Search

Tris(pyrazolyl)methane (tpm), 2,2,2-tris(pyrazolyl)ethanol (tpmOH) and its esterification derivatives with ibuprofen and flurbiprofen (tpmIBU and tpmFLU) were used as ligands to obtain complexes of the type [Fe(tpmX)2]Cl2 (1–4). The tpmIBU and tpmFLU ligands and corresponding complexes 3 and 4 were characterized by IR and multinuclear NMR spectroscopy, and the structure of tpmIBU was elucidated by single crystal X-ray diffraction. Complexes 1–4 were also assessed for their behaviour in aqueous media (solubility in D2O, octanol/water partition coefficient, stability in physiological-like conditions). The antiproliferative activity of ligands and complexes was determined on A2780, A2780cis and A549 cancer cell lines and the non-cancerous HEK 293T and BJ cell lines. The ligands and complexes were investigated for their ability to inhibit COX-2 (cyclooxygenase) and HNE (4-hydroxynonenal) enzymes. Complexes 3 and 4 exhibited cytotoxicity that may be attributed predominantly to their bioactive fragments, while DNA binding and enhancement of ROS production do not appear to play any significant role. [ABSTRACT FROM AUTHOR]

We conducted a joint synthetic, spectroscopic and computational study to explore the reactivity towards cyanide (from Bu4NCN) of a series of dinuclear complexes based on the M2Cp2(CO)3 scaffold (M = Fe, Ru; Cp = η5-C5H5), namely [M2Cp2(CO)2(µ-CO){µ,η1:η2-CH=C=CMe2}]BF4 (1Fe-Ru), [Ru2Cp2(CO)2(µ-CO){µ,η1:η2-C(Ph)=CHPh}]BF4 (2Ru) and [M2Cp2(CO)2(µ-CO){µ-CN(Me)(R)}]CF3SO3 (3Fe-Ru). While the reaction of 1Fe with Bu4NCN resulted in prevalent allenyl deprotonation, preliminary CO-NCMe substitution in 1Ru enabled cyanide addition to both the allenyl ligand (resulting in the formation of a h1:h2-allene derivative, 5A) and the two metal centers (affording 5B1 and 5B2). The mixture of 5B1-2 was rapidly converted into 5A in heptane solution at 100 °C, with 5A being isolated with a total yield of 60%. Following carbonyl-chloride substitution in 2Ru, CN− was incorporated as a terminal ligand upon Cl− displacement, to give the alkenyl complex 6 (84%). The reactivity of 3Fe and 3Ru is strongly influenced by both the metal element, M, and the aminocarbyne substituent, R. Thus, 7aRu was obtained with a 74% yield from cyanide attack on the carbyne in 3aRu (R = Cy, cyclohexyl), whereas the reaction involving the diiron counterpart 3aFe yielded an unclean mixture of the metastable 7aFe and the CO/CN− substitution product 8aFe. The cyano-alkylidene complexes 7aRu (R = Cy) and 7bFe (R = Me) underwent CO loss and carbene to carbyne conversion in isopropanol at 60–80 °C, giving 8aRu (48%) and 8bFe (71%), respectively. The novel compounds 5A, 5B1-2, 6 and 7aRu were characterized by IR and NMR spectroscopy, with the structure of 7aRu further elucidated by single crystal X-ray diffraction analysis. Additionally, the DFT-optimized structures of potential isomers of 5A, 5B1-2 and 6 were calculated. [ABSTRACT FROM AUTHOR]

We present a new synthetic strategy for obtaining mixed-valence triiron complexes where the metal centers are bridged by a novel, highly functionalized hydrocarbyl ligand. The alkynyl–vinyliminium complexes [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(X–C≡CH)CHCNMe2}]CF3SO3 (X = 4-C6H4, [2a1]CF3SO3; X = (CH2)3, [2a2]CF3SO3) were synthesized in almost quantitative yields from the aminocarbyne precursor [Fe2Cp2(CO)2(μ-CO){μ-CNMe2}]CF3SO3, [1a]CF3SO3, and the di-alkynes HC≡C–X–C≡CH. Then, the ferracycle [Fe(Cp)(CO){C(NMe2)CH＝C(4-C6H4C≡CH)C(O)}], 4a1, was produced in 47% yield from the cleavage of [2a1]CF3SO3 promoted by pyrrolidine. Subsequent reactions of the acetonitrile adducts [Fe2Cp2(CO)(μ-CO)(NCMe){μ-CNMe(R)}]CF3SO3 (R = Me, [1aACN]CF3SO3; R = Xyl, [1bACN]CF3SO3) ([FeIFeI]) with 4a1 ([FeII]) at room temperature resulted in the formation of [FeIFeIFeII] complexes [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(X–C＝CHC(NMe2)＝FeCp(CO)C＝O)CHCNMe(R)}]CF3SO3 (R = Me, [5a1]CF3SO3; R = Xyl, [5b1]CF3SO3) in yields ranging from 56% to 64%. The new products were characterized by IR and multinuclear NMR spectroscopy, and the structures of [2a2]CF3SO3 and 4a1 were confirmed by single crystal X-ray diffraction. Cyclic voltammetry and spectroelectrochemical studies on [5a1]+ have revealed that reduction and oxidation events occur almost independently at the [FeIFeI] and [FeII] units, respectively. This observation underscores a minimal electronic interaction between the two fragments within the triiron complex. Accordingly, DFT studies pointed out that the HOMO and LUMO orbitals are predominantly localized in the two distinct compartments of [5a1]+. [ABSTRACT FROM AUTHOR]

A reaction in anhydrous toluene between the formally unsaturated fragment [Ln(hfac)3] (Ln3+ = Eu3+, Gd3+ and Er3+; Hhfac = hexafluoroacetylacetone) and [Al(qNO)3] (HqNO = 8-hydroxyquinoline N-oxide), here prepared for the first time from [Al(OtBu)3] and HqNO, affords the dinuclear heterometallic compounds [Ln(hfac)3Al(qNO)3] (Ln3+ = Eu3+, Gd3+ and Er3+) in high yields. The molecular structures of these new compounds revealed a dinuclear species with three phenolic oxygen atoms bridging the two metal atoms. While the europium and gadolinium complexes show the coordination number (CN) 9 for the lanthanide centre, in the complex featuring the smaller erbium ion, only two oxygens bridge the two metal atoms for a resulting CN of 8. The reaction of [Eu(hfac)3] with [Alq3] (Hq = 8-hydroxyquinoline) in the same conditions yields a heterometallic product of composition [Eu(hfac)3Alq3]. A recrystallization attempt from hot heptane in air produced single crystals of two different morphologies and compositions: [Eu2(hfac)6Al2q4(OH)2] and [Eu2(hfac)6(µ-Hq)2]. The latter compound can be directly prepared from [Eu(hfac)3] and Hq at room temperature. Quantum mechanical calculations confirm (i) the higher stability of [Eu(hfac)3Al(qNO)3] vs. the corresponding [Eu(hfac)3Alq3] and (ii) the preference of the Er complexes for the CN 8, justifying the different behaviour in terms of the Lewis acidity of the metal centre. [ABSTRACT FROM AUTHOR]

While ruthenium(II) arene complexes have been widely investigated for their potential in catalytic transfer hydrogenation, studies on homologous compounds replacing the arene ligand with the six‐electron donor tris(1‐pyrazolyl)methane (tpm) are almost absent in the literature. The reactions of [RuCl(κ3‐tpm)(PPh3)2]Cl, 1, with a series of nitrogen ligands (L) proceeded with selective PPh3 mono‐substitution, affording the novel complexes [RuCl(κ3‐tpm)(PPh3)(L)]Cl (L=NCMe, 2; NCPh, 3; imidazole, 4) in almost quantitative yields. Products 2–4 were fully characterized by IR and multinuclear NMR spectroscopy, moreover the molecular structure of 4 was ascertained by single crystal X‐ray diffraction. Compounds 2–4 were evaluated as catalytic precursors in the transfer hydrogenation of a series of ketones with isopropanol as the hydrogen source, and 2 exhibited the highest activity. Extensive NMR experiments and DFT calculations allowed to elucidate the mechanism of the transfer hydrogenation process, suggesting the crucial role played by the tpm ligand, reversibly switching from tri‐ to bidentate coordination during the catalytic cycle. [ABSTRACT FROM AUTHOR]

Novel diiron vinyliminium complexes, [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(R3)＝CHC＝NMe(R2)}]CF3SO3 (2a–f; R2 = 4-C6H4OMe, Cy or Me; R3 = Cy, CH2Cy or 4-C6H4OMe; Cy = cyclohexyl, Cp = η5-C5H5), were synthesized by alkyne insertion reaction from the corresponding diiron aminocarbyne precursors, and isolated in 53–98% yields. The reactions of selected vinyliminium complexes with N2CHCO2Et and MeONa, followed by N-methylation, afforded the new hydrazone-vinyliminium [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(R3)C(NMeN＝CHCO2Et)CN(R1)(R2)}]X (4a–c; R1 = Me or CH2Ph; R2 = Cy, CH2Ph or Me; R3 = 4-C6H4OMe or Ph; X = NO3 or CF3SO3), in 53–67% yields. Compounds 2a–f and 4a–c were fully characterized by IR and multinuclear NMR spectroscopy, and the structures of 2a–c were ascertained by single crystal X-ray diffraction. Moreover, D2O solubility, Log Pow coefficients and the fraction of each complex preserved in aqueous media after 72 hours at 37 °C were determined by 1H NMR and UV-Vis methods. The antiproliferative activity of 2a–f and 4a–c was measured on the mouse colon CT26 and human glioblastoma U87 cancer cell lines, and on the retinal pigment epithelial RPE-1 non-cancerous cell line. Complexes 2a,d,e, which all bear R3 = Cy, stand out for their performance and their selectivity towards cancer cells. To give insight into the mechanism of action, the effect of 2a, 2d, 2e, 2f, 4b and 4c on the mitochondrial respiration was evaluated in CT26 cells (Seahorse Mito stress test), revealing a correlation between the effectiveness of the complexes and their influence on the mitochondrial metabolism. [ABSTRACT FROM AUTHOR]

Diiron μ-aminocarbyne complexes [Fe2Cp2(NCMe)(CO)(μ-CO){μ-CN(Me)(R)}]CF3SO3 (R = Xyl, [1aNCMe]CF3SO3; R = Me, [1bNCMe]CF3SO3; R = Cy, [1cNCMe]CF3SO3; R = CH2Ph, [1dNCMe]CF3SO3), freshly prepared from tricarbonyl precursors [1a–d]CF3SO3, reacted with NaOCN (in acetone) and NBu4SCN (in dichloromethane) to give [Fe2Cp2(kN-NCO)(CO)(μ-CO){μ-CN(Me)(R)}] (R = Xyl, 2a; Me, 2b; Cy, 2c) and [Fe2Cp2(kN-NCS)(CO)(μ-CO){μ-CN(Me)(CH2Ph)}], 3 in 67–81% yields via substitution of the acetonitrile ligand. The reaction of [1aNCMe–1cNCMe]CF3SO3 with KSeCN in THF at reflux temperature led to the cyanide complexes [Fe2Cp2(CN)(CO)(μ-CO){μ-CNMe(R)}], 6a–c (45–67%). When the reaction of [1aNCMe]CF3SO3 with KSeCN was performed in acetone at room temperature, subsequent careful chromatography allowed the separation of moderate amounts of [Fe2Cp2(kSe-SeCN)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 4a, and [Fe2Cp2(kN-NCSe)(CO)(μ-CO){μ-CN(Me)(Xyl)}], 5a. All products were fully characterized by elemental analysis, IR, and multinuclear NMR spectroscopy; moreover, the molecular structure of trans-6b was ascertained by single crystal X-ray diffraction. DFT calculations were carried out to shed light on the coordination mode and stability of the {NCSe-} fragment. [ABSTRACT FROM AUTHOR]

The catalytic activity of a series of diiron complexes based on the {Fe2Cp2(CO)x} core (x = 2–3) and containing a bridging aminocarbyne ligand was screened in transfer hydrogenation reaction of cyclohexanone from isopropanol. The series includes cationic tricarbonyl complexes, [1a–d]CF3SO3, and neutral derivatives obtained by substitution of one carbonyl with hydride (2a–c), cyanide (3a–d) or chloride (4a) ligands. The novel compounds 2a–b, 3a–b and 4a were characterized by analytical and spectroscopic techniques, and the single crystal X‐ray structure of one isomer of 4a was determined. In general, diiron complexes exhibited a moderate activity in combination with potassium hydroxide; [Fe2Cp2(CN)(CO)(μ‐CO){μ‐CN (Me)(4‐C6H4OMe)}], 3a, emerged as the best catalyst, and the study of its activity was extended to a range of other ketones. DFT calculations suggest an unusual carbyne‐centred mechanism, and the better performance displayed by 3a is ascribable to the stabilizing effect provided by the cyanide co‐ligand, which is experimentally supported by IR analyses. [ABSTRACT FROM AUTHOR]

The similar reactivity of lanthanides generally leads to statistically populated polynuclear complexes, making the rational design of ordered hetero‐lanthanide compounds extremely challenging. Here we report on the site selectivity in hetero‐lanthanide tetranuclear complexes afforded by the relatively simple ditopic pyterpyNO ligand (4'‐(4‐pyridil)‐2,2':6',2"‐terpyridine N‐oxide). The sequential room temperature reaction of RE2(tta)6(pyterpyNO)2 (where RE=Y, (1); Eu, (2), Dy, (3) Htta=2‐thenoyltrifluoroacetone) with La(tta)3dme (dme=dimethoxyethane) yielded Y2La2(tta)12(pyterpyNO)2 (4), Dy2La2(tta)12(pyterpyNO)2 (5) and Eu2La2(tta)12(pyterpyNO)2 (6). Single crystals X‐ray diffraction studies showed that 4, 5 and 6 are isostructural, featuring a tetranuclear structure with two different metal coordination sites with coordination numbers 8 (CN8) and 9 (CN9). The two smaller cations are mainly bridged by the O‐donor atoms of the NO groups of two pyterpyNO ligands (CN8), while the larger lanthanum centres are bound by a terpyridine unit (CN9). Size selectivity has been studied with structural and magnetic studies in the solid state and through 19F NMR and photoluminescence studies in solution, showing a direct dependence on the difference of ionic radii of the ions and yielding a 91 % selectivity for 4. Furthermore, 19F NMR, X‐ray and PL studies pointed out that the nature of the product is independent from the synthetic route for compound Eu2Y2(tta)12(pyterpyNO)2 (7), keeping the ion selectivity also for a self‐assembly reaction. Unexpectedly, these studies have evidenced that selectivity is not exclusively governed by electrostatic interactions related to size dimensions. [ABSTRACT FROM AUTHOR]

In comparison with RuII-arene compounds, the medicinal potential of homologous RuII-tpm compounds [tpm = tris(pyrazolyl)methane] is underexplored. Pyridine, 4-pyridinemethanol and four functionalized pyridines, synthesized from the esterification of 4-pyridinemethanol with bioactive carboxylic acids (i.e., ethacrynic acid, ibuprofen, flurbiprofen and naproxen), react with the precursor [RuCl(κ3-tpm)(PPh3)2]Cl (1) to afford [RuCl(κ3-tpm)(PPh3)(L)]Cl (2–7, L = pyridine ligand), in 78–91% yields. All products were fully characterized by HR-ESI mass spectrometry, IR and multinuclear NMR spectroscopy and the solid-state structures of two of the complexes, i.e. where L = pyridine and 4-pyridinemethanol, were ascertained by single crystal X-ray diffraction. The {Ru-tpm-PPh3} assembly is stable in D2O and in biological medium (DMEM) at 37 °C, with a tendency to slowly dissociate the pyridine ligand. The antiproliferative activity of the complexes was assessed on the cancerous A2780 and A2780cisR cell lines, and the nontumoral HEK 293T cell line; moreover inhibition assays were carried out on the complexes towards COX-2 and GSTP1 enzymes. [ABSTRACT FROM AUTHOR]

Dimetallic complexes are suitable platforms for the assembly of small molecular units, and the reactivity of bridging alkenyl ligands has been widely investigated to model C–C bond forming processes. Here, we report the unusual coupling of an alkenyl ligand, bridging coordinated on a diruthenium scaffold, with a series of alkynes, revealing two possible outcomes. The diruthenium complex [Ru2Cp2(Cl)(CO)(μ-CO){μ–η1:η2-C(Ph)＝CH(Ph)}], 2, was prepared in two steps from [Ru2Cp2(CO)2(μ-CO){μ–η1:η2-C(Ph)＝CH(Ph)}]BF4, [1]BF4, in 69% yield. Then, the reaction of 2 with C2(CO2Me)2, promoted by AgCF3SO3 in dichloromethane, afforded in 51% yield the complex [Ru2Cp2(CO)2{μ–η3:η2-C(Ph)CH(Ph)C(CO2Me)C(CO2Me)}]CF3SO3, [3]CF3SO3, containing a ruthenacyclopentene-based hydrocarbyl ligand. On the other hand, 2 reacted with other alkynes and AgX salts to give the butadienyl complexes [Ru2Cp2(CO)2{μ–η3:η2-C(R)CH(R′)C(Ph)C(Ph)}]X (R = R′ = H, [4]BF4; R = R′ = Me, [5]CF3SO3; R = R′ = Ph, [6]CF3SO3; R = Ph, R′ = H, [7]CF3SO3), in 42–56% yields. All products were characterized by IR and NMR spectroscopy, and by single crystal X-ray diffraction in the cases of 2, [3]CF3SO3 and [6]BF4. DFT calculations highlighted the higher stability of [4–7]+-like structures with respect to the corresponding [3]+-like isomers. It is presumable that [3]+-like isomers initially form as kinetic intermediates, then undergo H-migration which is disfavoured in the presence of carboxylato substituents on the alkyne. Such hypothesis was supported by the computational optimization of the transition states for H-migration in the cases of R = R′ = H and R = R′ = CO2Me. [ABSTRACT FROM AUTHOR]

The room temperature reactions with internal alkynes, RC≡CR, of the μ-allenyl acetonitrile complex [Ru2Cp2(CO)2(NCMe){μ–η1:η2-C1H＝C2＝C3Me2}]BF4 (1-NCMe), freshly prepared from the tricarbonyl precursor [Ru2Cp2(CO)3{μ–η1:η2-C1H＝C2＝C3Me2}]BF4, 1, proceeded with alkyne insertion into ruthenium-allenyl bond and allenyl-CO coupling, affording compounds [Ru2Cp2(CO)2{μ–η2:η5-C(R)C(R)C1HC2(C3Me＝CH2)C(OH)}]BF4 (R = Ph, 2; R = CO2Me, 3; R = CO2Et, 4) in 83–94% yields. Deprotonation of 2–4 by triethylamine gave [Ru2Cp2(CO)2{μ–η2:η5-C(R)C(R)CHC(CMe＝CH2)C(O)}] (R = Ph, 5; R = CO2Me, 6; R = CO2Et, 7) in 75–88% yields, and 2–4 could be recovered upon HBF4·Et2O addition to 5–7. All the products, 2–7, were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. The structure of 2 was ascertained by single crystal X-ray diffraction and investigated by DFT calculations, revealing a six-membered ruthenacycle with Shannon aromaticity index in line with related compounds. The formation of ruthenium-coordinated ruthenabenzenes from a preexistent diruthenium scaffold is a versatile but underdeveloped approach exploiting cooperative effects typical of a dimetallic core. [ABSTRACT FROM AUTHOR]

A series of diiron complexes with two cyclopentadienyls, two carbonyls, and one bridging vinyl‐aminoalkylidene as ligands, [3a–h]CF3SO3 and [4a–d]CF3SO3, was synthesized in 66–94% yields from diiron μ‐aminocarbyne precursors. The subsequent reactions with pyrrolidine led to selective fragmentation to aminoalkylidene‐ferracyclopentenone derivatives (5a–h and 6a–c) in 30–84% yields. The compounds were characterized by elemental analysis, Fourier transform infrared and NMR spectroscopy, and by single crystal X‐ray diffraction in three cases. The stability in aqueous media relevant to biological trials, the carbon monoxide release, and the catalytic activity in NADH oxidation were evaluated for selected compounds by NMR spectroscopy and gas chromatography. The in vitro antiproliferative activity of the compounds was determined towards cancer (A2780, A2780cisR) and noncancer (HEK‐293) cell lines. Moreover, the antibacterial activity was tested on Gram‐positive (vancomycin‐resistant E. faecium and methicillin‐resistant S. aureus) and Gram‐negative strains (A. baumannii and P. aeruginosa). [ABSTRACT FROM AUTHOR]

Single-crystal-to-single-crystal post-synthetic modifications (PSMs) of Lanthanide Organic Frameworks (LOFs) {[Ln2(H2L)3(DMF)4]·2DMF}n (Ln = Gd, 1 and Eu, 2; H4L = 2,5-dihydroxyterephthalic acid; DMF = dimethylformamide), carried out by treatment with (a) chloroform or (b) an imidazole solution in chloroform, yielded respectively isostructural {[Ln2(H2L)3(DMF)4]·CHCl3}n (Ln = Gd, 3; Eu, 4) or {[Ln2(H2L)3(Im)4][Ln2(H2L)3(Im)2(H2O)2]·6Im·2CHCl3}n (Ln = Gd, 5; Eu, 6). Single crystal X-ray diffraction studies of 5 showed two different regularly alternating dimeric units in the LOF and two regularly alternating cavities with different guest molecules. All compounds revert to the parent LOF, 1 or 2, when treated with DMF at 90 °C for 8 h. Europium-LOFs (2, 4 and 6) showed a faint red emission that progressively gained intensity upon cooling from RT to liquid nitrogen temperature. This behaviour was exploited to develop a family of luminescent thermometers whose characteristics were affected by the structural and coordinative modifications induced by PSMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of coinage metal complexes in 1,2-diamines as solvent. • 1:1:2 ionic/mononuclear complexes of silver and copper with triphenylphosphine and 1,2 diamine ligands. • Structure determination of mixed-ligands Cu(I) and Ag(I) complexes shows two crystallographically independent cations which are conformationally different. Crystallization of copper(I) halide : triphenylphosphine mixtures from 1,2-diaminoethane (en = ethylenediamine) has yielded adducts 1:1:2 CuX:PPh 3 :en stoichiometry (X = Cl or I); the chloride and iodide have been characterized by room temperature single crystal X-ray structure determinations; the iodide is a hemisolvate. In both cases, the complex is ionic, the four coordinate CuPN 3 environment comprising both bidentate and unidentate en, i.e [(κ2- N,N' -en)(κ1- N -en)(PPh 3)Cu]+X−. In each case, there are two crystallographically independent cations which are conformationally different. Adduct [(PPh 3)(κ 2- N,N' -en)(κ 1- N -en)Cu]Cl is very unstable and decomposes on air, whereas [(κ 2- N,N' -en)(κ 1- N -en)(PPh 3)Cu]I is sufficiently stable both in the solid state and in solution to be characterized. Adducts of similar stoichiometry are obtained with silver(I) nitrate, and with silver(I) perchlorate with PCy 3 , and 1,2-diaminopropane (pn): the single crystal X-ray structure determinations confirm the ionic/mononuclear formulations [(κ2- N,N' -en)(κ1- N -en)(PPh 3)Ag]NO 3 and [(κ2- N,N' -en)(κ1- N -en)(PCy 3)Ag]ClO 4 that persist also in acetonitrile, as confirmed by conductance values typical of 1:1 electrolytes in this solvent. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dinuclear ionic derivatives of formula [Ag(EPh 3)(en) 2 ] 2 X 2 have been synthesized. • First dinuclear silver derivatives containing both EPh 3 and en ligands. • X-ray studies show en acting both as bridging linker between two Ag centres and as monodentate ligand. • Ancillary ligands EPh 3 strongly influence the Ag-N bond distances and N -Ag-N bond angles. Colourless crystalline adducts obtained by the crystallization of various silver(I) compounds in 1:1 M proportions with EPh 3 (E = P, As, Sb) from 1,2-diaminoethane (ethylenediamine) (en ≡ H 2 N(CH 2) 2 NH 2) have been structurally characterized by room temperature single crystal X-ray studies as 1:1:2 AgX: EPh 3 : en adducts. The array of compounds is isomorphous, triclinic, P 1 ¯ , a ~ 8.5, b ~ 9.2, c ~ 16.9 Å, α ~ 86.6, β ~ 80, γ ~ 65.5°, Z = 1 dimer, being ionic [(Ph 2 E)(N -en)Ag(N -en- N') 2 Ag(N -en)(EPh 3)]2+(X−) 2 , with binuclear centrosymmetric cations containing four-coordinate silver; the nitrogen component of the latter N 3 AgE array is made up of a pair of N from two bridging en groups and, remarkably, one N from unidentate N -en. Compounds have been spectroscopically and structurally characterized for E = P, X = Cl, Br; E = As, X = Cl, Br; E = Sb, X = Cl, Br, NO 3. Bond distances and angles are compared with previous report on literature for AgX: en adducts. [ABSTRACT FROM AUTHOR]

Nitriles (N≡CR) are ubiquitous in coordination chemistry, yet literature studies on metal–nitrile bonding based on a multi-technique approach are rare. We selected an easily-available di-organoiron framework, containing both π-acceptor (CO, aminocarbyne) and donor (Cp = η5−C5H5) ligands, as a suitable system to provide a comprehensive description of the iron–nitrile bond. Thus, the new nitrile (2–12)CF3SO3 and the related imine/amine complexes (8–9)CF3SO3 were synthesized in 58–83% yields from the respective tris-carbonyl precursors (1a–d)CF3SO3, using the TMNO strategy (TMNO = trimethylamine-N-oxide). The products were fully characterized by elemental analysis, IR (solution and solid state) and multinuclear NMR spectroscopy. In addition, the structures of (2)CF3SO3, (3)CF3SO3, (5)CF3SO3 and (11)CF3SO3 were ascertained by single crystal X-ray diffraction. Salient spectroscopic data of the nitrile complexes are coherent with the scale of electron-donor power of the R substituents; otherwise, this scale does not match the degree of Fe → N π-back-donation and the Fe–N bond energies, which were elucidated in (2–7)CF3SO3 by DFT calculations. [ABSTRACT FROM AUTHOR]

Single crystal X-ray diffraction analysis revealed the uncommon coordination of butadiene to two identical iron(II) cyclopentadienyl moieties, and DFT calculations highlighted the stabilizing contribution of an intramolecular bonding network involving isocyanide ligands. [Display omitted] • Iron(II) complex with trans-1,3-butadiene ligand was serendipitously obtained. • Electron-donor substituents are crucial in stabilizing alkene coordination to iron(II) Cp. • Ancillary benzylisocyanide ligands are decisive to allow solid-state isolation here. The unexpected isolation and crystallographic characterization of the 1,3-butadiene complex [{FeCp(CNBn) 2 } 2 (μ-η2:η2- trans -C 4 H 6)][CF 3 SO 3 ] 2 , 3 (Cp = η5-C 5 H 5 , Bn = CH 2 Ph), represents a rare example of bridging- trans coordination of the butadiene ligand between two iron(II) fragments. An extensive comparative DFT study was conducted to elucidate the bonding of butadiene in 3 and related complexes. This study unveiled the stabilizing contribution provided by intramolecular interactions involving the diene moiety and the ring electrons of the phenyl groups belonging to CNBn. [ABSTRACT FROM AUTHOR]

Neutral complexes with generic formula [PtCl 2 (PPh 3 )(L)] were efficiently oxidized to [PtCl 4 (PPh 3 )(L)] (L = dibenzylamine, p -toluidine, diethanolamine, pyridine and acetonitrile) using PhICl 2 The anionic complex [TBA][PtCl 3 (PPh 3 )] (TBA = Tetrabutylammonium) was also oxidized to [TBA][PtCl 5 (PPh 3 )] with this method. The obtained products were fully characterized by 1 H, 13 C, 31 P and 195 Pt NMR, IR-ATR spectroscopy, elemental analysis and, for complexes cis -([PtCl 4 (PPh 3 )( p -toluidine)]·CHCl 3 and trans -[PtCl 4 (PPh 3 )(NCCH 3 )]·CH 3 CN, also by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

[Display omitted] The unprecedented cyanylation of an isocyanide ligand was achieved on a diiron scaffold using cyanogen bromide, and led to the first structural characterization of a N -cyano substituted aminoalkylidene ligand. • Aminoalkylidyne ligands are ubiquitous in organometallic chemistry. • N -cyano-aminoalkylidene ligands were unknown up to now. • Cyanylation reactions on metal complexes are usually hampered by competitive oxidation/bromination pathways. • Cyanogen bromide reacted as both CN+ and CN– transferor towards an isocyanide ligand in diiron complex. • The first structural characterization of a N -cyano-aminoalkylidene complex is reported. The reaction of the isocyanide complex [Fe 2 Cp 2 (CO) 3 (CNMe)], 1Me , with BrCN (1.2 eq.), in acetonitrile at 60 °C, led to the low-yield isolation, after work-up, of the unprecedented N -methylcyanamido-(cyano)alkylidene complex [Fe 2 Cp 2 (CO) 3 {μ-C(CN)N(CN)Me}], 3. The synthesis of 3 represents an uncommon example of C C bond forming cyanylation reaction taking place at a metal complex despite competitive oxidative addition pathways; it proceeded with the presumable, intermediate formation of a N -methylcyanamido-alkylidyne precursor readily undergoing CN– addition, and was accompanied by the production of minor amounts of [Fe 2 Cp 2 (CO) 4 ] and monoiron(II) piano-stool compounds. Compound 3 was fully characterized by single crystal X-ray diffraction, elemental analysis, IR and NMR spectroscopy. The reaction of [Fe 2 Cp 2 (CO) 4 ] with cyanogen bromide, under conditions resembling those employed for 1Me /BrCN, afforded a mixture of [FeCpBr(CO) 2 ] and [FeCp(CN)(CO) 2 ]. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dinuclear 1:1 adducts [{(o-tol) 3 P}Ag(X) 2 Ag{P(o-tol) 3 }] 2 are obtained with bridging counter-ion X = tfa, Cl, NCO, ac, ClO 4. • Mononuclear 1:1 adduct [{(o-tol) 3 P}Ag(NO 3)] contains a chelating nitrate. • Tetranuclear 1:1 adducts [{R 3 P}AgX] 4 are obtained with X = NCO and Br when R = Ph, and X = I when R = cy. • The polynuclear 1:2 adduct [{(o-tolyl) 3 P}(AgCN) 2 } ∞ displays a complex two-dimensional array. Syntheses, spectroscopy and single crystal X-ray structural characterizations are recorded for a number of adducts AgX: PR 3 (1:1) n obtained from the reaction of silver(I) salts with sterically hindered tertiary phosphine bases, extending previous studies. With tris(o -tolyl)phosphine, P(o -tolyl) 3 , binuclear adducts AgX: P(o -tolyl) 3 (1:1) 2 are defined, in arrays with eight-membered central rings [(o -to1yl) 3 PAg(μ-tfa) 2 AgP(o -tolyl) 3 ] (1) (tfa = trifluoroacetate, O.CO.CF 3) where two independent atoms of the anion bridge to the two silver atoms, and four-membered central rings where one atom bridges (Cl, N CO, acetate (= 'ac', O.CO.CH 3)) (complexes 2 – 4); the perchlorate (5) is intermediate, one perchlorate bridging via one oxygen and the other by two. The nitrate is mononuclear, [(o -tolyl) 3 PAg O 2 NO], (6) with chelating nitrate. The bromide takes a tetranuclear 'cubane' form (7). With the cyanide, an interesting 2:1 AgCN: (o -tolyl) 3 P adduct (8) is defined as a two-dimensional polymer. The archetypical cubane series with triphenylphosphine is extended with a new bromide structure, MeCN solvated [(Ph 3 P)AgBr] 4.0.22MeCN (9), to encompass also the cyanate [(Ph 3 P)Ag(N CO)] 4 (10), isomorphous with the previously defined Cu/As/I chloroform solvate. The 'cubane' form is defined also for a further iodide polymorph AgI: Pcy 3 (1:1) 4 (11). [ABSTRACT FROM AUTHOR]

Derivatives of [M 2 Cp 2 (CO) 4 ] (M = Fe or Ru) containing, respectively, an isocyanide or a bridging aminocarbyne ligand display little structural and spectroscopic differences. Higher back-bonding to π-acceptor ligands is clearly appreciated by IR spectroscopy in cationic diiron species with respect to the diruthenium homologues. [Display omitted] • [M 2 Cp 2 (CO) 4 ] (M = Fe, Ru) as useful platform to install bridging hydrocarbyl ligands. • Carbonyl/isocyanide substitution has been explored on the diruthenium system. • Isocyanide ligand alkylation provides access to cationic aminocarbyne complexes. • Enhanced π-back donation is appreciated in the cationic diiron vs. diruthenium complexes. The chemistry of [Fe 2 Cp 2 (CO) 4 ] (1-Fe ; Cp = η5-C 5 H 5) has been widely investigated, and straightforward carbonyl/isocyanide substitution, followed by isocyanide alkylation, provides access to a variety of aminocarbyne complexes, displaying a rich and versatile reactivity. On the other hand, the parallel chemistry of [Ru 2 Cp 2 (CO) 4 ] (1-Ru) has been much less developed, and relevant structural/bonding aspects scarcely elucidated. We report an IR study on 1-Ru in different solvents and in the solid state. The IR data of [M 2 Cp 2 (CO) 3 (CNR)] (M = Ru, R = 2,6-C 6 H 3 Me 2 = Xyl, 2a-Ru ; M = Ru, R = CH 2 Ph = Bn, 2b-Ru ; M = Ru, R = Me, 2c-Ru ; M = Fe, R = Xyl, 2a-Fe ; M = Fe, R = Bn, 2b-Fe ; M = Fe, R = Me, 2c-Fe) and [M 2 Cp 2 (CO) 3 {μ-CNR(Me)}]CF 3 SO 3 (M = Ru, R = Xyl, 4a-Ru ; M = Ru, R = Bn, 4b-Ru ; M = Ru, R = Me, 4c-Ru ; M = Fe, R = Xyl, 4a-Fe ; M = Fe, R = Bn, 4b-Fe ; M = Fe, R = Me, 4c-Fe) are comparatively presented, and the back-donation from the dimetallic core to π-acceptor ligands in complexes 4 is discussed. A new synthetic procedure to access 2a-Ru is reported, affording [Ru 2 Cp 2 (CO) 2 (CNXyl) 2 ] (3) as by-product, as well as the single crystal X-ray structures of 2b-Ru and 4b-Ru. DFT calculations were carried out to elucidate the relative stability of isomeric forms within the series of isocyanide adducts 2-Ru and 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of coinage metal complexes in 1,2-diamines as solvent. • 1:1:1 complexes of silver and copper with phosphine and 1,2 diamine ligands. • Structure determination of mixed-ligands Cu and Ag complexes. • Comparison of structural parameters in [M(N 2 -donor)(P-donor)X] complexes (M = Ag, Cu). Crystallization of adducts of simple copper(I) and silver(I) salts (MX) with triphenylphosphine from ' N,N,N′,N '-tetramethylethylenediamine', 'tmeda', has yielded adducts of 1:1:1 MX:PPh 3 :tmeda stoichiometry, all of which have been characterized by room temperature single crystal X-ray structure determinations. In all adducts, the complex is mononuclear [M(PPh 3)(N,N ′-tmeda)X] with four-coordinate N 2 PMX metal atom environments (M = Cu, X = Cl, Br, I; M = Ag, X = Cl or NO 3). The tricyclohexylphosphine species [Ag(Pcy 3)(N,N ′-tmeda)(ONO 2)], also in a N 2 PAgX metal environment, has been defined. A number of similar silver(I) adducts are obtained by using 1,2-diaminopropane, 'pn' as solvent. The chloride, bromide and iodide complexes are isomorphous, the complexes being mononuclear, [Ag(PPh 3)(pn)X], with four-coordinate N 2 PAgX environments, the pn ligand chelating. An isomorphous arsenic analogue of the bromide has also been isolated. All complexes have been characterized by IR and NMR (1H and 31P) spectroscopy. [ABSTRACT FROM AUTHOR]

Trans -[PtCl 4 (NCMe)(PPh 3)] promptly reacts with nucleophiles L (L = pyridine, quinoline, isoquinoline, benzothiazole, o-, m-, p-toluidine) affording the corresponding acetonitrile substitution products. Even when protic o-, m- and p-toluidines were used, chemoselectivity towards substitution was observed, with addition products formed in less than 10% extent. • MeCN in the title Pt(IV) compound is promptly substituted by N -nucleophiles. • N -heteroaromatic nucleophiles were successfully used in the substitution reaction. • The reaction with toluidines was chemoselective towards substitution products. Despite the generally accepted inertness of platinum(IV) complexes towards nucleophilic substitution, the title compound promptly reacts with nucleophiles L (L = pyridine, quinoline, isoquinoline, benzothiazole, o-, m-, p-toluidine) affording the corresponding acetonitrile substitution products. To follow the reaction spectroscopically, a series of platinum(IV) standards were prepared by bridge splitting of trans- [Pt(μ-Cl)Cl(PPh 3)] 2 , followed by oxidation by PhICl 2. All the new platinum(II) and platinum(IV) complexes were fully characterized, and, in some cases, the structure was studied by single crystal X-ray diffraction. Even when protic o-, m- and p-toluidines were used, chemoselectivity towards substitution was observed, with addition products formed in less than 10% extent. [ABSTRACT FROM AUTHOR]

Gd(III), Yb(III) and Lu(III) complexes containing 1,10-phenantroline and 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dionate can act as an efficient antenna for the sensitization of Yb3+ NIR luminescence at 980 nm • Ln(III) complexes of a new 1,3-pyrazolyl-diketone and 1,10-phenantroline. • Comparison of bond distances and angles in [Ln(diketonate) 3 (N 2 -donor)] species. • Luminescent [Yb(L) 3 (phen)] species. • Synthetic methods for preparation of crystalline [Yb(L) 3 (phen)] species. Three novel lanthanide complexes based on 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dionate (L), namely [Ln(L) 3 (phen)] (Ln = Gd, Yb, Lu; phen = 1,10-phenanthroline) were synthesized and characterized by spectroscopy and single crystal X-ray study that revealed a monomeric nature for the three compounds. Comparison of the molecular parameters has been made with analogous [Ln(diketonate) 3 (N 2 -donor)] species. The peculiarities of the coordination polyhedron and the photophysical properties for the three complexes were discussed. It has been found that, despite relatively high energy of triplet state of the ligand L (T 1 = 22,000 cm−1) unfavorable for sensibilization of Yb3+ ion, the ytterbium complex is noticeable luminescent. The emission Stark-splitted maximum in photoluminescence spectrum of [Yb(L) 3 (phen)] is peaked at 980 nm (NIR-region) and photoluminescence quantum yield (PLQY) is about 0.3%. [ABSTRACT FROM AUTHOR]

• The interaction between 1-phenyl-3-methyl-4-cyclohexylcarbonyl-pyrazol-5-one (HQCY) and europium and gadolinium nitrates in presence of various alkilis (MOH = LiOH-CsOH) in various ratios was studied. • Unexpectedly, it turned out, that in any ratio only tris-complexes could be obtained. • The structure of [Eu(QCY) 3 (H 2 O)] was investigated, and luminescence of europium and gadolinium complexes was studied. • The uniquely high energy of triplet level of ligand was verified both with spectroscopy and TD-DFT. Two new lanthanide (III) complexes, namely [Ln(QCy) 3 (H 2 O)] (Ln = Eu (1), Gd (2); HQCy = 1-phenyl-3-methyl-4-cyclohexylcarbonyl-pyrazol-5-one), have been obtained by reaction of corresponding Ln(NO 3) 3 ·xH 2 O with excess of HQCy and MOH, M = Li, Na, K or Cs. Unexpectedly, formation of the [Ln(QCy) 4 ]− species was not observed, also when the reaction was carried out in ligand excess and by varying reaction conditions and molar ratios. [Eu(QCy) 3 (H 2 O)] (1) has been structurally characterized by single crystal X-ray study. The crystal structure of 1 is based on molecular [Eu(QCy) 3 (H 2 O)] moieties connected by O H...N hydrogen bonds into 1D-chain. Phosphorescence spectra of 2 allowed to determine the very high energy of the triplet level of the ligand (QCy) 23,640 cm−1, which correlates well with the calculated value of 24,040 cm−1. Weak luminescence of the europium species 1 is observed even at room temperature. [ABSTRACT FROM AUTHOR]

The MOF {[Gd 2 (H 2 L) 3 (DMF) 4 ]·2DMF} n (H 4 L = 2,5-dihydroxyterephthalic acid) has been cleanly converted into two different MOFs: {[Gd 2 (H 2 L) 3 (H 2 O) 6 ]·2H 2 O} n and {[Gd 2 (H 2 L)(L)(H 2 O) 5 ]·2H 2 O} n with modifications in the MOF architecture that can be reverted. • Gadolinium-based metal organic frameworks were interconverted. • Structural conversion from dinuclear units to rows of metals. • MOF room temperature synthesis. The reaction of a lanthanide precursor with 2,5-dihydroxyterephthalic acid (H 4 L) yields different MOFs, having [H 2 L]2− and [L]4− as anionic spacers, in different synthetic conditions. The interconversion conditions have been established for some of them. The known gadolinium coordination polymer (CP) {[Gd 2 (H 2 L) 3 (DMF) 4 ]·2DMF} n (DMF = N,N -dimethylformamide), 1 , was prepared in DMF, either at 90 °C or also at room temperature, if assisted by a base diffusion. NMR monitoring for the synthesis of the analogous yttrium system (DMF, 90 °C) showed that the reaction progress relates with the formation of NHMe 2 by DMF decomposition. {[Y 2 (H 2 L) 3 (DMF) 4 ]·2DMF} n , 2 , isotypic with 1 , was obtained. The new structurally characterized CP {[Gd 2 (H 2 L) 3 (H 2 O) 6 ]·2H 2 O} n 3 , has been prepared by initial thermal (T = 170 °C) desolvation of 1 in vacuo (P = 1·10−3 Torr), followed by a hydrothermal treatment. Interestingly, 3 reverted back to 1 by treatment in DMF at 90 °C. Moreover 3 has been obtained starting from the metal nitrate and H 4 L in hydrothermal conditions (140 °C; 12 h) in the presence of the stoichiometric amount of NaOH. Long reaction times produced the intermediate formation of a mixture where it was possible to identify the new structurally characterized {[Gd 2 (H 2 L) 3 ]·2H 2 O} n , 4 , the known {[Gd 2 (H 2 L) 2 (L) 0.5 (H 2 O) 3 ]·4H 2 O} n , 5 and {[Gd 2 (H 2 L)(L)(H 2 O) 5 ]·2H 2 O} n , 6 , while at higher temperature (160 °C; 24 h) the pure 6 was obtained. The observed transformations of 1 into 6 in H 2 O involve H 4 L elimination. On the other hand, it was found that the treatment of 6 in DMF in the presence of H 4 L leads back to 1. Single Crystal X Ray Diffraction (SCXRD) studies were carried out on the new species 2 , 3 and 4. [ABSTRACT FROM AUTHOR]