Abstract
Methyldiphenylphosphonium cyclopentadienylide, C5H4PMePh2 (II), has been
synthesized and characterized spectroscopically and
crystallographically, and has been found to exhibit properties
consistent with the zwitterionic structure IIb. New group 6
complexes, (η5-C5H4PMePh2)M(CO)3, have been synthesized
and fully characterized. Comparisons of ν(CO) of these complexes with those of the
isoelectronic (η6-C6H6)M(CO)3 and [(η5-C5H5)M(CO)3]- suggest that the electron
donating ability of the ylide is between that of the cyclopentadienyl anion (Cp-) and
benzene, but closer to Cp-. The electronic structures of II and of (η5-
C5H4PMePh2)Cr(CO)3 have been investigated using ab initio methodologies. Thermal
and photochemical substitutions of the CO ligands of (η5-C5H4PMePh2)M(CO)3 (M = Cr,
Mo) by equimolar amounts of PMe3 and PPh3 were not observed, but the ylide is
displaced photochemically from (η5-C5H4PMePh2)Mo(CO)3 by excess PMe3 to form fac-
Mo(CO)3(PMe3)3 while (η5-C5H4PMePh2)Mo(CO)3 reacts with I2 to form [(η5-
C5H4PMePh2)Mo(CO)3I]I.
One electron oxidations of (η5-C5H4PMePh2)M(CO)3 (M = Cr, Mo, W) have been
performed to give the cationic radicals [(η5-C5H4PMePh2)M(CO)3]+, which undergo
dimerization to give dicationic metal-metal bonded dimers ((η5-C5H4PMePh2)M(CO)3)2
2+
in the solid state. These complexes have been fully characterized spectroscopically and
crystallographically. It has been determined that the chromium dimer ((η5-
C5H4PMePh2)Cr(CO)3)2
2+ undergoes dissociation extensively in solution to the persistent
radical cation monomer (η5-C5H4PMePh2)Cr(CO)3
+, but that the heavier metal analogues
iii
((η5-C5H4PMePh2)M(CO)3)2
2+ (M = Mo, W) dissociate very little, if at all. The Cr-Cr
bond distance of the chromium complex is 3.3509(7) Å, which is the longest Cr-Cr bond
distance known for a compound not containing some type of ligand bridging the metalmetal
bond.
The hitherto unknown indenyl-derived ylide, C9H6PMePh2, has been synthesized
and characterized spectroscopically and crystallographically. The chromium tricarbonyl
complex of this ligand, (η5-C9H6PMePh2)Cr(CO)3, has been synthesized and
characterized spectroscopically and crystallographically. This complex is a mixture of
two isomers exhibiting planar chirality generated upon coordination of the ligand. This
complex represents the first structurally characterized phosphorus noncyclopentadienylide
coordinated in an η5 manner. The spectroscopic and crystallographic
behaviour of C9H6PMePh2 demonstrates that this ylide behaves much like the related
cyclopentadienylides. / Thesis (Ph.D, Chemistry) -- Queen's University, 2007-09-07 11:46:39.391
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/661 |
| Date | 12 September 2007 |
| Creators | Brownie, John Hugh |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | 2795003 bytes, application/pdf |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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