrin Complexes

The uranyl complex UVIO2Cl(LMes) of the redox-active, acyclic dipyrrin–diimine anion LMes– [HLMes = 1,9-di-tert-butyl-imine-5-(mesityl)dipyrrin] is reported, and its redox property is explored and compared with that of the previously reported UVIO2Cl(LF) [HLF = 1,9-di-tert-butyl-imine-5-(pentafluorophenyl)dipyrrin] to understand the influence of the meso substituent. Cyclic voltammetry, electron paramagnetic resonance spectroscopy, and density functional theory studies show that the alteration from an electron-withdrawing meso substituent to an electron-donating meso substituent on the dipyrrin ligand significantly modifies the stability of the products formed after reduction. For UVIO2Cl(LMes), the formation of a diamond-shaped, oxo-bridged uranyl(V) dimer, [UVO2(LMes)]2 is seen, whereas in contrast, for UVIO2Cl(LF), only ligand reduction occurs. Computational modeling of these reactions shows that while ligand reduction followed by chloride dissociation occurs in both cases, ligand-to-metal electron transfer is favorable for UVIO2Cl(LMes) only, which subsequently facilitates uranyl(V) dimerization

The Influence of the Hofmeister Bias and the Stability and Speciation of Chloridolanthanates on Their Extraction from Chloride Media

<p>The possibility of recovering rare earth elements from solutions containing their chloridometalate anions [LnCl<i>_x</i>]^{(<i>x</i>−3)−} via the process: LnCl<i>_x</i>^{(<i>x</i>−3)−} + (<i>x</i> − 3)<i>L</i>_org + (<i>x</i>–3)H⁺ ⇌ [(LH)<i>_x</i>₋₃LnCl<i>_x</i>]_org has been tested using 2-(1,3-bis(hexylamino)-1,3-dioxopropan-2-yl)-4,6-di-<i>tert</i>-butylpyridine (PMA), tri-<i>n-</i>butylphosphate (TBP), and tri-<i>n</i>-octylamine (TOA), which are known to be strong extractants for transition metal chloridometalates. While DFT calculations indicate that the formation of the neutral assembly [(PMAH)₃LaCl₆] in the gas phase is favorable, no uptake of La(III) from 6 M HCl by toluene solutions of PMA (or of TBP or TOA) was observed in solvent extraction experiments. Successful uptake of the [PtCl₆]²⁻ dianion by PMA and the failure to extract the [IrCl₆]³⁻ trianion under the same conditions indicate that the higher hydration energy of the latter makes transfer to the toluene solution less favorable and that this militates against extraction of La(III) chlorido complexes carrying charges of −3 or larger in which all the inner-sphere water molecules have been replaced. Computational results confirm literature observations that, in contrast to transition metal trications, formation of REE metalate anions such as [LnCl<i>_x</i>]^{(<i>x</i>−3)−} is not very favorable, particularly so for chloride, compared with nitrato or sulfato systems. Also, they indicate that the formation of <i>outer-sphere</i> assemblies such as {[La(H₂O)₉]·<i>x</i>Cl} in which water ligands are retained in the inner sphere, H-bonded to anions, is more stable than <i>inner-sphere</i> complexes containing an equivalent number of anions. The high level of hydration of such species disfavors their transfer into nonpolar water-immiscible solvents. It is unlikely that recovery of [LnCl<i>_x</i>]^{(<i>x</i>−3)−} from acidic solutions can be achieved efficiently using currently available anion exchange extractants operating in a “pH-swing” process. Receptors giving very high binding energies to chloridolanthanates will be needed to offset the high dehydration energies required.</p

Macrocyclic Platforms for the Construction of Tetranuclear Oxo and Hydroxo Zinc Clusters

The design of ligands that can act as platforms for the controlled, “bottom-up” synthesis of transition-metal clusters is a promising approach to accessing enzymatic mimics and new small-molecule reaction chemistry. This approach is exemplified here through the coordination chemistry of two compartmental Schiff-base calixpyrroles (H₄L) that usually act as dinucleating ligands for transition metals. While reactions between H₄L and Zn­{N­(SiMe₃)₂}₂ form the expected dinuclear Zn “Pacman” complexes Zn₂(L), reactions with ZnEt₂ result in the tetranuclear Zn alkyl complexes Zn₄Et₄(THF)₄(L), in which open, “bowl-shaped” structures are adopted due to the flexibility of the macrocyclic platform. The outcome of hydrolysis reactions of these tetranuclear complexes is found to depend on the macrocyclic cavity size, with the smaller macrocycle favoring oxo formation in Zn₄(μ₄-O)­Et₂(L) and the larger macrocycle favoring complete hydrolysis to form the hydroxide-bridged cluster Zn₄(μ₂-OH)₄(L). This latter complex reacts with carbon dioxide at elevated temperature, re-forming the free macrocycle H₄L and eliminating ZnCO₃

Näyttöön perustuva toiminta Kuopion yliopistollisessa sairaalassa

Näyttöön perustuvan toiminnan edistäminen nähdään keskeisenä kehittämisalueena hoitotyössä kansainvälisesti ja kansallisesti. Tutkimuksen tarkoituksena oli kuvata Kuopion yliopistollisen sairaalan (KYS) osastotyössä työskentelevien hoitotyöntekijöiden näkemyksiä näyttöön perustuvasta toiminnasta (NPT) käytännössä. Tutkimuksen tarkoituksena oli kuvata hoitotyöntekijöiden asenteita ja käsityksiä osaamisestaan näyttöön perustuvan hoitotyön toteuttamiseen. Tutkimuksen tavoitteena oli tuottaa tutkimustietoa NPT nykytilanteesta KYSissä, jota voidaan hyödyntää sen kehittämisessä ja henkilökunnan kouluttamisessa. Kvantitatiivinen tutkimus toteutettiin Webropol-verkkokyselynä. Kokonaisotannalla kyselyn saivat kaikki kliinistä hoitotyötä tekevät hoitotyöntekijät 34:sta työyksiköstä. Aineisto kerättiin strukturoidulla kyselylomakkeella, jonka kysymykset muodostuivat EBPQ- ja Attitudes to Evidence-Based Practice –mittareiden suomeksi käännetyistä kysymyksistä. Aineisto analysoitiin tilastollisin menetelmin. Tutkimukseen osallistuneista (n=94) suurin osa arvioi toimintansa perustuvan yli 60 %:sesti näyttöön. Asenteet NPT kohtaan ovat suurilta osin myönteisiä, kuitenkin työympäristössä tapahtuvat muutokset ja työkiire tuovat haasteita uuden tutkimustiedon käyttöön. Ajallisten resurssien lisäksi NPT tiedot ja taidot ovat puutteellisia. Tutkimusosaaminen ja näytön kriittinen arviointi arvioitiin heikoimmaksi osaamisalueeksi. Vastaajien koulutustaustalla oli tilastollisesti merkitsevä yhteys arvioituun NPT osaamiseen. Hoitotyöntekijöiden asenne NPT kohtaan on positiivista ja se nähdään ammatillisen toiminnan perustana. NPT kehittämiseksi tarvitaan koulutuksellista ja kollegiaalista tukea, mutta myös riittävät henkilöstöresurssit ja aikaa sen toteuttamiseen.Promoting evidence-based practice (EBP) is a key development area in nursing on the international and national level. The purpose of the study was to describe the views on how nursing staff use EBP in practical work at the Kuopio University Hospital (KUH). The aim of the study was to describe nursing professionals’ attitudes towards and perceptions of their competence in providing evidence-based nursing. The aim of the study was to produce research data on the current EBP situation in KUH in order to use it in EBP development and staff training. Quantitative research was conducted by using an online survey provided by the Webropol software. Based on total sampling, the questionnaire was sent to all nurses doing clinical nursing in 34 working units. The material was collected with a structured questionnaire in which the questions came from the EBPQ and Attitudes to Evidence-Based Practice questionnaires. The data was analysed using statistical methods. Most of the participants in the survey (n = 94) estimated that over 60 per cent of their work operations were based on evidence. Attitudes towards EBP were mostly positive, but changes in the working environment and time pressures brought challenges to the use of new research information. Critical evaluation of research-based evidence was deemed to be the weakest competence area. The respondents' educational background had a statistically significant connection to the evaluated competence of evidence-based conduct. The attitudes towards evidence-based nursing were positive and it was seen as the basis for professional conduct. In order to develop EBP competence, more educational and collegial support is needed, but also sufficient staff resources and time to develop and implement evidence-based practices

New Chemistry from an Old Reagent: Mono- and Dinuclear Macrocyclic Uranium(III) Complexes from [U(BH₄)₃(THF)₂]

A new robust and high-yielding synthesis of the valuable U^III synthon [U­(BH₄)₃(THF)₂] is reported. Reactivity in ligand exchange reactions is found to contrast significantly to that of uranium triiodide. This is exemplified by the synthesis and characterization of azamacrocyclic U^III complexes, including mononuclear [U­(BH₄)­(L)] and dinuclear [Li­(THF)₄]­[{U­(BH₄)}₂(μ-BH₄)­(L^Me)] and [Na­(THF)₄]­[{U­(BH₄)}₂(μ-BH₄)­(L^A)­(THF)₂]. The structures of all complexes have been determined by single-crystal X-ray diffraction and display two new U^III₂(BH₄)₃ motifs