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Platinum(II) metalla‐N‐heterocyclic carbene complexes featuring pyridyl heterocyclic moiety demonstrate remarkable catalytic efficiency in alkyne hydrosilylation under green light irradiation. The photocatalytic properties of complexes are rationalised by the photo‐induced charge transfer occurring in extended condensed system identified with the help of various experimental (UV/vis and emission spectroscopy, cyclic voltammetry) and theoretical methods (DFT/TD‐DFT, IFCT analysis). [ABSTRACT FROM AUTHOR]

A series of platinum complexes featuring phosphine and isocyanide ligands [PtX2(PPh3)(CNCy)] (X = Cl, Br, and I) as well as their parent phosphine [PtX2(PPh3)2] and isocyanide [PtX2(CNCy)2] analogues have been prepared and evaluated as catalysts for the photocatalytic hydrosilylation of alkynes. Under violet light irradiation (λmax = 400 nm), phosphine–isocyanides complexes [PtX2(PPh3)(CNCy)] gave high yields of silylated products (product yield up to 99%, TONs up to 1.98 × 103). The blue light irradiation (λmax = 450 nm) was more suitable for the parent phosphine complexes [PtX2(PPh3)2], which showed comparable efficiency (product yield up to 99%, TON up to 1.98 × 103), while isocyanide complexes [PtX2(CNCy)2] were not active. [ABSTRACT FROM AUTHOR]

Palladium(II) and platinum(II) complexes featuring metalla-N-heterocyclic carbenes (7–12) were synthesised via metal-mediated coupling between equimolar cis-[MCl2(CNR)2] (R = 2,6-Me2C6H3 (Xyl), 2,4,6-Me3C6H3 (Mes)) and 2-aminopyridine or 2-aminopyrazine. Thiocyanate complexes 13–18 with two thiocyanate ligands were obtained through the ligand exchange in the parent compounds 7–12 with NH4CNS in acetone/CH2Cl2. Complexes 7–18 were isolated and characterised by HRESI+-MS, IR, 1H and 13C{1H} NMR spectroscopy and single-crystal X-ray diffraction (in the case of 11, 16, and 18). The UV-vis properties of 7–18 and the electrochemical properties of 7–12 were also evaluated. To study the electronic structure and bonding nature in the new compounds, the quantum theory of atoms in molecules (QTAIM) and Mayer bond order analysis together with the extended transition state with the natural orbitals for chemical valence (ETS-NOCV) method, were used. X-ray diffraction studies and theoretical considerations indicate that the thiocyanate derivatives 16 and 18 form supramolecular dimers by two symmetrical pairs M1⋯C5 and S1⋯C2 with short intermolecular contacts between an electron-rich MII-center and thiocyanate ligand on the one side and the electron-poor π-system of an azaheterocyclic ring on the other side. Representative carbenes 8, 11 and 12 were evaluated as photocatalysts for the hydrosilylation of diphenylacetylene with triethylsilane giving 1,2-(diphenylvinyl)triethylsilane in 98% yield under visible light irradiation (blue light, 445 nm). [ABSTRACT FROM AUTHOR]

Endo‐β‐xylanases are hemicellulases involved in the conversion of xylans in plant biomass. Here, we report a novel acidophilic β‐xylanase (ScXynA) with high transglycosylation abilities that was isolated from the filamentous fungus Scytalidium candidum 3C. ScXynA was identified as a glycoside hydrolase family 10 (GH10) dimeric protein, with a molecular weight of 38 ± 5 kDa per subunit. The enzyme catalyzed the hydrolysis of different xylans under acidic conditions and was stable in the pH range 2.6–4.5. The kinetic parameters of ScXynA were determined in hydrolysis reactions with p‐nitrophenyl‐β‐d‐cellobioside (pNP‐β‐Cel) and p‐nitrophenyl‐β‐d‐xylobioside (pNP‐β‐Xyl2), and kcat/Km was found to be 0.43 ± 0.02 (s·mM)−1 and 57 ± 3 (s·mM)−1, respectively. In the catalysis of the transglycosylation o‐nitrophenyl‐β‐d‐xylobioside (oNP‐β‐Xyl2) acted both as a donor and an acceptor, resulting in the efficient production of o‐nitrophenyl xylooligosaccharides, with a degree of polymerization of 3–10 and o‐nitrophenyl‐β‐d‐xylotetraose (oNP‐β‐Xyl4) as the major product (18.5% yield). The modeled ScXynA structure showed a favorable position for ligand entry and o‐nitrophenyl group accommodation in the relatively open −3 subsite, while the cleavage site was covered with an extended loop. These structural features provide favorable conditions for transglycosylation with oNP‐β‐Xyl2. The acidophilic properties and high transglycosylation activity make ScXynA a suitable choice for various biotechnological applications, including the synthesis of valuable xylooligosaccharides. [ABSTRACT FROM AUTHOR]

The dihalomethanes CH2X2 (X=Cl, Br, I) were co‐crystallized with the isocyanide complexes trans‐[MXM2(CNC6H4‐4‐XC)2] (M=Pd, Pt; XM=Br, I; XC=F, Cl, Br) to give an extended series comprising 15 X‐ray structures of isostructural adducts featuring 1D metal‐involving hexagon‐like arrays. In these structures, CH2X2 behave as bent bifunctional XB/XB‐donating building blocks, whereas trans‐[MXM2(CNC6H4‐4‐XC)2] act as a linear XB/XB acceptors. Results of DFT calculations indicate that all XCH2–X⋅⋅⋅XM–M contacts are typical noncovalent interactions with estimated strengths in the range of 1.3–3.2 kcal mol−1. A CCDC search reveals that hexagon‐like arrays are rather common but previously overlooked structural motives for adducts of trans‐bis(halide) complexes and halomethanes. [ABSTRACT FROM AUTHOR]

The isocyanide complexes cis-[MCl2(CNC6H4-4-X)2] (M = Pd; X = Cl, Br; M = Pt; X = Br) form isomorphous crystal structures exhibiting the Cl/Br and Pd/Pt exchanges featuring 1D chains upon crystallisation. Crystal packing is supported by the C–X···X–C halogen bonds (HaBs), C–H···X–C hydrogen bonds (HB), X···M semicoordination, and C···C contacts between the C atoms of aryl isocyanide ligands. The results of DFT calculations and topological analysis indicate that all the above contact types belong to attractive noncovalent interactions. A projection of the electron localization function (ELF) and an inspection of the electron density (ED) and the electrostatic potential (ESP) reveal the amphiphilic nature of X atoms playing the role of HaB donors, HaB and HB acceptors, and a nucleophilic partner in X···M semicoordination. [ABSTRACT FROM AUTHOR]