Tuning Reactivity of Platinum(II) Complexes

ln(k 2(3 rd ) /T)
-11.5
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
0.00320 0.00325 0.00330 0.00335 0.00340 0.00345 0.00350
1/T, K -1
29
DMTU
TMTU
TU
Figure 5.11: Plots of ln(k2/ T) versus 1/T for the third reaction step of pmn with a
5.4 Discussion
series nucleophiles in the temperature range 15-35 °C, I = 0.10 M (0.01 M
HClO4, adjusted with NaClO4).
In the current study, the investigated complexes are characterized by the two Pt(II)
centres that are linked by rigid aromatic ligands of varying Pt---Pt distances due to
different positions of the N atoms in the heterocyclic ring. The dinuclear Pt(II)
complexes can be classified into two groups as monocyclic diazines: pzn, pmn, and pdn;
and benzodiazines- qzn and pht. From the DFT calculations, the distance separating the
two Pt(II) centres varies in the decreasing order: pzn (7.063) > pmn (6.174) > qzn
(6.040) > pdn (4.022) > pht (3.905 Å), respectively. In addition, the complex is
symmetry i.e. C2v point group symmetry for pmn, pdn, and pht, and D2h for pzn, while
qzn has a C1 symmetry (Figure 5.1).
The kinetic data in Table 5.3 shows that the lability of the aqua ligands is dependent on
the nature, structural geometric, as well as the distance between the N atoms of the
coordinated diazine-bridging ligand. A comparison of the k2-values in Table 5.3 reveals
the order of reactivity of the complexes to be pzn > qzn > pmn > pdn > pht. This order