The study of macrocyclic ligands for complexation of alkali metals (macrobicyclic polyether cryptands) and transition metals (tetraaza macrocycles) is reported. The synthesis of a new bis(phosphotriester) macrobicyclic polyether cryptand, O = P (O(CH$\sb2)\sb2\rm O(CH\sb2)\sb2O(CH\sb2)\sb2O\rbrack\sb3$ P = O, 1, called phosphocrypt, and its acyclic tripodal precursor O = P (O(CH$\sb2)\sb2\rm O(CH\sb2)\sb2O(CH\sb2)\sb2OH\rbrack\sb3$, 2, is described. Aqueous stability constants (K$\sb{\rm s}$) measured with a cation selective electrode with potassium and rubidium are 10$\sp{3.7}$ and 10$\sp{3.6}$ for 1, and are 10$\sp{3.6}$ and 10$\sp{3.0}$ for 2, respectively. The K$\sb{\rm s}$ values for phosphocrypt are 1000 fold greater than comparably sized nitrogen bridgehead cryptands. $\sp1$H and $\sp{13}$C NMR indicate 1 is flexible at 20$\sp\circ$C. Molecular mechanics calculations confirm the flexibility of 1. Also reported are the synthesis and characterization of (1) a new mixed-valence bimetallic ruthenium complex, Ru$\sb2\rm (C\sb{20}H\sb{36}N\sb8)Cl\sb{4}\sp{+}$, 3, that contains a cross-conjugated bridge that links two tetraaza macrocycles; and (2) the formation, physical properties, and reduction chemistry of a new iron $\beta$-diimine keto macrocyclic complex, Fe(C$\rm \sb{10}H\sb{18}N\sb{4}O)(CH\sb3CN)\sb{2}\sp{2+},$ 4. The ruthenium dimer 3 was formed by oxidative dehydrogenation of Ru(C$\rm\sb{10}H\sb{24}N\sb4)(Cl\sb2)\sp+$ and its mass was determined by positive ion fast atom bombardment mass spectrometry. The binuclear species 3 is assigned as a Robin and Day strongly coupled class III mixed-valence species based on cyclic voltammetry, electronic spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XPS photopeaks of 3 for the binding energies from the Ru 3p$\sb{1/2}$ and Ru 3p$\sb{3/2}$ regions show only a single peak, indicating the unpaired electron is delocalized on the short (10$\sp{-17}$ s) timescale of the XPS experiment. The keto complex 4 was formed in high yields ($>$90%) from the reaction of Fe$\rm\sb2(C\sb{20}H\sb{36}N\sb8)(CH\sb3CN)\sb{4}\sp{4+}$, 5, (the diiron analog of 3) with molecular oxygen. Its mass was determined by electrospray mass spectrometry and its structure by NMR spectroscopy ($\sp1$H, $\sp{13}$C, COSY, NOE DIFF). The complex is rigid at room temperature in CD$\sb3$CN and this allows the assignment of the ten distinct protons. Reduction of the keto group in 4 under anaerobic conditions, followed by aerobic oxidation, leads to the reformation of 5.
| Identifer | oai:union.ndltd.org:pacific.edu/oai:scholarlycommons.pacific.edu:uop_etds-3666 |
| Date | 01 January 1994 |
| Creators | Allan, Christian Bruce |
| Publisher | Scholarly Commons |
| Source Sets | University of the Pacific |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | University of the Pacific Theses and Dissertations |
Page generated in 0.0019 seconds