Tri- and tetracoordinate copper(i) complexes bearing bidentate soft/hard SN and SeN ligands based on 2-aminopyridine

Abstract

The coordination properties of the EN ligands N-(2-pyridinyl)amino-diphenylphosphine sulfide, N-(2-pyridinyl)amino-diisopropylphosphine sulfide, N-(2-pyridinyl)amino-diphenylphosphine selenide, N-(2-pyridinyl)amino-diisopropylphosphine selenide towards copper(I) precursors CuX (X = Br, I), [Cu(IPr)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), and [Cu(CH₃CN)₄]PF₆ were studied. Treatment of CuX with EN ligands resulted in the formation of tricoordinate complexes of the type [Cu(κ²(E,N)-EN)X]. The reaction of [Cu(IPr)Cl] with EN ligands, followed by halide abstraction with AgSbF₆, afforded cationic tricoordinate complexes [Cu(κ²(S,N)-EN)(IPr)]⁺, while the reaction of [Cu(CH₃CN)₄]⁺ with two equivalents of EN ligands yielded tetrahedral complexes [Cu(κ²(E,N)-EN)₂]⁺. Halide removal from [Cu(κ²(S,N)-SN)I] with silver salts in the presence of L = CH₃CN and CNtBu afforded dinuclear complexes of the type [Cu(κ²(S,N),μ(S)-SN)(L)]₂²⁺ containing bridging SN ligands. With the terminal alkynes HCCC₆H₄Me and HCCC₆H₄OMe, complexes of the formula [Cu(κ²(S,N)-SN-iPr)(η²-HCCC₆H₄Me)]⁺ and [Cu(κ²(S,N)-SN-iPr)(η²-HCCC₆H₄OMe)]⁺ were obtained. The mononuclear nature of these compounds was supported by DFT calculations. Most complexes were also characterized by X-ray crystallography.