The Still Elusive Role of Lightweight Doping in Carbon-Based Electrocatalysts for the Selective Oxygen Reduction Reaction to Hydrogen Peroxide.

The two-electron electrocatalytic oxygen reduction reaction (ORR) to hydrogen peroxide (HO) is a valuable alternative to the more conventional and energy-intensive anthraquinone process. From a circularity viewpoint, metal-free catalysts constitute a sustainable alternative for the process. In particular, lightweight hetero-doped C-materials are cost-effective and easily scalable samples that replace - more and more frequently - the use of critical raw elements in the preparation of highly performing (electro)catalysts.

Catalysis for Carbon-Circularity: Emerging Concepts and Role of Inorganic Chemistry.

Carbon circularity is crucial for achieving a circular economy but has wider implications and impacts with respect to the circularity of materials. It has an in-depth transformative effect on the economy. CO recycling is a critical component for this objective, with catalysis and inorganic chemistry playing a determining role in achieving this challenge.

Understanding the complexity in bridging thermal and electrocatalytic methanation of CO.

The selective methanation of CO is an important research area to meet the net-zero emission targets. Furthermore, it is crucial to develop solutions to achieve carbon neutrality, hydrogen utilization, carbon circularity, and chemical-energy storage. This conversion can be realized the thermocatalytic multistep power-to-X route or by direct electro- (or photoelectro)-catalytic technologies.

Across the Board: Gabriele Centi on Decoupling Electrocatalytic Reactions to Electrify Chemical Production.

In this series of articles, the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. This entry features Prof. G.

Bis[2,3-bis-(pyridin-2-yl)pyrazine-κ , ]palladium(II) dinitrate aceto-nitrile monosolvate.

The title compound, [Pd(CHN)](NO)·CHCN, consists of a cationic Pd complex, two anions and one lattice solvent mol-ecule, all in general positions. In the complex, the Pd cation is four-coordinated in a slightly distorted square-planar geometry defined by the four N atoms of two bidentate 2,3-di-2-pyridyl-pyrazine ligands. The complex, anions and solvent mol-ecule are linked by weak C-H⋯O inter-molecular hydrogen bonds.

Di-chlorido-(pyridine-κ)[2,3,5,6-tetra-kis-(pyridin-2-yl)pyrazine-κ , , ]nickel(II).

In the title complex, [NiCl(CHN)(CHN)], the Ni ion is six-coordinated in a distorted octa-hedral coordination environment defined by three N atoms of the tridentate 2,3,5,6-tetra-2-pyridyl-pyrazine ligand, one N atom of the pyridine ligand and two Cl anions, with the latter being mutually . The complex is disposed about a twofold rotation axis along the axis. The complex molecules are connected in the crystal C-H⋯Cl, C-H⋯N and π-π [closest inter-centroid separation = 3.

Di-μ-chlorido-bis-{chlorido-[2,4,6-tris-(pyridin-2-yl)-1,3,5-triazine-κ , , ]nickel(II)}.

In the title compound, [NiCl(CHN)], the Ni ions are hexa-coordinated in a distorted octa-hedral coordination environment defined by three N atoms of the tridentate 2,4,6-tri-2-pyridyl-1,3,5-triazine ligand and three Cl anions in a meridional geometry. The two Ni ions are bridged by two Cl anionic ligands, thereby forming a dinuclear complex. A crystallographic centre of inversion is located at the centroid of the NiCl ring.

-Poly[[(2,2'-bi-pyridine-κ ,')manganese(II)]-di-μ-bromido].

In the polymeric title complex, [MnBr(CHN)] , the Mn ion, situated on a twofold axis of symmetry, is six-coordinated in a distorted octa-hedral coordination geometry defined by two N atoms from the chelating 2,2'-bi-pyridine ligand and four bridging Br anions. The crystal reveals a one-dimensional Br-bridged chain along the axis direction with a zigzag topology. In the crystals, contacts between chains include π-π inter-actions between pyridyl rings [inter-centroid separation = 4.

(Nitrato-κ)(2,2':6',2''-terpyridine-κ ,','')palladium(II) nitrate.

The title complex, [Pd(NO)(CHN)]NO, comprises a cationic Pd complex and a nitrate anion. In the complex, the Pd cation is four-coordinated in a distorted square-planar coordination geometry defined by the three N atoms of the tridentate 2,2':6',2''-terpyridine ligand and one O atom from the NO anion. In the crystal, the complex mol-ecules are stacked in columns along the axis being connected by π-π stacking [closest inter-centroid separation between pyridyl rings = 3.

{4,4'-Di-bromo-2,2'-[cyclo-hexane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-κ ,,','}nickel(II).

In the title compound, [Ni(CHBrNO)], the Ni ion is four-coordinated in a slightly distorted square-planar coordination geometry defined by two N atoms and two O atoms of the tetra-dentate dianionic 4,4'-di-bromo-2,2'-[cyclo-hexane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato ligand. Pairs of complex mol-ecules are assembled by inter-molecular C-H⋯O hydrogen bonds with (C⋯O) = 3.247 (4) Å.

CO2 utilization: an enabling element to move to a resource- and energy-efficient chemical and fuel production.

CO(2) conversion will be at the core of the future of low-carbon chemical and energy industry. This review gives a glimpse into the possibilities in this field by discussing (i) CO(2) circular economy and its impact on the chemical and energy value chain, (ii) the role of CO(2) in a future scenario of chemical industry, (iii) new routes for CO(2) utilization, including emerging biotechnology routes, (iv) the technology roadmap for CO(2) chemical utilization, (v) the introduction of renewable energy in the chemical production chain through CO(2) utilization, and (vi) CO(2) as a suitable C-source to move to a low-carbon chemical industry, discussing in particular syngas and light olefin production from CO(2). There are thus many stimulating possibilities offered by using CO(2) and this review shows this new perspective on CO(2) at the industrial, societal and scientific levels.

[1,4-Bis(di-phenyl-phosphan-yl)butane-κ(2) P,P']di-bromido-palladium(II).

In the title complex, [PdBr2(C28H28P2)], the Pd(II) ion has a distorted cis-Br2P2 square-planar coordination geometry defined by two P atoms from the chelating 1,4-bis-(di-phenyl-phosphan-yl)butane ligand and two Br(-) anions. The four phenyl rings are inclined to the least-squares plane of the PdBr2P2 unit [maximum deviation = 0.1294 (7) Å], making dihedral angles of 66.

Catalysis for biomass and CO2 use through solar energy: opening new scenarios for a sustainable and low-carbon chemical production.

The use of biomass, bio-waste and CO2 derived raw materials, the latter synthesized using H2 produced using renewable energy sources, opens new scenarios to develop a sustainable and low carbon chemical production, particularly in regions such as Europe lacking in other resources. This tutorial review discusses first this new scenario with the aim to point out, between the different possible options, those more relevant to enable this new future scenario for the chemical production, commenting in particular the different drivers (economic, technological and strategic, environmental and sustainability and socio-political) which guide the selection. The case of the use of non-fossil fuel based raw materials for the sustainable production of light olefins is discussed in more detail, but the production of other olefins and polyolefins, of drop-in intermediates and other platform molecules are also analysed.

cis-Dibromidobis(2-phenyl-pyridine-κN)platinum(II).

In the title complex, [PtBr(2)(C(11)H(9)N)(2)], the Pt(II) ion has a distorted cis-Br(2)N(2) square-planar coordination geometry defined by two N atoms from two 2-phenyl-pyridine (ppy) ligands and two Br(-) anions. The ppy ligands are not planar, the dihedral angles between the pyridine and benzene rings being 49.0 (3) and 47.

Bis(di-2-pyridyl-amine-κ(2)N(2),N(2'))palladium(II) bis-(thio-cyanate).

The Pd(II) atom of the title salt, [Pd(C(10)H(9)N(3))(2)](NCS)(2), lies on a center of inversion and exists in a square-planar environment defined by the four pyridine N atoms derived from the two chelating di-2-pyridyl-amine (dpa) ligands. The chelate ring displays a boat conformation with a dihedral angle between the pyridine rings of 43.0 (1)°.

(Di-2-pyridyl-amine-κ(2)N(2),N(2'))diiodidopalladium(II).

The Pd(II) ion in the title complex, [PdI(2)(C(10)H(9)N(3))], is four-coordinated in a distorted square-planar environment defined by the two pyridine N atoms of the chelating di-2-pyridyl-amine (dpa) ligand and two I(-) anions. The dpa ligand is not planar, the dihedral angle between the pyridine rings being 51.2 (2)°.

Tetra-bromido(di-2-pyridyl-amine-κ(2)N(2),N(2'))platinum(IV).

The Pt(IV) ion in the title complex, [PtBr(4)(C(10)H(9)N(3))], is six-coordinated in a slightly distorted octa-hedral environment by two pyridine N atoms from a chelating di-2-pyridyl-amine (dpa) ligand and four Br(-) anions. The complex mol-ecule has mirror symmetry, with the Pt(IV) atom, two Br atoms and the central N atom of the dpa ligand lying on the mirror plane. The dpa ligand is not planar, showing a dihedral angle of 34.

(2,2'-Bipyrimidine-κ(2)N(1),N(1'))diiodidopalladium(II).

In the title complex, [PdI(2)(C(8)H(6)N(4))], the Pd(II) ion is four-coordinated in a slightly distorted square-planar environment defined by two pyrimidine N atoms derived from a chelating 2,2'-bipyrimidine (bpym) ligand and two mutually cis iodide anions. The nearly planar bpym ligand [maximum deviation = 0.053 (3) Å] is slightly inclined to the least-squares plane of the PdI(2)N(2) unit [maximum deviation = 0.

2-Eth-oxy-6-{[1-(3-eth-oxy-2-hy-droxy-benz-yl)-1H-benzimidazol-2-yl]meth-yl}phenol nitro-methane monosolvate.

In the title solvate, C(24)H(24)N(2)O(4)·CH(3)NO(2), the benzene ring of the 2-eth-oxy-6-methyl-phenol substituent is approximately perpendicular to the nearly planar benzimidazole ring [maximum deviation = 0.021 (2) Å], making a dihedral angle of 84.32 (7)°.

(2,3-Di-2-pyridyl-pyrazine-κ(2)N(2),N(3))diiodidoplatinum(II).

The Pt(II) ion in the title complex, [PtI(2)(C(14)H(10)N(4))], exists in a distorted square-planar environment defined by the two pyridine N atoms of the chelating 2,3-di-2-pyridyl-pyrazine ligand and two iodide anions. The pyridine rings are inclined to the least-squares plane of the PtI(2)N(2) unit [maximum deviation = 0.070 (3) Å] at 66.

4-Nitro-2-{[(tricyclo-[3.3.1.1(3,7)]decan-1-yl)iminium-yl]meth-yl}phenolate.

The title compound, C(17)H(20)N(2)O(3), is a Schiff base, which is found as a zwitterion in the solid state. The geometry around the iminium N atom indicates sp(2)-hybridization. The zwitterion shows a strong intra-molecular N-H⋯O hydrogen-bond inter-action between the iminium N atom and the phenolate O atom.

A monoclinic polymorph of (R,R)-4,4'-dibromo-2,2'-[cyclo-hexane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenol.

The title compound, C(20)H(20)Br(2)N(2)O(2), a tetra-dentate Schiff base, is the enanti-omerically pure R,R-diastereomer of four possible stereoisomers. The mol-ecular structure reveals two strong intra-molecular O-H⋯N hydrogen bonds between the hy-droxy O atom and the imino N atom, which each generate S(6) rings. In the crystal, mol-ecules are stacked in columns along the a axis; when viewed down the b axis, successive columns are stacked in the opposite direction.

4,4'-Dinitro-2,2'-[propane-1,3-diylbis(iminiumylmethanylyl-idene)]diphenolate.

The title compound, C(17)H(16)N(4)O(6), is a Schiff base, which is found as a bis-zwitterion in the solid state. The geometry around the iminium N atom indicates sp(2)-hybridization. The diiminiumpropyl-ene chain is in an approximate double-gauche conformation, with average N-C-C-C torsion angles of 69.

2-Eth-oxy-6-[1-(3-eth-oxy-2-hy-droxy-benz-yl)-2,3-dihydro-1H-benzimidazol-2-yl]phenol acetonitrile monosolvate.

The title compound, C(24)H(24)N(2)O(4)·CH(3)CN, a disubstituted benzimidazole, crystallized as an acetonitrile monosolvate. The benzene ring of the 2-eth-oxy-6-methyl-phenol substiuent is approximately perpendicular to the nearly planar benzimidazole ring system [maximum deviation = 0.016 (1) Å], making a dihedral angle of 84.

(2,2'-Bipyrimidine-κ(2)N(1),N(1'))bis-(thio-cyanato-κN)platinum(II).

In the title complex, [Pt(NCS)(2)(C(8)H(6)N(4))], the Pt(II) ion is four-coordinated in a distorted square-planar environment defined by two pyrimidine N atoms derived from a chelating 2,2'-bipyrimidine (bpym) ligand and two mutually cis N atoms from two SCN(-) anions. The thio-cyanate ligands are almost linear, displaying N-C-S bond angles of 178.6 (11) and 173.