Zwitterionic Rhodium and Iridium Complexes Based on a Carboxylate Bridge-Functionalized Bis-N-heterocyclic Carbene Ligand: Synthesis, Structure, Dynamic Behavior, and Reactivity

A series of water-soluble zwitterionic complexes featuring a carboxylate bridge-functionalized bis-N-heterocyclic carbene ligand of formula [Cp MIIICl{(MeIm)2CHCOO}] and [MI(diene){(MeIm)2CHCOO}] (Cp* = 1, 2, 3, 4, 5-pentamethylcyclopentadienyl; M = Rh, Ir; MeIm = 3-methylimidazol-2-yliden-1-yl; diene = 1, 5-cyclooctadiene (cod), norbornadiene (nbd)) were prepared from the salt [(MeImH)2CHCOO]Br and suitable metal precursor. The solid-state structure of both types of complexes shows a boat-shaped six-membered metallacycle derived of the ¿2C, C' coordination mode of the bis-NHC ligand. The uncoordinated carboxylate fragment is found at the bowsprit position in the Cp MIII complexes, whereas in the MI(diene) complexes it is at the flagpole position of the metallacycle. The complexes [RhI(diene){(MeIm)2CHCOO}] (diene = cod, nbd) exist as two conformational isomers in dichloromethane, bowsprit and flagpole, that interconvert through the boat-to-boat inversion of the metallacycle. An inversion barrier of ~17 kcal·mol-1 was determined by two-dimensional exchange spectroscopy NMR measurements for [RhI(cod){(MeIm)2CHCOO}]. Reaction of zwitterionic Cp MIII complexes with methyl triflate or tetrafluoroboric acid affords the cationic complexes [Cp MIIICl{(MeIm)2CHCOOMe}]+ or [Cp MIIICl{(MeIm)2CHCOOH}]+ (M = Rh, Ir) featuring carboxy and methoxycarbonyl functionalized methylene-bridged bis-NHC ligands, respectively. Similarly, complexes [MI(diene){(MeIm)2CHCOOMe}]+ (M = Rh, Ir) were prepared by alkylation of the corresponding zwitterionic MI(diene) complexes with methyl triflate. In contrast, reaction of [IrI(cod){(MeIm)2CHCOO}] with HBF4·Et2O (Et = ethyl), CH3OTf, CH3I, or I2 gives cationic iridium(III) octahedral complexes [IrIIIX(cod){(MeIm)2CHCOO}]+ (X = H, Me, or I) featuring a tripodal coordination mode of the carboxylate bridge-functionalized bis-NHC ligand. The switch from ¿2C, C' to ¿3C, C', O coordination of the bis-NHC ligand accompanying the oxidative addition prevents the coordination of the anions eventually formed in the process that remain as counterions

Synthesis of Titanium and Zirconium Complexes with 2-Pyridonate and 2, 6-Pyridinedithiolate Ligands

Treatment of complex Cp2TiCl2] with the lithium salt of 2-hydroxypyridine afforded complex Cp2Ti(Opy)2] (1), whereas the same synthetic strategy applied to the analogous zirconium compound Cp2ZrCl2] did not worked. However, the use of the metallocene Cptt 2ZrMe2] with protic ligands allowed directing the reactivity towards protonation of the methyl groups attached to zirconium. To check this approach we reacted Cptt 2ZrMe2] with methanol affording complex Cptt 2ZrMe(OMe)] (2), which was characterized in situ by NMR techniques. In the same line, the reaction of Cptt 2ZrMe2] with 2-hydroxypyridine gave complex Cptt 2Zr(Me)(Opy)] (3)//forcing the conditions of this reaction did not lead to the expected complex Cptt 2Zr(Opy)2], most probably due to the steric hindrance exerted by the bulky cyclopentadienyl ligands. Further reactions of complex 3 with ligands having acidic protons also led to the recovery of the starting complex. However, when shifting to the bifunctional ligand 2, 6-dimercaptopyridine py(SH)2] a double protonation of the methyl ligands in Cptt 2ZrMe2] occurred, allowing the isolation of mononuclear complex Cptt 2Zr(¿S, ¿S, ¿N-pyS2)] (4), upon evolution of methane. The molecular structure of complex 4 was determined by X-ray methods, showing the zirconium atom in a highly distorted trigonal bipyramidal arrangement//structural parameters indicate a conventional Zr-N bond, but rather weak Zr-S interactions

Brote familiar de brucelosis. La importancia de la sospecha epidemiológica

Objetivo: La brucelosis es la zoonosis más extendida en el mundo. En España su incidencia ha disminuido considerablemente en los últimos años gracias a las medidas sociosanitarias llevadas a cabo. Se han comunicado 40 casos de brucelosis en humanos en 2018, lo que representa una tasa de 0, 09 por cada 100.000 habitantes. El objetivo de este estudio fue destacar la importancia de la vigilancia activa y del cribado en familiares de pacientes diagnosticados de brucelosis. Metodos: Se realizó un estudio descriptivo de un brote familiar de brucelosis importada. Se evaluaron cinco miembros de una misma familia tras el diagnóstico de brucelosis de un paciente en el Área III de Salud de Zaragoza, en mayo de 2019. Se contactó telefónicamente con los familiares del paciente y el centro de salud para investigar la posibilidad de afectación de los familiares con quienes había viajado y convivido en Marruecos. Resultados: En un escenario de escasa frecuencia de enfermedad como es nuestro país en el momento actual, el cribado familiar, tras un diagnóstico inicial de brucelosis importada, permitió detectar y tratar a cuatro miembros de una misma familia de origen magrebí. Resultaron contagiados durante un viaje en abril de 2019 a su lugar de origen, un mes en el que convivieron en el ámbito rural en contacto con animales (ovejas, cabras, vacas) y consumieron productos lácteos y cárnicos. La aparición de síntomas presentados concordó temporalmente con el periodo de incubación de la enfermedad. Conclusiones: Destaca la importancia de la vigilancia activa y del cribado en familiares de pacientes diagnosticados de brucelosis, ya que comparten, por lo general, exposiciones a una fuente común. Background: Brucellosis is the most widespread zoonosis in the world. In Spain its incidence has decreased considerably in recent years thanks to the social and health measures carried out. 40 cases of brucellosis have been reported in humans in 2018, representing a rate of 0.09 per 100, 000 inhabitants. The objective of the study was to highlight the importance of epidemiological suspicion, as well as the screening of relatives for the diagnosis of the disease. Methods: A descriptive study of a family outbreak of imported brucellosis was carried out. Five members of the same family were evaluated after the diagnosis of brucellosis in a patient in the Health Area III of Zaragoza, in May 2019. The relatives of the patient and the health center were contacted by telephone to investigate the possibility of involvement of the relatives with whom he had traveled and lived in Morocco. Results: In a scenario with a low frequency of disease such as our country at the present time, family screening, after an initial diagnosis of imported brucellosis, allowed the detection and treatment of four members of the same family of Maghreb origin. They were infected during a trip to their place of origin in April 2019, a month in which they lived in rural areas in contact with animals (sheep, goats, cows) and consumed dairy and meat products. The appearance of presented symptoms was temporally consistent with the incubation period of the disease. Conclusions: Emphasize the importance of active surveillance and screening in relatives of patients diagnosed with Brucellosis, since they generally share exposures to a common source

Descripción de una nueva variante asociada a porfiria cutánea tarda

Poster [PC-093] La porfiria cutánea tarda (PCT) se debe a una alteración en la función de la enzima uroporfirógeno descarboxilasa, necesaria para la correcta síntesis del grupo hemo. Clínicamente, se caracteriza por fotosensibilidad y un cuadro de fragilidad cutánea que suele aparecer entre los 20 y los 40 años, siendo más frecuente en varones. También se asocia a afectación hepática. La PCT hereditaria es la responsable del 20% de los casos, causándola mutaciones en el gen UROD (MIM*613521) con un patrón autosómico dominante. El presente trabajo describe un paciente de 48 años sin antecedentes de hepatopatía crónica, enolismo o contacto con otros tóxicos, con erosiones dérmicas en zonas fotoexpuestas, hirsutismo malar y una concentración de uroporfirina en orina de 1.360, 97 mcg/24h. Concentración de hierro sérico, ferritina y enzimas hepáticas normales en sangre, VHB, VHC negativos, gen HFE normal. En resonancia magnética hepática se observa un incremento moderado (54mmol/g) en los depósitos de hierro. El análisis mediante secuenciación tipos “Sanger” del gen UROD completo detecta tres variantes, una de ellas con baja frecuencia poblacional y sin efecto descrito. Se ha analizado la presencia de esta variante en 21 sujetos control de población ibérica, no observándose en ninguno de ellos. Además, se ha analiza su efecto mediante 5 predictores bioinformáticos, indicando todos ellos que puede tratarse de una variante asociada a patogenicidad. El estudio en familiares de primer grado indica que un hijo del caso índice también presenta la variante. Los resultados del estudio, así como la baja frecuencia poblacional y las manifestaciones clínicas del paciente nos llevan a la conclusión de que esta variante, cuyo efecto no se conocía, se asocia a la porfiria cutánea tarda hereditaria. El hijo del caso presentado es un varón joven que puede no haber desarrollado todavía la sintomatología

X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern

Synthesis, spectroscopic properties and crystal structure of mononuclear tricarbonylrhenium(I) chloride complexes carrying 6-functionalised quinoxalines

Two quinoxaline derivatives pqCH3 and pqCl (where pq stands for 2-(2′-pyridyl)quinoxaline) were prepared by condensation of 2-acetyl pyridyl with 2-amino-4-methylphenylamine or 2-amino-4-chlorophenylamine, correspondingly and were studied spectroscopically and electrochemically, in correlation with the originally reported pq. Their novel corresponded complexes namely, fac-[Re(CO)3Cl(L)] (where L = pqCH3 2 and pqCl 3) were synthesized, characterized, studied and compared to Re(CO)3Clpq, 1. Complex 2 crystallizes in space group C2/c with a = 20.4476(17) Å, b = 15.4521(13) Å, c = 15.2887(13) Å, β = 126.1210(11)°, Z = 8 and V = 3902.0(6) Å3. The substitution of -H by -CH3 or -Cl at 6-position of pq has a minor electronic effect on the pyridyl ring of the ligands, but seems to influence the quinoxaline moiety enough to alter the spectroscopical and electrochemical features. © 2008 Elsevier B.V. All rights reserved

Isolation, X-ray structure and properties of an unusual pentacarbonyl(2,2′-pyridyl-quinoxaline) tungsten complex

The first example of a monodentate complexation of 2-(2′-pyridyl)quinoxaline (pq) to a metal centre through N4 is reported. Photochemical exchange of the THF ligand in W(CO)5THF by pq yields W(CO)5(N4-pq) (1), where the potentially bidentate pq ligand coordinates in an unusual monodentate fashion. Complex 1 is isolated as orange crystals and fully characterized on the basis of NMR, IR, UV-Vis and emission spectroscopy. The structure of 1 was determined by X-ray analysis. W(CO)5(N4-pq) (1) crystallizes in space group P21/n, monoclinic crystal system with α = 7.0237(5) Å, b = 10.4618(8) Å, c = 23.7768(18) Å, Z = 4 and V = 1731.9(2) Å3. Complex 1 exhibits intramolecular CH⋯N and intermolecular CH⋯O hydrogen bonds between the CH groups and nitrogen atoms of quinoxaline and CH groups and oxygen atoms of carbonyls, respectively, resulting in a supramolecular architecture in solid state. The preference to N4 as coordination site is discussed in terms of electronic interactions. Solutions of 1 emits dually at 77 K while they are moderately instable at room temperature, as 1 undergoes chelation via a first-order kinetic process to form W(CO)4pq (2). The determined reaction rate of 1 in toluene is 2.3 × 10-5 s-1 (at 298 K) and is compared with literature values for other W(CO)5L (L:diimine) complexes. © 2006 Elsevier B.V. All rights reserved

Preparation and x-ray structure of a rhodium(III)-rhodium(I) pyrazolate complex with a mercury atom asymmetrically bridging the metal atoms

Reaction of [Rh2(-pz)2(CO)2(PPh 3)2] (1) (pz = pyrazolate) with HgCl2 gives [(Ph3P)(CO)ClRh(-HgCl)(-pz)2Rh(CO)-(PPh 3)] (2); the X-ray stucture of (2) shows the presence of two rhodium atoms in different oxidation states asymmetrically bridged by a mercury atom, so that a unique RhIII-HgRhI fragment is present

Dinuclear rhodium-rhodium and rhodium-palladium complexes with different bridging ligands. Crystal structure of [Rh2(μ-SPPh2)(μ-Cl)(COD)2]

Homo- and hetero-dinuclear complexes of general formulae [Rh2(-SPPh2)(-Cl)(dìolefin)2] (diolefin = 1,5-cyclooctadiene (COD) (1), tetrafluorobenzobarrelene (TFB) (2)) and [RhPd(-SPPh2)(-Cl)(diolefin)(3-C3H5)] (diolefin = COD (4), 2,5-norbornadiene (NBD) (5)), containing one chloride anion and one thiophosphinito group as bridging ligands, have been synthesised by redistribution reactions starting from the corresponding homo-bridged compounds [Rh2(-SPPh2)2(diolefin)2], [Rh2(-Cl)2(diolefin)2] or [Pd2(-Cl)2(3-C3H5)2]. The structural X-ray analysis carried out for one member of this series, [Rh2(-SPPh2)(-Cl)(COD)2], has shown the bridging P,S-coordination of the thiophosphinito ligand. The intermetallic separation, 3.291(2) Å, excludes any significant direct metal-metal interaction