Tuning Reactivity of Platinum(II) Complexes

ambient temperature of 30°C. Values of 1H are given in δ (ppm) relative to
tetramethylsilane (δ = 0.00) and 195 Pt chemical shifts were externally referenced to
K2[PtCl6] in D2O. Mass spectrometric analyses were collected on Hewlett Packard LC-MS
using electron impact ionization (ESI-TOF).
5.2.4 Computational Details
In an effort to gain further insight into the role of the diazine bridging ligand in such
dinuclear Pt(II) complexes, the corresponding diaqua cationic complexes of total
charges of 4+ were optimized at the B3LYP/ 33LACVP** (Los Alamos Core Valence
pseudo-potentials set) 34 hybrid level, utilizing density functional computation method
(DFT), in gaseous phase. B3LYP relates to the hybrid functional Becke’s three parameter
formulation 33 which has been proven to be superior to traditional functionals. The
Spartan `04 for Windows ® quantum chemical software package was used.
5.2.5 Preparation of the Aqueous Complex Solutions
The chloro complexes were converted into aqua analogues in solution by addition of
1.98 equiv. AgClO4 using literature procedure. 35 Since perchlorate ions do not
coordinate to Pt(II) the kinetic investigations were studied at pH ca.2.0 to prevent
deprotonation of the aqua ligand, 36 and the ionic strength was adjusted to I = 0.10 M
(NaClO4 adjusted with perchloric acid). The resultant aqueous solutions were brought
to a final complex concentration of 1.34 x 10 -4, 1.0 x 10 -3, 9.20 x 10 -4, 1.79 x 10 -3 and
1.0 x 10 -3 M, respectively, for [{cis–PtOH2(NH3)2}2-–μ–pmn](ClO4)2 (pmn), [{cis–
PtOH2(NH3)2}2–μ–pdn](ClO4)2 (pdn), [{cis–PtOH2(NH3)2}2–μ–qzn](ClO4)2 (qzn),
[{cis–PtOH2(NH3)2}2–μ–pht](ClO4)2 (pht), and [{cis–PtOH2(NH3)2}2–μ–pzn](ClO4)2
(pzn). A series of nucleophile concentrations in the order: 20, 40, 60, 80 and 100-fold
excess of appropriate metal complex concentration, were prepared using the 0.10 M
NaClO4/HClO4, at pH ca.2.0.
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