An Actinide Complex with a Nucleophilic Allenylidene Ligand.

The reaction of [Cp3Th(3,3-diphenylcyclopropenyl)] (Cp = η5-C5H5) with 1 equiv of lithium diisopropylamide (LDA) results in cyclopropenyl ring opening and formation of the thorium allenylidene complex, [Li(Et2O)2][Cp3Th(CCCPh2)] ([Li(Et2O)2][1]), in good yield. Additionally, deprotonation of [Cp3Th(3,3-diphenylcyclopropenyl)] with 1 equiv of LDA, in the presence of 12-crown-4 or 2.2.2-cryptand, results in the formation of discrete cation/anion pairs, [Li(12-crown-4)(THF)][Cp3Th(CCCPh2)] ([Li(12-crown-4)(THF)][1]) and [Li(2.2.2-cryptand)][Cp3Th(CCCPh2)] ([Li(2.2.2-cryptand)][1]), respectively. Interestingly, the complex [Li(Et2O)2][1] undergoes dimerization upon standing at room temperature, resulting in the formation of [Cp2Th(µ:η1:η3-CCCPh2)]2 (2), via loss of LiCp. The reaction of [Li(Et2O)2][1] with MeI results in electrophilic attack at the Cγ carbon atom, leading to the formation of a thorium acetylide complex, [Cp3Th(C≡CC(Me)Ph2)] (3), which can be isolated in 83% yield upon workup, whereas the reaction of [Li(Et2O)2][1] with benzophenone results in the formation of 1,1,4,4-tetraphenylbutatriene (4) in 99% yield, according to integration against an internal standard. Density functional theory (DFT) calculations performed on [1]- and 2 reveal significant electron delocalization across the allenylidene ligand. Additionally, calculations of the 13C NMR chemical shifts for the Cα, Cß, and Cγ nuclei of the allenylidene ligand were in good agreement with the experimental shifts. The calculations reveal modest deshielding induced by spin-orbital effects originating at Th due to the involvement of the 5f orbitals in the Th-C bonds. According to a DFT analysis, the cyclopropenyl ring-opening reaction proceeds via [Cp3Th(η1-3,3-Ph2-cyclo-C3)]- (IM), which features a carbanion character at Cß.

Quantifying Actinide-Carbon Bond Covalency in a Uranyl-Aryl Complex Utilizing Solution 13C NMR Spectroscopy.

Reaction of [UO2Cl2(THF)2]2 with in situ generated LiFmes (FmesH = 1,3,5-(CF3)3C6H3) in Et2O resulted in the formation of the uranyl aryl complexes [Li(THF)3][UO2(Fmes)3] ([Li(THF)3][1]) and [Li(Et2O)3(THF)][UO2(Fmes)3] ([Li(Et2O)3(THF)][1]) in good to moderate yields after crystallization from hexanes and Et2O, respectively. Both complexes were characterized by X-ray crystallography and NMR spectroscopy. DFT calculations reveal that the Cispo resonance in [1]- exhibits a deshielding of 51 ppm from spin-orbit coupling effects originating at uranium, which indicates an appreciable covalency in the U-C bonding interaction.

Assessing the 4f Orbital Participation in the Ln-C Bonds of [Li(THF)4][Ln(C6Cl5)4] (Ln = La, Ce).

The reaction of [Ln(NO3)3(THF)4] (Ln = La, Ce) with 4 equiv of LiC6Cl5 in Et2O resulted in the formation of the homoleptic lanthanide-aryl "ate" complexes [Li(THF)4][La(C6Cl5)4] ([Li][1]) and [Li(THF)4][Ce(C6Cl5)4] ([Li][2]). These complexes represent the first isolated homoleptic perchlorophenyl complexes for the lanthanides. In the solid state, both [Li][1] and [Li][2] exhibit octa-coordinate lanthanide centers, with four Ln-C σ-bonds and four Cl → Ln dative interactions involving the ortho-Cl atoms of the C6Cl5 ligands. Despite this apparent steric saturation, both [Li][1] and [Li][2] are highly temperature sensitive and quickly decompose in solution at room temperature. Density functional calculations show that the Ln-Cipso donation bonds feature only weak 4f participation (e.g., ∼1% 4f weight for [1]-). Nonetheless, the 13C chemical shift of the Cipso nuclei of [1]- includes ca. 8 ppm of deshielding from the spin-orbit interaction due to the participation of the 4f (and 5d) orbitals in the La-C bonds.

Synthesis and Characterization of Two Uranyl-Aryl "Ate" Complexes.

Reaction of [UO2 Cl2 (THF)3 ] with 3 equivalents of LiC6 Cl5 in Et2 O resulted in the formation of first uranyl aryl complex [Li(Et2 O)2 (THF)][UO2 (C6 Cl5 )3 ] ([Li][1]) in good yields. Subsequent dissolution of [Li][1] in THF resulted in conversion into [Li(THF)4 ][UO2 (C6 Cl5 )3 (THF)] ([Li][2]), also in good yields. DFT calculations reveal that the U-C bonds in [Li][1] and [Li][2] exhibit appreciable covalency. Additionally, the 13 C NMR chemical shifts for their Cipso environments are strongly affected by spin-orbit coupling-a consequence of 5f orbital participation in the U-C bonds.

Homoleptic Perchlorophenyl "Ate" Complexes of Thorium(IV) and Uranium(IV).

The reaction of AnCl4(DME)n (An = Th, n = 2; U, n = 0) with 5 equiv of LiC6Cl5 in Et2O resulted in the formation of homoleptic actinide-aryl "ate" complexes [Li(DME)2(Et2O)]2[Li(DME)2][Th(C6Cl5)5]3 ([Li][1]) and [Li(Et2O)4][U(C6Cl5)5] ([Li][2]). Similarly, the reaction of AnCl4(DME)n (An = Th, n = 2; U, n = 0) with 3 equiv of LiC6Cl5 in Et2O resulted in the formation of heteroleptic actinide-aryl "ate" complexes [Li(DME)2(Et2O)][Li(Et2O)2][ThCl3(C6Cl5)3] ([Li][3]) and [Li(Et2O)3][UCl2(C6Cl5)3] ([Li][4]). Density functional calculations show that the An-Cipso σ-bonds are considerably more covalent for the uranium complexes vs the thorium analogues, in line with past results. Additionally, good agreement between experiment and calculations is obtained for the 13Cipso NMR chemical shifts in [Li][1] and [Li][3]. The calculations demonstrate a deshielding by ca. 29 ppm from spin-orbit coupling effects originating at Th, which is a direct consequence of 5f orbital participation in the Th-C bonds.

Quistes y tumores de la laringe / Cysts and tumors of the larynx

Los quistes de la laringe son lesiones benignas que por lo general se tratan con facilidad. El tratamiento de estos quistes saculares en general se realiza a través de laringoscopia directa. En la clasificación se identifican quistes saculares, ductales, laringoceles se describe la fisiopatalogía y las manifestaciones clínicas.

Proptosis unilateral indolora / Painless unilateral proptosis

Se presenta el caso de una paciente de 68 años con proptosis unilateral no doloroso de dos años de evolución. Se realizó el diagnóstico de Linfoma No Hodgkin tipo B. El paciente recibió tratamiento con quimioterapia sistémica y consolidación con radioterapia local con buena evolución.

Paratiroidectomía subtotal en pacientes con insuficiencia renal crónica / Subtotal parathyroidectomy in patients with chronic renal failure

Antecedentes: el hiperparatiroidismo es común en los pacientes con insuficiencia renal crónica. Entre el 5 y el 30 por ciento de los dializados crónicos desarrollarán síntomas severos secundarios al hiperparatiroidismo, por lo general refractarios a la terapéutica médica. En estos casos está indicado el tratamiento quirúrgico. Objetivo: evaluar resultados obtenidos en pacientes portadores de hiperparatiroidismo secundario tratados con paratiroidectomía subtotal. Lugar de aplicación: hospital polivalente de alta complejidad. Diseño: restrospectivo. Población: 50 pacientes, (edad promedio 43 años) intervenidos quirúrgicamente entre octubre de 1999 y abril de 2003. Métodos: paratiroidectomía total en todos los casos. Resultado: la mejoría clínica general obtenida con esta técnica fue del 92,5 por ciento, y el 68 por ciento de los pacientes se encuentran en normo función endocrina, de acuerdo a la determinación del PTHi. El tiempo de seguimiento promedio fue de 15,2 meses, la morbilidad del 8 por ciento y sin mortalidad. Conclusiones: la paratiroidectomía subtotal proporciona un buen control de hiperparatiroidismo secundario a insuficiencia renal crónica. Los resultados a largo plazo serán analizados en un período de tiempo suficiente adaptando esta técnica específica a nuestro sistema de salud