2,085 research outputs found
Structural elaboration of the surprising ortho-zincation of benzyl methyl ether
Breaking with convention, the reaction of the sodium zincate, [(TMEDA)Na(Ό-TMP)(Ό-tBu)Zn(tBu)] with benzyl methyl ether (PhCH2OMe) produces exclusively an ortho-zincated intermediate [(TMEDA)Na(Ό-TMP)(Ό-C6H4CH2OMe)Zn(tBu)] instead of the expected 'thermodynamic' α-metallated product
Diisopropylamide and TMP turbo-grignard reagents : a structural rationale for their contrasting reactivities
A neutral dimeric molecule in crystal form, the diisopropylamido turbo-Grignard reagent "(iPr2N)MgClâ
LiCl" (see structure; blue N, red O, green Mg, yellow Cl, black C) separates into several charged ate species in dynamic exchange with each other in THF solution as determined by a combination of EXSY and DOSY NMR studies
How to be a good professional: existentialist continuing professional development (CPD)
This article reflects on the construct and practice of continuing professional development (CPD) and its significance for the professional careers workforce. The article presents the idea of the CPD triad and considers how professional bodies, employers and individuals can each benefit from a practitioner's ongoing commitment to continuing professional development. The tension between the practitioner's quest for lifelong learning is set against professional body demands, leading to the conclusion that these are not necessarily mutually exclusive. Consideration is given to propositional, practical and procedural knowledge, and to overall competence. The article explores an existentialist approach to professional learning, and concludes that, along with personal agency, this could usefully be adopted by career practitioners to weather turbulent times
Multistep self-assembly of heteroleptic magnesium and sodium-magnesium benzamidinate complexes
Reaction of the magnesium bis-alkyl Mg(CH2SiMe3)(2) and the sodium amide NaHMDS (where HMDS = N(SiMe3)(2)) with benzonitrile yields the homometallic heteroleptic complex [PhC(NSiMe3)(2)Mg{mu-NC(CH2SiMe3)Ph}](2) (1). It appears that at least six independent reactions must have occurred in this one-pot reaction to arrive at this mixed benzamidinate ketimido product. Two benzonitrile solvated derivatives of Mg(CH2SiMe3)(2) (5a and 5b) have been synthesized, with 5a crystallographically characterized as a centrosymmetric (MgC)(2) cyclodimer. When, the components of 5a are allowed to react for longer, partial addition of the Mg-alkyl unit across the C N triple bond occurs to yield the trimeric species (Me3SiCH2)(2)Mg-3[mu-N=C(CH2SiMe3)Ph](4)center dot 2N CPh (6), with bridging ketimido groups and terminal alkyl groups. Finally, using the same starting materials as that which produced 1, but altering their order of addition, a magnesium bis-alkyl unit is inserted into the Na-N bonds of a benzamidinate species to yield a new sodium magnesiate complex, PhC(NSiMe3)(2)Mg(mu-CH2SiMe3)(2)Na center dot 2TMEDA (7). The formation of 7 represents a novel (insertion) route to mixed-metal species of this kind and is the first Such example to contain a bidentate terminal anion attached to the divalent metal center. All new species are characterized by H-1 and C-13 NMR spectroscopy and where appropriate by IR spectroscopy. The solid-state structures of complexes 1, 5a, and 7 have also been determined and are disclosed within
Reactions of (-)-sparteine with alkali metal HMDS complexes : conventional meets the unconventional
Conventional (-)-sparteine adducts of lithium and sodium 1,1,1,3,3,3-hexamethyldisilazide (HMDS) were prepared and characterised, along with an unexpected and unconventional hydroxyl-incorporated sodium sodiate, [(-)-sparteine·Na(-HMDS)Na·(-)-sparteine]+[Na4(-HMDS)4(OH)]--the complex anion of which is the first inverse crown ether anion
Liquid Metal Sources in Ion Microscopy and Secondary Ion Mass Spectrometry
This paper reports on state-of-the-art developments in liquid metal sources and some of the finer points of their operating characteristics that are especially relevant to the satisfactory functioning of analytical ion scanning microscopes equipped with secondary ion mass spectrometers. Such effects include unwanted emissions from the source and their exclusion by means of filters and mass separators in the ion-optical column. The design of the ion-optical column is also discussed and some applications of this rapidly advancing form of analytical microscopy are described
Lithium and aluminium carbamato derivatives of the utility amide 2, 2, 6, 6- tetramethylpiperidide
Insertion of CO2 into the metal-N bond of a series of synthetically-important alkali-metal TMP (2,2,6,6-tetramethylpiperidide) complexes has been studied. Determined by X-ray crystallography, the molecular structure of the TMEDA-solvated Li derivative shows a central 8-membered (LiOCO)2 ring lying in a chair conformation with distorted tetrahedral lithium centres. While trying to obtain crystals of a THF solvated derivative, a mixed carbonato/carbamato dodecanuclear lithium cluster was formed containing two central (CO3)2- fragments and eight O2CTMP ligands with four distinct bonding modes. A bisalkylaluminium carbamato complex has also been prepared via two different methods (CO2 insertion into a pre-formed Al-N bond and ligand transfer from the corresponding lithium reagent) which adopts a dimeric structure in the solid state
Properties of the Scalar Universal Equations
The variational properties of the scalar so--called ``Universal'' equations
are reviewed and generalised. In particular, we note that contrary to earlier
claims, each member of the Euler hierarchy may have an explicit field
dependence. The Euler hierarchy itself is given a new interpretation in terms
of the formal complex of variational calculus, and is shown to be related to
the algebra of distinguished symmetries of the first source form.Comment: 15 pages, LaTeX articl
Exploring career decision-making styles across three European countries
Career decisions are amongst the most important we make. Unsurprisingly, much published
research exists on this particular aspect of career behaviour. However, the overwhelming
majority of studies have been carried out on young people making initial career decisions.
This paper extends our understanding by examining how mid-career adults in three European
countries (Denmark, France and Italy) actually make career decisions. Characteristic patterns
of behavior recur when individuals approach points of transition or of crisis; each of these
transitioning styles is illustrated by an iconic case. Emergent findings support the growing
body of evidence that challenges the dominant policy and practice orthodoxy, which places
rationality at the center of the process, by recognising the importance of emotion and context
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