Synthesis and characterization of the macrocyclic complexes [Ni(Me2[14]dienatoN2P2)]PF6 and [Ni(Me2[16]dieneN2P2)](PF6) 2. Crystal structure of [Ni(Me2[16]dieneN2P2)](PF6) 2·0.5H2O

Article abstract of DOI:10.1021/ic00133a067

The titled macrocyclic complexes were synthesized by acid-catalyzed rearrangement of sexidentate phosphine amino Schiff base Ni(II) complexes prepared from 1 equiv of Ni(OAc)₂·4H₂O and bis(acetylacetone) trimethylenebis[(3-amino-propyl)phenylphosphine] or bis(acetylacetone) trimethylenebis[(2-aminoethyl)phenylphosphine]. Ring closure was accomplished in a mixture of water and acetic acid at pH 4 and results in the elimination of 1 equiv of Hacac. Infrared, visible spectra, and magnetic susceptibility measurements indicate that the complexes contain square-planar, diamagnetic Ni(II) bonded to a macrocyclic diphosphine-diimine ligand. Proton and ³¹P{¹H} NMR data suggest that the products are isomerically pure in either the meso or the racemic forms. The meso structure has been confirmed by single-crystal X-ray diffraction analysis of the 16-membered ring diene complex. This complex crystallizes in the monoclinic space group P2₁/c, with a = 14.049 (12) A?, b = 12.367 (8) A?, c = 20.129 (9) A?, and β = 105.11 (5)° at T = 20 (1)°C, λ = 0.71069 A? (Mo Kα radiation), and Z = 4. Least-squares refinement on F using 2230 unique reflections yielded a conventional R factor of 0.076. The two phosphorus and the two nitrogen atoms form a well-defined plane with the nickel atom lying 0.07 A? out of the plane (Ni-P = 2.182 (3) and 2.188 (4) A?; Ni-N = 1.916 (9) and 1.918 (8) A?; C=N = 1.29 (2) A?). The diimine ring exists in the boat conformation with the N=C bonds orientated at a 46° angle with respect to the N₂P₂ plane.