Niobocene dichloride

Niobocene dichloride
IUPAC name dichloridobis (η5- cyclopentadienyl) niobium
Other names Niobocene dichloride
Identifiers
CAS number	12793-14-5
RTECS number	QU0400000
Properties
Molecular formula	C10H1oCl2Nb
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
R-phrases	36/37/38
S-phrases	26-36
Related compounds
Related compounds	Cp2TiCl2 Cp2MoCl2 Cp2VCl2
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.

It is prepared via a multistep reaction beginning with treatment of niobium pentachloride with cyclopentadienylsodium:^[1]

NbCl₅ + 6 NaC₅H₅ → 5 NaCl + (C₅H₅)₄Nb + organic products

(C₅H₅)₄Nb + 2 HCl + 0.5 O₂) → [{C₅H₅)₂NbCl}₂O]Cl₂ + 2 C₅H₆

2 HCl + [{(C₅H₅)₂NbCl}₂O]Cl₂ + SnCl₂ → 2 (C₅H₅)2NbCl₂ + SnCl₄ + H₂O

It was originally reported by Geoffrey Wilkinson.^[2] It was investigated as a potential anti-cancer agent.^[3]

References

1. ^ C. R. Lucas, J. A. Labinger, J. Schwartz (1990). Robert J. Angelici. ed. "Dichlorobis(η5-Cyclopentadienyl)Niobium(IV)". Inorg. Synth. (New York: J. Wiley & Sons) 28: 267–270. doi:10.1002/9780470132593.ch68. ISBN 0-471-52619-3. 
2. ^ G. Wilkinson and J.G. Birmingham (1954). "Bis-cyclopentadienyl Compounds of Ti, Zr, V, Nb and Ta". J. Am. Chem. Soc. 76 (17): 4281–4284. doi:10.1021/ja01646a008. 
3. ^ Mokdsi, G.; Harding, M. M. (2001). "A¹H 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.