Mechanistic Investigation on the Water Substitution in the η5-Organometallic Complexes Cp*Ir(H2O)32+and Cp*Rh(H2O)32+

Cayemittes, Sonia; Poth, Tilo; Fernández, María José Frutos; Lye, Peter G.; Becker, Matthias; Elias, Horst; Merbach, André E.

doi:10.1021/ic990364w

Cited by 32 publications

(40 citation statements)

References 22 publications

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“…[7] Ϫ [b] Taken from ref. [9] At pH Յ 5, the formation of monohydroxo species Cp* Ir(AϪB)(OH) ϩ/0 can be neglected. (4) …”

Section: Properties Of the Monoaqua Species Cp*ir(a؊b)(h 2 O) 2؉/؉mentioning

confidence: 99%

“…Ir (1)ϪN (20) 2.127 (8) N (20)ϪIr (1)ϪN (13) 79.0(3) Ir (1)ϪN (13) 2.130 (8) N (20)ϪIr (1)ϪO (2) 80.9(3) Ir (1)ϪO (2) 2.180 (7) N (13)ϪIr (1)ϪO (2) 83.6(3) Ir (1)ϪC (3) 2.180 (9) X1aϪIr (1)ϪO (2) [a] 128.7(3) Ir (1)ϪC (4) 2.143 (12) X1aϪIr (1)ϪN (13) [a] 132.0(4) Ir (1)ϪC (5) 2.113 (9) X1aϪIr (1)ϪN (20) [a] 133.0(4) Ir (1)ϪC (6) 2.178 (9) C (19)ϪN (20)ϪIr (1) 110.2(5) Ir(1)ϪC (7) 2.170(9) C (19)ϪC (14)ϪN (13) 108.9(6) Ir(1)ϪX1a [a] 1.777(2) C (14)ϪN (13)ϪIr (1) 111.9(5) N(13)ϪC(14) 1.502 (9) C (14)ϪC (19)ϪN (20) 108.1(6) C (19)ϪN (20) 1.510 (9) C (4)ϪIr …”

Section: Structures Of the Complexes 2b And 3bmentioning

confidence: 99%

“…Ϫ [e] First substitution step; data taken from ref. [9] ∆A ϭ A ϱ K[py] tot /(1 ϩ K[py] tot ) (8) The values of k L , k ϪL , and K obtained are summarized in Table 6.…”

Section: Water Substitution In Complexes Cp*ir(a؊b)(h 2 O) 2؉/؉ By Pymentioning

confidence: 99%

“…[31] Within the limits of error, this value is in agreement with k ϪL ϭ (0.8 Ϯ 0.3) ϫ 10 Ϫ3 s Ϫ1 as determined from the kinetics of the complex formation reaction (see Table 6). This means that the pH-jump from pH ϭ 2 to higher proton concentrations causes aquation of the cation Cp*Ir(R,R-dach)(py-nia) 2ϩ according to Equation (9). Due to pyridine protonation at the high proton concentrations employed, the contribution of the rate term k L [py] in Equation (7) becomes negligibly small.…”

Section: Water Substitution In Complexes Cp*ir(a؊b)(h 2 O) 2؉/؉ By Pymentioning

confidence: 99%

“…Ϫ [f] First substitution step; data, as taken from ref. [9] , refer to the substitution of 1 water molecule in 1. [a] For abbreviations, see ref.…”

Section: Cation Phmentioning

confidence: 99%

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Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations CpIr(A−B)(H2O)2+/+ in Aqueous Solution (Cp = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Poth

Paulus

Elias

et al. 2001

Eur. J. Inorg. Chem.

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The perchlorate complexes of a series of half‐sandwich monoaqua cations Cp*Ir(A−B)(H2O)2+/+ with A−B = prol (D/L‐proline anion), picac (picolinic acid anion), R,R‐dach [(−)‐(1R,2R)‐1,2‐diaminocyclohexane], R,R‐dpen [(+)‐(1R,2R)‐1,2‐diphenylethylenediamine], phen (o‐phenanthroline), and bpy (2,2′‐bipyridine) (Cp* = η5‐pentamethylcyclopentadienyl anion) have been prepared and characterized. An X‐ray structure analysis of Cp*Ir(R,R‐dach)(H2O)(ClO4)2·H2O has revealed that the cation Cp*Ir(R,R‐dach)(H2O)2+ has a distorted pseudo‐octahedral coordination geometry. In the case of A−B = prol, crystallization from water led to the trinuclear complex [Cp*Ir(D‐prol)]3(ClO4)3, which has also been characterized by X‐ray structure analysis. The experimental data suggest that in aqueous solution the trinuclear proline complex dissociates to form the cation Cp*Ir(D‐prol)(H2O)+. The proton dissociation constants of the coordinated water in Cp*Ir(A−B)(H2O)2+/+ have been determined as pKa = 7.5 (A−B = bpy) and pKa = 7.1 (A−B = R,R‐dach and picac). Substitution of the water in Cp*Ir(A−B)(H2O)2+/+ by the monodentate ligands L = py (pyridine), DMS (dimethyl sulfide), TU (thiourea), and monodentate anions according to the Equation Cp*Ir(A−B)(H2O)2+/+ + L → Cp*Ir(A−B)L2+/+ + H2O has been studied by multi‐wavelength stopped‐flow spectrophotometry in aqueous solution at I = 0.2 M. This kinetic investigation, carried out at different concentrations, temperatures, and pressures, showed that the process obeys second‐order kinetics, where rate = kL[Cp*Ir(A−B)H2O2+/+][L]. The magnitude of the second‐order rate constant kL depends on the nature of both A−B and L. The data for kL have been found to range from 6.4 × 104 M−1s−1 (A−B = D‐prol; L = TU) to 10.5 M−1s−1 (A−B = bpy; L = py) at 298 K. The activation parameters for water substitution at Cp*Ir(A−B)(H2O)2+/+ (A−B = bpy, R,R‐dach, and picac) by L = TU have been evaluated. The activation volumes of ΔV≠ = +2.3, +7.4, and +7.3 cm3 mol−1, respectively, are supportive of an Id mechanism. The results regarding the kinetic lability of the coordinated water in the monoaqua cations Cp*Ir(A−B)(H2O)2+/+ are compared to those obtained for the triaqua cation Cp*Ir(H2O)32+.

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“…[7] Ϫ [b] Taken from ref. [9] At pH Յ 5, the formation of monohydroxo species Cp* Ir(AϪB)(OH) ϩ/0 can be neglected. (4) …”

Section: Properties Of the Monoaqua Species Cp*ir(a؊b)(h 2 O) 2؉/؉mentioning

confidence: 99%

Section: Structures Of the Complexes 2b And 3bmentioning

confidence: 99%

“…Ϫ [e] First substitution step; data taken from ref. [9] ∆A ϭ A ϱ K[py] tot /(1 ϩ K[py] tot ) (8) The values of k L , k ϪL , and K obtained are summarized in Table 6.…”

Section: Water Substitution In Complexes Cp*ir(a؊b)(h 2 O) 2؉/؉ By Pymentioning

confidence: 99%

Section: Water Substitution In Complexes Cp*ir(a؊b)(h 2 O) 2؉/؉ By Pymentioning

confidence: 99%

“…Ϫ [f] First substitution step; data, as taken from ref. [9] , refer to the substitution of 1 water molecule in 1. [a] For abbreviations, see ref.…”

Section: Cation Phmentioning

confidence: 99%

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Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations CpIr(A−B)(H2O)2+/+ in Aqueous Solution (Cp = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Poth

Paulus

Elias

et al. 2001

Eur. J. Inorg. Chem.

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Water Activation: Catalytic Hydrolysis

Berreau

2006

Activation of Small Molecules

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Lisa M. Berreau 8.1 8.1.2 Catalytic Hydrolysis Significant effort has been put forth toward the development of synthetic metal complexes capable of hydrolytically cleaving biologically relevant substrates (amides, carboxylic and phosphate esters, DNA, RNA, etc.), both selectively and 287 Activation of Small Molecules. Edited by William B. Tolman 8 Water Activation: Catalytic Hydrolysis with high catalytic efficiency [16][17][18][19][20]. In this regard, several recent studies have focused on evaluating how the incorporation of biomimetic secondary hydrogen-bonding (H-bonding) interactions in synthetic metal complexes influences phosphate ester coordination, activation and hydrolysis. The emergence of this line of research parallels efforts toward evaluating how the presence of H-bond donors influences a variety of small-molecule reactions, including dioxygen coordination and activation (Chapter 6) [21].In this chapter, I summarize newly discovered fundamental chemistry of synthetic complexes that provides insight into how: (i) primary and secondary coordination sphere components influence the acidity and structural features of a metalbound water molecule, and (ii) how secondary H-bonding interactions influence the metal coordination properties and hydrolytic reactivity of phosphate esters. Water Activation: Coordination Sphere Effects on M-OH 2 Acidity and Structure Primary Coordination Environment8 Water Activation: Catalytic Hydrolysis

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β‐Ketoiminato Iridium(III) Organometallic Complexes: Selective Cytotoxicity towards Colorectal Cancer Cells HCT116 p53‐/‐

Lord

Zegke

Henderson

et al. 2018

Chemistry A European J

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This report presents an ew libraryo fo rganometallic iridium(III) compounds of the type [Cp*IrCl(L)] (Cp* = pentamethylcyclopentadienyl and L = af unctionalized bketoiminato ligand) showingm oderatet oh igh cytotoxicity against ar ange of cancerc ell lines. All compounds show increased activity towards colorectal cancer, with preferential activity observed against the immortalized p53-null colorectalc ell line, HCT116 p53-/-, with sensitivity factors (SF) up to 26.7. Additionally,t he compounds have excellent selectivity for cancerous cells when tested againstn ormal cell types, with selectivity ratios (SR) up to 35.6, contrary to that of cisplatin,whichisneither selective nor specific forc ancerous cells (SF = 0.43 and SR = 0.7-2.3). This work provides ap reliminary understanding of the cytotoxicityo fi ridium compoundsi nt he absence of p53 and hasp otentiala pplications in treatment of cancers for which the p53 gene is absent or mutant.

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Mechanistic Investigation on the Water Substitution in the η⁵-Organometallic Complexes CpIr(H₂O)₃²⁺and CpRh(H₂O)₃²⁺

Cited by 32 publications

References 22 publications

Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations CpIr(A−B)(H2O)2+/+ in Aqueous Solution (Cp = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations CpIr(A−B)(H2O)2+/+ in Aqueous Solution (Cp = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Water Activation: Catalytic Hydrolysis

β‐Ketoiminato Iridium(III) Organometallic Complexes: Selective Cytotoxicity towards Colorectal Cancer Cells HCT116 p53‐/‐

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Mechanistic Investigation on the Water Substitution in the η5-Organometallic Complexes Cp*Ir(H2O)32+and Cp*Rh(H2O)32+

Cited by 32 publications

References 22 publications

Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations Cp*Ir(A−B)(H2O)2+/+ in Aqueous Solution (Cp* = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations Cp*Ir(A−B)(H2O)2+/+ in Aqueous Solution (Cp* = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Water Activation: Catalytic Hydrolysis

β‐Ketoiminato Iridium(III) Organometallic Complexes: Selective Cytotoxicity towards Colorectal Cancer Cells HCT116 p53‐/‐

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Mechanistic Investigation on the Water Substitution in the η⁵-Organometallic Complexes CpIr(H₂O)₃²⁺and CpRh(H₂O)₃²⁺

Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations CpIr(A−B)(H2O)2+/+ in Aqueous Solution (Cp = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)

Kinetics and Mechanism of Water Substitution at Half-Sandwich Iridium(III) Aqua Cations CpIr(A−B)(H2O)2+/+ in Aqueous Solution (Cp = η5-Pentamethylcyclopentadienyl Anion; A−B = Bidentate N,N or N,O Ligand)