Structures and some reactions of π-diene derivatives of octacarbonyldicobalt
- 1 January 1973
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 15,p. 1593-1595
- https://doi.org/10.1039/dt9730001593
Abstract
Norbornadiene and conjugate dienes react with Co2(CO)8 to give {(π-diene)Co2(CO)6}(I) and then {(π-diene)-Co(CO)2}2(II)(diene = norbornadiene, isoprene, and 2,3-dimethylbuta-1,3-diene). The hexacarbonyl derivatives (I) are not tautomeric, and have structures based on that of the bridged isomer of octacarbonyldicobalt. Both (I) and (II) react with iodine to give {(π-diene)Co(CO)2I} derivatives which could be detected but not isolated, with SnX4 to give mixtures of {(π-diene)Co(CO)2SnX3} and {Co(CO)4SnX3}(X = Cl, Br, or I), and with Ph3PAuCl, HgX2, and Ph3SnCl to give only Ph3PAuCo(CO)4, Hg{Co(CO)4}2, and Ph3SnCo(CO)4 respectively. Monodentate tertiary phosphines convert (I) to a mixture of (II) and {(R3P)Co(CO)3}2via the unstable intermediate ionic species [(π-diene)Co(CO)2PR3][Co(CO)4]. Similar salts are stable and have been isolated with Ph2PCH2CH2PPh2i.e.[{(π-diene)Co(CO)2}2{Ph2PCH2CH2PPh2}][Co(CO)4]2. They are reduced by NaBH4 to {(π-allyl)Co(CO)2}2{Ph2PCH2CH2PPh2}. The i.r. spectra of the products are reported and their structures discussed. The reactions are compared, and contrasted, with those of the related isoelectronic and isostructural π-cyclopentadienyl complexes of iron.Keywords
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