C_αC_α‐Coupling of Two {(CO)₅CrCNEt₂} Fragments by Reductive Dimerization of a Cationic Carbyne Complex

Abstract

The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1036. DOI:

Bimetallic Complexes with Conjugated C4, C6, C10, and C14 Bridges: Synthetic Routes to Alkynediyl-Bridged Bis(carbene) Complexes

“…The central C-C distance (1.463(9) Å) corresponds to a C(sp 2 )-C(sp 2 ) single bond and agrees well with that in the related chromium complex [(CO) 5 Crd C(NEt 2 )(Et 2 N)CdCr(CO) 5 ] (1.480(9) Å). 19 To prevent unfavorable steric interactions, the WdC distances (2.281 (7) and 2.295(7) Å) are rather long and are significantly longer than in typical aminocarbene complexes such as [(CO) 5 WdC(NHMe)Ph] (2.186(22) Å) 33 and [(CO) 5 WdC(NMe 2 )CtCSiMe 3 ] (2.224 Å). 34 Compared to a C(sp 2 )-N(sp 2 ) single bond, 35 the C(carbene)-N bonds are rather short.…”

“…1b,2a Only two complexes of type I have been reported until now. Both compounds, [(CO) 5 MdC(NEt 2 )(Et 2 N)CdM(CO) 5 ] (M ) Cr, 19 W 20 ), were obtained by reductive dimerization of the cationic carbyne complexes [(CO) 5 ΜtCNEt 2 ]BF 4 . However, several complexes with unsaturated cyclic π-conjugated carbon bridges linking two metal-carbene fragments L n MdC(R) are known.…”

Di- and Polymetallic Heteroatom Stabilized (Fischer) Metal Carbene Complexes

“…Apparently, the reductive dimerization of a cationic carbyne complex with concomitant C R -C R coupling can become the dominating reaction, competing with the addition of the nucleophile to the carbyne carbon atom, when strongly reducing nucleophiles are used. 91 The reaction of complex 250 with Li[TePh] afforded the expected carbene complex 254. This complex was unstable and rearranged to a new carbyne complex 255 upon standing at room temperature or to mer-256 if PPh 3 is present in the reaction medium (Scheme 51).…”

Syntheses, Spectroscopy, and Redox Properties of Fluoro−Carbyne and Derived Fluoro−Vinylidene Complexes of Rhenium and of Analogous Chloro Complexes

“…Moreover, since very few studies of the redox properties of carbyne or carbene complexes have been reported, − in spite of their expected significance in terms of defining the electron-donor/acceptor properties of those ligands 17a and of their promising redox-induced chemistry, we have also investigated the electrochemical behavior of those rhenium carbyne and vinylidene complexes, which is also described in detail.…”

“…Moreover, since very few studies of the redox properties of carbyne or carbene complexes have been reported, [16][17][18][19][20][21][22][23][24][25][26][27] in spite of their expected significance in terms of defining the electron-donor/acceptor properties of those ligands 17a and of their promising redox-induced chemistry, we have also investigated the electrochemical behavior of those rhenium carbyne and vinylidene complexes, which is also described in detail. Some preliminary results have already been briefly reported by us, 28 including the crystal structure of 1b, 28a a complex that was then obtained fortuitously in an extremely low yield as a side product.…”