P. S. Koroteev

Synthesis, structure, solid-state thermolysis, and catalytic properties of binuclear Ce, Nd, Eu, and Gd cymantrenecarboxylate complexes with DMSO

New rare-earth cymantrenecarboxylate complexes [Ln2(μ,η2-O2CCym)2(μ2-O2CCym)2-(η2-O2CCym)2(DMSO)4] (Cym = (η5-C5H4)Mn(CO)3, Ln = Ce (1), Nd (2), Eu (3), Gd (4)) were synthesized and characterized by X-ray diffraction. In dimeric structures 1–4, two of four bridging carboxylates are chelating-bridging, and Ln atoms have coordination number 9. The catalytic activity of complex 2 in the polymerization of 2,3-dimethyl-1,3-butadiene was investigated. The thermal decomposition of the synthesized compounds was studied by DSC and TGA. According to the X-ray powder diffraction data, the final thermal decomposition product of 1 in air consists of CeO2 and Mn3O4. Under the same conditions, complexes 2–4 afford mixtures of LnMn2O5 and Mn2O3.

New binuclear ferrocenecarboxylates of rare-earth metals as precursors for ferrites: Syntheses, structures, and solid-phase thermolysis

New ferrocenecarboxylates of rare-earth metals, [Ln2(μ-O,η2-OOCFc)2(μ2-O,O′-OOCFc)2(η2-NO3)2(DMSO)4] (Ln = Gd (I), Tb (II), and Y (III)) and [Gd2(μ-O,η2-OOCFc)2(η2-OOCFc)4(DMSO)2(H2O)2] · 2DMSO · 2CH2Cl2 (IV), are synthesized and characterized by X-ray diffraction analysis. Unlike all earlier known ferrocenecarboxylates of rare-earth metals, in isostructural compounds I–III the Ln atoms are linked by four bridging carboxyl residues, two of which are chelate-bridging (the coordination number of Ln is 9). Binuclear structure IV is formed by two chelate-bridging carboxylate ligands (the coordination number of Gd is 9). Weak antiferromagnetic and weak ferromagnetic interactions between the Gd atoms are observed in complexes I and IV, respectively. The thermal decomposition of the synthesized compounds is studied by differential scanning calorimetry and thermogravimetry. According to the X-ray diffraction data, the final thermolysis products of the complexes in air are garnets Ln3Fe5O12.

Binuclear and Polynuclear Cymantrenecarboxylate Complexes of Heavy Lanthanides

New binuclear cymantrenecarboxylate complexes of rare-earth metals, [Ln2(μ-O,η2-O2CCym)2(μ2-O,O′-O2CCym)2(η2-O2CCym)2(DMSO)4] (Ln = Tb (I), Dy (II); Cym = (η5-C5H4)Mn(CO)3) and [Ln2(μ2-O,O′-O2CCym)4(η2-NO3)2(DMSO)4] (Ln = Tb (III), Dy (IV)), are synthesized and characterized by X-ray diffraction analysis. The carboxylate clusters containing the Mn2+ ion, which is formed due to the destruction of the cymantrenenecarboxylate anion, [Tb4(μ3-OH)4(μ2-O,O′-O2CCym)6(H2O)3(THF)4][MnCl4] · 4CH2Cl2 · 6THF (V) with the cubane-like structure, and [Er2Mn(μ2-O2CCym)6(η2-O2CCym)2((MeO)3PO)4] · 2MePh (VI) with linear structure, are also obtained. The magnetism of complexes I, II, V, and VI is studied in a direct magnetic field. The magnetic properties of complexes II and VI are studied in direct and alternating magnetic fields. Complex II exhibits the properties of a single-molecule magnet. The thermal decomposition of complexes I–IV is studied by differential scanning calorimetry and thermogravimetric analysis. According to the X-ray diffraction analysis data, the final thermolysis products of complexes III and IV in air are multiferroics LnMn2O5.

Magnetostructural correlation for the Gd complexes with bridging oxygen

The dependence between the energy of magnetic exchange interaction JGd-Gd′ and the distance between gadolinium atoms in the binuclear structure DGd...Gd′ was constructed on the basis of our and literature experimental data for 34 gadolinium complexes with the [Gd2O2] core. The character of the established dependence is similar to the Bethe-Slater curve. The obtained correlation indicates the possibility to predict the character of interaction in the Gd complexes built of binuclear fragments with the [Gd2O2] core depending on the single parameter, namely, distance DGd...Gd′. The validity of this correlation was tested using as examples four binuclear gadolinium complexes obtained by the authors.

Thermal behavior of samarium binuclear pivalate and tris-pivalate

Kinetic analysis of the thermolysis of samarium pivalate [Sm2(μ2-OOCCMe3)4(OOCCMe3)2(HOOCCMe3)6] · HOOCCMe3 (1) was carried out (the input data were differential scanning calorimetry (DSC) and thermogravimetry data), and a mathematic model of the process was developed that allowed us to optimize (by calculation) the conditions for formation of {Sm(OOCCMe3)3}n (2) samarium tris-pivalate via thermal decomposition of complex 1. The results of the thermal study of samarium and gadolinium tris-pivalates in the temperature range of −50…+50°C are reported. Specific anomalies were found in the DSC curves and heat capacity versus temperature curves in the temperature range of 0–50°C.

Polymer lanthanide cymantrenecarboxylates

Polymer cymantrenecarboxylate complexes of rare-earth metals, [Ln(η2-O2CCym)2(µ-O2CCym)4Ln(ROH)4]n · mSolv (Ln = Nd (I), Gd (II), Dy (III), Ho (IV), Er (V, Va); R = H and Me; Cym = (η5-C5H4)Mn(CO)3; Solv is a solvent molecule), are synthesized by the exchange reactions between LnCl3 and CymCO2K in aqueous–organic media. Two types of coordination sites alternate in the polymer chain: Ln3+ ions coordinating water or methanol molecules and oxygen atoms of the carboxylate anions and Ln3+ ions coordinating oxygen atoms of the bridging and chelate carboxylate anions. In both cases, the coordination number of Ln is 8. Polymer [Dy4(O2CCym)12(HOCH2CH2OH)3.76(H2O)0.48]n · 3nTHF (VI) containing four crystallographically independent Dy3+ ions is obtained when ethylene glycol is used instead of methanol. The thermal behavior of complexes I–V in argon and magnetism of complexes II, III, and IV are studied. Complex III exhibits the properties of a single-molecule magnet with the chain structure (single-chain magnet) (CIF files CCDC 1410905 (I), 1410917 (II), 1410906 (III), 1410911 (IV), 1410918 (V), and 1410934 (VI)).

Reaction of the PtIII complex, [Pt2(μ-NHCOMe)4Cl2], with 1,10-phenanthroline and solid-state thermolysis of 1,10-phenanthroline-containing platinum blues

Platinum blues with the composition Pt(phen)(NHCOMe)2X (phen is 1,10-phenanthroline, X = NO3−, CF3SO3−, or Cl−), were synthesized starting from the complex [Pt2(NHCOMe)4Cl2]. The resulting compounds apparently have a polymeric structure with metal centers in different valence states. The reaction of the complex Pt(phen)(NHCOMe)2NO3 with H2O affords crystalline binuclear acetamidate [PtIII2(phen)2(μ-NHCOMe)2(NHCOMe)2](NO3)2, whose structure was determined by X-ray diffraction. The reaction of the complex Pt(phen)(NHCOMe)2NO3 with HCF3SO3 leads to the decomposition of the starting compound, the reduction of the Pt atoms, and the formation of the complex [PtII2(phen)4](CF3SO3)4. The thermal decomposition of the resulting complexes, as well as the complexes [(phen)Pt-(μ-NHCOMe)2Pt(phen)]2(NO3)4 and [Pt(phen)Cl2], under an inert atmosphere was studied by DSC and TGA. Metallic platinum nanopowders are thermal decomposition products of the complexes under study.

Thermolysis specifics of Tin(IV) and Tin(II) complex derivatives: Thermolysis of (Acac)2SnX2 (X = Cl, N3), (CO)5MSnCl2(thf) (M = Cr, Mo, W), (CO)5MSn(Acac)2, (CO)5MSn(SCN)2, (CH3)4N(CO)5MoSnCl3 (M = Cr, W), and (CO)2MnCpSnCl2(thf)

Differential scanning calorimetry and thermogravimetry are used to study the thermolysis of following complexes: (Acac)2Sn(N3)Cl (1); (Acac)2SnCl2 (2); (CO)5MSn(Acac)2 with M = Cr (3) or W ((4)), (CO)5MSnCl2(thf) with M = Cr (5), Mo (6), or W (7)), (CH3)4N(CO)5MSnCl3 with M = Mo (8) or W ((9)), (CO)2MnCpSnCl2(thf) (10)); and (CO)5MSn(SCN)2 with M = Cr (11) or W (12). The phase composition of the solid thermolysis products of compounds 1–5 and 7–12 is determined by X-ray powder diffraction. Thermolysis schemes are suggested.

Specific features of the structure, reactivity, thermolysis, and magnetism of cymantrenecarboxylate complexes of lanthanides

The properties of the cymantrenecarboxylate (containing (CO)3 Mn(η5-C5H4CO2- group) complexes of lanthanides obtained and studied by the authors in the years 2009–2015 are reviewed. The complexes represent a new type of heterometallic 3d–4f compounds. Both binuclear and polymer complexes of various types are synthesized. The variation of the synthesis conditions and the use of additional ligands make it possible to successively change the Mn: Ln ratio in a molecule of the compounds and to obtain the ratio equal to 3: 1, 2: 1, and 1: 1. The polymeric heteroleptic derivatives, acetate and acetyacetonate cymantrenecarboxylates, are synthesized. Using the photolabile cymantrene fragment as a source of Mn2+ ions, polynuclear Mn–Ln heterometallic cymantrenecarboxylates are obtained under the oxidative photolysis conditions. The influence of binuclear neodymium cymantrenecarboxylate on the polymerization of dienes is studied. The structures of the complexes, their physicochemical properties, and possibilities of practical application are considered.

Synthesis, structure, and magnetic properties of lanthanide ferrocenoylacetonates with nitrate and 2,2′-bipyridine ligands

Abstract Ferrocenoylacetonate complexes of several lanthanides, [Ln(fca)2(NO3)(bpy)]·nMeC6H5 (Ln = Sm (1), Dy (3), Er (4), Yb (5), n = 1; Eu (2), n = 0.5; fca = FcC(O)CHC(O)Me; bpy = 2,2′-bipyridine), were synthesized and characterized by X-ray single-crystal analysis. Complexes 1, 4, and 5 are isostructural; 2 has a similar molecular structure with cis-disposition of fca ligands. The molecular structure of 3 is different, with trans-disposition of the fca ligands. Crystal lattices of the complexes are stabilized by π-stacking interactions. The Ln3+ ions in the complexes are eight-coordinate. According to mass spectroscopic data, the complexes are unstable in the gas phase. Magnetic properties of 2 and 4 were studied in a DC field; for 4, AC studies were also carried out. The values of spin-orbital parameters obtained using two estimation methods for 2 are in satisfactory agreement. Slow relaxation of the magnetization was found for the Er complex.