|Abstract or Summary
- I. Lithium alkyl and aryl monosubstituted cyclooctatetraenide
dianions (Li₂ C₈H₇-R; R = methyl, n- butyl, sec- butyl, tert- butyl,
phenyl and benzyl) were synthesized by the reaction of the appropriate
organolithium reagent with cyclooctatetraene in diethyl ether or
tetrahydrofuran. The reaction occurred cleanly and with good yield
of lithium monosubstituted cyclooctatetraenide dianion at ambient or
lower temperature for all organolithium reagents studied except
tert-butyl-lithium. (TMEDA is needed as an activator for methyllithium.) Substituted cyclooctatetraenide dianions were characterized
by chemical reactions, i. e., oxidation, hydrolysis and deuterolysis,
as well as, preparation of organometallic derivatives, substituted
uranocenes. A two step mechanism for the reaction is proposed
which involves the addition of the organolithium reagent to cyclooctatetraene followed by proton removal to yield the appropriate
ten-Tr electron aromatic dianion.
Several other alkyl organometallic compounds failed to produce
mono substituted cyclooctatetraenide dianions on reacting with cyclooctatetraene.
Lithium hexaalkyluranate(IV) complexes reacted with
cyclooctatetraene to give uranocene in good yield along with high
yields of coupled alkyl products.
II. The addition of lithium cycloheptadienide (LiC₇H₈-R; R = hydrogen, methyl and n-butyl) to lanthanide and actinide chlorides
results in the facile formation of unstable cycloheptatrienyl trianionmetal
compounds. Characterization of the ten-π aromatic cycloheptatrienyl
trianion (C₇H₆-R⁻³) was made by identification of the organic
products resulting from chemical reactions of the coordinated ligand,
for example, hydrolysis, deuterolysis and oxidation, as well as,
spectroscopic characterization (¹H NMR) of paramagnetic uranium(IV)
compounds. Qualitative analysis of the paramagnetic ¹H NMR shifts
are discussed based on the assumption that metal-ligand bond distances
and magnetic properties in cycloheptatrienyl-uranium(IV) compounds
are similar to those of uranocene. Formation of the cycloheptatrienyl
trianion is believed to occur by the loss of two methylene
protons from the metal coordinated cycloheptadienide ion. The role
of the lanthanide and acinide metal ions in cycloheptatrienyl trianion
formation is discussed. III. Metal atom vapors of several d- and f-transition elements were cocondensed with cyclohexanone at -196°C. Radical reduction
of cyclohexanone to bicyclohexy1-1'diol, a pinacol, was observed for
elements which are both highly electropositive and form strong metal
oxygen bonds, for example, the early transition, lanthanide and actinide
elements. High yields of aldol condensation products were produced
along with a small amount of bicyclohexylidene. Metal atoms of the latter transition elements were much less reactive with cyclohexanone
and did not yield a pinacol product.
Titanium clusters were prepared by codepositing titanium atoms
with a large excess of solvent. Titanium clusters were less reactive
than titanium atoms toward cyclohexanone radical reduction reactions.
High surface area titanium powders produced by solution techniques,
yield pinacols when cyclohexanone reacts in excess and further
deoxygenate pinacolic dianions to olefins under conditions of limited
Nitrobenzene was deoxygenatively coupled to azoxybenzene and
azobenzene by lanthanide and actinide metal atoms.