Reactions of co-ordinated ligands. Part 20. Insertion and ring-forming reactions of fluorinated olefins with η3-allylcobalt species; molecular and crystal structure of dicarbonyl[4–5-η-1,2-difluoro-1,2-bis(trifluoromethyl)pent-4-enyl](trimethyl phosphite)cobalt
Abstract
Thermal reaction of C2F4 with [Co(CO)2(PMe2Ph)(η-C3H5)], [Co(CO)2{P(OMe)3}(η-C3H5)], or [Co(CO)3-(η3-1-syn-PhC3H4)] affords respectively [C[graphic omitted]CH2)(CO)2(PMe2Ph)], [C[graphic omitted]CH2)-(CO)2{P(OMe)3}], and [C[graphic omitted]CHPh)(CO)3]. Hexafluoropropene with [Co(CO)2{P(OMe)3}-(η3-2-MeC3H4)] and octafluorobut-2-ene with [Co(CO)3(η-C3H5)], [Co(CO)2{P(OMe)3}(η-C3H5)], or [Co(CO)2-(PMe2Ph)(η-C3H5)] give [C[graphic omitted]CH2}(CO)2{P(OMe)3}], [C[graphic omitted]CH2}(CO)3], [C[graphic omitted]CH2}(CO)2{P(OMe)3}], and [C[graphic omitted]CH2}-(CO)2(PMe2Ph)] respectively. The penultimate compound is structurally identified by single-crystal X-ray diffraction. Crystals are triclinic, space group P![[1 with combining macron]](https://www.rsc.org/images/entities/char_0031_0304.gif)
, in a unit cell of dimensions a= 9.544(9), b= 11.682(9), c= 12.421(12)Å, α= 122.27(6), β= 119.78(6), and γ= 96.04(7)° at 183 K. The structure is essentially trigonal bipyramidal with the fluoroalkyl group and the phosphite ligand occupying axial sites. Chlorotrifluoroethylene with [Co(CO)3(η-C3H5)], [Co(CO)3(η3-2-MeC3H4)], and [Co(CO)3(η3-1-MeC3H4)] leads to an unusual cyclisation reaction and the formation of [Co{η3-[graphic omitted]H2}(CO)2], [Co{η3-[graphic omitted]H2}-(C0)2], and [Co{η3-[graphic omitted]H2}(CO)3]
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