Reaction of Diphenylphosphanylacetylene with RB(C₆F₅)₂ Reagents: Evidence for a Remarkable Sequence of Synergistic Frustrated <i>Lewis</i> Pair Addition Reactions

Diphenylphosphanylethyne (<b>3a</b>) reacts with tris­(pentafluorophenyl)­borane at room temperature by a typical frustrated <i>Lewis</i> pair (FLP) reaction. It undergoes a sequential series of 1,2-phosphane/borane additions to the alkyne unit in an overall 2:2 molar ratio to selectively form the dimeric product <b>5a</b>. Product <b>5</b> features a pentafulvene-reminiscent structure with a pair of phosphonium units in the ring and B­(C₆F₅)₃ substituents at the periphery. At elevated temperature, the reaction becomes less selective, now favoring the formation of cis- and trans-1,1-carboboration products from a 1:1 stoichiometry. After photolytic trans/cis isomerization, the vicinal FLP <b>6a</b> becomes the major product, featuring an intramolecular P···B interaction. The reaction of <b>3a</b> with H₃CB­(C₆F₅)₂ also gives a heterocyclic dimer (<b>11</b>), except that here a substituent H/CH₃ exchange by an addition/elimination pathway has taken place. In the B­(C₆F₅)₃-derived system, we were able to trap an alleged intermediate of this rearrangement reaction by adding <i>n</i>-butyl isocyanide. Five products in the Ph₂P- and (<i>p</i>-tolyl)₂P-derived systems were characterized by X-ray diffractio

Video1_A comparative retrospective analysis: myocutaneous flap versus skin flap in V-Y medial epicanthal fold reconstruction.mp4

ObjectivesTo evaluate the comparation of myocutaneous flap vs. skin flap in V-Y medial epicanthal fold reconstruction.MethodsThe study, conducted from April 2017 to June 2022, involved two groups: group A, comprising 21 patients who underwent medial epicanthal fold restoration surgery using the V-Y advancement method with a skin flap, and group B, comprising 83 patients who underwent the same procedure, while with a myocutaneous flap for orbicularis oculi ring reconstruction. Intercanthal distances were measured preoperatively, recorded during preoperative and postoperative reviews, and assessed through a 4-point Likert satisfaction questionnaire.ResultsA total of 104 patients were followed up for 6 months postoperatively. In group A, preoperative intercanthal distances ranged from 28.7 mm to 38.2 mm, increasing to 30.2 mm–40.6 mm postoperatively, with a mean increase of 3.0 mm (P ConclusionThe myocutaneous flap V-Y procedure, employing the principle of orbicularis oculi ring reconstruction, achieves more stable postoperative results than the flap-only V-Y procedure. Consequently, it can be regarded as the preferred surgical technique.</p

Probing the Characteristics of Mono- or Bimetallic (Iron or Cobalt) Complexes Bearing 2,4-Bis(6-iminopyridin-2-yl)‑3<i>H</i>‑benzazepines: Synthesis, Characterization, and Ethylene Reactivity

A series of 2,4-bis­(6-iminopyridin-2-yl)-3<i>H</i>-benzazepines and the mono- or bimetallic (Fe²⁺ or Co²⁺) complexes thereof were synthesized and characterized. All title complexes, when activated by MAO or MMAO, exhibited high activities of up to 4.0 × 10⁷ g (mol of Fe)⁻¹ h^–1 for ethylene oligomerization and polymerization. The iron­(II) precatalysts generally showed higher activities and produced a wider distribution of products (including oligomers and polyethylene) than did their corresponding cobalt­(II) analogues. The bimetallic precatalysts exhibited higher (almost twice) activities in comparison to their monometallic analogues. The distribution of the resulting oligomers closely resembled the Schultz–Flory rule

Probing the Characteristics of Mono- or Bimetallic (Iron or Cobalt) Complexes Bearing 2,4-Bis(6-iminopyridin-2-yl)‑3<i>H</i>‑benzazepines: Synthesis, Characterization, and Ethylene Reactivity

A series of 2,4-bis­(6-iminopyridin-2-yl)-3<i>H</i>-benzazepines and the mono- or bimetallic (Fe²⁺ or Co²⁺) complexes thereof were synthesized and characterized. All title complexes, when activated by MAO or MMAO, exhibited high activities of up to 4.0 × 10⁷ g (mol of Fe)⁻¹ h^–1 for ethylene oligomerization and polymerization. The iron­(II) precatalysts generally showed higher activities and produced a wider distribution of products (including oligomers and polyethylene) than did their corresponding cobalt­(II) analogues. The bimetallic precatalysts exhibited higher (almost twice) activities in comparison to their monometallic analogues. The distribution of the resulting oligomers closely resembled the Schultz–Flory rule