Visser, Hendrik G.Venter, Johan A.Van der Merwe, Kina Ann2018-07-172018-07-172011-06http://hdl.handle.net/11660/8744English: The aim of the study was to synthesize several novel Co(II)-, Co(III)- and Cr(III) complexes using an O,O-bidentate ligand, methylene diphosphonate, and to characterize these complexes by various means. Characterization of the complexes was done by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy (NMR), single X-ray crystallography and X-ray photoelectron spectroscopy (XPS). The methylene diphosphonate ligand was selected as it is a ligand employed in a bone imaging agent in the radiopharmaceutical sector. Little is known about the structure and coordination chemistry of metal complexes with methylene diphosphonate. Single crystal X-ray crystallographic structure determinations of six new structures were completed: (1) Pyridinium diaquabis(methylenediphosphonato)chromate(III) tetrahydrate (2) Potassium diaquabis(methylenediphosphonato)cobaltate(III) (3) Potassium diaquadihydroxy(methylenediphosphonato)cobaltate(III) (4) Diammonium diaquabis(methylenediphosphonato)cobaltate(II) (5) Disodium diaquabis(methylenediphosphonato)cobaltate(II) dihydrate (6) Dicesium diaquabis(methylenediphosphonato)cobaltate(II) Each complex has a slightly distorted octahedral geometry. The cobalt or chromium ion in each complex is coordinated to four oxygen atoms derived from two methylene diphosphonate ligands, except for K[Co(CH4O6P2)(OH)2(H2O)2] which has two oxygen atoms from one methylene diphosphonate ligand coordinated to it. In addition each complex has two aqueous molecules which are coordinated to the metal center. Two phosphonate oxygen atoms from the ligand, methylene diphosphonate define the equatorial plane, whereas the water molecules reside in the axial positions. See Table in full text PDF. These complexes correlate with other similar complexes but the occurrence of similar structures in literature is very limited, showing that this field is open to further study. We were unable to perform any meaningful studies on these complexes in solution due to its insolubility in water. The stability constants for the polyprotic ligand MDP were established by means of volumetric titrations. Three methodologies namely, the geometric method, the first derivative method and the second derivative method in combination with the program SPARC were employed to determine the protonation constants as well as the equivalence points. In order to investigate the effect of the ionic medium on the determination of the dissociation constants, it was decided to perform the volumetric titrations in an ionic medium of 0.1 M NaCl and compare these values with data obtained without any adjustments to the ionic medium, the temperature for all of the reactions was kept constant at 18.0 ºC. The Ka1 value could not be determined using the Compact Titrator G20 as it is unable to perform titrations below pH 2. The Ka2 value was 2.91(8) without and ionic medium and 2.95(1) with and ionic medium (0.1 M NaCl). The Ka3 value was 7.22(5) without and ionic medium and 6.81(5) with and ionic medium (0.1 M NaCl). The Ka4 value was 10.57(1) without and ionic medium and 10.41(2) with and ionic medium (0.1 M NaCl). These dissociation constants correlated to literature.Afrikaans: Die doel van die studie was die sintese van verskeie oorspronklike Co(II)-, Co(III)- en Cr(III) komplekse met die gebruik van `n O,O-bidentate ligand, metileen difosfonaat, en die karakterisering van hierdie komplekse deur verskillende tegnieke. Karakterisering van die komplekse is gedoen deur elementele analise, infrarooi spektroskopie, kernmagnetieseresonans (KMR) spektroskopie, enkelkristal X-straal kristallografie asook X-straal foto-elektron spektroskopie (XPS). Die metileen difosfonaat ligand is gekies aangesien dit gebruik word as `n ligand in `n been beeldingsagent in die radiofarmaseutiese bedryf. Die struktuur en koördinasiechemie van metaalkomplekse met metileen difosfonaat is redelik onbekend. Enkelkristal X-straal kristallografiese struktuurbepalings van ses nuwe strukture is voltooi: (1) Piridinium diakwabis(metileendifosfonato)chromaat(III) tetrahidrate (2) Kalium diakwabis(metileendifosfonato)kobaltaat(III) (3) Kalium diakwadihidroksie(metileendifosfonato)kobaltaat(III) (4) Diammonium diakwabis(metileendifosfonato)kobaltaat(II) (5) Dinatrium diakwabis(metileendifosfonato)kobaltaat(II) dihidrate (6) Disesium diakwabis(metileendifosfonato)kobaltaat(II) Elke kompleks het `n effens verwronge oktahedriese geometrie. Die kobalt of chroom ioon in elke kompleks is aan vier suurstofatome gekoördineer; afkomstig van twee metileen difosfonaat ligande, behalwe vir K[Co(CH4O6P2)(OH)2(H2O)2] wat twee suurstofatome van een metileen difosfonaat ligand daaraan gekoördineer het. Benewens die bogenoemde het elke kompleks twee akwa molekule aan die metaalsenter gekoördineer. Twee fosfonaat suurstofatome van die ligand, metileen difosfonaat definieer die ekwatoriale vlak, terwyl water molekule die aksiale posisies betrek. Sien Tabel in volteks PDF. Hierdie komplekse stem ooreen met ander soortgelyke komplekse maar die voorkoms van soortgelyke strukture in die literatuur is baie beperk, wat aantoon dat hierdie veld oop is vir verdere studiemoontlikhede. Geen betekenisvolle studies kon op hierdie komplekse in oplossing uit te voer nie as gevolg van hulle onoplosbaarheid in water. Die stabiliteitskonstantes vir die poliprotiese ligand MDP is vasgestel deur middel van volumtriese titrasies. Drie metodes, naamlik die geometriese metode, eerste afgeleide metode en die tweede afgeleide metode in kombinasie met die program SPARC is gebruik om die protoneringskonstantes sowel as die ewewigspunte te bepaal. Ten einde die effek van die ioniese medium op die bepaling van die dissosiasiekonstantes te ondersoek is daar besluit om die volumetriese titrasies in `n ioniese medium van 0.1 M NaCl uit te voer en hierdie waardes te vergelyk met data wat verkry is sonder enige aanpassing aan die ioniese medium; die temperatuur vir al die reaksies is konstant gehou by 18.0 ºC. Die Ka1 waarde kon nie vasgestel word met die Compact Titrator G20 nie aangesien dit nie in staat is om titrasies laer as pH 2 uit te voer nie. Die Ka2 waarde was 2.91(8) sonder `n ioniese medium en 2.95(1) met `n ioniese medium (0.1 M NaCl). Die Ka3 waarde was 7.22(5) sonder `n ioniese medium en 6.81(5) met `n ioniese medium (0.1 M NaCl). Die Ka4 waarde was 10.57(1) sonder `n ioniese medium en 10.41(2) met `n ioniese medium (0.1 M NaCl). Hierdie dissosiasiekonstantes stem ooreen met literatuur.enCobaltChromiumMethylene diphosphonateBidentate ligandBone imaging agentRadiopharmaceuticalPolyproticProtonation constantspKaDissertation (M.Sc. (Chemistry))--University of the Free State, 2011DissertationUniversity of the Free State