THE METAL PROMOTED HYDRATION OF DI-2-PYRIDYL KETONE - UV-VIS SPECTRA OF CU(II) AND CR(III) IN AQUEOUS-SOLUTION WITH DI-2-PYRIDYL KETONE AND THE X-RAY STRUCTURE-ANALYSIS OF BIS-2,2',N,N'-BIPYRIDYL KETONE HYDRATE CHROMIUM(III) CHLORIDE AND RUTHENIUM

The crystal structures of the bipyridyl ketone hydrate complexes I, CrC22H26N4O8Cl and II, RuC22H34N4O12 have been determined by X-ray methods. Crystal data are: I, monoclinic space group C2/c, Z=4, a=11.19(1), b=14.67(1), c=17.12(1) Å, β=104.06(1)°; II, triclinic space group P1, Z=1, a=9.829(9), b=8.829(9), c=8.908(7) Å, α=99.79(6), β=103.04(6), γ=76.30(7)°. In both cases hydration occurs across the ketone double bond in the ligand and one of the hydrate oxygen atoms bonds to the metal to form a tridentate chelate. UV-Vis spectra of solutions of Cu(II) and Cr(III) with bipyridyl ketone, BPK, reveal that initial coordination of BPK and the metal is rapid but that weeks are required to form the complex compounds that crystallize from solution. The absorption spectra are shown to be pH dependent. The metal to ligand bond distances are I, CrO 1.939(5), CrN 2.061(5), 2.055(6) Å; II, RuO 1.975(4), RuN 2.057(4), 2.065(5) Å. An approximate correlation between off-axis angles of the coordinated oxygen atoms and the difference between square planar and octahedral crystal field stabilization energy in ten reported BPK hydrate complexes is indicated. © 1990.