Csp³–Csp³ Bond-Forming Reductive Elimination from Well-Defined Copper(III) Complexes

Abstract

Carbon-carbon bond-forming reductive elimination from elusive organocopper(III) complexes has been considered the key step in many copper-catalyzed and organocuprate reactions. However, organocopper(III) complexes with well-defined structures that can undergo reductive elimination are extremely rare, especially for the formation of Csp 3-Csp 3 bonds. We report herein a general method for the synthesis of a series [alkyl-Cu III-(CF 3) 3 ]complexes, the structures of which have been unequivocally characterized by NMR, mass spectrometry and X-ray crystal diffraction. At elevated temperature, these complexes undergo reductive elimination following first-order kinetics, forming alky-CF 3 products with good yields (up to 91%). Both Kinetic studies and DFT calculations indicate that the reductive elimination to form Csp 3-CF 3 bonds proceeds through a concerted transition state, with a ΔH ‡ =20 kcal/mol barrier.

Photoinitiated Reactions of Haloperfluorocarbons with Gold(I) Organometallic Complexes: Perfluoroalkyl Gold(I) and Gold(III) Complexes

“…The (18);C Mes -Au-CF 2 89.21 (8),C Mes -Au-P 88.39 (6),C F 2 -Au-P 174.74 (6),C Mes -Au-I 178.53 (6), CF 2 -Au-I 91.90 (6), P-Au-I 90.573 (13). Figure 5.…”

“…Molecular structure of 10 in the solid state(50 %t hermal ellipsoids). Selectedbondlengths []a nd angles [8]: AuÀP2 .3781 (7), AuÀCF 2 2.118(3), AuÀC Mes 2.061(2), AuÀI2 .6777(3);C Mes -Au-CF 2 89.10(10), C Mes -Au-P 90.30 (7), CF 2 -Au-P 174.95 (7), C Mes -Au-I 175.60 (7), CF 2 -Au-I 91.65 (7), P-Au-I 89.329 (18). Figure 6.…”

“…[2o, 3] However,itisgenerally acceptedt hat perfluoroalkyl complexes present ar emarkable inertness against reductive elimination [4] and, consequently,avery limitedn umber of stoichiometric C-perfluoroalkyl bond-formingr eductive eliminations have been observed. Reported examples comprise aryltrifluoromethyl-Pd II complexes containing purposely designed ligands, [3c, j, 5] or alkyl-anda ryl-trifluoromethyl complexes of metals in high oxidation states, such as Pd IV , [6] Ni IV , [7] Cu III[3b,8] or Au III . [9] In contrastt ot he thoroughly studied trifluoromethyl complexes, metal complexes containing larger perfluoroalkyl ligands have received much less attention.…”

“…Crystal structureof1 in the solid state (50 %thermal ellipsoids). Selected bond lengths []a nd angles[8]: AuÀC2.097(2), AuÀP2 .2918(5); C-Au-P1 73.07(6).…”

“…Molecular structure of 2 in the solid state (50 %t hermal ellipsoids). Selected bondlengths []a nd angles[8]: AuÀC carbene 2.014(2),A u ÀCF 2.125(3);C carbene -Au-CF 175.89(10).…”