Zwitterionic Aqua Palladacycles with Noncovalent Interactions for meta-Selective Suzuki Coupling of 3,4-Dichlorophenol and 3,4-Dichlorobenzyl Alcohol in Water

The site-selective reaction of substrates with multiple reactive sites has been a focus of the current synthetic chemistry. The use of attractive noncovalent interactions between the catalyst and substrate is emerging as a versatile approach to address site-selectivity challenges. Herein, we designed and synthesized a series of palladacycles, to control meta-selective Suzuki coupling of 3,4-dichlorophenol and 3,4-dichlorobenzyl alcohol. Noncovalent interactions directed zwitterionic aqua palladacycles catalyzed meta-selective Suzuki couplings of 3,4-dichloroarenes bearing hydroxyl in water have been developed. Experiments and density functional theory (DFT) calculations demonstrated that the electrostatic interactions play a critical role in meta-selective coupling of 3,4-dichlorophenol, while meta-selective coupling of 3,4-dichlorobenzyl alcohol arises due to the hydrogen-bonding interactions.

A Second-Generation Palladacycle Architecture Bearing a N-Heterocyclic Carbene and Its Catalytic Behavior in Buchwald–Hartwig Amination Catalysis

Palladacyclic architectures have been shown as versatile motifs in cross-coupling reactions. NHC-ligated palladacycles possessing unique electronic and steric properties have helped to stabilize the catalytically active species and provide additional control over reaction selectivity. Here, we report on a synthetic protocol leading to palladacycle complexes using a mild base and an environmentally desirable solvent, with a focus on complexes bearing backbone-substituted N-heterocyclic carbene ligands. The readily accessible complexes exhibit high catalytic activity in the Buchwald–Hartwig amination. This is achieved using low catalyst loading and mild reaction conditions in a green solvent.

Fluorescent perylenylpyridine complexes: an experimental and theoretical study

The perylene derivative 2-(3-perylenyl)-4-methylpyridine (HPerPy) was prepared and used to synthesize [Ag(HPerPy)(PPh3)(OClO3)], with the perylene ligand bonded to the metal centre only by the pyridine nitrogen. The treatment of HPerPy with [Pd(OAc)2] in methanol or acetic acid led to acetate bridged dimers (μ-OOCCH3)2[Pd(PerPy)]2, six-membered or five-membered cycled at the perylenyl fragment. Substitution reactions afforded mononuclear compounds [Pd(PerPy)(acac)] (six-member or five-member cycled) and [Pd(PerPy)(S2COMe)] (six-member or five-member cycled). The reaction of HPerPy with a platinum(ii) fragment led to a five-membered cyclometallated Pt(ii) complex [Pt(PerPy)(acac)]. The oxidative addition with MeI gave the corresponding cyclometallated Pt(iv) compound [Pt(PerPy)(acac)MeI]. X-ray single crystal studies of compounds [Ag(HPerPy)(PPh3)(OClO3)], (μ-OOCCH3)2[Pd(PerPy)]2-five-membered, [Pd(PerPy)(acac)]-six-membered, [Pd(PerPy)(S2COMe)]-five-membered, [Pt(PerPy)(acac)]-five-membered, and [Pt(PerPy)(acac)MeI]-five-membered confirmed the proposed structures. The UV-Vis spectra show one intense absorption with vibronic coupling in the visible region with maxima in the range of 448-519 nm. DFT calculations were carried out for the absorption spectra of the HPerPy molecule and representative complexes [M(PerPy)(acac)] (M: Pd, Pt; five and six-membered isomers) and [Pt(PerPy)(acac)MeI], showing that the lowest energy most intense transition in the complexes corresponds to the HOMO → LUMO transition in the perylene moiety, although affected by the metallacycle size and the metal nature. All the compounds are fluorescent in solution, due to the perylene fragment. The emission spectra display maxima in the range of 468-549 nm, with quantum yields from 1.1 to 82%. The attenuation of the intensity of fluorescence by the presence of heavy atoms and the formation of metallacycles has been experimentally determined and sequenced.

Crystal structure of (η6-1-methyl-4-isopropylbenzene)-[5-bromo-2-(2-pyridyl)phenyl-κ2 C,N]-chloro-ruthenium(II), C21H21BrClNRu

C21H21BrClNRu, triclinic, P1̄ (no. 2), a = 8.2185(4) Å, b = 10.1626(5) Å, c = 11.9356(6) Å, α = 100.399(4)°, β = 90.005(4)°, γ = 93.434(4)°, V = 978.68(9) Å3, Z = 2, R gt(F) = 0.0353, wR ref(F 2) = 0.0676, T = 291(2) K.

A four-coordinate Cu(I)–N-heterocyclic carbene complex: Synthesis, structure, properties, and application in amination for the synthesis of 1-(2-N-heteroaryl)-1H-pyrazoles

A new luminescent, cationic, heteroleptic, four-coordinate Cu(I)– N-heterocyclic carbene complex [Cu(Br-Pyim)(POP)](PF6) is successfully prepared and characterized, where Br-Pyim and POP are 1-(6-bromopyridin-2-yl)imidazole-3-benzyl-2-ylidene and bis[2-(diphenylphosphino)phenyl]ether, respectively. Its detailed structure is determined by single-crystal X-ray analysis. It exists as a crystalline powder at room temperature and exhibits bright yellow-green emission. The use of the Cu(I)– N-heterocyclic carbene complex as a catalyst for amination reactions is also investigated and is found to be very efficient for the amination of 2- N-heteroaryl chlorides with pyrazoles, giving the desired substituted 1-(2- N-heteroaryl)-1 H-pyrazoles in good yields.

Crystal structure of chlorido (2-(4-ethylphenyl)pyrimidine-k2 C,N)(triphenylphosphane-kP) palladium(II), C30H26ClN2PPd

C30H26ClN2PPd, triclinic, P1̄ (no. 2), a = 9.1278(5) Å, b = 9.5892(7) Å, c = 15.5255(10) Å, α = 79.827(6)°, β = 89.131(5)°, γ = 78.358(5)°, V = 1309.74(14) Å3, Z = 2, R gt(F) = 0.0342, wR ref(F 2) = 0.0706, T = 291 K.

The crystal structure of dichlorobis(2-(dicyclohexylphosphino)-2′,4′,6′-tri-i-propyl-1,1′-biphenyl) palladium(II)-dichloroform, C68H100Cl8P2Pd

C68H100Cl8P2Pd, triclinic, P1̄ (no. 2), a = 9.6961(4) Å, b = 13.6069(6) Å, c = 15.1642(5) Å, α = 88.456(3)°, β = 72.251(3)°, γ = 72.376(4)°, V = 1811.64(12) Å3, Z = 1, R gt(F) = 0.0483, wR ref(F 2) = 0.1332, T = 291 K.

Crystal structure of chlorido-(4-chloro-6-(p-tolyl)pyrimidine-κ2 C,N)-(triphenylphosphane-κP)palladium(II), C29H23Cl2N2PPd

C29H23Cl2N2PPd, monoclinic, P21/c (no. 14), a = 9.4028(16) Å, b = 30.928(5) Å, c = 9.3071(16) Å, β = 103.222(2)°, V = 2634.8(8) Å3, Z = 4, R gt(F) = 0.0423, wR ref(F 2) = 0.1047, T = 296(2) K.

Crystal structure of 5-bromo-2-(naphthalen-6-yl)pyridine, C15H10BrN

C15H10BrN, monoclinic, P21/c (no. 14), a = 14.6998(9) Å, b = 5.9337(4) Å, c = 14.6275(11) Å, β = 113.542(8)°, V = 1169.67(15) Å3, Z = 4, R gt(F) = 0.0396, wR ref(F 2) = 0.1103, T = 293(2) K.

Theoretical prediction of the synthesis of 2,3-dihydropyridines through Ir(iii)-catalysed reaction of unsaturated oximes with alkenes

The Ir(iii)-catalysed reaction of unsaturated oximes with alkenes was predicted, and the results indicate a more efficient synthesis of 2,3-dihydropyridines.

Speciation of metal phosphonates with the assistance of weak interactions

By employing an aromatic methyl substituted V-shaped diphosphonic acid as a ligand, a series of metal diphosphonates, namely [Cu3(HL)2(H2O)2][(H2O)2] (1), [Cu(H2L)(pyz)(H2O)2][(H2O)2] (2), [Cu(H2L)(2,2'-bipy)] (3), [Cu(H2L)(4,4'-bipy)(H2O)2] (4), [Zn(H2L)(2,2'-bipy)] (5) and [Cd(H2L)(2,2'-bipy)(H2O)][(H2O)6] (6), have been synthesized. The structural studies reveal that these compounds exhibit diverse crystal structures. The introduction of the methyl group and pyridine derived auxiliary ligands results in the formation of plenty of C-HO, C-Hπ and ππ interactions, which contribute to the crystallization of metal diphosphonates. It was found that the Zn and Cd containing compounds showed intense intraligand emissions.

Crystal structure of [2-(4-methoxyphenyl)pyrazine-κ2 C,N) chlorido[N,N′-bis-(2,6-diisopropyl-phenyl)imidazol-2-ylidene-κC)] palladium(II), C38H45ClN4OPd

C38H45ClN4OPd, trigonal, R3m, a = 30.1968(8) Å, b = 30.1968(8) Å, c = 11.4611(3) Å, α = β = 90°, γ = 120.00°, V = 9050.7(4) Å3, Z = 9, R gt (F) = 0.0397, wR ref (F 2 ) = 0.1053, T = 291.15 K.

Non-covalent stacking interactions directing the structural and photophysical features of mono- and dinuclear cyclometalated palladium(ii) complexes

Cyclometallated Pd(ii) complexes with different stackings show emission in solid state in relationship to them.

Photoswitchable azobenzene-appended iridium(iii) complexes

The use of aliphatic-bridging units to append azobenzene fragments on triscyclometalated Ir(iii) complexes permits the construction of photoswitchable organometallics.

Synthesis of Ir(III) complexes with Tp(Me2) and acac ligands and their reactivity with electrophiles

The reaction of the bis(ethylene) complex [Tp(Me2)Ir(C2H4)2] () (Tp(Me2) = hydrotris(3,5-dimethylpyrazolyl)borate) with an excess of 2,4-pentanedione (acetylacetone, Hacac) at 70 °C produced a mixture of the Ir(iii) complex [Tp(Me2)Ir(acac)(C2H5)] () as a major product (67% yield) and two other side complexes [Tp(Me2)Ir(acac)(H)] () and [Tp(Me2)Ir(C9H14O2)] () in 20 and 13% yields, respectively. According to the proposed reaction mechanism and DFT calculations, complexes and are generated from an 18e(-) intermediate [Tp(Me2)Ir(C2H4)(acac)(C2H3)] () which undergoes either hydrogen insertion or β-hydride elimination followed by the subsequent loss of a molecule of ethylene. The lowest yielding complex which features a 2-iridafuran is presumably generated from an unusual thermal coupling between one vinylic and one acac moiety. The availability of the acidic α-proton of the acac ligand was tested by the treatment of complex with Br2 and Cu(NO3)2 rendering the substitution complexes [Tp(3-Br,Me2)Ir(3-Br-acac)Br] () and [Tp(Me2)Ir(3-NO2-acac)(C2H5)] () in good yields. The series of heteroleptic iridium(iii) compounds display air and moisture stability and have been characterized by NMR, IR, and elemental analyses, and, in the case of , and , by single-crystal X-ray diffraction analyses.

Synthesis of new heteroscorpionate iridium(i) and iridium(iii) complexes

The reactivity of different heteroscorpionate ligands based on bis(pyrazol-1-yl)methane, with different iridium-(i) and -(iii) precursors is reported.

Azobenzene-functionalized iridium(iii) triscyclometalated complexes

Photochromic triscyclometalated iridium(iii) organometallic complexes based on azobenzene-containing phenylpyridyl-type ligands.

Formylated chloro-bridged iridium(iii) dimers as OLED materials: opening up new possibilities

In this study, a series of four formyl-substituted chloro-bridged iridium(iii) dimers were prepared.