From Carbyne Complexes

When imines are the nucleophiles used, the initially formed iminium intermediates can undergo intramolecular electrophilic alkylation of the other ligands (e.g. Entry 2, Table 2.10 see also [143]). In addition to this, carbyne complexes can also react with azides to give metallatriazoles [185,186] (Entry 6, Table 2.10). 

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From Carbyne Complexes. Addition of HC1 across the metal-carbon triple bonds of Ru and Os d8 arylcarbyne complexes yield stable, neutral secondary alkylidene complexes ... 

Table 2.10. Heteroatom-substituted carbene complexes prepared from carbyne complexes.

Some rare cases of cyclopropane formation from carbyne complexes have been reported. 

A series of general headings can be applied to the synthetic routes used for generating vinylidene complexes (i) reactions of alkynes with labile and/or coordinatively unsaturated species, (ii) reactions with alkynes in the presence of a halide abstracting agent, (iii) formation from alkynyl complexes, and (iv) formation from carbyne complexes. 

A related example from the literature is the reaction of [(CO)4Cr(SnPh3)9] with [Me2N=CCl2]+, which yields the carbyne complex (CO)4(SnPh3)CrsCNMe, [17],... 

Halide addition to a cationic carbyne complex, [L M=CR]+, or halogen oxidation of a low oxidation state carbyne complex are both potential routes to monohalocarbene species. Examples of the first process are well known for carbyne complexes from Groups 6 and 7 of the periodic table (120), e.g.,... 

The unusual peroxycarbonyl ligand in these complexes was first charac-terized in Os(C(O)O0)Cl(NO)(PPh3)2, the product of oxygenation of 95 (39). The peroxycarbonyl ligand is cleaved from 96 by reaction with HC1, and the octahedral, d6 carbyne complex 98 can be isolated. Similar treatment of 97 affords cationic complex 99 (131). ... 

The X-ray structure determination of 107 reveals that the osmium-carbon bond length is increased by 0.07 A on going from the parent carbyne complex 79 to the silver adduct 107. This may be contrasted with the weaker interaction between the metal-carbon bond and the Aul fragment in Os(CH2AuI)Cl(NO)(PPh3)2 (see Section IV,C,1). 

Experimental Procedure 3.1.4. Preparation of a Molybdenum Vinylidene Complex from a Carbyne Complex Tetrabutylanunoniuih Cyano(ethoxycarbonyl) vinylidene (dicarbonyl) hydro-tris(3,5-dimethyl-1 -pyrazblyl)borato molybdenum [526] [37] pp 151 and 188... 

The reaction is thought to proceed with the dissociation of CT followed by release of the extra charge of the mthenium complex by dissociating a proton from the alkyhdene hgand. Such an exchange in itself does not lead to the decomposition of the alkyhdene complex. Nevertheless, both the formation of the charged species, both the intermediate existence of the carbyne complex (Scheme 9.5) may open new ways to the deterioration of the ROMP catalysts. 

Following the synthesis of metal carbyne complexes, the first metalladiyne derivative was prepared by treatment of W =C(OEt)C=CPh (CO>5 with BX3 (X = C1, Br, I) (pentane, -45°C) to give rranj-W(=CC=CPh)(X)(CO)4 (334 Scheme 77) in good yields (30-60%). Subsequent reactions with NHMea give W sCCH=CPh(NMc2) (X)(CO)4 by addition to the C=C triple bond, the structure of which indicates a contribution from the vinylidene resonance form. ... 

Table 1.4 Some vinylidene complexes, L M=C=CRR, obtained from carbynes.

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