trans‐Halogeno[alkyl(aryl)carbyne]tetracarbonyl Complexes of Chromium, Molybdenum, and Tungsten —A New Class of Compounds Having a Transition Metal‐Carbon Triple Bond

Structure and Bonding of Low‐Valent (Fischer‐Type) and High‐Valent (Schrock‐Type) Transition Metal Carbyne Complexes

“…In 1973, Fischer et al succeeded in isolating [Br(CO) 4 W(CMe)]. [2] Five years later, Schrock reported the synthesis of [CpCl(PMe 3 )MeTa(CPh)]. [3] Although the distinction between the two types of carbyne or alkylidyne complexes is less clear-cut than in case of the carbene complexes, it has become a useful model to explain the differences in the chemical behaviour of Fischer and Schrock carbyne complexes.…”

Multiple Metal–Carbon Bonds for Catalytic Metathesis Reactions (Nobel Lecture)

“…The most common of these decomposition reactions involves transfer of a b hydrogen atom, from a metal-bound ethyl group (MÀCH 2 CH 3 ) for example, to the metal center (M) to yield a metal hydride and an alkene. The relative stabilities of high-oxidation-state "homoleptic" or "peralkyl" compounds such as [M{CH 2 Si-(CH 3 ) 3 } 4 ], [M(CH 2 C 6 H 5 ) 4 ], and [M{CH 2 C(CH 3 ) 3 } 4 ] (M = Ti, Zr, or Hf; Scheme 2), were rationalized on the basis of the fact that unlike a compound having an ethyl ligand, the alkyl ligands in these species lack b hydrogen atoms and so of course cannot undergo decomposition processes that involve b hydrogen atoms.[ 6 ] is stable at 22 8C. The methyl carbon is a with respect to the metal center; there is no b carbon atom and so no b hydrogens.…”

“…The relative stabilities of high-oxidation-state "homoleptic" or "peralkyl" compounds such as [M{CH 2 Si-(CH 3 ) 3 } 4 ], [M(CH 2 C 6 H 5 ) 4 ], and [M{CH 2 C(CH 3 ) 3 } 4 ] (M = Ti, Zr, or Hf; Scheme 2), were rationalized on the basis of the fact that unlike a compound having an ethyl ligand, the alkyl ligands in these species lack b hydrogen atoms and so of course cannot undergo decomposition processes that involve b hydrogen atoms. [7] In 1973 Wilkinson published the synthesis of [W(CH 3 ) 6 ]. [8] Unlike [M(CH 3 ) 4 ] species (where M = Ti, Zr, or Hf) [W(CH 3 ) 6 ] is stable at 22 8C.…”

“…[6] It was clear that metal-carbon single bonds were of great importance in the emerging area of homogeneous catalysis. However, no catalytic reactions involving species that contain metalcarbon double or triple bonds were known.…”

Triple Bonds of the Heavy Main‐Group Elements: Acetylene and Alkylidyne Analogues of Group 14

“…Although transition-metal-carbyne or -alkylidyne complexes have been known since the work of Fischer and co-workers in 1973, [21] it was not until 1996 that Power et al achieved the synthesis, by the surprisingly simple route of salt elimination, and characterization of the germylyne-molybdenum complex 14.…”