We prepared a seties of tridentate amido diphosphine ligands, including symmetrical [N(o-C6H4PR2)2]- ([R-PNP]- ; R = Ph, iPr, Cy) and unsymmetrical [N(o-C6H4PPh2) (o-C6H4PiPr2)]-. Deprotonation of neutral ligands, H[R-PNP] ( R = Ph, iPr, Cy) or H[Ph-PNP-iPr], with n-BuLi in ether solutions at -35oC produced the lithium complexes, [R-PNP]Li(solv)n ( R = Ph, iPr, Cy; solv = THF, OEt2; n = 1,2) or [Ph-PNP-iPr]Li(solv)n (solv = THF, OEt2; n = 1,2), respectively. The reactions of the lithium complexes or neutral ligands with NiCl2(DME) in THF solutions generated nickel(II) chloride complexes, [R-PNP]NiCl ( R = Ph, iPr, Cy) or [Ph-PNP-iPr]NiCl, which was then reacted with a variety of Grignard reagents to afford the corresponding hydrocarbyl complexes. Of particular interest among the compounds isolated are alkyl complexes that contain £]−hydrogen atoms. The metathetical reactions of nickel(II) chloride complexes with LiNHPh, NaOPh, NaSPh, or NaOtBu, respectively, produced the correspounding nickel anilide, nickel phenolate, nickel thiophenolate and nickel tert-butoxide derivatives. Protonolysis studies of nickel(II)-heteroatom complexes revealed the basic reactivity of these £k-donor ligands. The basicity follows the order OtBu > NHPh > OPh > SPh. Treatment of Ni(COD)2 (COD = cycloocta-1,5-diene) with neutral ligands produced the correspounding four-corrdinate nickel hydride complexes, [R-PNP]NiH (R = Ph, iPr, Cy) or [Ph-PNP-iPr]NiH. The olefin insertion reactions of [iPr-PNP]NiH or [Ph-PNP-iPr]NiH with ethylene, 1-hexene, and norbornene, respectively, generated the corresponding ethyl, n-hexyl, and 2-norbornyl complexes. The formation of [iPr-PNP]Ni(n-hexyl) or [Ph-PNP-iPr]Ni(n-hexyl) is indicative of exclusive 1,2-insertion of 1-hexene. In contrast, styrene inserts into the Ni-H bond of [Ph-PNP-iPr]NiH in an exclusively 2,1-manner to afford [Ph-PNP-iPr]NiCH(Me)Ph. The selective 2,1-insertion products [R-PNP]NiCH(Me)CO2Me (R = Ph, iPr, Cy) or [Ph-PNP-iPr]NiCH(Me)CO2Me were also isolated from the reactions of methyl acrylate with the corresponding nickel hydride complexes. The effects of the phosphorus and olefin substituent on the reactivity and regioselectivity of the olefin insertion reactions are discussed. We also prepared nickel acyl complexes and nickel complexes catalyzed C-N bond formation. In addition to solution NMR spectroscopic data for all new compounds. X-ray diffraction revealed solid structures. A series of five-coordinate aluminum complexes supported by o-phenylene - derived amido diphosphine ligands have been prepared and structurally characterized. Alkane elimination reactions of trialkylaluminum with neutral ligands, H[R-PNP] ( R = Ph, iPr) and H[Ph-PNP-iPr] in toluene solution at -35oC respectively produced the corresponding dialkyl complexes [iPr-PNP]AlR'2, [Ph-PNP]AlR'2 and [iPr-PNP-Ph]AlR'2 (R' = Me, Et, iBu) in high isolated yield. The dihydride complexes [iPr-PNP] AlH2, [Ph-PNP]AlH2 and [iPr-PNP-Ph]AlH2 prepared in one-pot reactions of in situ prepared dichloride precursors with LiAlH4 in THF at room temperature. X-ray diffraction studies revealed a distorted trigonal-bipyramidal structure for these molecules in which the two phosphorus donors are mutually trans. The solution structures of these complexes were all characterized by 1H, 13C, and 31P NMR spectroscopy. The NMR data are indicative of solution C2 symmetry for [iPr-PNP]- and [Ph-PNP]- complexes, whereas they are indicative of C1 for [iPr-PNP-Ph]- derivatives. The 1H NMR spectra of [iPr-PNP]AlR'2, [Ph-PNP]AlR'2 and [iPr-PNP-Ph]AlR'2 (R' = Et, iBu) revealed diastereotopy for the £\-hydrogen atoms in these molecules.

This thesis presents the basic concepts of electronic structure theory and the chemical properties of mercury. The theoretical foundation of DFT and the consequences of relativity are also introduced. The electronic structure of Hg(II) ions, [Hg(L)n(H2O)m]q (L = HO-, Cl-, HS-, S2-) has been studied. We show, in this thesis, that the charge transfer (that is calculated from the hard-soft-acid-base principle (Pearson’s principle)), the total NBO charge and the interaction energies are strongly correlated. Our studies indicate the effect of the solvent on the global electrophilicity, the charge transfer and consequently the interaction strength between Hg(II) and ligand L. The formation constants, logK, of Hg2+−complexes are calculated. The procedure that we follow in this thesis to calculate the formation constants, logK’s, are in good agreement with the extrapolated experimental values. We introduce and explain why it is important adding water molecules explicitly during the calculations of the logK. The recommended logK value of HgS is 27.2. We examined two different types of organic compounds as sensors for heavy metal ions: lumazine (Lm) and 6-thienyllumazine (TLm). We found that the simple calculation of pKa values using DFT methods and implicit solvent models failed to reproduce the experimental values. However, calculated orbital energies and gas phase acidities both indicate that the compound TLm is inherently more acidic than the parent species Lm. We demonstrate that: (1) we need to take in our consideration the population of each tautomer and conformer during the calculations of the pKa values, and (2) thienyl group has indirect effect on the acidity of the proton on N1 in the uracil ring. Last but not least, the fluorescence spectrum of the sensors (L) and their [(L)nM(H2O)m]2+ complexes (L = Lumazine (Lm) and 6-thienyllumazine (TLm) and M = Cd2+and Hg2+) are calculated using time dependent DFT (TDDFT). The results show that TDDFT is in good agreement with experimental results. This chapter provides a new concept in the design of fluorescence turn-on/off sensors that has wider applicability for other systems. Finally, we provide a summary of the works compiled in this thesis and an outlook on potential future work. / October 2015