Search

We report the synthesis, structures, and magnetic and luminescence properties of a series of new monoand dinuclear Er3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4-tBu-2,6-(Ph2CH)2C6H2O]3Er(THF) (1), [(C6F5)3CO]3Er(Me3SiOH) (2), [(C6F5)3CO]3Er[(Me3Si)2NH] (3), [(C6F5)3CO]3Er(C6H5CH3) (4), [(C6F5)3CO]3Er(o-Me2NC6H4CH3) (5) and {[Ph(CF3)2CO]2Er(μ²-OC (CF3)2Ph)}2 (6). In compounds 1, 2, and 4, the Er3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er3+ is impacted by the presence of several relatively short Er...F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er3+ characteristic near infrared (NIR) emission associated with the 4I13/2 → 4I15/2 transition with a remarkably long lifetime going up to 73 µs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data. [ABSTRACT FROM AUTHOR]

The catalytic activity of cyclobutadiene rhodium complexes was investigated in various transformations of alkynes. Complexes [Rh(C4Et4)Hal]n (at 1 mol% loading) were found to promote hydrosilylation of 1-octyne selectively giving 1-Z-, 1-E-, or 2-Et3Si-1-octene depending on the nature of the halide ligand and the presence of additional ligand PPh3. Complex [Rh(C4Et4)(p-xylene)]+ (1 mol%) also efficiently catalyzed the polymerization of phenylacetylene. At the same time, we found that various cyclobutadiene rhodium complexes do not catalyze the Diels–Alder reaction, alkyne hydration, and 1,4-addition of boronic acids to cyclohexanone. New complexes [Rh(C4Et4)(PPh3)2]BF4 and [Rh(C4Et4)(C10H8)]PF6 were also synthesized and their structures were established by X-ray diffraction. [ABSTRACT FROM AUTHOR]

A new family of phenanthroline ligands was prepared. Hydrolysis of 4,7-dihalogenated 1,10-phenanthroline-2,9-diamides in acidic media leads to the formation of the corresponding 4,7-oxygenated derivatives. These ligands can exist in different tautomeric forms. The tautomerism of 4,7-oxygenated phenanthroline diamides has been investigated using quantum chemical calculations. The unsymmetrical oxo-hydroxy tautomeric form was proved to be the most energetically advantageous according to the spectral data and X-ray analysis. It was shown that 4,7-difluoro derivatives undergo acid hydrolysis more easily when compared to 4,7-dichloro derivatives. The coordination chemistry of 4,7-oxygenated 1,10-phenanthroline-2,9-diamides toward some lanthanide nitrates was investigated. The structures of Ln-complexes thus formed were studied both in the solid state and in solution (XRD analysis and IR, NMR and UV spectroscopy). It was revealed that 4,7-oxygenated ligands adopt the dihydroxy tautomeric form upon coordination with lanthanide nitrates. [ABSTRACT FROM AUTHOR]

The rhodium complex [(C5H2tBu2CH2tBu)RhCl2]2 with an asymmetric cyclopentadienyl ligand was prepared in 95% yield by the reaction of [(cod)RhCl]2 with tert-butylacetylene in the presence of AlCl3. A similar reaction in the presence of InBr3 gave the cationic fulvene complex [(C5H2tBu2 = CHtBu)Rh(cod)]InBr4 (70%), which can add alcohols ROH and produce more bulky catalysts [(C5H2tBu2CH(OR)tBu)RhCl2]2. The enantiomers of these planar-chiral complexes were separated by thin-layer chromatography in the presence of L-phenylglycinol. The complexes catalyze the reactions of arylhydroxamates with alkenes giving dihydroisoquinolones in excellent yields (80–90%), but with moderate enantioselectivity (typically 20–50% ee). [ABSTRACT FROM AUTHOR]

Piperazine (Pipz) is widely used as a building block for the self-assembly of supramolecular hydrogen-bonded crystalline networks. Here, piperazine-1,4-diol (PipzDiol) has been suggested as an analog of piperazine with an extended H-bond donor geometry. A convenient synthesis of PipzDiol has been developed and the compound has been fully characterized. Structural and stereodynamic studies showed that PipzDiol exists in solution as a dynamic mixture of conformers/invertomers. The formation of co-crystals with acids is accompanied by preferable selection of one stereoisomeric form depending on the nature of the co-former. Piperazine and PipzDiol were found to form distinct supramolecular H-bonded networks with topologically different H-bonded motifs. In crystalline adducts with sulfuric, oxalic, and para-aminobenzoic acids, piperazine forms 3D H-bonded networks, while 2D layers are assembled with PipzDiol. [ABSTRACT FROM AUTHOR]

We report the synthesis, crystal structures, and magnetic and theoretical investigations of five erbium complexes based on halogenated ligands with the respective formulas trans-[Er(L1)3(THF)2] (1), trans-[Er(L2)3(Ph3PO)2] (2), fac-[Er(L3)3(THF)3] (3), fac-[Er(L4)3(Ph3PO)3] (4), and [Er(L5)3] (5) (L1 = OCPh2(CF2Cl), L2 = OCPh(CF3)2, L3 = OCH(C6F5)2, L4 = OCHMe(C6F5), L5 = 1,8-dibromo-3,6-di-tert-butylcarbazol-9-ide, THF = tetrahydrofuran). Modulation of the experimental conditions allows controlling the coordination geometry of the resulting complexes. While 1 and 2 adopt a trigonal bipyramidal geometry, 3 and 4 exhibit a distorted octahedral arrangement. In contrast, 5 exhibits a triangular coordination geometry. Magnetic investigations in line with theoretical calculations reveal that only the three-coordinated complex 5 exhibits a zero-field slow relaxation of the magnetization, while compound 1 demonstrates field-induced relaxation dynamics. [ABSTRACT FROM AUTHOR]

A series of new half-sandwich bis(alkyl) rare-earth metal complexes coordinated by a sterically demanding 1,3,6,8-tetra-tert-butyl-carbazol-9-yl ligand [tBu4Carb]La(CH2C6H5)2(THF) (1-La), [tBu4Carb]Ln(o-NMe2C6H4CH2)2 (Ln = Sc (2-Sc), Y (2-Y), La (2-La), [tBu4Carb]Ln(CH2SiMe3)2(THF) (Ln = Sc (3-Sc), Y (3-Y)), were synthesized. 1-La, 2-La, and 2-Y were prepared by an alkane elimination protocol, while 2-Sc, 3-Sc, and 3-Y became accessible only when salt metathesis reactions of tBu4CarbK with R2Ln(THF)n+[BPh4]− were employed. X-ray analysis revealed that in all complexes the carbazolyl ligand exhibits π-coordination with metal ions. 2-Sc and 3-Sc when activated with [Ph3C][B(C6F5)4] demonstrate excellent activity in α-olefin (octene-1, nonene-1, decene-1 and 1,1-diphenyl-but-1-ene) polymerization. When H2 was used as a chain transfer agent (1 bar, rt) in the presence of 3-Sc/[Ph3C][B(C6F5)4] or 2-Y, 2-La olefin hydrogenation occurred with quantitative conversion. [ABSTRACT FROM AUTHOR]

Asymmetric cyclopropanation of alkenes by aryldiazoacetates was achieved using the readily-available racemic (diene)rhodium complex in combination with the chiral oxazoline-phenol ligand, which acts as the chiral poison and selectively inhibits one of the enantiomers of the catalyst. This approach eliminates a common problematic step of the synthesis of chiral catalysts. [ABSTRACT FROM AUTHOR]

4,6,10-Trihydroxy-1,4,6,10-tetraazaadamantane (TAAD) has been shown to form a stable Fe(IV) complex having a diamantane cage structure, in which the metal center is coordinated by three oxygen atoms of the deprotonated ligand. The complex was characterized by X-ray diffraction analysis, HRMS, NMR, FT-IR, Mössbauer spectroscopy and DFT calculations, which supported the d4 configuration of iron. The Fe(IV)-TAAD complex showed excellent performance in dioxygen activation under mild conditions serving as a mimetic of the thiol oxidase enzyme. The nucleophilicity of the bridgehead nitrogen atom in TAAD provides a straightforward way for the conjugation of Fe(IV)-TAAD complexes to various functional molecules. Using this approach, steroidal and peptide molecules having an iron(IV) label have been prepared for the first time. In addition, the Fe(IV)-TAAD complex was covalently bound to a polystyrene matrix and the resulting material was shown to serve as a heterogeneous catalyst for aerobic oxidation of thiols to disulfides. [ABSTRACT FROM AUTHOR]

The catalytic activity in amine-borane dehydrogenation is shown for the first time for Ln(II) species using complexes [{(p-tBu-C6H4)2CH}2M·L] (M = Yb, Sm, L = (DME)2, TMEDA). The protonation of M(II)–C bonds with HNR1R2BH3 affords amidoborane complexes [M(NR1R2BH3)2L], which under excess HNMe2BH3 transform to [NMe2BH2NMe2BH3]− derivatives, both serving as the dehydrocoupling intermediates. [ABSTRACT FROM AUTHOR]

A recently introduced concept of reduced paramagnetic shifts (RPS) in NMR spectroscopy is applied here to a series of paramagnetic complexes with different metal ions, such as iron(II), iron(III) and cobalt(II), in different coordination environments of N-donor ligands, including a unique trigonal-prismatic geometry that is behind some record single-molecule magnet behaviours. A simple, almost visual analysis of the chemical shifts as a function of temperature, which is at the core of this approach, allows for a correct signal assignment and evaluation of the anisotropy of the magnetic susceptibility, the key indicator of a good single molecule magnet, that often cannot be done using traditional techniques rooted in quantum chemistry and NMR spectroscopy. The proposed approach thus emerged as a powerful alternative in deciphering the NMR spectra of paramagnetic compounds for applications in data processing and storage, magnetic resonance imaging and structural biology. [ABSTRACT FROM AUTHOR]

We report the synthesis, crystal structures and magnetic investigations of four octahedral dysprosium complexes based on silanolate or stannanolate ligands of respective formula cis-[Dy(OSiPh3)2(THF)4][BPh4]·THF·C6H6 (1), cis-[Dy(OSnPh3)2(THF)4][BPh4]·THF·C6H6·C6H14 (2), fac-[Dy(OSiPh3)3(THF)3]·THF (3) and fac-[Dy(OSiPh3)3(bipy)(THF)]·THF (4) (where THF = tetrahydrofuran, Ph = phenyl, bipy = 2,2′-bipyridine). Whereas complexes 1–3 exhibit a field-induced slow relaxation of the magnetization, 4 is a zero-field single-molecule magnet, which could be rationalized by the introduction of the bidentate bipy ligand providing a more important linearity of the (Si)O–Dy–O(Si) angle through distortion of the coordination sphere. [ABSTRACT FROM AUTHOR]

Two series of heterometallic LnIII–CuII compounds containing a butterfly-like tetranuclear metal core were synthesized and characterized by X-ray diffraction and magnetometry. The structures of the new compounds were shown to depend on the nature of the hydroxide used for the synthesis. The reactions of copper(II) and lanthanide(III) salts with Hpiv (Hpiv is trimethylacetic acid) and LiOH in a MeCN–EtOH mixture afford the molecular complexes [Ln2Cu2(μ3-OH)2(piv)8(H2O)4]·4EtOH (1Ln, Ln = Gd, Tb, Dy, Ho, Yb), whereas the similar reactions using NaOH instead of LiOH give the 1D coordination polymers [Na2Ln2Cu2(μ3-OH)2(piv)10(EtOH)2]·EtOH (2Ln, Ln = Gd, Tb, Dy, Ho, Yb). According to ac susceptibility measurements, the DyIII–CuII compounds (1Dy and 2Dy) exhibit slow relaxation of magnetization indicative of single-molecule magnet (SMM) behavior. In the series of YbIII–CuII compounds, only complex 2Yb shows frequency-dependent out-of-phase ac susceptibility signals. This is the first reported example of carboxylate-based YbIII–CuII compound displaying slow magnetic relaxation. [ABSTRACT FROM AUTHOR]

We report the synthesis and structures of three luminescent dysprosium(III) complexes based on fluorinated alkoxide ligands of formulas [Dy(L1)2(THF)4][BPh4]·0.5THF (1), [Dy(L2)2(THF)5][BPh4]·2.5THF (2) and [Dy(L3)2(THF)5][BPh4]·2THF (3) (L1 = (CF3)3CO−, L2 = C6F5C6F4O−, L3 = C6F5C(CH3)O−). Despite the different dysprosium ion geometries (octahedral vs. distorted pentagonal bipyramidal), these systems exhibit a single-molecule magnet (SMM) behavior, but with distinct relaxation dynamics. Moreover, a typical dysprosium-based luminescence is observed for the three complexes, which make them bifunctional magneto-luminescent SMMs. Remarkably, complex 3 exhibits a high anisotropy barrier of 1469 cm−1 and a blocking temperature of 22 K, making it one of the most performant alkoxide-based SMMs with the highest blocking temperature for a luminescent SMM. [ABSTRACT FROM AUTHOR]

Thirteen new metallacarborane complexes of rhodium and iridium with covalently bound cage carbon atoms were synthesized and their thermal stability was investigated. Two iridium complexes undergo a polyhedral rearrangement with the formation of more than one isomer. The structures of the new isomers were determined by a single crystal X-ray diffraction analysis and 11B{1H}–11B{1H} COSY NMR. A full isomerization scheme of the less thermally stable complex was proposed based on DFT calculations. According to this mechanism sequential downhill and uphill bifurcations arise in the reaction pathway. Each bifurcation is responsible for a new product formation. [ABSTRACT FROM AUTHOR]

NiBr2 reacts with 3-hexyne in the presence of Mg and EtOH to give the cyclobutadiene bromide complex [(C4Et4)NiBr2]2, which serves as a general precursor for various cyclobutadiene nickel compounds. In particular, complexes with 2-electron ligands (C4Et4)Ni(L)Br2 (L = PPh3, P(OMe)3, pyridine), complexes with bidentate ligands [(C4Et4)Ni(L2)Br]PF6 (L2 = bipyridine, phenanthroline), and nickelacarborane (C4Et4)NiC2B9H11 were obtained from [(C4Et4)NiBr2]2 in 70–95% yields. The reactions of [(C4Et4)NiBr2]2 with an excess of strong ligands, such as tBuNC or dppe, led to the displacement of cyclobutadiene. The structures of the five compounds have been established by X-ray diffraction analysis. The previously reported data on cyclobutadiene nickel complexes have been also reviewed. [ABSTRACT FROM AUTHOR]

Here we report a combined use of THz-EPR and NMR spectroscopy for obtaining a detailed electronic structure of a long-known high-spin complex, cobalt(ii) bis[tris(pyrazolyl)borate]. The lowest inter-Kramers transition was directly measured by THz-EPR spectroscopy, while the energies of higher Kramers doublets were estimated by a recently proposed NMR-based approach. Together, they produced magnetic parameters for a full model that explicitly includes spin–orbit coupling. This approach is applicable to all transition metal ions for which the spin–orbit coupling cannot be treated perturbatively. [ABSTRACT FROM AUTHOR]

The first synthesized and X-ray structurally characterized “classical” iron(i) dioximate showed an unrivaled stability towards strong acids, thus calling for a reassessment of the origins of the electrocatalytic activity of similar low-valent cobalt and iron cage complexes with electron-withdrawing ribbed substituents, shown previously to be effective electrocatalysts of the HER. [ABSTRACT FROM AUTHOR]

New antimony-capped iron and nickel(ii) tris-pyridineoximates with a labile triethylantimony cross-linking group were obtained by template condensation of 2-acetylpyridinoxime with triethylantimony(v) dibromide on the corresponding metal ion as a matrix. They easily undergo transmetallation (capping group exchange) with Lewis-acidic zirconium and hafnium(iv) phthalocyaninates (Pc) to give binuclear MPc-capped tris-pyridineoximates. The obtained hybrid complexes and their precursors were thoroughly characterized (among others, by single-crystal X-ray diffraction), and their redox properties were studied by cyclic and differential pulse voltammetry. [ABSTRACT FROM AUTHOR]

An atom-economical methodology for the synthesis of sterically hindered tertiary amines was developed, which is based on complementary Rh- and Ru-catalyzed direct reductive amination of ketones with primary and secondary amines using carbon monoxide as a deoxygenating agent. [ABSTRACT FROM AUTHOR]

In pursuit of a new and simple approach to complex organometallic systems, the possibility of formation of a palladium–carbon bond in the solid state via direct cyclopalladation has been studied toward several S,C,S′-pincer ligands with thione sulfur donors of different nature. It is found that mixtures of the ligand and PdCl2(NCPh)2 obtained by the manual grinding of reactants in a mortar efficiently undergo solid-phase cyclometalation upon heating in open test tubes without the addition of a solvent to afford the desired pincer-type products in high yields. In the case of the most active bis(thiocarbamoyl) ligand, solid-phase cyclopalladation proceeds even at room temperature. For the challenging bis(thiophosphoryl) derivative, the preformed non-metallated complexes can be successfully used as a starting material to essentially enhance the yield of the desired pincer complex compared to the conventional synthesis in solution. The solid-phase transformation is followed by IR spectroscopy and SEM analysis. The results obtained show that the suggested solid-phase methodology can serve as a powerful alternative to conventional synthesis of pincer complexes in solution. [ABSTRACT FROM AUTHOR]

Chemical bonding peculiarities in the crystalline dihydrate of sodium iodide were examined by means of Bader's "Atoms in Molecule" theory and the energies of cation-anion, cation-water and anion-water contacts were estimated on the basis of the experimental data that were shown to provide insight into the tendency of NaI to form co-crystals with the majority of solvents. [ABSTRACT FROM AUTHOR]

An unexpected mechanism of halogen bonding that cannot be rationalized within the accepted σ-hole model was found in the co-crystal of N-methylpyrazine iodide with molecular iodine viathe topological analysis of the electron density distribution derived from the high-resolution X-ray diffraction data. [ABSTRACT FROM AUTHOR]

Topological analysis of the experimental electron density distribution functions for two polymorphs of paracetamol showed that strong H-bonds are responsible for the higher stability of crystal phase I, weak interactions for the higher density of phase II. This made it possible to finally resolve the contradiction between the relative stabilities and the densities of the two paracetamol polymorphs. [ABSTRACT FROM AUTHOR]

Heating tert -butyl-tetraline with [( p -cymene)RuCl 2 ] 2 produces the racemic complex [(arene)RuCl 2 ] 2 , which can be separated into enantiomers by chromatography of its diastereomeric adducts with chiral phosphine ligand. The resolved chiral complex catalyzes C-H activation of N -methoxy-benzamides and their annulation with N -vinyl-pivaloyl amide giving dihydroisoquinolones in 50-80% yields and with 40-80% enantiomeric excess.

We report the synthesis, structures, and magnetic and luminescence properties of a series of new mono- and dinuclear Er 3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4- t Bu-2,6-(Ph 2 CH) 2 C 6 H 2 O] 3 Er(THF) (1), [(C 6 F 5 ) 3 CO] 3 Er(Me 3 SiOH) (2), [(C 6 F 5 ) 3 CO] 3 Er[(Me 3 Si) 2 NH] (3), [(C 6 F 5 ) 3 CO] 3 Er(C 6 H 5 CH 3 ) (4), [(C 6 F 5 ) 3 CO] 3 Er( o -Me 2 NC 6 H 4 CH 3 ) (5) and {[Ph(CF 3 ) 2 CO] 2 Er(μ 2 -OC(CF 3 ) 2 Ph)} 2 (6). In compounds 1, 2, and 4, the Er 3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er 3+ is impacted by the presence of several relatively short Er⋯F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er 3+ characteristic near infrared (NIR) emission associated with the 4 I 13/2 → 4 I 15/2 transition with a remarkably long lifetime going up to 73 μs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data.

A new family of phenanthroline ligands was prepared. Hydrolysis of 4,7-dihalogenated 1,10-phenanthroline-2,9-diamides in acidic media leads to the formation of the corresponding 4,7-oxygenated derivatives. These ligands can exist in different tautomeric forms. The tautomerism of 4,7-oxygenated phenanthroline diamides has been investigated using quantum chemical calculations. The unsymmetrical oxo-hydroxy tautomeric form was proved to be the most energetically advantageous according to the spectral data and X-ray analysis. It was shown that 4,7-difluoro derivatives undergo acid hydrolysis more easily when compared to 4,7-dichloro derivatives. The coordination chemistry of 4,7-oxygenated 1,10-phenanthroline-2,9-diamides toward some lanthanide nitrates was investigated. The structures of Ln-complexes thus formed were studied both in the solid state and in solution (XRD analysis and IR, NMR and UV spectroscopy). It was revealed that 4,7-oxygenated ligands adopt the dihydroxy tautomeric form upon coordination with lanthanide nitrates.

A series of new half-sandwich bis(alkyl) rare-earth metal complexes coordinated by a sterically demanding 1,3,6,8-tetra- tert -butyl-carbazol-9-yl ligand [ t Bu 4 Carb]La(CH 2 C 6 H 5 ) 2 (THF) (1-La), [ t Bu 4 Carb]Ln( o -NMe 2 C 6 H 4 CH 2 ) 2 (Ln = Sc (2-Sc), Y (2-Y), La (2-La), [ t Bu 4 Carb]Ln(CH 2 SiMe 3 ) 2 (THF) (Ln = Sc (3-Sc), Y (3-Y)), were synthesized. 1-La, 2-La, and 2-Y were prepared by an alkane elimination protocol, while 2-Sc, 3-Sc, and 3-Y became accessible only when salt metathesis reactions of t Bu 4 CarbK with R 2 Ln(THF) n + [BPh 4 ] - were employed. X-ray analysis revealed that in all complexes the carbazolyl ligand exhibits π-coordination with metal ions. 2-Sc and 3-Sc when activated with [Ph 3 C][B(C 6 F 5 ) 4 ] demonstrate excellent activity in α-olefin (octene-1, nonene-1, decene-1 and 1,1-diphenyl-but-1-ene) polymerization. When H 2 was used as a chain transfer agent (1 bar, rt) in the presence of 3-Sc/[Ph 3 C][B(C 6 F 5 ) 4 ] or 2-Y, 2-La olefin hydrogenation occurred with quantitative conversion.

4,6,10-Trihydroxy-1,4,6,10-tetraazaadamantane (TAAD) has been shown to form a stable Fe(IV) complex having a diamantane cage structure, in which the metal center is coordinated by three oxygen atoms of the deprotonated ligand. The complex was characterized by X-ray diffraction analysis, HRMS, NMR, FT-IR, Mössbauer spectroscopy and DFT calculations, which supported the d 4 configuration of iron. The Fe(IV)-TAAD complex showed excellent performance in dioxygen activation under mild conditions serving as a mimetic of the thiol oxidase enzyme. The nucleophilicity of the bridgehead nitrogen atom in TAAD provides a straightforward way for the conjugation of Fe(IV)-TAAD complexes to various functional molecules. Using this approach, steroidal and peptide molecules having an iron(IV) label have been prepared for the first time. In addition, the Fe(IV)-TAAD complex was covalently bound to a polystyrene matrix and the resulting material was shown to serve as a heterogeneous catalyst for aerobic oxidation of thiols to disulfides.

Two series of heterometallic Ln III -Cu II compounds containing a butterfly-like tetranuclear metal core were synthesized and characterized by X-ray diffraction and magnetometry. The structures of the new compounds were shown to depend on the nature of the hydroxide used for the synthesis. The reactions of copper(II) and lanthanide(III) salts with Hpiv (Hpiv is trimethylacetic acid) and LiOH in a MeCN-EtOH mixture afford the molecular complexes [Ln 2 Cu 2 (μ 3 -OH) 2 (piv) 8 (H 2 O) 4 ]·4EtOH (1Ln, Ln = Gd, Tb, Dy, Ho, Yb), whereas the similar reactions using NaOH instead of LiOH give the 1D coordination polymers [Na 2 Ln 2 Cu 2 (μ 3 -OH) 2 (piv) 10 (EtOH) 2 ]·EtOH (2Ln, Ln = Gd, Tb, Dy, Ho, Yb). According to ac susceptibility measurements, the Dy III -Cu II compounds (1Dy and 2Dy) exhibit slow relaxation of magnetization indicative of single-molecule magnet (SMM) behavior. In the series of Yb III -Cu II compounds, only complex 2Yb shows frequency-dependent out-of-phase ac susceptibility signals. This is the first reported example of carboxylate-based Yb III -Cu II compound displaying slow magnetic relaxation.

We report the synthesis and structures of three luminescent dysprosium(iii) complexes based on fluorinated alkoxide ligands of formulas [Dy(L1)2(THF)4][BPh4]·0.5THF (1), [Dy(L2)2(THF)5][BPh4]·2.5THF (2) and [Dy(L3)2(THF)5][BPh4]·2THF (3) (L1 = (CF3)3CO-, L2 = C6F5C6F4O-, L3 = C6F5C(CH3)O-). Despite the different dysprosium ion geometries (octahedral vs. distorted pentagonal bipyramidal), these systems exhibit a single-molecule magnet (SMM) behavior, but with distinct relaxation dynamics. Moreover, a typical dysprosium-based luminescence is observed for the three complexes, which make them bifunctional magneto-luminescent SMMs. Remarkably, complex 3 exhibits a high anisotropy barrier of 1469 cm-1 and a blocking temperature of 22 K, making it one of the most performant alkoxide-based SMMs with the highest blocking temperature for a luminescent SMM.

Thirteen new metallacarborane complexes of rhodium and iridium with covalently bound cage carbon atoms were synthesized and their thermal stability was investigated. Two iridium complexes undergo a polyhedral rearrangement with the formation of more than one isomer. The structures of the new isomers were determined by a single crystal X-ray diffraction analysis and 11 B{ 1 H}- 11 B{ 1 H} COSY NMR. A full isomerization scheme of the less thermally stable complex was proposed based on DFT calculations. According to this mechanism sequential downhill and uphill bifurcations arise in the reaction pathway. Each bifurcation is responsible for a new product formation.

NiBr2 reacts with 3-hexyne in the presence of Mg and EtOH to give the cyclobutadiene bromide complex [(C4Et4)NiBr2]2, which serves as a general precursor for various cyclobutadiene nickel compounds. In particular, complexes with 2-electron ligands (C4Et4)Ni(L)Br2 (L = PPh3, P(OMe)3, pyridine), complexes with bidentate ligands [(C4Et4)Ni(L2)Br]PF6 (L2 = bipyridine, phenanthroline), and nickelacarborane (C4Et4)NiC2B9H11 were obtained from [(C4Et4)NiBr2]2 in 70-95% yields. The reactions of [(C4Et4)NiBr2]2 with an excess of strong ligands, such as tBuNC or dppe, led to the displacement of cyclobutadiene. The structures of the five compounds have been established by X-ray diffraction analysis. The previously reported data on cyclobutadiene nickel complexes have been also reviewed.

An efficient method for the CF3-carbenoid C-H functionalization of 6-arylpurines has been developed. This protocol uses readily available methyl 3,3,3-trifluoro-2-diazopropionate as a cross-coupling partner and proceeds smoothly under chelation-controlled Rh(iii) catalysis. The reactions provide the corresponding carbene insertion products with high regioselectivity within a few hours and allow the introduction of both the CF3 and carboxylate functions into biologically important purine molecules including nucleoside derivatives.