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Tuning Reactivity of Platinum(II) Complexes

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H3N<br />

6 eq TU<br />

0 eq TU<br />

Ha<br />

NH3<br />

Ha Cl<br />

TU<br />

Ha'<br />

Ha’<br />

Pt Pt NH3<br />

N N +<br />

Cl<br />

Reactant<br />

Ha<br />

NH3<br />

9.4 9.3 9.2 9.1 9.0 8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 ppm<br />

18<br />

Excess<br />

Product<br />

Ha’<br />

Pt(TU)4<br />

(Equivalent to that <strong>of</strong> free ligand)<br />

Figure 5.3: 1 H NMR spectra <strong>of</strong> the reaction <strong>of</strong> cis-[{PtCl(NH3)2}2-μ-pzn] +2 and excess<br />

thiourea (TU). Charges omitted for clarity.<br />

The 1H NMR spectra <strong>of</strong> pdn showed two resonances Ha and Hb, at the beginning <strong>of</strong> the<br />

reaction. After 45 minutes a second set <strong>of</strong> non-symmetrical pyridazine resonances were<br />

clearly resolved (Figure 5.4) at δ = 9.19 ppm (pseudo triplet for equivalent H`a protons)<br />

and 7.83 ppm (pseudo triplet for equivalent H`b protons) 46 that are assigned to the<br />

degradation product, i.e. free pyridazine ligand. The proton labels are shown on the<br />

structures <strong>of</strong> the pdn complex and the free ligand presented below in Scheme 5.3.<br />

t > 48 h<br />

t = 0

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