2-(2-Chloro­phen­yl)-3-(3,4-dimeth­oxy­phen­yl)quinoxaline

The title compound, C22H17ClN2O2, was synthesized by the condensation reaction between 1,2-phenyl­enediamine and 2-chloro-3′,4′-dimeth­oxy­benzil in boiling acetic acid. The chloro­phenyl and dimeth­oxy­phenyl rings make dihedral angles of 78.45 (5) and 35.60 (4)°, respectively, with the quinoxaline unit

Structural and electronic effects of mono- and bidentate perfluorinated alkoxide ligands in late first-row transition metal complexes

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Seven homoleptic first-row transition metal complexes were prepared with the perfluoro-t-butoxide ligand with three- and four-coordinate geometry. The compounds were prepared via metathesis reactions with the form [M(OC4F9)3]-, M = Mn (1), Fe (2), Co (5), and Zn (7); [M(OC4F9)4]n-, M = Fe (4), Co (6); and the THF adducts [M(THF)(OC4F9)3]- M = Co (5-TBF), and Zn (7-THF). The complexes were synthesized and structurally characterized. Spectroscopic characterization with UV-vis, NMR, and IR will be discussed. Cyclic voltammetry studies of 5 and 6 in conjunction with UV-vis data show the presence of an equilibrium between the three- and four-coordinate complexes with ligand association and dissociation. Using the bidentate perfluorinated pinacolate ligand, ddfp, three complexes were prepared as [M(ddfp)2]2-, in which M =Fe (8), Co (9), and Zn (10). Complexes 8 and 9 have square-planar geometry and are high-spin. The magnetism was studied both in solution and the solid state. The combination of geometry and spin-state is rare for {M04} complexes and 9 is the first example of {C0O4} with this combination, and 8 is the second example of this combination in an {FeO4} system. A five-coordinate Co complex was also structurally characterized (9-OH2). A family of heteroleptic complexes of the form [Fe(X)(OC4F9)3]- in which X = Cl (11), Br (12), or pyridine (13), and [M(py)(ddfp)2]2- for M= Co (14), and Fe (15), were prepared and some were structurally characterized. Analytical data suggests the formation of an iron-amide complex, [Fe(HN(C6H5)(ddfp)2]3-, (16), capable of further reactivity. The synthesis, characterization, and preliminary reactivity studies will be discussed. Two iron aryloxide complexes were synthesized with the pentafluorophenolate ligand, [Fe(OArF)4]2-, (17) and [(OArF)3Fe(μ2-OArF)2Fe(OArF)3]2-, (18). The FeIII complex was formed as a result of presumed ligand oxidation and dissociation, highlighting the vulnerability of aryloxide ligands. A series of isotopically labeled compounds containing a short, strong hydrogen bond were prepared and characterized for neutron diffraction experiments. The compounds, [Cp2Co][D(OAr5)], (19) and d10-[Cp2Co][H(OAr')], (20), were prepared with the partially fluorinated OAr' ligand, bis-(3,5-trifluoromethyl)phenoxide. The synthesis and characterization of these compounds will be discussed

AtLAST Science Overview Report

International audienceSubmillimeter and millimeter wavelengths provide a unique view of the Universe, from the gas and dust that fills and surrounds galaxies to the chromosphere of our own Sun. Current single-dish facilities have presented a tantalising view of the brightest (sub-)mm sources, and interferometers have provided the exquisite resolution necessary to analyse the details in small fields, but there are still many open questions that cannot be answered with current facilities. In this report we summarise the science that is guiding the design of the Atacama Large Aperture Submillimeter Telescope (AtLAST). We demonstrate how tranformational advances in topics including star formation in high redshift galaxies, the diffuse circumgalactic medium, Galactic ecology, cometary compositions and solar flares motivate the need for a 50m, single-dish telescope with a 1-2 degree field of view and a new generation of highly multiplexed continuum and spectral cameras. AtLAST will have the resolution to drastically lower the confusion limit compared to current single-dish facilities, whilst also being able to rapidly map large areas of the sky and detect extended, diffuse structures. Its high sensitivity and large field of view will open up the field of submillimeter transient science by increasing the probability of serendipitous detections. Finally, the science cases listed here motivate the need for a highly flexible operations model capable of short observations of individual targets, large surveys, monitoring programmes, target of opportunity observations and coordinated observations with other observatories. AtLAST aims to be a sustainable, upgradeable, multipurpose facility that will deliver orders of magnitude increases in sensitivity and mapping speeds over current and planned submillimeter observatories