Kinetic and mechanistic study on the reactions of [Pt(bpma)(H2O)]2+and [Pd(bpma)(H2O)]2+with some nucleophiles. Crystal structure of [Pd(bpma)(py)](ClO4)2

Jaganyi, Deogratius; Tiba, Felicia; Munro, Orde Q.; Petrović, Biljana; Bugarčić, Živadin D.

doi:10.1039/b602950g

Cited by 61 publications

(27 citation statements)

References 34 publications

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“…Under this condition, the stability constants (K eq ) for the complexes formed with INO and 5Ј-GMP were calculated using Equation (7) and (8), respectively. log K eq = logβ 111 -logβ 011 (7) log K eq = logβ 112 -logβ 012 (8) The log K eq values were found to be 4.33 and 4.21 for INO and 5Ј-GMP, respectively, and are in reasonable agreement with those estimated from the kinetic data at pH 4.75 (Table 3). Table 2.…”

Section: Comparison Of Thermodynamic and Kinetic Datasupporting

confidence: 75%

Equilibrium and Kinetic Studies of the Reactions between Aqua[1‐(2‐aminoethyl)piperazine]palladium(II) and Biologically Relevant Nucleophiles

et al. 2009

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The kinetics and mechanism of the complex-formation reactions of [Pd(AEP)(H 2 O)] 2+ , where AEP stands for 1-(2-aminoethyl)piperazine, with biologically relevant ligands were studied as a function of selected nucleophiles and pH. The reactivity of the ligands follows the sequence L-methionine Ͼ guanosine-5Ј-monophosphate Ͼ glycine Ͼ inosine ϾϾ glutathione. The substitution reactions with glutathione showed two reaction steps in which the first step involves coordination through nitrogen and depends on the nucleophile concentration, whereas the second step involves intra-

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Section: Comparison Of Thermodynamic and Kinetic Datasupporting

confidence: 75%

Equilibrium and Kinetic Studies of the Reactions between Aqua[1‐(2‐aminoethyl)piperazine]palladium(II) and Biologically Relevant Nucleophiles

et al. 2009

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“…2+ by DMTU and TU, with DMTU reacting faster than TU [64]. In this instance, the authors attributed the effect to the greater inductive effect for DMTU over TU, which overcame steric hindrance, and indeed the case may be that the inductive effect of TMTU is greater than that of DMTU and that via some form of "trans-effect" through the azine linker, leads to a moderate increase in the rate of substitution of the second aqua moiety.…”

Section: Ligand Substitutionsmentioning

confidence: 87%

Influence of the bridging azine ligand on the rate of ligand substitution in a series of dinuclear platinum(II) complexes

Reddy

Jaganyi

2011

Int J of Chemical Kinetics

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A series of azine-bridged dinuclear platinum(II) complexes of the type [{trans-Pt(NH 3 ) 2 (OH 2 )} 2 (μ-azn)](ClO 4 ) 4 (where azn = pyrazine (pzn, Pt1), 2,3-dimethylpyrazine (2,3-pzn, Pt2), and 2,5-dimethylpyrazine (2,5-pzn, Pt3)) were synthesized to investigate the influence of the bridging azine ligand on the reactivity of the platinum(II) centers. The pK a values of the complexes were determined via acid-base titration, and the rate of substitution of the aqua moiety by a series of neutral nucleophiles, viz. thiourea (TU), 1,3-dimethyl-2-thiourea (DMTU), and 1,1,3,3-tetramethyl-2-thiourea (TMTU), was determined under pseudo-first-order conditions as a function of concentration and temperature using standard spectrophotometric techniques. The introduction of the methyl groups to the bridging azine linker in Pt2 and Pt3 leads to a moderate increase in the pK a values obtained for the first and second deprotonation steps, respectively, as a result of the increased σ-donor capacity of the bridging azine ligand trans to the aqua moiety. A comparison of the rate constants, k 1 and k 2 , at 298 K, obtained for the substitution of the aqua moieties from Pt1, Pt2, and Pt3 by TU, shows that the introduction of the σ-donating methyl groups on the bridging azine ligand in Pt2 and Pt3 results in a corresponding decrease in the reactivity, by ca. five times for the first substitution step and ca. 10 times for the second substitution step. Density functional theory calculations at the B3LYP/LACVP** level of theory for the complexes demonstrate that the introduction of electron-donating methyl groups results in (i) increased steric hindrance over the metal centers and (ii) decreased the positive charge on the metal center and increases energy separation of the frontier molecular orbitals (E HOMO -E LUMO ) of the ground-state platinum(II) complexes, leading to a less-reactive metal center. C

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“…-) 2 , [19] and 2.038(4) Å in [(2,2Ј:6Ј,2ЈЈ-terpyridine)Pd(pyridine)](ClO 4 -) 2 . [20] It is noteworthy that a weakly-bound pyridine moiety is a strategic Scheme 2. hallmark of a PEPPSI-themed precatalyst.…”

Section: 037(3) å In [Bis(bis(2-pyridylmethyl)amine-nnјnјј)]pd(pyrmentioning

confidence: 99%

Fluoride‐Free Hiyama and Copper‐ and Amine‐Free Sonogashira Coupling in Air in a Mixed Aqueous Medium by a Series of PEPPSI‐Themed Precatalysts

2009

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A new series of robust, user‐friendly, and highly active PEPPSI‐themed (pyridine‐enhanced precatalyst preparation, stabilization and initiation) (NHC)PdX2(pyridine)‐type (X = Cl, Br) precatalysts of C4–C5 saturated imidazole‐ (1–4) and triazole‐based (5 and 6) N‐heterocyclic carbenes for the Hiyama and Sonogashira couplings under amenable conditions are reported. Specifically 1–6 efficiently catalyze the fluoride‐free Hiyama coupling of aryl halides with PhSi(OMe)3 and CH2=CHSi(OMe)3 in air in the presence of NaOH as a base in a mixed aqueous medium (dioxane/H2O, 2:1 v/v). Along the same lines, these 1–6 precatalysts also promote the Cu‐free and amine‐free Sonogashira coupling of aryl bromides and iodides with phenylacetylene in air and in a mixed aqueous medium (DMF/H2O, 3/1 v/v). The complexes 1–6 were synthesized by the direct reaction of the respective imidazolinium and triazolium halide salts with PdCl2 in pyridine in the presence of K2CO3 as a base. DFT studies on the catalytically relevant palladium(0) (NHC)Pd(pyridine) precursors 1a–6a reveal significant donation from the N‐heterocyclic carbene lone pair onto the unfilled σ* orbital of the trans Pd–pyridine bond. This weakens the Pd‐bound “throwaway” pyridine ligand, and its dissociation marks the initiation of the catalytic cycle.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Kinetic and mechanistic study on the reactions of [Pt(bpma)(H₂O)]²⁺and [Pd(bpma)(H₂O)]²⁺with some nucleophiles. Crystal structure of [Pd(bpma)(py)](ClO₄)₂

Cited by 61 publications

References 34 publications

Equilibrium and Kinetic Studies of the Reactions between Aqua[1‐(2‐aminoethyl)piperazine]palladium(II) and Biologically Relevant Nucleophiles

Equilibrium and Kinetic Studies of the Reactions between Aqua[1‐(2‐aminoethyl)piperazine]palladium(II) and Biologically Relevant Nucleophiles

Influence of the bridging azine ligand on the rate of ligand substitution in a series of dinuclear platinum(II) complexes

Fluoride‐Free Hiyama and Copper‐ and Amine‐Free Sonogashira Coupling in Air in a Mixed Aqueous Medium by a Series of PEPPSI‐Themed Precatalysts

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