Tuning Reactivity of Platinum(II) Complexes

ButPt, HexPt, OctPt and DecPt, were optimised using the B3LYP 39 hybrid density
functional and the LACVP** (Los Alamos Core Valence Potentials) 40 basis set, using the
Spartan`04 for windows computational software package. All structures were
characterised as cationic species of formal charges of 4+.
7.2.4 Preparation of Aqueous Complex Solutions
The desired solutions of the diaqua complexes were prepared by removal of Cl - with Ag +,
(1: 1.98 molar ratio of the chloro complexes (EnPt to DecPt) to silver perchlorate) in
0.1M HClO4, as described in the literature for Pt(II) aqua complexes. 41 The mixture was
vigorously stirred at 50°C for 24h in the dark. After cooling on ice cold water, the
precipitated AgCl was filtered off. The resulting aqueous solution was brought to a final
complex concentration of respectively, 1.09 x 10 -4, 5.33 x 10 -4, 2.29 x 10 -4, 1.17 x 10 -3,
1.34 x 10 -3 and 1.00 x 10 -4 M for EnPt, PropPt, ButPt, HexPt, OctPt and DecPt, using
0.1M HClO4 and stored in a fridge until use. For all the kinetic investigations, the pH of
the solutions was maintained at ca. 2.0, in order to guarantee the presence of only the
diaqua form of the complexes. Since perchlorate ion, (ClO4 ¯), does not coordinate to
Pt(II), 42 the ionic strength was adjusted to 0.1M using 0.1M NaClO4/HClO4 solution. A
series of nucleophile concentrations in the order: 20, 40, 60, 80 and 100-fold excess to
the metal complex concentration were obtained using the 0.1M NaClO4/HClO4 solution.
8