Comparison of tetrel bonds in neutral and protonated complexes of pyridineTF3and furanTF3(T = C, Si, and Ge) with NH3

Protonation not only changes the primary interaction mode between α/β-furanCF3/p-PyCF3and NH3but also prominently enhances the strength of the Si/Ge⋯N tetrel bond.

Interaction of Acenannulated Metallotetraazaporphyrins with the Lewis Acid Aluminum Bromide

Interaction of metal complexes of linearly benzo-annulated tetraazaporphyrins such as tetra-tert-butyltetrabenzoporphyrazine, tetra-tert-butyltetranaphthoporphyrazine, and octaphenyltetraanthra-porphyrazine, with the Lewis acid AlBr 3 in nitrobenzene and ethylbromide has been studied by absorption spectroscopy. The interaction is characterized by stepwise formation of several protonated complexes with the superacid H +[ AlBr 4]−. Mono-, di-, tri- and tetraprotonated species can be formed. The absorption maxima are shifted up to 1300 nm depending on annulation, metal ion and concentration of the Lewis acid.

Copper complexes of polyfunctional phthalazines. Mononuclear and polynuclear derivatives

Mononuclear, binuclear, and trinuclear copper(II) complexes of the tetradentate ligands 1,4-di(2′-pyridyl) aminophthalazine (PAP) and 1,4-di(4′-methyl-2′-pyridyl) aminophthalazine (PAP4Me) and binuclear complexes of the tetradentate ligand 1,4-di(6′-methyl-2′-pyridyl) aminophthalazine (PAP6Me) are reported. In a series of binuclear carboxylate derivatives carboxylate bridges exist between copper centres in all cases and in some cases oxygen bridges (hydroxide or methoxide) are indicated. In all other polynuclear derivatives hydroxide bridges are anticipated on the basis of analytical, spectral, and magnetic data. The ligands exist as anionic groups in some binuclear carboxylate derivatives while in the other polynuclear systems neutral ligands are found. In reactions in aqueous solution protonated mononuclear derivatives are obtained for both PAP and PAP4Me in cases where solutions of the metal salts are inherently acidic, followed by polynuclear, neutral ligand complexes which form when the pH increases. Mononuclear protonated complexes are not obtained with PAP6Me, where steric factors may prevent the formation of such derivatives. Low magnetic moments (1.1–1.5 BM) are observed for most hydroxy bridged complexes while even lower values ( < 0.70 BM ) are observed for two binuclear complexes of PAP6Me, indicating the possibility of strong antiferromagnetic exchange between metal centres. A preliminary X-ray investigation of the complex [Cu2(PAP4Me)(OH)(NO3)2(H2O)2]NO3 indicates a triple bridged binuclear structure including a bidentate nitrate bridge and a hydroxide bridge with an oxygen bridge angle of 115.2°.