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Carboxycymantrene CymCOOH (Cym = (η5‐C5H4)Mn (CO)3) was applied to assemble a series of uncommon Cd‐Mn carboxylate complexes comprising 1D‐polynuclear [Cd (OOCCym)(acac)]n (1) as well as oligonuclear species, [Cd2(OOCCym)4(EtOH)4)] (2), [Cd (OOCCym)2(bpy)(H2O] (3, bpy = 2,2′‐bipyridine) and [Cd (OOCCym)2(phen)2]·EtOH (4, phen = 1,10‐phenantroline). Compound 2 was found to be a product of irreversible SCSC transition from [Cd2(OOCCym)4(EtOH)3(H2O)]·EtOH (2_100K) initially formed in corresponding syntheses. This transition is accompanied by two‐fold decrease in cell volume and increase in cell symmetry. Recrystallyzation of 2–4 from common organic solvents affects the nuclearity of products (in case of 2 and 3) or subtly alters the structure of [Cd (OOCCym)2(phen)2] units (4). The optimal Cd to Mn ratio inspired studying solid‐state thermal decomposition of 2–4 as a route to CdMn2O4‐based ceramics. As a result, oxide samples with a predominance of tetragonal (Cd1‐xMnx)Mn2O4 spinel have been prepared and characterized by powder XRD, SEM, EDX, and IR revealing the interplay between the preparation technique and the features of morphology and composition. The retaining of Cd to Mn ratio upon recrystallyzation of 2–4 implies possibility of further elaboration of CdMn2O4‐based materials in various morphologies (polycrystalline ones, films, etc.). Notably, 2–4 is also the first series of related heterometallic Cd‐Mn complexes being studied as individual precursors for CdMn2O4‐based oxide systems. [ABSTRACT FROM AUTHOR]

Complexes [Gd2(piv)6(bath)2]⋅2EtOH (1a⋅2EtOH), [Gd2(piv)6(bath)2]⋅1.5EtOH⋅0.5H2O (1b⋅1.5EtOH⋅0.5H2O), and [Gd2(piv)6(bath)2]⋅H2O (1c⋅H2O), where piv is (CH3)3CCO2− and bath is 4,7‐diphenyl‐1,10‐phenanthroline, which have different molecular and crystal structures, were synthesized and studied by X‐ray diffraction. A unique feature of polymorphs 1a, 1b, and 1c is that they exhibit first‐order phase transitions, namely, structural phase transitions, or melting before thermal decomposition. Magneto‐structural data for binuclear gadolinium pivalates with bath (1), bpy (2), phen (3), and Hpiv (4) ligands and the polymeric complex [Gd(piv)3]n (5) are presented. The complexes were characterized by ESR spectroscopy. The energies of the excited singlet S1 and triplet T1 states of the bath ligand in carboxylates 1a⋅2EtOH, 1b⋅1.5EtOH⋅0.5H2O, and 1c⋅H2O were determined. [ABSTRACT FROM AUTHOR]

Exchange reactions of LnCl3 and CymCO2K in aqueous‐organic medium in the presence of diethylene glycol (DEG) bring about isostructural tetranuclear cluster complexes with linear core, [Ln4(CymCO2)12(O(CH2CH2OH)2)2(H2O)4] ⋅ 2THF (Ln=Nd (1), Gd (2), Tb (3), Dy (4), Ho (5); Cym=(η5‐C5H4)Mn(CO)3). The complexes have centrosymmetric structure and contain two types of Ln3+ coordination centers. Thermal decomposition of the complexes under argon and air atmospheres was studied; in the latter case it brings about mixed oxides LnMn2O5 as one of the products. The complexes 1–5 were characterized by dc‐ and ac‐magnetic measurements. Complexes of Nd, Gd, and Dy exhibit the properties of single‐molecule magnets (SMMs) with remagnetization barriers Δeff/kB of 14 K for 1 under 2500 Oe dc‐field, 13 K for 2 under 1500 Oe dc‐field, and with two barriers, 18 and 19 K, for 4 in zero field. The presence of field‐induced slow relaxation of the magnetization detected for the complex 2 is a rare case for Gd complexes. [ABSTRACT FROM AUTHOR]

Two series of novel heteroleptic derivatives of lanthanides and (η6-benzoic acid)tricarbonylchromium (benchrotrenecarboxylic acid) were synthesized and characterized: mononuclear complexes [Ln(BcrCOO)(acac)2(H2O)2] (Ln = Eu (1), Gd (2), Tb (3a), Dy (4a), Ho (5a)) and 1D-polymeric ones [Ln(BcrCOO)(acac)2(H2O)]n (Ln = Tb (3b), Dy (4b), Ho (5b), Er (6), Tm (7), Yb (8) and Y (9)), Bcr = (η6-C6H5)Cr(CO)3. The molecular and crystal structures of the obtained compounds were determined. Complexes 3a, 4a, 4b, 6 and 8 were found to exhibit SMM properties. Two maxima were observed on χ′′(ν) dependencies (LF and HF) for 4a, 4b and 6. For 4a, the anisotropy barriers are Δeff/kB = 100 K and 118 K in zero dc-field (128 K and 143 K in 2000 Oe field) for the LF (low frequency) and HF (high frequency) signals, respectively. These values are the highest ones for Ln carboxylate complexes. The nature of the appearance of two maxima in the system is discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] 3d–4f-heterometallic “defective dicubane” cymantrenecarboxylates were synthesized. [•] Thermolysis of obtained complexes under air affords LnMn2O5 and Mn2O3 phases. [•] Dy complex exhibits the properties of single molecule magnet. [Copyright &y& Elsevier]

Abstract: New binuclear rare-earth cymantrenecarboxylate complexes [Ln2(μ2-OOCCym)2(μ-О,η2-OOCCym)2(η2-NO3)2(η2-DME)2], Ln=Pr (1), Eu (2), Gd (3), Tb (4a), Dy (5), Ho(6a), Er (7); [Ln2(μ2-OOCCym)4(η2-NO3)2(η2-DME)2], Ln=Tb (4b), Ho(6b,c), Yb (8) and the trinuclear complex [Yb3(μ-О,η2-OOCCym)2(μ2-OOCCym)4(η2-NO3)3(η2-DME)2(H2O)2] (9) (Cym=(η5-C5H4)Mn(CO)3), DME=CH3OCH2CH2OCH3) were synthesized and characterized by X-ray diffraction. The magnetic properties of 3 are indicative of antiferromagnetic exchange between the Gd atoms. Complexes 4a and 6a were found to exhibit significant ferromagnetic interactions. It was shown that the luminescence of Eu3+ in 2 is efficiently quenched by the cymantrenecarboxylate moiety which determines the luminescent properties of this complex. For complex 4a standard thermodynamic functions were calculated from adiabatic calorimetry data. The thermal decomposition of the complexes in air affords pure LnMn2O5 phases as the final products. The magnetic properties of the LnMn2O5 phases (Ln=Gd, Ho) prepared by the thermal decomposition of 3 and 6a were studied. [Copyright &y& Elsevier]

Two series of novel heteroleptic derivatives of lanthanides and (η 6 -benzoic acid)tricarbonylchromium (benchrotrenecarboxylic acid) were synthesized and characterized: mononuclear complexes [Ln(BcrCOO)(acac) 2 (H 2 O) 2 ] (Ln = Eu (1), Gd (2), Tb (3a), Dy (4a), Ho (5a)) and 1D-polymeric ones [Ln(BcrCOO)(acac) 2 (H 2 O)] n (Ln = Tb (3b), Dy (4b), Ho (5b), Er (6), Tm (7), Yb (8) and Y (9)), Bcr = (η 6 -C 6 H 5 )Cr(CO) 3 . The molecular and crystal structures of the obtained compounds were determined. Complexes 3a, 4a, 4b, 6 and 8 were found to exhibit SMM properties. Two maxima were observed on χ''(ν) dependencies (LF and HF) for 4a, 4b and 6. For 4a, the anisotropy barriers are Δ eff /k B = 100 K and 118 K in zero dc-field (128 K and 143 K in 2000 Oe field) for the LF (low frequency) and HF (high frequency) signals, respectively. These values are the highest ones for Ln carboxylate complexes. The nature of the appearance of two maxima in the system is discussed.