13002-64-7Relevant academic research and scientific papers
cis-Octahedral nickel(II) complexes with symmetric and unsymmetric tripodal tetraamine ligands
Ochs, Christian,Hahn, F. Ekkehardt,Lugger, Thomas
, p. 1279 - 1285 (2001)
Nickel(II) complexes with the aliphatic tripodal tetraamine ligands N(CH2CH2NH2)3 (tren, 1), N[(CH2CH2CH2NH2)(CH 2CH2NH2)2] (baep, 2), N[(CH2CH2CH2NH2)2 -(CH2CH2NH2)] (abap, 3), and N(CH2CH2CH2NH2)3 (trpn, 4) are reported. The tripodal tetradentate N4 ligands 1-4 react with Ni(NO3)2·6H2O in acetonitrile or methanol to give the blue nickel(II) complexes [Ni(1)(η1-NO3)2] (5a), [Ni(2)(η1 NO3)2] (5b), [Ni(3)(η2-NO3)]NO3·CH 3CN (5c·CH3CN), and [Ni(4)(η2-NO3)]NO3·CH 3OH (5d·CH3OH). With NiCl2·6H2O, the complexes [Ni(1)Cl(H2O)]Cl·H2O (6a), [Ni(2)(μCl)2Ni(2)]Cl2·2CH3OH (6b·2CH3OH), [Ni(3)Cl(H2O)]Cl (6c), and [Ni(4)(H2O)2]Cl2·H2O (6d·H2O) are obtained. The molecular structures of complexes 5a-d and 6b-d have been determined by X-ray diffraction analysis and they are compared with the molecular structure of the previously characterized complex 6a. Complexes 5a-d and 6b-d exhibit octahedrally coordinated nickel atoms. The tripodal ligands occupy four of the six coordination sites in a pseudo-facial manner. Complexes of the unsymmetrical ligands 2 and 3 possess both five- and six-membered chelate rings. The extension of the ligand arms in 1-4 leads to a systematic variation in the geometric and UV/Vis spectroscopic properties of the complexes depending on the size of the chelate rings formed by the ligands.
Metal Ion Promoted Hydrolysis of Polyphosphates
Geue, Rodney J.,Sargeson, Alan M.,Wijesekera, Ramanee
, p. 1021 - 1040 (2007/10/02)
Various CoIII amine aqua hydroxo complexes have been evaluated for their ability to hydrolyse pyrophosphate to phosphate rapidly.Two very effective reagents have emerged, 2+ (trpn = 3,3',3"-nitrilotris(propan-1-amine)) and 2+ (tamen = 6-(4-amino-2-azabutyl)-6-methyl-1,4-diazacycloheptane), and the latter has been examined closely to assess details of the mechanistic path for hydrolysis.The study shows substitution of the reagent on the substrate is fast and not rate determining.Two moles of the reagent are required to bind to - (en = ethane-1,2-diamine) to effect rapid hydrolysis.One supplies the coordinated OH- nucleophile to cleave the phosphorus anhydride, and the other binds as a chelate to the leaving group to assist bond rupture.An unproductive side path, to form a symmetrical dichelate of the form 2+, becomes rate limiting.However, if this path can be reduced in significance or eliminated, the study implies that polyphosphates and phosphate esters should hydrolyse on the subsecond time scale.
