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Iridium bis(iminoxolene) complexes with 2,6-dibromophenyl substituents can be prepared in four different oxidation states, including a reduced complex with a sodium–iridium bond. 

The bis(iminoxolene) complex (Diso)2IrCl (Diso = N-(2,6-diisopropylphenyl)-4,6-di-tert-butyl-2-imino-o-benzoquinone) is reduced by two equivalents of sodium naphthalenide to give square planar, diamagnetic Na[(Diso)2Ir]. The anionic iridium center acts as a nucleophile to primary and secondary alkyl and allyl halides to give square pyramidal iridium alkyls. Benzoyl chloride reacts to give an iridium benzoyl complex. Organoiridium complexes are also formed by reaction of (Diso)2IrCl with Grignard reagents, and treatment with acetone in the presence of base gives the 1 carbon-bonded enolate complex (Diso)2IrCH2COCH3. The solid-state structures of the primary alkyls show significant inclinations of the iridium-carbon bond away from the twofold axis of the square pyramid, apparently for steric reasons. The relative reactivity of substrates and exclusive formation of (Diso)2Ir(5-hexenyl) from 1-bromo-5-hexene indicates that primary alkyl halides react by an SN2 mechanism. Structural data suggest that the oxidative addition is about 70% metal centered, consistent with nucleophilic behavior that is analogous to that of other square planar group 9 anions. 

Abstract We present the Local GroupL-Band Survey, a Karl G. Jansky Very Large Array (VLA) survey producing the highest-quality 21 cm and 1–2 GHz radio continuum images to date, for the six VLA-accessible, star-forming, Local Group galaxies. Leveraging the VLA’s spectral multiplexing power, we simultaneously survey the 21 cm line at high 0.4 km s⁻¹velocity resolution, the 1–2 GHz polarized continuum, and four OH lines. For the massive spiral M31, the dwarf spiral M33, and the dwarf irregular galaxies NGC 6822, IC 10, IC 1613, and the Wolf–Lundmark–Melotte Galaxy, we use all four VLA configurations and the Green Bank Telescope to reach angular resolutions of <5″ (10–20 pc) for the 21 cm line with <10²⁰cm⁻²column density sensitivity, and even sharper views (<2″; 5–10 pc) of the continuum. Targeting these nearby galaxies (D ≲ 1 Mpc) reveals a sharp, resolved view of the atomic gas, including 21 cm absorption, and continuum emission from supernova remnants and Hiiregions. These data sets can be used to test theories of the abundance and formation of cold clouds, the driving and dissipation of interstellar turbulence, and the impact of feedback from massive stars and supernovae. Here, we describe the survey design and execution, scientific motivation, data processing, and quality assurance. We provide a first look at and publicly release the wide-field 21 cm Hidata products for M31, M33, and four dwarf irregular targets in the survey, which represent some of the highest-physical-resolution 21 cm observations of any external galaxies beyond the LMC and SMC. 

Reaction of the 9,9-dimethylxanthene-bis(imine)-bis(catechol) ligand XbicH 4 with half an equivalent of Zr(acac) 4 affords the neutral tetracatecholate complex (XbicH 2 ) 2 Zr, containing four iminium ions hydrogen bonded to the catecholates. The heteroleptic bis(catecholate)-tetraphenylporphyrin complex (TPP)Zr(XbicH 2 ) is formed from reaction of (TPP)Zr(OAc) 2 with XbicH 4 in the presence of base. Both compounds adopt an eight-coordinate square antiprismatic geometry around the zirconium center. NMR spectra of (TPP)Zr(XbicH 2 ) show that it is fluxional at room temperature, with homoleptic (XbicH 2 ) 2 Zr showing fluxionality at higher temperatures. Calculations and kinetic isotope effect measurements suggest that the motions involve dissociation of a single catecholate oxygen and subsequent twisting of the seven-coordinate species. The compounds show reversible one-electron oxidations of each of the bound catecholates to bound semiquinones. 

Schiff base condensation of 4,5-diamino-9,9-dimethylxanthene with 4,6-di- tert -butylcatechol-3-carboxaldehyde affords the bis(catecholimine) ligand XbicH 4 , which can bind metals in both a square bis(catecholate) upper pocket and a pentagonal N 2 O 3 lower pocket. Metalation with PhSiCl 3 results in [(XbicH 2 )SiPh][HCl 2 ], where the silicon adopts a five-coordinate, square pyramidal geometry in the upper pocket and the lower pocket binds to two protons on the imine nitrogens. Deprotonation of the imines with LiO t Bu, NaN[SiMe 3 ] 2 , or AgOAc results in binding of the univalent metal ion in the lower pocket, where it adopts an unusual pentagonal monopyramidal geometry in the solid state. The complexes show irreversible electrochemistry, with oxidations taking place at relatively high potentials.