Copper complexes of arylselenolate-based ligands: synthesis and catalytic activity in azide-alkyne cycloaddition reactions

Abstract

[CuCl2(PPh3)2] reacts with the sodium salt of arylselenolates to yield tetrahedral [CuCl(SeAr)(PPh3)2] ((Ar = Ph, 1a; C5H4N, 1b; C4H(4,6-Me)2N2), 1c). During crystallization, the pyridyl nitrogens of the latter complexes 1b and 1c were protonated. However, the similar reaction with CuCl2·2H2O resulted in the formation of the polymeric complex of composition [Cu(SeAr)2]n (Ar = Ph, 2a; C5H4N, 2b). The latter complex 2b yielded the mono nuclear [CuCl(SeC5H4N)(PPh3)2] (1b) on treatment with excess phosphine. All complexes were characterized by elemental analysis, 1H NMR, IR and mass spectroscopy. The molecular structure of [CuCl(SeC5H4N+H)(PPh3)2] (1b′) was investigated by single crystal X-ray diffraction analysis. The copper(II) complexes of arylselenolates efficiently catalyzed azide–alkyne cyclo-addition reactions (click reactions) in water to give 1,4-substituted 1,2,3-triazoles in good to moderate yields.