Vanadocene

Vanadocene
Names

IUPAC name Bis(cyclopentadienyl)vanadium
Other names Vanadocene
Identifiers
CAS Number	1277-47-0^Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.149.756
PubChem CID	18667909
UNII	GZ5K54AP9L^Y
CompTox Dashboard (EPA)	DTXSID10925957
SMILES c1ccc[cH-]1.c2ccc[cH-]2.[V+2]
Properties
Chemical formula	V(C₅H₅)₂
Molar mass	181.128 g/mol
Appearance	Violet Crystal
Melting point	167 °C (333 °F; 440 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references

Chemical compound

Vanadocene, bis(η⁵-cyclopentadienyl) vanadium, is the organometallic compound with the formula V(C₅H₅)₂, commonly abbreviated Cp₂V. It is a violet crystalline, paramagnetic solid. Vanadocene has relatively limited practical use, but it has been extensively studied.

Structure and bonding

V(C₅H₅)₂ is a metallocene, a class of organometallic compounds that typically have a metal ion sandwiched between two cyclopentadienyl rings. In the solid state, the molecule has D_5d symmetry. The vanadium(II) center resides equidistant between the center of the two cyclopentadienyl rings at a crystallographic center of inversion. The average V-C bond distance is 226 pm.^[1] The Cp rings of vanadocene are dynamically disordered at temperatures above 170 K and are only fully ordered at 108 K.

Preparation

Vanadocene was first prepared in 1954 by Birmingham, Fischer, and Wilkinson via a reduction of vanadocene dichloride with aluminum hydride, after which vanadocene was sublimed in vacuum at 100 ˚C.^[2] A modern synthesis of vanadocene that allows production in higher quantities requires treating [V₂Cl₃(THF)₆]₂[Zn₂Cl₆] with cyclopentadienylsodium.^[3]

2 [V₂Cl₃(THF)₆]₂[Zn₂Cl₆] + 8 NaCp + THF → 4 Cp₂V

Properties

Vanadocene is a reactive molecule. As it only has 15 valence electrons available, it readily reacts with many ligands. With alkynes, for example, it reacts to yield the corresponding vanadium-cyclopropene complexes.^[4]

One reaction involves carbon monoxide, leading to an ionic vanadocene derivative when performed in inert atmosphere:

Cp₂V + V(CO)₆ → [Cp₂V(CO)₂][V(CO)₆]

Vanadocene is readily oxidized to the monocation when treated with a ferrocenium salt in toluene.^[5]

VCp₂ + [FeCp₂]BR₄ → [VCp₂]BR₄ + FeCp₂ (R = Ph or 4-C₆H₄F)

These monocations are extremely air-sensitive and have a redox potential of -1.10 V.^[5]

Vanadocene reacts with high pressures of carbon monoxide to give CpV(CO)₄.^[6]

References

^ Robin D. Rogers; Jerry L. Atwood; Don Foust & Marvin D. Rausch (1981). "Crystal Structure of Vanadocene". Journal of Crystal and Molecular Structure. 11 (5–6): 183–188. doi:10.1007/BF01210393. S2CID 93048446.
^ Birmingham, J. M., A. K. Fischer, and G. Wilkinson (1955). "The Reduction of Bis-cyclopentadienyl Compounds". Naturwissenschaften. 42 (4): 96. Bibcode:1955NW.....42Q..96B. doi:10.1007/BF00617242. S2CID 44523847.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Lorber, C. "Vanadium Organometallics." Chapter 5.01. Comprehensive Organometallic Chemistry III. Elsevier, 2007. 1-60.
^ Jordan, Markus (2009). Azine in der Koordinationssphäre von Vanadocenderivaten unterschiedlicher Oxidationsstufen (PhD thesis). Universität Oldenburg.
^ ^a ^b Calderazzo, Fausto, Isabella Ferri, Guido Pampaloni, and Ulli Englert (1999). "Oxidation Products of Vanadocene and of Its Permethylated Analogue, Including the Isolation and the Reactivity of the Unsolvated [VCp]Cation". Organometallics. 18 (13): 2452–2458. doi:10.1021/om9809320.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ King, R.B.; Stone, F.G.A. (1963). "Cyclopentadienyl Metal Carbonyls and Some Derivatives". Inorganic Syntheses. Vol. 7. pp. 99–115. doi:10.1002/9780470132388.ch31. ISBN 9780470132388. {{cite book}}: |journal= ignored (help)