SYNTHESIS AND SPECTRAL CHARACTERISTICS OF THE Ru(III,ІІ), Rh(III) AND Pd(II) COMPLEXES BASED ON N-ALLYLTHIOAMIDES AND PRODUCTS THEIR PROTON- AND IODOCYCLIZATION
Authors: Borovyk Polina , Litvinchuk Mariia , Bentya Anton , Orysyk Svitlana , Zborovskii Yuri , Orysyk Viktor , Pekhnyo Vasyl , Mykhailo Vovk 
Published: May 2020

The paper shows the possibility of using N-allylthioamides H2L1-H2L3 and products of their proton / iodine cyclization HL4, HL5 as chelating agents in the complexation reactions with Ru(III,II), Rh(III) and Pd(II) ions. As a result, a series of new chelating complexes of [M(HL1-3)Cl2(H2O)2], [M(HL1-3)2(H2O)2]Cl (2), [М(HL1-3)2(H2O)Cl] (3), [Ru(HL1-3)(PPh3)2]Cl (4), K[Pd(HL1-3)Cl2] (5), [Pd(HL1-3)2] (6), [M(L4,5)2(H2O)2]Cl (7), K[Pd(L4,5)Cl2] (8), [Pd(L4,5)2] (9) in which the ligands are coordinated to the metal ions by O,S- or O,N-bidentate chelate manner in a monodeprotonated form, where synthesis, isolated in solid state and characterized by the methods of elemental chemical analysis, 1H NMR, IR and UV-Vis spectroscopy. It was found that HL4,5, when complexed, is converted to the corresponding tautomeric form with O,N-coordination through the oxygen atoms of the deprotonated hydroxyl group and the nitrogen atoms of the dihydrothiazolyl ring. It has been established that the allyl moiety does not participate in the formation of a coordination bond with the Ru (III,II), Rh(III) and Pd(II) ions, which is probably due to the presence in the molecules of ligands of other donor nucleophilic centers located in advantageous position for the formation of six-membered chelated metal cycles. In contrast to complexes 1-9, the compounds of [M(HL6)2(H2O)2Cl2]Cl (10), [Pd(HL6)2Cl2] (11) based on 2-(5-(iodomethyl)-1,3-thiazolidin-2-ylidene) malononitrile (HL6) were obtained with monodentate coordination of the ligand in molecular form, which is caused by the presence of two nitrile groups in the HL6 molecule with sp-hybridization of the nitrogen atomic orbitals, which provides almost linear overlap with the d-orbitals of the metal atom upon formation of CN→M bond. The study of the complex formation of metal chlorides with H2L1-H2L3 by the method of isomolar series and UV-Vis spectra showed that there is interaction in the M: L = 1:1, 1:2, 1:3 molar ratio (in the case of Ru3+, Rh3+ ions) and 1:1, 1:2 (in the case of Pd2+ and Ru2+ ions) which is related to the coordination capacity of metals and their ability to form octahedral (for Ru3+, Rh3+ ions) or square-planar (for Pd2+ ions) coordination unit. The reaction of Ru3+, Rh3+ and Pd2+ ions with HL4, HL5 in the isopropanol solution also occurs in the ratio M:L = 1:1, 1:2, 1:3, however, the titration curves are much less pronounced compared to complexes based on H2L1-H2L3. In the interaction of HL6 with the ions of the above metals, the curve has the appearance of an almost straight line, indicating the so-called "state of unsaturation" of the system in the corresponding concentration range due to the monodentate coordination of HL6. The solubility study of the obtained complexes showed that ionic type compounds 2, 4, 5, 7, 8, 10 were dissolved in methanol, partially (or completely) in ethanol, and at low concentrations (10-3-10-5 mol/l) - in water, while molecular type compounds 1, 3, 6, 11 are soluble in DMSO and DMF only.