Mononuclear Hydroxamate Five-Coordinate Nickel(II) Complexes:  Structural and Spectroscopic Characterization

Abstract

Novel nickel complexes containing {O,O}-chelating hydroxamate ligands were prepared by attack of the hydroxamic acid by the hydroxo ligand, and the crystal structure shows the nickel atom in a five-coordinate environment that has structural features similar to those of inhibited urease.

Pentacoordinate Nickel(II) Complexes Double Bridged by Phosphate Ester or Phosphinate Ligands: Spectroscopic, Structural, Kinetic, and Magnetic Studies

“…As described in Scheme 1 c, the acid±base reaction provided higher yields (82±93 %) and could be applied to the synthesis of the phosphinate-bridged complexes [{Ni( [12] E(P) transitions, respectively. [12] Both l max values and molar absorptivities are consistent with a five-coordinate environment around the nickel(ii) ion, [13] and provide evidence that the molecule maintains its integrity in solution.…”

“…The IR spectra of complexes 1±12 show characteristic absorptions for the [12]aneN 3 ligands [13] : 3291±3258 cm À1 n(NÀH),~1660 cm À1 n(C=N), and two strong bands as a result of the PF 6 À ion at 840 and 560 cm…”

Synthesis and Characterization of Heterotrinuclear Complexes of Nickel and Palladium with Pyridinecarboxylate as Bridging Ligands

“…This synthetic method has previously been used for the preparation of pentacoordinate nickel(ii) complexes containing N,S-donor, [10] oxamidate, [11] hydroxamate, [12] and pyridonate ligands, [13] as well as phosphate esters and phosphinate derivatives. [14] Complexes 1-4 are air-stable both in the solid state and in solution.…”

“…They have been characterized by partial elemental analyses, FAB + mass spectrometry and spectroscopic (IR, UV/Vis, and 1 H NMR) methods. The IR spectra of complexes 1-4 show characteristic absorptions for the mcN 3 ligands: [12,14] 3287-3121 cm -1 for ν(N-H), ca. 1660 cm -1 for ν(C=N), and two strong bands as a result of the PF 6 -ion at 840 and 560 cm -1 .…”

Synthesis, structural characterisation and antibacterial activity of bis(1-phenyl-1,3-butanedionato)non-oxovanadium(IV) hydroxamates

“…Metal complexes of hydroxamic acids have also attracted considerable attention because of their tautomerisation [14] exhibiting hydroxamic or hydroximic acid forms. The theoretical and experimental studies have suggested that the hydroxamic form is prevalent in free acids [15] or metal hydroxamates [16]. Fewer studies have described vanadium (IV) and (V) hydroxamate complexes as compared to many other transition metal hydroxamates [17][18][19][20][21] whereas vanadyl sulphate, ammonium vanadate and vanadyl acetylacetonate have been exploited as precursors [22].…”