We have developed a nickel-catalyzed cross coupling of benzylic ammonium triflates with aryl boronic acids to afford diarylmethanes and diarylethanes. This reaction proceeds under mild reaction conditions and with exceptional functional group tolerance. Further, it transforms branched benzylic ammonium salts to diarylethanes with excellent chirality transfer, offering a new strategy for the synthesis of highly enantioenriched diarylethanes from readily available chiral benzylic amines.

A copper(I) iminopyrrolidinate was synthesized and evaluated by thermal gravimetric analysis (TGA), solution based (1)H NMR studies and surface chemistry to determine its thermal stability and decomposition mechanism. Copper(I) tert-butyl-imino-2,2-dimethylpyrrolidinate (1) demonstrated superior thermal stability and showed negligible decomposition in TGA experiments up to 300 °C as well as no decomposition in solutions at 165 °C over 3 weeks.

Dimeric silver(I) and gold(I) tert-butyl-imino-2,2-dimethylpyrrolidinates were synthesized and characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), single-crystal X-ray diffraction, and chemical vapor deposition (CVD) experiments. The motivation for this work arose from the excellent thermal stability of the previously reported analogous copper(I) compound and included the completion of a series of potential precursors for atomic layer deposition. These compounds are stable in air and soluble in aromatic or chlorinated solvents. In the solid state, TGA and DSC showed these compounds to be thermally stable up to 170 °C and to have good evaporation yields up to 240 °C. Gas phase decomposition temperatures were 140 °C for the silver compound and 300 °C for the gold compound, as determined by CVD experiments, where these compounds decomposed to produce metallic films. Reduction of the metal ions via dehydrogenation of the ligands is proposed as a thermolysis pathway.

Access to the full text of the published version may require a subscription. Rights AbstractTwo novel N-heterocyclic carbene (NHC)-containing copper(I) amides are reported as atomic layer deposition (ALD) precursors. 1,3-diisopropyl-imidazolin-2-ylidene copper hexamethyldisilazide (1) and 4,5-dimethyl-1,3-diisopropyl-imidazol-2-ylidene copper hexamethyldisilazide (2) were synthesized and structurally characterized. The thermal behaviour of both compounds was studied by thermogravimetric analysis (TGA), and they were both found to be reasonably volatile compounds. Compound 1 had no residual mass in the TGA and showed long-term stability at temperatures as high as 130 °C, while 2 had a residual mass of 7.4 %. Copper metal with good resistivity was deposited using 1 by plasma-enhanced atomic layer deposition. The precursor demonstrated self-limiting behaviour indicative of ALD, and gave a growth rate of 0.2 Å/cycle. Compound 2 was unsuccessful as an ALD precursor under similar conditions. Density functional theory calculations showed that both compounds adsorb dissociatively onto a growing copper film as long as there is some atomic roughness, via cleavage of the Cu-carbene bond.

The thermal properties of a series of monomeric copper(I) hexamethyldisilazide complexes supported by N-heterocyclic and acyclic diamino carbenes were evaluated to study the impact of N-alkyl substituents and backbone character on volatility and thermal stability of copper amides. The series of complexes were either liquids or solids with melting points in the broad range of 45−184 °C. Vaporization rates were measured by stepped-isothermal TGA experiments and found to be between 110−170 °C. Enthalpies of vaporization were determined to be 63−90 kJ/mol. Temperatures for 1 Torr vapor pressure were estimated to be 143−172 °C, showing a general dependence on molecular weight. The imidazolylidene complexes were thermally unstable with convincing evidence indicating the unsaturated backbone as a point of weakness. The imidazolinylidene complexes showed excellent thermal stability with comparable results for the formamidinylidenes complexes. The steric parameter of the carbene, %V Bur , was calculated for all complexes characterized by single crystal X-ray diffraction.