Reactivity of Dinuclear Copper(I)/pybox Complexes towards Isocyanides and Phosphanes

Abstract

AbstractThe dinuclear complexes [Cu2(R‐pybox)2][PF6]2 {R‐pybox = 2,6‐bis[4′‐(S)‐isopropyloxazolin‐2′‐yl]pyridine for (S,S)‐iPr‐pybox (1) and 2,6‐bis[4′‐(R)‐phenyloxazolin‐2′‐yl]pyridine for (R,R)‐Ph‐pybox (2)} are very efficient precursors for the synthesis of dinuclear and mononuclear derivatives containing isocyanide or phosphane ligands. The reaction of 1 and 2 with the isocyanides (CNBn or CNCy) resulted in the synthesis of the dinuclear derivatives [Cu2(R‐pybox)2(CNBn)2][PF6]2 [R‐pybox = (S,S)‐iPr‐pybox (3), (R,R)‐Ph‐pybox (4)] and [Cu2(R‐pybox)2(CNCy)2][PF6]2 [R‐pybox = (S,S)‐iPr‐pybox (5), (R,R)‐Ph‐pybox (6)]. When the reaction was carried out with the monodentate (PMePh2, PPh3) and the bidentate phosphanes [dppm, dppf, (S)‐peap] the mononuclear complexes [Cu(R‐pybox)(PRPh2)2][PF6] [R‐pybox = (S,S)‐iPr‐pybox, R = Me(7), Ph (8); R‐pybox = (R,R)‐Ph‐pybox, R = Ph (9)], [Cu(R‐pybox){(S)‐peap}][PF6] [R‐pybox = (S,S)‐iPr‐pybox (11), (R,R)‐Ph‐pybox (12)], and [Cu(R‐pybox)(dppf)][PF6] [R‐pybox = (S,S)‐iPr‐pybox (13), (R,R)‐Ph‐pybox (14)] and the dinuclear complex [Cu2{(S,S)‐iPr‐pybox}(μ‐dppm)2][PF6]2 (10) were obtained, respectively. The structures of complexes 3, 7, 10, and 13 have been resolved by X‐ray diffraction methods and by 1D, 2D, and DOSY NMR spectroscopy measurements. The 1H, 31P, and 19F DOSY NMR spectroscopic experiments provided evidence that the solid‐state nuclearity of compounds 3, 7, 10, and 13 is maintained in solution and confirmed that these ionic compounds exist in solution as stable, discrete, cationic complexes.