2633-66-1Relevant articles and documents
Backbone Boron-Functionalized Imidazoles/Imidazolium Salts: Synthesis, Structure, Metalation Studies, and Fluoride Sensing Properties
Anantharaman, Ganapathi,Avinash, Iruthayaraj,Parveen, Sabeeha
, (2020)
Incorporation of a Lewis acidic BMes2 (Mes = mesityl) moiety at the backbone of the imidazole ring was achieved by metal-halogen exchange procedure. Among them, two isomeric boron-phosphine functionalized imidazoles (3 and 6), monoboron-functionalized imidazoles (4 and 5), and its corresponding imidazolium salts were synthesized and thoroughly characterized. The solid-state structure of 3 reveals a dimeric B-N adduct that possesses six-membered [C-B-N]2 ring, and 5 crystallizes as tetrameric B-N adduct that forms an interesting 16-membered macrocycle, whereas 4 and 6 were obtained as monomeric BMes2-substituted imidazoles. 6 behaves as a P^N-type ligand upon the coordination with CuI to afford luminescent L2Cu4I4-type metal complexes (10 and 11) whose photophysical properties were also studied. The presence (in 10) and the absence (in 11) of BMes2 made a remarkable impact on fluorescence emission causing shift from the green (10) to orange (11) region. The fluoride sensing properties of BMes2-containing imidazoles (4 to 9) were studied using UV-vis and fluorescence spectroscopy.
A combined m?ssbauer, magnetic circular dichroism, and density functional theory approach for iron cross-coupling catalysis: Electronic structure, in situ formation, and reactivity of iron-mesityl-bisphosphines
Daifuku, Stephanie L.,Al-Afyouni, Malik H.,Snyder, Benjamin E. R.,Kneebone, Jared L.,Neidig, Michael L.
, p. 9132 - 9143 (2014/07/08)
While iron-bisphosphines have emerged as effective catalysts for C-C cross-coupling, the nature of the in situ formed iron species, elucidation of the active catalysts and the mechanisms of catalysis have remained elusive. A combination of 57Fe M?ssbauer and magnetic circular dichroism (MCD) spectroscopies of well-defined and in situ formed mesityl-iron(II)-SciOPP species combined with density functional theory (DFT) investigations provides the first direct insight into electronic structure, bonding and in situ speciation of mesityl-iron(II)-bisphosphines in the Kumada cross-coupling of MesMgBr and primary alkyl halides using FeCl2(SciOPP). Combined with freeze-trapped solution M?ssbauer studies of reactions with primary alkyl halides, these studies demonstrate that distorted square-planar FeMes 2(SciOPP) is the active catalyst for cross-coupling and provide insight into the molecular-level mechanism of catalysis. These studies also define the effects of key reaction protocol details, including the role of the slow Grignard addition method and the addition of excess SciOPP ligand, in leading to high product yields and selectivities.
Cyclometalated iridium complexes of bis(aryl) phosphine ligands: Catalytic C-H/C-D exchanges and C-C coupling reactions
Campos, Jesus,Espada, Maria F.,Lopez-Serrano, Joaquin,Carmona, Ernesto
supporting information, p. 6694 - 6704 (2013/07/19)
This work details the synthesis and structural identification of a series of complexes of the (η5-C5Me5)Ir(III) unit coordinated to cyclometalated bis(aryl)phosphine ligands, PR′(Ar) 2, for R′ = Me and Ar = 2,4,6-Me3C6H 2, 1b; 2,6-Me2-4-OMe-C6H2, 1c; 2,6-Me2-4-F-C6H2, 1d; R′ = Et, Ar = 2,6-Me2C6H3, 1e. Both chloride-and hydride-containing compounds, 2b-2e and 3b-3e, respectively, are described. Reactions of chlorides 2 with NaBArF (BArF = B(3,5-C 6H3(CF3)2)4) in the presence of CO form cationic carbonyl complexes, 4+, with ν(CO) values in the narrow interval 2030-2040 cm-1, indicating similar π-basicity of the Ir(III) center of these complexes. In the absence of CO, NaBArF forces κ4-P,C,C′,C″ coordination of the metalated arm (studied for the selected complexes 5b, 5d, and 5e), a binding mode so far encountered only when the phosphine contains two benzylic groups. A base-catalyzed intramolecular, dehydrogenative, C-C coupling reaction converts the κ4 species 5d and 5e into the corresponding hydrido phosphepine complexes 6d and 6e. Using CD3OD as the source of deuterium, the chlorides 2 undergo deuteration of their 11 benzylic positions whereas hydrides 3 experience only D incorporation into the Ir-H and Ir-CH 2 sites. Mechanistic schemes that explain this diversity have come to light thanks to experimental and theoretical DFT studies that are also reported.
