H. Schottenberger et al., MIXED-MEMBERED-BISFULVALENE DIMETAL-COMPLEXES VIA METALLOCENE-SUBSTITUTED NORBORNENYL ALCOHOLS, Journal of organometallic chemistry, 541(1-2), 1997, pp. 249-260
A proven synthetic method for mixed-metal [0.0] bimetallocenophanes co
ntaining Fe, Ru and Co is presented in detail. Utilising norbonenyl al
cohol precursors, doubly lithiated ruthenocene or ferrocene were react
ed with bicyclo[2.2.1]-hept-2-en-7-one (norborn-2-en-7-one) to yield a
mixture of stereoisomeric alcohols, or respectively spiro-ethers, whi
ch can be separated by means of chromatography. The initially formed a
lcoholates were further reacted with diethylchlorophosphate to yield t
he respective chloro-substituted derivatives. Subsequent reductive cle
avage of the chlorine-carbon bonds by lithium-powder in DME afforded t
he metallocene-substituted norbornenyl carbanions, which eliminated et
hylene at ambient temperature to form dilithium metallocenylenebis(cyc
lopentadienylides) In a final step, reaction with cobalt dichloride pr
oduced the mixed-metal bimetallocenophanes 1,1'-(1,1'-cobaltocenediyl)
-ferrocene and 1,1'-(1,1'-cobaltocenediyl)-ruthenocene respectively. T
arget-compounds isolated as monocationic hexafluorophosphate salts as
well as isolable intermediate products were characterized mainly by NM
R-, LR-and MS-techniques. The X-ray structures of 1,1'-(1,1'-cobaltoce
niumdiyl)-ruthenocene PF6- and selected norbornenols are presented. an
ti-, anti-Bisnorbornenol Ib exhibits significant sandwich plane distor
tions induced by hydrogen bridges. The dimers formed in the solid stat
e resemble covalent ansa-type conformations. Furthermore, the syntheti
c route of reacting mono-and dilithiometallocenes with norbornenone wa
s applied to the lithium and dilithium acetylides of ethynyl and 1,1'-
diethynylferrocene. The attempted extension of the described synthetic
concept to mono-and dinorbornenol-substituted ferrocenylethynes for t
he final conversion to ferrocene-1,1'-bis(ethynylcyclopentadienides) d
id not allow the preparation of the desired ethyne-spacered bimetalloc
enophane species. (C) 1997 Elsevier Science S.A.