Zincocene

Structural formula
General
Surname	Zincocene
other names	Bis ( cyclopentadienyl ) zinc (II)
Molecular formula	C 10 H 10 Zn
Brief description	colorless solid
External identifiers / databases
CAS number 11077-31-9 Wikidata Q18666112
properties
Molar mass	195.57 g mol −1
solubility	slightly soluble in organic solvents
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Zincocene, or bis ( cyclopentadienyl ) zinc (II) according to the IUPAC nomenclature , is an organometallic compound from the metallocenes family .

history

Zinkocene was first produced in 1969 in Ernst Otto Fischer's group and described as a colorless, diamagnetic solid.

Extraction and presentation

Zinkocene is produced by reacting anhydrous zinc (II) chloride with cyclopentadienyl sodium , in diethyl ether as a solvent :

${\displaystyle \mathrm {ZnCl_{2}\ +\ 2\ Na(C_{5}H_{5})\ {\xrightarrow[{Diethylether}]{}}\ Zn(C_{5}H_{5})_{2}\ +\ 2\ NaCl} }$

properties

Due to its salt-like character, zincocene is insoluble in organic solvents such as benzene , petroleum ether or methylene chloride , while it can be extracted with diethyl ether. It sublimes in a high vacuum with partial decomposition at 100–130 ° C and sinters with a dark color at 190–200 ° C. It is extremely sensitive to air and hydrolyzes immediately in aqueous media.

While Ernst Otto Fischer initially assumed a sandwich structure as in magnesocene based on the IR spectrum , it was possible in 1984 to prove by X-ray structure analysis that it polymerizes in a chain structure in which cyclopentadienyl rings and zinc atoms are alternately linked and an additional terminal cyclopentadienyl ring is bound to each zinc atom . Each of the three cyclopentadienyl rings is η ² -coordinated. If the cyclopentadienyl rings contain further substituents, monomeric complexes can be synthesized. Bis (pentamethylcyclopentadienyl) zinc ZnCp ^* ₂ has an η ¹ , η ⁵ coordination in the gas phase , which corresponds to the slipped sandwich structure of beryllocene . In solution, on the other hand, it only shows a ¹ H-NMR signal, which means a rapid fluctuation between the η ¹ and η ⁵ coordination of the two Cp ^* rings. 2003 Arne Haaland among others have shown that Zinkocen ZnCp ₂ in the gas phase also a η ¹ , η ⁵ - slipped sandwich structure has.

Individual evidence

1. ↑ ^{a b c d} Ernst Otto Fischer, Hermann Pankraz Hofmann, Arnoreiber: Di-cyclopentadienyl-zinc. In: Journal of Nature Research B . 14, 1959, pp. 599-600 ( online ).
2. ↑ W. Strohmeier, H. Landsfeld, F. Gernert, W. Langhäuser: Di-methylcyclopentadienyl-magnesium, di-methylcyclopentadienyl-zinc and tri-methylcyclopentadienyl-lanthanum . In: Z. anorg. gen. Chem. Band 307 , no. 3-4 , 1961, pp. 120-132 , doi : 10.1002 / zaac.19613070303 .
3. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
4. ↑ Dirk Bentz: Complexes of zinc, cadmium, lanthanum, cerium and samarium with bulky alkylcyclopentadienyl ligands. Dissertation 2005, urn : nbn: de: hbz: 386-kluedo-19006
5. ↑ Peter HM Budzelaar, Jaap Boersma, Gerrit JM van der Kerk, Anthony L. Spek, Albert JM Duisenberg: The structure of dicyclopentadienylzinc . In: J. Organomet. Chem. Band 281 , no. 2-3 , 1985, pp. 123-130 , doi : 10.1016 / 0022-328X (85) 87100-X .
6. ↑ Christoph Elschenbroich: Organometallchemie . BG Teubner Verlag, 2008, ISBN 978-3-8351-0167-8 ( page 73 in the Google book search).
7. ↑ Arne Haaland, Svein Samdal, Natalya V. Tverdova, Georgii V. Girichev, Nina I. Giricheva, Sergej A. Shlykov, Oleg G. Garkusha, Boris V. Lokshin: The molecular structure of dicyclopentadienylzinc (zincocene) determined by gas electron diffraction and density functional theory calculations: η ⁵ , η ⁵ , η ³ , η ³ or η ⁵ , η ¹ coordination of the ligand rings? In: J. Orgonomet. Chem. Band 684 , no. 1–2 , 2003, pp. 351-358 , doi : 10.1016 / S0022-328X (03) 00770-8 .