Organochromium chemistry

From Wikipedia, the free encyclopedia

Chromocene

Organochromium chemistry is a branch of organometallic chemistry that deals with organic compounds containing a chromium to carbon bond and their reactions [1] [2]. The field is of some relevance to organic synthesis.

Contents

[edit] History

The first organochromium compound was described in 1919 by Franz Hein [3]. He reacted phenylmagnesium bromide with chromium(III) chloride to a new product (after hydrolysis) which he incorrectly identified as pentaphenyl chromium bromide (Ph5CrBr). Years later, in 1957 H.H. Zeiss et al. repeated Heins experiments and correctly arrived at a cationic bisarene chromium sandwich compound (Ar2Cr+) [4]. Bis(benzene)chromium itself was discovered around the same time in 1956 by Ernst Otto Fischer by reaction of chromium(III) chloride, benzene and aluminum chloride [5] [6]. The related compound chromocene was discovered a few years earlier in 1953 also by Fischer [7].


dibenzenechromium synthesis

In another development, Anet and Leblanc also in 1957 prepared a benzyl chromium solution from benzyl bromide and chromium perchlorate [8]. This reaction type is oxidative addition of chromium into the carbon-bromine bond, a process which was shown by Kochi [9] [10] to be a case of double single electron transfer first to the benzyl free radical and then to the benzyl anion.

Organochromium Anet Leblanc 1957

G. Wilke et al. introduced tris-(η-allyl)chromium in 1963 as an early Ziegler-Natta catalyst (but not successful in the long run) [11] Chromocene compounds were first employed in ethylene polymerization in 1972 by Union Carbide [12] and organochromium catalysts are used today in the industrial production of high-density polyethylene.

The organochromium compound (phenylmethoxycarbene)pentacarbonylchromium (Ph)(OCH3)C=Cr(CO)5 was the first carbene ever structurally characterized (X-ray diffraction) by Fischer in 1967 (now called a Fischer carbene) [13]. The first ever carbyne, this one also containing chromium, made its debute in 1973 [14]

Fischer carbenes and carbynes

Two organic reactions involving chromium with use in organic synthesis are the Nozaki-Hiyama-Kishi reaction (1977) (transmetallation with organonickel intermediate) and the Takai olefination (1986)(oxidation of Cr(II) to Cr(III) while replacing halogens).

[edit] Organochromium compounds

Organochromium compounds can be divided into these broad compound classes:


[edit] Ethylene polymerization

Chromonium catalysts are important in ethylene polymerization [16]. Two industrial catalysts exist: the Phillips catalyst is deposited chromium(III) oxide on silica with activation by hydrogen. A Union Carbide catalyst is based on silica and chromocene. Exactly how these catalysts work is unclear. One model system describes it as coordination polymerization:

Ethylene polymerization by chromium

With two THF ligands the catalyst is stable but in dichloromethane one ligand is lost to form a 13 electron chromium intermediate. This enables side-on addition of a ethylene unit and a polymer chain can grow by migratory insertion.

[edit] See also

  • Other bonds of carbon with elements in the periodic table:
CH He
CLi CBe CB CC CN CO CF Ne
CNa CMg CAl CSi CP CS CCl Ar
CK CCa CSc CTi CV CCr CMn CFe CCo CNi CCu CZn CGa CGe CAs CSe CBr Kr
CRb CSr CY CZr CNb CMo CTc CRu CRh CPd CAg CCd CIn CSn CSb CTe CI Xe
CCs CBa CHf CTa CW CRe COs CIr CPt CAu CHg CTl CPb CBi CPo CAt Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo
↓
La CCe Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa CU Np Pu Am Cm Bk Cf Es Fm Md No Lr


Chemical bonds to carbon
Core organic chemistry many uses in chemistry.
Academic research, but no widespread use Bond unknown / not assessed.


[edit] References

  1. ^ Review: Carbon-Carbon Bond Formations Involving Organochromium(III) Reagents Furstner, A. Chem. Rev.; (Review); 1999; 99(4); 991-1046. doi:10.1021/cr9703360
  2. ^ Review: From Hein to Hexene: Recent Advances in the Chemistry of Organochromium -Complexes Jolly, P. W. Acc. Chem. Res.; (Article); 1996; 29(11); 544-551. doi:10.1021/ar9502588
  3. ^ Notiz über Chromorganoverbindungen (p 195-196) F. Hein Berichte der deutschen chemischen Gesellschaft (A and B Series) Volume 52, Issue 1 , Pages 195 - 196 1919 doi:10.1002/cber.19190520126
  4. ^ π-Complexes of the Transition Metals. I. Hein's Polyaromatic Chromium Compounds Harold H. Zeiss, Minoru Tsutsui J. Am. Chem. Soc.; 1957; 79(12); 3062-3066. doi:10.1021/ja01569a019
  5. ^ Zur Frage der Struktur der Chrom-phenyl-Verbindungen. Über Aromatenkomplexe von Metallen VI (p 1809-1815) E. Otto Fischer, Dietlinde Seus Chemische Berichte Volume 89, Issue 8 , Pages 1809 - 1815 1956 doi:10.1002/cber.19560890803
  6. ^ Zur Frage der Struktur der Chrom-phenyl-Verbindungen. Bemerkungen zur Abhandlung von E. O. Fischer und D. Seus (p 1816-1821) Fr. Hein Chemische Berichte Volume 89, Issue 8 , Pages 1816 - 1821 1956 doi:10.1002/cber.19560890804
  7. ^ Fischer, E. O.; Hafner, W. Z. Naturforsch. 1953, 8b, 444.
  8. ^ A NOVEL ORGANO-CHROMIUM COMPOUND F. A. L. Anet, E. Leblanc J. Am. Chem. Soc.; 1957; 79(10); 2649-2650 doi:10.1021/ja01567a080
  9. ^ Reduction of Organic Halides by Chromium(II). Mechanism of the Formation of Benzylchromium Ion Jay K. Kochi, Dennis D. Davis J. Am. Chem. Soc.; 1964; 86(23); 5264-5271. doi:10.1021/ja01077a044
  10. ^ Stereochemistry of reductive elimination by chromium(II) complexes Jay K. Kochi, David M. Singleton J. Am. Chem. Soc.; 1968; 90(6); 1582-1589. doi:10.1021/ja01008a032
  11. ^ Cyclooligomerisation von Butadien und Übergangsmetall--Komplexe Angewandte Chemie Volume 75, Issue 1, Date: 7. Januar 1963, Pages: 10-20 G. Wilke, Nach B. ArbeitenBogdanovi, P. Borner, H. Breil, P. Hardt, P. Heimbach, G. Herrmann, H.-J. Kaminsky, W. Keim, M. Kröner, Herbert Müller, Ernst Willi Müller, W. Oberkirch, J. Schneider, J. Stedefeder, K. Tanaka, K. Weyer, G. Wilke doi:10.1002/ange.19630750104
  12. ^ Chromocene catalysts for ethylene polymerization: Scope of the polymerization Journal of Polymer Science Part A-1: Polymer Chemistry Volume 10, Issue 9 , Pages 2621 - 2637 Frederick J. Karol, George L. Karapinka, Chisung Wu, Alan W. Dow, Robert N. Johnson, Wayne L. Carrick 1972 doi:10.1002/pol.1972.150100910
  13. ^ Übergangsmetall-Carben-Komplexe, II. Phenylmethoxycarben- und Methylmethoxycarben-pentacarbonyl-chrom, -molybdän, -wolfram und -cyclopentadienyl-dicarbonyl-mangan (p 2445-2456) Ernst Otto Fischer, Alfred Maasböl Chemische Berichte Volume 100, Issue 7 1967 doi:10.1002/cber.19671000744
  14. ^ trans-Halogeno-alkyl(aryl)carbin-tetracarbonyl-Komplexe von Chrom, Molybdän und Wolfram-Ein neuer Verbindungstyp mit Übergangsmetall-Kohlenstoff-Dreifachbindung (p 618-620) Ernst Otto Fischer, Gerhard Kreis, Cornelius G. Kreiter, Jörn Mülle, Gottfried Huttner, Hans Lorenz Angewandte Chemie Volume 85, Issue 14 1973 doi:10.1002/ange.19730851407
  15. ^ Chemistry of organochromium(III) complexes James H. Espenson Acc. Chem. Res.; 1992; 25(5); 222-227. doi:10.1021/ar00017a003
  16. ^ Organochromium(III) chemistry: a neglected oxidation state Klaus H. Theopold Acc. Chem. Res.; 1990; 23(8); 263-270. doi:10.1021/ar00176a005