Thorium Mono- and Bis(imido) Complexes Made by Reprotonation of <i>cyclo</i>-Metalated Amides

Molecules containing actinide–nitrogen multiple bonds are of current interest as simple models for new actinide nitride nuclear fuels, and for their potential for the catalytic activation of inert hydrocarbon C–H bonds. Complexes with up to three uranium–nitrogen double bonds are now being widely studied, yet those with one thorium–nitrogen double bond are rare, and those with two are unknown. A new, simple mono­(imido) thorium complex and the first bis­(imido) thorium complex, K­[Th­(NAr)­N″₃] and K₂[Th­(NAr)₂N″₂], are readily made from insertion reactions (Ar = aryl, N″ = N­(SiMe₃)₂) into the Th–C bond of the cyclometalated thorium amides [ThN″₂(N­(SiMe₃)­(SiMe₂CH₂))] and K­[ThN″(N­(SiMe₃)­(SiMe₂CH₂))₂]. X-ray and computational structural analyses show a “transition-metal-like” <i>cis</i>-bis­(imido) geometry and polarized ThN bonds with twice the Wiberg bond order of the formally single Th–N bond in the same molecule

Thorium Mono- and Bis(imido) Complexes Made by Reprotonation of <i>cyclo</i>-Metalated Amides

Molecules containing actinide–nitrogen multiple bonds are of current interest as simple models for new actinide nitride nuclear fuels, and for their potential for the catalytic activation of inert hydrocarbon C–H bonds. Complexes with up to three uranium–nitrogen double bonds are now being widely studied, yet those with one thorium–nitrogen double bond are rare, and those with two are unknown. A new, simple mono­(imido) thorium complex and the first bis­(imido) thorium complex, K­[Th­(NAr)­N″₃] and K₂[Th­(NAr)₂N″₂], are readily made from insertion reactions (Ar = aryl, N″ = N­(SiMe₃)₂) into the Th–C bond of the cyclometalated thorium amides [ThN″₂(N­(SiMe₃)­(SiMe₂CH₂))] and K­[ThN″(N­(SiMe₃)­(SiMe₂CH₂))₂]. X-ray and computational structural analyses show a “transition-metal-like” <i>cis</i>-bis­(imido) geometry and polarized ThN bonds with twice the Wiberg bond order of the formally single Th–N bond in the same molecule

Selective Oligomerization and [2 + 2 + 2] Cycloaddition of Terminal Alkynes from Simple Actinide Precatalysts

A catalyzed conversion of terminal alkynes into dimers, trimers, and trisubstituted benzenes has been developed using the actinide amides U­[N­(SiMe₃)₂]₃ (<b>1</b>) and [(Me₃Si)₂N]₂An­[κ²-(<i>N</i>,<i>C</i>)-CH₂Si­(CH₃)­N­(SiMe₃)] (An = U (<b>2</b>), Th (<b>3</b>)) as precatalysts. These complexes allow for preferential product formation according to the identity of the metal and the catalyst loading. While these complexes are known as valuable precursors for the preparation of various actinide complexes, this is the first demonstration of their use as catalysts for C–C bond forming reactions. At high uranium catalyst loading, the cycloaddition of the terminal alkyne is generally preferred, whereas at low loadings, linear oligomerization to form enynes is favored. The thorium metallacycle produces only organic enynes, suggesting the importance of the ability of uranium to form stabilizing interactions with arenes and related π-electron-containing intermediates. Kinetic, spectroscopic, and mechanistic data that inform the nature of the activation and catalytic cycle of these reactions are presented

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

Thermally Stable Uranium Dinitrogen Complex with Siloxide Supporting Ligands

A new dinitrogen adduct of a homoleptic uranium tris­(siloxide) complex, [U­{OSi­(Mes)₃}₃]₂(μ-η²:η²-N₂), is reported. Synthesis of the ¹⁵N-labeled isotopomer and Raman spectroscopy confirm the reductive activation of N₂ to a (N₂)^2– dianion. The ¹⁵N NMR shift of the ¹⁵N₂-labeled isotopomer is also reported. Crystallographic characterization shows a side-on (N₂)^2– coordinated in either an eclipsed or staggered conformation in different crystals. The U–N₂–U complex is stable to vacuum and shows high thermal stability, retaining the formally reduced dinitrogen at 100 °C. The parent three-coordinate uranium­(III) [U­{OSi­(Mes)₃}₃] could not be isolated in our hands, with N₂-free syntheses affording only uranium­(IV) compounds. The rational synthesis and full characterization of two such U­(IV) byproducts, [U­{OSi­(Mes)₃}­{N­(SiMe₃)₂}₃] and [U­{OSi­(Mes)₃}₄], is also reported

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

Inter- versus Intramolecular Structural Manipulation of a Dichromium(II) Pacman Complex through Pressure Variation

The effect of pressure on the intranuclear M···M separation and intermolecular secondary interactions in the dinuclear chromium Pacman complex [Cr₂(L)]­(C₆H₆) was evaluated because this compound contains both a short Cr···Cr separation and an exogenously bound molecule of benzene in the solid state. The electronic structure of [Cr₂(L)] was determined by electron paramagnetic resonance spectroscopy, SQUID magnetometry, and density functional theory calculations and shows a diamagnetic ground state through antiferromagnetic exchange, with no evidence for a Cr–Cr bond. Analysis of the solid-state structures of [Cr₂(L)]­(C₆H₆) at pressures varying from ambient to 3.0 GPa shows little deformation in the Cr···Cr separation, i.e., no Cr–Cr bond formation, but instead a significantly increased interaction between the exogenous arene and the chromium iminopyrrolide environment. It is therefore apparent from this analysis that [Cr₂(L)] would be best exploited as a rigid chemical synthon, with pressure regulation being used to mediate the approach and secondary interactions of possible substrates

Inter- versus Intramolecular Structural Manipulation of a Dichromium(II) Pacman Complex through Pressure Variation

The effect of pressure on the intranuclear M···M separation and intermolecular secondary interactions in the dinuclear chromium Pacman complex [Cr₂(L)]­(C₆H₆) was evaluated because this compound contains both a short Cr···Cr separation and an exogenously bound molecule of benzene in the solid state. The electronic structure of [Cr₂(L)] was determined by electron paramagnetic resonance spectroscopy, SQUID magnetometry, and density functional theory calculations and shows a diamagnetic ground state through antiferromagnetic exchange, with no evidence for a Cr–Cr bond. Analysis of the solid-state structures of [Cr₂(L)]­(C₆H₆) at pressures varying from ambient to 3.0 GPa shows little deformation in the Cr···Cr separation, i.e., no Cr–Cr bond formation, but instead a significantly increased interaction between the exogenous arene and the chromium iminopyrrolide environment. It is therefore apparent from this analysis that [Cr₂(L)] would be best exploited as a rigid chemical synthon, with pressure regulation being used to mediate the approach and secondary interactions of possible substrates