Luke Grocholl

Date of Award

9-26-2000

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Lothar Stahl

Abstract

Synthesis and single crystal X-ray studies of the bis(amido)cyclodisilazane [(tBuNSiMe)2(tBuNH)2] (24) and its lithium, zirconium, hafnium, and tin(IV) compounds are described. The pristine molecule is formed as both cis (24b) and trans (24a) isomers. Due to its large bite angle and sterically shielding structure, surprisingly stable metal and metalloid complexes can be formed with the cis isomer. Disorder problems prevent a satisfactory refinement of the cis-isomer's structure, but a single-crystal X-ray study of the trans-isomer (24a) is presented. The interaction of 24b with nBuLi in refluxing THF yielded the heterocubic [(tBuNSiMe)2( tBuNLi·THF)2] (25). The interaction of 25 with ZrCl4 or HfCl4 in hot toluene resulted in the corresponding metal complexes [(tBuNSiMe) 2(tBuN)2]ZrCl2 (26) and [(tBuNSiMe)2(tBuN)2]HfCl 2 (27). The 14-electron metal centers of these complexes are pseudo-tetrahedral and potential olefin polymerization catalysts. Since dialkyl species are important precursors for active polyolefin catalysts, the dimethyl derivatives of the zirconium and hafnium compounds were also synthesized. The treatment of 24b with SnCl2 in toluene/THF affords the tin(II) complex [(tBuNSiMe)2( tBuN)2Sn] (30), which is used as a building block for tin chalcogenides. The interaction of 30 with sulfur or selenium yields the tin(IV) dimers [(tBuNSiMe)2( tBuN)2SnS]2 (31) and [( tBuNSiMe)2(tBuN)2SnSe]2 (32). The bis(amido)cyclodiphosphazane cis-[(tBuNP) 2(tBuNH)2] 33 is isostructural with 24b. The dilithio salt [(tBuNP)2( tBuNLi·THF)2] (34) is synthesized in an analogous manner to 25 and reacts with ZrCl4 and HfCl4 in a similar manner. The resulting zirconium and hafnium complexes, [(tBuNP)2(tBuN)2 ]ZrCl2 (35) and [(tBuNP) 2(tBuN)2]HfCl2 (36) are also potential olefin polymerization catalysts. The bis(amido) ligand 33 forms a variety of different structures with metals and metalloids. When 34 is treated with AsCl 3, TlCl, or InCl the resulting compounds [(tBuNP) 2(tBuN)2]AsCl (39), [( tBuNP)2(tBuNP)2] (38), and [(tBuNP)2(tBuN)2In] 2 (37) are isolated as heterocubane, seco-cubane, and a dimer, respectively. Single crystal X-ray studies of all new compounds are presented.

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