Unusual reactivities of (μ-η2:η2-FP-CC-H)Co2(CO)6, the adducts of FP-CC-H to Co2(CO)8: photolysis, thermolysis and reduction with hydrosilanes giving polynuclear complexes, (CP)2Fe2Co3(μ5-C=CH)(CO)10, (μ-CH=CH)3-C)Co3(CO)9>2 and CpFeCo3(μ-C=CH2)(CO)9

Article abstract of DOI:10.1016/0022-328X(94)80118-5

The properties and reactivities of (μ-η²:η²-FP-C<*>C-H)Co2(CO)6 (3) C-H adducts to Co2(CO)8: 3a (FP = Fp), 3b (FP = Fp^*)> have been compared with those of alkyne adducts (μ-η²:η²-R-C<*>C-R)Co2(CO)6 and the Ph analogue (μ-η²:η²-Fp-C<*>C-Ph)Co2(CO)6 (5).Compound 3 has been shown to serve as a building block for polynuclear complexes. 13CO-labelling experiments on 3a and 5 have revealed an intramolecular exchange between the Fe-CO and Co-CO ligands.Photolysis of 3a, b produces pentanuclear clusters (CP)2Fe2Co3(μ₅-C=CH)(CO)10 (11a,b), respectively, via an apparent addition reaction of a (CP)FeCo(CO)n fragment to 3.On the other hand, thermolysis of 3a gives the Fe-free hexacobalt cluster compound (μ-C=CH)<(-μ₃-C)Co3(CO)9>2 (13) which consists of two alkylidyne tricobalt units linked by the CH=CH bridge, whereas 3b is thermolyzed to give the Fe-Co dimer without the C2H ligand, Cp^*Fe(CO)(μ-CO)2Co(CO)3 (14), in addition to the photolysis product 11b.Reduction of 3 with hydrosilanes gives a mixture containing 1,2-disilylethylene (16) and the tetranuclear μ-vinylidene cluster CpFeCo3(μ₄-C=CH2)(CO)9 (12) formally by way of hydrosilylation and hydrometallation (with a HCo(CO)n species) of the C2H ligand, respectively.In the case of the Pauson-Khand reaction and catalytic cyclotrimerization 3a exhibits reactivities similar to alkyne adducts to give the tricyclic cyclopentenone derivatives 18 (from norbornene and norbornadiene) and triphenylbenzenes, respectively. Key words: Iron; Cobalt; Carbonyl; Polynuclear