Koordinacionnaâ himiâ

The mononuclear nickel(II) complex [L₂Ni(CH₃OH)]Cl (I) was synthesized by the interaction of new ligand 2-(2,6-dichlorophenyl)-5-(pyridin-2-yl)-2,4-dihydro-3H-pyrazol-3-one (L) with nickel(II) chloride. The solvate of complex I with methanol [L₂Ni(CH₃OH)]Cl·3CH₃OH and the initial ligand L were characterized by X-ray diffraction analysis (CCDC № 2314989 (I), 2314988 (L)). It was observed that ligand L exists in the pyrazolone form based on ¹H NMR data, whereas in complex I, it is found in the pyrazolol form according to X-ray diffraction data. Complex I is a unique example of a pyrazolol complex in which the oxygen atom does not engage in coordinating with the transition metal ion to create the coordination polymer.

The reaction of cobalt(II) trimethyl acetate (pivalate) [Co(Рiv)₂]_n (HРiv = HO₂CCMe₃) with 1,4-diaminobutane (Dab) in absolute acetonitrile gave a 2D-coordination polymer [Co(Piv)₂(Dab)₂]_n (I) with an admixture of the co-product, but the addition of one equivalent of 2,2´-bipyridine to the reaction mixture made it possible to isolate a single-phase sample of I (according to X-ray diffraction data) with a yield of 78%. The crystal structure of I was determined by X-ray diffraction (CCDC No. 2404406): cobalt(II) atoms in a distorted octahedral environment (CoN₄O₂) of two monodentate carboxylate groups and four bridging Dab molecules form a layered coordination polymer with a honeycomb-like hcb topology. The thermal behavior of I was studied by synchronous thermal analysis: thermal decomposition leads to the formation of the organic salt (H₂Dab)(Piv)₂, cobalt(II) pivalate, and the octanuclear complex [Co₈O₂(Piv)₁₂] — the products were identified by XRD and NMR spectroscopy.

New nickel(II) pincer complexes based on the pentamethylruthenocene, NiCl[{2,5-(R₂PCH₂)₂C₅H₂}Ru(Cp^*)] (Cp* = C₅Me₅, Ia: R = ^tBu; Ib: R = ⁱPr) were synthesized via a two-step route starting from the 1,3-functionally substituted diol {1,3-(HOCH₂)C₅H₃}Ru(Cp*). In the first step, diol was reacted with dialkylphosphines (^tBu₂PH, ⁱPr₂PH) in acetic acid to give diphosphines {1,3-(R₂PCH₂)₂C₅H₃}Ru(Cp*) (R = ^tBu; ⁱPr), which were not isolated in a pure state, but after the removal AcOH, was immediately subjected to cyclometallation with nickel(II) chloride hexahydrate in the presence of pyridine. After all purification procedures, the yields of products Ia and Ib were 31 and 16%, respectively. The complexes were fully characterized by ¹H, ³¹P{¹H}, and ¹³C{¹H} NMR spectroscopy. The purity of the products was confirmed by elemental analysis. The structure of complex Ia was established by single-crystal X-ray diffraction (CCDC № 2408463).

A series of acetate and trifluoroacetate compounds of cobalt(II) with derivatives of 3-arylidene-1-pyrrolines (X-L; X = Cl, OH) as N-donor ligands was synthesized. Varying the synthesis and crystallization conditions made it possible to obtain coordination compounds of various compositions and structures: a tetranuclear complex based on a cubane fragment {Co₄(OH)₄}^4– — [Co₄(OH)₄(Cl–L)₄(OAc)₄] (I), a 1D-polymer complex [Co(H₂O)(Cl–L)₂(CF₃COO)_1.167(OAc)_0.833]_n (II) or a molecular complex [Co(OH–L)₂(OAc)₂] (III). The synthesized compounds were characterized by X-ray diffraction, IR spectroscopy and CHN analysis. The structure and crystal packing of the obtained complexes were analyzed in detail, the main structure-forming non-covalent interactions in crystals were identified.