Hafnocene dichloride

Hafnocene dichloride
Names
	Other names bis(cyclopentadienyl)hafnium dichloride
Identifiers
CAS Number	12116-66-4;
3D model (JSmol)	Interactive image;
ChemSpider	10654717;
ECHA InfoCard	100.031.967
EC Number	235-177-5;
PubChem CID	24942143;
	InChI InChI=1S/2C5H5.2ClH.Hf/c21-2-4-5-3-1;;;/h21-3H,4H2;21H;/q2-1;;;+4/p-2 Key: IXKLRFLZVHXNCF-UHFFFAOYSA-L;
	SMILES C1C=CC=[C-]1.C1C=CC=[C-]1.[Cl-].[Cl-].[Hf+4];
Properties
Chemical formula	C10H10Cl2Hf
Molar mass	379.58 g·mol−1
Appearance	white solid
Melting point	230–233 °C (446–451 °F; 503–506 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H315, H319, H335
Precautionary statements	P260, P261, P264, P264+P265, P271, P280, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P351+P338, P305+P354+P338, P316, P319, P321, P332+P317, P337+P317, P362+P364, P363, P403+P233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Hafnocene dichloride is the organohafnium compound with the formula (C₅H₅)₂HfCl₂. It is a white solid that is sparingly soluble in some organic solvents. The lighter homologues zirconacene dichloride and titanocene dichloride have received much more attention. While hafnocene is only of academic interest, some more soluble derivatives are precatalysts for olefin polymerization. Moreso than the Zr analogue, this compound is highly resistant to reduction.

It is prepared by a salt metathesis reaction from hafnium tetrachloride by salt metathesis:

2 NaC₅H₅ + HfCl₄ → (C₅H₅)₂HfCl₂ + 2 NaCl

Derivatives

Hydrolysis gives the trimer [(C₅H₅)₂HfO]₃.^[2]

The chloride ligands can be replaced by other halides.^[3]

The bis(phosphide) (C₅H₅)₂Hf(PR₂)₂ can be prepared by salt metathesis from hafnocene dichloride.^[4]

References

^ "Hafnocene dichloride". pubchem.ncbi.nlm.nih.gov.
^ Rogers, Robin D.; Vann Bynum, R.; Atwood, Jerry L. (1982). "Synthesis and Crystal Structure of [(η⁵-C₅H₅)₂HfO]₃C₆H₅Me". Journal of Crystallographic and Spectroscopic Research. 12 (3): 239–244. doi:10.1007/BF01195715. S2CID 97164127.
^ Druce, P. M.; Kingston, B. M.; Lappert, M. F.; Spalding, T. R.; Srivastava, R. C. (1969). "Metallocene Halides. Part I. Synthesis, Spectra, and Redistribution Equilibria of di-π-Cyclopentadienyldihalogeno-Titanium(IV),-Zirconium-(IV), and -Hafnium(IV)". J. Chem. Soc. A: 2106–2110. doi:10.1039/J19690002106.
^ Baker, R. T.; Whitney, J. F.; Wreford, S. S. (1983). "Characterization and Interconversion of Metal-Phosphorus Single and Double bonds: Bis(cyclopentadienyl)zirconium and -Hafnium Bis(diorganophosphide) Complexes". Organometallics. 2 (8): 1049–1051. doi:10.1021/om50002a022.

[1] "Hafnocene dichloride". pubchem.ncbi.nlm.nih.gov.

[2] Rogers, Robin D.; Vann Bynum, R.; Atwood, Jerry L. (1982). "Synthesis and Crystal Structure of [(η⁵-C₅H₅)₂HfO]₃C₆H₅Me". Journal of Crystallographic and Spectroscopic Research. 12 (3): 239–244. doi:10.1007/BF01195715. S2CID 97164127.

[3] Druce, P. M.; Kingston, B. M.; Lappert, M. F.; Spalding, T. R.; Srivastava, R. C. (1969). "Metallocene Halides. Part I. Synthesis, Spectra, and Redistribution Equilibria of di-π-Cyclopentadienyldihalogeno-Titanium(IV),-Zirconium-(IV), and -Hafnium(IV)". J. Chem. Soc. A: 2106–2110. doi:10.1039/J19690002106.

[4] Baker, R. T.; Whitney, J. F.; Wreford, S. S. (1983). "Characterization and Interconversion of Metal-Phosphorus Single and Double bonds: Bis(cyclopentadienyl)zirconium and -Hafnium Bis(diorganophosphide) Complexes". Organometallics. 2 (8): 1049–1051. doi:10.1021/om50002a022.

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