Covalent organic frameworks constitute a subclass of polymeric materials offering enhanced porosity, functionality and stability. In this work a covalent triazine framework based on bipyridine building blocks is presented, along with a comprehensive elucidation of its local structure, porosity, and capacity for metal uptake. A typical synthesis was carried out under ionothermal conditions at 400 700 C using ZnCl 2 as a Lewis acidic trimerization catalyst. A high degree of local order and the presence of triazine and bipyridine moieties are ascertained at a synthesis temperature of 400 C, along with micropores and specific surface areas of up to 1100 m 2 g 1 . Mesopores are increasingly formed at synthesis temperatures above 450 C, yielding highly porous frameworks with hierarchical porosity and exceptionally large surface areas in excess of 3200 m 2 g 1 at 700 C. We demonstrate the capability of the bipyridine unit to provide specific and strong binding sites for a large variety of transition metal ions, including Co, Ni, Pt and Pd. The degree of metal loading (up to 38 wt%) can be tuned by the metal concentration in solution and is dependent on both the type of metal as well as the temperature at which the CTF was synthesized. Evidence for site specific metal coordination bodes well for the use of metal loaded CTFs as heterogeneous catalysts carrying homogeneous type active sites.

The first rhodium catalyzed arylation of imines proceeding via C-H bond functionalization is reported. Use of a non-coordinating halide abstractor is important to obtain reactivity. Aryl branched N-Boc-amines are formed and a wide range of functionality is compatible with the reaction.In the area of C-H bond functionalization, arylation of alkenes and alkynes have been well explored. 1 In contrast, analogous additions across C-O 2 or C-N 3-5 multiple bonds are rare. Due to the prevalence of α-branched amines in drugs and natural products, 6 we sought a method for the arylation of imines via C-H bond functionalization. The most closely related transformations are Pd-catalyzed additions to N-tosyl imines that rely on the functionalization of acidic C-H bonds. 5 Herein, we report the high-yielding 2-pyridyldirected arylation of a wide range of aromatic N-Boc-imines with a Rh(III) catalyst.Our investigations focused on additions to N-Boc-imines due to the convenience and ease of removal of the exceedingly popular Boc protecting group. As the test substrate for arylation, we chose 2-phenylpyridine (1a) because of the pyridyl directing group's high chemical stability and rich history in C-H functionalization with a variety of transition metals. 1d,e, 7We began our reaction exploration with Rh(III) catalysts. This type of catalyst has been proposed to activate C-H bonds via an electrophilic deprotonation mechanism to generate an aryl-Rh(III) species. 8 However, upon heating 10 mol % [Cp*RhCl 2 ] 2 (Cp*: pentamethyl cyclopentadienyl) with 2-phenylpyridine and N-Boc-benzaldimine in CH 2 Cl 2 , no product was observed (entry 1, Table 1). Theorizing that the lack of reactivity may be due to the chloride ligands on the metal, which could prevent coordination of the N-Boc-imine, AgSbF 6 was added as a halide abstractor and provided the desired product (3a) in 55% yield (entry 2). 9 Utilizing coordinating solvents such as THF (entry 3) and DMF (entry 4) resulted in lower activity while solvents such as benzene failed due to insolubility of the catalyst system (entry 5). Analogous iridium (entry 6) and ruthenium (entry 7) based complexes were found to be inactive for this transformation. Substrate stoichiometries were also explored (entries 8 and 9) with the highest yield being achieved by employing two equivalents of the least expensive component, 2-phenylpyridine (entry 9). Under these conditions, the excess 2-phenylpyridine is recovered. Unreacted N-Boc imine is not

Liquid injection field desorption/ionization (LIFDI) has been applied to identify transition metal complexes that are highly reactive to air and moisture by mass spectrometry. The complexes of nickel and rhodium were supplied as dilute solutions (approximately 0.2 mg ml(-1)) in toluene, tetrahydrofuran or acetonitrile, and were applied onto the field desorption emitter inside the vacuum of the ion source under inert conditions by means of the injection capillary unique to the LIFDI set-up. LIFDI mass spectrometry on a double-focusing magnetic sector instrument provided spectra exhibiting intense molecular ion peaks for the species investigated or signals that could easily be related to the target compound by assuming neutral loss of the weakest-bound ligand. Eventually, byproducts of the synthesis or other components resulting from incomplete reactions or some degree of decomposition were also detected.

Rh(III)-catalyzed arylation of imines provides a new method for C–C bond formation, while simultaneously introducing an α-branched amine as a functional group. A detailed mechanistic study provides insights for the rational future development of this new reaction. Relevant intermediate Rh(III)-complexes have been isolated, characterized, and their reactivity in stoichiometric reactions with relevant substrates have been monitored. The reaction was found to be first order in the catalyst resting state and inverse first order in the C-H activation substrate.

Synthetic access to the zerovalent palladium complexes {[(o-Ph 2 PC 6 H 4 ) 2 BPh]Pd(L)} (L = pyridine (8a), 2,6-lutidine (8b)) is reported. Structural characterization and DFT analysis of 8a revealed a strong Pd→B interaction, which appears to inhibit oxidative addition reactions. Activation of allyl acetate is possible by reversible transfer of the acetate leaving group to the ligand's borane functionality. Catalytic activity in the allylic substitution of allyl acetate with HNEt 2 is sensitive to the presence of free acetate, which reduces borane inhibition by reversible borate formation.