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A recent broadband rotational spectroscopic investigation of the cross-association mechanisms of CO2 with monoethanolamine (MEA) in molecular beams [F. Xie et al., Angew. Chem. Int. Ed., 2023, 62, e202218539] revealed an intriguing affinity of CO2 to the hydroxy group. These findings have triggered the present systematic vibrational spectroscopic exploration of weakly bound amine··CO2 and alcohol··CO2 van der Waals cluster molecules embedded in inert "quantum" matrices of neon at 4.2 K complemented by high-level quantum chemical conformational analyses. The non-covalent interactions formed between the amino and hydroxy groups and the electron-deficient carbon atom of CO2 are demonstrated to lift the degeneracy of the doubly degenerate intramolecular CO2-bending fundamental significantly with characteristic observed spectral splittings for the amine··CO2 (≈35–45 cm−1) and alcohol··CO2 (≈20–25 cm−1) interactions, respectively, despite the almost identically predicted total association energies (≈12–14 kJ·mol−1) for these van der Waals contacts, as revealed by benchmark Domain-based Local Pair Natural Orbital Coupled Cluster DLPNO-CCSD(T) theory. These high-level theoretical predictions reveal significantly higher "geometry preparation energies" for the amine··CO2 systems leading to a more severe distortion of the CO2 linearity upon complexation in agreement with the infrared spectroscopic findings. The systematic combined spectroscopic and quantum chemical evidences for cross-association between CO2 and amines/alcohols in the present work unambiguously confirm an intriguing binding preference of CO2 to the hydroxy group of the important carbon capture agent MEA, with an accurate vibrational zero-point energy corrected association energy (D0) of 13.5 kJ·mol−1 at the benchmark DLPNO-CCSD(T)/aug-cc-pV5Z level of theory. [ABSTRACT FROM AUTHOR]

The self-association mechanisms of phenol have represented long-standing challenges to quantum chemical methodologies owing to the competition between strongly directional intermolecular hydrogen bonding, weaker non-directional London dispersion forces and C–H· · · π interactions between the aromatic rings. The present work explores these subtle self-association mechanisms of relevance for biological molecular recognition processes via spectroscopic observations of large-amplitude hydrogen bond librational modes of phenol cluster molecules embedded in inert neon “quantum” matrices complemented by domain-based local pair natural orbital-coupled cluster DLPNO-CCSD(T) theory. The spectral signatures confirm a primarily intermolecular O-H· · · H hydrogen-bonded structure of the phenol dimer strengthened further by cooperative contributions from inter-ring London dispersion forces as supported by DLPNO-based local energy decomposition (LED) predictions. In the same way, the hydrogen bond librational bands observed for the trimeric cluster molecule confirm a pseudo-C3 symmetric cyclic cooperative hydrogen-bonded barrel-like potential energy minimum structure. This structure is vastly different from the sterically favored “chair” conformations observed for aliphatic alcohol cluster molecules of the same size owing to the additional stabilizing London dispersion forces and C–H· · · π interactions between the aromatic rings. The hydrogen bond librational transition observed for the phenol monohydrate finally confirms that phenol acts as a hydrogen bond donor to water in contrast to the hydrogen bond acceptor role observed for aliphatic alcohols. [ABSTRACT FROM AUTHOR]

The base‐free transfer hydrogenation of biomass derived furanic aldehydes with ruthenium and iridium pincer complexes was studied using bio‐alcohols as the hydrogen source. The furanic substrates, such as 5‐hydroxymethyl furfural (HMF) and thiophene‐2‐carboxaldehyde (TC), were reduced under mild conditions (35–80 °C) affording the desired alcohols with excellent conversions and yields. It was also possible to extend this methodology for the transfer hydrogenation of 5‐formylfurfural (DFF) at 130 °C. Deuterium labelling of C−H functions in the furanic alcohols was also investigated in the presence of ethanol‐d6. Finally, proposed catalytic resting species derived from the interactions between one of the catalysts and furanic reagents/product as well as the solvent during the transfer hydrogenation (TH) reaction were analysed. [ABSTRACT FROM AUTHOR]

We report the synthesis of pyrazine-pillared metal–organic frameworks (MOFs) generated through ligand substitution of the Group 6 metal hexacarbonyls. The obtained frameworks exhibit hexagonal pore channels with CO-plastered porewalls. This series constitutes the first crystallographically characterized examples of Cr(0), Mo(0), and W(0)-based MOFs and suggests the exploration of homoleptic metal carbonyls as starting materials to generate polymeric materials with low-valent metal nodes. [ABSTRACT FROM AUTHOR]

We report the synthesis of pyrazine-pillared metal–organic frameworks (MOFs) generated through ligand substitution of the Group 6 metal hexacarbonyls. The obtained frameworks exhibit hexagonal pore channels with CO-plastered porewalls. This series constitutes the first crystallographically characterized examples of Cr(0), Mo(0), and W(0)-based MOFs and suggests the exploration of homoleptic metal carbonyls as starting materials to generate polymeric materials with low-valent metal nodes. [ABSTRACT FROM AUTHOR]

Keywords: bioalcohols; furanics; green chemistry; transfer hydrogenation EN bioalcohols furanics green chemistry transfer hydrogenation 1 1 1 01/27/23 20230120 NES 230120 B The Front Cover b shows the schematic diagram of converting bio-based furanic alcohols using transfer hydrogentaion. Front Cover: Catalytic Base-Free Transfer Hydrogenation of Biomass Derived Furanic Aldehydes with Bioalcohols and PNP Pincer Complexes (ChemCatChem 2/2023) In their Research Article, R. Padilla, M. Nielsen and co-workers disclose the catalytic performance of different pincer complexes for the base-free transfer hydrogenation (TH) of bio-based furanic aldehydes in presence of EtOH, iPrOH or MeOH as hydrogen sources and solvents under mild reaction conditions. [Extracted from the article]

A combined microwave, infrared, and computational investigation of CHBrF(2) is reported. For the vibrational ground state, measurements in the millimeter- and sub-millimeter-wave regions for CH(79)BrF(2) and CH(81)BrF(2) provided rotational and centrifugal-distortion constants up to the sextic terms as well as the hyperfine parameters (quadrupole-coupling and spin-rotation interaction constants) of the bromine nucleus. The determination of the latter was made possible by recording of spectra at sub-Doppler resolution, achieved by means of the Lamb-dip technique, and supporting the spectra analysis by high-level quantum chemical calculations at the coupled-cluster level. In this context, the importance of relativistic effects, which are of the order of 6.5% and included in the present work using second-order direct perturbation theory, needs to be emphasized for accurate predictions of the bromine quadrupole-coupling constants. The infrared measurements focused on the ν(4) fundamental band of CH(79)BrF(2). Fourier transform investigations using a synchrotron radiation source provided the necessary resolution for the observation and analysis of the rotational structure. The spectroscopic parameters of the v(4) = 1 state were found to be close to those of the vibrational ground state, indicating that the ν(4) band is essentially unaffected by perturbations.