Rodrigo González-Prieto

Open‐shell vanadium organometallic species with unprecedented structures and reactivity patterns are reported. Divanadium(III) complexes with four symmetric pyramidal bridging methyl or parent amido ligands, [{VCp*(µ‐X) ₂ } ₂ ] (Cp* = η ⁵ ‐C ₅ Me ₅ , X = CH ₃ , NH ₂ ), exhibit an open‐shell singlet ground state with a single V─V bond and a relatively small singlet‒triplet energy gap, according to theoretical calculations and magnetic measurements. The thermal decomposition of the tetramethyl species in hexane at 160°C cleanly affords the tetranuclear cube‐type methylidene complex [{VCp*(µ ₃ ‐CH ₂ )} ₄ ] with the release of methane. In contrast, the analogous thermolysis in benzene or toluene allows the isolation of trovacene derivatives with η ⁷ ‐cycloheptatrienyl ligands [VCp*(η ⁷ ‐C ₇ H ₆ R)] (R = H, Me), via a formal insertion of a CH fragment into the six‐membered aromatic ring of the solvent. A similar ring expansion is observed in the thermolysis of the tetramethyl compound in naphthalene (C ₁₀ H ₈ ) solution, yielding a trovacene derivative [VCp*(η ⁷ ‐C ₁₁ H ₉ )] with the slipped triple‐decker sandwich vanadium(I) species [(VCp*) ₂ (µ‐η ⁶ :η ⁶ ‐C ₁₀ H ₈ )] as an isolated byproduct. Overall, the thermal decomposition of [{VCp*(µ‐CH ₃ ) ₂ } ₂ ] in benzenic solvents leads to variable mixtures of methylidene [{VCp*(µ ₃ ‐CH ₂ )} ₄ ] and trovacene complexes depending on arene substituents.

The self-assembly of paramagnetic molecular units into higher-order architectures remains a largely unexplored strategy for creating functional magnetic materials. Here we report the formation of supramolecular polymers from a metal-metal bonded diruthenium monomer. Variable-concentration NMR studies, including DOSY, demonstrate the chloride-driven self-assembly of monomeric species into linear aggregates in solution. Remarkably, magnetic measurements reveal that the paramagnetic character of the monomer is successfully transferred to the supramolecular polymer, giving rise to a magnetically active material. The comparison between monomeric and aggregated states shows that supramolecular organization modulates the magnetic properties through intermolecular interactions. This work establishes metal-metal-bonded diruthenium units as versatile building blocks for designing paramagnetic supramolecular material with emergent magnetic behavior

Layered double hydroxides (LDH) based on transition metals are highly flexible in tailoring their dimensionality, lattice, and electronic structures, making them promising candidates as multifunctional 2D materials for the development of clean energy technologies and boosting the use of hydrogen as an energy vector. In this paper, strategic anion substitution in cobalt LDH is an appealing strategy to produce a material with two‐fold functionality, electrochemical and magnetocaloric response, offering a sustainable alternative to existing electrocatalysts and cryogenic refrigerants. It is unambiguously demonstrated that (poly)oxomolybdate‐based specimens interleave in Co LDH nanosheets up to a Co:Mo = 1:0.4 ratio, leading to an interstratified material. This intercalation greatly benefits the kinetics of the oxygen evolution reaction for H ₂ production, boosting the catalytic sites due to the expansion of the interlayer space, induced by the bulky molybdates which also partially modify the Co oxidation state of αCo(OH) ₂ nanolayers, favoring charge transfer. In parallel, the interleaved Mo species strengthen superexchange interactions compared with pristine α‐Co(OH) ₂ , effectively adjusting the operating temperature toward the liquid hydrogen range (2030 K). This specific temperature range allows to fill a critical gap in magnetocaloric materials, as few systems can simultaneously achieve both large magnetic entropy changes and structural stability.

The synthesis, characterization and structural determination of four complexes with formula (PPh4)n[Rh2(µ–O2CPh)4Au(CN)2]n (1) and Kn[Rh2(µ–O2CR)4M(CN)2]n (M = Au, R = OEt (2), OMe (3); M = Ag, R = OMe (4)) are described. In all cases, the [CN-M-CN]– (M = Au, Ag) group is bridging the axial positions of the dirhodium units giving one-dimensional chains. The packing of the chains in the solid state depends on the nature of the carboxylate group of the dimetallic unit, the counterion present in the complex and the metal itself. The most striking change is observed in the Kn[Rh2(μ-O2CCH2OMe)4Au(CN)2]n complex (3) where the chains are positioned perpendicular to each other with an Au···Au interchain distance of 2.963 Å. The emission studies of this complex upon excitation at 350 nm show a clear broad emission band centered at 430 nm, while no luminescence is observed for the other compounds. The appearance of emission properties only in the case of complex 3 can be explained by its short aurophilic inter-actions.

Synthesis of [Ru₂Cl(Dp-FPhF)_x(O₂CCH₃)_4−x] compounds and the study of how electronic density variation of the Ru₂⁵⁺ core affects their physicochemical properties.

Conventional heating and solvothermal synthetic methods (with or without microwave activation) have been used to study the reaction of o-, m- and p-methoxybenzoic acid with [Ru₂Cl(μ-O₂CMe)₄]. The tetrasubstituted series [Ru₂Cl(µ-O₂CC₆H₄-R)₄], with R = o-OMe, m-OMe and p-OMe, has been prepared by the three procedures. Depending on the synthetic method and the experimental conditions, three compounds have been isolated (1a, 1b, 1c) with the o-methoxybenzoate ligand. However, with the m- and p-methoxybenzoate ligands, only the complexes 2 and 3 have been obtained, respectively. Compound 1a, with stoichiometry [Ru₂Cl(µ-O₂CC₆H₄-o-OMe)₄]_n, shows a polymeric structure with the chloride ions bridging the diruthenium units to form linear chains. Compounds 2 and 3, with the same stoichiometry, predictably form zig-zag chains in accordance with their insolubility and their magnetic measurements. Compound 1b, [Ru₂Cl(µ-O₂CC₆H₄-o-OMe)₄(EtOH)], is a discrete molecular species with a chloride ion and one ethanol molecule occupying the axial positions of the dimetallic unit. Compound 1c is a cation-anion complex, [Ru₂(µ-O₂CC₆H₄-o-OMe)₄(MeOH)₂][Ru₂Cl₂(µ-O₂CC₆H₄-o-OMe)₄]. The cationic complex has two solvent molecules at the axial positions whereas the anionic complex has two chloride ligands at these positions. Complexes have been characterized by elemental analyses, mass spectrometry and IR and UV-vis-NIR spectroscopies. A magnetic study of complexes 1a, 1b, 2 and 3 have also been carried out. The crystal structure of compounds 1b and 1c have been solved by single X-ray crystal methods.

Two new dinuclear nickel(II) complexes, [(H₂O)Ni(N₃)(L¹)(μ_1,1-N₃)Ni(L¹)] and [(H₂O)Ni(N₃)(L²)(μ_1,1-N₃)Ni(L²)]·MeOH, derived from two isomeric Schiff base ligands, HL¹ [2-{(2-(ethylamino)ethylimino)methyl}-6-ethoxyphenol] and HL² [2-{(2-(dimethylamino)ethylimino)methyl}-6-ethoxy-phenol], have been synthesized and characterized. Variable temperature (2–300 K) magnetic susceptibility measurements indicate the presence of moderate ferromagnetic exchange coupling between nickel(II) centers. In each complex, antiferromagnetic exchange takes place through the phenoxido bridge and ferromagnetic through the μ_1,1-azido bridge. The competitive interactions therefore reduce the overall magnetic coupling. In a theoretical complex, where the bridging azido ligand has been eliminated and the rest of the geometry is kept frozen, the magnetic coupling becomes antiferromagnetic which suggests that the ferromagnetic exchange occurs via the μ_1,1-azido bridge. Mulliken population analysis and spin density plots clearly show that the spin distributed spherically in the Ni centers is due to the presence of one unpaired electron in both the and orbitals. The shape of the spin density at the bridging O-atom and azide evidences the participation of their p orbitals in the magnetic coupling. The SOMO is basically constituted by the orbital of one nickel(II) center with the participation of the azide π-system. The SOMO−1 is constituted by the orbital of the other nickel(II), an oxygen atom and the azide π-system.

In this article, we report on the synthesis and characterization of the tetracarboxylatodirhodium(II) complexes [Rh₂(μ–O₂CCH₂OMe)₄(THF)₂] (1) and [Rh₂(μ–O₂CC₆H₄–p–CMe₃)₄(OH₂)₂] (2) by metathesis reaction of [Rh₂(μ–O₂CMe)₄] with the corresponding ligand acting also as the reaction solvent. The reaction of the corresponding tetracarboxylato precursor, [Rh₂(μ–O₂CR)₄], with PPh₄[Au(CN)₂] at room temperature, yielded the one-dimensional polymers (PPh₄)_n[Rh₂(μ–O₂CR)₄Au(CN)₂]_n (R = Me (3), CH₂OMe (4), CH₂OEt (5)) and the non-polymeric compounds (PPh₄)₂{Rh₂(μ–O₂CR)₄[Au(CN)₂]₂} (R = CMe₃ (6), C₆H₄–p–CMe₃ (7)). The structural characterization of 1, 3·2CH₂Cl₂, 4·3CH₂Cl₂, 5, 6, and 7·2OCMe₂ is also provided with a detailed description of their crystal structures and intermolecular interactions. The polymeric compounds 3·2CH₂Cl₂, 4·3CH₂Cl₂, and 5 show wavy chains with Rh–Au–Rh and Rh–N–C angles in the ranges 177.18°–178.69° and 163.0°–170.4°, respectively. A comparative study with related rhodium-silver complexes previously reported indicates no significant influence of the gold or silver atoms in the solid-state arrangement of these kinds of complexes.

In this article, we describe the preparation of anionic heteronuclear one-dimensional coordination polymers made by dirhodium paddlewheels and tetracyanido-metallatate building blocks. A series of complexes of (PPh₄)_2n[{Rh₂(µ-O₂CCH₃)₄}{M(CN)₄}]_n (M = Ni (1), Pd (2), Pt (3)) formulae were obtained by reaction of [Rh₂(μ-O₂CCH₃)₄] with (PPh₄)₂[M(CN)₄] in a 1:1 or 2:1 ratio. Crystals of 1−3 suitable for single crystal X-ray diffraction were grown by slow diffusion of a dichloromethane solution of the dirhodium complex into a chloroform solution of the corresponding tetracyanido–metallatate salt. Compounds 1 and 2 are isostructural and crystallize in the triclinic P-1 space group, while compound 3 crystallizes in the monoclinic P2₁/n space group. A detailed description of the structures is presented, including the analysis of the packing of anionic chains and PPh₄⁺ cations.