Infrared Spectroscopic and Theoretical Investigations of Group 13 Oxyfluorides OMF2 and OMF (M = B, Al, Ga, In)

Group 13 oxyfluorides OMF2 were produced by the reactions of laser-ablated group 13 atoms M (M = B, Al, Ga and In) with OF2 and isolated in excess neon or argon matrices at 5 K. These molecules were characterized by matrix-isolation infrared spectroscopy and isotopic substitution experiments in conjunction with quantum-chemical calculations. The calculations indicate that the OMF2 molecules have a 2B2 ground state with C2v symmetry. The computed molecular orbitals and spin densities show that the unpaired electron is mainly located at the terminal oxygen atom. Oxo monofluorides OMF were only observed in solid argon matrices and exhibit a linear structure in the singlet ground state. The M−O bonding in the OMF molecules can be rationalized as highly polar multiple bonds based on the calculated bond lengths and natural resonance theory (NRT) analyses. In particular, the molecular orbitals of OBF exhibit the character of a triple bond B−O resulting from two degenerate electron-sharing π bonds and a O → B dative σ bond formed by the oxygen 2p lone pair which donates electron density to the boron empty 2p orbital

Nitrogen Trifluoride Complexes of Group 10 Transition Metals M(NF3) (M = Pd, Pt)

The group 10 transition metal atoms Pd and Pt react with nitrogen trifluoride (NF3) forming N-coordination M(NF3) complexes in solid neon and argon matrices. The M(NF3) complexes isomerize to more stable fluoronitrenoid FNMF2 isomers via fluorine migration upon blue LED (λ = 470 nm) light irradiation. These products are characterized on the basis of infrared absorption spectroscopy with isotopic substitutions and theoretical frequency calculations. The analysis of the electronic structure of nitrogen trifluoride complexes indicates that the bonding between metal and nitrogen trifluoride can be described as σ donation from the HOMO of nitrogen trifluoride to the empty metal dz2 orbital and π back-donation from the metal dxz/yz orbitals to the LUMO of nitrogen trifluoride, the latter of which stabilized the metal ligand bond and destabilized the ligand N–F bond. In FNMF2, the FN ligand doubly bonded to the metal and bear imido character

Methanesulfonyl Azide: Molecular Structure and Photolysis in Solid Noble Gas Matrices

The parent sulfonyl azide CH₃SO₂N₃ has been characterized in a neat form by IR (gas, matrix-isolation) and Raman (solid) spectroscopy, and its structure has been established by X-ray crystallography. In both gas phase and solid state, the azide exhibits single conformation with the azido ligand being synperiplanar to one of the two SO groups. In the crystal molecules of CH₃SO₂N₃ are interconnected through three-dimensional O···H–C–H···O hydrogen bonds. Upon an ArF laser (193 nm) photolysis, the azide in solid noble gas matrices splits off N₂ and yields the sulfonyl nitrene CH₃SO₂N in the triplet ground state. Subsequent photolysis with UV light (266 nm) causes the transformation from the nitrene to the pseudo-Curtius rearrangement product CH₃NSO₂. The identification of the photolysis intermediates by matrix-isolation IR spectroscopy is supported by quantum chemical calculations with DFT methods

Facile synthesis of metal-polyphenol-formaldehyde coordination polymer colloidal nanoparticles with sub-50 nm for T1-weighted magnetic resonance imaging

Plant polyphenol-based coordination polymers (CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applications, but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. Herein, a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species (e.g., Gd, Cu, Ni, Zn, Fe) and ultra-small diameter (8.6–37.8 nm) using nontoxic plant polyphenol (e.g., tannic acid, gallic acid) as a polymerizable ligand. Polyphenol molecules react with formaldehyde firstly, which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal nanoparticles. These ultrafine nanoparticles with stably chelated metal ions are highly water dispersible and thus advantageous for bioimaging. As an example, ultra-small Gd contained CPs exhibit higher longitudinal relaxivity (r1 = 25.5 L mmol−1 s−1) value with low r2/r1 (1.19) than clinically used Magnevist (Gd-DTPA, r1 = 3.7 L mmol−1 s−1). Due to the enhanced permeability and retention effect, they can be further used as a positive contrast agent for T1-weighted MR imaging of tumour.Scopu

Simplest <i>N</i>‑Sulfonylamine HNSO₂

The simplest <i>N</i>-sulfonylamine HNSO₂ has been generated in the gas phase through flash vacuum pyrolysis of methoxysulfonyl azide CH₃OS­(O)₂N₃. Its identification was accomplished by combining matrix-isolation IR spectroscopy and quantum chemical calculations. Both experimental and theoretical evidence suggest a stepwise decomposition of the azide via the methoxysulfonyl nitrene CH₃OS­(O)₂N, observed in the 193 nm laser photolysis of the azide, with concerted fragmentation into CH₂O and HNSO₂. Upon the 193 nm laser irradiation, HNSO₂ isomerizes into the novel <i>N</i>-hydroxysulfinylamine HONSO