Structure, Spectra, and DFT Simulation of Nickel Benzazolate Complexes with Tris(2-aminoethyl)amine Ligand

Benzazolate complexes of Ni­(II), [Ni­(pbz)­(tren)]­ClO₄ (pbz = 2-(2′-hydroxyphenyl)-benzimidazole (pbm), <b>1</b>, 2-(2′-hydroxyphenyl)-benzoxazole (pbx), <b>2</b>, 2-(2′-hydroxyphenyl)-benzothiazole (pbt), <b>3</b>; tren = tris­(2-aminoethyl)­amine), are prepared by self-assembly reaction and structurally characterized. Theoretical DFT simulations are carried out to reproduce the features of their crystal structures and their spectroscopic and photophysic properties. The three complexes are moderately luminescent at room temperature both in acetonitrile solution and in the solid state. The simulations indicate that the absorption spectrum is dominated by two well-defined transitions, and the electronic density concentrates in three MOs around the benzazole ligands. The Stokes shifts of the emission spectra of complexes <b>1</b>–<b>3</b> are determined by optimizing the electronic excited state

Structure–Property Correlation behind the High Mobility of Carbazolocarbazole

A comparative study of carbazolocarbazole isomers and their respective <i>N</i>-alkyl derivatives confirms the good performance of carbazolo­[2,1-<i>a</i>]­carbazole as hole-transporting material in organic field effect transistors. The azaphenacene structure of this molecule forms a dense packing promoted by particularly short longitudinal shifts between molecules establishing face-to-face and edge-to-face interactions. Computational calculations have determined an almost isotropic 2D transport environment within a lamellar structure. This favorable solid state arrangement, in combination with appropriate interfacial layers, has led to a high mobility (1.3 cm² V^–1 s^–1) that validates the aptitude of this molecular material as an organic semiconductor

Structure and Spectroscopic Properties of Nickel Benzazolate Complexes with Hydrotris(pyrazolyl)borate Ligand

The reaction of benzazole ligands 2-(2′-hydroxylphenyl)­benzimidazole (Hpbm), 2-(2′-hydroxylphenyl)­benzoxazole (Hpbx), and 2-(2′-hydroxylphenyl)­benzothiazole (Hpbt), with [Ni­(Tp*)­(μ-OH)]₂ (Tp* = hydrotris­(3,5-dimethylpyrazolyl)­borate), leads to pentacoordinate nickel complexes [Ni­(Tp*)­(pbz)] (pbz = pbm (<b>1</b>), pbx (<b>2</b>), pbt (<b>3</b>)). The structures of <b>1</b>, <b>2</b>, and <b>3</b> were determined by X-ray crystallography. The pentacoordinate nickel complexes have distorted trigonal bipyramidal geometries with Addison’s τ parameter values of 0.63, 0.73, and 0.61 for <b>1</b>, <b>2</b> and <b>3</b>, respectively. The benzazolates are bonded in an η²(N,O) fashion to the nickel atoms. DFT calculations are carried out to optimize the structures of the three complexes giving a good agreement with the X-ray structures. The ¹H NMR spectra of complexes <b>1</b>–<b>3</b> exhibit sharp isotropically shifted signals. The complete assignment of these signals required an application of two-dimensional {¹H–¹H}-COSY techniques. The experimental absorption spectra of the three complexes in chloroform solution each show an intense absorption band in the ultraviolet region ca. 240 nm, followed by three less intense bands, the first two at ∼295 and ∼340 nm, and the last more disperse one, at wavelengths between 360 and 410 nm. The absorption spectra are simulated by TD-DFT and reproduce the main features of the experimental spectra well. The analysis of the electronic transitions by inspection of the frontier molecular orbitals and also the natural transition orbitals allowed us to characterize and assign the observed bands properly. The three complexes are moderately blue luminescent at room temperature, both in the solid state and in solution. Emission spectra at room temperature display broad structureless bands in chloroform solution at 460, 482, and 512 nm for complexes <b>1</b>, <b>2</b> and <b>3</b>, respectively, and structured emission in solid state with λ_max values of 473, 486, and 516 nm. Complexes containing different donor atoms in the benzazole ligand are furthermore observed to give different luminescence responses in the presence of Zn­(II), Cd­(II), Hg­(II), and Cu­(II)

N‑Heterocyclic-Carbene Complexes Readily Prepared from Di-μ-hydroxopalladacycles Catalyze the Suzuki Arylation of 9‑Bromophenanthrene

New cyclometalated palladium complexes of general formula [Pd­(Bmim)­(X)­(C^∧N)] have been synthesized by a novel reaction route involving di-μ-hydroxo-palladacycles [{Pd­(μ-OH)­(C^∧N)}₂] (C^∧N = 2-benzoylpyridine (Bzpy), <b>I</b>, previously unreported, or C^∧N = 2-phenylpyridine (Phpy), <b>II</b>)] and 1,3-butylmethyl­imidazolium salts [HBmim]­X (X: Cl, Br, I, or saccharinate (Sacc); <b>a</b>, <b>b</b>, <b>c</b>, or <b>d</b> complexes, respectively). This simple acid–base reaction could not be achieved under identical conditions when corresponding di-μ-acetate complexes were used as starting materials. An alternative pathway to NHC/imidate complexes has also been explored by reacting <b>IIb</b> with [Ag­(Phthal)­(SMe₂)]₂ (Phthal = phthalimidate, <b>e</b>) to obtain [Pd­(Bmim)­(Phthal)­(Phpy)], <b>IIe</b>. Structural characterization by X-ray diffraction of complexes <b>Id</b>, <b>IIb</b>, <b>IId</b>, and <b>IIe</b> has confirmed the proposed formulas. The mononuclear complexes have shown to catalyze the scalable Suzuki–Miyaura cross-coupling of 9-bromophenanthrene with a wide scope of aryl boronic acids, irrespective of their electronic properties and at a very low catalyst concentration of 0.01%

N‑Heterocyclic-Carbene Complexes Readily Prepared from Di-μ-hydroxopalladacycles Catalyze the Suzuki Arylation of 9‑Bromophenanthrene

New cyclometalated palladium complexes of general formula [Pd­(Bmim)­(X)­(C^∧N)] have been synthesized by a novel reaction route involving di-μ-hydroxo-palladacycles [{Pd­(μ-OH)­(C^∧N)}₂] (C^∧N = 2-benzoylpyridine (Bzpy), <b>I</b>, previously unreported, or C^∧N = 2-phenylpyridine (Phpy), <b>II</b>)] and 1,3-butylmethyl­imidazolium salts [HBmim]­X (X: Cl, Br, I, or saccharinate (Sacc); <b>a</b>, <b>b</b>, <b>c</b>, or <b>d</b> complexes, respectively). This simple acid–base reaction could not be achieved under identical conditions when corresponding di-μ-acetate complexes were used as starting materials. An alternative pathway to NHC/imidate complexes has also been explored by reacting <b>IIb</b> with [Ag­(Phthal)­(SMe₂)]₂ (Phthal = phthalimidate, <b>e</b>) to obtain [Pd­(Bmim)­(Phthal)­(Phpy)], <b>IIe</b>. Structural characterization by X-ray diffraction of complexes <b>Id</b>, <b>IIb</b>, <b>IId</b>, and <b>IIe</b> has confirmed the proposed formulas. The mononuclear complexes have shown to catalyze the scalable Suzuki–Miyaura cross-coupling of 9-bromophenanthrene with a wide scope of aryl boronic acids, irrespective of their electronic properties and at a very low catalyst concentration of 0.01%