Synthetic Investigations Featuring Amidometallic Complexes
Abstract
Chapters 1-3 describe results illustrating a new technique for synthesizing nanoclusters of metal sulfide semiconductors within block copolymer microdomains. The sulfides of divalent Zn, Cd, and Pb were considered. Block copolymers were prepared using living ring-opening metathesis polymerization techniques based on well-defined initiators such as Mo(NAr)(CHR)(OR)_2 (Ar = 2,6-C_6H_3 -i-Pr_2; R = t-Bu). Certain amidometallic complexes were prepared that were polymerized in a living fashion permitting block copolymer synthesis; the block copolymers were converted to films through static casting and the domain-confined amidometallic complexes served as precursors to metal sulfides. In the course of this research a preparative route to light-sensitive pentamethylcyclopentadienyl cadmium complexes was uncovered. This led in turn to a nanocluster synthesis in which a precursor complex such as ZnPh_2 or CdAr_2 (Ar = 3,5-C_6H_3 (CF_3)_2) was attached to the desired block copolymer by a dative link. It was possible to synthesize ZnS and CdS within block copolymers displaying various morphologies using this versatile methodology. Chapters 4-9 describe transition metal chemistry stemming from the application of a novel tetradentate, tris(amido) ligand system: (RNCH_2CH _2)_3N (R = Me_3 Si, (N_3N); R = t-BuMe _2Si, (N_3N ^'); R = Et_3Si, (N_3N^*]). A terminal monohydride complex, HTi (N _3N), was investigated with respect to cyclometallation and ethylene insertion chemistry. A series of trigonal monopyramidal complexes M (N_3N) ^') (M = Ti, V, Cr, Mn, and Fe) was synthesized; the rare TMP coordination geometry has not previously been encountered for early transition metal complexes. The chemistry of V (N_3 N) was studied extensively; chalcogenide atom and imido group transfer to V (N_3N) are facile processes that lead to a formal two-electron oxidation of vanadium and give rise to a terminal vanadium -element multiple bond. Starting from Fe (N_3 N^') it was possible to synthesize a diamagnetic iron (IV) cyanide complex, (NC)Fe (N_3N^' ]. Treatment of Cl_2 Ta (N_3N) with the appropriate phosphide gave rise to terminal phosphinidene complexes of the type RPTa (N_3N) (R = Ph, t-Bu, c-C_6H_{11 }). These react with carbonyl compounds, producing OTa (N_3N) along with the corresponding phosphaalkene. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.) (Abstract shortened by UMI.).
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1993
- Bibcode:
- 1993PhDT.......148C
- Keywords:
-
- SEMICONDUCTORS;
- BLOCK COPOLYMERS;
- METAL SULFIDES;
- Chemistry: Inorganic; Chemistry: Polymer; Engineering: Materials Science; Physics: Condensed Matter