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

Rao, Garimella Visweswara; Bellam, Rajesh; Anipindi, Nageswra Rao

doi:10.1007/s11243-011-9574-z

Cited by 6 publications

(5 citation statements)

References 19 publications

(20 reference statements)

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“…The comparable magnitudes of DG # 35 C values for the reactions of the three different Pt(II) complexes with Sdonor nucleophiles, suggest that all these reactions essentially follow the same mechanism which is associative. 15 The relatively smaller enthalpy of activation (DH # ) values suggests that it is energetically favorable to form a bond in a bimolecular transition state. 16 It is also well-known that relatively large negative entropy of activation (DS # ) values signify the bimolecular nature of a transition state.…”

Section: +mentioning

confidence: 99%

Seven membered chelate Pt(ii) complexes with 2,3-di(2-pyridyl)quinoxaline ligands: studies of substitution kinetics by sulfur donor nucleophiles, interactions with CT-DNA, BSA and in vitro cytotoxicity activities

et al. 2019

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confidence: 99%

Seven membered chelate Pt(ii) complexes with 2,3-di(2-pyridyl)quinoxaline ligands: studies of substitution kinetics by sulfur donor nucleophiles, interactions with CT-DNA, BSA and in vitro cytotoxicity activities

et al. 2019

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“…The intermediate complexes, Fe(L n )(L′ 3– n ) x− (where L = PDTS/PPDTS, L′ = phen, bpy, or terpy), were isolated using Dowex 50W‐X8 cation‐exchange and Dowex 1×8 anion‐exchange resin columns. Earlier it had been found that the substitution of bis(2,4,6‐tripyridyl 1,3,5‐ triazine)iron(II),

{Fe false(TPTZ false)}_{2}^{2 +}

, by terpy took place in two steps. The first step involves replacement of a TPTZ molecule by terpy forming an intermediate, Fe(TPTZ)(terpy) 2+ , which further reacts with excess terpy to give the final product

{Fe false(terpy false)}_{2}^{2 +}

.…”

Section: Methodsmentioning

confidence: 99%

Substitution Kinetics of [Fe(PDT/PPDT)_n(phen)_m]²⁺(n≠m;n,m= 1,2) with 2,2′-Bipyridine, 1,10-Phenanthroline, and 2,2′,6,2″-Terpyridine

Bellam

Jaganyi

2017

Int. J. Chem. Kinet.

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The triazines 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT), 3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PPDT), and 1,10-phenanthroline (phen) were coordinated to the Fe 2+ ion to form Fe(PDT) 2 (phen) 2+ (1), Fe(PPDT) 2 (phen) 2+ (2), Fe(PDT)(phen) 2+ 2 , (3) and Fe(PPDT)(phen) 2+ 2 (4). The complexes were synthesized and characterized by mass spectroscopy and elemental analysis. The rate of substitution of these complexes by 2,2 -bipyridine (bpy), 1,10-phenanthroline (phen), and 2,2 ,6,2 -terpyridine (terpy) was studied in a sodium acetate-acetic acid buffers over the range 3.6-5.6 at 25, 35, and 45°C under pseudo-first-order conditions. The reactions are first order with respect to the concentration of the complexes. The reaction rates increase with increasing [bpy/phen/terpy] and pH, whereas ionic strength has no influence on the rate of reaction. Plots of k obs versus [bpy/phen/terpy] and 1/[H + ] are linear with positive slopes and significant y-intercepts. This indicates that the reactions proceed by both dissociative as well as associative pathways for which the associative pathway predominates the substitution kinetics. Observed temperature-depended rate constants at the three temperatures at which substitution reactions were studied together with the protonation constants of the substituting ligands (phen, bpy, terpy) were used to evaluate the specific rate constants (k 1 and k 2 ) and thermodynamic parameters (E a , H # , S # , and G # ). The reactivity order of the four complexes depends on the phenyl groups present on the triazine (PDT/PPDT)Correspondence to: R. Bellam; e-mail: rajeshchowdarybellam@ gmail.com.Supporting Information is available in the online issue at www.wileyonlinelibrary.com.C 2017 Wiley Periodicals, Inc. SUBSTITUTION KINETICS OF [Femolecule. The π -electrons on phenyl rings stabilizes the charge on the metal center by inductive donation of electrons toward the metal center resulting in a decrease in reactivity of the complex, and the order is 1 < 2 < 3 < 4. The rate of substitution is also influenced by the basicity of the incoming ligand (bpy/phen/terpy), and it decreased in the order: phen > terpy > bpy. Higher rate constants, low E a values , and more negative entropy of activation (− S # ) values were observed for the associative path, revealing that substitution reactions at the octahedral iron(II) complexes by bpy, phen, and terpy occur predominantly by the associative mechanism. Density functional theory calculations support the interpretations.

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“…The incoming ligand is partially coordinated to the metal center and the leaving ligand is partially dissociated. 18,19,[28][29][30] The second step of reaction is the first-order and independent on [teazma] macrocycle with rate constant k bctn (2). The rate of the ligand exchange reaction is controlled by this step (rate-determining step).…”

Section: Proposed Mechanism Of Cu(bctn) 2+ /Teazma Systemmentioning

confidence: 99%

Kinetics and Mechanism of the Ligand Exchange Reaction Between Tetraaza Macrocycle Ligand and Cu(II) Tetradentate Amine-Amide Complexes

Vafazadeh

Zare-Sadrabadi

2015

ACSi

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The kinetics of the ligand exchange reaction of tetraaza macrocycle, teazma (teazma is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene dihydrogen perchlorate) with Cu(bcen) 2+ and Cu(bctn) 2+ , where bcen and bctn are N,N'-bis(β-carbamoylethyl) ethylendiamine) and N,N'-bis(β-carbamoylethyl) propylendiamine), respectively, have been studied by visible spectrophotometry in dimethylformamide, DMF, solvent at 25 ± 0.2 °C. In the system of Cu(bctn) 2+ /teazma, the ligand exchange reaction proceeds in a two-step-consecutive manner, with two rate constants k bctn obsd (1) and k bctn obsd (2). The first reaction step was dependent on the concentration of teazma macrocycle, while the second reaction step was independent. However, it is found that the ligand exchange reaction in Cu(bcen) 2+ /teazma proceeds in an one-step with the rate constant k bcen obsd. The rate constant is dependent on [teazma] macrocycle. The ligand exchange reaction in the system of Cu(bcen) 2+ /teazma is not complete and after some progress, the reaction reaches equilibrium. On the basis of results, a reaction mechanism is proposed and discussed for the ligand exchange rate.

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

Cited by 6 publications

References 19 publications

Seven membered chelate Pt(ii) complexes with 2,3-di(2-pyridyl)quinoxaline ligands: studies of substitution kinetics by sulfur donor nucleophiles, interactions with CT-DNA, BSA and in vitro cytotoxicity activities

Seven membered chelate Pt(ii) complexes with 2,3-di(2-pyridyl)quinoxaline ligands: studies of substitution kinetics by sulfur donor nucleophiles, interactions with CT-DNA, BSA and in vitro cytotoxicity activities

Substitution Kinetics of [Fe(PDT/PPDT)_n(phen)_m]²⁺(n≠m;n,m= 1,2) with 2,2′-Bipyridine, 1,10-Phenanthroline, and 2,2′,6,2″-Terpyridine

Kinetics and Mechanism of the Ligand Exchange Reaction Between Tetraaza Macrocycle Ligand and Cu(II) Tetradentate Amine-Amide Complexes

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

Cited by 6 publications

References 19 publications

Seven membered chelate Pt(ii) complexes with 2,3-di(2-pyridyl)quinoxaline ligands: studies of substitution kinetics by sulfur donor nucleophiles, interactions with CT-DNA, BSA and in vitro cytotoxicity activities

Seven membered chelate Pt(ii) complexes with 2,3-di(2-pyridyl)quinoxaline ligands: studies of substitution kinetics by sulfur donor nucleophiles, interactions with CT-DNA, BSA and in vitro cytotoxicity activities

Substitution Kinetics of [Fe(PDT/PPDT)n(phen)m]2+(n≠m;n,m= 1,2) with 2,2′-Bipyridine, 1,10-Phenanthroline, and 2,2′,6,2″-Terpyridine

Kinetics and Mechanism of the Ligand Exchange Reaction Between Tetraaza Macrocycle Ligand and Cu(II) Tetradentate Amine-Amide Complexes

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Substitution Kinetics of [Fe(PDT/PPDT)_n(phen)_m]²⁺(n≠m;n,m= 1,2) with 2,2′-Bipyridine, 1,10-Phenanthroline, and 2,2′,6,2″-Terpyridine