Reaction of platinum(II) diamine and triamine complexes with selenomethionine

We have reacted [Pt(dien)Cl]Cl, [Pt(en)(D(2)O)(2)](2+), and [Pt(Me(4)en)(D(2)O)(2)](2+) [Me(4)en = N, N, N', N ''-tetramethylethylenediamine] with selenomethionine (SeMet). When [Pt(dien) Cl] Cl is reacted with SeMet, [Pt(dien)(SeMet- Se)] 2+ is formed; two Se-CH(3) resonances are observed due to the different chiralities at the Se atom upon platination. In a reaction of [Pt(dien) Cl] Cl with an equimolar mixture of SeMet and Met, the SeMet product forms more quickly though a slow equilibrium with approximately equal amounts of both products is reached. [Pt(Me(4)en)(D(2)O)(2)](2+) reacts with SeMet to form [Pt(Me4en)(SeMet- Se)(D2O)] 2+ initially but forms [Pt(Me(4)en)(SeMet-Se, N)]+ ultimately. One stereoisomer of the chelate, assigned to the R chirality at the Se atom, dominates within the first few minutes of reaction. [Pt(en)(D(2)O)(2)](2+) forms a variety of products depending on reaction stoichiometry; when one equivalent or less of SeMet is added, the dominant product is [Pt(en)(SeMet-Se, N)](+). In the presence of excess SeMet, [Pt(en)(SeMet-Se)(2)](2+) is the dominant initially, but displacement of the en ligand occurs leading to [Pt(SeMet- Se, N)(2)] as the eventual product. Displacement of the en ligand from [Pt(en)(SeMet- Se, N)](+) does not occur. In reactions of K(2)PtCl(4) with two equivalents of SeMet, [Pt(SeMet- Se, N)(2)] is formed, and three sets of resonances are observed due to different chiralities at the Se atoms. Only the cis geometric isomers are observed by (1)H and (195)Pt NMR spectroscopy. (C) 2011 Elsevier B.V. All rights reserved.