Alkylidyne complexes are organometallic compounds containing a triple bond between a carbon atom and a transition metal. There are two main types: Fischer alkylidynes and Schrock alkylidynes. Fischer complexes contain later transition metals and heteroatoms, making the carbon atom electrophilic. Schrock complexes contain early transition metals, strong donating ligands, and less than 18 electrons, making the carbon atom nucleophilic. Alkylidyne complexes can be synthesized via several routes, including from low valent metal complexes, alkylidene complexes, or through double halide abstraction from dichlorocarbene compounds.

1. By
fariha un nisa
BS CHEMISTRY UOG
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2. Alkylidyne complexes
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3. History
 In early 1970’s Richard R. Schrock , former student of John Osborn
at Harvard made important discovery of first nucleophillic
alkylidyne complex
 In 1973, E.O Fischer synthesized first metal carbyne complex
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4. Introduction :
 Definition:
 Transition metal carbyne complexes are organometallic
compounds with a triple bond between carbon and the transition
metal
 Triple bond consists of a σ-bond and two π-bonds.
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5. Cont.
 Also called metal alkylidynes
 length of the M-C bond varies between 1.65 and 1.90 Ǻ depending
on the metal.
 Monomeric metal carbyne complexes exhibit linear M–C–R
linkages according to X-ray crystallography.
 M–C distances are typically shorter than the M–C bonds found in
metal carbenes.
 bond angle :170° to 180°.
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6. Classification of Alkylidyne complexes:
 Fischer alkylidynes
 stabilized by heteroatoms and bonded with low oxidation state
transition metals (usually later transition metals).
 Have π–acceptor ligands on the metal making the carbyne
essentially electrophilic.

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7. Cont.
Tungsten is a very common metal used to make Fischer
carbynes. Fischer is very famous in the organometallic field, winning
the Nobel Prize in 1973.

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8. Cont.
 Schrock alkylidynes:
 Have no heteroatoms, and are found with high oxidation state
metals (early transition metals).
 The other ligands on the metal are usually strong σ-donors, which
makes the carbon essentially nucleophilic.
 They usually form complexes with less than 18 electrons and the
metals tend to be d0.
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9. cont.
 The Schrock carbyne is an example of a quartet carbyne. It forms 3
covalent bonds to the metal because it has 3 unpaired electron.
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10. Synthesis of alkylidyne complexes:
 From low valent metal complexes:
Metal like W and molebdenum undergo synthesis of alkylidynes by
this method
 X= cl-,Br- and R= Alkyl group
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11. synthesis cont.
From alkylidene
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12. Cont.
Other routes:
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13. Cont.
From dichlorocarbene:
Highly reactive compound. Treatment with aryl lithium leads to double halide abstraction
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14. References:
 Manfred bochmann, organometallics 1, alkylidene and alkylidyne
complexes , pg(84-87)
 Inorganic chemistry by Miessler and Tarr, 3rd edition, chapter
13,pg(510-512)
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