Osmocene

Structural formula
Ecliptic conformation
General
Surname	Osmocene
other names	Bis (η 5 -cyclopentadienyl) osmium Di (cyclopentadienyl) osmium (Cp) 2 Os
Molecular formula	C 10 H 10 Os
Brief description	white, crystalline solid
External identifiers / databases
CAS number 1273-81-0 EC number 215-055-8 ECHA InfoCard 100.013.687 PubChem 79163 Wikidata Q424867
properties
Molar mass	320.42 g mol −1
Physical state	firmly
density	2.58 g cm −3
Melting point	226-228 ° C
solubility	soluble in diethyl ether
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 315-319-335 P: 261-305 + 351 + 338-302 + 352-321-405-501
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Osmocene , or also di (cyclopentadienyl) osmium, [Os (C ₅ H ₅ ) ₂ ], abbreviated [OsCp ₂ ], is an organometallic compound from the family of metallocenes . It is isoelectronic to ferrocene and ruthenocene and, like these, also forms a sandwich complex . In contrast to ferrocene and ruthenocene, which are well-studied compounds, far less is known about osmocene due to the price, low availability and toxicity of osmium.

Manufacturing

Osmocene was first synthesized by Ernst Otto Fischer and Heinrich Grumbert . It can u. a. by the reaction of osmium tetroxide with hydrogen bromide and subsequent reaction with zinc and cyclopentadiene .

${\displaystyle {\ce {OsO4->[{\text{1. HBr}}][{\text{2. Zn/C}}_{5}{\text{H}}_{6}][Os(C_{5}H_{5})_{2}]}}}$

properties

Osmocene is a white solid that is commercially available. Like the isoelectronic compounds ferrocene and ruthenocene from the same group, osmocene forms an eclipsed structure with an Os – C bond length of 222  pm . The distance between the rings is 371 pm. Compared to ferrocene and ruthenocene, osmocene is less reactive towards electrophilic aromatic substitution, but shows the greatest tendency to form adducts with Lewis acids . The osmocenium cation [OsCp ₂ ] ⁺ dimerizes to form an Os-Os bond with an Os-Os distance of 304 pm. In contrast, the osmocenium cation of the pentamethylcyclopentadienyl ligand [OsCp ^* ₂ ] ⁺ is stable as a monomer.

use

In 2009 Horst Kunkely and Arnd Vogler reported on the possibility of photolytic water splitting with the help of osmocene as a catalyst.

Individual evidence

1. ↑ ^{a b c} data sheet Osmocen at AlfaAesar, accessed on January 3, 2012 ( PDF )(JavaScript required) .
2. ↑ ^{a b} F. Jellinek: The structure of the osmocene. In: Journal of Nature Research B . 14, 1959, pp. 737-738 ( online ).
3. ↑ Entry on bis (cyclopentadienyl) osmium at ChemicalBook , accessed December 30, 2011.
4. ↑ ^{a b} J. CA Bobyens, DC Levendis, Michael I. Bruce, Michael L. Williams: Crystal structure of osmocene, Os (η-C ₅ H ₅ ) ₂ . In: Journal of Crystallographic and Spectroscopic Research . tape 16 , no. 4 , 1986, pp. 519-524 , doi : 10.1007 / BF01161040 .
5. ↑ EO Fischer, Heinrich Grumbert: About aromatic complexes of metals, XXIX. Di-cyclopentadienyl osmium . In: Chem. Ber. tape 92 , no. 9 , 1959, pp. 2302-2309 , doi : 10.1002 / cber.19590920948 .
6. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , pp. 1699-1703.
7. ↑ ^{a b} Christoph Elschenbroich: Organometallchemie . BG Teubner Verlag, 2008, ISBN 978-3-8351-0167-8 ( page 458 in the Google book search).
8. ^ Sally A. Kur, Arnold L. Rheingold, Charles H. Winter: Synthesis, Characterization, and Halogenation of Decakis (acetoxymercurio) osmocene. Crystal and Molecular Structure of Decachloroosmocene . In: Inorg. Chem. Band 34 , no. 1 , 1995, p. 414-416 , doi : 10.1021 / ic00105a067 .
9. ↑ Michael W. Droege, W. Dean Harman, Henry Taube: Higher oxidation state chemistry of osmocene: dimeric nature of the osmocenium ion . In: Inorg. Chem. Band 26 , no. 8 , 1987, pp. 1309-1315 , doi : 10.1021 / ic00255a023 .
10. ^ Didier Astruc: Organometallic Chemistry and Catalysis . Springer-Verlag, Berlin Heidelberg, 2007, ISBN 978-3-540-46128-9 ( pages 251-270 in the Google book search).
11. ↑ Horst Kunkely and Arnd Vogler: Splitting water through light with osmocs as a photocatalyst . In: Angewandte Chemie . tape 121 , no. 9 , February 16, 2009, p. 1713-1715 , doi : 10.1002 / anie.200804712 .