Niobocene dichloride - Misplaced Pages

Niobocene dichloride
Names

IUPAC name Dichloridobis (η-cyclopentadienyl)niobium
Other names Niobocene dichloride
Identifiers
CAS Number	12793-14-5
3D model (JSmol)	Interactive image
ChemSpider	21251691
ECHA InfoCard	100.159.630
EC Number	631-385-9
PubChem CID	16211739
RTECS number	QU0400000
InChI InChI=1S/2C5H5.2ClH.Nb/c21-2-4-5-3-1;;;/h21-5H;2*1H;/q;;;;+2/p-2Key: CYMWZQTUXXEBCR-UHFFFAOYSA-L
SMILES 1cccc1.1cccc1.ClCl
Properties
Chemical formula	C₁₀H₁₀Cl₂Nb
Molar mass	294 g/mol
Appearance	brown solid
Melting point	dec.
Boiling point	dec.
Solubility in water	soluble (hydrolysis)
Solubility in other solvents	sparingly in chlorocarbons
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Related compounds
Related compounds	Cp₂TiCl₂ Cp₂MoCl₂ Cp₂VCl₂
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is ?) Infobox references

Chemical compound

Niobocene dichloride is the organometallic compound with the formula (C₅H₅)₂NbCl₂, abbreviated Cp₂NbCl₂. This paramagnetic brown solid is a starting reagent for the synthesis of other organoniobium compounds. The compound adopts a pseudotetrahedral structure with two cyclopentadienyl and two chloride substituents attached to the metal. A variety of similar compounds are known, including Cp₂TiCl₂.

Preparation and structure

It was originally reported by Geoffrey Wilkinson. It is prepared via a multistep reaction beginning with treatment of niobium pentachloride with cyclopentadienylsodium:

NbCl₅ + 5 NaC₅H₅ → 5 NaCl + (C₅H₅)₄Nb + "C₅H₅"

2 (C₅H₅)₄Nb + 4 HCl + 0.5 O₂ → [(C₅H₅)₂NbCl]₂OCl₂ + 4 C₅H₆

[(C₅H₅)₂NbCl]₂OCl₂ + SnCl₂ + 2 HCl → 2 (C₅H₅)₂NbCl₂ + SnCl₄ + H₂O

The compound adopts a "clamshell" structure characteristic of a bent metallocene where the Cp rings are not parallel, the average Cp(centroid)-M-Cp angle being about 130.3°. The Cl-Nb-Cl angle of 85.6° is narrower than in zirconocene dichloride (97.1°) but wider than in molybdocene dichloride (82°). This trend is consistent with the orientation of the HOMO in this class of complex.

Applications and further work

Unlike the related zirconacene and titanocene dichlorides, no applications have been found for this compound, although it has been studied widely. It was investigated as a potential anti-cancer agent.

References

"Bis(cyclopentadienyl)niobium(IV) dichloride". pubchem.ncbi.nlm.nih.gov. Retrieved 14 December 2021.
Wilkinson, G.; Birmingham, J. G. (1954). "Bis-cyclopentadienyl Compounds of Ti, Zr, V, Nb and Ta". J. Am. Chem. Soc. 76 (17): 4281–4284. doi:10.1021/ja01646a008.
C. R. Lucas (2007). "Dichlorobis(η -Cyclopentadienyl) Niobium(IV)". Inorganic Syntheses. Vol. 28. pp. 267–270. doi:10.1002/9780470132593.ch68. ISBN 978-0-471-52619-3. {{cite book}}: |journal= ignored (help)
K. Prout, T. S. Cameron, R. A. Forder, and in parts S. R. Critchley, B. Denton and G. V. Rees "The crystal and molecular structures of bent bis-π-cyclopentadienyl-metal complexes: (a) bis-π-cyclopentadienyldibromorhenium(V) tetrafluoroborate, (b) bis-π-cyclopentadienyldichloromolybdenum(IV), (c) bis-π-cyclopentadienylhydroxomethylaminomolybdenum(IV) hexafluorophosphate, (d) bis-π-cyclopentadienylethylchloromolybdenum(IV), (e) bis-π-cyclopentadienyldichloroniobium(IV), (f) bis-π-cyclopentadienyldichloromolybdenum(V) tetrafluoroborate, (g) μ-oxo-bis tetrafluoroborate, (h) bis-π-cyclopentadienyldichlorozirconium" Acta Crystallogr. 1974, volume B30, pp. 2290–2304. doi:10.1107/S0567740874007011
Mokdsi, G.; Harding, M. M. (2001). "AH NMR study of the Interaction of Antitumor Metallocenes with Glutathione". J. Inorg. Biochem. 86 (2–3): 611–616. doi:10.1016/S0162-0134(01)00221-5. PMID 11566334.