Syntheses and Reactivity of Ruthenium σ-Pyridylacetylides

Hierarchical Synthesis, Structure, and Photophysical Properties of Gallium- and Ruthenium-Porphyrins with Axially Bonded Azo Ligands

The hierarchical synthesis of three porphyrin and four bisporphyrin derivatives is presented. This strategy relies on the incorporation of linkers based on azo moieties appended with pyridyl and/or acetylenic groups that facilitate axial coordination to Ga- and Ru-metalloporphyrins. These porphyrinic systems allow for a quantitative analysis of the effects of diamagnetic anisotropy (DA) by using ¹ H NMR spectroscopic and X-ray crystallographic analyses. A simple power-law relationship between the proton chemical shift and the distance from the porphyrin core is experimentally outlined, which confirms previous theoretical predictions and shows that the limit of DA is about 2 nm. Photophysical properties of the azo-linked porphyrins are analyzed by UV/Vis spectroscopy, showing that significant cis-trans isomerization is not observed for azo ligands bound only to Ga-porphyrins. Incorporation of Ru-porphyrins to an azo ligand facilitates photoswitching behavior, but the process faces competition from decarbonylation of the Ru-porphyrin, and appreciable switching is only documented for GaL1Ru.

Crystal structure of μ-carbonyl-1:2κ2C:C-carbonyl-1κC-(1η5-cyclo-penta-dien-yl)iodido-2κI-[μ-2-(pyridin-2-yl)ethene-1,1-diyl-1κC1:2κ2N,C1]ironpalladium(Fe-Pd) benzene monosolvate

The reaction of Cp(CO)2FeI with 2-ethynyl-pyridine under Sonogashira conditions [5% PdCl2(PPh3)2, 10% CuI, THF-NEt3 (2:1)] afforded the title binuclear μ-pyridyl-vinyl-idene FePd complex (FePd1) as a benzene solvate, [FePd(C5H5)(C7H5N)I(CO)2]·C6H6, in a very low yield rather than the expected iron o-pyridyl-ethynyl complex Cp(CO)2Fe-C≡C-(2-C5H4N). The Fe and Pd atoms in FePd1 are bridged by carbonyl and pyridyl-vinyl-idene ligands, the pyridyl N atom being bonded to the palladium atom. The use of equimolar amounts of PdCl2 increases the yield of FePd1 to 12%. The reaction pathway leading to FePd1 is proposed.

Tungsten-183 NMR study of cis-[W(CO)4(PPh3)(4-RC5H4N)]; effect of varying the σ donor strength of the pyridine

Tungsten-183 NMR data are reported for the complexes cis-[W(CO)4(PPh3)(4-RC5H4N)] (R = H, Me, Ph, COMe, COPh, OMe, NMe2, Cl, NO2). The (183)W chemical shift (obtained by indirect detection using (31)P) is found to correlate with the Hammett σ function for the group R, with (183)W shielding increasing approximately linearly with the donor strength of the pyridine over a range of 93 ppm. The X-ray structures of cis-[W(CO)4(PPh3)(4-MeOC5H4N)] and cis-[W(CO)4(PPh3)(4-PhCOC5H4N)] are also reported.

Synthesis and characterization of new chromium, molybdenum and tungsten complexes of 2-[2-(methylaminoethyl)] pyridine

A green chemistry route of synthesis using direct sunlight irradiation for the reactions of [M(CO)(6)] M=Cr, Mo or W with 2-[2-(methylaminoethyl)] pyridine (maepy) in THF. The reactions resulted in the formation of the oxo complex [Cr(2)(O)(4)(maepy)(2)] (1) and the tetracarbonyl complexes [Mo(CO)(4)(maepy)] (2) and [W(CO)(4)(maepy)] (3). The prepared complexes were characterized by elemental analysis, IR, NMR, mass spectrometry and magnetic measurement. The complexes (1-3) were further investigated by thermogravimetric technique (TG). The biological activity of maepy and complexes as antibacterial and antifungal reagents have been investigated.

Synthesis, characterization and biological activities of some new chromium molybdenum and tungsten complexes with 2,6-diaminopyridine

The reactions of [M(CO)6], M=Cr, Mo, W with 2,6-diaminopyridine (dap) in ethanol was carried out under sun light and microwave irradiation routes of synthesis and compared with the traditional thermal reflux method. All routes resulted in the formation of the binuclear oxo complexes with the general formulas [M2(O)4(dap)2]. The prepared complexes were characterized using elemental analysis, IR, 1HNMR, mass spectrometry and magnetic measurement. The biological activity of dap and its complexes as antibacterial and antifungal reagents have been screened.

From simple monopyridine clusters [Mo6Br13(Py-R)][n-Bu4N] and hexapyridine clusters [Mo6X8(Py-R)6][OSO2CF3]4 (X = Br or I) to cluster-cored organometallic stars, dendrons, and dendrimers

Hexasubstitution of apical triflate ligands in the octahedral clusters [M]2[Mo6X8(CF3SO3)6] (M = n-Bu4N or Cs, X = Br or I) and monosubstitution in [n-Bu4N]2[Mo6Br13(CF3SO3)] was carried out in tetrahydrofuran at 60 degrees C with simple pyridines and then extended to organometallic pyridines, yielding cluster-cored stars, and to dendronic polyallyl- and polyferrocenylpyridines, yielding cluster-cored polyallyl and polyferrocenyl dendrimers and dendrons. The orange pyridine-substituted clusters, whose pyridine protons are deshielded in 1H NMR (a practical tool for characterization), are air-stable and thermally stable with simple pyridines, light- and air-sensitive with organometallic pyridines, and air-fragile and thermally fragile with large dendronized pyridines.