Perfluoropyridine as an Efficient, Tunable Scaffold for Bis(pyrazol‐1‐yl)pyridine Copper Complexes

Abstract

This report details the syntheses of five new 2,6bis(pyrazol-1-yl)pyridine ligands carried out by a unique strategy of utilizing pentafluoropyridine for the pyridine core. Formation of each ligand is accomplished under mild conditions utilizing carbonate bases. Each ligand reacts readily with copper(II) triflate to form the corresponding salt in high yield. Ligands and complexes were characterized by a combination of multi-nuclear NMR, FTIR, UV/Vis, and single-crystal X-ray diffrac- [a] Scheme 1. Synthetic strategies for bis(pyrazol-1-yl)pyridine ligands.

Toward Taming the Chemical Reversibility of Perfluoropyridine through Molecular Design with Applications to Pre- and Postmodifiable Polymer Architectures

“…While most of our molecular weights were consistent with a chain-growth mechanism, our Đ ’s were large relative to what is normally obtained for ROMP chain-growth polymerizations as shown in Table (for poly1 systems) and Table (for poly3 systems). While we are uncertain of the exact cause of these relatively high Đ ’s, this behavior was attributed to the potential coordination of the fluoropyridine ring to the ruthenium catalyst during the initiation step allowing the propagation step to progress significantly before the initiation step could go to completion, a factor that is well known to cause relatively high Đ ’s in chain-growth processes. − Previous work has demonstrated that the nitrogen of the fluoropyridine ring can participate in metal coordination making this a plausible, possible explanation . Postmodification of poly1 was carried out exclusively in THF with the exception of the installations of 4-nitrophenol and propargyl alcohol which required DMF to be used as the solvent.…”

“…18−20 Previous work has demonstrated that the nitrogen of the fluoropyridine ring can participate in metal coordination making this a plausible, possible explanation. 21 Postmodification of poly1 was carried out exclusively in THF with the exception of the installations of 4-nitrophenol and propargyl alcohol which required DMF to be used as the solvent. Analysis of both premodified and postmodified polymers via 1 H and 19 F NMR showed successful polymerization and successful incorporation of the desired functionalities.…”

Synthesis, Characterization, and Thermal Properties of Fluoropyridyl-Functionalized Siloxanes of Diverse Polymeric Architectures

“…Chemicals and solvents, which were of reagent grade, were purchased through commercial suppliers and used as received, unless specifically noted. The synthesis of 5 , 7 , and 8 was carried out from previously published work. , …”

“…The synthesis of 5, 7, and 8 was carried out from previously published work. 31,34 Instrumentation. 1 H, 13 C, and 19 F NMR spectra were recorded on a JEOL 500 MHz spectrometer.…”

“…Perfluoroaromatics (PFAr’s) have proven to be highly advantageous synthetic building blocks for diversifying polymeric materials, attributable to predictable nucleophilic substitution patterns and a range of nucleophile tolerability . Additionally, the high fluorine content in conjunction with aromaticity imparted to polymers derived from PFAr’s endows these materials with exceptional thermal stability and processability. , Of the many PFAr’s, perfluoropyridine (PFP) has proven to be an auspicious scaffold for fluoropolymer design, owing to its predictable and discrete regio-selective substitution pattern at the 2-, 4-, and 6-positions on the ring, its predilection for chemo-selective nucleophilic aromatic substitution, and its wide scope of nucleophile permissibility. − These properties permit facile incorporation of PFP into novel polymer architectures, allowing for diverse and tailorable material properties. − As shown in Scheme , PFP ( 1 ) offers unique opportunities to design linear ( via diene monomers ) and network ( from triene monomers ) polymers in addition to tailoring pre-functionalized monomers and post-polymerization modification. The research herein describes these applications of the modular PFP scaffold for use in semi-fluorinated silicone oils and elastomers utilizing hydrosilylation chemistry.…”