title: Syntheses and structures of sterically congested linear and branched cobalta[n]triangulanes.
abstract: Treatment of {eta(5):eta(1)[2-(di-tert-butylphosphanyl-P)ethyl]cyclopentadienyl}cobalt(I) chloride (5) with methylenecyclopropane (3) or bicyclopropylidene (4), as well as with their spirocyclopropanated analogues methylenespiropentane (7), cyclopropylidenespiropentane (10), or 7,7'-bi(dispiro[2.0.2.1]heptylidene) (15) in the presence of sodium amalgam at -50 degrees C, furnished the stable cobalt complexes 6, 9, 8, 11, and 16, respectively, in 72, 83, 84, 86, and 54 % isolated yield, respectively. The complexes 14 and 16 were also obtained by ligand exchange of the ethene complex {eta(5):eta(1)[2-(di-tert-butylphosphanyl-P)ethyl]cyclopentadienyl}(eta(2)-ethene)cobalt(I) (12) with 13 and 15 in 79 and 52 % yield, respectively. The X-ray crystal-structure analyses of complexes 9, 14, and 16, as well as the NMR-spectroscopic data of all complexes, reveal that they can be regarded as linear and branched cobalta[n]triangulanes. The thermal stability of complexes 6, 8, and 9 up to 109, 145, and 160 degrees C was determined by differential thermal analysis-thermogravimetry (DTA-TG) analysis.
authors.affiliation: Institut für Organische und Biomolekulare Chemie der Georg-August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany. Armin.deMeijere@chemie.uni-goettingen.de
authors.forename: Sergei I
authors.initials: SI
authors.lastname: Kozhushkov
authors.forename: Jan
authors.initials: J
authors.lastname: Foerstner
authors.forename: Alf
authors.initials: A
authors.lastname: Kakoschke
authors.forename: Dirk
authors.initials: D
authors.lastname: Stellfeldt
authors.forename: Li
authors.initials: L
authors.lastname: Yong
authors.forename: Rudolf
authors.initials: R
authors.lastname: Wartchow
authors.forename: Armin
authors.initials: A
authors.lastname: de Meijere
authors.forename: Holger
authors.initials: H
authors.lastname: Butenschön