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The d- and l-enantiomers of the ternary complex [Cu(phen)(ala)(H2O)]NO3 [phen = 1,10-phenanthroline; ala = alanine; l-enantiomer (1a); d-enantiomer (1b)] both undergo an aldol-type condensation with formaldehyde under mild acidic conditions to yield racemic rac-[Cu(phen)(4MeOCA)(H2O)(NO3)] (2) (4MeOCA = 4-methyl-oxazolidine-4-carboxylate). The precursors and the products were characterized by circular dichroism, FTIR, UV–Vis, fluorescence spectroscopy, molar conductivity and electrospray ionization mass spectrometry. The racemic nature of the product was established by X-ray crystallography. In the crystal structure, the copper atom has a tetragonally elongated octahedral geometry in which the water and an oxygen atom of a nitrate group are mutually trans. A possible mechanism for the racemization of the ligand is proposed. © 2016, Springer International Publishing Switzerland.

World University root node

Transition Metal Chemistry

Rac-aqua(4-methyl-oxazolidine-4-carboxylato)(nitrato)(1,10-phenanthroline)copper(II), the aldol condensation product of formaldehyde with the d- and l-(alaninato)aqua(1,10-phenanthroline)copper(II) nitrate

In this paper, we present our work on phase sensitive amplification performed in metastable helium at room temperature. The maximum obtainable gain is larger than 4.8 with a bandwidth of 100 kHz. © 2016 OSA.

2016 Conference on Lasers and Electro-Optics, CLEO 2016

Phase sensitive amplification in metastable helium at room temperature

One-electron oxidation of organoboron L2PhB: 1 (L = oxazol-2-ylidene) afforded a dicationic diborane(6) species [L2PhB-BPhL2]·2X (X = OTf, BF4, AlCl4) 3, representing a new strategy to construct a B(sp3)-B(sp3) covalent bond. Each boron atom in 3 is in the formal oxidation state +II, and tetracoordinate with a Ph group and two oxazol-2-ylidenes. The cyclic voltammetry of 3 shows irreversible reduction and oxidation. Indeed, two-electron reduction of 3 with potassium graphite (KC8) afforded 1, making a fully reversible 1 ↔ 3 redox system, whereas two-electron oxidation with AuCl produced a boronium [L2PhBCl]OTf 4. Moreover, the reactions of 3 with isonitrile derivatives RNC: under heating conditions gave a cyano-substituted boronium [L2PhBCN]BF4 5 and a 2-boranyl-indole derivative 6, depending on the substituent R. The proposed reaction mechanism involves a borinylium radical 1•+ which is generated via a homolytic cleavage of the B-B bond of 3. © 2016 American Chemical Society.

Journal of the American Chemical Society

Isolation of a Diborane(6) Dication: Formation and Cleavage of an Electron-Precise B(sp3)-B(sp3) Bond

This work expands on the recent synthesis and reactivity of the two-coordinate P(III)-containing dication [((Ph3P)2C)P(NiPr2)]2+ (3a2+). Two additional dications of general formula [((RPh2P)2C)P(NR′2)]2+ (3b2+, R = 1/2 (CH2)3, R′ = iPr; 3c2+, R = Ph, R′ = Cy) have been prepared. Solution and solid-state 31P NMR isotropic shifts for this dication class were observed around 360 ppm. Except for [3a][SbF6]2, the 31P CP/MAS NMR spectra reveal a high degree of structural disorder around the dicationic site in the solid state. Surprisingly, the synthesis of dication 3a2+ was only possible in the presence of AlCl4-, SbF6-, and substituted tetraarylborates, while the use of ClO4-, OTf-, BF4-, PF6-, and BPh4- resulted in complex product mixtures. Single-crystal X-ray analysis of dications 3a2+ and 3c2+ suggested a 4π allyl-like structure for the central CPN fragment, and this has been supported through detailed theoretical investigations. Initial reactivity studies between dications 3a2+/3c2+ and PMe3 show an equilibrium between the free dication and the target adduct. Furthermore, 3a2+ has been shown to be capable of O-H bond activation using water and methanol and polymerizes THF when it is dissolved in this solvent. © 2015 American Chemical Society.

Organometallics

Preparation, Structural Analysis, and Reactivity Studies of Phosphenium Dications

The reaction of germylone (L)Ge (1) [L = 3-Ad-1-{C(tBu) = N(Mes)}C3H4N2] with 1 equivalent of MeOTf afforded a germyliumylidene ion [(L)GeMe]+OTf- (2), while reactions with M(CO)5(thf) (M = Cr, Mo, W) gave the corresponding germylone-metal complexes [(L)Ge]M(CO)5 (3-5). The former possesses a pyramidal Ge center, whereas the latter display a planar geometry around the Ge atom. Computational studies showed a unique bonding interaction between 1 and the M(CO)5 unit, which involves a σ-donation as well as a weak π-back-donation. © The Royal Society of Chemistry 2016.

Fulltext

Chemical Communications

Synthesis, characterization, and electronic structures of a methyl germyliumylidene ion and germylone-group VI metal complexes

The reactions of equimolar amounts of trans-[ReOC13(PPh3)2] or trans-[Re(NPh)(PPh3)2Cl3] with a Schiff base formed by condensation of 2-hydroxy-4-methoxybenzaldehyde and ethanolamine (H2L) result in the formation of cis-[ReO(HL)PPh3Cl2] (1a) and trans-[Re(NPh)(HL)(PPh3)Cl2] (2b), respectively, in good yields. 1a and 2b have been characterized by a range of spectroscopic and analytical techniques. The X-ray crystal structures of 1a and 2b reveal that 1a is an octahedral cis-Cl,Cl oxorhenium(V) complex, while 2b is a trans-Cl,Cl phenylimidorhenium(V) complex. The complexes are weakly emissive at room temperature with quantum yields of 10-4. Density functional theory calculations of the electronic properties of the complexes were performed and are in agreement with the experimental results. The complexes display quasi-reversible Re(V)/Re(VI) redox couples in acetonitrile. There is reasonable agreement between the experimental and calculated redox potentials of 1a and 2b. © 2015 Taylor & Francis.

Journal of Coordination Chemistry

Synthesis and DFT calculations of oxido and phenylimido-rhenium(V) complexes incorporating the N, O donor ligand 2-[(2-hydroxyethylimino)methyl]phenol

The reaction of the N-heterocyclic-carbene-stabilized disilicon(0) complex [IPr→Si=Si←IPr] (1; IPr =:C{N(Ar)CH}2 and Ar = 2,6-iPr2C6H3) with ArN3 afforded the N-heterocyclic-carbene-stabilized siladiimide [ArNSi(IPr)NAr] (2). X-ray crystallography and theoretical studies show that the N-Si-N skeleton in compound 2 possesses considerable double-bond character and the Si atom is stabilized by the N-heterocyclic carbene. © 2015 American Chemical Society.

Inorganic Chemistry

Synthesis of an N-Heterocyclic-Carbene-Stabilized Siladiimide

A growing number of halogenated organic compounds have been identified as hazardous pollutants. Although numerous advanced oxidative processes have been developed to degrade organohalide compounds, reductive and nucleophilic molecular approaches to dehalogenate organic compounds have rarely been reported. In this manuscript, we employ nickel(ii)-ate complexes bearing the o-phenylenebis(N-methyloxamide) (Me2opba) tetraanionic ligand as nucleophilic reagents that can react with alkyl halides (methyl up to the bulky isobutyl) by O-alkylation to give their respective imidate products. Four new nickel(ii) complexes have been characterized by X-ray crystallography, and the salient structural parameters and FT-IR vibrational bands (∼1655 cm-1) concur with their assignment as the imidate tautomeric form. To the best of our knowledge, this is the first report on the nucleophilic reactivity of NiII(Me2opba) with halogenated organic compounds. The parent nickel(ii) Me2opba complex exhibits reversible electrochemical oxidation and reduction behavior. As a proof of concept, NiII(Me2opba) and its alkylated congeners were utilized for the electrocatalytic reduction of chloroform, as a representative, simple polyhalogenated organic molecule that could arise from the oxidative treatment of organic compounds by chlorination. Modest turnover numbers of up to 6 were recorded, with dichloromethane identified as one of the possible products. Future efforts are directed towards bulkier -ate complexes that possess metal-centered instead of ligand-centered nucleophilic activity to create more effective electrocatalysts for the reduction of halogenated organic compounds. © 2016 The Royal Society of Chemistry.

Dalton Transactions

Nucleophilic reactivity and electrocatalytic reduction of halogenated organic compounds by nickel: O -phenylenedioxamidate complexes

Boranes have long been known as the archetypal Lewis acids owing to an empty p-orbital on the boron centre. Meanwhile, Lewis basic tricoordinate boranes have been developed in recent years. Here we report the synthesis of an annulated 1,4,2,5-diazadiborinine derivative featuring boron atoms that exhibit both Lewis acidic and basic properties. Experimental and computational studies confirmed that two boron atoms in this molecule are spectroscopically equivalent. Nevertheless, this molecule cleaves C-O, B-H, Si-H and P-H bonds heterolytically, and readily undergoes [4+2] cycloaddition reaction with non-activated unsaturated bonds such as C=O, C=C, C ‰ C and C ‰ N bonds. The result, thus, indicates that the indistinguishable boron atoms in 1,4,2,5-diazadiborinine act as both nucleophilic and electrophilic centres, demonstrating ambiphilic nature.

Nature Communications

Ambiphilic boron in 1,4,2,5-diazadiborinine

The bis(alkynyl) iridium complexes [Cp∗Ir(L)(CCAr)2] undergo an Arbuzov-type reaction with phosphites to give four-membered iridacyclic phosphonates [Cp∗Ir(L){C(Ar)=C[P(=O)(OR)2]C=CHAr}]. These can isomerise to a five-membered iridafuran in the presence of a strong acid. In the absence of a phosphite, the bis(alkynyl) iridium complexes undergo acid-catalysed aerobic oxidation to form 1,2-diketone iridabenzofurans [Cp∗Ir(L){C6H4-1,2-CH=CC(=O)C(=O)Ar}]. A common reaction pathway involving initial protonation and alkynyl migration is proposed. © 2016 Elsevier B.V.