A structural investigation of the interaction between Lewis bases and Tetrakis (trifluoroacetato) dimolybdenum (II).
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1982.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to ProQuest Copy |
| Abstract: | Tetrakis(trifluoroacetato)dimolybdenum(II) was found to interact with Lewis bases in a variety of ways depending upon the strength and steric size of the Lewis base. Examples were found of both strong and weak coordination in the axial position and also the novel equatorially bound complexes. Seven complexes of the type Mo(,2)(O(,2)CCF(,3))(,4)L(,2) were prepared and structurally characterized. The ethyldiphenylphosphine, ether, and acetonitrile diadducts can all be prepared straightforwardly by reacting Mo(,2)(O(,2)CCF(,3))(,4) with the donor ligand in a non-coordinating solvent such as benzene or toluene. These complexes are all examples of weak coordination of the dinuclear unit with the donor molecule in the axial position. The Mo-L distances are 3.086(1)(ANGSTROM), 2.575(4)(ANGSTROM), and 2.605(4)(ANGSTROM), respectively. This coordination of the dinuclear unit has a small but real effect on the Mo-Mo bond length with the Mo-Mo bond distances being 2.128(1)(ANGSTROM), 2.113(1)(ANGSTROM), and 2.114(1)(ANGSTROM) as compared to the 2.090(4)(ANGSTROM) reported for the parent compound, where the intermolecular Mo --- O distances are 2.72(1)(ANGSTROM). The dimethylsulfoxide and methyldiphenylphosphine oxide complexes are examples of strong coordination of the dinuclear unit. The dimethylsulfoxide diadduct was prepared by the above method, while the methyldiphenylphosphine oxide diadduct was prepared serendipitously. Both complexes are remarkable in that they have very short Mo-L distances of 2.42(2)(ANGSTROM), and 2.396(3)(ANGSTROM). These are the first examples of strong coordination by a Lewis base to a dimolybdenum-tetracarboxylate unit. This stronger coordination has a corresponding greater effect upon the Mo-Mo bond distance with these distances being 2.125(1)(ANGSTROM), and 2.124(1)(ANGSTROM). These distances are within experimental error of the pyridine diadduct which has the longest Mo-Mo distance in the trifluoroacetate diadduct series of complexes, viz., 2.129(2)(ANGSTROM). The phenyldiethylphosphine and methyldiphenylphosphine diadducts are complexes with characteristics heretofore unobserved in quadruple bond chemistry. The phosphine ligands are bound equatorially to the dimer at coordination sites vacated by arms of the trifluoroacetate groups, two trifluoroacetate groups becoming monodentate. The Mo-Mo bond distances of 2.100(1)(ANGSTROM), and 2.107(2)(ANGSTROM) are not significantly changed from that in the parent compound. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | x, 103 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 97-102). |