Proton magnetic resonance studies of amino acid complexes of platinum(II). I. Synthesis, spectral interpretation, and conformational implications

Erickson, Luther E.; McDonald, John W.; Howie, John K.; Clow, Roger P.

doi:10.1021/ja01025a022

Cited by 87 publications

(15 citation statements)

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“…The three-bond coupling ( 3 J Pt,H ) between the Pt and the H atoms on the asymmetric carbons (C 2,4 ) is ∼54 Hz in set X but less than 15 Hz in set Y. This major difference may be due to the Karplus type angular dependence of 3 J Pt,H shows a chelate ring viewed down one of the N−C bonds in the chair and skew conformations (a) and in the boat conformation (b).…”

Section: Resultsmentioning

confidence: 99%

Factors Influencing the Configuration and Conformation of Diamine Chelate Rings in Platinum(II) Compounds: 2,4-Bis(methylamino)pentane Complexes

et al. 1997

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Complexes of the type [PtX(2)(Me(2)DAP)] (Me(2)DAP = 2,4-bis(methylamino)pentane) have been prepared and studied by (1)H NMR spectroscopy, molecular mechanics/dynamics (MMD) calculations, and X-ray crystallography. The coordinated Me(2)DAP ligand has four asymmetric centers. Complexes with an enantiomeric form of the ligand (e.g., RR-Me(2)DAP, RR being the configurations of the two asymmetric carbons) have three possible configurations, namely, SRRR, RRRR, and SRRS at N, C, C, and N, respectively. Indeed these three isomers were obtained in respective ratios of 9:1: approximately 0 for X = I(-) and of 7:3:1 for X = Cl(-). Complexes with the meso ligand (RS-Me(2)DAP) have four possible configurations, i.e., SRSR, RRSS, RRSR, and SRSS at N, C, C, and N, respectively (the latter two constitute an enantiomeric pair). Only the two symmetrical isomers were obtained in the ratios of 9:1 for X = I(-) and 1:1 for X = Cl(-). In addition, the preferred chelate ring conformations in solution (CDCl(3)) were determined to be the following: delta-chair (SRRR), lambda-skew (RRRR), fluxional chair (SRRS), fluxional skew (SRSR), and lambda-chair (RRSS). This information was used to assess the contributions of intra- and interligand interactions to determine the conformational stability. MMD calculations employing the AMBER force field [as modified by Yao et al. (Yao, S.; Plastaras, J. P.; Marzilli, L. G. Inorg. Chem. 1994, 33, 6061) and extended to include parameters for the Cl(-) ligands] provided minimum-energy structures for all five X = Cl(-) complexes. These structures agreed well with the experimentally determined solution conformations except for SRSR, which had a lowest energy delta-chair instead of skew conformation. X-ray structural studies of the SRSR species (X = Cl(-) and X = I(-)) confirmed the delta-chair conformation. The results suggest that an equatorial N-methyl group has nonbonded clashes with the cis chloride ligand; therefore, axial N-methyl groups are favored. However, in solution, the solvent and entropy (connected with fluxionality of conformers) are factors which, to some degree, can overcome the interligand steric interaction.

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Section: Resultsmentioning

confidence: 99%

Factors Influencing the Configuration and Conformation of Diamine Chelate Rings in Platinum(II) Compounds: 2,4-Bis(methylamino)pentane Complexes

et al. 1997

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“…The major product of this reaction at 1.5 < pH < 5.0 is a chelate complex of type D. As shown in this complex the peptide co-ordinates to the palladium() via imidazole N-3 and amino nitrogen atoms. 29,30 In the reaction between cis-[PdCl 2 (-HMet-S,N)] and His-Gly at 1.5 < pH < 5.0 the complexes of types A and D spontaneously formed. We did not observe opening of the -HMet chelate even at pH < 1.5.…”

Section: Reactions Of Palladium(ii) Complexes With His-glymentioning

confidence: 99%

Dependence of hydrolytic cleavage of histidine-containing peptides by palladium(II) aqua complexes on the co-ordination modes of the peptides

Milinković¹,

Parac²,

Djuran³

et al. 1997

J. Chem. Soc., Dalton Trans.

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“…(xvi) Tetrammineplatinum (II) chloride, [Pt(NH.,)4]Cl2. Prepared as by Keller (1946) Erickson et al (1968) was employed. An aqueous solution of an equimolar mixture of K2[PtCl4] and glycine was heated on a steam bath and the falling pH maintained at 4 by the addition of I equivalent of KOH per mole of glycine.…”

Section: Preparation Of Complexesmentioning

confidence: 99%

Immediate (type I) allergic responses to platinum compounds

Cleare

Hughes

Jacoby³

et al. 1976

Clin Experimental Allergy

140

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A series of platinum complexes has beeti used for allergy tests in a tiumber of platinum refinery workers who are known to be sensitive to hexachloroplatinate ([PtCl(,]^^) salts. The results show that the allergy-eliciting compounds are confined to a very small group of ionic complexes containing reactive halogen ligands. Neutral complexes and those containing more strongly bound ligands are totally inactive. These variations in activity are interpreted in terms of established kinetic and thermodynamic parameters.

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Proton magnetic resonance studies of amino acid complexes of platinum(II). I. Synthesis, spectral interpretation, and conformational implications

Cited by 87 publications

References 0 publications

Factors Influencing the Configuration and Conformation of Diamine Chelate Rings in Platinum(II) Compounds: 2,4-Bis(methylamino)pentane Complexes

Factors Influencing the Configuration and Conformation of Diamine Chelate Rings in Platinum(II) Compounds: 2,4-Bis(methylamino)pentane Complexes

Dependence of hydrolytic cleavage of histidine-containing peptides by palladium(II) aqua complexes on the co-ordination modes of the peptides

Immediate (type I) allergic responses to platinum compounds

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