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In recent years, the hyperpolarization method Signal Amplification By Reversible Exchange (SABRE) has developed into a powerful technique to enhance Nuclear Magnetic Resonance (NMR) signals of organic substrates in solution (mostly via binding to the nitrogen lone pair of N-heterocyclic compounds) by several orders of magnitude. In order to establish the application and development of SABRE as a hyperpolarization method for medical imaging, the separation of the Ir-N-Heterocyclic Carbene (Ir-NHC) complex, which facilitates the hyperpolarization of the substrates in solution, is indispensable. Here, we report for the first time the use of novel Ir-NHC complexes with a polymer unit substitution in the backbone of N-Heterocyclic Carbenes (NHC) for SABRE hyperpolarization, which permits the removal of the complexes from solution after the hyperpolarization of a target substrate has been generated. [ABSTRACT FROM AUTHOR]

A new imidazolium salt 3⋅HI with 8‐Bodipy as one N‐aryl substituent was synthesized from 8‐chloro‐Bodipy and imidazole followed by alkylation with iPrI. NHC‐metal complexes [CuCl(3)], [AuCl(3)], [Pd(allyl)Cl(3)] and [MCl(cod)(3)] and [MCl(CO)2(3)] (M=Rh, Ir) were synthesized and the X‐ray crystal structure of [IrCl(CO)2(3)] determined. The donation of NHC 3 was determined via IR (ν(CO) and cyclic voltammetry (Ir(I/II) redox potential). The photosensitizing properties of the complexes for the generation of 1O2 were quantified observing singlet oxygen quantum yield of up to Φs.o.=0.63. [IrCl(cod)(3)] displays poor Φs.o.=0.09, but, following a simple ligand exchange reaction of cod by two CO [IrCl(CO)2(3)], a pronounced increase to Φs.o.=0.63 is observed. [ABSTRACT FROM AUTHOR]

A new imidazolium salt 3⋅HI with 8‐Bodipy as one N‐aryl substituent was synthesized from 8‐chloro‐Bodipy and imidazole followed by alkylation with iPrI. NHC‐metal complexes [CuCl(3)], [AuCl(3)], [Pd(allyl)Cl(3)] and [MCl(cod)(3)] and [MCl(CO)2(3)] (M=Rh, Ir) were synthesized and the X‐ray crystal structure of [IrCl(CO)2(3)] determined. The donation of NHC 3 was determined via IR (ν(CO) and cyclic voltammetry (Ir(I/II) redox potential). The photosensitizing properties of the complexes for the generation of 1O2 were quantified observing singlet oxygen quantum yield of up to Φs.o.=0.63. [IrCl(cod)(3)] displays poor Φs.o.=0.09, but, following a simple ligand exchange reaction of cod by two CO [IrCl(CO)2(3)], a pronounced increase to Φs.o.=0.63 is observed. [ABSTRACT FROM AUTHOR]

The direct arylation of 1,3‐benzodioxole and 2,2‐difluorobenzo[1,3]dioxole with 26 different aryl bromides yields the respective 4‐substitued products in yields of >80% requiring between 0.05–1 mol % Na2PdCl4, 30 mol % pivalic acid, 1.3 equivs. K2CO3 and ca. 250 equivs. of diethylacetamide per Pd at T=120 °C. The nature of the amide and the concentration of the reactants are crucial for the optimization of the reaction conditions. The primary role of the acetamide is that of a ligand to Pd, it is not needed as a solvent. [ABSTRACT FROM AUTHOR]

The characterization of novel fluoro-m-cyclophane-based cryptands with two fluorocarbon donors is described as well as the investigation of the coordination chemistry of such ligands with alkaline earth metal ions and alkali. Results reveal substantial shifts of the F nuclear magnetic resonances. There is also ample evidence to show a close relationship between conventional cryptands and fluoro, both of which display the preference for the same metal ions.

Carbon-fluorine (CF) units can be suitable donors in interactions with metal ions, such as lithium and other alkali and alkaline earth metals. Coordination of CF-metal chemistry requires that ligands contain an abundance of fluorine atoms and few other donors, as interactions will favor oxygen when available. Electronegativity of the ligand and preorganization of donor atoms improves interaction with metallic cations.

The reaction of 1,3-bis(bromomethyl)-2-fluorobenzene with diaza-18-crown-6 produced novel fluoro cryptands and fluoro crown ethers in excellent yields. Analysis of the stability constants of the metal complexes of the fluoromacrocycles of these ethers and their fluorine free relatives suggests that the fluorine-containing macrocycles formed more stable metal complexes than the analogous fluorine free systems.

Synthesis of two fluorine containing macrocycles involves the use of tetrafluoro-1, 2-bis(chlorosulfenyl)ethane as a building block. One of the partially fluorinated compounds is a fluorinated analogue of the (2S.2O.2O) cryptand. Addition of alkali metal ions to the partially fluorinated cryptand produces stable complexes and complexation leads to shift in the position of the 19F NMR resonances. X-ray studies enable the determination of the structure of a sodium complex.

Cyclic voltammetric studies of the redox potentials of 22 ferrocene nitrogen compounds help analyze redox-switched bonding of cations to ferrocene crown ethers. X-ray studies help characterize diprotonated, methylated and dimethylated ferrocene compounds. Structure and redox potentials reveal a linear relationship between inverse ion-nitrogen separation and redox potential shift that helps determine the structure of protonated isomers of ferrocenes.

The creation of N-substituted crown ethers carrying a substituted cyclopentadiene or indene in a pendant side arm results in the formation of crown-ether-substituted cyclopentadiene ligands. The ligands catalyze transition metal coordination sphere substitutions despite the destabilization effects of crown-ether subunits. The crown-ether units strongly influence organometallic group behavior. Metals can be bound to heterotopic ligand faces by eta to the power 5 cyclopentadienyl bonding or as sigma-donor crown ether units.

A highly efficient Suzuki-Miyaura cross-coupling protocol is developed, which facilitates the conversion of N-hetero- and normal aryl chlorides with thiophene- and furanboronic acids in aqueous n-butanol as the solvent. The coupling reaction based on Pd complex of the highly water soluble disulfonated fluorenylphosphine could be used for large scale product separation without the need for additional organic solvents during reaction process.

A new N,N'-bis(triptycenyl)-NHC ligand with methyl groups in the ortho position has been synthesized starting from 2,3-dimethyltriptycene-1,4-quinone. The respective metal complexes [ML(NHC)] [ML = CuBr, AuCl, PdCl(allyl), RhCl(cod), IrCl(cod), RhCl(CO)2, IrCl(CO)2, and RuCl2(=CHC6H4OiPr)] were obtained by standard procedures. All the complexes were initially mixtures of syn and anti isomers. The ruthenium complex was separated into the syn and anti isomers. The crystal structure of the anti complex [RhCl(cod)(8)] has been determined. [ABSTRACT FROM AUTHOR]