Green-Light Hydrosilylation Photocatalysis with Platinum(II)Metalla-N-Heterocyclic Carbene Complexes.

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).

Conformation-Associated C···-Pt Tetrel Bonding: The Case of Cyclometallated Platinum(II) Complex with 4-Cyanopyridyl Urea Ligand.

The nucleophilic addition of 3-(4-cyanopyridin-2-yl)-1,1-dimethylurea () to -[Pt(CNXyl)Cl] () gave a new cyclometallated compound . It was characterized by NMR spectroscopy (H, C, Pt) and high-resolution mass spectrometry, as well as crystallized to obtain two crystalline forms ( and ·2MeCN), whose structures were determined by X-ray diffraction. In the crystalline structure of , two conformers ( and ) were identified, while the structure ·2MeCN had only one conformer .

Halogen Bonding Involving Isomeric Isocyanide/Nitrile Groups.

2,3,5,6-Tetramethyl-1,4-diisocyanobenzene (), 1,4-diisocyanobenzene (), and 1,4-dicyanobenzene () were co-crystallized with 1,3,5-triiodotrifluorobenzene (1,3,5-FIB) to give three cocrystals, ·1,3,5-FIB, ·2(1,3,5-FIB), and ·2(1,3,5-FIB), which were studied by X-ray diffraction. A common feature of the three structures is the presence of I···C or I···N halogen bonds (HaBs), which occurs between an iodine σ-hole and the isocyanide C-(or the nitrile N-) atom. The diisocyanide and dinitrile cocrystals ·2(1,3,5-FIB) and ·2(1,3,5-FIB) are isostructural, thus providing a basis for accurate comparison of the two types of noncovalent linkages of C≡N/N≡C groups in the composition of structurally similar entities and in one crystal environment.

Incorporation of a Fluorine Atom in a Bridging Ligand of Half-Lantern Pt Complexes Provides up to 10-Fold Enhancement of Electroluminescence Brightness.

The binuclear half-lantern platinum(II) complexes [Pt(pbt)(μ-SN)] (pbtH = 2-phenylbenzothiazole, SN = benzo[]thiazole-2-thiolate , 6-fluorobenzo[]thiazole-2-thiolate , 6-chlorobenzo[]thiazole-2-thiolate , 6-bromobenzo[]thiazole-2-thiolate , and 6-iodobenzo[]thiazole-2-thiolate ) were synthesized by the treatment of the in situ formed [Pt(pbt)(NCMe)]NO complex and appropriate benzo[]thiazole-2-thiole in the presence of BuOK; yield: 51-84%. Complexes - exhibit intense red photoluminescence originated from MMLCT state reaching 22% room temperature quantum yields in a CHCl solution. All complexes display excited-state decay kinetics both in solution and in the solid state; the kinetics was adequately modeled by single exponentials.

Photo- and Electroluminescent Neutral Iridium(III) Complexes Bearing Imidoylamidinate Ligands.

Imidoylamidinate-based heteroleptic bis(2-phenylbenzothiazole)iridium(III) and -rhodium(III) complexes [()M(NN)] ( = 2-phenylbenzothiazole, NN = '-(benzo[]thiazol-2-yl)acetimidamidyl ( and ), '-(6-fluorobenzo[]thiazol-2-yl)acetimidamidyl (), '-(benzo[]oxazol-2-yl)acetimidamidyl (), '-(1-methyl-1-benzo[]imidazol-2-yl)acetimidamidyl (); yields 70-84%) were obtained by the reaction of the in situ-generated solvento-complex [()M(NCMe)]NO and benzo[]thia/oxa/-methylimidozol-2-amines in the presence of NaOMe. Complexes - exhibited intense orange photoluminescence, reaching 37% at room temperature quantum yields, being immobilized in a poly(methyl methacrylate) matrix. A photophysical study of these species in a CHCl solution, neat powder, and frozen (77 K) MeOCHOH-EtOH glass matrix─along with density-functional theory (DFT), ab initio methods, and spin-orbit coupling time-dependent DFT calculations─verified the effects of substitution in the imidoylamidinate ligands on the excited-state properties.

Experimental and computational tuning of metalla-N-heterocyclic carbenes at palladium(II) and platinum(II) centers.

Palladium(II) and platinum(II) complexes featuring metalla-N-heterocyclic carbenes (7-12) were synthesised metal-mediated coupling between equimolar -[MCl(CNR)] (R = 2,6-MeCH (Xyl), 2,4,6-MeCH (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 NHCNS in acetone/CHCl. Complexes 7-18 were isolated and characterised by HRESI-MS, IR, H and C{H} NMR spectroscopy and single-crystal X-ray diffraction (in the case of 11, 16, and 18).

Metal-Involving Chalcogen Bond. The Case of Platinum(II) Interaction with Se/Te-Based σ-Hole Donors.

Platinum(II) complexes exhibiting an expressed -nucleophilicity of the positively charged metal centers, namely, [Pt(ppy)(acac)] (; acacH is acetylacetone; ppyH is 2-Ph-pyridine) and [Pt(ppy)(tmhd)] (; tmhdH is 2,2,6,6-tetramethylheptanedione-3,5), were cocrystallized with the chalcogen bond donors (4-NCF)Ch (Ch = Se, Te) to form two isostructural cocrystals ·/(4-NCF)Ch, and ·/(4-NCF)Se and ·(4-NCF)Te. The X-ray data for these cocrystals and appropriate theoretical DFT calculations (PBE0-D3BJ) allowed the recognition of the metal-involving chalcogen bond, namely, Ch···-Pt (its energy spans from -7 to -12 kcal/mol). In ·/(4-NCF)Ch, Ch···-Pt bonding is accompanied by the C···-Pt interaction, representing a three-center bifurcate, whereas in ·(4-NCF)Te the chalcogen bond Te···-Pt is purely two-centered and is stronger than that in ·/(4-NCF)Ch because of more efficient orbital overlap.

Comparative Structural Study of Three Tetrahalophthalic Anhydrides: Recognition of X···O(anhydride) Halogen Bond and πh···O(anhydride) Interaction.

Structures of three tetrahalophthalic anhydrides (TXPA: halogen = Cl (TCPA), Br (TBPA), I (TIPA)) were studied by X-ray diffraction, and several types of halogen bonds (HaB) and lone pair···π-hole (lp···πh) contacts were revealed in their structures. HaBs involving the central oxygen atom of anhydride group (further X···O(anhydride) were recognized in the structures of TCPA and TBPA. In contrast, for the O(anhydride) atom of TIPA, only interactions with the π system (π-hole) of the anhydride ring (further lp(O)···πh) were observed.

Supramolecular Assembly of Metal Complexes by (Aryl)I⋅⋅⋅d [Pt ] Halogen Bonds.

The theoretical data for the half-lantern complexes [{Pt( )(μ- )} ] [1-3; is cyclometalated 2-Ph-benzothiazole; is 2-SH-pyridine (1), 2-SH-benzoxazole (2), 2-SH-tetrafluorobenzothiazole (3)] indicate that the Pt⋅⋅⋅Pt orbital interaction increases the nucleophilicity of the outer d orbitals to provide assembly with electrophilic species. Complexes 1-3 were co-crystallized with bifunctional halogen bonding (XB) donors to give adducts (1-3) ⋅(1,4-diiodotetrafluorobenzene) and infinite polymeric [1⋅1,1'-diiodoperfluorodiphenyl] . X-ray crystallography revealed that the supramolecular assembly is achieved through (Aryl)I⋅⋅⋅d [Pt ] XBs between iodine σ-holes and lone pairs of the positively charged (Pt ) centers acting as nucleophilic sites.