SmI2(THF)5 acted as a reducing agent in the reaction with phenylenebis(3,5-But4salicylidene)iminato sodium, (3,5-But4salophen)Na2(THF) 2, to yield a dimeric compound [Sm2(SB-SB)(THF)3] ·2toluene (2.2) [SB-SB = C-C bonded (3,5-Bu t4salophen dimer] arising from the reductive C-C coupling of two imine functional groups of two (3,5-But4salophen)Sm units. Complex 2.2 reacts with MeLi resulting in a novel oxo-bridged dimer, {[(Me2-SB)Sm(mu-CH3)Li(THF)][(Me2-SB)Sm(mu-CH 3)Li(THF)2Li(TBT)2]}(mu-O)(mu-Li)3 (2.3) [Me2SB = phenylenebis (3,5-But 4salicyl)dimethyldiamidato], featuring alkylation of both Sm atoms and arising from cleavage of the C-C bond connecting the two units, as well as complete reduction of the imine groups of the two salophen ligands and TBF deoxygenation. Similar cleavage of the connecting C-C bond of complex 2.2 was also observed during the reaction with dry O2 to form a distorted cuboid cluster in which four Sm atoms are bridged by four hydroxyl groups [(3,5-But4salophen)Sm (OH)] 4·4toluene (2.4). The nature of the substituents present on the calix-tetrapyrrole tetra-anion ligand {[R2C(C4H2N)]4} 4- [R = 1/2-(CH2)5- (a), Et (b)] determines the type of reactivity of the corresponding Sm(II) compounds with acetylene. Where R = 1/2-(CH2)5- dehydrogenation occurred to yield the nearly colorless dinuclear diacetylide complex. Conversely, where R = Et, acetylene coupling in addition to dehydrogenation resulted in the formation of a dimeric butatrienediyl enolate derivative. Reaction of the trivalent hydride or of the terminally bonded methyl derivative with acetylene resulted in a mixture of the carbide and the dimerization product 5.2b. The same reaction also yielded a third product, a trivalent complex in which the macrocycle was isomerized by shifting the ring attachment of one of the four pyrrole rings. Reaction of the mononuclear and trivalent (6.1a), ( 6.1b) with lithium under Ar in THF afforded the mononuclear divalent 6.3a where the enolate was formed by a THF cleavage process. In the case of direct reaction of SmI2(THF)5 with the tetralithiated form of the Rn-calix-pyrrole ligand, the two isomorphous enolates (6.3a and 6.3b) were the only isolated products. Complexes 6.3 react reversibly with ethylene to afford the corresponding light-green dinuclear ethylene adducts. The nature of the substituents; present on a dipyrrolide dianion ligand determines the assembly of Sm(II) clusters which participate to various extents in dinitrogen fixation and THF cleavage. Reaction of SMI2(THF) 2 with the methylphenyl dipyrromethanyl dianion resulted in the pentameric cluster 10.1 which exhibited no reactivity with dinitrogen. Conversely, reaction of SmI2(THF)2 with the cyclohexyl dipyrromethanyl dianion resulted in TBF cleavage to yield the tetranuclear oxo-bridged complex 10.2. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/8652 |
| Date | January 2000 |
| Creators | Dubé, Tiffany. |
| Contributors | Gambarotta, Sandro, |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 204 p. |
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