Structural diversity of copper(i)–ethylene complexes with 2,4-bis(2-pyridyl)pyrimidine directed by anions

Abstract

The 3 : 1 reaction of [Cu(C₂H₄)_n]ClO₄ with 2,4-bis(2-pyridyl)pyrimidine (bpprd) in Me₂CO under C₂H₄ afforded yellow prism crystals of the dinuclear Cu(I)–C₂H₄ complex [Cu₂(bpprd)(η²-C₂H₄)₂(ClO₄)₂] (1). The 3 : 1 reaction of [Cu(C₂H₄)_n]NO₃ with bpprd in Me₂CO under C₂H₄ afforded yellow plate crystals of the tetranuclear Cu(I)–C₂H₄ complex [Cu₄(bpprd)₂(η²-C₂H₄)₄(μ-NO₃)₂](NO₃)₂ (2). The 10 : 1 reaction of [Cu(C₂H₄)_n]BF₄ with bpprd in Me₂CO under C₂H₄ afforded yellow plate crystals of the dinuclear Cu(I)–C₂H₄ complex [Cu₂(bpprd)(η²-C₂H₄)₂(BF₄)]BF₄ (3). The 3 : 1 reaction of [Cu(C₂H₄)_n]BF₄ with bpprd in Me₂CO under C₂H₄ afforded red prism crystals of the polymeric Cu(I)–C₂H₄ complex {[Cu₆(bpprd)₄(η²-C₂H₄)₂(μ–η²:η²-C₂H₄)(μ-BF₄)₂](BF₄)₄}_n (4). The X-ray crystal structures of complexes 1–4 have been determined. The structural diversity of Cu(I)–C₂H₄ complexes bridged by bpprd with different anions was demonstrated. The 1D Cu(I)–bpprd/C₂H₄ coordination polymer 4 bridged by unusual μ–η²:η²-C₂H₄ and the μ-BF₄⁻ anion is of particular significance. Complex 1 exhibited relatively well-resolved ¹H NMR signals of bpprd and C₂H₄ (δ = 4.97 ppm) in (CD₃)₂CO at 23 °C.