Gold(III) and palladium(II) complexes of glycylglycyl-L-histidine

Crystal structures of [AuIII(Gly-Gly-L-His-H-2)]Cl·H2O and [PdII(Gly-Gly-L-His-H-2)]·1.5H2O and HisεNH deprotonation

Sabine L. Best, Tapan K. Chattopadhyay, Milos I. Djuran, Rex A. Palmer, Peter J. Sadler, I. Sóvágó, K. Várnagy

Research output: Contribution to journalArticle

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Abstract

Proton NMR studies show that [AuCl4]- reacts slowly with glycylglycyl-L-histidine (Gly-Gly-L-His) (t1/2 = 9.3 h at 310 K and pH* 2) in D2O at pH* (meter reading) values as low as 1.5 to form the stable complex [AuIII(Gly-Gly-L-His-H-2)]C1·O 1 via one intermediate. Complex 1 is shown by X-ray crystallography to be square-planar with gold bound to the terminal NH2 [Au-N 2.049(10) Å], two deprotonated amide nitrogens [Au-N- 1.941(9), 2.006(10) Å] and HisδN [Au-N 2.038(9) Å] giving one six-membered and two five-membered chelate rings. At pH* 7 the reaction of [AuCl4]- with Gly-Gly-L-His follows a different course, apparently involving the formation of AuIII cross-linked polymers. The anion [PdCl4]2- reacts rapidly with Gly-Gly-L-His also at pH* 2, and forms a similar square-planar complex [PdII(Gly-Gly-L-His-H-2)]·1.5H2O 2 involving the terminal NH2 [Pd-N 2.058(7) Å], two deprotonated amide nitrogens [Pd-N- 1.943(7), 1.983(6) Å] and HisδN [Pd-N 2.016(6) Å]. By potentiometry, pKa values of 2.58 (CO2H), 8.63 (HisεNH, 'pyrrole nitrogen') and 11.50 (co-ordinated NH2) for 1 and 11.30 (HisεNH) for 2 were determined and confirmed by 1H NMR spectroscopy.

Original languageEnglish
Pages (from-to)2587-2596
Number of pages10
JournalJournal of the Chemical Society, Dalton Transactions
Issue number15
Publication statusPublished - Aug 7 1997

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diglycyl-histidine
Deprotonation
Palladium
Gold
Nitrogen
Crystal structure
Amides
pH meters
Pyrroles
X ray crystallography
Nuclear magnetic resonance spectroscopy
Anions
Protons
Polymers
Nuclear magnetic resonance

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Gold(III) and palladium(II) complexes of glycylglycyl-L-histidine : Crystal structures of [AuIII(Gly-Gly-L-His-H-2)]Cl·H2O and [PdII(Gly-Gly-L-His-H-2)]·1.5H2O and HisεNH deprotonation. / Best, Sabine L.; Chattopadhyay, Tapan K.; Djuran, Milos I.; Palmer, Rex A.; Sadler, Peter J.; Sóvágó, I.; Várnagy, K.

In: Journal of the Chemical Society, Dalton Transactions, No. 15, 07.08.1997, p. 2587-2596.

Research output: Contribution to journalArticle

@article{83a2461d9e5d4b6bb947d58b500ac04c,
title = "Gold(III) and palladium(II) complexes of glycylglycyl-L-histidine: Crystal structures of [AuIII(Gly-Gly-L-His-H-2)]Cl·H2O and [PdII(Gly-Gly-L-His-H-2)]·1.5H2O and HisεNH deprotonation",
abstract = "Proton NMR studies show that [AuCl4]- reacts slowly with glycylglycyl-L-histidine (Gly-Gly-L-His) (t1/2 = 9.3 h at 310 K and pH* 2) in D2O at pH* (meter reading) values as low as 1.5 to form the stable complex [AuIII(Gly-Gly-L-His-H-2)]C1·O 1 via one intermediate. Complex 1 is shown by X-ray crystallography to be square-planar with gold bound to the terminal NH2 [Au-N 2.049(10) {\AA}], two deprotonated amide nitrogens [Au-N- 1.941(9), 2.006(10) {\AA}] and HisδN [Au-N 2.038(9) {\AA}] giving one six-membered and two five-membered chelate rings. At pH* 7 the reaction of [AuCl4]- with Gly-Gly-L-His follows a different course, apparently involving the formation of AuIII cross-linked polymers. The anion [PdCl4]2- reacts rapidly with Gly-Gly-L-His also at pH* 2, and forms a similar square-planar complex [PdII(Gly-Gly-L-His-H-2)]·1.5H2O 2 involving the terminal NH2 [Pd-N 2.058(7) {\AA}], two deprotonated amide nitrogens [Pd-N- 1.943(7), 1.983(6) {\AA}] and HisδN [Pd-N 2.016(6) {\AA}]. By potentiometry, pKa values of 2.58 (CO2H), 8.63 (HisεNH, 'pyrrole nitrogen') and 11.50 (co-ordinated NH2) for 1 and 11.30 (HisεNH) for 2 were determined and confirmed by 1H NMR spectroscopy.",
author = "Best, {Sabine L.} and Chattopadhyay, {Tapan K.} and Djuran, {Milos I.} and Palmer, {Rex A.} and Sadler, {Peter J.} and I. S{\'o}v{\'a}g{\'o} and K. V{\'a}rnagy",
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T1 - Gold(III) and palladium(II) complexes of glycylglycyl-L-histidine

T2 - Crystal structures of [AuIII(Gly-Gly-L-His-H-2)]Cl·H2O and [PdII(Gly-Gly-L-His-H-2)]·1.5H2O and HisεNH deprotonation

AU - Best, Sabine L.

AU - Chattopadhyay, Tapan K.

AU - Djuran, Milos I.

AU - Palmer, Rex A.

AU - Sadler, Peter J.

AU - Sóvágó, I.

AU - Várnagy, K.

PY - 1997/8/7

Y1 - 1997/8/7

N2 - Proton NMR studies show that [AuCl4]- reacts slowly with glycylglycyl-L-histidine (Gly-Gly-L-His) (t1/2 = 9.3 h at 310 K and pH* 2) in D2O at pH* (meter reading) values as low as 1.5 to form the stable complex [AuIII(Gly-Gly-L-His-H-2)]C1·O 1 via one intermediate. Complex 1 is shown by X-ray crystallography to be square-planar with gold bound to the terminal NH2 [Au-N 2.049(10) Å], two deprotonated amide nitrogens [Au-N- 1.941(9), 2.006(10) Å] and HisδN [Au-N 2.038(9) Å] giving one six-membered and two five-membered chelate rings. At pH* 7 the reaction of [AuCl4]- with Gly-Gly-L-His follows a different course, apparently involving the formation of AuIII cross-linked polymers. The anion [PdCl4]2- reacts rapidly with Gly-Gly-L-His also at pH* 2, and forms a similar square-planar complex [PdII(Gly-Gly-L-His-H-2)]·1.5H2O 2 involving the terminal NH2 [Pd-N 2.058(7) Å], two deprotonated amide nitrogens [Pd-N- 1.943(7), 1.983(6) Å] and HisδN [Pd-N 2.016(6) Å]. By potentiometry, pKa values of 2.58 (CO2H), 8.63 (HisεNH, 'pyrrole nitrogen') and 11.50 (co-ordinated NH2) for 1 and 11.30 (HisεNH) for 2 were determined and confirmed by 1H NMR spectroscopy.

AB - Proton NMR studies show that [AuCl4]- reacts slowly with glycylglycyl-L-histidine (Gly-Gly-L-His) (t1/2 = 9.3 h at 310 K and pH* 2) in D2O at pH* (meter reading) values as low as 1.5 to form the stable complex [AuIII(Gly-Gly-L-His-H-2)]C1·O 1 via one intermediate. Complex 1 is shown by X-ray crystallography to be square-planar with gold bound to the terminal NH2 [Au-N 2.049(10) Å], two deprotonated amide nitrogens [Au-N- 1.941(9), 2.006(10) Å] and HisδN [Au-N 2.038(9) Å] giving one six-membered and two five-membered chelate rings. At pH* 7 the reaction of [AuCl4]- with Gly-Gly-L-His follows a different course, apparently involving the formation of AuIII cross-linked polymers. The anion [PdCl4]2- reacts rapidly with Gly-Gly-L-His also at pH* 2, and forms a similar square-planar complex [PdII(Gly-Gly-L-His-H-2)]·1.5H2O 2 involving the terminal NH2 [Pd-N 2.058(7) Å], two deprotonated amide nitrogens [Pd-N- 1.943(7), 1.983(6) Å] and HisδN [Pd-N 2.016(6) Å]. By potentiometry, pKa values of 2.58 (CO2H), 8.63 (HisεNH, 'pyrrole nitrogen') and 11.50 (co-ordinated NH2) for 1 and 11.30 (HisεNH) for 2 were determined and confirmed by 1H NMR spectroscopy.

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