Kinetics of Dissociation of tris-{3-(2-pyridyl)-5,6-bis(2-furyl)-1,2,4-triazine}iron(II)

Abstract

The kinetics of base hydrolysis of the low-spin iron(II)-diimine complex [Fe(fertri) 3 ] 2+ , where fertri=3-(2-pyridyl)-5,6-bis(2-furyl)-1,2,4-triazine, as a function of hydroxide concentration, solvent composition (water; aqueous MeOH), and pressure are reported. Rate constants are also reported for dissociation of the [Fe(fertri) 3 ] 2+ cation in 50-64% MeOH, determined from replacement of the fertri ligands by 1,10-phenanthroline. The reactivity of this fertri complex is compared with reactivities of a selection of other iron(II)-diimine complexes and, where possible, their ligand-sulfonated derivatives. The activation volume for base hydrolysis of [Fe(fertri) 3 ] 2+ is +10.7 cm 3 mol )1 , in 40% MeOH.

Kinetics and mechanism of substitution of bis(2,4,6-tripyridyl 1,3,5-triazine)iron(II) by 2,2′,6,2″-terpyridine

“…Furthermore, the log b value for the intermediate ternary complex, 15.74, which is greater than that for Fe(TPTZ) 2þ 2 and less than that for Fe(terpy) 2þ 2 , which is also consistent with formation of this intermediate ternary complex. Burgess et al [23] reported the dissociation and base hydrolysis of tris (3-(2-pyridyl)-5,6-bis(2-furyl)-1,2,4triazine)iron(II) in MeOH-water solvent mixtures with a view to compare substitution rates for tris(3-(2-pyridyl)-5,6-bis(5-furyl sulfonic acid)-1,2,4-triazine)iron(II) with those for its non-sulfonated parent. Here also, the base hydrolysis was found to be a fairly rapid two-stage process with the first step requiring stopped-flow techniques, while the second step was amenable to monitoring by conventional spectrophotometry.…”

Spectrophotometric study of Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Hg(II) complexes with isatin-β-thiosemicarbazone

“…The stability constants of the complexes predominant in solution were calculated according to a computerized iterative method of successive approximations. 11,12 The obtained composition and logE n values with standard errors are presented in Table I. The values of the stability constants are relative, since the dissociation of the ligand was not taken into consideration.…”