Spectroscopic study and x-ray structure of bis(N-methylimidazole)bis(2,4,6, trichlorophenolato)cobalt(II)

Abstract

The preparation, spectroscopic study and X-ray structure of the mixed-valence compound Pt(NMIz) 4− PtCl 6 are described; NMIz stands for N-methyl-imidazole. The crystal and molecular structure has been determined by a single crystal X-ray analysis using three-dimensional diffractometer data. The compound crystallizes in the triclinic system, with four formula units in the unit cell, space group F 1 and lattice parameters a = 15.228(11), b = 17.855(12), c = 11.177(8) Å, α = 91.98(6), β = 106.94(6), γ = 115.76(7)°. The structure was solved and refined using the heavy-atom method and subsequent least-squares techniques. Refinements using 2335 observed reflections (Mo-Kα radiation) led to final values for R and R w of 0.077 and 0.075 respectively. The Pt(II) ions are surrounded in a square-planar geometry by four NMIz ligands (Pt−N = 1.986−2.012(14) Å and N−Pt−N = 92.6(6)°). Pt(IV) is octahedrally coordinated by the six Cl − ions (Pt−Cl = 2.313−2.323(6) and Cl−Pt−Cl = 88.3−89.9(2)°). In addition there is an interaction between the Pt(NMIz) 2+ 4 ions and the PtCl 2− 6 ions (with Pt⋯Cl = 3.538(5) Å and Pt(II)⋯Cl-Pt(IV) = 144.1°) and Pt(II). Pt(IV) = 5.588 Å), resulting in chain-type behaviour along the c-axis. Optical, infrared and far-infrared spectra agree with this structure. No clear intervalence charge-transfer absorption could be detected which might be related to the relatively long Pt(II)⋯Pt(IV) distance in this compound.