Osmium(II) and ruthenium(II) arene maltolato complexes: Rapid hydrolysis and nucleobase binding

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Osmium(II) and ruthenium(II) arene maltolato complexes: Rapid hydrolysis and nucleobase binding. / Peacock, Anna; Melchart, M; Deeth, RJ; Habtemariam, A; Parsons, S; Sadler, PJ.

In: Chemistry: A European Journal, Vol. 13, No. 9, 01.01.2007, p. 2601-2613.

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Peacock, Anna ; Melchart, M ; Deeth, RJ ; Habtemariam, A ; Parsons, S ; Sadler, PJ. / Osmium(II) and ruthenium(II) arene maltolato complexes: Rapid hydrolysis and nucleobase binding. In: Chemistry: A European Journal. 2007 ; Vol. 13, No. 9. pp. 2601-2613.

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@article{3b2e673d213843839a076456550c8546,
title = "Osmium(II) and ruthenium(II) arene maltolato complexes: Rapid hydrolysis and nucleobase binding",
abstract = "Density functional calculations show that aquation of [Os(eta(6)-arene)(XY)Cl](n+) complexes is more facile for complexes in which XY=an anionic O,O-chelated ligand compared to a neutral N,N-chelated ligand, and the mechanism more dissociative in character. The O,O-chelated XY=maltolato (mal) [M(eta(6)-p-cym)(mal)Cl] complexes, in which p-cvm=p-cymene, M=Os-II (1) and Run (2). were synthesised and the X-ray crystal structures of I and 2-2H(2)O determined. Their hydrolysis rates were rapid (too fast to follow by NMR spectroscopy). The aqua adduct of the Os-II complex 1 was 1.6 pK(a) units more acidic than that of the Ru-II complex 2. Dynamic NMR studies suggested that O,O-chelate ring opening occurs on a millisecond timescale in coordinating proton-donor solvents, and loss of chelated mal in aqueous solution led to the formation of the hydroxo-bridged dimers [(eta(6)-p-cyrn)M(mu-OH)(3)M(eta(6)-p-cym)](+). ne proportion of this dimer in solutions of the Os-II complex 1 increased with dilution and it predominated at micromolar concentrations, even in the presence of 0.1 M NaCl (conditions close to those used for cytotoxicity testing). Although 9-ethylguanine (9-EtG) binds rapidly to Os-II in 1 and more strongly (log K=4.4) than to Ru-II in 2 (log K=3.9), the Os-II adduct [Os(eta(6)-p-cym)(mal)-(9EtG)](+) was unstable with respect to formation of the hydroxo-bridged dimer at micromolar concentrations. Such insights into the aqueous solution chemistry of metal-arene complexes under biologically relevant conditions will aid the rational design of organometallic anticancer agents.",
keywords = "density functional calculations, osmium, ruthenium, bioinorganic chemistry, O ligands",
author = "Anna Peacock and M Melchart and RJ Deeth and A Habtemariam and S Parsons and PJ Sadler",
year = "2007",
month = jan
day = "1",
doi = "10.1002/chem.200601152",
language = "English",
volume = "13",
pages = "2601--2613",
journal = "Chemistry: A European Journal",
issn = "0947-6539",
publisher = "Wiley-VCH Verlag",
number = "9",

}

RIS

TY - JOUR

T1 - Osmium(II) and ruthenium(II) arene maltolato complexes: Rapid hydrolysis and nucleobase binding

AU - Peacock, Anna

AU - Melchart, M

AU - Deeth, RJ

AU - Habtemariam, A

AU - Parsons, S

AU - Sadler, PJ

PY - 2007/1/1

Y1 - 2007/1/1

N2 - Density functional calculations show that aquation of [Os(eta(6)-arene)(XY)Cl](n+) complexes is more facile for complexes in which XY=an anionic O,O-chelated ligand compared to a neutral N,N-chelated ligand, and the mechanism more dissociative in character. The O,O-chelated XY=maltolato (mal) [M(eta(6)-p-cym)(mal)Cl] complexes, in which p-cvm=p-cymene, M=Os-II (1) and Run (2). were synthesised and the X-ray crystal structures of I and 2-2H(2)O determined. Their hydrolysis rates were rapid (too fast to follow by NMR spectroscopy). The aqua adduct of the Os-II complex 1 was 1.6 pK(a) units more acidic than that of the Ru-II complex 2. Dynamic NMR studies suggested that O,O-chelate ring opening occurs on a millisecond timescale in coordinating proton-donor solvents, and loss of chelated mal in aqueous solution led to the formation of the hydroxo-bridged dimers [(eta(6)-p-cyrn)M(mu-OH)(3)M(eta(6)-p-cym)](+). ne proportion of this dimer in solutions of the Os-II complex 1 increased with dilution and it predominated at micromolar concentrations, even in the presence of 0.1 M NaCl (conditions close to those used for cytotoxicity testing). Although 9-ethylguanine (9-EtG) binds rapidly to Os-II in 1 and more strongly (log K=4.4) than to Ru-II in 2 (log K=3.9), the Os-II adduct [Os(eta(6)-p-cym)(mal)-(9EtG)](+) was unstable with respect to formation of the hydroxo-bridged dimer at micromolar concentrations. Such insights into the aqueous solution chemistry of metal-arene complexes under biologically relevant conditions will aid the rational design of organometallic anticancer agents.

AB - Density functional calculations show that aquation of [Os(eta(6)-arene)(XY)Cl](n+) complexes is more facile for complexes in which XY=an anionic O,O-chelated ligand compared to a neutral N,N-chelated ligand, and the mechanism more dissociative in character. The O,O-chelated XY=maltolato (mal) [M(eta(6)-p-cym)(mal)Cl] complexes, in which p-cvm=p-cymene, M=Os-II (1) and Run (2). were synthesised and the X-ray crystal structures of I and 2-2H(2)O determined. Their hydrolysis rates were rapid (too fast to follow by NMR spectroscopy). The aqua adduct of the Os-II complex 1 was 1.6 pK(a) units more acidic than that of the Ru-II complex 2. Dynamic NMR studies suggested that O,O-chelate ring opening occurs on a millisecond timescale in coordinating proton-donor solvents, and loss of chelated mal in aqueous solution led to the formation of the hydroxo-bridged dimers [(eta(6)-p-cyrn)M(mu-OH)(3)M(eta(6)-p-cym)](+). ne proportion of this dimer in solutions of the Os-II complex 1 increased with dilution and it predominated at micromolar concentrations, even in the presence of 0.1 M NaCl (conditions close to those used for cytotoxicity testing). Although 9-ethylguanine (9-EtG) binds rapidly to Os-II in 1 and more strongly (log K=4.4) than to Ru-II in 2 (log K=3.9), the Os-II adduct [Os(eta(6)-p-cym)(mal)-(9EtG)](+) was unstable with respect to formation of the hydroxo-bridged dimer at micromolar concentrations. Such insights into the aqueous solution chemistry of metal-arene complexes under biologically relevant conditions will aid the rational design of organometallic anticancer agents.

KW - density functional calculations

KW - osmium

KW - ruthenium

KW - bioinorganic chemistry

KW - O ligands

U2 - 10.1002/chem.200601152

DO - 10.1002/chem.200601152

M3 - Article

C2 - 17200926

VL - 13

SP - 2601

EP - 2613

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

SN - 0947-6539

IS - 9

ER -