29.07.2013 Views

Tuning Reactivity of Platinum(II) Complexes

Tuning Reactivity of Platinum(II) Complexes

Tuning Reactivity of Platinum(II) Complexes

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Table <strong>of</strong> Contents-7<br />

Chapter 7 .................................................................................................................................................................... 1<br />

The Influence <strong>of</strong> α,ω-Diamine Linker on Ligand Substitution <strong>of</strong> Dinuclear Pt(<strong>II</strong>)<br />

<strong>Complexes</strong>: A Thermodynamic and Kinetic Study .................................................................................... 1<br />

7.0 Abstract ........................................................................................................................................................... 1<br />

7.1 Introduction .................................................................................................................................................. 2<br />

7.2 Experimental Section ............................................................................................................................... 4<br />

7.2.1 Synthesis <strong>of</strong> compounds Pt (EnPt-DecPt) .................................................................................. 5<br />

7.2.2 Physical measurements ...................................................................................................................... 7<br />

7.2.3 Computational Details ......................................................................................................................... 7<br />

7.2.4 Preparation <strong>of</strong> aqueous complex solutions ............................................................................... 8<br />

7.2.8 pKa titrations <strong>of</strong> the diaqua complexes ........................................................................................ 9<br />

7.2.6 Kinetic Measurements ......................................................................................................................... 9<br />

7.3 Results .......................................................................................................................................................... 10<br />

7.3.1 DFT Calculations .................................................................................................................................. 10<br />

7.3.2 Acidity <strong>of</strong> the diaqua complexes .................................................................................................. 13<br />

7.3.3 Kinetics ..................................................................................................................................................... 15<br />

7.3.4 Activation parameters ...................................................................................................................... 24<br />

7.4 Discussion ................................................................................................................................................... 25<br />

7.4.1 pKa <strong>of</strong> the diaqua complexes .......................................................................................................... 25<br />

7.4.2 Substitution process .......................................................................................................................... 26<br />

7.5 Conclusion .................................................................................................................................................. 28<br />

List <strong>of</strong> Figures<br />

Figure 7.1 Density Functional theoretical (DFT) minimum energy structures, HOMO and LUMO<br />

frontier molecular orbitals for investigated diaqua Pt(<strong>II</strong>) complexes. ............................................ 12<br />

Figure 7.2 HOMO-LUMO Energy gap as a function <strong>of</strong> number <strong>of</strong> carbons for the diaqua<br />

complexes ............................................................................................................................................. 13<br />

Figure 7.3 UV-Vis spectra <strong>of</strong> the diaqua OctPt complex recorded as a function <strong>of</strong> pH in the range<br />

<strong>of</strong> 2- 10; I = 0.10 M (NaClO4), T = 25 ºC. Inset: Plot <strong>of</strong> absorbance vs. pH at 241 nm. ................... 14<br />

Figure 4: An array <strong>of</strong> 1H NMR spectra <strong>of</strong> HexPt-Cl (showing methylene (CH2) protons only)<br />

acquired during the reaction with 6 equiv. TU in D2O, at 30 °C, with spectrum “a” at zero time<br />

and “d” after 12.0 h reaction time, respectively. Where Ha = (CH2, 1/6), Hb = (CH2, 2/5) and Hc =<br />

(CH2, 3/4) represent the methylene protons as shown in the structure for starting complex<br />

above, showing the formation <strong>of</strong> substituted thiourea products described in Scheme 7.4. The<br />

protons Ha’/Ha” are (CH2, 1/6), Hb’/Hb” are (CH2, 2/5) and Hc’/Hc” are (CH2, 3/4) protons for<br />

cis–[{Pt(TU)(NH3)2}2–µ–NH2(CH2)6NH2] 4+ and cis–[{Pt(TU)2(NH3)}2–µ–NH2(CH2)6NH2] 4+ species,<br />

respectively. * are unknown impurities in solution or solvent. ....................................................... 17<br />

i

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!