Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
Organometallic Chemistry
*Organometallic chemistry:- The chemistry of compounds that contain
one or more metal–carbon bonds.
*Historical Background
*In (1760) Cadet of Paris military pharmacy, works on invisible inks
based on cobalt salt solutions. For their preparation, he uses cobalt
minerals that contain arsenic.
* The first olefin complex synthesized in (1827) by Zeise, who obtained
yellow needle-like crystals after refluxing a mixture of PtCl 4 and PtCl2 in
ethanol, followed by addition of KCl solution. Zeise’s salt was the first
compound identified as containing an organic molecule attached to a
metal using the pi electrons of the organic molecule. It is an ionic
compound of formula K[Pt(C2H4)Cl3].H2O [Potassium
trichloro(ethene)platinate(II)]; the structure of the anion, as shown
bellow; is based on a square plane, with three chloro ligands occupying
corners of the square and the ethylene occupying the fourth corner, but
perpendicular to the plane.
1
,Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
Anion of Zeise’s Salt
* 1852 Frankland prepares the important alkylmercury halides.
additionally: (C2H5)4Sn, (CH3)3B (1860). Frankland also introduced the
concept of valency (“combining power”) and the term “organometallic”.
*At (1852) C. J. Löwig and M. E. Schweizer in Zürich first prepare
(C2H5)4Pb from ethyl iodide and Na/Pb alloy. In a similar manner, they
also obtain (C2H5)3Sb and (C2H5)3Bi.
*In (1859) W. Hallwachs and A. Schafarik generate alkylaluminum
iodides
*In (1863) C. Friedel and J. M. Crafts prepare organochlorosilanes:
* The first organometallic compound containing the carbonyl ligand,
[PtCl2(CO)2] was discovered by P. Schützenberger in (1868).
2
,Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
* In (1890), Mond reported the preparation of the first binary metal
carbonyl compound, Ni(CO)4, a compound that became commercially
useful for the purification of nickel.
* Reactions between magnesium and alkyl halides, performed by Barbier
in (1898) and subsequently by Grignard led to the synthesis of alkyl
magnesium complexes now known as Grignard reagents, which used
extensively in organic synthesis.
*In (1909) W. J. Pope: prepared [(CH3)3PtI], the first σ-
organotransition-metal compound.
* In 1951, in an attempt to synthesize fulvalene from cyclopentadienyl
bromide, Kealy and Pauson reacted the Grignard reagent cyclo-
(C5H5)MgBr with FeCl3. This reaction did not yield fulvalene but an
orange solid having the formula (C5H5)2Fe, ferrocene. For each of the
cyclopentadienyl rings, all five of the C atoms are equidistant from the
metal ion, so that the two ring systems are parallel to each other just like
the slices of bread in a sandwich, with the metal stuck in between them.
The initial study indicated that the rings were in a staggered
conformation. Electron diffraction studies of gas-phase ferrocene, on the
3
, Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
other hand, showed the rings to be eclipsed, or very nearly so. More
recent X-ray diffraction studies of solid ferrocene have identified several
crystalline phases, with an eclipsed conformation at 98 K and with
conformations having the rings slightly twisted (Skew) in higher-
temperature crystalline modifications.
* Fischer’s group can also take credit for the discovery of the first metal–
carbon double bond, or carbene compound, [(CO)5W=C(OCH3)Ph], in
1964 and the first metal–carbon triple bond, or carbyne,
[(CO)4XCr≡CPh], in 1973.
*An other examples about sandwich compounds have been shown in the
following figure;
4
Organometallic Chemistry
*Organometallic chemistry:- The chemistry of compounds that contain
one or more metal–carbon bonds.
*Historical Background
*In (1760) Cadet of Paris military pharmacy, works on invisible inks
based on cobalt salt solutions. For their preparation, he uses cobalt
minerals that contain arsenic.
* The first olefin complex synthesized in (1827) by Zeise, who obtained
yellow needle-like crystals after refluxing a mixture of PtCl 4 and PtCl2 in
ethanol, followed by addition of KCl solution. Zeise’s salt was the first
compound identified as containing an organic molecule attached to a
metal using the pi electrons of the organic molecule. It is an ionic
compound of formula K[Pt(C2H4)Cl3].H2O [Potassium
trichloro(ethene)platinate(II)]; the structure of the anion, as shown
bellow; is based on a square plane, with three chloro ligands occupying
corners of the square and the ethylene occupying the fourth corner, but
perpendicular to the plane.
1
,Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
Anion of Zeise’s Salt
* 1852 Frankland prepares the important alkylmercury halides.
additionally: (C2H5)4Sn, (CH3)3B (1860). Frankland also introduced the
concept of valency (“combining power”) and the term “organometallic”.
*At (1852) C. J. Löwig and M. E. Schweizer in Zürich first prepare
(C2H5)4Pb from ethyl iodide and Na/Pb alloy. In a similar manner, they
also obtain (C2H5)3Sb and (C2H5)3Bi.
*In (1859) W. Hallwachs and A. Schafarik generate alkylaluminum
iodides
*In (1863) C. Friedel and J. M. Crafts prepare organochlorosilanes:
* The first organometallic compound containing the carbonyl ligand,
[PtCl2(CO)2] was discovered by P. Schützenberger in (1868).
2
,Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
* In (1890), Mond reported the preparation of the first binary metal
carbonyl compound, Ni(CO)4, a compound that became commercially
useful for the purification of nickel.
* Reactions between magnesium and alkyl halides, performed by Barbier
in (1898) and subsequently by Grignard led to the synthesis of alkyl
magnesium complexes now known as Grignard reagents, which used
extensively in organic synthesis.
*In (1909) W. J. Pope: prepared [(CH3)3PtI], the first σ-
organotransition-metal compound.
* In 1951, in an attempt to synthesize fulvalene from cyclopentadienyl
bromide, Kealy and Pauson reacted the Grignard reagent cyclo-
(C5H5)MgBr with FeCl3. This reaction did not yield fulvalene but an
orange solid having the formula (C5H5)2Fe, ferrocene. For each of the
cyclopentadienyl rings, all five of the C atoms are equidistant from the
metal ion, so that the two ring systems are parallel to each other just like
the slices of bread in a sandwich, with the metal stuck in between them.
The initial study indicated that the rings were in a staggered
conformation. Electron diffraction studies of gas-phase ferrocene, on the
3
, Organometallic chemistry…. (2016-first course-2017) …. Fourth Class
other hand, showed the rings to be eclipsed, or very nearly so. More
recent X-ray diffraction studies of solid ferrocene have identified several
crystalline phases, with an eclipsed conformation at 98 K and with
conformations having the rings slightly twisted (Skew) in higher-
temperature crystalline modifications.
* Fischer’s group can also take credit for the discovery of the first metal–
carbon double bond, or carbene compound, [(CO)5W=C(OCH3)Ph], in
1964 and the first metal–carbon triple bond, or carbyne,
[(CO)4XCr≡CPh], in 1973.
*An other examples about sandwich compounds have been shown in the
following figure;
4
