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| Solubility = insoluble, does not react with water | Solubility = insoluble, does not react with water
| Solvent = chlorocarbons | Solvent = chlorocarbons
| SolubleOther = sparingly soluble (<i>ca.</i> 0.5 g/L) | SolubleOther = sparingly soluble (''ca.'' 0.5 g/L)
}} }}
|Section3={{Chembox Hazards |Section3={{Chembox Hazards
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: NpCl<sub>4</sub> + 2 K<sub>2</sub>(C<sub>8</sub>H<sub>8</sub>) → Np(C<sub>8</sub>H<sub>8</sub>)<sub>2</sub> + 4 KCl : NpCl<sub>4</sub> + 2 K<sub>2</sub>(C<sub>8</sub>H<sub>8</sub>) → Np(C<sub>8</sub>H<sub>8</sub>)<sub>2</sub> + 4 KCl


The same reaction conditions have been routinely reproduced since then for the synthesis of the compound.<ref name=":2" /><ref name=":3" /> The same reaction conditions have been routinely reproduced since then for the synthesis of the compound.<ref name=":2" /><ref name=":3" />


The three actinocenes ], neptunocene, and ] share virtually identical chemistry: they do not react in the presence of water or dilute base, but are very air-sensitive, quickly forming oxides.<ref name=":0" /><ref name=":1" /><ref name=":2" /> All three are only slightly soluble (up to about 10<sup>-3</sup> M concentrations) in aromatic or chlorinated solvents such as ], ], ] or ].<ref name=":0" /><ref name=":1" /><ref name=":3" /><ref name="Yoshida750" /> The three actinocenes ], neptunocene, and ] share virtually identical chemistry: they do not react in the presence of water or dilute base, but are very air-sensitive, quickly forming oxides.<ref name=":0" /><ref name=":1" /><ref name=":2" /> All three are only slightly soluble (up to about 10<sup>−3</sup> M concentrations) in aromatic or chlorinated solvents such as ], ], ] or ].<ref name=":0" /><ref name=":1" /><ref name=":3" /><ref name="Yoshida750" />


==References== ==References==

Revision as of 23:41, 3 June 2021

Neptunocene
Names
IUPAC name Bis(η-cyclooctatetraenyl)neptunium(IV)
Other names Neptunium cyclooctatetraenide
Np(COT)2
Identifiers
CAS Number
3D model (JSmol)
InChI
  • InChI=1S/2C5H5.Np/c2*1-2-4-5-3-1;/h2*1-5H;/q2*-1;+2Key: FXDJOXAJBKYPFW-UHFFFAOYSA-N
SMILES
  • .C1=CC=CC=CC=C1.C1=CC=CC=CC=C1
Properties
Chemical formula C16H16Np
Molar mass 445 g·mol
Appearance dark brown crystals as a solid, yellow in dilute solution
Solubility in water insoluble, does not react with water
Solubility in chlorocarbons sparingly soluble (ca. 0.5 g/L)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards radiation hazard, pyrophoric
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references
Chemical compound

Neptunocene, Np(C8H8)2, is an organoneptunium compound composed of a neptunium atom sandwiched between two cyclooctatetraenide (COT) rings. As a solid it has a dark brown/red colour but it appears yellow when dissolved in chlorocarbons, in which it is sparingly soluble. The compound is quite air-sensitive.

It was one of the first organoneptunium compounds to be synthesised, and is a member of the actinocene family of actinide-based metallocenes.

Structure

The sandwich structure of neptunocene has been determined by single crystal XRD. The COT rings are found to be planar with 8 equivalent C–C bonds of 1.385 Å length, and sit parallel in an eclipsed conformation. The Np–COT distance (to the ring centroid) is 1.909 Å and the individual Np–C distances are 2.630 Å.

Neptunocene assumes a monoclinic crystal structure (P21/n space group) which is isomorphous to uranocene and thorocene but not to plutonocene.

Synthesis and properties

Neptunocene was first synthesised in 1970 by reacting neptunium(IV) chloride (NpCl4) with dipotassium cyclooctatetraenide (K2(C8H8)) in diethyl ether or THF:

NpCl4 + 2 K2(C8H8) → Np(C8H8)2 + 4 KCl

The same reaction conditions have been routinely reproduced since then for the synthesis of the compound.

The three actinocenes uranocene, neptunocene, and plutonocene share virtually identical chemistry: they do not react in the presence of water or dilute base, but are very air-sensitive, quickly forming oxides. All three are only slightly soluble (up to about 10 M concentrations) in aromatic or chlorinated solvents such as benzene, toluene, carbon tetrachloride or chloroform.

References

  1. ^ Karraker, David G.; Stone, John Austin.; Jones, Erwin Rudolph.; Edelstein, Norman. (1970). "Bis(cyclooctatetraenyl)neptunium(IV) and bis(cyclooctatetraenyl)plutonium(IV)". Journal of the American Chemical Society. 92 (16): 4841–4845. doi:10.1021/ja00719a014. ISSN 0002-7863.
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 1278–1280. ISBN 9780750633659.
  3. ^ Eisenberg, David C.; Streitwieser, Andrew; Kot, Wing K. (1990). "Electron transfer in organouranium and transuranium systems". Inorganic Chemistry. 29 (1): 10–14. doi:10.1021/ic00326a004. ISSN 0020-1669.
  4. ^ Ridder, D. J. A. De; Rebizant, J.; Apostolidis, C.; Kanellakopulos, B.; Dornberger, E. (1996). "Bis(cyclooctatetraenyl)neptunium(IV)". Acta Crystallographica Section C. 52 (3): 597–600. doi:10.1107/S0108270195013047. ISSN 1600-5759.
  5. ^ Yoshida, Zenko; Johnson, Stephen G.; Kimura, Takaumi; Krsul, John R. (2006). "Neptunium". In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (PDF). Vol. 3 (3rd ed.). Dordrecht, the Netherlands: Springer. pp. 699–812. doi:10.1007/1-4020-3598-5_6.
Neptunium compounds
Np(III)
Np(IV)
Organoneptunium(IV) compounds
Np(V)
Np(VI)
Np(VII)
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