NUCLEOPHILIC-ADDITION OF WATER AND ETHANOL TO COORDINATED DI-(2-PYRIDYL)KETONE IN RHENIUM(V) AND TECHNETIUM(V) COMPLEXES - THE CRYSTAL-STRUCTURE OF DICHLORO(HYDROXY-DI-(2-PYRIDYL)METHOXIDE)OXORHENIUM(V)

Complexes of general formula MOCl2[(C5H4N)2C(O)(OR)] (M = Re, Tc; R = H, Et) were prepared by the reaction of trans-ReOCl3(PPh3)2 and (n-Bu4N)[TcOCl4] with di-(2-pyridyl)ketone (DPK) in ethanol (R = Et) under nitrogen and in benzene, containing trace amounts of water, in air (R = H). The compounds were characterized by elemental analysis, vibrational, optical and proton nuclear magnetic resonance spectroscopy. The evidence suggests that the coordinated DPK ligand has undergone addition of water and ethanol at the carbonylic carbon atom, and that the (C5H4N)2C(O)(OR) moiety acts as a uninegative, terdentate N,O,N-donor ligand. The X-ray crystal structure of the complex ReOCl2[(C5H4N)2C(O)(OH)] is also reported. Crystal data: C11H9N2O3Cl2Re, orthorhombic, space group Pcca; a = 14.935(5), b = 11.896(8), c = 14.937(11) angstrom, and U = 2653.8 (2.7) angstrom3 to give Z = 8 for D(calc) = 2.37 g cm-3. The structure was solved by Patterson and Fourier methods and refined by least-squares methods to R = 0.076. The complex has an Re=O bond distance of 1.67(2) angstrom, and a deprotonated diolate oxygen of the ligand is coordinated in the position trans to the oxo group.