Search results for "Oct"
showing 10 items of 3052 documents
Study of the themes and contents of the doctoral theses carried out in Spain on Sports Biomechanics
2022
El objeto del estudio es conocer y valorar la evolución de las temáticas y contenidos de las tesis doctorales que se han leído en España sobre Biomecánica Deportiva durante el periodo comprendido entre los años 1980 y 2019. La muestra está compuesta de 233 tesis después de un proceso de selección con el uso de criterios de inclusión/exclusión y términos de búsqueda específicos. Los resultados demuestran que existe un crecimiento progresivo en la producción de tesis doctorales a lo largo del tiempo con incrementos progresivos, especialmente en el tercer y cuarto periodo. Los campos temáticos con mayor número de tesis leídas son los de Biomecánica de Apoyo y de Biomecánica Aplicada. El campo …
The Psychological Science Accelerator’s COVID-19 rapid-response dataset
2023
Funder: Amazon Web Services (AWS) Imagine Grant
A linear open-chain piperazine-pyridine ligand and its meso-helical Co complex
1998
Abstract An oligomeric ligand (HPPy) 2 P, N , N ′-bis[2-(6-( N -( N ′-(2-hydroxyethyl)piperazinyl)methyl)]piperazine, was designed to resemble structurally open-chain aza-crowns. Owing to the all- trans configuration of piperazine and pyridine free electron pairs, it should adopt a near linear overall structure in solvent. Theoretical calculations at ab initio level confirm the overall linear structure of free ligand. The crystal structure of the complex [(HPPy) 2 P][Co(NO 3 ) 2 ] 2 shows a contraction from ∼3 to 2 nm structure. Each coordination site creates either a Δ or Δ configuration around the metal ion, thus causing a ligand with an even number of coordination centres to be meso -hel…
Synthesis and spectroscopic studies (Mo¨ssbauer, IR and NMR) of [R2SnCl2bipym] (R = butyl or phenyl) and the crystal and molecular structure of [Ph2S…
1994
Abstract The complexes [R 2 SnCl 2 bipym] (R = phenyl or butyl, bipym = 2,2′,6,6′-bipyrimidine) were synthesized and studied in solution by 1 H- and 13 C-NMR spectroscopy and in the solid state by IR and Mo¨ssbauer spectroscopy. The latter was also performed in frozen ethanolic solution. The structure of the phenyl complex was determined by single crystal diffraction methods. The value obtained for the angle C-SN-C in the phenyl compound is 169.3(2)° (X-ray) and 151° (Mo¨ssbauer), but the assignment of an octahedral configuration by Mo¨ssbauer spectroscopy is consistent with the structure determined by diffraction. The butyl complex is also octahedral and the two techniques show better agre…
Synthesis, crystal structure and magnetic properties of [Cu2(bpym)(N3)4] (bpym=2,2′-bipyrimidine)
1993
Abstract The compound of formula [Cu 2 (bpym)(N 3 ) 4 ] (bpym=2,2′-bipyrimidine) has been synthesized and its crystal structure determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P 2 1 / n with cell constants: a =10.071(2), b =6.376(1), c =11.617(2) A and β=95.93(1)°; V =742.0(2) A 3 , D (calc., Z =2)=2.029 g cm −3 , M r =453.4, F (000)=448, λ (Mo Kα)=0.71073 A, μ (Mo Kα)=29.1 cm −1 and T =298 K. A total of 2027 reflections was collected over the range 3⩽2θ⩽55°; of these, 1723 were unique and 1427 were considered as observed ( I >3σ( I )) and used in the structural analysis. The final R and R w residuals were 0.0275 and 0.0328, respectively. The structure…
Synthesis and structural, spectroscopic and magnetic characterization of iron(II) and iron(III) complexes of N-2-pyridinylcarbonyl-2-pyridinecarboxim…
1993
Abstract One iron(II) complex of N -2-pyridinylcarbonyl-2-pyridinecarboximidate monoanion (bpca), [Fe(bpca) 2 ]·H 2 O ( 1 ), and three iron(III) complexes, [Fe(bpca)Cl 2 (H 2 O)]·(CH 3 ) 2 CO ( 2 ), [Fe(bpca) 2 ](NO 3 )·1.67H 2 O ( 3 ), [Fe(bpca) 2 ](ClO 4 ) ( 4 ), have been prepared and characterized by means of IR, UV-Vis and EPR spectroscopy and magnetic susceptibility measurements, where appropriate. The crystal structures of 1 – 3 have been determined from single crystal X-ray data, showing that the metallic ions are surrounded in all cases by distorted octahedral coordination spheres. From magnetic measurements it is evident that compounds 1 and 3 are practically in the low-spin state…
Selective Crystallization of Dimeric vs. Monomeric Dimethyltin‐Containing Tungstoarsenates(III) and ‐antimonates(III) with the Guanidinium Cation
2009
The use of guanidinium cations [C(NH 2 ) 3 ] + as crystallizing agents allowed us to selectively isolate the dimeric [{(CH 3 ) 2 -Sn(H20)} 4 {(CH 3 ) 2 Sn}(B-β-XW 9 O 33 ) 2 ] 8- (1, X = As III ; 2, X = Sb III ) polyanions from the reaction of (CH 3 ) 2 SnCl 2 with Na 9 [B-a-XW 9 O 33 ) (3:1 ratio) in water at pH 3. This reaction is known to give the monomeric [{(CH 3 ) 2 Sn(H 2 O) 2 } 3 (B-β-XW 9 O 33 )] 3- polyanions as the major species. Polyanions 1 and 2 are composed of one octahedral trans-(CH 3 ) 2 SnO 4 moiety that bridges two trilacunary [B-β-XW 9 O 33 ] 9- Keggin subunits further decorated by two structurally nonequivalent {(CH 3 ) 2 Sn} 2+ functionalities each: one distorted octa…
Synthesis, structural characterization and electrochemical activity of oxidovanadium(IV/V) complexes of a diprotic ONS chelating ligand
2010
Abstract The present work reports the chemistry of a few oxidovanadium(IV) and (V) complexes of the ONS chelating ligand S-benzyl-β-N-(2-hydroxyphenylethylidine) dithiocarbazate (H2L). Major objective of this work is to arrive at some general conclusions about the influence of binding environment generated by the replacement of an O-donor center by a S-donor point in a ligand (of a similar arrangement of the other O- and N-donor points) on the redox behavior and on the structural features of comparable [VO(OEt)(ONS)] and [VO(OEt)(ONO)] complexes. Synthesis, characterization by various physicochemical techniques (UV–Vis, IR, EPR and elemental analysis), exploration of electrochemical activit…
Über antimon-haltige heterocyclen
1980
Abstract p -Nitrophenyl- and p -tolyl-oxadithia- and trithiastibocanes have been synthesized from the respective aryldichlorostibane and dithiole. The compounds have been characterised by means of 13 C NMR and vibrational spectra (ν(SBS 2 ) 350–320 cm −1 ). The crystal structure of p -nitrophenyltrithiastibocane has been determined ( R = 0.042). The eight-membered ring exhibits a boat-chair conformation. Single-bond distances of SbC and SbS (219, 244 and 245 pm), a 1,5-transannular Sb⋯S interaction (319 pm), and Sb⋯S and Sb⋯O (339 and 353 pm) intermolecular contacts, result in a six-coordinated Sb III (ψ-monocapped octahedral) species. The two additional Sb⋯S distances are in accordance w…
Crystal structure and physical properties of the new linear chain compound [Cu(1,2-bis(tetrazol-1-yl)ethane)3](ClO4)2
2001
The synthesis and crystal structure of a novel one-dimensional Cu(II) compound [Cu(1,2-bis(tetrazol-1-yl)ethane)3](ClO4)2 are described. The single-crystal X-ray structure determination was carried out at 298 K. The molecular structure consists of a linear chain in which the Cu(II) ions are linked by three N4,N4' coordinating bis(tetrazole) ligands in syn conformation. The Cu(II) ions are in a Jahn-Teller distorted octahedral environment (Cu(1)-N(11)=2.034(2) A, Cu(1)-N(21)=2.041(2) A and Cu(1)-N(31)=2.391(2) A). The Cu⋯Cu separations are 7.420(3) A.