Joseph S. Merola

Organocobalt cluster complexes : XXVI. Thermolysis of alkylidynetricobalt nonacarbonyl complexes. Evidence for carbyne intermediates

Abstract The thermolysis of methylidynetricobalt nonacarbonyl, HCCos 3 (CO) 9 , in refluxing xylene solution gives a mixture of CH 3 CCo 3 (CO) 9 and C 2 H 5 CCo 3− (CO) 9 . A reaction course involving the generation of a carbyne, HC:, and its addition to the CCo 3 core of the HCCo 3 (CO) 9 molecule, followed by extrusion of Co(CO) 3 to give acetylenehexacarbonyldicobalt and finally decomposition of the latter to form CH 3 CCo 3 (CO) 9 , is suggested. A separate experiment confirmed that the last step can occur.

[η5-cyclopentadien-1-YL-η4-tetraphenylcyclobutadienecobalt]diphenylmethylium hexafluorophosphate: A metal-stabilized carbonium ion salt

Abstract Mercuration of η5-cyclopentadienyl-η4-tetraphenylcyclobutadienecobalt, followed by transmetalation with n-butyllithium and reaction of the lithium derivative with benzophenone gave η4-Ph4C4Coη5-C5H4CPh2OH. Treatment of this alcohol produced the [η4-Ph4C4CoC5H4CP2]+ cation. This species reacted as a carbon electrophile with methanol, monomethylamine and N-methylpyrrole, as a cobalt electrophile with N,N-dimethylaniline and anisole. In the latter process the C5H4CPh2 ligand was displaced and the η6-arene-η4-tetraphenylcyclobutadienecobalt complexes were formed. Similar reactions with benzene, toluene and mesitylene proceeded only in the presence of aluminum chloride. The bonding in the cation is discussed on the basis of this chemistry and 13C NMR studies.

Organocobalt cluster complexes XXXI. the reactions of bromo- and chloro- methylidynetricobalt nonacarbonyl with thiols and lithium thiolates☆

Abstract The action of alkanethiols on bromomethylidynetricobalt nonacarbonyl in the presence of the triethylamine gives thioesters, RSC(O)CCo 3 (CO) 9 , as principal products, but arenethiols react to give tars. A more useful reactions is that between arenethiols and ClCCo 3 (CO0 9 , which gives ArSCCo 3 (CO) 9 complexes as the principal products. The actions of lithium alkane- and arenethiolates on BrCCo 3 (CO) 9 in hydrocarbon medium leads to formation of thioesters, but in the presence of triethylamine or in dietyl ether solution complexes of type Co 3 (CO) 4 (SR) 5 are formed instead. Possible mechanisms of these reactions are discussed.

The action of thiols and thiolates on halomethylidynetricobalt nonacarbonyls: A multiplicity of reaction paths☆

Abstract The action of alkanethiols and of lithium alkanethiolates on bromomethylidynetricobalt nonacarbonyl gave products of type RSC(O)CCo3(CO)9. This type of product also was obtained in a reaction of LiSC6H5 with the cobalt complex, but the action of an arenethiol on bromomethylidynetricobalt nonacarbonyl or on the analogous chloro compound in the presence of triethylamine gave ArSCCo3(CO)9 complexes and products of partial cluster degradation, Co3(CO)4(SAr)5. Complexes of type RSC(O)CCo3(CO)9 decomposed when heated in refluxing benzene under nitrogen, giving decarbonylation products, RSCCo3(CO)9, in low yield.