1,1'-(Tetramethylethylene)-Ferrocene. Obliquity and N.M.R. In Bridged Ferrocenes

Relaxed but Highly Compact Diansa Metallacyclophanes

“…In rotamer a (in this part of disordered [7] -anions show reasonable geometrical parameters) the Co3 ••• P1a distance is 2.769(1) Å , which is longer than the covalent radii of Co and P (231 pm) but much shorter than the sum of van der Waals radii's of the atoms (380 pm). The cage bridging distances, C1−P1a and C1'−P1a are 1.863 (4) and 1.915(4), respectively. The bridging angle, C1−P1a−C1' is 92.6(2)°, is distorted from ideal tetrahedral angle (109.5) ° due to the bond to the rigid boron cages.…”

“…On the other hand, for oxidized anions [4] -, [5] -and [6] -there is no interaction between phosphorus and cobalt due to the absence of the P lone pair, which is bonded to the chalcogen atoms ( Figure 12). The interactions found in these compounds are between the P-C c bonds and the empty 4s orbital of cobalt with a similar energy of ca.…”

“…Finally, in order to prove the existence of a direct interaction between the Co and the P, an AIM (atoms in molecules) analysis on anions [3] -and [4] -was performed. 33 A critical point (3, +1) was identified between the Co and the P atoms in both anions indicating the centre of a ring rather than the existence of a direct interaction.…”

“…The most compact to date confronted ferrocenophane is Me 4 C 2 fcS 3 that can also be written as Me 4 C 2 [2]S 3 [3]ferrocenephane 7 to indicate the length of the two different ansas. 4 Cobaltabisdicarbollide, [3,3'- interactions between the P atom bridge and its available lone pair from an ansa and the metal of the metallacyclophane modulated by a confronting second ansa. It was expected that this confronting two ansa system could tune the structural, electronic and electrochemical properties of the complex.…”

Versuche zur Synthese von [2.2]- und [2.3]Cyclopentadienophanen

“…Dagegen blieben Cyclopentadienophane des Typs 1 bis heute unbekannt, welche nach Schema 1 (oben) zur Synthese von Polyferrocenophanen 2 prädestiniert wären. Dies ist um so überra-schender, als Rinehart et al [8] schon 1960 durch reduktive Behandlung von 6,6-Dimethylfulven (3) im Na-Kontakt und Rekombination der dabei gebildeten RadikalAnionen (4 3 5) einen einfachen Weg zur Einführung einer C 2 -Brücke gefunden haben, welcher auch zur Knüpfung einer zweiten C 2 -Brücke dienen könnte. Zweifellos stellen Cyclopentadienophane 1 (ganz im Gegensatz zu Ferrocenophanen) hochreaktive Verbindungen mit zwei Dien-Strukturelementen dar, welche bei tiefer Temperatur synthetisiert und isoliert werden müssen, da sie sich bei Raumtemperatur durch intraoder intermolekulare Cycloadditionen dem Nachweis entziehen können.…”