Doctor of Philosophy
Prof. Dr. J. F. Corrigan
The Co2+ and Mn2+ complexes (N,N´-tmeda)Co(ESiMe3)2 (E = S, 1a; E = Se, 1b), (3,5-Me2C5H3N)2Co(ESiMe3)2 (E = S, 2a; E = Se, 2b), [Li(N,N´-tmeda)]2[(N,N´-tmeda)Mn5(μ-ESiMe3)2(ESiMe3)4(μ4-E)(μ3-E)2] (E = S, 3a; E = Se, 3b), [Li(N,N´-tmeda)]2[Mn(SSiMe3)4] (4), [Li(N,N´-tmeda)]4[Mn4(SeSiMe3)4(μ3-Se)4] (5), and [Li(N,N´-tmeda)]4[Mn(Se4)3] (6) have been isolated from reactions of Li[ESiMe3] and the chloride salts of these metals. The treatment of (N,N´-tmeda)CoCl2 with two equivalents of Li[ESiMe3] (E = S, Se) yields 1a and 1b, respectively, whereas similar reactions with MnCl2 yield the polynuclear complexes 3a (E = S) and 3b (E = Se). The selective preparation of the mononuclear complex 4 is achieved by increasing the reaction ratios of Li[SSiMe3] to MnCl2 to 4:1. Single crystal X-ray analysis of complexes 1−5, confirms the presence of potentially reactive trimethylsilylchalcogenolate moieties and distorted tetrahedral geometry around the metal centers in each of these complexes. These compounds could potentially be utilized as a convenient source of paramagnetic ions into a semiconductor matrix for the synthesis of ternary clusters.
The ternary clusters (N,N´-tmeda)6Zn14-xMnxS13Cl2 (7a-d) and (N,N´-tmeda)6Zn14-xMnxSe13Cl2 (8a-d) and the binary clusters (N,N´-tmeda)6Zn14E13Cl2 (E= S, 9a; Se, 9b) have been synthesized by reacting (N,N´-tmeda)Zn(ESiMe3)2 with Mn2+ and Zn2+ salts. Single crystal X-ray analysis of the complexes confirms the presence of the six ‘(N,N´-tmeda)ZnE2’ units as capping ligands that stabilize the clusters, and distorted tetrahedral geometry around the metal centers. Mn2+ is incorporated into the ZnE matrix by substitution of Zn2+ ions in the cluster core. Complexes 7a, 8a and 8d represent the first examples of ‘Mn/ZnE’ clusters with structural characterization and indications of the local chemical environment of the Mn2+ ions. DFT calculations indicate that replacement of Zn with Mn is perfectly feasible and at least partly allows for the identification of some sites preferred by the Mn2+ metals. These calculations, combined with luminescence studies suggest a distribution of the Mn2+ in the clusters. The room temperature emission spectra of clusters 7c-d display a significant red shift relative to the all zinc cluster 9a, with a peak maximum centered at 730 nm. Clusters 8c-d have a peak maximum at 640 nm in their emission spectra.
The chalcogenolate complexes 3a and 4 have been utilized as molecular precursors for the isolation of ternary nanoclusters, with approximate formulae [Mn35/36Ag118/116S94(PnPr3)30], 10 and [Mn19/20Ag150/148S94(PnPr3)30], 11 respectively. Mn2+ is incorporated into the Ag2S matrix by substitution of two Ag+ ions in the cluster core.
Khadka, Chhatra Bahadur, "Transition Metal Complexes with Reactive Trimethylsilylchalcogenolate Ligands: Precursors for the Preparation of Ternary Nanoclusters" (2011). Electronic Thesis and Dissertation Repository. 336.