The isolation and investigation of molecular complexes formed between porphyrins and aromatic nitro-compounds

Hydrogen bonding to coordinated imidazole. Association of 1,10-phenanthroline and other bases with bis(imidazole)metalloporphyrins

“…Comparison of this value with the ¡»(CO) force constants of 17.6 and 17.1 mdyn/A found for jCpFe(CO)3)PF616b and {Cp(CO)2FeCNCH3|PF6,16b respectively, indicates that the dithiocarbene ligand has a lower 7r-acceptor/ff-donor ratio than either the carbonyl or isocyanide ligand, which is consistent with conclusions drawn for other transition-metal carbene complexes. 3 The position of the carbene carbon resonance in the I3C NMR (acetone-<f6) spectrum of Ila occurs at 303 ppm downfield relative to Me4Si, which is also consistent with previous reports. 3 A single line at 6.73 is observed for the two methyl groups of the carbene ligand in the NMR (acetone-<f6) spectrum of Ila.…”

“…3 The position of the carbene carbon resonance in the I3C NMR (acetone-<f6) spectrum of Ila occurs at 303 ppm downfield relative to Me4Si, which is also consistent with previous reports. 3 A single line at 6.73 is observed for the two methyl groups of the carbene ligand in the NMR (acetone-<f6) spectrum of Ila. This is in contrast with spectra reported for jPtCl-…”

“…Other such x complexes of metalloporphyrins are characterized by one or more of the following: new absorption bands, shifts in absorption maxima, alteration in the extinction coefficients of absorption bands due to broadening of the absorption bands. 3,4 No changes of this sort are evident in the 1,10-phenanthroline-imidazole-FePCl systems. Moreover 1,10-phenanthroline has no effect on equilibrium 1 when the base is 1-methylimidazole as may be seen by trace F of Figure 1.…”

Organometallic photochemistry at the solid/gas interface. Photochemistry of surface-confined cobalt tetracarbonyl monitored by Fourier transform infrared photoacoustic spectroscopy

“…Only ¿¡connected nitrogen atoms, such as the skeletal nitrogen atoms of phosphazene rings, are expected and were shown to have a high enough basicity to easily give transition-metal adducts.7 •8 Reaction 1 can be reversed under the action of an acid: bubbling HC1 into a THF solution of la at room temperature converts it quantitatively to 3b.1 Upon heating for 4 h in THF at 60 °C, adduct la converts to the deep red compound 5, which was formerly synthesized by allowing LiMe to react with the hexafluorophosphate salt 3c. 6 Similar behavior was observed with the tungsten analogue of 3a, yielding the orange-yellow crystalline compound lb (31P NMR 26.4, Jp.w = 232 Hz) whose spectral and analytical data are consistent with the same formulation.…”

Thermodynamic investigation of the molecular interactions of 4-nitrophenol with free-bases meso-tetraarylporphyrins

“…Ultraviolet-visible (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopies are traditionally used for investigation of noncovalent complexes based on the hydrogen bonds (HB) interactions between a receptor and its substrate. The molecular interactions of free-base porphyrins with acceptor molecules, such as nitroaromatic systems [1][2][3][4][5][6][7][8][9] have been the subject of a considerable number of studies. The interaction of phenol derivatives, such as 4-nitrophenol (4NP) [1,2], 2,4-dichlorophenol (2,4-DCP) [3], 2,4,6-trichlorophenol (2,4,6-TCP) [4] and pentachlorophenol [10], with water-soluble porphyrins and other biological systems are of interest.…”