| Summary: | Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999. === Vita. === Includes bibliographical references. === The synthesis and structure of several Zr(IV) carboxylate complexes are described in which the bridging carboxylate is the dianion of 111-xylylenediamine bis(Kemp's triacid imide) (H2XDK) or the more soluble propyl derivative (H2PXDK). Reaction of either H2XDK or H2PXDK with [Zr(CH2Ph)4] or [Zr(NMe2)4] afforded [Zr(CH2Ph)2(XDK)] or [Zr(NMe2)2(XDK)]. [Zr(CH2Ph)2(XDK)] is a rare example of an alkyl zirconium carboxylate complex. [Zr(CH2Ph)2(XDK)] reacts with various pyridine derivatives to yield the 7-coordinate pyridine adduct. An aryl isocyanide (2 equiv) reacts with [Zr(CH2Ph)2(XDK)] to afford the iminoacyl complex [Zr{11 2 -2,6- Me2PhNCCH2Ph}2(XDK)]. [Zr(CH2Ph)2(XDK)] is unreactive, however, towards weak sigma donors such as CO. The eight-coordinate complex [Zr(XDK)2] was formed by either treating [Zr(NMe2)4] with H2XDK (2 equiv) or [Zr(CH2Ph)2(XDK)] with H2XDK. Several of these complexes have been characterized by X-ray crystallography. [Zr(CH2Ph)2(XDK)] is electrophilic since the ipso carbon of one benzyl group is interacting with the Zr center as revealed by the acute Zr-C-C(ipso) angle in the X-ray structure of [Zr(CH2Ph)2(XDK)]. These studies have shown that 6-coordinate Zr carboxylate complexes are electrophilic. Complexes of this type are most stable when they possess high coordination numbers; this trend is exemplified by the stability of [Zr(XDK)2] and [Zr(eta)rt2-2,6-Me2PhNCCH2Phh(XDK)]. === by Dietrich P. Steinhubel. === Ph.D.
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