Date of Award

1986

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

Three new types of lanthanide (Ln) complexes, namely, the first examples of homodinuclear macrocyclic lanthanide complexes, novel binary and ternary gaseous polyatomic lanthanide oxides and new lanthanide oxalato complexes are described in chapters one, two and three respectively. The homodinuclear complexes are 2:2 condensation products of 2,6-diformyl-p-cresol and triethylenetetramine templated by Ln(NO(,3))(,3) and Ln(ClO(,4))(,3). The complexes are dimorphic, and are off-white (the more stable form) when they are obtained from dilute solutions and orange if they arise from more concentrated reactants. The complexes were characterized by elemental analysis, fast atom bombardment mass spectrometry (FAB MS), electronic absorption and IR spectroscopy, thermogravimetry along with preliminary spectroscopic studies using electron paramagnetic resonance, magnetic susceptibility and luminescence. The orange complexes exhibit more antiferromagnetic exchange interactions, low Ln('3+) magnetic moments and multi-exponential luminescence decay kinetics, whereas the off-white complexes show single exponential luminescence decay and free ion magnetic moments. At low temperatures and in presence of excess triethylenetetramine, solvated light lanthanide mononuclear complexes of a 1:1 acyclic Schiff base acetal were isolated and the structure of one of these was confirmed by single crystal X-ray diffraction crystallography. FAB MS analysis of the homodinuclear or mononuclear lanthanide complexes led to the observation of novel binary gaseous polyatomic lanthanide oxide polynuclear species as unipositive ions: Ln(,2)O(,3), Ln(,3)O(,3), Ln(,3)O(,4), Ln(,4)O(,4), Ln(,4)O(,5), Ln(,4)O(,6), Ln(,5)O(,7), Ln(,6)O(,8), Ln(,6)O(,9), Ln(,7)O(,10), Ln(,8)O(,12), Ln(,9)O(,13) (Ln = La - Lu, Y). Sources for these oxides seem to be general, so that the oxides Ln(,3)O(,4) and smaller, are generated from simple salts and sesquioxides. The interesting ternary oxides LaYbO(,2), La(,2)YbO(,4), LaYb(,2)O(,4), CeEuO(,2), Ce(,2)EuO(,4), CeEu(,2)O(,3), NdHoO(,3), Nd(,2)HoO(,4), NdHo(,2)O(,4), TmYO(,3), Tm(,3-x)Y(,x)O(,4), Tm(,4-x)Y(,x)O(,6), Tm(,5-x)Y(,x)O(,7), Tm(,6-x)Y(,x)O(,9), x = 1-5, and GdGaO(,3) were observed in FAB MS analysis of appropriate mixtures of dinuclear complexes or nitrates. The new lanthanide oxalato complexes K(,3)Ln(C(,2)O(,4))(,3)(.)3H(,2)O and K(,8)Ln(,2)(C(,2)O(,4))(,7)(.)14H(,2)O were prepared; single crystal X-ray diffraction crystallography was used to establish their structures. Discussions of their crystal structures, the crystal chemistry of Ln('3+) cations in these and other compounds as well as thermal characteristics of K(,4)Ln(,2)(C(,2)O(,4))(,5)(.)nH(,2)O, K(,3)Ln(C(,2)O(,4))(,3)(.)3H(,2)O and K(,8)Ln(,2)(C(,2)O(,4))(,7)(.)14H(,2)O are presented.

Pages

210

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