Vanadocene
- Bis ( η5 -cyclopentadienyl ) vanadium
- Di (cyclopentadienyl ) vanadium
- (Cp) 2 V
Purple solid
Fixed
167 ° C.
Decomposes in water
Risk
Template: Infobox chemical / molecular formula search available
Vanadocene, or di ( cyclopentadienyl) vanadium, abbreviated Cp2V, is an organometallic compound selected from the family of metallocenes. It forms a sandwich complex ferrocene analog, but does not follow the 18- electron rule, since it has only 15 valence electrons.
Representation
Vanadocene of Birmingham, Fischer and Wilkinson 1954 was first prepared by reduction of vanadocene dichloride with aluminum hydride. The vanadocene was then sublimed at 100 ° C.
, 1977 Kohler et al. preparing vanadocene by the reaction of the vanadium complex [ V2Cl3 (THF ) 6] 2 [ Zn2Cl6 ] with cyclopentadienylsodium:
If vanadium (III ) chloride reacted directly with cyclopentadienylsodium, the latter acts as a reducing agent, and it is a by- product by the coupling of two Cp remains the Dihydrofulvalen:
Properties
Vanadocene is a purple, crystalline, paramagnetic solid. In the solid state the molecules D5d have symmetry. The vanadium ( II) center is located in the center of symmetry equidistant between the two cyclopentadienyl rings. The average V -C bond length is 226 pm. The cyclopentadienyl rings in vanadocene are disturbed dynamically at a temperature above 170 K and completely ordered only below 108 K. The dissociation of the Cp V binding, depending on the literature, indicated by 145 kJ · mol -1 and 369 kJ · mol -1.
Reactions
The vanadocene is a reactive molecule. It can be easily oxidized by reaction with a ferrocenium salt in toluene the monocation:
Since vanadocene has only 15 Valenzelektroen, it reacts readily with other ligands. With acetylene vanadocene reacts to Vanadiumcyclopropenkomplexen:
The reductive ring exchange with butyl lithium in the presence of 1,3-cyclohexadiene can be a cyclopentadienyl ring of Vanadocens replaced by a benzene ring: