Complexes of Di-2-pyridyl ketone. II. Some chelated nickel(II) products of metal-promoted reactions at the ketones

Abstract

From reactions in aqueous solution between nickel(11) nitrate, di-2-pyridyl ketone (DPK), and the reagents MeNH2, NH3, pyrazole ( C3H4N2) , HS03-,PhNHNH2, and 82-, solid complexes with the following stoicheiometries were isolated: Ni(DPK)z(MeNH2)2(N03)z(H2O)x (x: = 1, 0), Ni(DPK)z(NH~)(H2O)(NO3)3, K~(DPK)z(C3H4NZ)2(NO3)Z(H2O)y(y = 3, O), Ni(DPK)Z(HSO4)Z(HZO), Ni(DPK)2- (PhNHNH2)2(N03)2, and Ni(DPK)2(H2O)2S. Magnetic and spectral data indicate pseudo-octahedral ligand fields in all cases. Except in the cases Ni(DPK)2(H20)2S and Ni(DPK)2(PhNHNH2)2(NO3)2, for which the evidence is ambiguous, elementary compositions and i.r. spectra indicate that the added nucleophile, HX, has condensed with at least one of the two DPK units per nickel ion, yielding tridentate products, (C5H4N)2(OH)X. I n the complexes of stoicheiometry Ni(DPK)2(C3H4N2)2(N03)2 and N~(DPK)z(M~NH~)z(NO~)Z both DPK units per nickel ion have condensed with the nucleophile yielding products bound to the cation as tridentate N3 ligands. U.V. spectral observations in aqueous solution indicate that with the reagents MeNH2, NH3, C ~ H ~ N Z , and HS03- attack upon DPK occurs slowly, if a t all, in the absence of nickel(11) a t room temperature, but in the presence of nickel(11) much more rapid condensation occurs. These reactions constitute new types of metal-ion promoted condensation. With cyanide ion as the nucleophile, attack occurs not a t the ketone but a t nickel yielding [Si(DPK)2]2+[Ni(CN)4]z- in w-hich the cation is octahedral, the anion square-planar, and some cyanide units are bridging.