1. When a 1 mM solution of [Pd(en)(NO3)2] in D20 is treated with one molar equivalent of ligand L1, a single species P w

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1 When A 1 Mm Solution Of Pd En No3 2 In D20 Is Treated With One Molar Equivalent Of Ligand L1 A Single Species P W 1 (100.01 KiB) Viewed 46 times

1. When a 1 mM solution of [Pd(en)(NO3)2] in D20 is treated with one molar equivalent of ligand L1, a single species P with the 'H NMR spectrum shown below (1A) is obtained. Mass spectrometry analysis (positive ion mode) showed peaks at m/z = 1040.2, 489.1, and 305.4. COONa HE PO(NO) [Pd(en)(NO3)2] (MW = 290.5) G L1 (MW = 260.3) (1A): 1 mM L1 + 1 eq. [Pd(en)(NO3)2] Hz H لال (1B): 5 mM L1 + 1 eq. [Pd(en)(NO3)2] HE HE' H Hs' "IN (10): 20 mM L1 + 1 eq. [Pd(en)(NO3)2] Hs' Hz H' H' H Hz' (10): 50 mM L1 + 1 eq. [Pd(en)(NO3)2] H Hy' H' H hl H' Hz L ل 8.5 16 8 80 55 7.5 70 65 Chemical shift (p.p.m.)

Propose a structure of P and suggest how the MS data can be assigned. (3 marks) (b) From both thermodynamic and kinetic points of view, discuss why only a single product (i.e. P) was formed instead of a mixture of products of varying ligand-metal stoichiometry (5 marks) Sodium (p-methoxyphenyl)acetate (G) was found to bind to the cavity of Pin D.O. Suggest the possible non-covalent interactions involved in the binding. Also propose a physical method for studying the thermodynamic parameters and (ii) stoichiometry of the binding. Include in your answer the necessary details to show how the required information can be obtained by your suggested physical method. (5 marks) (d) Upon increasing the concentration of Pin D.O, a new species which is a catenane formed from two molecules of P was obtained. The 'H NMR spectra obtained from different concentrations of the building blocks are shown above in (1B) to (ID). Signals from C are denoted as H', Hz' and H='. (1) What is a catenane? How would you explain the formation of C from P? (2 marks) (ii) Explain the spectral observations in the concentration-dependent NMR studies. (3 marks) (ii) P' is obtained by replacing the Pd(II) ions in P by Pt(II)ions. Explain if you would expect a similar catenane to be formed upon increasing the concentration of P'. If not, suggest an experimental condition that can facilitate the formation of such a catenane from P". (2 marks)