The mechanism for the oxidation of 3'-dGMP by [PtCl₄(dach)] (dach = diaminocyclohexane) in the presence of [PtCl₂(dach)] has been investigated using density functional theory. We find that the initial complexation, i.e., the formation of [PtCl₃(dach)(3'-dGMP)], is greatly assisted by the reaction of the encounter pair [PtCl₂(dach)···3'-dGMP] with [PtCl₄(dach)], leading to migration of an axial chlorine ligand from platinum(IV) to platinum(II). A dinuclear platinum(II)/platinum(IV) intermediate could not be found, but the reaction is predicted to pass through a platinum(III)/platinum(III) transition structure. A cyclization process, i.e., C8-O bond formation, from [PtCl₃(dach)(3'-dGMP)] occurs through an intriguing phosphate-water-assisted deprotonation reaction, analogous to the opposite of a proton shuttle mechanism. Followed by this, the guanine moiety is oxidized via dissociation of the Pt^IV-Cl_ax bond, and the cyclic ether product is finally formed after deprotonation. We have provided rationalizations, including molecular orbital explanations, for the key steps in the process. Our results help to explain the effect of [PtCl₄(dach)] on the complexation step and the effect of a strong hydroxide base on the cyclization reaction. The overall reaction cycle is intricate and involves autocatalysis by a platinum(II) species.

Item Type:	Refereed Article
Research Division:	Chemical Sciences
Research Group:	Inorganic Chemistry
Research Field:	Bioinorganic Chemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Ariafard, A (Associate Professor Alireza Ariafard)
Author:	Canty, AJ (Professor Allan Canty)
Author:	Yates, BF (Professor Brian Yates)
ID Code:	88259
Year Published:	2013
Web of Science® Times Cited:	20
Deposited By:	Chemistry
Deposited On:	2014-01-23
Last Modified:	2014-06-17
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