A facile synthesis of metalla- octafluorocyclopentane complexes of ruthenium and nickel

Abstract

Reduction of the dihalogeno complexes RuCl,(PPh,), and NiBr,L, (L = tertiary phosphine) with sodium hydride in MeCN in the presence of tetrafluoroethylene gives complexes containing five-membered MC,F8 rings. 1,2-Dihydrotetrafluoroethane is a by-product of these syntheses, especially when hydrogen is added. The M--C bonds of the metalla-perfluorocyclopentane complexes are remarkably stable against hydrogenolysis.

Activation of C–F and Ni–C Bonds of [P,S]-Ligated Nickel Perfluorometallacycles

“…9 The reaction required elevated temperatures/pressures and hydrogenolysis of the typically robust Ni−R F bonds was only observed when π-acidic phosphite ligands were employed. 9,10 Catalysis with transitionmetal perfluoroalkyl intermediates is inherently challenging due to the general stability of M−R F (R F = fluoroalkyl) bonds, 11, The bis(phosphite)nickel perfluorometallacycle 1 was synthesized according to reported methods. 3,9 Treatment of 1 with the thiol form of the ligand, 1,2,4-(HS)(Ph 2 P)Me(C 6 H 3 ) (variation of the known ligand 1,2-(HS)(Ph 2 P)(C 6 H 4 )) 13 led to unexpected migration of an isopropyl group of the phosphite ligand to the sulfur atom of the ligand, cleanly yielding complex 2 (86% isolated yield).…”

“…Baker et al later developed a catalytic method for the hydrodimerization of TFE, with perfluoronickelacyclopentane and NiL 4 intermediates (Scheme ) . The reaction required elevated temperatures/pressures and hydrogenolysis of the typically robust Ni–R F bonds was only observed when π-acidic phosphite ligands were employed. , Catalysis with transition-metal perfluoroalkyl intermediates is inherently challenging due to the general stability of M–R F (R F = fluoroalkyl) bonds, , but a number of new metal-based methods for introducing R F (predominantly CF 3 ) groups to organic molecules have appeared recently …”

Mild, Safe, and Versatile Reagents for (CF2)n Transfer and the Construction of Fluoroalkyl-Containing Rings

“…54,55 To our knowledge, the synthetic routes to well-defined perfluorometallacyclopentanes all involve the oxidative coupling of TFE, as outlined in eq 1. 35,36,38,[42][43][44]46,49,52,53,56 This oxidative coupling reaction appears to be common for other late transition metals, as complexes 2−6 (Chart 1) are all formed upon reaction of an appropriate metal precursor with TFE. Such routes are problematic for discovery research today as TFE has become increasingly unavailable for purchase due to the explosion hazards associated with its handing.…”

“…The (CF 2 ) n functionality is also of interest to the synthetic organic and organometallic communities as it is the backbone of perfluoroalkyl-based metallacycles, the largest numbering class of which are the perfluorometallacyclopentanes. Perfluorometallacyclopentanes like those shown in Chart have been known since 1961. − Stone and co-workers prepared the first example ( 1 ) involving the reaction of iron pentacarbonyl with tetrafluoroethylene (TFE). They found that the resulting metallacycle was extraordinarily stable and failed to release carbon monoxide or fluorocarbon even after being treated with bromine for 60 h at 50 °C .…”

“…To our knowledge, the synthetic routes to well-defined perfluorometallacyclopentanes all involve the oxidative coupling of TFE, as outlined in eq . ,,,− ,,,,, This oxidative coupling reaction appears to be common for other late transition metals, as complexes 2 – 6 (Chart ) are all formed upon reaction of an appropriate metal precursor with TFE. Such routes are problematic for discovery research today as TFE has become increasingly unavailable for purchase due to the explosion hazards associated with its handing. − TFE can be prepared inexpensively on a reasonable scale from the thermal pyrolysis of waste polytetrafluoroethylene (PTFE), − but such routes typically involve temperatures above 600 °C and the use of a quartz furnace connected to a vacuum manifold.…”