The chemistry of copper(I) β-diketonate compounds. Part V. Syntheses and characterization of (β-diketonate)CuL<sub><i>n</i></sub> species where L = PBu<sub>3</sub>, PPh<sub>3</sub>, and PCy<sub>3</sub>; <i>n</i> = 1 and 2; crystal and molecular structures of (acac)Cu(PCy<sub>3</sub>), (tfac)Cu(PCy<sub>3</sub>), (hfac)Cu(PCy<sub>3</sub>), and (hfac)Cu(PCy<sub>3</sub>)<sub>2</sub> (1992)

The compounds (β-diketonate)Cu(PR 3 ) n , where β-diketonate = 1,1,1,5,5,5-hexafluoroacetylacetonate, hfac; 1,1,1-trifluoroacetylacetonate, tfac; and acetylacetonate, acac; R = n-butyl (n-Bu), phenyl (Ph), and cyclohexyl (Cy); n = 1 and 2, have been prepared. The monotriorganophosphine adducts were prepared in high yield by the reaction of the sodium salt of the corresponding β-diketonate with [ClCu(PR 3 )] with elimination of sodium chloride. The bis(triorganophosphine) adducts were prepared by the reaction of (β-diketonate)Cu(PR 3 ) with one equivalent of triorganophosphine. These species were characterized by 1 H, 13 C, and 31 P NMR spectroscopy, FTIR spectroscopy, mass spectroscopy, and by combustion elemental analysis. Four examples were structurally characterized by single crystal X-ray diffraction in the solid state. (acac)CuPCy 3 crystallizes in the triclinic crystal system, space group [Formula: see text], where a = 13.502(6) Ǻ, b = 13.691(6) Ǻ, c = 5.781(6) Ǻ, α = 71.05(3)°, β = 67.50(3)°, γ = 64.81(3)°, Z = 4, and R = 5.42%. (tfac)CuPCy 3 crystallizes in the monoclinic crystal system, space group P2 1 /n, where a = 9.639(3) Ǻ, b = 22.717(7) Ǻ, c = 12.045(5) Ǻ, β = 111.67(3)°, Z = 4, and R = 7.22%. (hfac)CuPCy 3 crystallizes in the monoclinic crystal system, space group P2 1 /c, where a = 9.870(2) Ǻ, b = 17.314(4) Ǻ, c = 15.586(3) Ǻ, β = 99.74(2)°, Z = 4, and R = 5.29%. (hfac)Cu(PCy 3 ) 2 crystallizes in the monoclinic crystal system, space group P2 1 /n, where a = 13.645(6) Ǻ, b = 19.252(13) Ǻ, c = 16.875(9) Ǻ, β = 102.02(4)°, Z = 4, and R = 7.20%. The compounds (β-diketonate)Cu(PCy 3 ) are all monomeric in the solid state and possess approximately trigonal-planar copper coordination environments, although (tfac)Cu(PCy 3 ) is significantly distorted from trigonal geometry. The Cu—O bond distances are significantly different in this species. The compound (hfac)Cu(PCy 3 ) 2 is monomeric in the solid state and possesses a distorted tetrahedral copper coordination environment. The distortion is believed to be due to the large steric demands of the PCy 3 ligands that result in long Cu—P bond distances of 2.251(3) and 2.277(3) Ǻ, a large P—Cu—P angle of 141.3(1)°, long Cu—O distances of 2.213(5) and 2.251(5) Ǻ, and a small O—Cu—O angle of 80.8(2)° compared to the corresponding values for (hfac)Cu(PCy 3 ). No trends in Cu—O bond distances between the compounds can be discerned, within the limits of error on the data, that would clearly enable a comparison of thermodynamic parameters such as bond length – bond strength relationships as a function of the β-diketonate substituents. However, the spectroscopic data revealed a number of trends as a function of the β-diketonate substituents, including an increase of ν(C=O and ν(C=C) in the order acac < tfac < hfac, analogous to the increase in their Lewis acidity. An increase in shielding of the 31 P resonance of the triorganophosphine ligands was observed in the order hfac < tfac < acac, consistent with expected inductive effects based on the electronegativity of the β-diketonate substituents.