L. B. Volodarskii

Complexes of metals with paramagnetic enaminoketone

Conclusions1.The authors have synthesized the paramagnetic intracomplex compounds of Co(II), Ni(II), Cu(II), Zn(II), and Pd(II) with 4-phenacetylidene-2,2,5,5-tetramethyl-3-imidazolidine 1-oxide, and also heteroligand complexes based on the chelate of Ni(II).2.The chelates of Co(II), Ni(II), and Zn(II) are a new group of compounds with distorted-tetrahedral coordination of the metal.3.In the complexes at 20°C, J>kT.

Intramolecular spin exchange in palladium (II) complexes with imidazoline nitroxyl radicals

Conclusions1.The temperature dependence of the ESR spectra of solutions of Pd(II) complexes with imidazoline nitroxyl radicals PdL2 and [PdLX]2 (X=C1, Br, I) was investigated.2.In all the investigated complexes the spin-exchange process is realized by an indirect mechanism.3.A relation was established between the effectiveness of the delocalization of electron spin density and the nature of the bridging halogen atom and the structure of the chelating ligand (the nitroxyl radical).

Complexes of metals with paramagnetic hydroxamic acid

Conclusions1.The authors have synthesized and investigated complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with paramagnetic hydroxamic acid.2.Using the ESR method they have established the presence of indirect exchange interaction between the unpaired electrons of the paramagnetic centers of molecules of these complexes.

Dimeric complexes of Pd(II) with imidazoline nitroxyl radical that contain the Pd-C bond and halogen bridge atoms

Conclusions1.The orthometalation reaction was used to synthesize some Pd(II) complexes that contain a stable radical with the Pd-C bond.2.It was established that the complexes have a dimeric structure and bridge halogen atoms.

Palladium(II) chloride compounds with stable biradicals of imidazoline

ConclusionsThe first coordination compounds of stable nitroxyl biradical imidazolines have been synthesized. From the spectral data obtained, the paramagnetic ligand 4,4′-(ethyleneiminomethyl)di-2, 2,5,5-tetramethyl-3-imidazoline-1-oxyl acts as a tetradentate bridge in a binuclear coordination compound with Pd(II), while the azine ligand 4-formyl-2,2,S,5-tetramethyl-3-imidazoline-1-oxyl acts as a bidentate bridge.

Coordination compounds of Cu(II) with the nitroxyl radical 2-acetyl-2,5,5-trimethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl thiosemicarbazone and its 1-hydroxy derivative

Conclusions1.During the formation of complexes of Cu(II) with 2-acety1-2,5,5-trimethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl thiosemicarbazone, which has a donor functional group adjacent to the radical center, in methanol, chloroform, CH2Cl2, or acetone, the nitroxyl group of the ligand is reduced to the hydroxylamine. In alkaline solution, on the other hand, in the presence of Cu(II) salts the hydroxylamine group of 2-acety1-2,5,5-trimethy1-4-phenyl-3-imidazoline-1-hydroxy-3-oxide thiosemicarbazone is converted into the nitroxyl.2.The coordination compound with the nitroxyl radical is diamagnetic, apparently owing to strong antiferromagnetic interaction between the unpaired electrons of the paramagnetic centers arising as a result of coordination of the group by the Cu(II) ion.

Determination of metals with the aid of stable nitroxide radicals

1. Palladium is practically quantitatively extracted from acidified aqueous solutions of K2PdCl4 by a solution of 4-hydroximinomethyl-2, 2,5,5-tetramethyl-Δ3-imidazolino-1-oxyl in chloroform. 2. The possibility of a spectrophotometric determination of palladium was demonstrated. 3. Pd(II), which has acquired a spin label in the interaction with a paramagnetic ligand, can be quantitatively determined by the ESR method.

Volatile coordination compounds of Ni2+ and Co3+ with 1,2-hydroxylaminooximes

Complexes of Ni2+ and Co3+ with the deprotonated anions of the new ligand N-(3-oximino-2,4-dimethylpentyl-2)hydroxylamine are prepared. The compounds synthesized sublime in vacuum.

Complexation of palladium(II) and copper(II) halides with the stable 4-methyliminomethyl-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl radical and the addition of alcohols

Conclusions1.Coordination compounds of palladium(II) and copper(II) halides with 4-methyliminomethyl-2,2,5,5-tetramethyl-3-imidazolin-1-oxyl have been synthesized.2.When copper(II) halide reacts with 4-methyliminomethyl-2,2,5,5-tetramethyl-3-imidazolin-1-oxyl in anhydrous alcohols, a molecule of alcohol adds at the C=N bond of the aliphatic segment of the starting ligand. The coordination compounds that form by this reaction of the coordinated ligand were isolated.