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Structural knowledge on ubiquitous lithium salts in solution and in the crystalline state is of paramount importance for our understanding of many chemical reactions and of the electrolyte behaviour in lithium ion batteries. A bulky bidentate Si-based ligand (6) was used to create simplified model systems suitable for correlating structures of LiCl and LiPF6 complexes in the solid-state and in solution by combining various experimental, spectroscopic, and computational methods. Solution studies were performed using 1H DOSY, multinuclear variable temperature NMR spectroscopy, and quantum chemical calculations. [Ph2Si(2-CH2Py)2·LiCl]2 (3) dissociates into a monomeric species (9) in THF. For [Ph2Si(2-CH2Py)2·LiPF6]2 (11), low temperature NMR studies revealed an unprecedented chiral coordination mode (12) in non-coordinating solvents.

We report here the activation of CO2 using two Mn-PNN pincer complexes that can exhibit different modes of metal–ligand cooperation amido/amino mode that involves [1,2]-activation of CO2 and dearomatization/aromatization mode that involves [1,3]-activation of CO2. We also compare their catalytic activity for CO2 hydrogenation.

The first example of a homogeneous catalyst based on an earth-abundant metal for the hydrogenation of organic carbonates to methanol and alcohols is reported. Based on the mechanistic investigation, which indicates metal-ligand cooperation between the manganese center and the N-H group of the pincer ligand, we propose that the hydrogenation of organic carbonates to methanol occurs via formate and aldehyde intermediates. The reaction offers an indirect route for the conversion of CO2 to methanol, which coupled with the use of an earth abundant catalyst, makes the overall process environmentally benign and sustainable.

The first example of base-metal-catalysed synthesis of amides from the coupling of primary amines with either alcohols or esters is reported. The reactions are catalysed by a new manganese pincer complex and generate hydrogen gas as the sole byproduct, thus making the overall process atom-economical and sustainable.

The first example of base-metal-catalyzed dehydrogenative coupling of diols and amines to form cyclic imides is reported. The reaction is catalyzed by a pincer complex of the earth abundant manganese and forms hydrogen gas as the sole byproduct, making the overall process atom economical and environmentally benign.

Functionalized disiloxane units with defined structures are interesting molecular models for investigating the reactivity and chemoselectivity in transformations that are of interest in synthesis, surface chemistry, and materials science. (Mes)PhSi(OMe)(2)(1) (Mes = mesityl) and (Mes)PhSiCl2(5) were chosen as starting compounds for the controlled synthesis of methoxy-, amino-, and chloro-functionalized unsymmetric disiloxanes. Two synthesis routes towards (Mes)PhSi(OMe)(OSiPh3) (3) were followed, one via the aminomethoxysilane (Mes)PhSi(OMe)(NC4H8) (2) and the other via the chlorodisiloxane (Mes)PhSiCl(OSiPh3) (6). The amino-substituted disiloxane (Mes)PhSi(NC4H8)(OSiPh3) (4) was obtained from the chloro derivative6withN-pyrrolidinyllithium, but the same reaction starting from compound3was not successful. All provided disiloxanes were structurally characterized by X-ray crystallography.

[Image: see text] Base-metal catalyzed dehydrogenative self-coupling of 2-amino alcohols to selectively form functionalized 2,5-substituted pyrazine derivatives is presented. Also, 2-substituted quinoxaline derivatives are synthesized by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In both cases, water and hydrogen gas are formed as the sole byproducts. The reactions are catalyzed by acridine-based pincer complexes of earth-abundant manganese.

[Ru(N∧N)(MeCN)2(2-Ph-2′-Py)]PF6 (2-Ph-2′-Py = ortho-metalated 2-phenylpyridine, N∧N = phenanthroline, 2,2′-bipyridine), in which one of the nitrogens of the N∧N ligand is bound to Ru trans to the p...

Homogeneous catalytic hydrogenation of esters to alcohols is an industrially important, environmentally benign reaction. While precious metal-based catalysts for this reaction are now well known, only very few catalysts based on first-row metal complexes were reported. Here we present the hydrogenation of esters catalyzed by a complex of earth-abundant manganese. The reaction proceeds under mild conditions and insight into the mechanism is provided based on an NMR study and the synthesis of novel Mn complexes postulated as intermediates.

The catalytic dehydrogenative coupling of alcohols and amines to form aldimines represents an environmentally benign methodology in organic chemistry. This has been accomplished in recent years mainly with precious-metal-based catalysts. We present the dehydrogenative coupling of alcohols and amines to form imines and H2 that is catalyzed, for the first time, by a complex of the earth-abundant Mn. Detailed mechanistic study was carried out with the aid of NMR spectroscopy, intermediate isolation, and X-ray analysis.

The catalytic dehydrogenative coupling of alcohols and amines to form aldimines represents an environmentally benign methodology in organic chemistry. This has been accomplished in recent years mainly with precious-metal-based catalysts. We present the dehydrogenative coupling of alcohols and amines to form imines and H2 that is catalyzed, for the first time, by a complex of the earth-abundant Mn. Detailed mechanistic study was carried out with the aid of NMR spectroscopy, intermediate isolation, and X-ray analysis.

A series of heterobimetallic complexes have been prepared by π-coordination of the [CpRu]+ fragment to the aromatic ring of POCOP pincer complexes of nickel, palladium and platinum. Their molecular structures were unequivocally determined by single-crystal X-ray diffraction, exhibiting the ruthenium moiety and the POCOP aromatic ring forming sandwich like species. The analysis in the solid state and in solution clearly showed that the coordination occurs in an orthogonal fashion and, as a consequence, both faces of the pincer complexes become non equivalent, thus conferring diastereotopicity to the isopropyl substituents. The electrochemical behavior of the new bimetallic complexes was studied and compared with that of the monometallic POCOP pincer precursors.

The asymmetric unit of the title compound, [Ru(2)Br(4)(C(10)H(14))(2)], contains one half of the centrosymmetric mol-ecule. Each Ru center is coordinated by tetra-methyl-benzene ring in a η(6)-coordination mode, and one terminal and two bridging bromine atoms. The aromatic rings and the Ru(2)Br(2) four-membered ring form a dihedral angle of 55.99 (8)°. In the crystal structure, weak inter-molecular C-H⋯Br inter-actions link mol-ecules into chains propagated in [001].

Dimeric mol­ecules of the title compound, [Ru2Cl4(C12H18)2], are located on a crystallographic centre of inversion with one mol­ecule in the asymmetric unit. The hexa­methyl­benzene rings are in an η6-coordination to the ruthenium centres, which are bridged by two chloride ligands. In addition, the ruthenium centres are bonded to another chloride ligand. The aromatic rings and the Ru2Cl2 four-membered ring enclose a dihedral angle of 55.85 (6)°.

Amide synthesis is one of the most important transformations in chemistry and biology. The direct use of ammonia for the incorporation of nitrogen functionalities in organic molecules is an attractive and environmentally benign method. We present here a new synthesis of amides by acceptorless dehydrogenative coupling of benzyl alcohols and ammonia. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of a stoichiometric base, making the overall process economical, efficient, and sustainable. Interesting mechanistic insights based on detailed experimental observations, indicating the crucial role of the base, are provided.