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Single-electron oxidation of neutral boryl-linked tetraaminoethylene derivatives 4 led to the formation of radical cations 4+, which have been isolated and fully characterized. X-ray diffraction analysis, EPR spectroscopy, and computational studies revealed that the unpaired electron is delocalized over the B2N4C2 skeleton and the spin density mainly resides on the carbon and boron atoms. © 2017 The Royal Society of Chemistry.

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Chemical Science

Crystalline boron-linked tetraaminoethylene radical cations

The reaction of the pentaphenylborole [(PhC)4BPh] (1) with sodium phosphaethynolate·1,4-dioxane (NaOCP(1,4-dioxane)1.7) afforded the novel sodium salt of phosphaboraheterocycle 2. It comprises anionic fused tetracyclic P/B-heterocycles that arise from multiple bond activation between the borole backbone and [OCP]−anion. Density functional theory calculations indicate that the [OCP]− anion prefers the form of phosphaethynolate -O-CP over phosphaketenide OCP- to interact with two molecules of 1, along with various B-C, C-P, and C-C bond activations to form 2. The calculations were verified by experimental studies: (i) the reaction of 1 with NaOCP(1,4-dioxane)1.7 and a Lewis base such as the N-heterocyclic carbene IAr [:C{N(Ar)CH}2] (Ar = 2,6-iPr2C6H3) and amidinato amidosilylene [{PhC(NtBu)2}(Me2N)Si:] afforded the Lewis base-pentaphenylborole adducts [(PhC)4B(Ph)(LB)] (LB = IAr (3), :Si(NMe2){(NtBu)2CPh} (4)), respectively; (ii) the reaction of 1 with the carbodiimide ArNCNAr afforded the seven-membered B/N heterocycle [B(Ph) (CPh)4C(NAr)N(Ar)] (5). Compounds 2-5 were fully characterized by NMR spectroscopy and X-ray crystallography. © 2017 American Chemical Society.

Inorganic Chemistry

Diverse Bonding Activations in the Reactivity of a Pentaphenylborole toward Sodium Phosphaethynolate: Heterocycle Synthesis and Mechanistic Studies

Three new mononuclear square planar Ni(II) complexes, containing pincer type tridentate Schiff base ligands, having general formula [(NiL1(4-MePy)] (1), [(NiL1(2-AzNp)] (2), and [(NiL2(4-MePy)] (3) [where L1 = anion of N-(2-hydroxy-3-methoxybenzylidene) benzoylhydrazide (HL1), L2 = anion of N-(2-hydroxy-3-methoxybenzylidene) thiosemicarbazide (HL2), 4-MePy = 4-Methylpyridine and 2-AzNp = 2-Azanapthalene] have been synthesized and fully characterized by FT-IR, UV–visible, NMR, single crystal X-ray diffraction studies and elemental analysis. All the three complexes show square planar geometry around the nickel atom. The pincer type ligand occupies three coordination sites, while the fourth site is occupied by the monodentate nitrogen containing ligand. The Quantum chemical DFT calculations have also been carried out using DFT/B3LYP method and 6-311++G(d,p) basis set. The synthesized nickel complexes were screened for antimicrobial activities by agar well diffusion method against E. coli bacteria. Out of three complexes, [(NiL2(4-MePy)] (3) only showed the antimicrobial activity against E. coli bacteria. © 2017 Elsevier B.V.

Journal of Molecular Structure

Synthesis, spectroscopic and single crystal X-ray studies on three new mononuclear Ni(II) pincer type complexes: DFT calculations and their antimicrobial activities

Diverse skeletal transformations of 1,4,2-diazaboroles through ring expansion, photoisomerization, and retrocyclization led to the isolation of various B,N-dihydroindole (compounds 3 and 6), 1,3-azaborolidin-2-imine (compound 7), and 1,4,2-diazaborol-3-imine derivatives (compound 11). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Angewandte Chemie - International Edition

Ring Expansion, Photoisomerization, and Retrocyclization of 1,4,2-Diazaboroles

The thermal reaction of Ru3(CO)12 (1) with salicylic acid, in the presence of triphenylphosphine, pyridine, or dimethylsulfoxide, afforded the dinuclear complexes Ru2(CO)4(μ-O2CC6H4OH)2L2 (2) [L = PPh3 (2a). C5H5N (2b); (CH3)2SO (2c)]. Complex 2b was further reacted with the aromatic dimmines 2,2′-dipyridine or 1,10-phenanthroline to give the cationic diruthenium complexes [Ru2(CO)2(μ-CO)2(μ-O2CC6H4OH)(N∩N)2]+ (3) [(N∩N) = 2,2′-dipyridine (3a); 1,10-phenanthroline (3b)], which were isolated as their tetraphenylborate salts. All five novel complexes were characterized spectroscopically and analytically. For 2a–2b and 3a–3b, single-crystal X-ray diffraction studies were also carried out. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Zeitschrift fur Anorganische und Allgemeine Chemie

Synthesis, Characterization, and Crystal Structures of Diruthenium Complexes Containing Bridging Salicylato Ligands

The LUMO of [CF3P−W(CO)5] is lower in energy than the LUMO of [ClP−W(CO)5] by 0.30 eV and [CF3P−W(CO)5] is the most electrophilic phosphinidene tungstenpentacarbonyl complex described so far. It is generated by reaction of dimethyl acetylenedicarboxylate with the appropriate 1-trifluoromethylphosphole complex at 80 oC in toluene. It reacts normally with alkynes to give 1-trifluoromethylphosphirene complexes. The reaction with alkenes works only with electron-rich species. The phosphirane complexes appear to be unstable when electron-poor C=C double bonds are used such as with trans-stilbene. This highlights the importance of the P to C=C backbonding in the stability of the phosphirane adducts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ChemistrySelect

Generation and Trapping of Terminal Phosphinidene Complex [CF3P-W(CO)5]

A new broadband-emitting 2 D hybrid organic–inorganic perovskite (CyBMA)PbBr4 based on highly flexible cis-1,3-bis(methylaminohydrobromide)cyclohexane (CyBMABr) core has been designed, synthesized, and investigated, highlighting the effects of stereoisomerism of the templating cation on the formation and properties of the resulting perovskite. The new 2 D material has high exciton binding energy of 340 meV and a broad emission spanning from 380 to 750 nm, incorporating a prominent excitonic band and a less intense broad peak at room temperature. Significant changes in the photoluminescence (PL) spectrum were observed at lower temperatures, showing remarkable enhancement in the intensity of the broadband at the cost of excitonic emission. Temperature-dependent PL mapping indicates the effective role of only a narrow band of excitonic absorption in the generation of the active channel for emission. Based on the evidences obtained from the photophysical investigations, we attributed the evolution of the broad B-band of (CyBMA)PbBr4 to excitonic self-trapped states. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ChemSusChem

Broadband-Emitting 2 D Hybrid Organic–Inorganic Perovskite Based on Cyclohexane-bis(methylamonium) Cation

1,3-Dipolar cycloaddition between nickel-ligated azide in [NiL(N3)] [HL = 3-(2-diethylamino-ethylimino)-1-phenyl-butan-1-one] and two different organonitriles furnished two new square-planar complexes viz. [NiL(5-phenyltetrazolato)] and [NiL{5-(4-pyridyl)-tetrazolato}]. Both the complexes have been characterized by spectroscopic tools and single-crystal X-ray crystallography. Interaction with different biomolecules revealed that both complexes bind strongly to serum albumin proteins and show moderate catecholase-like activity by catalyzing the oxidation of 3,5-ditertbutylcatechol (3,5-DTBC). Identification of intermediates formed in catechol oxidation has been explored by ESI-MS spectrometry. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

Journal of Coordination Chemistry

Nickel tetrazolato complexes synthesized by microwave irradiation: Catecholase like activity and interaction with biomolecules

Visible light assisted photocatalytic organic reactions have recently received intense attention as a versatile approach to achieve selective chemical transformations, including C-C and several C-X (X = N, O, S) bond formations under mild reaction conditions. The light harvesters in previous reports predominantly comprise ruthenium or iridium photosensitizers. In contrast, selective, photocatalytic aliphatic C-C bond cleavage reactions are scarce. The present study focuses on rationally designing VV oxo complexes as molecular, photoredox catalysts toward the selective activation and cleavage of a C-C bond adjacent to the alcohol group in aliphatic alcoholic substrates. We have employed kinetics measurements and DFT calculations to develop a candidate for the catalytic C-C bond activation reaction that is up to 7 times faster than our original vanadium complex. We have also identified a substrate where the C-C bond cleaves at rates 2.5-17 times faster, depending on the catalyst used. In order to better understand the effects of ligand modification on the thermodynamics and catalysis, DFT calculations were employed to reveal the orbital energies, the electronic transitions during the C-C bond cleavage, and the activation barriers. Our combined kinetics and computational studies indicate that the incorporation of electron-withdrawing groups at select sites of the ligand is essential for the development of active and stable vanadium photocatalysts for our C-C bond cleavage reactions. © 2017 American Chemical Society.

ACS Catalysis

Kinetics and DFT Studies of Photoredox Carbon-Carbon Bond Cleavage Reactions by Molecular Vanadium Catalysts under Ambient Conditions

A new Cu(II) complex [Cu(cyhxn)2(H2O)2][OTf]2 was synthesised by the reaction of ligand cyhxn (cyhxn = trans-cyclohexane-1,2-diamine) with Cu(OTf)2 in methanol at room temperature. The complex was fully characterized by elemental analysis (CHN), FT-IR, UV–Vis and EPR spectroscopic techniques. The structure of the complex was confirmed by single crystal X-ray diffraction study. The EPR spectrum is isotropic type having giso = 2.078, which indicates a distorted octahedral geometry of the complex. The complex was found to be an active homogeneous catalyst for the homocoupling reactions of arylboronic acid to obtain symmetrical biaryls at room temperature in methanol without the use of any additives such as a base and or an oxidant. © 2016 Elsevier B.V.