Monodentate Alkoxy/Aryloxy Anchored Yttrium Dihydrides; Anticipated Outcomes and Surprises.

The synthesis, characterization, and solid-state structure of bulky alkoxy- and aryloxy-supported yttrium polynuclear hydrides are reported. Hydrogenolysis of the supertrityl alkoxy anchored yttrium dialkyl, Y(OTr*)(CHSiMe)(THF) () (Tr* = tris(3,5-di--butylphenyl)methyl), resulted in the clean conversion to the tetranuclear dihydride, [Y(OTr*)H(THF)] (). X-ray analysis revealed a highly symmetrical structure (̅ site symmetry) with the four Y atoms located on the corners of a compressed tetrahedron, each bonded to an OTr* and tetrahydrofuran (THF) ligand and the cluster held together by four face-capping, μ-H, and four edge-bridging, μ-H, hydrides.

Development of an alarm symptom-based risk prediction score for localized oesophagogastric adenocarcinoma (VIOLA score).

Background: Gastroesophageal adenocarcinoma is a major contributor to global disease burden with poor prognosis even in resectable, regionally limited stages. Feasible prognostic tools are crucial to improve patient management, yet scarce.

Patients And Methods: Disease-related symptoms, patient, tumour, treatment as well as laboratory parameters at initial diagnosis and overall survival (OS) of patients with stage II and III gastroesophageal adenocarcinoma, who were treated between 1990 and 2020 at the Medical University of Vienna, were evaluated in a cross-validation model to develop a feasible risk prediction score.

Synthesis and Structure of Alkaline Earth Bis{hydrido-tris(3,5-diisopropyl-pyrazol-1-yl)borate} Complexes: Ae(Tp) (Ae = Mg, Ca, Sr, Ba).

The synthesis and structural characterization of Ae(Tp) (Ae = Mg, Ca, Sr, Ba; Tp = hydrido-tris(3,5-diisopropyl-pyrazol-1-yl)borate) are reported. In the crystalline state, the alkaline earth metal centers are six-coordinate, even the small Mg ion, with two κ-,',''-Tp ligands, disposed in a bent arrangement (B···Ae···B < 180°). However, contrary to the analogous Ln(Tp) (Ln = Sm, Eu, Tm, Yb) compounds, which all exhibit a bent-metallocene structure close to symmetry, the Ae(Tp) compounds exhibit a greater structural variation.

Crystal structure of tri-benzyl-bis-(tetra-hydro-furan-κ)lutetium(III).

In the title compound, [Lu(CH)(CHO)] (), the Lu ion is coordinated by three benzyl and two tetra-hydro-furan ligands. Two of the benzyl groups are bonded in a classical η-fashion through the methyl-ene the -carbon atom of the benzyl ligand in addition to bonding through the methyl-ene C atom, resulting in a modified trigonal-bipyramidal coordination geometry about the Lu center.

Formation and structural characterization of a europium(II) mono(scorpionate) complex and a sterically crowded pyraza-bole.

The reaction of EuI(THF) with potassium hydro-tris-(3,5-diiso-propyl-pyrazol-yl)borate (K[HB(3,5- pz)] (= KTp , pz = pyrazol-yl) in a molar ratio of 1:1.5 resulted in extensive ligand fragmentation and formation of the europium(II) mono(scorpionate) complex bis-(3,5-diisopropyl-1-pyrazole)[hydro-tris-(3,5-diiso-propyl-pyrazol-yl)borato]iodido-europium(II), [Eu(CHBN)I(CHN)] or (Tp )(3,5- pzH)EuI, , in high yield (78%). As a typical by-product, small amounts of the sterically crowded pyraza-bole derivative -4,8-bis-(3,5-diiso-propyl-pyrazol-1-yl)-1,3,5,7-tetra-iso-propyl-pyraza-bole, CHBH or -{(3,5- pz)HB(μ-3,5- pz)}, , were formed.

Stabilization of molecular lanthanide polysulfides by bulky scorpionate ligands.

Well-defined lanthanide polysulfide complexes containing S4(2-) and S5(2-) ligands, the samarium(iii) pentasulfide complex Sm(Tp(iPr2))(κ(1)-3,5-(i)Pr2Hpz)(S5) and the tetrasulfide-bridged binuclear ytterbium(iii) complex (μ-S4)[Yb(Tp(iPr2))(κ(1)-3,5-(i)Pr2Hpz)(κ(2)-3,5-(i)Pr2pz)]2 (Tp(iPr2) = hydro-tris(3,5-diisopropylpyrazolyl)borate), have been synthesized and structurally characterized by single-crystal X-ray diffraction.

To bend or not to bend: experimental and computational studies of structural preference in Ln(Tp(iPr)2)2 (Ln = Sm, Tm).

The synthesis and characterization of Ln(Tp(iPr2))2 (Ln = Sm, 3Sm; Tm, 3Tm) are reported. While the simple (1)H NMR spectra of the compounds indicate a symmetrical solution structure, with equivalent pyrazolyl groups, the solid-state structure revealed an unexpected, "bent sandwich-like" geometry. By contrast, the structure of the less sterically congested Tm(Tp(Me2,4Et))2 (4) adopts the expected symmetrical structure with a linear B-Tm-B arrangement.

Protected areas and freshwater conservation: a survey of protected area managers in the Tennessee and Cumberland River Basins, USA.

As the scientific community has highlighted the plight of freshwater species, there have been increasing calls for protected area (PA) designation and management specific to the conservation of aquatic species and ecosystems. In this study we examined PA management in one relatively well-resourced (high levels of financial and technical resources) part of the world: the Tennessee and Cumberland River Basins, USA. We asked managers their perceptions about the current status of freshwater ecosystems within PAs, the sources of stress that are degrading freshwater ecosystem integrity, the degree to which PAs address these stressors, and the availability of technical, human, and financial resources for management activities that benefit freshwater ecosystems and the species they support.

Synthesis and structure of divalent thulium borohydrides, and their application in ε-caprolactone polymerisation.

The new divalent thulium compound [Tm(BH(4))(2)(DME)(2)] could be prepared by reduction of [Tm(BH(4))(3)(THF)(3)] or from TmI(2) and KBH(4). It was used as a precursor to the divalent [(Tp(tBu,Me))Tm(BH(4))(THF)] by reaction with potassium tris(2-tBu-4-Me)pyrazolylborate (KTp(tBu,Me)). Both Tm(II) compounds were found active as ε-caprolactone polymerisation catalysts.

Stable heteroleptic complexes of divalent lanthanides with bulky pyrazolylborate ligands--iodides, hydrocarbyls and triethylborohydrides.

The reaction of YbI(2) with KTp(Me2) gives (Tp(Me2))YbI(THF)(2) (1-Yb) as a thermally unstable product. Use of the more hindered KTp(tBu,Me) gave (Tp(tBu,Me))LnI(THF)(n) (Ln = Sm, n = 2, 2-Sm; Ln = Yb, n = 1, 2-Yb). The crystal structures of both these compounds are reported.

Synthesis and reaction of [(Tp(iPr2))LnH2]3 (Ln = Y, Lu) with CO: trinuclear cluster-bound propenolate en route to selective formation of propene.

The use of the Tp(iPr(2)) ligand led to the straightforward and high-yield synthesis of rare examples of trinuclear monoligand lanthanide dihydrides, [(Tp(iPr(2)))LnH(2)](3) (Ln = Y, Lu). The Y complex was found to mediate the hydrogenation and coupling of carbon monoxide with exclusive formation of propene via the intermediacy of a cluster-bound propenolate ligand.

Bis[tris(3-tert-butyl-5-methyl-pyrazol-1-yl)hydridoborato]ytterbium(II) toluene solvate.

In the title compound, [Yb(C(24)H(40)BN(6))(2)]·C(7)H(8), the Yb atom is coordinated by two tris(3-tert-butyl-5-methyl-pyrazol-1-yl)hydridoborate [Tp(tBu,Me)] ligands. One ligand binds in the κ(3) mode, throuh three N atoms of the pyrazolyl rings, the other ligand coordinates through two N atoms of the pyrazolyl rings and the H atom attached to the central B via an agostic-type inter-action through the B-H group of the second Tp(tBu,Me) ligand, giving an overall distorted octa-hedral geometry. One of the tert-butyl groups is disordered over two sites, with occupancies of 0.

Ln(III) methyl and methylidene complexes stabilized by a bulky hydrotris(pyrazolyl)borate ligand.

The reaction of Ln(AlMe(4))(3) with bulky hydrotris(pyrazolyl)borate (Tp(t)(Bu,Me))H proceeds via a sequence of methane elimination and C-H bond activation, affording unprecedented rare-earth metal ligand moieties including Ln(Me)[(micro-Me)AlMe(3)] and X-ray structurally characterized "Tebbe-like" Ln[(micro-CH(2))(2)AlMe(2)].

Trapping of anionic organic radicals by (TpMe2)2Ln (Ln = Sm, Eu).

Stoichiometric reaction of [ Sm(Tp(Me2))2 ], 1, with a variety of reducible ketone- and quinone-type substrates gave thermally stable, isolable radical anions/ketyls in moderate to good yields. Thus reaction with benzophenone gave [Sm(Tp(Me2))2(OCPh2)], 2, with fluorenone [Sm(Tp(Me2))2(eta1-OC13H8)], 3, and di-tert-butylparaquinone [Sm(Tp(Me2))2(eta1-OC6H2(tBu)2O)], 4, each of which was structurally characterized. In the case of the less-hindered benzoquinone, an unimetallic semiquinone [Sm(Tp(Me2))2(OC6H4O)], 5, could be isolated, although it was unstable with respect to formation of the dimetallic complex [Sm(Tp(Me2))2]2(mu-OC6H4O), 6.

Uranium (III) scorpionates: synthesis and structure of [(TpMe2)2U[N(C6H5)2]] and [(TpMe2)2U[N(SiMe3)2]].

Reaction of [(Tp(Me)2)(2)UI] with KNR(2) (R = C(6)H(5), SiMe(3)) in tetrahydrofuran (THF) afforded the monomeric trivalent actinide amide complexes [(Tp(Me)2)(2)U[N(C(6)H(5))(2)]], 1, and [(Tp(Me)2)(2)U[N(SiMe(3))(2)]], 2. The complexes have been fully characterized by spectroscopic methods and their structures were confirmed by X-ray crystallographic studies. In the solid state 1 and 2 exhibit distorted pentagonal bipyramidal geometries.

Facile pyrazolylborate ligand degradation at lanthanide centers: X-ray crystal structures of pyrazolylborinate-bridged bimetallics.

Adventitious hydrolysis of a number of different complexes with the molecular formula Ln(Tp(Me2))(2)X [Tp(Me2) = (HB(dmpz)(3)), where X is a basic anionic ligand] in various solvents, yielded crystals of highly insoluble dimers of the general formula [Ln(Tp(Me2))(mu-BOp(Me2))](2) (1) [Ln = La, Ce, Sm; BOp(Me2) = (HBO(dmpz)(2))(2)(-); dmpzH = 3,5-dimethylpyrazole]. The results of several single-crystal X-ray determinations are reported. One metal nitrogen distance, that lying across from the two negatively charged bridging oxygen atoms, is 0.

Synthesis and structural comparison of a series of divalent Ln(Tp(R,R)')2 (Ln = Sm, Eu, Yb) and trivalent Sm(Tp(Me2))2X (X = F, Cl, I, BPh4) complexes.

Reaction of LnI2 (Ln = Sm, Yb) with two equivalents of NaTp(Me2) or reduction of Eu(Tp(Me2))2OTf gives good yields of the highly insoluble homoleptic Ln(II) complexes, Ln(Tp(Me2))2 (Ln = Sm (1a), Yb (2a), Eu (3a)). Use of the additionally 4-ethyl substituted Tp(Me2,4Et) ligand produces the analogous, but soluble Ln(Tp(Me2,4Et))2 (1-3b) complexes. Soluble compounds are also obtained with the Tp(Ph) and Tp(Tn) ligands (Tn = thienyl), Ln(Tp(Ph))2 (Ln = Sm, 1c; Yb, 2c) and Ln(Tp(Tn))2 (Ln = Sm, 1d; Yb, 2d).

Stabilization of a Discrete Lanthanide(II) Hydrido Complex by a Bulky Hydrotris(pyrazolyl)borate Ligand.

Divalent and solvent-free: the ytterbium hydrido complex 1 was obtained by the hydrogenolysis of [(Tp(tBu,Me))Yb(CH(2)SiMe(3))(thf)]. The steric demand of the bulky hydrotris(3-tert-butyl-5-methylpyrazolyl)borate ligand, Tp(tBu,Me), is sufficient to stabilize the dimer, yet facile room-temperature reactions with amines, alkynes, diynes, and CO indicate a rich chemistry of 1.