Quick Search:

uzh logo
Browse by:

Zurich Open Repository and Archive

Maintenance: Tuesday, July the 26th 2016, 07:00-10:00

ZORA's new graphical user interface will be relaunched (For further infos watch out slideshow ZORA: Neues Look & Feel). There will be short interrupts on ZORA Service between 07:00am and 10:00 am. Please be patient.

Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-1742

Brüning, W; Freisinger, E; Sabat, M; Sigel, R K O; Lippert, B (2002). N1 and N3 linkage isomers of neutral and deprotonated cytosine with trans-[(CH3NH2)2PtII]. Chemistry - A European Journal, 8(20):4681-4692.

[img]Accepted Version
PDF - Registered users only
View at publisher


A series of complexes obtained from the reaction of trans-[(CH3NH2)2PtII] with unsubstituted cytosine (CH) and its anion (C), respectively, has been prepared and isolated or detected in solution: trans-[Pt(CH3NH2)2(CH-N3)Cl]Cl.H2O (1), trans-[Pt(CH3NH2)2(CH-N3)2](ClO4)2 (1a), trans-[Pt(CH3NH2)2(C-N3)2].2H2O (1b), trans-[Pt(CH3NH2)2(CH-N3)2](ClO4)(2).2DMSO (1c), trans-[Pt(CH3NH2)2(CH-N1)2] (NO3)(2).3H2O (2a), trans-[Pt(CH3NH2)2(C-N1)2].2H2O (2b), trans-[Pt(CH3NH2)2(CH-N1)(CH-N3)](ClO4)2 (3a), trans-[Pt(CH3NH2)2(C-N1)(C-N3)] (3b), and trans-[Pt(CH3NH2)2(N1-CN3)(N3-C-N1)Cu(OH)]ClO(4).1.2H2O (4). X-ray crystal structures of all these compounds, except 3a and 3b, are reported. Complex 2a is of particular interest in that it contains the rarer of the two 2-oxo-4-amino tautomer forms of cytosine, namely that with the N3 position protonated. Since the effect of PtII on the geometry of the nucleobase is minimal, bond lengths and angles of CH in 2a reflect, to a first approximation, those of the free rare tautomer. Compared to the preferred 2-oxo-4-amino tautomer (N1 site protonated) of CH, the rare tautomer in 2a differs particularly in internal ring angles (7-11 sigma). Formation of compounds containing the rare CH tautomers on a preparative scale can be achieved by a detour (reaction of PtII with the cytosine anion, followed by cytosine reprotonation) or by linkage isomerization (N3-->N1) under alkaline reaction conditions. Surprisingly, in water and over a wide pH range, N1 linkage isomers (3a, 2a) form in considerably higher amounts than can be expected on the basis of the tautomer equilibrium. This is particularly true for the pH range in which the cytosine is present as a neutral species and implies that complexation of the minor tautomer is considerably promoted. Deprotonation of the rare CH tautomers in 2a occurs with pKa values of 6.07 +/- 0.18 (1 sigma) and 7.09 +/- 0.11 (1 sigma). This value compares with pKa 9.06 +/- 0.09 (1 sigma) (average of both ligands) in 1a.


25 citations in Web of Science®
29 citations in Scopus®
Google Scholar™



1 download since deposited on 11 Feb 2008
0 downloads since 12 months

Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Date:18 October 2002
Deposited On:11 Feb 2008 12:25
Last Modified:05 Apr 2016 12:20
Publisher DOI:10.1002/1521-3765(20021018)8:20<4681::AID-CHEM4681>3.0.CO;2-P
PubMed ID:12561109

Users (please log in): suggest update or correction for this item

Repository Staff Only: item control page