Intramolecular electronic communication between dimetal units with multiple metal-metal bonds /
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| Other Authors: | , |
| Format: | Thesis eBook |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University],
[2010]
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| Subjects: | |
| Online Access: | Link to OAK Trust copy |
| Abstract: | Intramolecular electron transfer between a donor and an acceptor group is a fundamental process with considerable implications in chemistry, biology, physics and molecular electronics. In this work, quadruply bonded dimolybdenum units have been employed to build supramolecules, including dimer of dimers and tetranuclear clusters. Electronic communication between the dimetal units has been investigated both experimentally and theoretically. Dimer of dimers, described by a general formula [Mo₂]L[Mo₂], where [Mo₂] = [Mo₂(DAniF)₃]⁺ and DAniF = N,N'-di-p-anisylformamidinate, have been synthesized and these compounds can be chemically oxidized in a controllable way. The molecular structures and electronic properties of these complexes have been modified by changes in the bridging ligands. In this work, diamidates, fluoflavinate and dithioxamidates have been utilized as bridging ligands, L. It was found that, generally, the electronic coupling between the metal centers increases as substitution of O-donor atoms to N or S in the linkers, if the substution does not change the structure substantially. Density Functional Theory calculations on model compounds show that metal to ligand back bonding is critical to the electron transfer pathway. Tetranuclear Mo₄ clusters with two [Mo₂(cis-DAniF)₂]²⁺ units linked by single atoms usually show large electronic communication, attributed to the short separation between dimetal units and possible direct [delta] to [delta] orbital interactions. In this dissertation the shortest distance between the dimetal centers, ca. 3.25 Å, were found for the compounds linked by alkoxides, [Mo₂(cis-DAniF)₂]₂([mu]-OR)₄, R = Me or Et. The separation between the dimetal units decreases as [Mo₂(cis-DAniF)₂]₂([mu]-OCH₃)₄ is singly and then doubly oxidized, which suggests bond formation between dimetal centers. The analogous tetranuclear compounds linked by bidentate bridges, [Mo₂]₂([mu]-X-X)₂ (X = O or S), have also been obtained. [Mo₂(cis-DAniF)₂]₂([mu]-o-S₂C₆H₄)₂ shows an exceptionally strong electronic coupling due to super-exchange pathway, even though the Mo₂···Mo₂ distance of 3.724 Å is considerably larger than 3.267 Å for the corresponding O bridged compound. |
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| Item Description: | "Major Subject: Chemistry" Title from author supplied metadata (automated record created 2010-03-12 12:08:51). Electronic resource. |
| Physical Description: | 1 online resource. |
| Bibliography: | Includes bibliographical references. |