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Trifluorometylselenolation via C-H activation is barely described in literature. In particular, no such vinylic functionalization has been yet described. Herein, a palladium-catalyzed trifluoromethylselenolation of vinylic C-H bonds is described. The 5-methoxy-8-aminoquinoline has been used as auxiliary directing group to perform this reaction. The reaction gives excellent yields with α-substituted compounds whatever the substituents and a microwave activation can be used to accelerate the reaction. With β-substituted substrates lower yields, but still satisfactory, are obtained. This methodology was also successfully extended to other fluoroalkylselenyl groups., (© 2022 Wiley-VCH GmbH.)

The synthesis of trifluoromethylselenolated aromatic molecules via an auxiliary-assisted, palladium catalyzed, C-H bonds functionalization with trifluoromethyl tolueneselenosulfonate as reagent is described. The mono- or bis-products can be preferentially formed. Some mechanistic investigations were realized to better understand the reaction. This methodology was also extended to fluoroalkylselenyl groups., (© 2021 Wiley-VCH GmbH.)

We report here the synthesis of [Cu 2 (TFA) 4 ( t Bu 2 S) 2 ] (1), [Ag 4 (TFA) 4 ( t Bu 2 S) 4 ] (2) and [AuCl( t Bu 2 S)] (3) (TFA=trifluoroacetate), which decompose in solution medium at ultra-low temperature (e. g., in boiling toluene) to afford phase-pure and highly crystalline Cu 9 S 5 , Ag 2 S and metallic Au nanoparticles, respectively. The low decomposition temperature of these precursors is attributed to the facile decomposition mechanism in the di-tertiary-butyl sulfide ligand. These results are a significant step in the direction of establishing a general low-temperature strategy spanning a range of systems including thermodynamically metastable materials and incorporate them in technologies that are sensitive to the harsh conditions., (© 2021 Wiley-VCH GmbH.)

The straightforward synthesis of a new unsymmetrical hydroxy-tethered N-heterocyclic carbene (NHC) ligand, HL, is presented. The free ligand exhibits an unusual OH-carbene hydrogen-bonding interaction. This OH-carbene motif was used to yield 1) the first tantalum complex displaying both a Fischer- and Schrock-type carbene ligand and 2) a unique NHC-based early/late heterobimetallic complex. More specifically, the protonolysis chemistry between the ligand's hydroxy group and imido-alkyl or alkylidene-alkyl tantalum precursor complexes yielded the rare monometallic tantalum-NHC complexes [Ta(XtBu)(L)(CH 2 tBu) 2 ] (X=N, CH), in which the alkoxy-carbene ligand acts as a chelate. In contrast, HL only binds to rhodium through the NHC unit in [Rh(HL)(cod)Cl] (cod=cycloocta-1,5-diene), the hydroxy pendant arm remaining unbound. This bifunctional ligand scaffold successfully promoted the assembly of rhodium/tantalum heterobimetallic complexes upon either 1) the insertion of [Rh(cod)Cl] 2 into the Ta-NHC bond in [Ta(NtBu)(L)(CH 2 tBu) 2 ] or 2) protonolysis between the free hydroxy group in [Rh(HL)(cod)Cl] and one alkyl group in [Ta(NtBu)(CH 2 tBu) 3 ]., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new dimension for secondary phosphine oxide (SPOs) ligands is described in this article. Demonstrated on original π-allylic nickel structures, these self-assembled complexes trigger catalytic hydrophosphinylation reactions. Addition of a Lewis acid B(C 6 F 5 ) 3 switches the reactivity towards migratory insertion and thus ethylene oligomerization through an unprecedented outer-sphere interaction with the coordinated SPO ligand. NMR experiments and X-ray analyses allowed for the observation of the formation of zwitterionic active species as well as their degradation pathway., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reactions of different silver(I) reagents AgX (X(-) =iodide, trifluoroacetate, triflate) with selenoethers R2 Se (R=Me, tBu) in a variety of solvents were investigated in relation with their use as precursors for Ag2 Se nanomaterials. Different reaction conditions led to different reactivities and afforded either molecular complexes or metal selenide nanoparticles. The reactions leading to in situ formation of the metal selenide nanoparticles were then extended in the presence of commercial TiO2 (P25) to prepare silver selenide-titania nanocomposites with different Ag/Ti ratios. These nanocomposites, well characterized by elemental analysis (Ag, Se), PXRD, TEM, BET, XPS and UV/Vis studies, were investigated as photocatalysts for the degradation of formic acid (FA) solution. The xAg2 Se-TiO2 nanocomposites (x=0.01, 0.13 and 0.25 mol %) exhibited a much higher catalytic activity as compared to P25, which is an established benchmark for the photocatalysis under UV light, and retained a good photocatalytic stability after recycling for several times., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An Ir(I) (NHC)-based hybrid material was prepared using a methodology which allowed the precise positioning and isolation of the Ir centers along the pore channels of a silica framework. The full characterization of the material by solid-state NMR spectroscopy showed that the supported Ir sites were stabilized by the silica surface, as low-coordinated single-site complexes. The material is extremely efficient for the hydrogenation of functional alkenes. The catalytic performance (TOF and TON) is one to two orders of magnitude higher than those of their molecular Ir analogues, and could be related to the prevention of the bimolecular deactivation of Ir complexes observed under homogeneous conditions., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel single-source precursor NaGd(TFA)4 (diglyme) (TFA=trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF4 nanoparticles as an efficient matrix for lanthanide-doped upconverting nanocrystals (NCs) that convert near-infrared radiation into shorter-wavelength UV/visible light. These NCs were then used to prepare well-characterized TiO2@NaGdF4:Yb(3+),Tm(3+) nanocomposites to extend the absorption range of the TiO2 photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO2, the UV part is strongly quenched due to the absorption of TiO2 above its gap at approximately 380 nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A bicyclic ligand platform for iron(II), which allows total control over the complex's magnetic properties in aqueous solution simply by varying one of the six coordination sites of the bispidine ligand, is reported. To achieve this, an efficient synthetic route to an N5 bispidine framework (ligand L4) that features an unsubstituted N-7 site is established. Then, by choosing appropriate N-7-coordinating substituents, the spin state of choice can be imposed on the corresponding ferrous complexes under environmentally relevant conditions in water and near-room temperature. Importantly, the first low-spin and diamagnetic iron(II) chelates in the bispidine series, both in the solid state and in aqueous solution, are reported. The eradication of head-on steric clashes between pendent coordinating arms is at the origin of this success. A new pair of constitutionally similar ferrous coordination compounds of a multidentate ligand system is obtained, which exhibits a distinctly binary (off-on) magnetic relationship. The new synthetic intermediate L4 may be substituted in just one step by any desired pendent arm, thus allowing access to complexes with finely tuned magnetic properties., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

1,1,1-Trimethylhydrazinium iodide ([(CH(3))(3)N-NH(2)]I, 1) was reacted with a silver salt to form the corresponding nitrate ([(CH(3))(3)N-NH(2)][NO(3)], 2), perchlorate ([(CH(3))(3)N-NH(2)][ClO(4)], 3), azide ([(CH(3))(3)N-NH(2)][N(3)], 4), 5-amino-1H-tetrazolate ([(CH(3))(3)N-NH(2)][H(2)N-CN(4)], 5), and sulfate ([(CH(3))(3)N-NH(2)](2)[SO(4)]·2H(2)O, 6·2H(2)O) salts. The metathesis reaction of compound 6·2H(2)O with barium salts led to the formation of the corresponding picrate ([(CH(3))(3)N-NH(2)][(NO(2))(3)Ph-O], 7), dinitramide ([(CH(3))(3)N-NH(2)][N(NO(2))(2)], 8), 5-nitrotetrazolate ([(CH(3))(3)N-NH(2)][O(2)N-CN(4)], 9), and nitroformiate ([(CH(3))(3)N-NH(2)][C(NO(2))(3)], 10) salts. Compounds 1-10 were characterized by elemental analysis, mass spectrometry, infrared/Raman spectroscopy, and multinuclear NMR spectroscopy ((1)H, (13)C, and (15)N). Additionally, compounds 1, 6, and 7 were also characterized by low-temperature X-ray diffraction techniques (XRD). Ba(NH(4))(NT)(3) (NT=5-nitrotetrazole anion) was accidentally obtained during the synthesis of the 5-nitrotetrazole salt 9 and was also characterized by low-temperature XRD. Furthermore, the structure of the [(CH(3))(3)N-NH(2)](+) cation was optimized using the B3LYP method and used to calculate its vibrational frequencies, NBO charges, and electronic energy. Differential scanning calorimetry (DSC) was used to assess the thermal stabilities of salts 2-5 and 7-10, and the sensitivities of the materials towards classical stimuli were estimated by submitting the compounds to standard (BAM) tests. Lastly, we computed the performance parameters (detonation pressures/velocities and specific impulses) and the decomposition gases of compounds 2-5 and 7-10 and those of their oxygen-balanced mixtures with an oxidizer., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

1,1-Dimethylhydrazine can be readily alkylated with bromoacetonitrile to form 1-cyanomethyl-1,1-dimethylhydrazinium bromide ([(CH(3))(2)N(CH(2)CN)NH(2)]Br, 1). The metathesis reaction of compound 1 led to the formation of a new family of energetic salts based on the [(CH(3))(2)N(CH(2)CN)NH(2)](+) cation and nitrate (2), perchlorate (3), azide (4), 5-aminotetrazolate ([H(2)N-CN(4)](-), 5), 5,5'-azobistetrazolate ([N(4)C-N=N-CN(4)](2-), 7), and picrate (8) anions. The new materials were characterized by elemental analysis, mass spectrometry, and (multinuclear) NMR and vibrational (infrared and Raman) spectroscopies. Additionally, the molecular structure of the [(CH(3))(2)N(CH(2)CN)NH(2)](+) cation in compounds 1, 3, and 8 and that of sodium 5,5'-azobistetrazolate octahydrate (NaZT·8H(2)O) were solved by X-ray diffraction techniques. The hydrogen-bonding networks found in the structure of salts 1, 3, 8, and NaZT·8H(2)O are described using graph-set analysis. The melting and decomposition points of the new compounds were determined by differential scanning calorimetry, and insight into their sensitivity towards impact, friction, and electrostatics was gained by submitting the materials to standard tests. Furthermore, we estimated some performance parameters of interest and predicted the decomposition gases formed upon decomposition of salts 2-8 and of mixtures with an oxidizer. The interesting thermal, sensitivity, and performance properties of some of the compounds described in this work make them attractive towards a prospective energetic application., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis and detailed characterization of the new spin crossover (SCO) binuclear complex [{Fe(dpia)(NCS)(2)}(2)(4,4'-bpy)] (1; dpia=di(2-picolyl)amine, 4,4'-bpy = 4,4'-bipyridine) are reported. Variable-temperature magnetic susceptibility measurements show a relatively cooperative two-step spin transition suggesting the occurrence of three spin-state isomers: [HS-HS], [HS-LS], and [LS-LS] (HS: high spin, LS: low spin). A short plateau at 204 K separates the two steps and conforms with about 50% of the complexes having undergone a thermal spin conversion. Routine Mössbauer spectroscopy without applying a magnetic field clearly separates four iron(II) one-center spin states in three [HS-HS], [HS-LS], and [LS-LS] pairs and unambiguously confirms that the spin transition at the plateau temperature goes through the intermediate [HS-LS] state. The single-crystal X-ray structure was solved for three spin isomers at 293, 208, and 120 K. The structural study at the plateau temperature was unable to resolve the HS and LS sites in the [HS-LS] pair and only an average Fe-N bond length was obtained, which suggests that there is an intermediate [HS-LS] phase. The structural analysis at three temperatures revealed a dense three-dimensional network of both intra- and intermolecular interactions. The relative energies of the three spin-state isomers were evaluated by quantum-chemical DFT calculations. Comparison of compound 1 with previously known analogues, as well as the overall analysis of structural data for numerous binuclear complexes, allowed a conclusion to be reached on the crucial role of ligand strain effects in the SCO behavior of binuclear complexes. The suggested intramolecular mechanism explains the different types of SCO observed in binuclear complexes: one-step, two-step, and partial (50%) transitions.

This paper reports the synthesis of a family of mononuclear complexes [Fe(L)]X(2) (X=BF(4), PF(6), ClO(4)) with hexadentate ligands L=Hpy-DAPP ({bis[N-(2-pyridylmethyl)-3-aminopropyl](2-pyridylmethyl)amine}), Hpy-EPPA ({[N-(2-pyridylmethyl)-3-aminopropyl][N-(2-pyridylmethyl)-2-aminoethyl](2-pyridylmethyl)amine}) and Hpy-DEPA ({bis[N-(2-pyridylmethyl)-2-aminoethyl](2-pyridylmethyl)amine}). The systematic change of the length of amino-aliphatic chains in these ligands results in chelate rings of different size: two six-membered rings for Hpy-DAPP, one five- and one six-membered rings for Hpy-EPPA, and two five-membered rings for Hpy-DEPA. The X-ray analysis of three low-spin complexes [Fe(L)](BF(4))(2) revealed similarities in their molecular and crystal structures. The magnetic measurements have shown that all synthesized complexes display spin-crossover behavior. The spin-transition temperature increases upon the change from six-membered to five-membered chelate rings, clearly demonstrating the role of the ligand strain. This effect does not depend on the nature of the counter ion. We discuss the structural features accountable for the strain effect on the spin-transition temperature.

We report here on the synthesis and characterisation of a first iron(II) spin-crossover coordination polymer with the dca spacer ligand, having the formula [Fe(aqin)2(dca)]ClO4.MeOH (aqin=8-aminoquinoline, dca=dicyanamide), which displays a two-step complete spin transition. Variable-temperature magnetic susceptibility measurements and Mössbauer spectroscopy have revealed that the two relatively gradual steps are centred at 215 and 186 K and are separated by an inflection point at about 201 K, at which 50 % of the complex molecules undergo a spin transition. The two steps are related to the existence of two crystallographically inequivalent metal sites, as confirmed by the structural and Mössbauer studies. The crystal structure was resolved at 293 K (HS form) and 130 K (LS form). Both spin-state structures belong to the triclinic P1 space group (Z=2). The complex assumes a linear chain structure, in which the active iron(II) sites are linked to each other by anionic dicyanamide ligands acting as chemical bridges. The Fe-Fe distances through the dca ligand are 8.119(1) and 7.835(1) A in the high-spin and low-spin structures, respectively. The polymeric chains extend along a (1, 0, -1) axis and are packed in sheets, between which the perchlorate anions and methanol molecules are inserted. The complex molecules are linked together by pi-stacking interactions and H-bonding between the H-donor aqin ligands and the perchlorate ions. These structural features provide a basis for cooperative interactions in the crystal lattice. Analysis of the two-step spin-crossover character in this compound suggests that covalent interactions through the spacer ligand do not provide the main mechanism of cooperativity.

The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.5 cm(-1)), which correspond to short and long Cu-Cu distances, respectively, as evidence from the crystal structure [see formulate in text]. It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF-EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero-field splitting parameter D (-0.25+/-0.01 cm(-1)) plus a small rhombic term E (0.025+/-0.001 cm(-1), E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz-type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations.

A new end-to-end azido double-bridged copper(II) complex [Cu(2)L(2)(N(3))2] (1) was synthesized and characterized (L=1,1,1-trifluoro-7-(dimethylamino)-4-methyl-5-aza-3-hepten-2-onato). Despite the rather long Cu-Cu distance (5.105(1) A), the magnetic interaction is ferromagnetic with J= +16 cm(-1) (H=-JS(1)S(2)), a value that has been confirmed by DFT and high-level correlated ab initio calculations. The spin distribution was studied by using the results from polarized neutron diffraction. This is the first such study on an end-to-end system. The experimental spin density was found to be localized mainly on the copper(II) ions, with a small degree of delocalization on the ligand (L) and terminal azido nitrogens. There was zero delocalization on the central nitrogen, in agreement with DFT calculations. Such a picture corresponds to an important contribution of the d(x2-y2) orbital and a small population of the d(z2) orbital, in agreement with our calculations. Based on a correlated wavefunction analysis, the ferromagnetic behavior results from a dominant double spin polarization contribution and vanishingly small ionic forms.