Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor

Prof. Dr. J. F. Corrigan

Abstract

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)44-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)43-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 15, 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.


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